Behavioural ecology, genetics and success of African wild dogs Lycaon pictus (Temminck, 1820) in KwaZulu-Natal, South Africa

Abstract

The African wild dog (Lycaon pictus) is one of Africa’s most endangered species, with fewer than 5,000 individuals surviving in the wild. Most of the remaining populations are increasingly fragmented and small, making loss of genetic diversity, reduced gene flow and inbreeding depression major concerns for the species. Recent efforts to conserve and increase severely declined numbers of wild dogs in South Africa have been focused on reintroductions to small protected areas to form a large metapopulation. The subpopulation in KwaZulu-Natal (KZN) was the first created and is currently the second largest population in the country with approximately 114 individuals. The overall goal for wild dog conservation in KZN is to establish a large, self-sustaining population within the province. This study evaluated the genetics and behaviour of the wild dogs in the province and explored how these factors influence long-term population health. An assessment of the progress made through reintroduction efforts to date was conducted by examining the current genetic diversity of the population and the pack and population dynamics shaping it. These findings were also used to investigate strategies for advancing the population to viable levels in the future. The scope of the project was divided into five topics to address the most crucial and intriguing aspects of African wild dog biology, conservation and management. First, non-invasive faecal genetic techniques were refined for field sampling of wild dogs in order to accurately genotype individuals and assess population heterozygosity. Second, the influences of inbreeding and genetic heterozygosity on fitness traits were investigated to determine if effects of inbreeding depression were apparent in the current population. Third, reproductive sharing among dominant and subordinate wild dogs was evaluated using genetic parentage analyses and long-term behavioural and demographic data. Fourth, the extent of inbreeding avoidance in wild dog reproduction was examined and the impact of this behaviour on future population persistence explored. Lastly, a population viability assessment using genetic inputs and goals was conducted for the current KZN wild dog population and strategies for the establishment of a viable future population were suggested. Genotyping and sampling errors were identified as significant sources of error in non-invasive analyses using faecal samples from wild dogs. Software assessments and replications were used to detect and correct genotyping errors. Sampling errors occurring in the field were corrected by evaluating multiple faecal samples from individual wild dogs, comparing matching individual blood and faecal genotypes, and using a large number of microsatellite loci to the identification of unique individuals in the dataset. Results showed that although genotyping and sampling errors were significant in our faecal DNA investigation of wild dogs, it is possible to correct these errors to generate consistent and accurate genotypes. Whenever possible, future genetic studies on African wild dogs and other endangered carnivores should apply these non-invasive techniques as they avoid handling of these stress-sensitive animals and have proven to be a reliable method of attaining good quality DNA. Though some cases of incest have been observed in the KZN wild dog population, the deleterious effects of inbreeding depression have only moderately begun to show on the lifespans of inbred individuals. Compared to non-inbred individuals, inbred wild dogs (f ≥ 0.25) had significantly shorter lifespans. However, this trend was limited to a small number of packs, indicating that although this seems to be evidence of inbreeding depression, a larger sample size is needed to confirm this. These results provide baseline data on the genetic diversity and fitness of the population and highlight the importance of tracking these characteristics in the future to ensure a healthy population. Within the parentage analyses, a substantial portion of reproductive sharing between dominants and subordinates was discovered in packs that contained siblings of the alpha pair. Alpha females mated annually, whereas subordinate betas bred in over half of all breeding years. Regardless of the number of adult males in the pack, litters of mixed paternity occurred in over 50% of years. Alpha males sired just over half of pups while one or two subordinate males sired the remaining pups in each pack. A skewed adult sex-ratio and frequent alpha mortalities for females and behavioural aggression in males allowed most individuals to attain dominant status in their lifetime. These findings suggest that more individuals than expected were able to contribute to reproduction in the population. In addition, reproductive partitioning in wild dogs is mediated through a combination of demographic, behavioural and hormonal factors. Extensive behavioural and genetic data confirm that wild dogs largely avoid mating with kin and suggest that avoidance is based on familiarity since only one inbreeding pair had prior association with each other. Computer-simulated populations revealed that preventing relatives from breeding could cause demographic declines and extinction due to an absence of unrelated mates. Although stronger inbreeding avoidance maintained significantly more genetic variation, small, isolated wild dog populations could encounter potentially severe demographic impacts of these behavioural mechanisms.