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 ◽  
...  
Keyword(s):  
Edge Effect ◽  
North Atlantic ◽  
Leading Edge ◽  
Conservation Implications ◽  
Harbor Porpoises

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

2020 ◽  
Author(s):  
Yacine Ben Chehida ◽  
Roisin Loughnane ◽  
Julie Thumloup ◽  
Kristin Kaschner ◽  
Cristina Garilao ◽  
...  
Keyword(s):  
Population Structure ◽  
Edge Effect ◽  
North Atlantic ◽  
Environmental Changes ◽  
Isolation By Distance ◽  
Leading Edge ◽  
Species Response ◽  
The North ◽  
The North Atlantic ◽  
Harbor Porpoises

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.

The leading edge effect in a suddenly differentially heated cavity

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

Leading edge effect on rarefied hypersonic flow over a flat plate

1991 ◽  
Author(s):  
K. HEFFNER ◽  
L. GOTTESDIENER ◽  
A. CHPOUN ◽  
J. LENGRAND
Keyword(s):  
Flat Plate ◽  
Hypersonic Flow ◽  
Edge Effect ◽  
Leading Edge

The effect of blade sweep on the reduction and enhancement of supersonic propeller noise

1995 ◽  
Vol 293 ◽  
pp. 181-206 ◽  
Author(s):  
A. B. Parry
Keyword(s):  
Frequency Domain ◽  
Edge Effect ◽  
Leading Edge ◽  
Asymptotic Results ◽  
Propeller Noise ◽  
Frequency Domain Approach ◽  
Blade Geometry ◽  
Blade Tips

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.

Hypersonic Studies of the Leading Edge Effect on the Flow Over a Flat Plate

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

scholarly journals Expanding the marine range of the endangered black-capped petrel Pterodroma hasitata: Occurrence in the northern Gulf of Mexico and conservation implications

2021 ◽  
Author(s):  
Patrick G.R. Jodice ◽  
Pamela E. Michael ◽  
Jeffrey S. Gleason ◽  
J. Christopher Haney ◽  
Yvan G. Satgé
Keyword(s):  
Gulf Of Mexico ◽  
North Atlantic ◽  
Gulf Stream ◽  
Loop Current ◽  
Limited Data ◽  
Northern Gulf Of Mexico ◽  
The North ◽  
Conservation Implications ◽  
The Caribbean ◽  
East West

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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