Progress 11/01/04 to 09/30/09
Outputs
We did preliminary studies of several projects to determine feasibility and assess interest of potential results. This includes: (1) We tested, in zebrafish, the hypothesized effect of the size of an embryo during development on the pigment pattern that ultimately develops. We completed preliminary work reducing the size of embryos through yolk removal experiments. These data suggest that development of the pigment pattern is correlated with size rather than age. (2) We did preliminary DNA sequencing of two genes (cyt b and ND2) to assess feasibility of doing a phylogenetic analysis of zebrafish and its relatives and determined this was not a feasible project given the difficulty of obtaining tissue from many other species and the poor state of alpha taxonomy in this group. (3) We are now using both morphological and molecular approaches to assess the hypothesized homology of the swimbladder of fishes and the lungs of tetrapods. We have done in situ hybridization for
one lung development gene in Xenopus and zebrafish as well as RT-PCR for zebrafish. We have done preliminary morphological studies using dissection, MRI and contrast radiography. (4) We are analyzing the phylogenetics of Australian skinks and investigating ecological influences on their diversification. We completed: (1) a study of inbreeding depression in zebrafish. We detected a significant effect of inbreeding on survival but no effect of food treatment on survival. We were able to demonstrate a second distinct class of deleterious allele over the early-acting, recessive lethals causing drastic abnormal morphology. This second class of milder alleles caused significant inbreeding depression, but in contrast to recessive lethals, were later-acting and morphologically cryptic. (2) A study demonstrating both a high frequency of alleles causing non-inflation or lack of the gas bladder in zebrafish in parallel to the high frequency of gas bladder loss across a broad phylogenetic array
of fishes. (3) A characterization of the basic ecology and diet of zebrafish and several related fishes in their natural habitat.
Impacts
(1) We demonstrated for the first time in vertebrates (zebrafish) that deleterious recessive alleles which segregate in a wild population belong to two sharply distinct classes: early-acting, morphologically overt, unconditional lethals and later-acting, morphologically cryptic, and presumably milder alleles. Understanding inbreeding depression is important for conservation genetics, evolutionary genetics and human genetics. (2) This is one of relatively few studies showing a parallel between intraspecific and interspecific variation. In addition, our results imply that developmental bias (constraint) and selection can act together rather than in opposition as is often supposed. (3) This is the first basic ecological data published for a number of these species, including zebrafish, even though the later has become an important model organism for developmental genetics.
Publications
- McCune, A. R. 2007. Comment on the current state of evolutionary biology and the challenges, opportunities of the near future. In: Allmon, W. and Grace-Kobas, L., eds. Darwin@Cornell: A Community Discusses Evolution, Creationism, and Intelligent Design. PRI Special Publication #30, 132 pp.
- Mittelbach, G., Schemske, D., Cornell, H., Allen, A., Brown, J., Bush, M., Harrison, S., Hurlbert, A., Knowlton, N., Lessios, H., McCain, C., McCune, A., McDade, L., McPeek, M., Near, T., Price, T., Ricklefs, R., Sax, D., Schluter, D., and Sobel, J. 2007. Evolution and the latitudinal diversity gradient: Speciation, extinction, and biogeography. Ecology Letters 10(4):315-331.
- Rabosky, D. L., Reid, J., Cowan, M. A., and Foulkes, J. 2007. Overdispersion of body size in Australian desert lizard communities at local scales only: no evidence for the Narcissus effect. Oecologia 154(3):561-570.
- McCune, A. R. 2006. Evolutionary novelty from a cellular and developmental perspective, review of The Plausibility of Life by M. W. Kirschner and J. C. Gerhart. American Paleontologist 14(2):38-40.
- Rabosky, D. L. 2006. LASER: A maximum likelihood toolkit for detecting temporal shifts in diversification rates from molecular phylogenies. Evolutionary Bioinformatics Online 2006:257-260.
- Rabosky, D. L. 2006. Likelihood methods for detecting temporal shifts in diversification rates. Evolution 60(6):1152-1164.
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Progress 01/01/06 to 12/31/06
Outputs
This year we worked on a variety of new projects having to do with the evolution of fishes. (1) We are testing, in zebra fish, the hypothesized effect of the size of an embryo during development on the pigment pattern that ultimately develops. We have completed preliminary work reducing the size of embryos through yolk removal experiments. These data suggest that development of the pigment pattern is correlated with size rather than age. We have attempted, but not yet been successful, at increasing the size of embryos. (2) We are using both morphological and molecular approaches to assess the hypothesized homology of the gas bladder of actinopterygians and the lungs of sarcopterygians. We have done in situ hybridization for one lung development gene in Xenopus and are beginning to do same for zebra fish. (3) We are investigating the effects of substrate specificity on the genetic divergence among Lake Tanganyikan endemic cichlids in comparison with Lake Tanganyika
gastropods living in the same habitats. Preliminary data suggest that non-preferred habitat, even over relatively small distances, can be a barrier to gene flow. (4) We are analyzing the phylogenetics of Australian skinks and investigating ecological influences on their diversification.
Impacts
(1) We demonstrated for the first time in vertebrates (zebra fish) that deleterious recessive alleles which segregate in a wild population belong to two sharply distinct classes: early-acting, morphologically overt, unconditional lethals and later-acting, morphologically cryptic, and presumably milder alleles. Understanding inbreeding depression is important for conservation genetics, evolutionary genetics and human genetics. (2) This is one of relatively few studies showing a parallel between intraspecific and interspecific variation. In addition, our results imply that developmental bias (constraint) and selection can act together rather than in opposition as is often supposed. (3) This is the first basic ecological data published for a number of these species, including zebra fish, even though the later has become an important model organism for developmental genetics.
Publications
- McClure, M.M., McIntyre, P.B. and McCune, A.R. 2006. Notes on the natural diet and habitat of eight danionin fishes, including the zebrafish Danio rerio. Journal of Fish Biology 69(2):553-570.
- McCune, A.R. 2005. Insights from natural variation in Danio rerio. Integrative and Comparative Biology 45(6):1042.
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Progress 01/01/05 to 12/31/05
Outputs
This year we have started a variety of new projects having to do with the evolution of fishes: (1) We are testing, in zebra fish, the hypothesized effect of the size of an embryo during development on the pigment pattern that ultimately develops. (2) We are using both morphological and molecular approaches to assess the hypothesized homology of the gas bladder of fishes and the lung of sarcopterygians. (3) We are elucidating the genetic and morphological diversification among Lake Tanganyikan endemic cichlids in comparison with Lake Tanganyika gastropods living in the same habitats. (4) We are analyzing the pylogenetics and ecological influences on diversification in Australian skinks. Completed since the last reporting were the following: (1) A study of inbreeding depression in zebra fish. We detected a significant effect of inbreeding on survival but no effect of food treatment on survival. We were able to demonstrate a second distinct class of deleterious allele
over the early-acting, recessive lethals causing drastic abnormal morphology. This second class of milder alleles caused significant inbreeding depression but in contrast to recessive lethals, was later acting and morphologically cryptic. (2) A study demonstrating both a high frequency of alleles causing non-inflation or lack of the gas bladder in zebra fish in parallel to the high frequency of gas bladder loss across a broad phylogenetic array of fishes. (3) A characterization of the basic ecology and diet of zebra fish and several related fishes in their natural habitat.
Impacts
(1) We demonstrated for the first time in vertebrates (zebra fish) that deleterious recessive alleles which segregate in a wild population belong to two sharply distinct classes: early-acting, morphologically overt, unconditional lethals and later-acting, morphologically cryptic, and presumably milder alleles. Understanding inbreeding depression is important for conservation genetics, evolutionary genetics and human genetics. (2) This is one of relatively few studies showing a parallel between intraspecific and interspecific variation. In addition, our results imply that developmental bias (constraint) and selection can act together rather than in opposition as is often supposed. (3) This is the first basic ecological data published for a number of these species, including zebra fish, even though the later has become an important model organism for developmental genetics.
Publications
- No publications reported this period
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