Carla Ann Hass

Molecular insights into the relationships and biogeography of West Indian anoline lizards

Abstract The realization that the present day positions of continents and island arcs are a result of continental drift led to the proposal that the extant West Indian fauna reflect an ancient (Cretaceous) land connection between the proto-Antilles and North and South America. Movements of the Antillean islands throughout the Cenozoic are hypothesized to have further fragmented the fauna present on the proto-Antilles when it separated from the mainland 70–80 million years ago. This proposed vicariant origin of the West Indian fauna challenged the previous theory that some or most of the fauna arrived in the Antilles by overwater dispersal from mainland soruces. The virtual absence of appropriate fossils in the West Indies has hampered testing these alternative hypotheses for the origin of the present day West Indian fauna. We present evidence from two types of molecular data, one providing indirect estimates of amino acid sequence divergence for the protein serum albumin, and the other direct DNA sequence information from a mitochondrial ribosomal RNA gene. Our new data provide insights into the origin and relationships of two enigmatic lizard genera, Chamaeleolis and Chamaelinorops , and suggest they are recent derivatives within the genus Anolis . These data, along with molecular data presented elsewhere, strongly implicate an origin by overwater dispersal for most of the Antillean vertebrate fauna.

Crocodilian evolution: insights from immunological data.

The quantitative immunological technique of microcomplement fixation was used to examine serum albumin evolution among members of the order Crocodylia. The cross-reactivity of the albumin antisera and antigens employed in this study had been examined previously using the qualitative technique of immunodiffusion. The phylogenetic conclusions derived from these two data sets are highly congruent, including support of the families Alligatoridae and Crocodylidae, with the placement of Gavialis as the sister taxon of Tomistoma. Both methods provide similar information on the relative amounts of amino acid sequence divergence between albumin molecules; however, the data obtained from microcomplement fixation comparisons are more discriminating than those derived from immunodiffusion. The estimated divergence times within the Crocodylia derived from the fossil record are examined in light of divergence times predicted by the microcomplement fixation-based albumin clock. The traditional phylogenetic placement of Gavialis outside the remaining extant crocodilians is inconsistent with all molecular data sets and we suggest that a careful reexamination of both the extant and the fossil morphological data is warranted.

Divergent Lineages within the Bufo margaritifera Complex (Amphibia: Anura; Bufonidae) Revealed by Albumin Immunology'

The toads belonging to the Bufo margaritifera complex (Amphibia: Anura; Bufonidae) are widely distributed in the Neotropics. A molecular analysis, using the quantitative immunological technique of micro-complement fixation, assessed the degree of divergence in a plasma protein, serum albumin, among representative Central and South American toads currently placed in this complex. This analysis revealed a surprisingly large amount of genetic diversity. Comparisons of estimates of albumin sequence evolution in representatives of the Bufo margaritifera complex from 32 localities in one central and seven South American countries indicate that this complex indudes more than three lineages that are very distinct genetically but show relatively little morphological variation. The degree of albumin divergence implies that some of these lineages have been isolated for at least 30 million years. This study also suggests that the amount of genetic diversity within other Amazonian species or species groups could be substantial.

Concurrent speciation in the eastern woodland salamanders (Genus Plethodon): DNA sequences of the complete albumin nuclear and partial mitochondrial 12s genes

Salamanders of the North American plethodontid genus Plethodon are important model organisms in a variety of studies that depend on a phylogenetic framework (e.g., chemical communication, ecological competition, life histories, hybridization, and speciation), and consequently their systematics has been intensively investigated over several decades. Nevertheless, we lack a synthesis of relationships among the species. In the analyses reported here we use new DNA sequence data from the complete nuclear albumin gene (1818 bp) and the 12s mitochondrial gene (355 bp), as well as published data for four other genes (Wiens et al., 2006), up to a total of 6989 bp, to infer relationships. We relate these results to past systematic work based on morphology, allozymes, and DNA sequences. Although basal relationships show a strong consensus across studies, many terminal relationships remain in flux despite substantial sequencing and other molecular and morphological studies. This systematic instability appears to be a consequence of contemporaneous bursts of speciation in the late Miocene and Pliocene, yielding many closely related extant species in each of the four eastern species groups. Therefore we conclude that many relationships are likely to remain poorly resolved in the face of additional sequencing efforts. On the other hand, the current classification of the 45 eastern species into four species groups is supported. The Plethodon cinereus group (10 species) is the sister group to the clade comprising the other three groups, but these latter groups (Plethodon glutinosus [28 species], Plethodon welleri [5 species], and Plethodon wehrlei [2 species]) probably diverged from each other at approximately the same time.

Physiological color change in snakes

genus Japalura (Lacertilia: Agamidae) found from Taiwan. Q. J. Taiwan Mus. 29:153-189. Lou, S.-K., AND J.-Y. LIN. 1983. Biochemical systematics of the genus Japalura (Sauria: Agamidae) in Taiwan. Bull. Inst. Zool., Academia Sinica 22:91104. OTA, H. 1988. Karyotypic differentiation in an agamid lizard, Japalura swinhonis swinhonis. Experientia 44:66-68. 1989a. Japalura brevipes Gressitt (Agamidae: Reptilia), a valid species from a high altitude area of Taiwan. Herpetologica. In press. 1989b. Re-evaluation of the status of Japalura mitsukurii Stejneger 1898 (Agamidae: Reptilia). Amphibia-Reptilia. In press. WERMUT, H. 1967. Liste der rezenten Amphibien und Reptilien. In R. Mertens, W. Hennig, and H. Wermuth (eds.), Das Tierreich, Vol. 86. Walter de Gruyter & Co., Berlin.

Relationships among the Eastern Plethodon: Evidence from Immunology

Relationships among North American plethodontid salamanders have been the subject of numerous molecular studies. In particular, immunological investigations of albumin evolution using the quantitative technique of micro-complement fixation have provided insights into relationships between the genera Ensatina and Plethodon, as well as within Plethodon. However, examination of relationships within eastern Plethodon has been hindered due to lack of antisera from a representative of each species group. An antiserum to albumin from P. wehrlei (wehrlei group) was produced and compared to all available Plethodon antigens. With this antiserum, all currently recognized species groups of eastern Plethodon (glutinosus, cinereus, welleri, and wehrlei) are now represented in a reciprocal matrix of im- munological distance values. Phylogenetic trees derived from these data indicate that the welleri and glutinosus groups are sister taxa, and cluster with the wehrlei group; the cinereus group is the most distant within the eastern Plethodon. This topology conflicts with that based on electrophoretic and morphological data, which suggest that the glutinosus and wehrlei groups are sister taxa. A close examination of the albumin immunological data shows that the rate of albumin evolution within eastern Plethodon has been variable, and therefore these data may be less reliable for phylogenetic reconstruction in this taxon.

SNAKE RELATIONSHIPS REVEALED BY SLOWLY-EVOLVING PROTEINS: FURTHER ANALYSIS AND A REPLY

A reanalysis of our allozyme data (Dowling et al., 1996) for four slowly-evolving loci in 215 species of snakes by Buckley et al. (2000) concluded that because of ties in genetic distances our published UPGMA tree had “little resolution, indicating that these data are highly ambiguous regarding higher-level snake phylogeny.” They also concluded that “the high degree of resolution in the published phenogram is an analytical artifact.” Our study was intended to obtain information on lower-level relationships for the snake species that we had available, and it provided support for some current hypotheses of snake relationships at that level. Buckley et al. (2000) reached their conclusions because in their analysis they used only strict consensus trees and did not randomize the order of their input data. By randomizing data input order and using a majority-rule consensus tree, we show that there is considerable phylogenetic signal in our data.