From population structure to individual behaviour: genetic analysis of social structure in the European wild rabbit (Oryctolagus cuniculus)

The European wild rabbit (Oryctolagus cuniculus) lives in stable, territorial breeding groups, with male-biased natal dispersal, female philopatry, and a polygynous mating system. It was introduced into Britain in the 11 th century and kept in captive warrens as a food and fur resource. Populations expanded in the wild in the 18th century. Microsatellite markers were employed to examine the genetic structure of wild rabbit populations on three spatial scales: macrogeographic structure of 17 populations in East Anglia, microgeographic structure of a tagged population in the grounds of the University of East Anglia over four consecutive years, and pairwise kinships and individual movement within this tagged population. Populations across East Anglia were found to be genetically distinct, and heterozygote deficits were observed at all loci indicating sub-division within sampled populations. Analysis of the tagged population confirmed that rabbit populations are genetically sub-divided among social groups. Studying this population over four consecutive years revealed that as the population size increased, the number of social groups increased. Analysis of individual pairwise relatedness of females indicated that individuals did not necessarily group with kin, and behavioural data indicate that an optimum group size may exist which maximizes reproductive success.     

Molecular genetic diversity in populations of the stingless bee Plebeia remota: A case study

Genetic diversity is a major component of the biological diversity of an ecosystem. The survival of a population may be seriously threatened if its genetic diversity values are low. In this work, we measured the genetic diversity of the stingless bee Plebeia remota based on molecular data obtained by analyzing 15 microsatellite loci and sequencing two mitochondrial genes. Population structure and genetic diversity differed depending on the molecular marker analyzed: microsatellites showed low population structure and moderate to high genetic diversity, while mitochondrial DNA (mtDNA) showed high population structure and low diversity in three populations. Queen philopatry and male dispersal behavior are discussed as the main reasons for these findings.     

Fine-scale genetic structuring in a natural population of European wild rabbits (Oryctolagus cuniculus)

The genetic structure of a free-living tagged population of European wild rabbits (Oryctolagus cuniculus) was investigated for two consecutive years (1990 and 1991) using 10 polymorphic microsatellite loci. A specific social behaviour, the formation of stable breeding groups, influenced the genetic structure of the population. These breeding groups were shown to constitute genetically differentiated units with low levels of gene flow between them. The average relatedness among members of a social group was higher than within the population as a whole. As a result of female philopatry coupled with male-biased natal dispersal, the relatedness of females was higher than that of males, both within social groups and in the whole population. Furthermore, the average relatedness of females within groups was twice the relatedness of females between groups. This study reveals marked fine-scale, intrapopulation genetic structure, which is attributable to the social behaviour of the European wild rabbit.     

Population genetic structure of the common warthog (Phacochoerus africanus) in Uganda: evidence for a strong philopatry among warthogs and social structure breakdown in a disturbed population

Fine‐scale genetic structure of large mammals is rarely analysed. Yet it is potentially important in estimating gene flow between the now fragmented wildlife habitats and in predicting re‐colonization following local extinction events. In this study, we examined the extent to which warthog populations from five localities in Uganda are genetically structured using both mitochondrial control region sequence and microsatellite allele length variation. Four of the localities (Queen Elizabeth, Murchison Falls, Lake Mburo and Kidepo Valley) are national parks with relatively good wildlife protection practices and the other (Luwero), not a protected area, is characterized by a great deal of hunting. In the total sample, significant genetic differentiation was observed at both the mtDNA locus (F_ST = 0.68; P < 0.001) and the microsatellite loci (F_ST = 0.14; P < 0.001). Despite the relatively short geographical distances between populations, significant genetic differentiation was observed in all pair‐wise population comparisons at the two marker sets (mtDNA F_ST = 0.21–0.79, P < 0.001; microsatellite F_ST = 0.074–0.191, P < 0.001). Significant heterozygote deficiency was observed at most loci within protected areas while no significant deviation from Hardy–Weinberg expectation was observed in the unprotected Luwero population. We explain these results in terms of: (i) a strong philopatry among warthogs, (ii) a Wahlund effect resulting from the sampling regime and (iii) break down of social structure in the disturbed Luwero population.     

Patterns of population subdivision and gene flow in the ant Nothomyrmecia macrops reflected in microsatellite and mitochondrial DNA markers

The Australian endemic ant Nothomyrmecia macrops is renowned for having retained a large proportion of 'primitive' morphological and behavioural characters. Another less studied peculiarity of this species is the production of short-winged (brachypterous) female sexuals, which presumably are poor dispersers. The males, in contrast, bear a full set of normally developed wings and thus may disperse widely. We investigated patterns of genetic differentiation within and among three distantly separated populations in South Australia using nine polymorphic microsatellite loci and four regions of mitochondrial DNA (COI, COII, Cytb, lrRNA). We sampled eight subpopulations, one in the Lake Gilles CP, two near Penong and five around Poochera where distances ranged from 360 km to sites separated by 2-10 km. Only little differentiation was found at the local scale (within the assumed dispersal distance of males) using nuclear markers, whereas the three distant locations were moderately differentiated (FST = 0.06). Mitochondrial DNA genetic structure was much more pronounced on all scales (phiST = 0.98), with regular differences in both haplotype composition and frequency even occurring among closely located sites. This lack of congruence between nuclear and mitochondrial markers strongly suggests limited female dispersal and male-biased gene flow among populations. As to the conservation status of the species there is no evidence for severe population reductions in the recent past, which would have left populations genetically depauperate.     

Microgeographic genetic structure and intraspecific parasitism in the ant Leptothorax nylanderi

1. Genetic colony structure of the small central European ant Leptothorax nylanderi is affected strongly by ecological constraints such as nest site availability and intraspecific social parasitism. 2. Although L. nylanderi is generally monogynous and monandrous, more than a quarter of all nests collected in a dense population near Würzburg, Germany, contained several matrilines. As shown by microsatellite analysis, the average nest‐mate relatedness in these nests was 0.20. Genetically heterogeneous nests arise from nest take‐over by alien colonies or founding queens, a result of severe competition for nest sites. 3. In summer, more than one‐third of all colonies inhabited several nest sites at a time. Polydomy appears to be rather limited, with two or three nests belonging to a single polydomous colony. 4. Queens appear to dominate male production; only a small fraction (8%) of males was definitively not progeny of the queen present but might have been worker progeny or offspring of another queen. 5. Strong evidence for heterozygote deficiency was found and a total of nine diploid males was discovered in two colonies. These findings suggest deviation from random mating through small, localised nuptial flights.     

Paternity assessment and population subdivision in a natural population of the larger mouse-eared bat Myotis myotis

A hypervariable simple sequence locus and mitochondrial D-loop sequences were used to analyse genetically a natural population of the larger mouse-eared bat Myotis myotis in southern Bavaria. Tests for population subdivision and direct observations suggest that females return to their natal sites, while males disperse. The males present in female nursery colonies are not related to the females. Paternity assessment for 46 offspring from a particular nursery colony showed that there are no males that monopolize the reproduction, and that the resident males in the colony had only a small mating success. Instead, the results suggest that females actively seek matings outside their colony. Most interestingly, it appears that a group of males about 16 km away from the nursery colony had a relatively high mating success and that this group of males may be related to the females of the nursery colonies. If this finding can be confirmed in a larger study, it may have important consequences for future conservation strategies.     

Humans as primates: The social relationships of Efe pygmy men in comparative perspective

The Efe are short-statured specialized hunger-gatherers living in the moist tropical forest in northeast Zaire. They live in small mobile groups averaging 18 individuals and practice viripatrilocal residence — what primatologists refer to as male philopatry and female dispersal. This study uses methods commonly employed by primatologists to study the social relationships of Efe men. It compares their association and affiliation patterns with those of two nonhuman primate species that show male philopatry and female transfer. The analyses of 376 hr of focal behavior observations on 16 Efe men reveal that the majority of their associations were with other adult men. Men associated preferentially with kin over non-kin, and with close kin more than with distant kin. Men's close relationships, or companionships,sensu Smuts' (1985) friendships among anubis baboons, were predominantly with other adult men; however, each man who cohabited with a woman had his strongestcompanionship by far with that woman. These quantitative measures of affinity are consistent with the Efe's pattern of viripatrilocal residence, where-by males remain in their natal group with their close male kin and females join or are recruited from other patriclans. The social relationships of Efe men are similar in some respects to those of hamadryas and chimpanzees; however, Efe men's social networks are larger and more fluid. We speculate that the explanation proposed for male philopatry and female dispersal among nonhuman primates also applies to the Efe.     

Microsatellite loci reveal highly significant genetic differentiation among Atlantic salmon (Salmo salar L.) stocks from the east coast of Canada

Allele frequency data from eight microsatellite loci provide evidence of highly significant genetic differentiation among stocks of Atlantic salmon Salmo salar L. from the Bay of Fundy, eastern and north-western Nova Scotia and Newfoundland. Estimates of genetic structure ( R _ST and θ) were significant both among all samples taken from the different geographical locations and among samples from geographical regions for which more than one stock was sampled. Samples from the Bay of Fundy taken from stocks which are phenotypically and behaviourally diverse showed particularly high levels of genetic structure. Rogers', allele sharing and (δμ)² distances also revealed significant differences among stock samples and were significantly correlated [Rogers' and (δμ)²] with sea distance between rivers. Results suggest that stocks of Atlantic salmon in eastern Canada are highly diverse genetically and that this should be an important consideration in any management programme for stocks in the area.