No abstract

The globally distributed sperm whale (Physeter macrocephalus) has a partly matrilineal social structure with predominant male dispersal. At the beginning of 2016, a total of 30 male sperm whales stranded in five different countries bordering the southern North Sea. It has been postulated that these individuals were on a migration route from the north to warmer temperate and tropical waters where females live in social groups. By including samples from four countries (n = 27), this event provided a unique chance to genetically investigate the maternal relatedness and the putative origin of these temporally and spatially co-occuring male sperm whales. To utilize existing genetic resources, we sequenced 422 bp of the mitochondrial control region, a molecular marker for which sperm whale data are readily available from the entire distribution range. Based on four single nucleotide polymorphisms (SNPs) within the mitochondrial control region, five matrilines could be distinguished within the stranded specimens, four of which matched published haplotypes previously described in the Atlantic. Among these male sperm whales, multiple matrilineal lineages co-occur. We analyzed the population differentiation and could show that the genetic diversity of these male sperm whales is comparable to the genetic diversity in sperm whales from the entire Atlantic Ocean. We confirm that within this stranding event, males do not comprise maternally related individuals and apparently include assemblages of individuals from different geographic regions.

Objective The Caribbean is an important global biodiversity hotspot. Adaptive radiations there lead to many speciation events within a limited period and hence are particularly prominent biodiversity generators. A prime example are freshwater fish of the genus Limia, endemic to the Greater Antilles. Within Hispaniola, nine species have been described from a single isolated site, Lake Miragoâne, pointing towards extraordinary sympatric speciation. This study examines the evolutionary history of the Limia species in Lake Miragoâne, relative to their congeners throughout the Caribbean. Results For 12 Limia species, we obtained almost complete sequences of the mitochondrial cytochrome b gene, a well-established marker for lower-level taxonomic relationships. We included sequences of six further Limia species from GenBank (total N  = 18 species). Our phylogenies are in concordance with other published phylogenies of Limia. There is strong support that the species found in Lake Miragoâne in Haiti are monophyletic, confirming a recent local radiation. Within Lake Miragoâne, speciation is likely extremely recent, leading to incomplete lineage sorting in the mtDNA. Future studies using multiple unlinked genetic markers are needed to disentangle the relationships within the Lake Miragoâne clade.

The Caribbean is one of the most important biodiversity hotspots on the planet due to the high level of species diversity and endemism in plants and animals. As elsewhere, adaptive radiations in the Caribbean lead to many speciation events within a limited period and hence are particularly prominent biodiversity generators. The general prediction from Island Biogeography that relates species richness to island size is valid for livebearing fishes in general in the Greater Antilles, where larger islands have higher numbers of species mainly due to in situ speciation. A prime example of this speciation process can be seen in the genus Limia, endemic to the Greater Antilles. Within Hispaniola, nine species have been described from a single isolated site, Lake Miragoâne, pointing towards extraordinary sympatric speciation in Limia. Few studies have examined the evolutionary history of the fishes found in Lake Miragoâne. Here, we address the gaps in present knowledge by providing a preliminary phylogeny of Limia and testing whether the species found in Lake Miragoâne may originated from an in situ radiation. We targeted the mitochondrial cytochrome b gene, a well-established marker for lower-level taxonomic relationships for which we obtained almost complete sequences for 13 species. The general topology of the phylogenies we produced are in concordance with other published phylogenies of Limia. There is also strong support that the species found in Lake Miragoâne in Haiti are indeed monophyletic (BS=97; PP=1.0), confirming the hypothesis of a recent local radiation. Within Lake Miragoâne, speciation is likely extremely recent, leading to incomplete lineage sorting in the mtDNA. Future studies are needed using multiple unlinked genetic markers to disentangle the relationships within the Lake Miragoâne clade.