Population declines, genetic bottlenecks and potential hybridization in sea snakes on Australia's Timor Sea reefs

2018 ◽  
Vol 225 ◽  
pp. 66-79 ◽  
Author(s):  
Vimoksalehi Lukoschek
2018 ◽  
Vol 285 (1884) ◽  
pp. 20181148 ◽  
Author(s):  
Christophe Dufresnes ◽  
Christian Miquel ◽  
Nadège Remollino ◽  
François Biollaz ◽  
Nicolas Salamin ◽  
...  

Genetic bottlenecks resulting from human-induced population declines make alarming symbols for the irreversible loss of our natural legacy worldwide. The grey wolf ( Canis lupus ) is an iconic example of extreme declines driven by anthropogenic factors. Here, we assessed the genetic signatures of 150 years of wolf persecution throughout the Western Palaearctic by high-throughput mitochondrial DNA sequencing of historical specimens in an unprecedented spatio-temporal framework. Despite Late Pleistocene bottlenecks, we show that historical genetic variation had remained high throughout Europe until the last several hundred years. In Western Europe, where wolves nearly got fully exterminated, diversity dramatically collapsed at the turn of the twentieth century and recolonization from few homogeneous relict populations induced drastic shifts of genetic composition. By contrast, little genetic displacement and steady levels of diversity were maintained in Eastern European regions, where human persecution had lesser effects on wolf demography. By comparing prehistoric, historic and modern patterns of genetic diversity, our study hence traces the timeframe and the active human role in the decline of the grey wolf, an emblematic yet controversial animal which symbolizes the complex relationship between human societies and nature conservation.


2021 ◽  
Vol 8 ◽  
Author(s):  
Ruchira Somaweera ◽  
Vinay Udyawer ◽  
Michael L. Guinea ◽  
Daniela M. Ceccarelli ◽  
Rohan H. Clarke ◽  
...  

Over the past decade, vertebrate populations globally have experienced significant declines in distribution and abundance. Understanding the reasons behind these population declines is the first step in implementing appropriate management responses to improve conservation outcomes. Uncovering drivers of extirpation events after the fact, however, requires a careful forensic approach to prevent similar declines elsewhere. The once abundant and species-rich sea snake fauna of Ashmore Reef Marine Park, in the Timor Sea, collapsed dramatically in the early 2000s. No such decline has occurred on surrounding reefs. We synthesise the evidence for this collapse and the subsequent slow recovery and evaluate the plausibility of potential drivers for the declines, as well as provide evidence against certain explanations that have been proposed in the past. Our systematic review shows that of seven possible hypotheses considered, at least three are credible and require additional information: (1) stochastic environmental events may have increased the snakes’ susceptibility to pathogens, (2) a resurgence in the abundance of top predators may have induced a localised change in trophic structure, and (3) an acute increase in local boat traffic may have had negative physical impacts. One or more of these factors, possibly acting in combination with as yet other unidentified factors, is the most plausible explanation for the precipitous decline in sea snake populations observed. Based on this position, we identify future research directions with a focus on addressing critical gaps in knowledge to inform and prioritise future management actions.


Forests ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 496
Author(s):  
Grace L. Parikh ◽  
Christopher R. Webster

Ungulate herbivory occurring within a forest plant community’s natural range of variation may help maintain species diversity. However, acute or chronically elevated levels of herbivory can produce dramatic changes in forest communities. For example, chronically high levels of herbivory by white-tailed deer (Odocoileus virginianus Zimmerman) in regions of historically low abundance at northern latitudes have dramatically altered forest community composition. In eastern hemlock (Tsuga canadensis L. Carrière) stands where deer aggregate during winter, high deer use has been associated with a shift towards deciduous species (i.e., maples [Acer spp.]) dominating the regeneration layer. Especially harsh winters can lead to deer population declines, which could facilitate regeneration of species that have been suppressed by browsing, such as hemlock. To enhance our understanding of how fluctuations in herbivory influence regeneration dynamics, we surveyed regeneration and deer use in 15 relict hemlock stands in the western Upper Peninsula of Michigan in 2007 and again in 2015. With the exception of small seedlings (0.04–0.24 m height), primarily maples whose abundance increased significantly (p < 0.05), we observed widespread significant declines (p < 0.05) in the abundance of medium (0.25 ≤ 1.4 m height) and large regeneration (>1.4 m tall ≤ 4 cm diameter at breast height) over the study period. Midway through our study period, the region experienced a high severity winter (i.e., “polar vortex”) which resulted in a substantial decline in the white-tailed deer population. Given the dominance of maples and dearth of hemlock in the seedling layer, the decline in the deer population may fail to forestall or possibly hasten the trend towards maple dominance of the regeneration layer as these stands recover from pulses of acute herbivory associated with high-severity winters and the press of chronically high herbivory that precedes them.


Biology ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 693
Author(s):  
Danilo Russo ◽  
Valeria B. Salinas-Ramos ◽  
Luca Cistrone ◽  
Sonia Smeraldo ◽  
Luciano Bosso ◽  
...  

Bats show responses to anthropogenic stressors linked to changes in other ecosystem components such as insects, and as K-selected mammals, exhibit fast population declines. This speciose, widespread mammal group shows an impressive trophic diversity and provides key ecosystem services. For these and other reasons, bats might act as suitable bioindicators in many environmental contexts. However, few studies have explicitly tested this potential, and in some cases, stating that bats are useful bioindicators more closely resembles a slogan to support conservation than a well-grounded piece of scientific evidence. Here, we review the available information and highlight the limitations that arise in using bats as bioindicators. Based on the limited number of studies available, the use of bats as bioindicators is highly promising and warrants further investigation in specific contexts such as river quality, urbanisation, farming practices, forestry, bioaccumulation, and climate change. Whether bats may also serve as surrogate taxa remains a controversial yet highly interesting matter. Some limitations to using bats as bioindicators include taxonomical issues, sampling problems, difficulties in associating responses with specific stressors, and geographically biased or delayed responses. Overall, we urge the scientific community to test bat responses to specific stressors in selected ecosystem types and develop research networks to explore the geographic consistency of such responses. The high cost of sampling equipment (ultrasound detectors) is being greatly reduced by technological advances, and the legal obligation to monitor bat populations already existing in many countries such as those in the EU offers an important opportunity to accomplish two objectives (conservation and bioindication) with one action.


Oryx ◽  
2021 ◽  
pp. 1-9
Author(s):  
Alegria Olmedo ◽  
Diogo Veríssimo ◽  
E.J. Milner-Gulland ◽  
Amy Hinsley ◽  
Huong Thi Thu Dao ◽  
...  

Abstract Pangolins have been exploited throughout history but evidence points to population declines across parts of their ranges since the 1960s, especially in Asia. This is the result of overexploitation for local use and international trade and trafficking of their derivatives. The prevalence of the consumption of pangolin products has been estimated for different localities in Viet Nam but, considering that national legislation prohibits the purchase of pangolin products, previous research has not accounted for the potential for biased responses. In this study, we treat pangolin consumption as a sensitive behaviour and estimate consumption prevalence of pangolin meat, scales and wine (a whole pangolin or pangolin parts or fluids soaked or mixed in rice wine) in Ho Chi Minh City using a specialized questioning method, the unmatched count technique. We also characterize the demographics of consumers. Our results suggest there is active consumption of all three pangolin products, with a best-estimate prevalence of 7% of a representative sample of Ho Chi Minh City residents for pangolin meat, 10% for scales and 6% for wine. Our prevalence estimates exceed estimates from direct questions, providing evidence for the sensitivity of pangolin consumption. We compared our analysis of consumer characteristics with existing profiles of pangolin consumers and found substantial differences, suggesting that consumption occurs among broader demographic groups than previously described. Our findings suggest that efforts to reduce demand for pangolin consumption in Viet Nam should focus on a broader range of consumers than previously identified.


2015 ◽  
Vol 23 (4) ◽  
pp. 443-460 ◽  
Author(s):  
Michael J. Lawrence ◽  
Holly L.J. Stemberger ◽  
Aaron J. Zolderdo ◽  
Daniel P. Struthers ◽  
Steven J. Cooke

War is an ever-present force that has the potential to alter the biosphere. Here we review the potential consequences of modern war and military activities on ecosystem structure and function. We focus on the effects of direct conflict, nuclear weapons, military training, and military produced contaminants. Overall, the aforementioned activities were found to have overwhelmingly negative effects on ecosystem structure and function. Dramatic habitat alteration, environmental pollution, and disturbance contributed to population declines and biodiversity losses arising from both acute and chronic effects in both terrestrial and aquatic systems. In some instances, even in the face of massive alterations to ecosystem structure, recovery was possible. Interestingly, military activity was beneficial under specific conditions, such as when an exclusion zone was generated that generally resulted in population increases and (or) population recovery; an observation noted in both terrestrial and aquatic systems. Additionally, military technological advances (e.g., GPS technology, drone technology, biotelemetry) have provided conservation scientists with novel tools for research. Because of the challenges associated with conducting research in areas with military activities (e.g., restricted access, hazardous conditions), information pertaining to military impacts on the environment are relatively scarce and are often studied years after military activities have ceased and with no knowledge of baseline conditions. Additional research would help to elucidate the environmental consequences (positive and negative) and thus reveal opportunities for mitigating negative effects while informing the development of optimal strategies for rehabilitation and recovery.


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