Laurie Jacob
Master student
Department of Biology
Laval University

Supervised by:

Steeve Côté (Regular member)

Research project description

Effects of paternal quality on offspring phenotypic traits and sex-ratio in mountain goats

Introduction: Parental traits are crucial in determining the phenotypic traits and sex-ratio of offspring. In mountain goats, a polygynous species where females generally give birth to one kid each year, maternal condition, which is estimated using age, mass, and social rank, exerts a strong influence on offspring traits and sex-ratio. Mothers in good condition, which are older, heavier, and dominant, usually produce heavier offspring and may adjust the sex of their progeny according to the adult sex-ratio in the population, which is not the case for poor condition mothers. As for maternal traits, paternal traits could also influence the phenotypic traits and sex-ratio of the progeny. In mountain goats, heavier fathers sire heavier sons but lighter daughters than lighter fathers. However, the combined effects of paternal traits indicating the quality of a father, such as their age, mass, social rank, and annual reproductive success, on the traits and sex-ratio of their offspring remains unknown. Objectives: The overall aim of this study is to assess how paternal quality, defined by their age, mass, social rank, and annual reproductive success, affects the phenotypic traits and sex-ratio of offspring sired by different fathers in mountain goats. More specifically, this project aims to assess 1) whether the age, mass, social rank, and annual reproductive success of a father influence the mass, survival, and reproductive success of its offspring, and 2) whether the age, mass, social rank, and annual reproductive success of a father affect the sex-ratio of its progeny. Since maternal condition and the adult sex-ratio in the population are known to influence offspring phenotypic traits and sex-ratio, they will also be considered to discriminate the effect of father identity among those of other factors.Study sites: The study area is located at Caw Ridge, in west-central Alberta. This alpine environment is located at an altitude of 1,750 to 2,170 m, and the habitat includes small cliffs, rocky slopes, vegetated areas of alpine tundra and a few patches of mature shrubs and trees. The mountain goat population occupying this habitat uses an area of around 28 km2 annually. This population has been monitored annually since 1989 and has varied between 30 and 164 individuals. Most of the population is marked, and new individuals are marked each year. A total of 484 individuals have been marked since the monitoring has begun, making it possible to track the survival of each individual during field observations.Material and methods: When individuals are captured for marking, their sex is ascertained, and an ear sample is taken for genetic analysis to determine kinship. These captures are generally carried out when the individuals reach one year of age. The captured individuals are weighed using spring scales, but non captured individuals can also be weighted using electronic platform scales. Behavioral observations are also carried out in the field and aggressive interactions between individuals are recorded to establish the social hierarchy of males and females separately. Genetic analyses are carried out using 28 polymorphic microsatellite markers already identified for mountain goats. Once paternity is established, the number and the sex-ratio of the offspring will be established for each father.Expected results: By highlighting the contribution of paternal quality to offspring phenotypic traits and sex-ratio in mountain goats, this study will provide a better understanding of the reproduction of this species sensitive to global warming. This knowledge will improve our understanding of the determinants of fitness among individuals and might unravel why some offspring have better survival and reproductive success than others. This research will also assess whether fathers influence the sex-ratio of their progeny, therefore contributing to the growing evidence of male contribution to sex-ratio determination. By taking maternal and populational effects into account, this project will allow to discriminate paternal effects from those of other factors to provide more representative results, which can rarely be done in the wild, especially with long-lived species.

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