Evolution of the Auditory Region Structures of the Extinct Ruminant Hoplitomeryx

Description du projet

L’évolution des ruminants à travers l’anatomie de l’oreille

La résolution des relations évolutives chez les ruminants, un groupe remarquablement diversifié comprenant les vaches, les cerfs et les moutons, a longtemps été entravée par des changements morphologiques rapides. La région de l’oreille, dont on pense qu’elle évolue lentement, pourrait apporter des éclaircissements à ce sujet. Son évolution typique chez des espèces étroitement apparentées, notamment en réponse aux pressions écologiques, reste mal comprise. Avec le soutien du programme Actions Marie Skłodowska-Curie, le projet EARSHOT entend quantifier la variation de la région de l’oreille et les taux d’évolution chez les ruminants insulaires et continentaux, notamment en documentant pour la première fois l’anatomie de l’oreille d’un ruminant insulaire disparu. En développant et en appliquant des méthodes morphométriques géométriques avancées, EARSHOT va tester diverses hypothèses concernant l’évolution des mammifères tout en établissant de nouvelles normes pour son étude.

Objectif

Morphological data are crucial to resolving evolutionary relationships, but rapid evolution can overwrite this information. Because of this, the evolutionary relationships of ruminants (e.g. cows, sheep, and deer), one of the most diverse groups of mammals, are poorly understood. Ear region data may aid in resolving these relationships because it is thought to evolve slowly. Yet little is known about how this region evolves among closely related species, or how ecological factors influence its evolution. Data from a pilot study I conducted and from Hoplitomeryx, an extinct insular ruminant, highlight how little is known about the variation and evolutionary rates of the ear region, bringing current dogma into question. In EARSHOT, I will combine my knowledge of CT data and the ear with training in geometric morphometrics (GMM) and ruminants. This will enable me to quantify variation and evolutionary rates of the ear region using a dataset of island and mainland ruminants, answering whether ear region structures are truly all slow evolving with little variation. I will document the morphology of Hoplitomeryx, producing the first description of the ear region of an island endemic, and develop a novel GMM protocol for the petrosal, a major ear region structure. I will also develop a new GMM method to compare separate structures. My GMM protocols will set a new standard for quantifying and comparing variation, and my findings will be applicable to the study of mammal evolutionary relationships and variation and evolutionary rates across vertebrates. My research uses novel methods to test assumptions about evolution, and I will develop my GMM skills, add to my CT knowledge, and broaden my taxonomic expertise, enabling me to strengthen my research program. These skills, plus the teaching, mentorship, management, and science communication that I will learn, will provide me with the toolkit I need to become a tenured researcher and instructor at an academic institution.