Progress 05/01/11 to 09/30/15
Outputs
Target Audience:The target audience would be any individual or agency interested in the fishes and aquatic resources of California. This would include academic researchers, as well as state and federal agencies. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Several undergraduate students, PhD students and postdoctoral researchers contributed to this research. None were financially supported by the project, but contributed as part of other funded research. A total of six undergraduate students were involved in the morphological project with native and invasive species, each spending at least year in the lab. PhD student Andrew Carroll was instrumental in developing the biomechanical model of fish feeding performance and published one paper in this period on using the model with invasive California species. PhD student Tyler Skorczewski from the Math Department at UC Davis, conducted a computational fluid dynamic study that helped us better understand the importance of mouth aperture shape in suction feeding performance. He published this paper. PhD student Matthew McGee conducted the research on hybrid sunfishes and published one paper form this project. Postdoc Roi Holzman then used the model to more fully evaluate suction feeding performance in all native and invasive species in California. He worked with two undergraduates and a PhD student and published two papers on this research. How have the results been disseminated to communities of interest?Several research papers were published from this research, each in a peer-reviewed scientific journal. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
All five of the major goals of this project were successfully met. Working with a group of 4 undergraduate researchers from UC Davis, we obtained accessioned specimens from collections at the UC Davis Fish and Wildlife collection and the California Academy of Sciences, of 64 native species and all 51 alien species. We measure a set of 17 morphological traits from the specimens that relate to locomotor and feeding performance. Comparisons of occupation of morphospace by native and invasive species indicated a much more clumped pattern in the natives with closely related species tending to look alike, while the invasive species had over twice as high variance among species. Several areas of morphospace not occupied by natives were occupied by invasive species. Using Particle Image Velocimetry, we were able to obtain complete data on the flow profiles of feeding in two major invasive species. Using these data were developed a mechanical model using morphological traits to predict maximal suction feeding capabilities of individual fish. The approach described above was then used to estimate suction feeding force in all native and invasive species. The results revealed that 12 of the invasive species have suction feeding abilities beyond that found in any native species. Our results suggest that invasive species have, in part, been successful because of high performance feeding abilities that evolved in other parts of the world. The majority of native species are not predatory in their ecology, mostly feeding on small insects and algae. These 12 high suction performance invaders are all predatory species that feeding on elusive prey such as other fishes and large invertebrates. Finally, in an extension of this research, we studied hybridization among invasive species to better understand their impact on native habitats. Working with an exemplar population in Napa County we collected bluegill, green sunfish and their hybrids. Body shape was compared among the three groups and lab experiments with live fish were performed. Fish were filmed with 1000 Hz video feeding in aquaria on small fishes and the skeletal dynamics and biomechanical performance of each group was measured and compared. Results revealed that bluegill are superior predators on benthic attached prey, while green sunfish perform best when feeding on active elusive prey. Hybrids were intermediate in performance, but were always worse than the better of the two parent species. These results indicate that hybrids are at a selective disadvantage in California waterways and are unlikely to be a particular invasive menace.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2011
Citation:
Carroll, A. M. and P. C. Wainwright. 2011. Scaling of in vivo velocity during feeding in the largemouth bass, Micropterus salmoides (Centrarchidae). Physiological and Biochemical Zoology. 84:618-624.
- Type:
Journal Articles
Status:
Published
Year Published:
2012
Citation:
Holzman, R., D. C. Collar, R. S. Mehta & P. C. Wainwright. 2012. An integrative approach to elucidate suction feeding performance. Journal of Experimental Biology. 215:1-13.
- Type:
Journal Articles
Status:
Published
Year Published:
2012
Citation:
Staab, K. L., R. Holzman, L. P. Hernandez & P. C. Wainwright. 2012. Independently evolved upper jaw protrusion shows convergent hydrodynamic function in teleost fishes. Journal of Experimental Biology. 215:1456-1463.
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
Wainwright, P.C., M.D. McGee, S.A. Longo and L.P. Hernandez. 2015. Suction feeding in vertebrates: origins, innovations and diversification. Integrative and Comparative Biology. 55:134-145.
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
McGee, M. D., J. W. Reustle, C. E. Oufiero and P. C. Wainwright. 2015. Intermediate kinematics produce inferior feeding performance in a classic case of natural hybridization. American Naturalist. 186:807-814.
- Type:
Journal Articles
Status:
Published
Year Published:
2012
Citation:
Skorczewski, T., A. Cheer and P. C. Wainwright. 2012. The benefits from flat circular mouths on suction feeding performance. Journal of the Royal Society, Interface. 9:1767-1773.
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Progress 10/01/13 to 09/30/14
Outputs
Target Audience: This research concerns the ecological dynamics on non-native freshwater fishes in the state of California. Our target audience includes state workers charged with tracking invasive species impacts and managing populations, scientists in California and elsewhere who work with these fishes and these issues, and the public who should be better informed about the issues. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? This research provided an opportunity for one PhD student (Matthew McGee) to conduct research and was the basis for one undergraduate honors thesis (Matthew Sperrow). How have the results been disseminated to communities of interest? A manuscript has been prepared, but is not yet published, and a presentation was given at the undergraduate research conference at UC Davis in spring of 2014. What do you plan to do during the next reporting period to accomplish the goals? We plan to publish this paper and extend our study of freshwater fish communities to other sites in Northern California. We plan to sample populations of non-native sunfishes and examine the imapct of presence or absence of other closely related species on the morphology and ecology of the target species.
Impacts
What was accomplished under these goals?
In the past year we conducted a detailed study of hybridization between invasive species of sunfish in California farmpond systems. Working with an exemplar population in Napa County we collected bluegill, green sunfish and their hybrids. Body shape was compared among the three groups and lab experiments with live fish were performed. Fish were filmed with 1000 Hz video feeding in aquaria on small fishes and the skeletal dynamics and biomechanical performance of each group was measured and compared. Results revealed that bluegill are superior predators on benthic attached prey, while green sunfish perform best when feeding on active elusive prey. Hybrids were intermediate in performance, but were always worse than the better of the two parent species. These results indicate that hybrids are at a selective disadvantage in California waterways.
Publications
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Progress 01/01/13 to 09/30/13
Outputs
Target Audience: The target audience for this work includes other research scientists working in related areas, including university faculty, graduate students and postdoctoral scholars, and particularly wildlife managers concerned with California’s invasive fish species and the conservation biology of native, freshwater fishes of California. The California Department of Fish & Game is a good example of a state agency with a major stake in understanding the mechanisms of success for invasive fish species. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Matthew McGee, a PhD student worked on the stickleback projects, publishing three papers. How have the results been disseminated to communities of interest? Our publications have been made available on our laboratory website. In addition seminar presentations were made at two conferences (American Society of Integrative and Comparative Biology and Society for the Study of Evolution). Finally, Matt McGee and the PI gave separate presentations to the Sacramento Aquarium Society. What do you plan to do during the next reporting period to accomplish the goals? We plan to extend the morphospace analysis to understand how species are packed into communities in terms of their morphology and functional design. We are looking for functional complementarity at the level of assemblages, and communities of interacting and co-occurring species. We also will use our biomechanical model of suction feeding to begin characterizing the functional diversity of communities and the relationship between these morphological traits and community diversity and presence of invasive species.
Impacts
What was accomplished under these goals?
Morphometric data were collected on a sample of all species of native freshwater California fishes and the 50 most established invasive fish species. The diversity of shape in this sample was evaluated with morphometric methods to determine the extent to which invasive species have accessed unused regions of morphospace. The analyses revealed that California fishes are clustered in two regions of space while the introduced fishes are considerably more diverse than the natives and occupy extensive regions of space not occupied by natives. The exotic species have greatly expanded the morphospace of California's freshwater fish fauna, increasing it by about 100%. An analysis of stickleback morphology was completed that led to three publications during this period. We evaluated the morphological and functional differences between male and female freshwater stickelbacks and found major differences in the degree of jaw protrusion which is greater in females. This appears to be tied to their nesting habit, as males build and modify nests, resulting the loss of protrusion to stabilize the jaws. We showed that freshwater invasions generate high morphological diversity while converging functionally. We evaluated how freshwater invasions of stickleback are modified functionally and found that functional changes are diverse, being similar in their mechanical implications for the feeding mechanism but quite different in the underlying morphological changes. We analyzed the functional morphology of feeding in a large family of fishes that is represented in coastal waters of California, Epinephelidae. From high speed video recordings of prey capture events we distilled traits that describe the movements associated with prey capture. The major axis of diversity identified was between species that launch high-speed attacks and species that ambush prey with short lunges. These patterns will have important implications for the freshwater fauna of California because many of hte inasive species are thought to occupy novel regions of the function space, that is they feed in ways not seen in the native fauna.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
McGee, M. D. and P. C. Wainwright. 2013. Sexual dimorphism in the feeding kinematics of threespine stickleback. Journal of Experimental Biology. 216:835-840.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
McGee, M. D. and P. C. Wainwright. 2013. Convergent evolution as a generator of phenotypic diversity in threespine stickleback. Evolution. 67:1204-1208.
- Type:
Journal Articles
Status:
Published
Year Published:
2012
Citation:
Oufiero, C. E., R. A. Holzman, F. A. Young & P. C. Wainwright. 2012. New insights from serranid fishes on the role of trade-offs in suction feeding diversification. Journal of Experimental Biology 215:3845-3855.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
McGee, M. D., D. Schluter and P. C. Wainwright. 2013. Functional basis of ecological divergence in sympatric stickleback. BMC Evolutionary Biology. 13:277.
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Progress 01/01/12 to 12/31/12
Outputs
OUTPUTS: The primary new output of this project has been the development of a global data base of body form in all fishes that we are using as a reference for comparing the radiation of species in California. This data set includes detailed morphological information on 3,219 species that are being compared to the 93 fish species that are either endemic to California or introduced and well established in the state. Our results have been communicated to many audiences. We published three papers in the primary scientific literature and made public presentations around California (Sacramento Marine Aquarium Group, University of California, Santa Cruz). We extended our Youtube channel of high-speed videos of fish feeding and this channel reached 1,000,000 views from the public, making it very highly accessed resource. We published a paper (Boettiger et al 2012) that introduces a tool for us in R that allow one to quickly extract information from the online fish information resource Fishbase. Wainwright consulted on three television documentaries and sixe press releases. Ten oral presentations were presented by Wainwright, postdoctoral fellows, graduate students and undergraduate students at the annual meetings of the Society for Integrative and Comparative Biology, Society for the Study of Evolution, and the Society for the Vertebrate Paleontology. PARTICIPANTS: Two postdoctoral researchers worked on this project: Thomas Claverie and Lars Schmitz. Two undergraduate students were instrumental in developing the large morphological data set: Trinh Lee and Johanna Lee. Dr. Schmitz has moved to a faculty position while both undergraduate continuing to do research in the lab and are planning to attend graduate school. TARGET AUDIENCES: The target audience for this work includes other research scientists working in related areas, including university faculty, graduate students and postdoctoral scholars, and particularly wildlife managers concerned with California's invasive fish species and the conservation biology of native, freshwater fishes of California. The California Department of Fish & Game is a good example of a state agency with a major stake in understanding the mechanisms of success for invasive fish species. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Our morphological data set of fishes focuses on morphological traits that reflect mechanical adaptation of the musculoskeletal system, particularly the systems used in feeding, locomotion and sensory systems. This allows us to describe a morphospace for fishes that is interpretable in terms of the abilities of the fish to swim and to feed on different prey. The morphospace is therefore likely to closely match the ecological diversity of the species. We first developed this approach through intensive analysis of centrarchid fishes to understand the design of their feeding and swimming systems and in the past year we have extended this approach to include all species of California's freshwater fish fauna. By placing fish species in this morphospace we are able to determine their functional design relative to other species. By comparing California's freshwater fishes to this overall fish morphospace we have determined that the radiation of fish in California, about 50 species, represents a highly non-random sample of the morphospace covered by all fishes. Interestingly, the invasive fish species found in California represent much more morphological variation than the native species and are consistent with a random sample of their morphology. We have developed a model that simplifies the essential mechanical events in suction feeding. The model can be parameterized by making a series of relatively simple morphological measurements from the body of fishes and is used to calculate the capacity to generate suction water flow. We have developed similar models for other aspects of feeding and swimming and by using them we are able to describe the functional abilities of fish on these two fundamental aspects of movement: locomotion and feeding. By applying this approach to all species of freshwater fishes in California we have produced a map of functional diversity of these fishes. Work with this model indicates that the California radiation has not evolved an high performance suction feeders, while many invasive species score in the high performance range. In contrast California fishes often show very high performance design in locomotion. We will be trying to understand the role of these differences in the dynamics of the invasion process.
Publications
- Boettiger, C., D. Temple-Lang and P. C. Wainwright. 2012. rfishbase: exploring, manipulating and visualizing FishBase data in R. Journal of Fish Biology. 81:2030-2039.
- Near, T. J., M. Sandel, K. L. Kuhn, P. J. Unmack, P. C. Wainwright and W. L. Smith. 2012. Nuclear gene-inferred phylogenies resolve the relationships of the enigmatic pygmy sunfishes, Elassoma (Teleostei: Percomorpha). Molecular Phylogenetics and Evolution. 63:388-395.
- Staab, K. L., R. Holzman, L. P. Hernandez & P. C. Wainwright. 2012. Independently evolved upper jaw protrusion shows convergent hydrodynamic function in teleost fishes. Journal of Experimental Biology. 215:1456-1463.
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: The primary output this year was the further development of a biomechanical model of suction feeding musculo-skeletal function that can be used to estimate fine-scale feeding performance of fishes based on morphological measurements and some data developed from videos of feeding. The model has been made publically available. The development and dissemination of this model has allowed us to meet a primary goal of this project and is being used to study diversity of suction feeding mechanisms in communities of California's freshwater fishes, including both native and non-native species. Our results have been communicated to audiences at many levels. We published one article in the primary scientific literature, and made public seminars around the state (Moss Landing Marine Laboratory, Bodega Marine Laboratory, University of California, Irvine). PI Wainwright consulted on two new television documentary shows produced in Japan for Japanese television. Twelve papers were presented by Wainwright, postdocs, students and collaborators at the annual meetings of the Society for Integrative and Comparative Biology, and the American Society of Ichthyologists and Herpetologists. PI Wainwright launched an educational blog. PARTICIPANTS: Select one of the following options: a) Not relevant to this project b) Nothing significant to report during this reporting period X c) Report narrative entered in the box below If c) is checked, narrative must be entered in this block (below). One graduate student, Tyler Skorczewski, and one postdoctoral researcher, Roi Holzman, worked on this project. Dr. Skorczewski is now a postdoctoral researcher at the University of Utah, and Dr. Holzman is a faculty member at the University of Tel Aviv in Israel. TARGET AUDIENCES: Select one of the following options: a) Not relevant to this project b) Nothing significant to report during this reporting period X c) Report narrative entered in the box below If c) is checked, narrative must be entered in this block (below). The target audience for this project includes (1) other research scientists working in related areas, including university faculty, graduate students and postdoctoral scholars, and particularly (2) wildlife managers concerned with invasive fish species and conservation biology of native, freshwater fishes of California. The California Department of Fish & Game is an example of a state agency with a major stake in understanding the mechanisms of success for invasive fish species. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
We feel that the most important outcome of this project has been the development and further refinement of a biomechanical model of the suction feeding mechanism of fishes. The model provides a basis for estimating feeding performance in fishes based on anatomical measurements and behavioral observations. This model provided a mechanistic explanation for the comparatively poor suction feeding ability of the one native species of freshwater fish in California, the Sacramento Perch, that has been displaced in its native range by introduced species of the same family. The model has been made available publically, the results of the analysis of Sacramento Perch were published in the primary scientific literature and have been the focus of several seminars given in the state and at national meetings. Almost all fish capture their prey using suction feeding, a mechanism in which the mouth and oral cavity are rapidly expanded to create a flow of water into the mouth aperture. This draws water and prey into the fish's mouth. Suction feeding performance is a function of the ability to generate a strong suction pressure - where this pressure is proportional to the velocity of the water flow into the mouth that the fish generates. Strong pressure gradients and high velocity flow are features of high performance suction feeding. For a given amount of feeding muscle a fish's feeding system can be optimized by evolution to either produce high velocity flows or to capture a large volume of water. These capacities relate to different feeding strategies and this trade-off reveals fish species as being adapted for different types of prey. This model and our experiments with feeding fishes allowed us to conclude that the native Sacramento Perch is almost exactly intermediate in suction feeding performance on these two axes compared to non-native members of this family. They cannot generate as high a flow velocity as some introduced species of the same family, and cannot capture as much volume as three other species. We propose that this intermediate suction feeding design renders this species an inferior competitor in the face of the invasive Bluegill Sunfish and Largemouth Bass, which specialize on high flow velocity and high volume suction feeding, respectively. The Sacramento Perch cannot feed effectively on Bluegill prey and cannot feed with high performance on Largemouth Bass. As a result Sacramento Perch appear to be inferior competitors when feeding on their historical prey. In the last few months of the year we began extending this approach to analyze entire communities of freshwater fishes in California. Our aim is to contrast the feeding and locomotor performance in all native and introduced fish species in the California's waterways. Preliminary data indicate that several successfully invasive fish species have feeding performance profiles that fall outside the range of the native fauna, while some species fall well within this range. By further developing this approach we hope to make the freshwater fish communities of California a model analyzing the impact of feeding and locomotor performance traits in predicting the success of invasive species.
Publications
- Skorczewski, T., P. C. Wainwright, A. Cheer, S. Cheung. 2010. Use of computational fluid dynamics to study forces exerted on prey by aquatic suction feeders. Journal of the Royal Society, Interface. 7:475-484.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: The research primary output this year is the development of a model that allows us to evaluate the mechanical basis of suction feeding performance in suction feeding fish species. The development of this model has allowed us to meet of the primary goals of our project and will be used to study diversity of suction feeding mechanisms. Results have been communicated to the widest possible audiences. We published two articles in the primary scientific literature, made public seminars around the state, have consulted on two new television documentary shows that were shown in California and on national television in 2009 and were watched millions of viewers. Presentations were made at the annual meetings of the Society for Integrative and Comparative Biologiy, the American Society of Ichthyologists and Herpetologists, at the Bodega Marine Laboratory, the Moss Landing Marine Laboratory, and the University of California, Davis. The Principal Investigator worked with on an Animal Planet television show about aquatic predation and with ESPN about a show that featured one of our high-speed videos of feeding fishes. The Animal Planet show included some results from this research. The ESPN show was viewed by almost 12 Million people country-wide. PARTICIPANTS: One graduate student, Andrew Carroll, and one postdoctoral researcher, Roi Holzman, worked on this project. Dr. Carroll is now a faculty member at the University of Evansville, and Dr. Holzman is still here at UC Davis in my laboratory. TARGET AUDIENCES: Our target audience includes (1) other research scientists working in related areas, including university faculty, graduate students and postdoctoral scholars, and (2) wildlife managers concerned with invasive fish species and conservation biology of the Sacramento Perch, an endemic California native. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
We developed a biomechanical model of the suction feeding mechanism of fishes that provides a basis for interpreting the diversity of feeding performance in fishes. This model provides a specific, mechanical explanation for the relatively poor suction feeding performance on a native species of freshwater fish in California that has been displaced in its native range by introduced species of the same family. These results have been published in the primary scientific literature and have been the focus of several seminar given in the state and at national meetings. Most fish capture their prey using suction feeding, a mechanism found only in bony fishes in which the mouth and oral cavity are rapidly expanded to create a flow of water into the mouth aperture. This draws water and prey into the fish's mouth. Suction feeding performance is a function of the ability to generate a strong suction pressure - where this pressure is proportional to the velocity of the water flow that the fish generates. High pressure gradients and high velocity flow are features of high performance suction feeding. For a given amount of feeding muscle a fish's feeding system can be optimized by evolution to either produce high velocity flows or to capture a large volume of water. These capacities relate to different feeding strategies and this trade-off reveals fish species as being adapted for different types of prey. This model and our experiments with feeding fishes allowed us to conclude that the native Sacramento Perch is almost exactly intermediate in suction feeding performance on these two axes compared to non-native members of this family. They cannot generate as high a flow velocity as some introduced species of the same family, and cannot capture as much volume as three other species. We propose that this intermediate suction feeding design renders this species an inferior competitor in the face of the invasive Bluegill Sunfish and Largemouth Bass, which specialize on high flow velocity and high volume suction feeding, respectively. The Sacramento Perch cannot feed effectively on Bluegill prey and cannot feed with high performance on Largemouth Bass. As a result Sacramento Perch appear to be inferior competitors when feeding on their historical prey. An additional set of experiments were used to establish mechanisms that the invasive Bluegill Sunfish uses to approach small crustacean prey without alert them to their presence. This is done by minimizing the bow wake produced by the moving fish body - created when the fish's body pushes water in front of it as it swims. Small crustaceans are very good at detecting this bow wake. Bluegill are very skilled at minimizing this bow wake and our preliminary data indicate that Sacramento Perch create a large bow wake and are unable to achieve the minimization found in Bluegill. These differences in feeding performance are correlated with the success of introduced Bluegill and Largemouth Bass, and the loss of Perch from their native habitats.
Publications
- Carroll, A.M. & P.C. Wainwright. 2009. Energetic limitations on suction feeding performance in Centrarchidae. Journal of Experimental Biology. 212: 3241-3251.
- Holzman, R. & P.C. Wainwright. 2009. How to surprise copepod: Strike kinematics reduce hydrodynamic disturbance and increase stealth of suction feeding fishes. Limnology and Oceanography 54, 2201-2212.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: The outputs this year include results from several experiments, publications that result from those experiments. Our research this year allowed us answer one of the primary questions set out in our project. The results have been shared with the widest possible audience by publishing them in scientific journals, giving public seminars and helping produce a television documentary. In addition, results were presented in oral presentations at national meetings of the American Society of Ichthyologists and Herpetologists and Society for Integrative Biology. Finally, oral seminars were presented to interest groups at the Bodega Marine Laboratory, Moss Landing Marine Laboratory, University of Louisiana Lafayette, University of Oregon and University of California, Los Angeles. Finally, the PI worked with National Geographic as the on-screen scientific expert in an internationally aired one-hour television documentary on the conservation status of five giant species of fishes found in California and around the world. Some findings from this research we discussed in that show. This television show has been viewed by millions of Americans. PARTICIPANTS: Two postdoctoral researchers supported by grants from the National Science Foundation here at UC Davis contributed to this project, Roi Holzman and Rita Mehta. Participation in our project also came from a colleague at Rochester Institute of Technology, Professor Steven Day who is in their Department of Mechanical Engineering. TARGET AUDIENCES: Our target audience includes (1) other research scientists working in related areas, including university faculty, graduate students and postdoctoral scholars, and (2) wildlife managers concerned with invasive fish species. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Our experimental results change existing understanding of fluid mechanics of fish feeding and particularly what effect ambient flows may have on different kinds of suction feeders. We believe that this has major implications for understanding why some fish species successfully invade river habitats in California and others do not. These results and hence the reasons are explained in our publications and in seminars. When suction-feeding vertebrates expand their buccal cavity to draw water into their mouth, they exert a hydrodynamic force on their prey. This force is key to strike success, directly countering forces exerted by escaping or clinging prey. While the ability to produce high flow accelerations in front of the mouth is central to the predator's ability to exert high forces on the prey, several mechanisms can contribute to the disparity between the potential and realized performance through their effect on flow and acceleration as experienced by the prey. In this research we tested how interspecific variation in gape size, mouth displacement speed and the fish's ability to locate prey at the optimal position affect variation in the force exerted on attached prey. We directly measured these forces by allowing bluegill sunfish and largemouth bass to strike at ghost shrimp tethered to a load cell that recorded force at 5000Hz, while synchronously recording strikes with a 500Hz video. Strike kinematics of largemouth bass were slower than that of bluegill, as were estimated flow speeds and the force exerted on the prey. This difference in force persisted after taking into account the faster suction flows and accelerations of bluegill, and was only accounted for by considering interspecific differences in gape size, mouth displacement speed and fish's ability to locate the prey at the optimal position. The contribution to interspecific differences in the force exerted on the prey was estimated to be 42 percent for flow speed, 25 percent for strike efficiency, 3 percent for gape size and 30 percent for mouth displacement speed. Hence, kinematic diversity results in substantial differences in suction performance, beyond those expected based on the capacity to generate a high flow velocity. This functional complexity, in the form of biomechanically independent mechanisms that are recruited for one function, can potentially mitigate performance trade-offs in suction-feeding fishes.
Publications
- Holzman, R., S. W. Day, R. S. Mehta & P. C. Wainwright. 2008. Integrating the determinants of suction feeding performance in fishes. Journal of Experimental Biology. 211:3295-3305.
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Progress 01/01/07 to 12/31/07
Outputs
We study the mechanical basis of differences between fish species in prey capture ability. Our work focuses on suction feeding, a mechanism that is used by the vast majority of fishes to capture their prey. We discovered that jaw protrusion amplifies the suction forces exerted on prey by predatory fishes. This is the first mechanical benefit of jaw protrusion, a feature that is found in about half of all living fish species. Jaw protrusion causes acceleration of fluid around the prey to be greater than a fixed position of the mouth, and because the major forces exerted on the prey are due to acceleration of the fluid this results in higher suction forces being experienced by the prey item. This provides insight into why fish species may differ in jaw protrusion ability, suggesting that this capability is most likely to be found in species that rely on strong suction feeding to capture their prey. Variation in jaw protrusion characterizes the difference between bluegill
and largemouth bass, two common freshwater fishes in California. Bass use swimming to overtake prey and do not rely on suction, while bluegill have high jaw protrusion and use suction to dislodge invertebrate prey that cling to holdfasts in the environment. Both species are highly successful invasive species. Suction feeding fish rapidly expand their skull to generate a flow of water into the mouth that is used to entrain and capture prey items. Using a mathematical model of the forces that suction feeders exert on their prey we calculated the magnitude of drag, acceleration reaction and pressure gradient force that would be exerted on prey under three different scenarios. Pressure gradient was found to dominate the forces experienced by prey of suction feeders, an important discovery that is in marked contrast to previous considerations of this problem that estimated drag to be the largest component of the force. This is the first mechanical advantage recognized for the small mouth
that characterizes many species of fish thought to be high performance suction feeders. Experimental results made with a digital Partical Image Velocimetry system showed that largemouth bass have poorer strike accuracy than bluegill but generate higher water flux into the mouth (volume ingested per time). These results allowed us to identify specific design features of bluegill that make them superior suction feeders than largemouth bass in terms of the forces they exert on prey. They generate higher water velocity and acceleration and their smaller mouth amplifies these differences and results in a much higher net force exerted on prey, about 3-fold, than seen in largemouth bass. Bass are able to feed while swimming very rapidly, ingest a large volume of water and show higher performance than bluegill on large elusive prey items. These differences in feeding performance allow us to understand why these species are able to coexist in local freshwater habitats. Our results are being
published in the primary literature. Members of the laboratory gave 12 presentations and international meetings on this research and subsequently discussed their findings with other members of the research community.
Impacts
This research contributes to our understanding of the mechanical basis of feeding performance differences among invasive species of centrarchid fishes. Fundamental insights into why these species differ in their capacity to feed on different prey were gained by understanding how morphological and physiological differences in skull design result in differences in the water flow capabilities of the species during feeding behavior. The most important new finding is the role of jaw protrusion in enhancing suction forces exerted on prey item. The model used to interpret morphological variation was also used to reveal other differences between other centrarchid species that play different roles in local freshwater communities. We show that jaw protrusion has a major impact on the ability of suction feeding fishes to capture prey that resist their attacks.
Publications
- Day, S.W., T.E. Higham and P.C. Wainwright. 2007. Time resolved measurements of the flow generated by suction feeding fish. Fluids Research 43:713-724.
- Holzman, R., S.W. Day and P.C. Wainwright. 2007. Timing is everything: Effects of kinematic variation on the force exerted by suction feeding bluegill on their prey. Journal of Experimental Biology 210:3328-3336. Wainwright, P.C. and S.W. Day. 2007. The forces exerted by aquatic suction feeders on their prey. Journal of the Royal Society: Interface. 4:553-560.
- Wainwright, P.C., A.M. Carroll, D.C. Collar, S.W. Day, T.E. Higham and R.A. Holzman. 2007. Suction feeding mechanics, performance and diversity in fishes. Integrative and Comparative Biology 47:96-106.
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Progress 01/01/06 to 12/31/06
Outputs
This year we continued our studies that are designed to understand the basis of diversity among centrarchid fishes in feeding mechanics. Key progress in this past year was made in modeling and making measurements of the forces that suction feeding predators exert on their prey (centrarchid fishes like most fish are suction feeders). A second area of progress was made in measuring several aspects of suction performance in largemouth bass and bluegill, two species that have been icons for extremes of the performance spectrum found among centrarchid fishes. These two species also dominate the freshwater fish communities of California, where both are highly successful invasive species. Suction feeding fish rapidly expand their skull to generate a flow of water into the mouth that is used to entrain and capture prey items. Using a mathematical model of the forces that suction feeders exert on their prey we calculated the magnitude of drag, acceleration reaction and
pressure gradient force that would be exerted on prey under three different scenarios. Pressure gradient was found to dominate the forces experienced by prey of suction feeders, an important discovery that is in marked contrast to previous considerations of this problem that estimated drag to be the largest component of the force. The importance of pressure gradient indicated that the relatively small mouth of bluegill as compared to largemouth bass results in a steeper spatial pressure gradient in front of the feeding fish mouth, and hence a larger pressure gradient force. This is the first mechanical advantage recognized for the small mouth that characterizes many species of fish thought to be high performance suction feeders. Experimental results made in our lab with a digital particle image velocimetry system showed that largemouth bass have poorer strike accuracy than bluegill but generate higher water flux into the mouth (volume ingested per time). Bluegill generate higher fluid
velocities and accelerations in front of their mouth than largemouth bass. These results allowed us to identify specific design features of bluegill that make them superior suction feeders than largemouth bass in terms of the forces they exert on prey. The generate higher water velocity and acceleration and their smaller mouth amplifies these differences and results in a much higher net force exerted on prey, about 3-fold, than seen in largemouth bass. Bass are able to feed while swimming very rapidly, ingest a large volume of water and show higher performance than bluegill on large elusive prey items. These differences in feeding performance allow us to understand why these species are able to coexist in local freshwater habitats. They thrive on different prey resources. The effect of temperature on prey capture kinematics was measured and shown to be much less than expected from mechanical arguments, showing that largemouth are able to mitigate strong physical constraints on muscle
metabolism to execute very fast strikes, on the order of 10 millisecond, even in cold water.
Impacts
This research determined the mechanical basis of feeding performance differences among invasive species of centrarchid fishes. Fundamental insights into why these species differ in their capacity to feed on different prey were gained by understanding how morphological and physiological differences in skull design result in differences in the water flow capabilities of the species during feeding behavior. The model used to interpret morphological variation was also used to reveal other, more subtle differences between other centrarchid species that play different roles in local freshwater communities. The surprising ability of largemouth bass to mitigate acute thermal impacts on muscle performance, indicates a surprising ability of this species to conduct very high performance feeding behaviors in the face of expected limitations on the speed and power of movement.
Publications
- Higham, T. E., S. W. Day and P. C. Wainwright. 2006. The pressures of suction feeding: the relation between buccal pressure and induced fluid speed in centrarchid fishes. Journal of Experimental Biology. 209: 3281-3287.
- Collar, D. C. and P. C. Wainwright. 2006. Discordance between morphological and mechanical diversity in the feeding mechanism of centrarchid fishes. Evolution 60:2575-2584.
- De Vries, M. S. and P. C. Wainwright. 2006. Effect of acute temperature change on prey capture kinematics in largemouth bass, MICROPTERUS SALMOIDES. Copeia 2006(3): 436-443.
- Wainwright, P. C. and S. W. Day. 2007. The forces exerted by aquatic suction feeders on their prey. Journal of the Royal Society: Interface. IN PRESS.
- Higham, T. E., S. W. Day and P. C. Wainwright. 2006. Multidimensional analysis of suction feeding performance in fishes: fluid speed, acceleration, strike accuracy and the ingested volume of water. Journal of Experimental Biology. 209: 2713-2725.
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Progress 01/01/05 to 12/31/05
Outputs
We are conducting research on the biomechanical basis of prey capture performance in centrarchid fishes and on fluid mechanics of feeding in these fishes. This involves experiments using Particle Image Velocimetry (PIV), pressure measurements and high speed video. We have collected and published the first data set of empirical measurements of the flow field generated in front of a suction feeding fish, a bluegill sunfish, which has been widely introduced in California. PIV measurements of water velocity and particle tracking show that water is drawn from all around the mouth. After scaling the velocity field based on size of the mouth opening and the measured fluid speed at a fixed position, the measured velocity profiles for all feedings are very similar to one another so that a functional relationship for the magnitude of fluid speed as a function of distance from the predator mouth is presented and shown to be generally true over the range of kinematic variables
tested. This relationship is descriptive of the velocity field both along the centerline of the fish and along transects lying at an angle to the centerline within both the mid-sagittal and frontal plane. Comparison of the time resolved fluid velocity measurements to gape kinematics demonstrate that peak fluid speed occurs simultaneously with 95 percent of maximum mouth opening gape, showing that the bluegill nearly simultaneously maximizes both the generated forces and size of the region over which these forces act. Suction performance is commonly defined directly in terms of peak fluid speed entering the mouth, or indirectly in terms of peak subambient buccal pressure. A number of factors (size, shape, and flow rate) of the ingested volume of water, as well as the accuracy of a strike, are important in order to capture a prey item. We measured maximum fluid speed, fluid acceleration, accuracy, and the ingested volume of water to develop a comprehensive picture of suction
performance. We quantified the effects of gape, time to peak gape, and ram speed on several factors that characterize the ingested volume of water in largemouth bass and bluegill sunfish. We developed a new method for quantifying strike accuracy in which the prey location relative to the center of the parcel of ingested water was determined. Using PIV and high-speed video, we observed the flow in front of the mouth of three fish from each species using a vertical laser sheet positioned on the mid-sagittal plane of the fish. Bluegill sunfish generated higher fluid speeds and accelerations than largemouth bass. The average total ingested volume was 27.8 cm3 and 4.5 cm3 for largemouth bass and bluegill sunfish, respectively. This volume significantly increased as gape increased for both species, while time to peak gape had little effect on the volume. Based on the Accuracy Index, bluegill sunfish (AI equals 0.8) were almost twice as accurate as largemouth bass (AI equals 0.46). A number
of factors are important for determining suction performance. Bluegill sunfish are more accurate, generate higher fluid speeds, but have a much smaller ingested volume of water and volume flow rate than largemouth bass.
Impacts
We are producing a description of the mechanical capacity of three fish species, one early extinct native and two introduced and successful species, to generate suction pressures, water velocity and acceleration during prey capture. Understanding their feeding abilities will permit us to evaluate the role of competitive feeding interactions in determining the ability of introduced species to become established.
Publications
- Day, S. W., T. E. Higham, A. Y. Cheer and P. C. Wainwright. 2005. Spatial and temporal flow patterns during suction feeding of bluegill sunfish (LEPOMIS MACROCHIRUS) by Particle Image Velocimetry. Journal of Experimental Biology 208:2661-2671.
- Higham, T. E., S. W. Day and P. C. Wainwright. 2005. Sucking while swimming: evaluating the effects of ram speed on suction generation in bluegill sunfish (LEPOMIS MACROCHIRUS) using digital particle image velocimetry. Journal of Experimental Biology 208:2653-2660.
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Progress 01/01/04 to 12/31/04
Outputs
Our study includes an experimental component using Particle Image Velocimetry (PIV) to quantify the water motion generated by feeding fishes and a computational component to simulate water flow and forces during suction feeding. We collected the first ever data set of empirical measurements of the flow velocity patterns generated by the bluegill. PIV measurements and particle tracking show that water is drawn from all around the mouth. Fluid velocity decreases rapidly with distance from the mouth and is only significant (less than 5 percent mouth speed) within roughly 1 mouth diameter of the fish. After scaling of the velocity field based on size of the mouth opening and the measured fluid speed at a fixed position, the measured velocity profiles for all feedings are very similar to one another so that a functional relationship for the magnitude of fluid speed as a function of distance from the predator mouth is presented and shown to be generally true over the range
of kinematic variables tested. This relationship is descriptive of the velocity field both along the centerline of the fish and along transects lying at an angle to the centerline within both the mid-sagittal and frontal plane. Comparison of the time resolved fluid velocity measurements to gape kinematics demonstrate that peak fluid speed occurs simultaneously with 95 percent of peak gape, showing that the bluegill nearly simultaneously maximizes both the generated forces and size of the region over which these forces act. The magnitude of peak fluid speed during each strike decreases as a function of increasing time to peak gape (variance explained is 87 percent), demonstrating a strong relationship between kinematics and maximum generated flow speed. We measured the fluid mechanical effects of swimming (ram) on suction performance during prey capture. Suction performance can be measured as the maximum fluid speed of the water entering the mouth during feeding. We quantified the
effects of ram on suction performance as well as the spatial patterns of flow entering the mouth of suction feeding bluegill sunfish. Using PIV and high-speed video, we observed the flow in front of the mouth of three fish using a vertical laser sheet positioned on the mid-sagittal plane of the fish. We quantified the maximum fluid speed (measured at a distance in front of the mouth equal to one half of the maximum mouth diameter), the degree of focusing of water entering the mouth, and the shape of the ingested volume of water. Ram speed in 41 feeding sequences, measured at the time of maximum gape, ranged between 0 and 25 cm per second and the ratio of ram speed to fluid speed ranged from 0.1 percent to 19.1 percent. Ram speed did not significantly affect peak fluid speed but with an increase in ram speed the degree of focusing of water entering the mouth increased significantly, and the shape of the ingested volume of water became more elongate and narrow. The implication of this
is that suction feeders that employ ram of between 0 percent and 20 percent of fluid speeds sacrifice little in terms of the fluid speeds they generate and that ram speed enhances the total closing speed of the predator.
Impacts
Information on the ability of fish predators to capture prey by suction feeding will help us characterize the capacity of introduced sunfishes, like bluegill and largemouth bass, to adapt to the novel prey resources encountered in California's waters. Our research is permitting a precise description of how species differ in their mechanical ability to extract aquatic prey from the environment, a task that differs considerably from feeding in terrestrial systems. Understanding the feeding abilities of native and introduced species will give researchers a solid foundation for evaluating the role of competitive feeding interactions in determining the ability of introduced species to become established.
Publications
- No publications reported this period
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Progress 01/01/03 to 12/31/03
Outputs
Understanding the abilities of animals to make use of alternative prey resources can be a key to gaining insights into the success of introduced species and to understanding the outcome of competitive interactions with native animals. A potential key to understanding species interactions is to identify the functional basis of differences in the ability of species to make use of various environmental resources. In an attempt to better understand the interactions between native and non-native centrarchid fishes in California freshwaters we are studying feeding mechanics and their potential for feeding ecology in species of this fish family. This year we began a new NSF grant to study fluid mechanics of suction feeding in centrarchids. We have several projects that are ongoing. We are continuing our work computational fluid dynamics to simulate water flow and forces during suction feeding. We are now moving into using this as the basis for predictions that we will test
with Digital Particle Image Velocimetry, a method that permits direct measurement of fluid motion around feeding fishes. We will use this laboratory technology to study feeding abilities in several centrarchid species. A second new project involves the development of a musculo-skeletal model of suction feeding performance that is design ed to provide a direct interpretation for the differences between species in jaw design. We have tested this model by making morphological measurements on specimens that suction pressures were measured from and have found that it explains over 80 percent of the variation among fish and species in peak suction pressure performance. The model is based on the physiological cross-sectional area of the feeding muscles and their mechanical advantage in expanding the mouth cavity. We find support for our thesis that species trade off suction pressure capacity, which determines the peak flow velocities that are generated during suction feeding, for the rate of
volume expansion. This model is proving to be a useful complement to the fluid mechanical approach and have allowed us to estimate that the Sacramento Perch, the only native centrarchid is intermediate in feeding abilities among members of this family. This may account for reduced performance in the face of species with more specialized feeding mechanics, such as the bluegill and largemouth bass that appear to be the species that are most successful invaders of California waterways.
Impacts
Knowing the ability of fish predators to capture prey by suction feeding will show the capacity of introduced sunfishes to adapt to the novel prey resources in California waters. Understanding the feeding abilities of native and introduced species gives a framework for evaluating the role of competitive trophic interactions in determining the ability of introduced species to become established.
Publications
- Ferry-Graham, L.A., P.C. Wainwright and G.V. Lauder. 2003. Quantification of flow during suction feeding in bluegill sunfish. Zoology 106:159-168.
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Progress 01/01/02 to 12/31/02
Outputs
Understanding the abilities of animals to make use of alternative prey resources can be a key to gaining insights into the success of introduced species and to understanding the outcome of competitive interactions with native animals. In laboratory studies of feeding performance in sunfishes of the Family Centrachidae we used a combination of high-speed video, ultra-sound and pressure recordings and found that the traditional metric of suction feeding ability fails to characterize variation in suction pressure or complex jaw kinematics. We have developed alternative metrics of suction feeding performance based on pressure and induced water velocity that we are now using in comparative studies of several sunfish species that have been introduced into California waters. In a parallel study we developed a computational fluid dynamics computer program that simulates the water flows that are generated during suction feeding and permits calculations of forces that are
exerted on prey items. This model has provided two key results. First, it identifies a major advantage of jaw protrusion (a common behavior seen in most fishes) in moving the mouth opening out away from the fish body during suction generation. Because feeding fish generate a bow wave with their body when they suction feed, jaw protrusion induces hydrodynamic benefits by escaping the reversed water flow in the bow wave. This effect permits higher net suction flows in a fish that protrudes the jaws than one that can not. Second, the model indicates that the most important forces exerted on prey are from acceleration reaction, rather than drag, and implies that the most significant mechanical component of suction feeding is the acceleration of the water, rather than peak velocity as has been assumed previously. Our studies provide the groundwork for comparative interpretations of suction feeding performance, which is the focus of future studies. These studies will be conducted on several
introduced species and the one native member of the Centrarchidae, the Sacramento perch.
Impacts
Knowing the ability of fish predators to capture prey by suction feeding characterizes the capacity of introduced sunfishes to adapt to the novel prey resources encountered in California's waters. Understanding the feeding abilities of native and introduced species helps to evaluate the role of competitive trophic interactions in determining the ability of introduced species to become established.
Publications
- Ferry-Graham, L. A., D. I. Bolnick and P. C. Wainwright. 2002. Using functional morphology to examine the ecology and evolution of specialization. Journal of Integrative and Comparative Biology 42:265-277.
- Sanford, C. P. J. and P. C. Wainwright. 2002. Use of sonomicrometry demonstrates link between prey capture kinematics and suction pressure in largemouth bass. Journal of Experimental Biology 205:3445-3457.
- Svanback, R., P. C. Wainwright and L. A. Ferry-Graham. 2003. Linking cranial kinematics, buccal pressure and suction feeding performance in largemouth bass. Physiological and Biochemical Zoology. In Press.
- Ferry-Graham, L. A. and P. C. Wainwright. 2003. Evaluating suction feeding performance in fishes: Implications for evolutionary diversification. In (V. Bells, Ed.) BIOMECHANICS IN EVOLUTION. BIOS, Oxford. In Press.
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Progress 01/01/01 to 12/31/01
Outputs
My laboratory has pursued two major lines of research on the biomechanics and evolution of feeding in the freshwater fish family Centrarchidae. This group includes one species endemic to California, the Sacramento Perch, whose range has become greatly reduced over the last century. It appears in many instances that the Sacramento Perch is displaced by introduced species of the family, such as the Largemouth Bass, Bluegill and Green Sunfish. We are studying the mechanisms whereby these species may influence Sacramento Perch, specifically with regard to the possibility that differences in the functional capacities of the feeding mechanisms may influence competitive interactions. We are studying the systematics of this group as well as the feeding mechanisms and ecology of species relevant to this problem. To establish a baseline for comparative work, we have focused on the Largemouth Bass. A major study has been concluded in which we examined statistically the
relationship between suction feeding performance in this species, suction pressure measured inside the mouth cavity and kinematic patterns of motion as determined with high-speed video recordings of prey capture events. Large sample sizes (greater than 250 feeding events) were analyzed with high speed video (500 fps) in this project. The results show that while kinematic parameters account for variation in suction pressure, neither kinematics or pressure adequately account for feeding performance measures such as the distance from which prey are sucked into the mouth. Our second project is a major systematic analysis of the Centrarchidae. In spite of the prominence of this family in American life and the fish communities of our freshwater systems, the evolutionary relationships of the group are poorly known. We have sequenced two mitochondrial genes and one nuclear locus in all 32 species. This data set resolves relationships quite well in the group and we will publish t his once we
add data from a second nuclear locus. Three major groups are identified: a Micropterus group (the basses), a Pomoxis group (crappies and relatives, including the Sacramento Perch) and the Lepomis group (the sunfishes). Higher level relationships are resolved with all but five nodes receiving bootstrap support above 70 percent.
Impacts
In order to understand how introduced centrarchid fishes might impact the native Sacramento Perch we are trying to learn what limits their feeding performance. We will determine if the introduced fish perform better because they are better at exploiting prey. Understanding why introduced species have the impact they do is a key to generalizing our understanding of a very general problem.
Publications
- No publications reported this period
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Progress 10/01/00 to 12/31/00
Outputs
Since beginning my Agricultural Station project in April of 2000, my laboratory has pursued two major lines of research on the biomechanics and evolution of feeding in the freshwater fish family Centrarchidae. This group includes one species endemic to California, the Sacramento Perch, whose range has become greatly reduced over the last century. Interestingly, it appears in many instances that the Sacramento Perch is displaced by introduced species of the family, such as the Largemouth Bass, Bluegill and Green Sunfish. We are studying the mechanisms whereby these species may influence Sacramento Perch, specifically with regard to the possibility that differences in the functional capacities of the feeding mechanisms may influence competitive interactions. Our first line of research in this project has been to evaluate several basic mechanical features of the feeding mechanism in the native and introduced centrarchids. To establish a baseline for comparative work, we
have focused on the Largemouth Bass. A major preliminary study has been conducted in which we examined statistically the relationship between suction feeding performance in this species, suction pressure measured inside the mouth cavity and kinematic patterns of motion as determined with high-speed video recordings of prey capture events. Exceptionally large sample sizes were obtained in this project over 45 feeding sequences per fish that permitted considerable statistically power in the analyses. The results overturn existing ideas about the mechanistic link between fish feeding performance, suction pressure and jaw kinematics. We found an excellent ability to predict the magnitude of suction pressure with kinematic variables, and recovered over 80 percent of variation in pressure with three-variable multiple regression model. Most surprisingly, we were unable to explain significant amounts of variation in suction performance with either pressure or jaw kinematics. Thus, we found
that there was no relationship between the kinematics of prey capture or the magnitude of suction pressure and the distance over which Bass were able to draw prey into their mouths. Our second project has begun with a major systematic analysis of the Centrarchidae. In spite of the prominence of this family in American life and the fish communities of our freshwater systems, the evolutionary relationships of the group are poorly known. Our strategy has been to use DNA sequence data from four genes, three of which are from the mitochondrial genome and one nuclear gene. Thus far, we have sequenced segments of the ribosomal s gene consisting of about 1000 base pairs in 17 of the 32 species in this family. This data set shows excellent promise for resolving relationships in the group. Three major groups are identified: a Micropterus group (the basses), a Pomoxis group (crappies and relatives, including the Sacramento Perch) and the Lepomis group (the sunfishes). Higher level relationships
are resolved with all but five nodes receiving bootstrap support above 70 percent.
Impacts
By direct measurements of flexibility of the nervous system in controlling prey capture behavior by centrarchid fishes, we will compare feeding adaptability and test the hypothesis that success of introduced species in California is associated with differences between the Sacramento Perch and other centrarchids in feeding performance. This should assist in developing informed management strategies.
Publications
- No publications reported this period
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