Biochemical polymorphisms and phenetic relationships in rodents of the genusCtenomys from Southern Brazil

Abstract

Protein variation at 20 loci was analyzed by starch gel electrophoresis in population samples of Ctenomys flamarioni, C. torquatus, C. sp., and C. minutus collected in 25 localities of Southern Brazil. Results show that these four species exhibit higher levels of genetic variability (He = 0.11-0.17) than those reported for most other fossorial rodents. Estimates of similarity coefficients indicate that C. minutus and C. sp. (S = 0.91) are the closest species, while C. flamarioni (S = 0.77) is the most distant from the others. The data presented here support the hypothesis of a relatively recent disjunction of C. minutus from C. sp. Within-species similarity indices are of the same order of magnitude as those found between species. The relatively high levels of heterozygosity observed are not in accordance with the view that subterranean taxa should be less variable than aboveground species due to the uniformity of their environment.

Allozymic characterization and evolutionary relationships in the BrazilianAkodon cursor species group (Rodentia-Cricetidae)

“…The deviations were due to heterozygote deficiency. Similar results were also obtained in other reports on different species of rodents (Nevo, 1982;Zimmerman, 1988;Garcia et al, 1990;Moreira et al, 1991). According to Spiess (1977), many factors may create these deviations: (1) subdivision of populations, (2) presence of silent alleles, (3) preferential mating, and (4) selection against heterozygotes.…”

“…Such studies have already been made in Akodontini and other rodent groups (Apfelbaum and Blanco, 1984;Apfelbaum and Reig, 1989;Patton et al, 1989;Moreira et al, 1991).…”

Cytogenetics Status of Four Ctenomys Species in the South of Brazil

“…Moreira et al (1991) found 0.91 of Roger's genetic similarity based on 20 loci in biochemical polymorphism. The karyotypes show four different but related chromosomic pairs, while the two species are quite different in skull morphology based on a Discriminant Analysis of 20 skull characters (Freitas, 2001).…”

The Molecular Phylogenetics of Tuco-Tucos (genusCtenomys,Rodentia: Octodontidae) Suggests an Early Burst of Speciation

“…These prospects, however, are severely hampered by a lack of understanding of phylogenetic relationships among species. The genus has been characterized as being in a state of ''taxonomic chaos'' (Sage et al, 1986), though progress has been made in recent years in the study of several species groups using banded karyotypes (e.g., Gallardo, 1991;Ortells, 1995) or protein electrophoresis (Gallardo and Köhler, 1992;Gallardo and Palma, 1992;Moreira et al, 1991;Cook and Yates, 1994).…”