Ecological Niche Modeling of Three Species of Stenella Dolphins in the Caribbean Basin, With Application to the Seaflower Biosphere Reserve

Dolphins of the genus Stenella occur in pelagic waters of both tropical and warm-temperate oceans. Three species, the Atlantic spotted dolphin (Stenella frontalis), the pantropical spotted dolphin (S. attenuata), and the spinner dolphin (S. longirostris) are abundant worldwide, but in the Caribbean Basin they have been poorly studied and information on their distribution patterns is scarce. Specifically, in Colombia’s remote Seaflower Biosphere Reserve (SFBR) S. attenuata has been reported occasionally, but S. frontalis and S. longirostris have never been recorded before. To address this information gap, an ecological niche modeling approach was used to determine the potential distribution patterns of these three dolphin species in the region. Records of these species for the Caribbean Basin were compiled, including both published and unpublished data. Environmental information, including bathymetry, bathymetric slope, distance to shore, sea surface temperature, sea surface salinity, and chlorophyll-a concentration was gathered from public databases (MARSPEC and Bio-ORACLE) in raster format. The maximum entropy algorithm (Maxent) for modeling species’ geographic distributions with presence-only data was used. After filtering the data, 210 records of S. attenuata, 204 of S. frontalis, and 80 of S. longirostris were used to run models. The best configuration for each model was chosen based on the ΔAICc criterion. For all three species, the final ecological niche models returned AUC test values higher than 0.8, indicating satisfactory model performance. The resulting potential distribution maps suggested that areas closest to continental shorelines of the Caribbean Basin and surrounding islands had the highest environmental suitability for all species (>70%). All models reported high environmental suitability for S. attenuata and S. longirostris in the SFBR, mainly in the southernmost part surrounding San Andrés and Providence Archipelago. Assessment of niche overlap from the predictions of species distributions using the similarity statistic and pairwise map overlap indicated that S. frontalis and S. longirostris had niches slightly more similar in comparison to S. attenuata. As this was a first effort to fill a gap in our understanding of the distribution of species in the genus Stenella in the Caribbean Basin, further studies are necessary using both niche modeling and biological/ecological approaches

Range extension for the common dolphin (Delphinus sp.) to the Colombian Caribbean, with taxonomic implications from genetic barcoding and phylogenetic analyses.

The nearest known population of common dolphins (Delphinus sp.) to the Colombian Caribbean occurs in a fairly restricted range in eastern Venezuela. These dolphins have not been previously reported in the Colombian Caribbean, likely because of a lack of study of the local cetacean fauna. We collected cetacean observations in waters of the Guajira Department, northern Colombia (~11°N, 73°W) during two separate efforts: (a) a seismic vessel survey (December 2009-March 2010), and (b) three coastal surveys from small boats (May-July 2012, May 2013, and May 2014). Here we document ten sightings of common dolphins collected during these surveys, which extend the known range of the species by ~1000 km into the southwestern Caribbean. We also collected nine skin biopsies in 2013 and 2014. In order to determine the taxonomic identity of the specimens, we conducted genetic barcoding and phylogenetic analyses using two mitochondrial markers, the Control Region (mtDNA) and Cytochrome b (Cytb). Results indicate that these specimens are genetically closer to the short-beaked common dolphin (Delphinus delphis) even though morphologically they resemble a long-beaked form (Delphinus sp.). However, the specific taxonomic status of common dolphins in the Caribbean and in the Western Atlantic remains unresolved. It is also unclear whether the distribution of the species between northern Colombia and eastern Venezuela is continuous or disjoined, or whether they can be considered part of the same stock

Common dolphins sighting data (date, location and water depth).

<p>Common dolphins sighting data (date, location and water depth).</p

Photographs of common dolphins (<i>Delphinus</i> sp.) taken in the northern Colombia.

<p>These photos were taken the 9^th and 17^th May 2012 off the lower Guajira Peninsula near Mingueo, municipality of Dibulla. The diagnostic external morphology and coloration pattern of the genus are evident in all images. In addition, although the pattern is rather muted, note how the tan-coloured thoracic patch is interrupted by a secondary dark stripe that runs forward and upward from the eye-to-anus stripe.</p

Phylogenetic reconstruction of common dolphins Cytochrome <i>b</i> (Cyt<i>b</i>) worldwide haplotypes.

<p>Cyt<i>b</i> haplotype identified insamples from La Guajira is highlighted in grey.</p

Tree based on the Surveillance barcoding results with the D-loop gene.

<p>Sequences obtained from samples from La Guajira (user sequence) showed affinity with the reference sequences. Evolutionary distance with D-loop sequences ranged between 0.0179 and 0.023 changes/site for short-beaked common dolphins and between 0.0333 and 0.0385 changes/site for long-beaked common dolphins. Values below the branches correspond to neighbor-joining (NJ) bootstrap support values [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0171000#pone.0171000.ref032" target="_blank">32</a>].</p

Published sequences of common dolphins used in this study for Cyt<i>b</i> and Control Region (D-loop).

<p>Published sequences of common dolphins used in this study for Cyt<i>b</i> and Control Region (D-loop).</p

Phylogenetic reconstruction of common dolphins Control Region (D-loop) worldwide haplotypes.

<p>Control Region (D-loop) haplotypes identified in samples from La Guajira are highlighted in grey.</p

Location of the first records of common dolphins (<i>Delphinus</i> sp.) in the Colombian Caribbean.

<p>Map A shows the potential distribution area of possible Guajira´s stock and the range of the Venezuelan Stock. Map B shows sightings of common dolphins in the Guajira Peninsula. Green symbols indicate strandings, red symbols indicate sightings collected from a seismic vessel, and the yellow symbols indicate sightings collected during small-boat coastal surveys.</p

DNA Surveillance barcoding results with the Cytb gene.

<p>Sequences obtained from samples from La Guajira (user sequence) showed affinity with the reference sequences. Evolutionary distance with Cytb sequences ranged between 0.0197 and 0.0228 changes/site for short-beaked common dolphins (<i>Delphinus delphis</i>). Values below the branches correspond to neighbor-joining (NJ) bootstrap support values [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0171000#pone.0171000.ref032" target="_blank">32</a>].</p