Genetic divergence between two phenotypically distinct bottlenose dolphin ecotypes suggests separate evolutionary...

Area of Science:

• Marine Biology
• Genetics
• Conservation Science

Background:

• Bottlenose dolphins exhibit morphological variation globally, with recognized coastal and offshore ecotypes in many regions.
• Limited data exists on Southwest Atlantic bottlenose dolphin ecotypes and their genetic connectivity.
• Morphological differences suggest distinct populations, but genetic evidence is needed.

Purpose of the Study:

• To analyze genetic variability and population structure between coastal and offshore bottlenose dolphins in the Southwest Atlantic.
• To determine if observed morphological distinctions align with genetic differentiation.
• To assess connectivity and evolutionary trajectories of these ecotypes.

Main Methods:

• Mitochondrial DNA (mtDNA) control region sequences were analyzed.
• Microsatellite genotypes were used to infer population structure.
• Genetic diversity and differentiation (FST, ΦST) were calculated for both marker types.

Main Results:

• Strong genetic structuring was found between coastal and offshore ecotypes (microsatellites FST = 0.385, mtDNA FST = 0.183).
• Coastal ecotypes exhibited significantly lower genetic diversity than offshore ecotypes.
• Minimal current and historical gene flow was detected between the two ecotypes.

Conclusions:

• Genetic findings support distinct evolutionary trajectories for coastal and offshore bottlenose dolphins in the Southwest Atlantic.
• The offshore ecotype is recommended as an additional Evolutionarily Significant Unit (ESU).
• Results have implications for the conservation management of bottlenose dolphins in the region.