Evidence of range contraction and increased metapopulation patchiness of the rare eastern Nearctic Karst Snowfly Allocapnia cunninghami Ross & Ricker, 1971

2021 ◽  
Author(s):  
Scott A. Grubbs
Keyword(s):  
Range Contraction

Ongoing population decline and range contraction in Norwegian forest grouse

2009 ◽  
Vol 32 (0) ◽  
pp. 179 ◽  
Author(s):  
Finn Gregersen ◽  
Håkon Gregersen
Keyword(s):  
Population Decline ◽  
Range Contraction

Prey availability modulates predicted range contraction of two large felids in response to changing climate

2021 ◽  
Vol 255 ◽  
pp. 109018
Author(s):  
Rasoul Khosravi ◽  
Mahmoud-Reza Hemami ◽  
Shima Malakoutikhah ◽  
Mohammad Reza Ashrafzadeh ◽  
Samuel A. Cushman
Keyword(s):  
Prey Availability ◽  
Range Contraction ◽  
Changing Climate

scholarly journals Overfishing and habitat loss drive range contraction of iconic marine fishes to near extinction

2021 ◽  
Vol 7 (7) ◽  
pp. eabb6026
Author(s):  
Helen F. Yan ◽  
Peter M. Kyne ◽  
Rima W. Jabado ◽  
Ruth H. Leeney ◽  
Lindsay N.K. Davidson ◽  
...  
Keyword(s):  
Habitat Loss ◽  
Coastal Waters ◽  
Marine Fishes ◽  
Similar Species ◽  
Range Contraction ◽  
Historical Distribution ◽  
Local Extinctions ◽  
Near Extinction ◽  
Over Time

Extinctions on land are often inferred from sparse sightings over time, but this technique is ill-suited for wide-ranging species. We develop a space-for-time approach to track the spatial contraction and drivers of decline of sawfishes. These iconic and endangered shark-like rays were once found in warm, coastal waters of 90 nations and are now presumed extinct in more than half (n = 46). Using dynamic geography theory, we predict that sawfishes are gone from at least nine additional nations. Overfishing and habitat loss have reduced spatial occupancy, leading to local extinctions in 55 of the 90 nations, which equates to 58.7% of their historical distribution. Retention bans and habitat protections are urgently necessary to secure a future for sawfishes and similar species.

Modes of extinction, pseudo-extinction and distribution in Middle Jurassic ammonites: terminology

2001 ◽  
Vol 38 (2) ◽  
pp. 187-195
Author(s):  
Gerd EG Westermann
Keyword(s):  
New Species ◽  
Sea Level ◽  
Middle Jurassic ◽  
Small Populations ◽  
Sea Level Changes ◽  
Range Contraction ◽  
Extreme Form ◽  
Phylogenetic Lineage

Mid-Jurassic Ammonitina (Cephalopoda, Mollusca) provide good examples of true and apparent "extinctions" (i.e., taxon or clade disappearances) at the local, regional, and global scales. A terminology is presented. Extinction is the termination of a phylogenetic lineage or entire clade (not of local demes or regional populations). Extinction was often preceded by progressive range contraction that resulted in diachronous regional disappearance ("extirpation") and occurred with the elimination of the last refuge. Other range contractions, however, were not terminal, but were followed by renewed expansions, resulting in temporary absence of the lineage over part of its known range only, due to pseudo-extinction. Some lineages, called Lazarus taxa, apparently disappeared entirely for short or extended periods by pseudotermination (causing a "phylogenetic hiatus"). This is an extreme form of pseudo-extinction with unknown refuge due to small size and (or) unsuitable facies and location. Lineage or clade reappearance may be in the form of new species, whose relationship to ancestral taxa has been problematic. Some disappearances can be explained with displacive competition, where the replacement taxon is either of endemic origin or an immigrant. Recent research in previously underexplored field areas has closed some of the gaps of documentation by finding the refuges. Range contractions and expansions, together with their regional disappearances and pseudo-extinctions, including pseudotermination, were often causally related to sea-level changes, especially eustasy. Most true extinctions, however, cannot be identified precisely, because they occurred in small populations and (or) refuges. Extinctions presumably did not coincide with global geoevents.

scholarly journals Range reduction of the Oblong Rocksnail, Leptoxis compacta, shapes riverscape genetic patterns

2020 ◽  
Author(s):  
Aaliyah D. Wright ◽  
Nicole L. Garrison ◽  
Ashantye’ S. Williams ◽  
Paul D. Johnson ◽  
Nathan V. Whelan
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Human Impacts ◽  
Isolation By Distance ◽  
Extinction Risk ◽  
River System ◽  
High Genetic Diversity ◽  
Range Contraction ◽  
Genetic Patterns ◽  
Cahaba River

AbstractMany freshwater gastropod species face extinction, including 79% of species in the family Pleuroceridae. The Oblong Rocksnail, Leptoxis compacta, is a narrow range endemic pleurocerid from the Cahaba River basin in central Alabama that has seen rapid range contraction in the last 100 years. Such a decline is expected to negatively affect genetic diversity in the species. However, precise patterns of genetic variation and gene flow across the restricted range of L. compacta are unknown. This lack of information limits our understanding of human impacts on the Cahaba River system and Pleuroceridae. Here, we show that L. compacta has likely seen a species-wide decline in genetic diversity, but remaining populations have relatively high genetic diversity. We also report a contemporary range extension compared to the last published survey. Leptoxis compacta does not display an isolation by distance pattern, contrasting patterns seen in many riverine taxa. Our findings also indicate that historical range contraction has resulted in the absence of common genetic patterns seen in many riverine taxa like isolation by distance as the small distribution of L. compacta allows for relatively unrestricted gene flow across its remaining range despite limited dispersal abilities. Two collection sites had higher genetic diversity than others, and broodstock sites for future captive propagation and reintroduction efforts should utilize sites identified here as having the highest genetic diversity. Broadly, our results support the hypothesis that range contraction will result in the reduction of species-wide genetic diversity, and common riverscape genetic patterns cannot be assumed to be present in species facing extinction risk.

scholarly journals Range reduction of Oblong Rocksnail, Leptoxis compacta, shapes riverscape genetic patterns

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9789
Author(s):  
Aaliyah D. Wright ◽  
Nicole L. Garrison ◽  
Ashantye’ S. Williams ◽  
Paul D. Johnson ◽  
Nathan V. Whelan
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Human Impacts ◽  
Isolation By Distance ◽  
Extinction Risk ◽  
River System ◽  
High Genetic Diversity ◽  
Range Contraction ◽  
Genetic Patterns ◽  
Cahaba River

Many freshwater gastropod species face extinction, including 79% of species in the family Pleuroceridae. The Oblong Rocksnail, Leptoxis compacta, is a narrow range endemic pleurocerid from the Cahaba River basin in central Alabama that has seen rapid range contraction in the last 100 years. Such a decline is expected to negatively affect genetic diversity in the species. However, precise patterns of genetic variation and gene flow across the restricted range of L. compacta are unknown. This lack of information limits our understanding of human impacts on the Cahaba River system and Pleuroceridae. Here, we show that L. compacta has likely seen a species-wide decline in genetic diversity, but remaining populations have relatively high genetic diversity. We also report a contemporary range extension compared to the last published survey. Our findings indicate that historical range contraction has resulted in the absence of common genetic patterns seen in many riverine taxa like isolation by distance as the small distribution of L. compacta allows for relatively unrestricted gene flow across its remaining range despite limited dispersal abilities. Two collection sites had higher genetic diversity than others, and broodstock sites for future captive propagation and reintroduction efforts should utilize sites identified here as having the highest genetic diversity. Broadly, our results support the hypothesis that range contraction will result in the reduction of species-wide genetic diversity, and common riverscape genetic patterns cannot be assumed to be present in species facing extinction risk.

scholarly journals Range contraction in large pelagic predators

2011 ◽  
Vol 108 (29) ◽  
pp. 11942-11947 ◽  
Author(s):  
B. Worm ◽  
D. P. Tittensor
Keyword(s):  
Range Contraction

scholarly journals Range contraction enables harvesting to extinction

2017 ◽  
Vol 114 (15) ◽  
pp. 3945-3950 ◽  
Author(s):  
Matthew G. Burgess ◽  
Christopher Costello ◽  
Alexa Fredston-Hermann ◽  
Malin L. Pinsky ◽  
Steven D. Gaines ◽  
...  
Keyword(s):  
Predator Avoidance ◽  
Geographic Area ◽  
Economic Incentives ◽  
Aquatic Species ◽  
Range Contraction ◽  
Patchy Environments ◽  
Price Increases ◽  
Declining Populations ◽  
Local Densities ◽  
Declining Species

Economic incentives to harvest a species usually diminish as its abundance declines, because harvest costs increase. This prevents harvesting to extinction. A known exception can occur if consumer demand causes a declining species’ harvest price to rise faster than costs. This threat may affect rare and valuable species, such as large land mammals, sturgeons, and bluefin tunas. We analyze a similar but underappreciated threat, which arises when the geographic area (range) occupied by a species contracts as its abundance declines. Range contractions maintain the local densities of declining populations, which facilitates harvesting to extinction by preventing abundance declines from causing harvest costs to rise. Factors causing such range contractions include schooling, herding, or flocking behaviors—which, ironically, can be predator-avoidance adaptations; patchy environments; habitat loss; and climate change. We use a simple model to identify combinations of range contractions and price increases capable of causing extinction from profitable overharvesting, and we compare these to an empirical review. We find that some aquatic species that school or forage in patchy environments experience sufficiently severe range contractions as they decline to allow profitable harvesting to extinction even with little or no price increase; and some high-value declining aquatic species experience severe price increases. For terrestrial species, the data needed to evaluate our theory are scarce, but available evidence suggests that extinction-enabling range contractions may be common among declining mammals and birds. Thus, factors causing range contraction as abundance declines may pose unexpectedly large extinction risks to harvested species.

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