Interspecific Hybridization in Pilot Whales and Asymmetric Genetic Introgression in Northern Globicephala melas under the Scenario of Global Warming

Abstract

Pilot whales are two cetacean species (Globicephala melas and G. macrorhynchus) whose distributions are correlated with water temperature and partially overlap in some areas like the North Atlantic Ocean. In the context of global warming, distribution range shifts are expected to occur in species affected by temperature. Consequently, a northward displacement of the tropical pilot whale G. macrorynchus is expected, eventually leading to increased secondary contact areas and opportunities for interspecific hybridization. Here, we describe genetic evidences of recurrent hybridization between pilot whales in northeast Atlantic Ocean. Based on mitochondrial DNA sequences and microsatellite loci, asymmetric introgression of G. macrorhynchus genes into G. melas was observed. For the latter species, a significant correlation was found between historical population growth rate estimates and paleotemperature oscillations. Introgressive hybridization, current temperature increases and lower genetic variation in G. melas suggest that this species could be at risk in its northern range. Under increasing environmental and human-mediated stressors in the North Atlantic Ocean, it seems recommendable to develop a conservation program for G. melas.

Complex biogeographical patterns support an ecological connectivity network of a large marine predator in the north‐east Atlantic

“…Such a spatial component is consistent with some degree of population structuring, which combined with the connectivity network (between some of the areas/archipelagos and an outside area) suggest that short‐finned pilot whales have developed a complex social and geographical ecology. Although the social analysis has showed that none of the clusters composed by the individuals captured in Madeira and the Azores were linked to the clusters composed by the individuals captured in Madeira and the Canaries, the absence of genetic population differentiation in this species in the study area (Alves, Quérouil, et al., ; Miralles et al., ) suggests that it may be an artefact of an insufficient sample size and that it supports the findings described here. Ecological spatial structuring has been also suggested for other delphinid populations occupying large areas, that is, over hundreds or thousands of kilometres.…”

“…To estimate residency times, we applied the initial models developed by Whitehead (). These models provided an opportunity to analyse movements into and out of each archipelago, which is known to occupy only a portion of the animals’ range (Alves, Quérouil, et al., ; Miralles, Oremus, Silva, Planes, & Garcia‐Vazquez, ).…”

Global phylogeography and genetic diversity of the long-finned pilot whale Globicephala melas, with new data from the southeastern Pacific

“…After adding previously published sequences from other oceanic basins 20,[23][24][25][26] , a total of 15 haplotypes were obtained after the elimination of the site that was generating phylogeographic noise in the total 1012 sequences. This led to the combination of four previously described haplotypes in the following pairs: S with R, P with U, Q with Y, and E with G ( Table 1).…”

“…A colonization event from south to north would have taken place through a founder effect, followed by demographic population growth. Additional genetic research on pilot whales has been conducted mostly at the population level in the North Atlantic and Mediterranean Sea [23][24][25] , however, an integration of this available information is missing, together with the sampling of other areas such as the southeastern Pacific.…”

Do bigger bodies require bigger radiators? Insights into thermal ecology from closely related marine mammal species and implications for ecogeographic rules

“…importance of cruising vs. maneuverability for different foraging behaviours) in assessing differences in the size of their appendages (Berta, Sumich, & Kovacs, ; Domenici, ; Woodward, Winn, & Fish, ). However, short‐finned pilot whales and long‐finned pilot whales are closely related species that diverged only about 648,500 years ago (Miralles, Oremus, Silva, Planes, & Garcia‐Vasquez, ) and are generally similar morphologically, but show contrasting distributions in the North Atlantic Ocean (Hayes, Josephson, Maze‐Foley, & Rosel, ; Figure ). Short‐finned pilot whales occur in tropical and subtropical waters, while long‐finned pilot whales show a more temperate distribution (Leatherwood, Caldwell, & Winn, ).…”