New microsatellite loci for the endangered scalloped hammerhead shark, Sphyrna lewini

We isolated 15 microsatellite markers for the scalloped hammerhead shark, Sphyrna lewini. Loci were tested on 80 specimens of S. lewini from four Eastern Pacific samples. The number of alleles per locus ranged from 6 to 31 (mean = 14). Observed and expected levels of heterozygosity per locus ranged from 0.39 to 0.91 (mean = 0.70) and from 0.54 to 0.90 (mean = 0.76), respectively. No pairs of loci were in gametic disequilibrium after Bonferroni correction of α. One locus showed significantly lower heterozygosity than expected under Hardy–Weinberg proportions in two populations, possibly caused by null alleles.     

From the Apennines to the Alps: colonization genetics of the naturally expanding Italian wolf (Canis lupus) population

Wolves in Italy strongly declined in the past and were confined south of the Alps since the turn of the last century, reduced in the 1970s to approximately 100 individuals surviving in two fragmented subpopulations in the central-southern Apennines. The Italian wolves are presently expanding in the Apennines, and started to recolonize the western Alps in Italy, France and Switzerland about 16 years ago. In this study, we used a population genetic approach to elucidate some aspects of the wolf recolonization process. DNA extracted from 3068 tissue and scat samples collected in the Apennines (the source populations) and in the Alps (the colony), were genotyped at 12 microsatellite loci aiming to assess (i) the strength of the bottleneck and founder effects during the onset of colonization; (ii) the rates of gene flow between source and colony; and (iii) the minimum number of colonizers that are needed to explain the genetic variability observed in the colony. We identified a total of 435 distinct wolf genotypes, which showed that wolves in the Alps: (i) have significantly lower genetic diversity (heterozygosity, allelic richness, number of private alleles) than wolves in the Apennines; (ii) are genetically distinct using pairwise F(ST) values, population assignment test and Bayesian clustering; (iii) are not in genetic equilibrium (significant bottleneck test). Spatial autocorrelations are significant among samples separated up to c. 230 km, roughly correspondent to the apparent gap in permanent wolf presence between the Alps and north Apennines. The estimated number of first-generation migrants indicates that migration has been unidirectional and male-biased, from the Apennines to the Alps, and that wolves in southern Italy did not contribute to the Alpine population. These results suggest that: (i) the Alps were colonized by a few long-range migrating wolves originating in the north Apennine subpopulation; (ii) during the colonization process there has been a moderate bottleneck; and (iii) gene flow between sources and colonies was moderate (corresponding to 1.25-2.50 wolves per generation), despite high potential for dispersal. Bottleneck simulations showed that a total of c. 8-16 effective founders are needed to explain the genetic diversity observed in the Alps. Levels of genetic diversity in the expanding Alpine wolf population, and the permanence of genetic structuring, will depend on the future rates of gene flow among distinct wolf subpopulation fragments.     

Wolves in the Great Lakes region: a phylogeographic puzzle

Empirical studies demonstrate that natural hybridization in animals is more common than thought so far ( Mallet 2005 ), particularly among species that originated recently through cycles of population contraction–expansion arising from climate changes over the last glacial period, the Pleistocene. In addition, the post‐glacial global growth of human populations has fostered anthropogenic hybridization events, mediated by habitat changes, the persecution of large predators and the introduction of alien species ( Allendorf et al. 2001 ). The Canis lineage shows cases of both natural and anthropogenic hybridization, exacerbating the controversy about the number of species that should be formally validated in the taxonomic lists, the evolutionary role of genetic introgression and the ways to manage hybrids with invading wild or domesticated populations. The study by Wheeldon et al. (2010) , published in this issue of Molecular Ecology, adds a new piece to the intricate puzzle of evolution and taxonomy of Canis in North America. They show that sympatric wolves (C. lupus) and coyotes (C. latrans) are not (extensively) hybridizing in the western North American Great Lakes region (GLR). Widespread hybridization between coyotes and a genetically distinct, but closely related, wolf‐like population (the eastern wolf) occurred in the northeastern regions of North America. In Wheeldon et al.’s (2010) opinion, these data should prove definitely that two different species of wolf (the western gray wolf C. lupus and the eastern wolf C. lycaon) and their hybrids are distributed across the GLR.     

Conflicts in maintaining biodiversity at multiple scales

Biodiversity consists of multiple scales, including functional diversity in ecological traits, species diversity and genetic diversity within species, and is declining across the globe, largely in response to human activities. While species extinctions are the most obvious aspect of this, there has also been a more insidious loss of genetic diversity within species. While a vast literature concerns each of these scales of biodiversity, less is known about how different scales affect one another. In particular, genetic and species diversity may influence each other in numerous ways, both positively and negatively. However, we know little about the mechanism behind these patterns. In this issue of Molecular Ecology, Nestmann et al. (2011) experimentally explore the effect of species and functional diversity and composition of grassland plant communities on the genetic structure of one of the component species. Increasing species richness led to greater changes in the genetic composition of the focal populations over 4 years, primarily because of genetic drift in smaller population sizes. However, there were also genetic changes in response to particular plant functional groups, indicating selective differences driven by plant community composition. These results suggest that different levels of biodiversity can trade-off in communities, which may prove a challenge for conservation biologists seeking to preserve all aspects of biodiversity.     

Artificial Occurrence of the Fallow Deer, Dama dama dama (L., 1758), on the Island of Rhodes (Greece): Insight from mtDNA Analysis

We investigated the origins of the fallow deer (Dama dama dama) of Rhodes by both morphological and molecular means. Our results show that these deer have homogeneous phenotypic patterns. All specimens fell within the common colour coat variety typical of the wild form. The Rhodian deer appear to be rather small, especially when compared with specimens from central and northern Europe. We then sequenced the HVR-I of 13 deer from Rhodes and compared these sequences with other 31 samples obtained from different European and Anatolian populations of fallow deer. Out of 44 sequences, 23 haploypes were found. When compared to the Turkish and Italian populations, the population of Rhodes revealed lower values of within population genetic diversity. The fallow deer from Rhodes are characterized by an 80-bp mitochondrial DNA (mtDNA) insertion not found elsewhere. As a consequence, all the deer from Rhodes form a tight cluster, distinct from all other fallow deer populations. This uniqueness makes the conservation and management of the Rhodian population particularly urgent.