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Title: A macroevolutionary study of tetrapod diversification
Author: Sahney, Sarda
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2013
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A large diversity of tetrapods - amphibians, reptiles, mammals and birds - populate this planet today, all of which share a common ancestor. Tetrapods show an exponential pattern of growth, punctuated by losses during major extinctions over the last 400 million years. Detailed study of three major evolutionary events and a macroscopic analysis to identify broad patterns helps us understand how vertebrates have evolved. expanded and diversified on land. After the evolution of tetrapods in the Devonian, a sparse record is present in the early Carboniferous, punctuated by a hiatus termed Ramer's Gap. Growing tetrapod diversity was impacted in the Late Pennsylvanian by the Carboniferous Rainforest Collapse of Euramerica. Changes in taxa, communities, and tTophic structure indicate that amphibian diversity stagnated in the drier climate while reptiles invaded empty habitats, explored new feeding strategies, and created endemic faunas. Reptiles continued to flourish until the Permian-Triassic Boundary extinction. Ecosystems were destroyed by a multi-pulse event, communities were restructured and though taxa recovered quickly, full ecological recovery occurred in the Late Triassic. Patterns of mass extinction and recovery have reoccurred throughout tetrapod history: large c1ades were wiped out, disaster taxa become widespread, animals possessing unique and advantageous adaptations thrived, and communities took many millions of years to recover. A macroevolutionary analysis supports the Court Jester model of diversification where external, abiotic elements have had a broader influence than the intrinsic, biotic factors of the Red Queen model. Tetrapod taxonomic and ecological diversity are strongly linked, having been driven at an increasing rate by the different tetrapod classes. The Court Jester is supported by the unrestricted taxonomic and ecological expansion of tetrapods, the ability of taxa to invade empty ecospace and rare catastrophic events which have devastated life.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available