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.
Coral populations on inshore reefs of the Great Barrier Reef (GBR) face increasing pressures from environmental stressors. Genetic diversity and connectivity are key determinants of coral adaptive capacity. Acropora kenti forms at least four genetically distinct clusters distributed across hundreds of kilometres along the GBR. One cluster which is potentially vulnerable due to restricted geographic distribution is found at Yunbenun (Magnetic Island). Here, we conducted a genetic assessment of A. kenti populations from seven reefs around Yunbenun and eight adjacent inshore and mid-shelf reefs in the central GBR to identify their population structure, genetic diversity and connectivity. Using single nucleotide polymorphisms (SNPs) we demonstrate that a genetically distinct (Fst >0.33) lineage dominates at all bays around Yunbenun but is rarely found on adjacent reefs. Fine-scale analysis within the Yunbenun lineage revealed a pattern of isolation by distance, driven by limited gene flow. Admixture analysis supported by hydrodynamic modelling shows that larval dispersal is occurring between Yunbenun and surrounding reefs, but gene flow remains limited. Populations at Yunbenun have lower allelic richness (p < 0.001) and much lower effective population sizes (Ne = 1348 (northern bays), Ne = 91 (southern bays)) compared with adjacent reefs (Ne = 9494). These findings demonstrate that although the genetic diversity of A. kenti across the GBR remains high, isolated and potentially locally adapted populations such as those at Yunbenun may be at risk of genetic decline, undermining their adaptive potential and increasing their conservation concern.
Understanding the drivers of diversification in global biodiversity hotspots is critical for conservation and for advancing evolutionary theory. The historically understudied Central California bioregion offers important insight regarding biodiversity hotspot dynamics. We examined the diversification and population structure of the Bernardino Blue butterfly (Euphilotes bernardino) species group across its entire range in coastal California from Monterey County to the Mexican border using single-nucleotide polymorphisms from ddRAD. Earlier work demonstrated surprisingly high diversity in this butterfly group in Southern California, and we reveal equally high levels in Central California. The areas of greatest genetic diversity were not correlated with apparent changes in geography or habitat. We found that an area of Central California encompassing Vandenberg Space Force Base contains a population of E. bernardino that is more diverged than any other across hundreds of kilometers of similar habitat. The agents of diversification are unclear and may pertain to ancient geological events, like the formation and filling of seaways, that are long gone. A refined assessment of patterns across taxa will improve our ability to predict and conserve biological diversity hotspots while furthering our understanding of global diversification patterns.
Linaria flava subsp. sardoa is a critically endangered plant endemic to the coastal sand dunes of Sardinia (Italy) and Corsica (France), and is recognized under European frameworks for biodiversity conservation and strict protection actions. However, despite its conservation status, little is known about its genomic landscape. Investigating its population genetic structure is essential to assess levels of genetic diversity, and detect potential inbreeding or isolation among populations. Such information provides a critical basis for the development of effective management and conservation strategies. In this study a genotyping-by-sequencing approach was used to identify 24,312 Single Nucleotide Polymorphisms and to investigate genomic diversity and population structure in 96 samples of L. sardoa, belonging to eight populations. Our results evidenced high levels of inbreeding (mean inbreeding coefficient = 0.87), low levels of genetic diversity within population (mean He = 0.05), coupled with high genetic differentiation between populations of L. sardoa (mean pairwise FST=0.57). These patterns suggest a lack of genetic diversity, long-term isolation and limited gene flow, raising concerns about the species’ resilience to environmental change and stochastic events, and calling for immediate conservation actions. Only some individuals from the MOL population showed significantly lower levels of inbreeding and higher levels of heterozygosity. All these findings provide valuable insights to inform both current and future conservation strategies for the species. A possible conservation action for L. sardoa could therefore be the reinforcement of existing populations including in the donor pool at least a small proportion of individuals from other populations, in particular from populations, like MOL, showing higher genetic diversity.
