Yuan Deng:
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The tail is one of the most diverse traits in vertebrates. The polymorphous tails bring extraordinary functional diversity that enables vertebrates to obtain enhanced adaptability in the face of different environments. One of the most noticeable tail morphological variations is the tail length, which has been repeatedly reduced or lost during vertebrate evolution.
Among primates, macaques have the most extensive tail length variation, ranging from near absence to longer than their own body length. This widespread and independent reduction of tails raises the question of what genetic mechanism drove the convergent change in tail length. Most studies on tails so far have been focused on aspects of morphological evolution, while the genomic basis of tail shortening or loss remains puzzling.
Studying this repeated and rapid phenotypic loss would provide insight into the evolution of this morphology. Given that, my PhD thesis aims to explore the genetic basis underlying convergent tail shortening in multiple macaque lineages.
Using the newly sequenced macaque genomes, we are able for the first time to attempt to answer two questions: (1) what are the molecular mechanisms that lead to tail shortening in macaques, and what role do variants in coding and regulatory regions play in this process; (2) is there molecular convergence underlying convergent tail reduction in different macaque lineages, and if so, at what level of convergence?
Based on the investigation of different molecular variants, I suggest that gene losses, amino acid mutations, and regulatory elements divergence all contributed to the tail reduction for short-tailed macaques, but the regulatory elements divergence appears to play a more essential role as more candidates of regulatory elements divergence were found.
Moreover, the molecular convergence occurred more frequently at level of functional pathways. This finding is consistent with several reported convergent trait loss, such as limb loss in snakes and limbless lizards. My research provides a list of candidate genes and regulatory elements for convergent tail reduction in macaques and enhances our understanding of convergent phenotypic losses.