Abstract
The Cuban solenodon (Solenodon cubanus) is one of the most enigmatic mammals and is an extremely rare species with a distribution limited to a small part of the island of Cuba. Despite its rarity, in 2012 seven individuals of S. cubanus were captured and sampled successfully for DNA analysis, providing new insights into the evolutionary origin of this species and into the origins of the Caribbean fauna, which remain controversial. We conducted molecular phylogenetic analyses of five nuclear genes (Apob, Atp7a, Bdnf, Brca1 and Rag1; total, 4,602 bp) from 35 species of the mammalian order Eulipotyphla. Based on Bayesian relaxed molecular clock analyses, the family Solenodontidae diverged from other eulipotyphlan in the Paleocene, after the bolide impact on the Yucatan Peninsula, and S. cubanus diverged from the Hispaniolan solenodon (S. paradoxus) in the Early Pliocene. The strikingly recent divergence time estimates suggest that S. cubanus and its ancestral lineage originated via over-water dispersal rather than vicariance events, as had previously been hypothesised.
Highlights
The supermatrix phylogenetic analyses of five exon regions of nuclear DNA (nucDNA) genes demonstrated that Solenodontidae diverged first among the four families of Eulipotyphla (Solenodontidae, Erinaceidae, Soricidae and Talpidae[23]; Fig. 1 and Supplementary Fig. S1; bootstrap proportion = 70, posterior probability = 0.93), followed by Talpidae, with Erinaceidae and Soricidae forming a clade. This is congruent with one previous study[25], but contradicts another supporting a phylogenetic affinity between Soricidae and Talpidae using 26 nuclear genes[31]
Previous studies might have encountered the long-branch attraction (LBA)[32] problem because only one or two representative species of each family separated by long branches were examined
We conducted analyses using all of the major lineages in Eulipotyphla at the subfamilial level, making the phylogenetic analyses less vulnerable to the LBA problem for inter-familial relationships
Summary
The divergence time between the Cuban and Hispaniolan solenodons was estimated to be 25 Ma (95% credibility interval [CI] = 16–38 Ma) based on a molecular chronological analysis of mitochondrial DNA (mtDNA) using old museum specimens[25]. Roca et al.[25] indicated that there is consistency between the molecular estimate and geological evidence that the separation between Cuba and Hispaniola occurred at 25–27 Ma7 and suggested that the two solenodon species could have originated via a vicariance event. Our analysis of the phylogenetic relationships and divergence times using a molecular supermatrix composed of the five nuclear gene exon sequences provided evidence supporting over-water dispersal, rather than vicariance, for the origin of the family Solenodontidae in the Paleocene and the Cuban solenodon in the Early Pliocene
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