Seascape Genetics of the Atlantic Spotted Dolphin (Stenella frontalis) Based on Mitochondrial DNA

Abstract

The Atlantic spotted dolphin (Stenella frontalis) is endemic to tropical, subtropical, and warm temperate waters of the Atlantic Ocean. Throughout its distribution, both geographic distance and environmental variation may contribute to population structure of the species. In this study we follow a seascape genetics approach to investigate population differentiation of Atlantic spotted dolphins based on a large worldwide dataset and the relationship with marine environmental variables. The results revealed that the Atlantic spotted dolphin exhibits population genetic structure across its distribution based on mitochondrial DNA control region (mtDNA-CR) data. Analyses based on the contemporary landscape suggested, at both the individual and population-level, that the population genetic structure is consistent with the isolation-by-distance model. However, because geography and environmental matrices were correlated, and because in some, but not all analyses, we found a significant effect for the environment, we cannot rule out the addition contribution of environmental factors in structuring genetic variation. Future analyses based on nuclear data are needed to evaluate whether local processes, such as social structure and some level of philopatry within populations, may be contributing to the associations among genetic structure, geographic, and environmental distance.

Mitochondrial Variation of Bottlenose Dolphins (Tursiops truncatus) from the Canary Islands Suggests a Key Population for Conservation with High Connectivity within the North-East Atlantic Ocean

“…However, just three species dominated the sightings: bottlenose dolphins, pilot whales ( Globicephala macrorhynchus ) and spotted dolphins ( Stenella frontalis ) [ 53 ]. Comparing the results obtained here with these other two delphinid species, we observed the same lack of genetic structuring across the Canary Islands in spotted dolphins [ 54 ] but not in pilot whales [ 52 ]. On a broader scale, it has been described that spotted dolphins represent several distinct units in the Atlantic Ocean: Macaronesian group clustering, Canary Islands, Azores and Madeiran individuals [ 54 ].…”

More pieces for the puzzle: novel information on the genetic diversity and population structure of Steno bredanensis (Artiodactyla: Delphinidae) in Central America and the Caribbean Sea

“…The genetic differentiation observed between rough-toothed dolphins from the Caribbean and North Atlantic Ocean with Brazil-South Atlantic Ocean had been previously described (Donato et al, 2019;Silva et al, 2015), and agrees with other genetic studies with delphinids such as the Atlantic spotted dolphin Stenella frontalis (Cuvier, 1829) (do Amaral et al, 2021), bottlenose dolphin (Fruet et al, 2014), clymene dolphin Stenella clymene (Gray, 1850) (Nara et al, 2017), and common dolphin (Amaral et al, 2012), which reported a similar isolation pattern. Oceanographical features like the Amazon River mouth and the North Brazilian Current appear to act as a barrier that is segregating fauna from the northern and southern Brazil (Costa et al, 2017).…”

Latin American aquatic mammals: an overview of 12 years focusing on molecular techniques applied to conservation

“…Southeastern Brazil did not show significant differentiation when compared to the Azores and Madeira. In a recent study that included a higher number of mtDNA sequences from both the Caribbean and from northeastern and southeastern Brazil as well as from Uruguay, population structure was found between a group of samples from oceanic origins: those from Azores, Madeira, the Canary Islands and the Mid-Atlantic Bight; those from the Caribbean and northeastern Brazil; and those from southeastern Brazil and Uruguay (do Amaral et al, 2021). Such population differentiation pattern could be explained due to isolation by distance, in which genetic distance can be correlated with the geographic distance between sample locations.…”