Significant differential gene duplication without ancestral tetraploidy in a genus of mexican fish

A comparison of the protein products of 20–25 structural gene loci among the known species of the goodeid fish genus Skiffia suggests that at least 4 loci (16–20%) have undergone species-specific duplications (or, in 1 case, apparent loss) during the evolution of the genus. The species are clearly diploids, and the data therefore indicate that even a large proportion of differentially duplicated loci within a group of related fish species is not critical evidence of common tetraploid ancestry. Differential duplication of structural gene loci may be an important component of the genetic differences that separate congeneric conventional diploid species.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42725/1/18_2005_Article_BF01953797.pd

Pervasive gene flow across critical habitat for four narrowly endemic, sympatric taxa

1. We studied genetic variation in four endangered animal taxa in the largest freshwater spring complex in the southwestern U.S.A., Comal Springs (TX): Eurycea salamanders, Heterelmis riffle beetles, Stygobromus amphipods and Stygoparnus dryopid beetles. They inhabit a spring complex with nearly stable conditions, which is threatened by climate change and aquifer withdrawals. The four taxa vary in their habitat affinities and body sizes. 2. We used genotyping‐by‐sequencing to obtain hundreds to thousands of genetic markers to accurately infer the demographic history of the taxa. We used approximate Bayesian computation to test models of gene flow and compare the results among taxa. We also looked for evidence that would suggest local adaptation within the spring complex. 3. An island model (equal gene flow among all subpopulations) was the most probable of the five models tested, and all four taxa had high migration rate estimates. 4. Small numbers of single nucleotide polymorphisms (SNPs) in each taxon tested were associated with environmental conditions and provide some evidence for potential local adaptation to slightly variable conditions across habitat patches within Comal Springs. 5. We discuss how the results of this study can add to the habitat conservation plan for Comal Springs. If part of the spring system dries, migrants may recolonise from elsewhere within the spring complex. However, genetic variants affecting survival in particular habitat patches could be lost during such droughts