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Title: Social and reproductive behaviour of California sea lions (Zalophus californianus californianus) : insights from a molecular and behavioural approach
Author: Hernandez-Valazquez, Francisco Daniel.
ISNI:       0000 0001 3554 6351
Awarding Body: University of East Anglia
Current Institution: University of East Anglia
Date of Award: 2007
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This thesis examines the social and reproductive behaviour of California sea lions (Za/ophus califomianus) and their importance in species management. Genetic tools were developed for genetic analysis. I isolated and characterized nine microsatellite markers, and also characterized four loci from other species. Time allocation analysis was carried out as the basis for all behavioural components of this study. I found females trade-off time spent in aggression with time spent nursing, while males spent more in aggression at the end of the reproductive season than during the middle stages. Relatedness estimates for the adult population provided insights into unusual levels of male philopatry at the colony of Los Islotes. Almost half of the adult males sampled had at least one first-order relative, and the proportion grew to almost 70% when considering second-order relatives. It is possible that, despite the apparent lack of male dispersal, inbreeding avoidance, possibly through kin recognition, does not promote male dispersal but actively prevents mating among known close relatives, thus increasing the likelihood of male natal philopatry. Parentage analysis provided evidence of two parallel mating strategies in the population. Up to a third of the offspring in a year are sired by out-of-colony males. Since aquatic copulations require cooperation and male philopatry is high in this colony, results could indirectly point towards females choosing their mates. Peace-keeping behaviour of male California sea lions was, for the first time, put into a conflict-resolution a behaviour context. I found that at least 50% of the males exhibit this behaviour, although the duration of each bout is small. Males and females are likely to benefit from peace-keeping behaviour, although further research is required to determine their nature and magnitude. Geographical structuring within the Gulf of California population is highly likely and population size decreases may lead to fragmentation that could prove harmful. I suggest that the relevant IUCN specialist group categorises this population as "conservation dependent".
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available