Modelling the population viability of a threatened amphibian with a fast life-history

2015 ◽  
Vol 26 (1) ◽  
pp. 9-19 ◽  
Author(s):  
Evan J. Pickett ◽  
Michelle P. Stockwell ◽  
John Clulow ◽  
Michael J. Mahony
Keyword(s):  
Life History ◽  
Population Viability

Evidence of long and discontinuous juvenile periods in Trillium catesbaei under contrasting levels of herbivory

Botany ◽  
2014 ◽  
Vol 92 (1) ◽  
pp. 77-81 ◽  
Author(s):  
Christopher R. Webster ◽  
Michael A. Jenkins
Keyword(s):  
Life History ◽  
Reproductive Success ◽  
Age Structure ◽  
Morphological Characteristics ◽  
Population Viability ◽  
Plant Age ◽  
Life History Stage ◽  
Structure And Morphology ◽  
Single Leaf ◽  
Poor Indicator

We investigated the influence of chronic herbivory by white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)) on the age structure and morphology of Trillium catesbaei Elliott. At sites with contrasting histories of deer abundance (Cades Cove, high; Whiteoak Sink, low), we measured morphological characteristics and determined minimum plant age for 60 plants (30 per site) in the single-leaf life-history stage. We chose this stage because its presence is considered an indication of successful reproduction by the previous generation, but its value could be inflated if plants regress or remain in this stage for extended periods. Our results suggest that T. catesbaei may spend upwards of a decade in this stage. Cades Cove single leaves were significantly older (p = 0.011) than those at Whiteoak Sink. Rhizome recession (decay of the oldest portion) was more common at Cades Cove, suggesting greater regression to this stage from three-leaf stages. Although minimum plant age was significantly associated with vegetative attributes (p < 0.002) at Whiteoak Sink, these attributes were decoupled at Cades Cove (p ≥ 0.642). Collectively, our results suggest that chronic herbivory may lead to a long and regressive residency period in the single-leaf stage. Consequently, in Trillium populations heavily impacted by deer, the number of single-leaf plants may be a poor indicator of reproductive success and population viability.

Aggregation Status and Cue Type Modify Tadpole Response to Chemical Cues

2014 ◽  
Vol 6 (1) ◽  
pp. 199-207 ◽  
Author(s):  
Devin B. Preston ◽  
M. R. J. Forstner
Keyword(s):  
Life History ◽  
Chemical Cues ◽  
Response Strength ◽  
Population Viability ◽  
Antipredator Response ◽  
History Effects ◽  
Honestly Significant Difference ◽  
Significant Difference ◽  
History Of ◽  
Reduced Activity

Abstract Many anuran larvae exhibit an antipredator response to chemical cues released by potential predators. The genus Bufo is no exception, as many bufonids exhibit an antipredator response (e.g., reduction in activity) to the presence (recent and current) of predators. Using a mesocosm experiment in a field laboratory setting, we tested solo and groups of Bufo (Incilius) nebulifer tadpoles for an antipredator response to chemical cues produced by 1) the presence of anisopteran nymphs (kairomone cue) and 2) the predation of conspecifics by anisopteran nymphs (a combination of diet and alarm cues, which we termed predation cue). We quantified the magnitude of the response by calculating response strength. We analyzed data with a blocked ANOVA followed by a Tukey's honestly significant difference analysis. We found that chemical cue type (kairomone vs. predation) affected response strength, but aggregation status (solo vs. group) did not. Furthermore, solo tadpoles and groups of tadpoles reduced their activity in response to predation cues, whereas only solo tadpoles reduced their activity in response to kairomone cues, a heretofore unobserved phenomenon. Our results suggest that B. nebulifer tadpoles modulate their response to specific types of chemical cues depending on their aggregation status. As reduced activity comes at a cost to resource acquisition and growth, aggregation status may indirectly affect the life history of B. nebulifer. The elucidation of these potential life history effects may aid managers in estimating anuran population viability.

Sex and sociality in a disconnected world: a review of the impacts of habitat fragmentation on animal social interactionsThis review is one of a series dealing with some aspects of the impact of habitat fragmentation on animals and plants. This series is one of several virtual symposia focussing on ecological topics that will be published in the Journal from time to time.

2007 ◽  
Vol 85 (10) ◽  
pp. 1065-1079 ◽  
Author(s):  
Sam C. Banks ◽  
Maxine P. Piggott ◽  
Adam J. Stow ◽  
Andrea C. Taylor
Keyword(s):  
Life History ◽  
Habitat Fragmentation ◽  
Social Interactions ◽  
Spatial Configuration ◽  
Interspecific Interactions ◽  
Population Viability ◽  
Life History Strategies ◽  
Future Research ◽  
Extensive Literature ◽  
The Impact

Despite the extensive literature describing the impacts of habitat fragmentation on the distribution and abundance of species, fragmentation effects on life-history strategies have been relatively understudied. Social interactions are important life-history attributes that have fitness consequences for individuals and have been observed to differ among populations in relation to geographic and demographic variability. Therefore, habitat fragmentation is expected to affect social interactions, and these social impacts or responses may contribute to population viability and broad-scale patterns of distribution and abundance in fragmented landscapes. Here we review the emerging literature on this issue. We focus on the impacts of habitat fragmentation that are expected to, or have been observed to, affect social strategies. These include altered resource distribution (e.g., habitat quality, spatial configuration of patches), interspecific interactions (e.g., predator–prey and host–parasite dynamics, human disturbance), and sex (mate availability and inbreeding risk). The studies we cite identified altered social interactions in response to these influences, including changes to home-range overlap, territoriality, group size, and mating systems. The observed changes to social interactions include passive responses, whereby social interactions are affected by constraints introduced by habitat fragmentation, and adaptive social responses to a modified environment. We suggest that future research could focus on individual fitness benefits and on consequences for population viability of altered social interactions in fragmented environments.

scholarly journals Recent demographic histories and genetic diversity across pinnipeds are shaped by anthropogenic interactions and mediated by ecology and life-history

2018 ◽  
Author(s):  
M.A. Stoffel ◽  
E. Humble ◽  
K. Acevedo-Whitehouse ◽  
B.L. Chilvers ◽  
B. Dickerson ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Life History ◽  
Large Scale ◽  
Biodiversity Loss ◽  
Single Species ◽  
Population Viability ◽  
Breeding Habitat ◽  
Comparative Approach ◽  
Population Declines ◽  
Effective Population

AbstractA central paradigm in conservation biology is that population bottlenecks reduce genetic diversity and negatively impact population viability and adaptive potential. In an era of unprecedented biodiversity loss and climate change, understanding both the determinants and consequences of bottlenecks in wild populations is therefore an increasingly important challenge. However, as most studies have focused on single species, the multitude of potential drivers and the consequences of bottlenecks remain elusive. Here, we used a comparative approach by integrating genetic data from over 11,000 individuals of 30 pinniped species with demographic, ecological and life history data to elucidate the consequences of large-scale commercial exploitation by 18th and 19th century sealers. We show that around one third of these species exhibit strong genetic signatures of recent population declines, with estimated bottleneck effective population sizes reflecting just a few tens of surviving individuals in the most extreme cases. Bottleneck strength was strongly associated with both breeding habitat and mating system variation, and together with global abundance explained a large proportion of the variation in genetic diversity across species. Overall, there was no relationship between bottleneck intensity and IUCN status, although three of the four most heavily bottlenecked species are currently endangered. Our study reveals an unforeseen interplay between anthropogenic exploitation, ecology, life history and demographic declines, sheds new light on the determinants of genetic diversity, and is consistent with the notion that both genetic and demographic factors influence population viability.

The persistence niche: what makes it and what breaks it for two fire-prone plant species

2007 ◽  
Vol 55 (3) ◽  
pp. 273 ◽  
Author(s):  
David A. Keith ◽  
Mark G. Tozer ◽  
Tracey J. Regan ◽  
Helen M. Regan
Keyword(s):  
Life History ◽  
Seed Production ◽  
Life Histories ◽  
Phytophthora Cinnamomi ◽  
Population Viability ◽  
Vital Rates ◽  
High Fecundity ◽  
In Fire ◽  
Rates Of Growth ◽  
Regeneration Niches

Persistence niches are expected to favour qualitatively different plant life histories compared with regeneration niches. In fire-prone habitats, for example, resprouting plants may be expected to exploit persistence niches, whereas obligate-seeders by definition exploit regeneration niches. Resprouter life histories should be typified by high rates of survival, which may be offset by relatively low rates of growth and reproduction. This combination of characters is expected to result from trade-offs in resource allocation and because the longevity of individual plants should buffer their populations against the effects of recruitment failure. We asked whether two resprouting perennial shrubs, Epacris barbata Melville and Xanthorrhoea resinifera (Sol. Ex Kite) E.C.Nelson & D.J.Bedford, exhibited the life-history character combinations that are expected for species exploiting a persistence niche. We also investigated how a change in habitat suitability caused by the invasion of a root pathogen may limit the ability of these species to occupy persistence niches. Demographic censuses of several years’ duration in two populations of each species yielded estimates of vital rates that were consistent with the life-history profile expected for a persistence niche. Rates of background survival were high and rates of fire-related mortality were low in both species. As expected, these were associated with low rates of growth and seedling establishment, although rates of seed production and viability were relatively high in both species. The importance of survival was confirmed by stochastic population models, which showed that population viability was more sensitive to decreases in survival of mature plants and increases in fire mortality of established plants than to changes in other vital rates. Seedling growth rates were also relatively important in E. barbata. Populations of both species that had been infected by root rot disease, Phytophthora cinnamomi, had substantially reduced survival rates and, consequently, reduced population viability. These effects were more extreme in E. barbata than in X. resinifera. We conclude that processes that reduce survival, such as disease infection and habitat loss, rather than processes that impede seed production and recruitment mediate the persistence niche. However, we discuss the possibility that this dependency might be mitigated by high fecundity if infrequent conditions that permit large recruitment events have so far eluded detection.

scholarly journals Life history mediates mate limitation and population viability in self‐incompatible plant species

2014 ◽  
Vol 4 (6) ◽  
pp. 673-687 ◽  
Author(s):  
Peter H. Thrall ◽  
Francisco Encinas‐Viso ◽  
Susan E. Hoebee ◽  
Andrew G. Young
Keyword(s):  
Life History ◽  
Plant Species ◽  
Population Viability ◽  
Mate Limitation

scholarly journals Population viability analysis and potential of its application to Danube sturgeons

2009 ◽  
Vol 61 (1) ◽  
pp. 123-128 ◽  
Author(s):  
I. Jaric ◽  
Mirjana Lenhardt ◽  
G. Cvijanovic ◽  
T. Ebenhard
Keyword(s):  
Life History ◽  
River Basin ◽  
Habitat Loss ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Danube River ◽  
The Danube River ◽  
Viability Analysis ◽  
Sturgeon Species ◽  
Danube River Basin

Sturgeon species in the Danube River basin have experienced severe decline. Besides overexploitation, habitat loss, and pollution, they are further endangered by lack of efficient policy and management, as well as by serious lack of knowledge about their life history. Although population viability analysis (PVA) could represent an extremely valuable tool to cope with these problems, it has not so far been applied to Danube populations. This paper represents an assess?ment of different PVA methods and models developed for sturgeon species. It analyzes their results, main advantages, drawbacks, and problems, and discusses the possibility of applying PVA to sturgeon populations in the Danube River basin.

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