Large carnivores have been subjected to overexploitation and extensive habitat loss for centuries. Reintroduction has become an increasingly used tool for recovering and reestablishing large carnivore populations; however, most reintroductions have either failed or resulted in small populations that are vulnerable to deleterious demographic, environmental, and genetic effects that can lead to population loss or extinction. Longterm monitoring of small, reintroduced populations is critical to population persistence and viability. To evaluate long-term reintroduction success and current status of a recently reintroduced, small black bear (Ursus americanus) population in the Big South Fork area of Kentucky, I used non-invasive hair sampling in a systematic, closedpopulation capture-mark-recapture study design. I used ≥ 20 microsatellite loci to identify individual bear, quantify genetic diversity, investigate genetic relatedness, estimate population abundance and density, and investigate patterns of range expansion. The Big South Fork population is comprised of closely-related individuals, is small (N = 40; 95% CI: 30-113), of low density (0.03 bear/km2), has experienced minimal range expansion, and exhibits decreased genetic diversity (HE = 0.698). Because of prolonged isolation from nearby subpopulations, the Big South Fork population remains vulnerable and requires immediate and continued monitoring.

Density-dependence is considered one of the most important regulators of population growth, and it has been documented across a wide variety of species. Typically, population growth rate and components thereof decline with increasing density (i.e., negative density-dependence); however, in species that exhibit high population densities and social behavior, positive density-dependence (i.e., Allee effect) may occur at low density. June sucker, a federally endangered lake sucker endemic to Utah Lake, Utah, USA, occurred historically at high density, and it exhibits coordinated feeding behavior. These characteristics indicate a potential for the existence of an Allee effect at current low population densities. To determine effects of density on growth, survival, and diet, I experimentally manipulated density of young June sucker in replicated enclosures in a natural environment. Larval June sucker were placed in enclosures at four different densities, and growth, survival, and diet of fish, and availability of prey (to determine selectivity) were measured at two time intervals. Both individual growth and survival were significantly lower at the lowest density compared to higher densities, indicative of a component Allee effect. Diets of individuals at low densities were more selective than diets of individuals at intermediate and high densities, suggesting a change in feeding strategy with density. Reduced growth and survival at low density suggests that corresponding, highly selective, feeding strategies may be less efficient than feeding strategies employed at higher densities. Allee effects appear to be an important consideration for recovery of this endangered species, and such effects may be common in historically abundant, but currently rare species.

Population structure, biogeography and phylogenetic relationships of the fruit bat genus Rousettus have been studied in Africa and adjacent regions. The current population patterns of rousettine fruit bats in the Old World are influenced by several environmental attributes, namely the topography, climate and land cover. These variables are mirrored in fruit bat plesiomorphies related to the ecological niche of tropical flying frugivore, as well as apomorphies of rousettines including echolocation ability, roosting in caves and dispersal capacity in open landscapes with discontinuous tree cover. Phylogenetic relationships among species and subspecies of the genus have been indicated and confronted with the existing colonization scenarios. Insular populations (including habitat islands within desert oases) show frequent genetic differentiation from their mainland relatives suggesting successful founder events after traversing stretches of unsuitable habitats. Genetic differentiation evolving in less distant islands suggests involving behavioural mechanisms maintaining cohesion of isolated demes as site fidelity and natal habitat-biased dispersal. In sub-Saharan mainland Africa within the large range reaching from the southern border of Sahara to Cape Peninsula, Rousettus populations share a...

Population structure, biogeography and phylogenetic relationships of the fruit bat genus Rousettus have been studied in Africa and adjacent regions. The current population patterns of rousettine fruit bats in the Old World are influenced by several environmental attributes, namely the topography, climate and land cover. These variables are mirrored in fruit bat plesiomorphies related to the ecological niche of tropical flying frugivore, as well as apomorphies of rousettines including echolocation ability, roosting in caves and dispersal capacity in open landscapes with discontinuous tree cover. Phylogenetic relationships among species and subspecies of the genus have been indicated and confronted with the existing colonization scenarios. Insular populations (including habitat islands within desert oases) show frequent genetic differentiation from their mainland relatives suggesting successful founder events after traversing stretches of unsuitable habitats. Genetic differentiation evolving in less distant islands suggests involving behavioural mechanisms maintaining cohesion of isolated demes as site fidelity and natal habitat-biased dispersal. In sub-Saharan mainland Africa within the large range reaching from the southern border of Sahara to Cape Peninsula, Rousettus populations share a...

L’interaction de processus génétiques et démographiques peut générer des vortex d’extinction. Chez les Hyménoptères, les mâles sont haploïdes et les femelles diploïdes. Chez les espèces avec sl-CSD (single-locus complementary sex determination), les haploïdes, se développent en mâles et les diploïdes hétérozygotes au gène du CSD, en femelles. Les diploïdes homozygotes sont des mâles non viables ou stériles. Des études théoriques suggèrent que la production de mâles diploïdes peut entraîner les petites populations d’Hyménoptères dans un vortex d’extinction. Le premier objectif est d’encourager le dialogue entre génétique et démographie en proposant une définition des effets Allee élémentaires générés par des processus génétiques, dont nous avons identifié des exemples dans la littérature. Le deuxième objectif est de rechercher l’existence d’un effet Allee génétique dans des populations de Venturia canescens, un Hyménoptère parasitoïde avec sl-CSD. Des marqueurs microsatellites ont été élaborés et utilisés pour montrer une relation négative entre diversité génétique et proportion de mâles diploïdes dans des populations isolées ou goulotées. Les mâles diploïdes s’accouplent mais sont stériles. La dépression de consanguinité affectant les femelles est faible. Nous avons créé et suivi des populations expérimentales de V. canescens avec différents niveaux de diversité génétique. Un effet Allee génétique dû à la production de mâles diploïdes a été détecté mais il n’influençait ni le taux d’accroissement ni la probabilité d’extinction des populations. Les extinctions observées semblent surtout due à la stochasticité démographique. / Genetic and demographic processes can drive small populations to extinction. Their interaction can generate extinction vortices. In Hymenoptera, males are haploid and females are diploid. In species with single-locus complementary sex determination (sl-CSD), hemizygous at the CSD gene develop in males and heterozygous diploids, in females. Homozygous develop in diploids males, often unviable or sterile. Theoretical studies suggest that the production of diploid males associated with demographic and environmental stochasticity may drive small populations into an extinction vortex.The first objective is to stimulate collaboration between genetics and demography by proposing a definition for component Allee effects generated by genetic processes. Component and demographic genetic Allee effects were detected in the literature.The second objective was to investigate the presence of a genetic, and maybe demographic, Allee effect in populations of the parasitoid Venturia canescens, a Hymenoptera with sl-CSD. Microsatellite markers were developed and used to show a negative relationship between genetic diversity and proportion of diploid males in isolated and bottlenecked populations. Diploid males can mate but they are sterile. Inbreeding depression affecting females is negligible. We created and monitored experimental populations of V. canescens with different levels of genetic diversity. A genetic Allee effect due to the production of diploid males was detected but it did not influence the growth rate or the probability of extinction of populations. Extinction events observed thus seem mainly due to demographic stochasticity.