Graduation Semester and Year

2016

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Quantitative Biology

Department

Biology

First Advisor

Jonathan A Campbell

Abstract

The shape and size of vertebrates is shaped by adaptive processes and phylogenetic relationships, and constrained by mechanical and developmental constraints. We quantified the diversity of the skull using geometric morphometrics, studied the shape of the oral disc of tadpoles, constructed and corrected phylogenies of the Middle American Tree frogs, a monophyletic lineage with highly diverse shapes and sizes distributed in Central and North America, and temperate Eurasia. Four major clades are identified in the Middle American Tree frogs. We measured allometric effects and assessed the independence between the evolutionary history of the larval and the adult phenotype in two different evolutionary scales: along all the Middle American tree frogs, and within one genus of frogs (Plectrohyla) restricted to a small geographic area in the mountains in Nuclear central America. At least four major shifts towards large size are identified in four genera along the whole clade of Middle American Tree frogs. Within the genus Plectrohyla, three major independent shifts towards large size were identified. Correlation between shape and size has different degrees in each of the independent size shifts. Adult phenotype seems to be shaped in some cases by phylogenetic relationships, and in other cases by adaptive processes evidenced by convergence in skull shape. Attainment of large sizes permits shape diversification and limits the occurrence of only one clade of large species in each mountain region. Different clades of small generalist species inhabit together in all geographic areas of Middle America and show low phenotypic diversification. Larval phenotypic evolution can be completely independent from adult phenotypic evolution. Species of similar frogs can have different larval forms and presumably this partitions the niches during the larval phase under strong selective pressures. Mountain habitats show the largest diversity of Middle American tree frogs, and the evolution of larvae adapted to mountain stream is proposed as the key novel feature that permitted tree frogs to diversify along mountain regions in Middle America like no other clade has been able to. Adaptations to mountain streams have appeared in different ways and independently in different genera of tree frogs.

Keywords

Hylidae, Systematics, Geometric morphometrics, Tadpole

Disciplines

Biology | Life Sciences

Comments

Degree granted by The University of Texas at Arlington

Included in

Biology Commons

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