Natural Resources, School of


Date of this Version



Lawry, K. M. (2015). Genetic and Morphological Variation in Ecuadorian Astroblepid Catfishes (Masters thesis). University of Nebraska, Lincoln.


A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Natural Resource Sciences, Under the Supervision of Professor Steven A. Thomas. Lincoln, Nebraska: May 2015

Copyright (c) 2015 Katherine M. Lawry


The Andean ichthyofauna remains a poorly understood component of Neotropical biodiversity, and stands in stark contrast to the lowland ichthyofauna in terms of number of species and range of distribution. The Climate Variability Hypothesis (CVH) predicts rapid turnover of species along elevational gradients in tropical climates, but it remains unclear whether stream fishes follow this pattern. Astroblepid catfishes represent a distinctive assemblage of species that inhabit high elevation streams throughout the Andes from Panama to Bolivia, and constitute the only native fish family present in the Ecuadorian highland region. In this research, population samples of Astroblepids collected throughout Ecuador’s Napo Province over a 1000m elevational gradient were designated a priori into groupings based on external morphological features. Groupings based on morphological features were tested using DNA barcode sequences of the mitochondrial gene cytochrome c oxidase subunit I (COI). Sequences were analyzed in a phylogenetic context using Neighbor Joining and Bayesian Inference of Phylogeny. Results of molecular analyses indicated COI barcode sequence divergence that confirmed morphological designations in 2 of 14 cases, suggested the presence of cryptic diversity in 6 of 14 cases, and failed to explain morphological variation in the remaining 6 of 14 cases. Morphological and molecular categorizations showed no trend with elevation or temperature. Further molecular investigation using nuclear genes may help to resolve discrepancies between analyses and failure to match with morphological designations, while broader geographic sampling may yield more consistent patterns of distribution.

Advisor: Steven A. Thomas

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