Detecting subtle variation in two cryptic primate families (tarsiidae and lorisidae) through morphology and genetics

Abstract

Cryptic species look morphologically similar but in fact are several different species lumped together. This is problematic as it hinders conservation efforts and makes it challenging to infer the evolutionary history of an organism. This dissertation research aims to improve our understanding of the evolution and variation of cryptic, nocturnal primates. Over 60% of primates are threatened with extinction, and many nocturnal species are poorly understood. Research aimed at elucidating species will help conserve them. To do so, I examined the multivariate craniodental allometry of the three genera of tarsiers. Tarsiers are small-bodied, nocturnal primates that have evolved to extreme-carnivorous niche. In order to see better at night their eyes have increased dramatically in size. Such evolution has led to minimal cranial variation among the three groups, despite millions of years of separation. Yet, two distinct groups were found through allometric analyses. Genetics is another tool that can discern the evolution and variation of cryptic species. The slow moving lorises of Asia and Africa appear morphologically similar, making it a challenge to determine their evolutionary history or variation. By using a multi-gene approach, I was able to determine the family is monophyletic with four distinct genera. Furthermore, analyses of a candidate gene that impacts coat color variation, found that the darker colored African genus has more mutations along its branch that result in amino acid changes than the vibrantly colored lorises in Asia. Such a result suggests that a transition to or a maintenance of a darker phenotype is conserved or that other genes besides this one candidate gene influence coat variation. Overall, I was able to find that through a variety of methods, it is possible to detect variation and the evolutionary history of cryptic species.