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Title: Dispersal and reproductive competition in mammals
Author: Hobson, L.
ISNI:       0000 0004 6422 568X
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2017
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Dispersal behaviour (DB) and reproductive competition (RC) are interrelated factors that are key in many evolutionary and ecological processes. DB dictates the density, dynamics and composition of populations. DB thus affects, for example, the risk of kin competition, level of RC and population longevity. RC impacts behaviours such as mating strategies and tolerance for conspecifics, which can affect DB. Despite the importance of DB and RC, their association and their causes and consequences are poorly understood. This thesis explores how mating system, competitor relatedness and maternal effects influence DB and RC in mammals. Local mate and resource competition are ultimate causes of DB. Both are also key components of RC, and are associated with mating system. Particular mating systems are thought to cause a given dispersal pattern. Here, I explore hypothesised links between mating system and DB in mammals using a comparative approach. There was little evidence to support the proposed links between mating system and DB, excepting an association between unbiased dispersal and monogamy. Intrasexual kin competition may influence both DB and investment in RC. In mammals, males usually compete for mates, and competition may occur before and/or after copulation. Males are expected to invest relatively less in RC when competing primarily among kin. Using phylogenetic analyses, I found evidence that ejaculate investment was greater when males are more likely to compete with kin, and that males may avoid kin when the level of precopulatory competition becomes high. Population density is positively correlated with RC and dispersal propensity, and may cause maternal effects on many traits. I use bank voles (Myodes glareolus) as an experimental model to investigate maternal effects on traits related to DB and RC in mammals. I manipulated perception of population density under laboratory conditions by exposing adult females to social cues indicating 'high' or 'low' levels of same-sex conspecifics. In litters produced by these females, I found evidence of a maternal effect on sex ratio, but not litter size, pup growth rate or offspring weaning mass. Males born in litters produced females exposed to 'high' levels of social cues had higher rates of daily sperm production and larger epididymides, consistent with an adaptive maternal effect on reproductive traits. However, there was no evidence for a maternal effect on DB. By providing new insights into associations between DB and RC in mammals, the work presented herein has potentially far-reaching impacts in evolutionary ecology, and provides a basis for future advances in understanding patterns of dispersal across diverse species.
Supervisor: Stockley, P. ; Hurst, J. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral