Abstract
Spinner dolphins (Stenella longirostris, Gray 1828) are widely distributed in tropical waters around the world. Although they occur in large, pelagic groups in the Eastern Tropical Pacific, elsewhere in the Pacific they are found in small and genetically isolated populations associated with islands. This species is considered to be “Least Concern” (LC) by the World Conservation Union (IUCN). To assess genetic diversity and population structure of an island-associated population in the South Atlantic Ocean we surveyed 162 spinner dolphins throughout the Fernando de Noronha Archipelago of the northeast coast of Brazil using ten microsatellite loci and sequencing a 413-bp section of the mitochondrial DNA (mtDNA) control region. Eleven mtDNA haplotypes were identified and haplotype diversity (h) and nucleotide diversity (π) were 0.3747 and 0.0060, respectively. Median-Joining Network revealed the presence of two very divergent haplotypes and F-statistics indicated some heterogeneity between two sampling years. All microsatellite loci were polymorphic (Ho: 0.767; He: 0,764) but, revealed no detectable substructure. We also compared the mtDNA haplotypes from Noronha to 159 haplotypes representing 893 individuals from 14 locations worldwide. We found that the two common haplotypes from the Fernando de Noronha Archipelago were absent in all other populations. These comparisons showed that Noronha spinner dolphins are likely more differentiated than other island populations, suggesting that they form societies with strong site fidelity mediated by females.
Highlights
The spinner dolphin (Stenella longirostris, Gray 1828) is widely distributed in tropical waters around the world [1,2,3,4]
We examine sequences of mitochondrial DNA and 10 microsatellite loci to evaluate the genetic diversity of this species in the Fernando de Noronha Archipelago, and test the hypothesis of the existence of genetic structuring in the South Atlantic Ocean and haplotypes sharing among individuals from different oceans
From the analysis of 162 individuals, we identified the sex of 137 individuals (84 males and 53 females)
Summary
The spinner dolphin (Stenella longirostris, Gray 1828) is widely distributed in tropical waters around the world [1,2,3,4]. Gray’s spinner dolphins (here after referred to as spinner dolphins) are found in oceanic waters of the Atlantic, Pacific and Indian oceans, and around volcanic islands and atolls, such as those of Hawaii, French Polynesia and Fernando de Noronha [7,8,9]. These dolphins can travel great distances (from 300 to 1000 miles) and are able to disperse between islands and atolls [10,11,12,13]. Large dispersal could have contributed to the high levels of genetic divergence exhibited by this species (around the world) [2,3,4,14]
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have