scholarly journals No leading‐edge effect in North Atlantic harbor porpoises: Evolutionary and conservation implications

2021 ◽  
Author(s):  
Yacine Ben Chehida ◽  
Roisin Loughnane ◽  
Julie Thumloup ◽  
Kristin Kaschner ◽  
Cristina Garilao ◽  
...  
2020 ◽  
Author(s):  
Yacine Ben Chehida ◽  
Roisin Loughnane ◽  
Julie Thumloup ◽  
Kristin Kaschner ◽  
Cristina Garilao ◽  
...  

AbstractUnderstanding a species response to past environmental changes can help forecast how they will cope with ongoing climate changes. Harbor porpoises are widely distributed in the North Atlantic and were deeply impacted by the Pleistocene changes with the split of three sub-species. Despite major impacts of fisheries on natural populations, little is known about population connectivity and dispersal, how they reacted to the Pleistocene changes and how they will evolve in the future. Here, we used phylogenetics, population genetics, and predictive habitat modelling to investigate population structure and phylogeographic history of the North Atlantic porpoises. A total of 925 porpoises were characterized at 10 microsatellite loci and one-quarter of the mitogenome (mtDNA). A highly divergent mtDNA lineage was uncovered in one porpoise off Western Greenland, suggesting that a cryptic group may occur and could belong to a recently discovered mesopelagic ecotype off Greenland. Aside from it and the southern sub-species, spatial genetic variation showed that porpoises from both sides of the North Atlantic form a continuous system belonging to the same subspecies (Phocoena phocoena phoceona). Yet, we identified important departures from random mating and restricted intergenerational dispersal forming a highly significant isolation-by-distance (IBD) at both mtDNA and nuclear markers. A ten times stronger IBD at mtDNA compared to nuclear loci supported previous evidence of female philopatry. Together with the lack of spatial trends in genetic diversity, this IBD suggests that migration-drift equilibrium has been reached, erasing any genetic signal of a leading-edge effect that accompanied the predicted recolonization of the northern habitats freed from Pleistocene ice. These results illuminate the processes shaping porpoise population structure and provide a framework for designing conservation strategies and forecasting future population evolution.


2007 ◽  
Vol 48 ◽  
pp. 790 ◽  
Author(s):  
Feng Xu ◽  
John C. Patterson ◽  
Chengwang Lei
Keyword(s):  

1991 ◽  
Author(s):  
K. HEFFNER ◽  
L. GOTTESDIENER ◽  
A. CHPOUN ◽  
J. LENGRAND

1995 ◽  
Vol 293 ◽  
pp. 181-206 ◽  
Author(s):  
A. B. Parry

An asymptotic frequency-domain approach is used to describe the radiation from a supersonic swept propeller within the framework of linear acoustics. With this approach the radiation of singularities, their points of origin on the blades, and their relation to blade geometry and loading are easily obtained. In particular, it is shown that a swept propeller with a completely subsonic leading edge can still radiate singularities, if the leading edge is blunt, due to a supersonic edge effect at the blade tips. In addition, the radiation from a family of ‘critical’ swept-blade designs is shown to be more singular than that from a straight-bladed design. Numerical and asymptotic results for such designs show that the peak radiation is, typically, increased by 5–10 dB.


1956 ◽  
Vol 26 (4) ◽  
pp. 241-246 ◽  
Author(s):  
A. G. HAMMITT ◽  
S. M. BOGDONOFF
Keyword(s):  

2021 ◽  
Author(s):  
Patrick G.R. Jodice ◽  
Pamela E. Michael ◽  
Jeffrey S. Gleason ◽  
J. Christopher Haney ◽  
Yvan G. Satgé

ABSTRACTThe black-capped petrel (Pterodroma hasitata) is an endangered seabird endemic to the western north Atlantic. Although estimated at ~ 1,000 breeding pairs, only ~ 100 nests have been located at two sites in Haiti and three sites in the Dominican Republic. At sea, the species primarily occupies waters of the western Gulf Stream in the Atlantic and the Caribbean Sea. Due to limited data, there is currently not a consensus on the marine range of the species. There are several maps in use for the marine range of the species and these differ with respect to the north, south, and eastward extent of the range. None of these maps, however, includes the Gulf of Mexico. Here, we report on observations of black-capped petrels during two vessel-based survey efforts throughout the northern Gulf of Mexico from July 2010 - July 2011, and from April 2017 - September 2019. During the 558 days and 54.7 km of surveys from both efforts we tallied 40 black-capped petrels. Most observations occurred in the eastern Gulf, although birds were observed over much of the east-west and north-south footprint of the survey area. Predictive models indicated that habitat suitability for black-capped petrels was highest in areas associated with dynamic waters of the Loop Current, similar to habitat used along the western edge of the Gulf Stream in the western north Atlantic. We suggest that the range for black-capped petrels be modified to include the entire northern Gulf of Mexico although distribution may be more clumped in the eastern Gulf and patchier elsewhere. It remains unclear, however, which nesting areas are linked to the Gulf of Mexico.


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