Population genetic consequences of mating systems and dispersal

Abstract

Understanding the drivers of genetic differentiation in natural populations is one of the fundamental goals in evolutionary biology. The maintenance of genetic diversity is essential for the persistence of species and it may require dispersal between populations. In this dissertation I focus on dispersal, mating systems, and their population genetic consequences in evolutionary and conservation biology. Using shorebirds (plovers, sandpipers and allies) that exhibit an unusual diversity in mating system, I explore the relationships between dispersal, mating systems, and genetic diversity from the chromosome, to a macro-evolutionary scale. First, my dissertation shows that contrary to the expectation, intense sexual selection can reduce rather than increase population differentiation, by increasing the dispersal of individuals between populations to increase their mate access. Second, I show that with intense sexual selection on females, the genetic diversity of the Z chromosome is increased and the opportunity for genetic drift is reduced. The latter finding contrasts with previous work that has been restricted to polygynous or monogamous mating systems, and demonstrates that the genetic consequences of mating systems may depend on both the direction and the intensity of sexual selection acting on males relative to females. Third, using demographic modelling, I found signals of population bottlenecks in a threatened shorebird, the snowy plover (Charadrius nivosus), and used complementary genetic markers to highlight subspecies for conservation prioritization. Fourth, by combining field and genetic data, I found signals of population expansion in the Madagascar jacana (Actophilornis albinucha), suggesting this vulnerable species has maintained genetic diversity, despite on-going habitat destruction. Taken together, my dissertation demonstrates that the consequences of mating systems are complex and may impact across several evolutionary scales. Future investigations should combine theoretical and empirical approaches using field and molecular data, to disentangle the mechanisms behind the relationship between mating systems, dispersal, and diversification.

Date of Award	1 May 2019
Original language	English
Awarding Institution	University of Bath
Supervisor	Tamas Szekely (Supervisor), Michael Bruford (Supervisor) & Clemens Kupper (Advisor)