An assessment of the genetic diversity and structure within and among populations of wild pigs (Sus scrofa) from Australia and Papua New Guinea

In many regions in the world the reduction in population sizes of native pigs is a conservation concern (Li et al. 2000; Martinez et al. 2001). However, in Australia, feral (or wild) pigs are a significant invasive species, and there are upwards of 10 million feral pigs present, inhabiting over 40% of the continent (Choquenot et al. 1996). Coupled with these large numbers and advances made in marker technology, there is an increasing awareness of the value in quantifying (and understanding) the biodiversity retained in non-commercial livestock breeds (e.g. Hall and Bradley, 1995). Well-characterized microsatellite markers, such as those recommended by the Food and Agriculture Organization and International Society for Animal Genetics (FAO-ISAG), are ideal for such studies. There is an increasing amount of data being generated from indigenous pigs, including Asian (Li et al. 2000; Kaul et al. 2001), American (Lemus-Flores et al. 2001) and wild European (Laval et al. 2000; Martinez et al. 2000; Vernesi et al. 2003) breeds. However, there is no such information available on the diversity of wild pigs in Australia or Papua New Guinea. Overall, the preliminary findings suggest that Australian feral pigs are genetically diverse, with heterozygosity and allelic diversity at 0.758 and 11.0 alleles per locus on average, respectively

Measuring the Demographic and Genetic Effects of Pest Control in a Highly Persecuted Feral Pig Population

Substantial efforts have been made to identify the most effective practices for the control and management of invasive vertebrate pest species, such as the feral pig (Sus scrofa). We investigated the demographics, abundance, and molecular ecology of a persecuted feral pig population that was subjected to control. We then applied methodologies to determine if we could retrospectively quantify any changes in the population structure or dynamics of these pigs. Feral pig demographic and abundance parameters indicated that in this population of feral pigs, there were very few detectable changes between the two aerial culling years. We observed this despite environmental conditions being optimal for control. Genetic results indicated that pigs culled in the latter 2004 cull were genetically identical to those pigs that inhabited the area a year earlier. The genetic population was geographically larger than the sample area. These findings indicate that the recovery in feral pig density witnessed in the controlled area was not a result of reinvasion from a separate, genetically distinct population, but rather, it was the result of reinvasion from feral pigs outside the study area but within the same genetic population. Importantly, we were unable to detect any recent genetic bottlenecks. This approach has considerable potential for auditing the effectiveness of control programs of pest species and assessing the feasibility of impacting upon or locally eradicating many other free-ranging pest species

The sociogenetic structure of a controlled feral pig population

In Australia, the feral pig (Sus scrofa) is a significant vertebrate pest that has an impact on agricultural production, public health and ecosystem integrity. Although feral pigs are controlled throughout much of their range, little is known about the impact that these control programs have had on the social biology, structure and the dispersal of pigs. To begin to address this, we collected demographic data and genetic samples from 123 feral pigs culled during a regional aerial shooting program over 33 pastoral properties in the semi-arid rangelands of southern Queensland, Australia. Sampling was carried out after two years of extensive control efforts (aerial 1080-baiting) and the samples therefore represented a controlled, persecuted population with a bias towards young animals. The analysis of 13 microsatellite loci suggested that females will accept multiple matings, females form loose mobs that appear to be highly dynamic social groups, and males will travel large distances between mobs. These data indicate that feral pigs in this population had a high level of social contact and form a single open population with no evidence of genetic (population) structuring. Such information may be important to integrate into management strategies, particularly the development of contingency plans regarding the spread of wildlife disease

Comparison of methods to detect rare and cryptic species: A case study using the red fox (Vulpes vulpes)

Choosing the appropriate method to detect and monitor wildlife species is difficult if the species is rare or cryptic in appearance or behaviour. We evaluated the effectiveness of the following four methods for detecting red foxes (Vulpes vulpes) on the basis of equivalent person hours in a rural landscape in temperate Australia: camera traps, hair traps (using morphology and DNA from hair follicles), scats from bait stations (using DNA derived from the scats) and spotlighting. We also evaluated whether individual foxes could be identified using remote collection of their tissues. Genetic analysis of hair samples was the least efficient method of detection among the methods employed because of the paucity of samples obtained and the lack of follicles on sampled hairs. Scat detection was somewhat more efficient. Scats were deposited at 17% of bait stations and 80% of scats were amplified with a fox-specific marker, although only 31% of confirmed fox scats could be fully genotyped at all six microsatellite loci. Camera trapping and spotlighting were the most efficient methods of detecting fox presence in the landscape. Spotlighting success varied seasonally, with fox detections peaking in autumn (80% of spotlighting transects) and being lowest in winter (29% of transects). Cameras detected foxes at 51% of stations; however, there was limited seasonality in detection, and success rates varied with camera design. Log-linear models confirmed these trends. Our results showed that the appropriate technique for detecting foxes varies depending on the time of the year. It is suggested that wildlife managers should consider both seasonal effects and species biology when attempting to detect rare or elusive species