Search PubMed⌕ Search

Biomedical subjects

C F Aquadro

Publications and source records attributed to C F Aquadro.

79 records · Page 5Linked to original sources
PubMed1982

Evolutionary genetics of birds. V. Genetic distances within Mimidae (mimic thrushes) and vireonidae (Vireos).

Genetic distances (D's) between five species within each of the families Mimidae and Vireonidae were estimated from frequencies of protein electromorphs at 23 loci. For three mimid species in the genus Toxostoma, D equals 0.084 (range, 0.069-0.104); and among three mimid genera, D equals 0.223 (0.167-0.278). These distances typify values previously reported in other birds at comparable levels of taxonomic recognition. In sharp contrast, the mean genetic distance among five congeneric species of Vireonidae is far higher, D = 0.360 (0.027-0.578). One possible explanation for these results is that Vireo species are considerably older, on the average, than are species of Toxostoma or than are members of several other avain genera assayed to date. Conventional thought about the origin and relative age of the Vireonidae appears compatible with this explanation. Although genetic distances in the Vireonidae are large by "avian standards," they remain modest or even small in comparison with distances between many nonavian vertebrate congeners. Results for the Mimidae and the Vireonidae are directly contrasted with genetic distances in well-known genera of Amphibia and Reptilia.

Animals↗
PubMed1982

An assessment of "hidden" heterogeneity within electromorphs at three enzyme loci in deer mice.

Allelic heterogeneity within protein electromorphs at three loci was examined in populations of deer mice (Peromyscus maniculatus) collected from five localities across North America. We used a variety of electrophoretic techniques (including several starch and acrylamide conditions, gel-sieving, and isoelectric focusing) plus heat denaturation. Of particular interest was the supernatant glutamate oxalate transaminase system (GOT-1; aspartate aminotransferase-1 of some authors), which under standard electrophoretic conditions had been shown to exhibit basically a two-allele polymorphism throughout the range of maniculatus. The use of all of the above techniques failed to uncover any additional variation for GOT-1 in these populations. Similarly, no new scorable variation was resolved at the essentially monomorphic malate dehydrogenase-1 locus by additional conditions of electrophoresis. In marked contrast to the results for the above two enzymes, the use of multiple conditions of electrophoresis resolved the 8 standard-condition electromorphs of esterase-1 into a total of 23 variants showing strong geographic differentiation in frequency. These 23 electromorphs were further divided into a total of 35 variants by thermal stability studies. However, the allelic nature of all of the thermal stability esterase variants remains to be documented. The results of this study, taken together with the remarkable geographic heterogeneity for this species in ecology, morphology, karyotype and mitochondrial DNA sequence, suggest that some form of balancing selection may be acting to maintain the GOT-1 polymorphism.

Animals↗
PubMed1981

Genetic divergence between rodent species assessed by using two-dimensional electrophoresis.

O'Farrell's technique of two-dimensional gel electrophoresis (2-DGE) has previously been applied to the study of intrapopulation genetic variation. This approach assays a larger, and in part nonoverlapping, cohort of protein encoding loci compared to conventional one-dimensional electrophoretic procedures (SGE) and has revealed substantially lower levels of mean heterozygosity. Here we extend this approach to analyze levels and patterns of genetic differentiation between species. We have used 2-DGE to compare an average of 189 polypeptides between six species of wild mice representing levels of evolutionary divergence ranging from different subspecies to different families. The magnitude of protein divergence estimated by 2-DGE was on the average only about one-half that predicted by SGE. This discrepancy may result from differences in sensitivities between the techniques or differences in the mean level of variation and divergence between the sets of loci assayed by the two methods. Nonetheless, the ranking of genetic distances by 2-DGE was identical to that by SGE. Thus, these results support the use of the simpler SGE techniques to estimate relative levels of genetic divergence.

Animals↗
PubMedDate not supplied

Mitochondrial DNA variation among the Drosophila athabasca semispecies and Drosophila affinis.

Morphology, allozymes, and levels of postreproductive isolation indicate that the semispecies of Drosophila athabasca are as recently diverged as typical populations within a Drosophila species. However, levels of behavioral isolation, divergence in male mating song, and divergence in X-chromosome inversions suggest a much more ancient divergence. In this article, we have examined mitochondrial DNA restriction site variation within and among the three semispecies. These data support the hypothesis that the three semispecies of Drosophila athabasca are at least as recently diverged as are typical populations within other species of Drosophila. Male mating song, behavioral isolation, and X-chromosome differences thus appear to have evolved very rapidly. In addition, hypothesized phylogenetic relationships of these three semispecies, based on our mtDNA data, are identical to those based on allozymes and chromosomal inversions. According to this phylogeny, recency of ancestry is not well correlated with levels of behavioral isolation, whereas patterns of sympatry and allopatry are. These patterns strongly implicate the action of selection in the rapid evolution of behavioral isolation and X-chromosome gene arrangement.

Animals↗