Island populations are particularly vulnerable to genetic risk. The glossy black-cockatoo Calyptorhynchus lathami halmaturinus has been restricted to Kangaroo Island, South Australia, since the mid-20th century and had declined to a few hundred individuals before management-led recovery. To understand how this population bottleneck might have affected population structure, genetic diversity and inbreeding, we analyzed single nucleotide polymorphisms (SNPs), principally generated from feather samples collected from nestlings during two breeding seasons. We investigated differences in genetic variability between population ‘flocks’ across the island. Overall FIS was 0.02 and mean allelic richness was 1.84. Low pairwise FST values (-0.001-0.04) indicated genetic connectivity between the flocks, however, genetic differentiation (P ≤ 0.004) between all but the two eastern flocks suggests some limitations to gene flow. Seventeen per cent of individuals were highly inbred, with more than a third of these individuals from the most eastern flock. While there was no substantial population structure, analysis indicated some differentiation of the currently expanding eastern flock. Spatial autocorrelation found stronger than random relatedness amongst nestlings in nesting clusters, confirming suggestions from previous studies. The estimated effective population size (Ne) was 122, above the minimum (Ne ≥ 50 ) commonly thought needed to avoid inbreeding depression in the short term, with Ne values for two flocks also above this level. Our study highlights the importance of focussing on population genetics as well as numerical recovery when developing actions to manage threatened populations.
Wolf ( Canis lupus )—dog ( Canis familiaris ) hybrids are a widely recognized example of anthropogenic hybridization of conservation concern. In the Iberian Peninsula, wolves and dogs coexist in highly humanized landscapes, with many opportunities for interbreeding. Previous studies have documented wolf-dog hybridization here; however, their ability to estimate the frequency of this phenomenon was limited because of opportunistic, or geographically restricted sampling. Further, the use of non-standardized genetic markers limited comparability across studies. Here, we conducted a systematic non-invasive survey, collecting over 800 fecal samples across the species range in Iberia. Genetic analyses combined a mitochondrial DNA barcode for species identification, 13 autosomal microsatellites for individual identification, two sex markers, and a panel of 96 ancestry-informative SNP markers specifically developed for wolf-dog hybrid detection across Europe, which enables the assignment of hybrid classes up to second-generation backcrosses. Our results revealed a very low prevalence (< 2%) of wolf-dog hybrids in this population. Among 204 individually identified wolves, we detected three first-generation (F1) and one later-generation (F2/BCw) hybrids. Two of the identified hybrids were related, thus representing only three hybridization events, all located at the edge of the species distribution or in human disturbed areas. Simulations regarding the expected change in the genetic composition of the population with this prevalence of hybrids, and the observed underrepresentation of backcrosses, suggest reduced reproductive success in hybrids. The results imply that the risk of genetic swamping of wild wolves by domestic dogs is currently low in Iberia.
European gray wolf (Canis lupus) populations experienced severe range fragmentation due to human persecution, habitat loss, and prey depletion. In Portugal, the Iberian wolf (C. l. signatus) subpopulation south of Douro River faces a high extinction risk driven by long-term demographic decline and limited gene flow. This study aimed to identify the main factors limiting functional connectivity within this endangered subpopulation. We tested two hypotheses: isolation by distance (IBD), where genetic differentiation is primarily driven by geographic distance; and isolation by resistance (IBR), which posits that genetic differentiation is influenced by landscape and ecological factors that impede movement. Resistance surfaces were derived from habitat suitability models incorporating trade-offs between ecological resources and human disturbance. To ensure robust inference, we assessed wolf-dog admixture using Bayesian clustering and assignment to parental and hybrid classes. We identified 30 of the 39 wolves estimated to occur in the region, and conducted an individual-based landscape genetics analysis, relating pairwise genetic distances to geographic and resistance distances (i.e., least-cost distances) using multiple regression. Both hypotheses significantly explained genetic distances between individuals. However, after accounting for population structuring, their contributions decreased substantially, likely reflecting the influence of social structure and kinship. We suggest much of the remaining variance is largely shaped by high human-induced mortality, which limits long-distance dispersal. Improving connectivity in this wolf subpopulation requires addressing social and demographic barriers alongside landscape-level constraints. Mitigating human-wolf conflict and reducing mortality rates is essential for enhancing functional connectivity and ensuring the long-term viability of this endangered subpopulation.
Genetic monitoring is central to the conservation of threatened species, particularly those with small and isolated populations, as reduced diversity can limit long-term survival and adaptive potential. Islands are ideal for examining these processes due to restricted gene flow and the enhanced effects of genetic drift and inbreeding. The Egyptian vulture (Neophron percnopterus), a long-lived species in global decline, serves as a model for examining how insularity shapes genetic diversity and structure. The main goals of this study are: (i) to assess patterns of genetic diversity, inbreeding and differentiation in four island populations (Cabo Verde, Canary Islands, Balearic Islands, and Socotra) and compare them with their continental counterparts (Maghreb, Iberian Peninsula and Oman), and (ii) to evaluate temporal genetic changes using museum and contemporary samples from the formerly abundant population of Cabo Verde. Island populations generally exhibited reduced genetic diversity. In particular, Cabo Verde showed a pronounced decline in genetic diversity and increased inbreeding over only a few decades, a striking pattern given the species’ long generation time. The four island populations formed distinct genetic clusters, whereas mainland populations showed higher levels of admixture. Contemporary patterns reflect both long-term isolation and rapid recent genetic erosion associated with population decline, particularly in Cabo Verde. These findings highlight that insularity can increase genetic vulnerability. Although Egyptian vulture island populations are genetically unique, they are vulnerable and require targeted conservation to prevent introgression and preserve evolutionary distinctiveness, particularly in programs involving translocations or exchanges with continental populations.
The information on genetic diversity, population differentiation and admixture of invasive blackchin tilapia (Sarotherodon melanotheron) is important for understanding its introduction type and invaded mechanism in Thailand. Accordingly, S. melanotheron was collected from various geographic locations and genotyped with ten microsatellites (N = 268). Species identification by COI (N = 26) revealed that subspecies of invasive fish is S. melanotheron melanotheron. High genetic diversity of invasive S. melanotheron was found. The mean number of alleles (A) across each population was 4.100 – 8.100 with an allelic richness (AR), observed (Ho) and expected heterozygosity (He) of 3.3903 – 6.0453, 0.4450 – 0.6400 and 0.5495 – 0.6803, respectively. Allele distribution of UNH216, UNH159 and UNH169 in Samut Songkhram (the first appearance province of S. melanotheron) was different from neighboring provincial and water body-connected populations. Genetic distance between population was 0.060 – 0.344. Strong population differentiation was found based on PCoA, pairwise FST and AMOVA analyses suggesting that S. melanotheron was multiple introduced to Thailand. Population admixture analysis indicated that fish from Samut Songkhram did not display major passive migration to invade other areas, but the spreading route seemed to be from Phetchaburi (southern Thailand) to canal and provincial (Samut Sakhon Bangkok and Samut Prakan) populations in central Thailand. The gene pools of canal populations should be additionally affected by human-mediated activities (e.g. ornamental fish trade). The information supports multiple introductions of S. melanotheron from several native sources to various locations in Thailand.
