Meeting Abstract
44.1 Saturday, Jan. 5 Morphological Analysis of Southeastern Clade Central Texas Spring and Cave Salamanders ROELKE, CE*; MEIK, JM; BENDIK, NF; GLUESENKAMP, AG; CHIPPINDALE, PT; The University of Texas at Arlington croelke@uta.edu
Neotenic salamanders from central Texas in the genus Eurycea exhibit a continuum of morphological variation. The extremes of this continuum are illustrated by the highly troglomorphic salamanders seen in some populations of E. tridentifera, and other populations which exhibit epigean (surface dwelling) morphological characteristics. Previous phylogenetic hypotheses for the group have been based largely on morphological characteristics. We measured ten characters of external morphology on over 170 salamanders representing the �Southeastern� clade of central Texas Eurycea. Principal Component Analysis and Discriminant Analysis were performed on these measures. Characters that greatly influenced the results of these analyses were eye diameter, head length, head width, and interocular distance. Distinct morphotypes were revealed, in many cases corresponding to individual populations, closely related populations, or geographically proximate populations. Epigean populations tend to cluster together in morphospace. By comparing the results of this multivariate morphological analysis with robust inferences about the phylogeny of the clade (based on molecular data), we can examine patterns of character evolution. Given that the central Texas Eurycea evolved from a transforming, surface dwelling salamander, epigean character suites are ancestral within the group. Our analysis suggests that troglomorphic character suites have evolved multiple times and that there are multiple distinct morphotypes that are considered troglomorphic. These results suggest that natural selection is strong in at least some habitats with regards to external morphology and that morphology alone is a poor indicator of phylogenetic relationships within the group, possibly because of the high level of homoplasy in the form of morphological convergence.
