Browsing by Subject "inbreeding"

Bryophytes, by their haploid dominant life cycle, possess several unique qualities ideal for study of mating patterns. In particular, the possibility of intragametophytic selfing in some species, and the vegetative propagation of gametes allow for a unique window into the haploid stage that is intractable in other groups. Despite these advantages, there have been relatively few studies on mating patterns bryophytes in natural populations. Sphagnum (peatmoss) is an excellent case study in the interactions between sexual condition, ecology, and mating patterns. In the first Chapter, we use microsatellites to characterize the genetic diversity and mating patterns in fourteen species of Sphagnum, diverse in sexual condition (separate vs combined sexes in the haploid stage) and ecology (microhabitat variance along the water table). We find that genetic diversity and mating patterns are related only in species with separate sexes, that sexual condition and ecology have interacting effects on inbreeding coefficients, and that inbreeding depression is not a common phenomenon in Sphagnum. In the second Chapter, we conduct an intensive survey of one population of Sphagnum macrophyllum, to detect whether variance in haploid fecundity and mating success is related to diploid fitness. We find a relationship between mating success and fecundity (a signal of sexual selection), and fitness of the diploid generation is connected to the parentage of the haploid generation. Finally, in Chapter 3 we use phylogenetic comparative methods to track the phylogenetic signal in microhabitat preference in Sphagnum. We find extremely fast rates of evolution along the micronutrient gradient, but high phylogenetic signal along a hydrological gradient. Given that Sphagnum species living high above the water table have reduced water availability, phylogenetic signal in the hydrological gradient has macroevolutionary implications for mating systems in Sphagnum.

The deleterious effects of inbreeding have been well-documented in both captive and wild populations. Mechanisms of inbreeding avoidance such as mate choice and sex-biased dispersal have also been documented across a variety of taxa. However, studies of inbreeding avoidance via mate choice are surprisingly scarce, and those that explicitly compare maternal and paternal kin are entirely absent in mammals. Here, we provide the first study to assess how behavioral inbreeding avoidance varies across kin classes in a population of wild baboons. We first examine the series of isolating barriers that prevent inbreeding, including death, dispersal, and mate choice, and we next use pedigree data to assess how behavioral inbreeding avoidance varies across kin classes. We found that while the demographic barriers of death and male-biased dispersal are extremely effective in limiting inbreeding in this population, we still found strong evidence for inbreeding avoidance via mate choice. In particular, while most kin classes exhibited inbreeding avoidance, maternal kin (mother-son pairs, maternal siblings) were more avoidant than paternal kin (father-daughter pairs, paternal siblings) despite having identical coefficients of relatedness. Finally, by taking advantage of a natural experiment in our study population, we also found that social groups with reduced sex-biased dispersal and reduced inbreeding avoidance via mate choice produced ten times as many inbred offspring.