Andre Ngo

The Phylogenetic Relationships of the Chinese and Vietnamese Waterfall frogs of the genus Amolops

Ranid frogs of the genus Amolops occur in Southeast Asia and are typically found near waterfalls. Their phylogenetic relationships have not been resolved. We include 2,213 aligned nucleotide sites of the 12S, 16S and tRNA(val) gene regions of the mitochondrial DNA genome from 43 individuals of Chinese and Vietnamese Amotops, Huia, Hylarana, Meristogenys, Odorrana and Rana. The outgroup species were from the genera Chaparana, Limnonectes, Nanorana, and Paa. The data were analyzed within the framework of a refutationist philosophy using maximum parsimony. Four clades of waterfall frogs were resolved. Meristogenys was not resolved as the sister group to either Huia nor Amolops. The hypothesis Of evolutionary relationships placed Amolops chapaensis and Huia nasica in the genus Odorrana.

Genealogy and Demographic History of a Widespread Amphibian throughout Indochina

Relatively little is known about spatial patterns of cryptic diversity in tropical species and the processes that generate them. Few studies examine the geographic distribution of genetic lineages in Southeast Asia, an area hypothesized to harbor substantial cryptic diversity. We investigated the evolutionary history of Asian tree frogs of the Polypedates leucomystax complex (n = 172) based on 1800 bp of the mtDNA genes ND1 and cytochrome b and tested hypotheses pertaining to climate, geology, and dispersal patterns. Analyses revealed substantial genetic diversity and lineage divergence throughout the region with evidence for widespread sympatric lineages and a general north versus south clustering. Relaxed molecular clock analysis and tests for demographic expansion identified an initial cladogenesis during the Miocene with subsequent Plio-Pleistocene diversification, with the former corresponding to periods of increased aridity and the onset of monsoonal weather systems. Rates of diversification were relatively constant until the Early Pleistocene when rates increased exponentially. We found equivocal evidence for isolation-by-distance and a potential role of some landscape features as partial barriers to dispersal. Finally, our analyses showed that divergence between insular and mainland populations occurred before Homo sapiens colonized Southeast Asia, suggesting that historical human-mediated dispersal did not drive insular diversification. Our results suggested that demographic expansion in the Late Pleistocene resulted in widespread sympatric lineages in the P. leucomystax complex throughout southern China and Indochina and further clarified the evolutionary history of lineages within P. leucomystax.

STR/microsatellite primers for the desert tortoise, Gopherus agassizii, and its congeners

The desert tortoise, Gopherus agassizii, is a threatened species native to the North American desert southwest and is recognized as having genetically distinct Mojave and Sonoran desert populations. The Mojave Desert population is federally listed as threatened under the Endangered Species Act and the Sonoran Desert population is fully protected under Mexican and United States state laws. We identified nine dinucleotide STR loci in the desert tortoise and tested their efficacy in 80 samples from both the Sonoran and Mojave deserts. One locus exhibited low allelic variation (4 alleles) while seven were highly variable (8–16 alleles). One locus exhibited a unique allele in congeners (G. flavomarginatus and G. berlandieri).

Reassessment of the phylogenetic relationships among Anodonta, Pyganodon, and Utterbackia (Bivalvia: Unionoida) using mutation coding of allozyme data

ABSTRACT The use of molecular markers has greatly increased our understanding of unionoid systematics. However, it is critical that their use in phylogenetic studies be conducted with the correct methodologies in order to ensure that the correct interpretations of evolutionary history are made. The phylogenetic relationships of a selection of Anodonta were investigated by Hoeh (1990), who found variation in 23 allozyme loci. These allozymes were coded using the presence/absence of alleles, yielding 67 characters used in a phylogenetic analysis. The resulting phylogeny was used as evidence to recommend the elevation of Pyganodon and Utterbackia to full generic status. Since the publication of Hoeh (1990) the coding of characters using the presence/absence of alleles has been shown to be invalid and has been superseded by mutation coding, with the locus as the character. The phylogenetic analysis of 20 characters, coded using mutation coding, yielded two equally parsimonious trees and an interpretation markedly different from that of Hoeh (1990). Both trees supported the monophyly of Pyganodon and Utterbackia. However, the genus Anodonta was paraphyletic with respect to both Pyganodon and Utterbackia. The one Eurasian species (Anodonta cygnea) was resolved as the sister of the remaining ingroup taxa, including Pyganodon, Utterbackia, and the North American Anodonta. These findings lead to a taxonomic problem, requiring further phylogenetic analysis of the Anodontinae. In order to test the phylogenetic hypotheses presented herein, we strongly recommend the construction of a phylogeny for all anodontine taxa using a combination of mitochondrial and nuclear DNA sequences.