Density, climate and varying return points: an analysis of long-term population fluctuations in the threatened European tree frog

Pellet, Jérôme; Schmidt, Benedikt R.; Fivaz, Fabien; Perrin, Nicolas; Grossenbacher, Kurt

doi:10.1007/s00442-006-0432-1

Cited by 39 publications

(43 citation statements)

References 68 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This mean return rate was estimated to s a =0.303 (SD=0.097). This value is consistent with our own observations in similar CMR experiments in western Switzerland (Pellet et al 2006).…”

Section: Population-based Stochastic Simulation Model (Ramas)supporting

confidence: 83%

“…Given the above transition matrix L (3), we simulated the dynamic of a single population over 50 years. We then compared the resulting SD(k) with observed variations in the growth rate over 20 years in an isolated population near Lerchenfeld (Pellet et al 2006). Standard deviation on the mean growth rate was estimated as SD(k RAMAS )= 0.860, while the observed value was SD(k obs )=0.668, thus suggesting that our transition matrix provided a reasonably good approximation of environmental stochasticity.…”

Section: Population-based Stochastic Simulation Model (Ramas)mentioning

confidence: 99%

“…Evidence of density-dependent regulation has been highlighted in an analysis of long-term tree frog population dynamics (Pellet et al 2006). We thus included a Ricker-type (linear or scramble) density dependence function for each population, assuming that density dependence affected both fecundity and survival.…”

Section: Population-based Stochastic Simulation Model (Ramas)mentioning

confidence: 99%

See 2 more Smart Citations

The contribution of patch topology and demographic parameters to population viability analysis predictions: the case of the European tree frog

2006

Self Cite

View full text Add to dashboard Cite

Population viability analyses (PVA) are increasingly used in metapopulation conservation plans. Two major types of models are commonly used to assess vulnerability and to rank management options: population-based stochastic simulation models (PSM such as RAMAS or VORTEX) and stochastic patch occupancy models (SPOM). While the first set of models relies on explicit intrapatch dynamics and interpatch dispersal to predict population levels in space and time, the latter is based on spatially explicit metapopulation theory where the probability of patch occupation is predicted given the patch area and isolation (patch topology). We applied both approaches to a European tree frog (Hyla arborea) metapopulation in western Switzerland in order to evaluate the concordances of both models and their applications to conservation. Although some quantitative discrepancies appeared in terms of network occupancy and equilibrium population size, the two approaches were largely concordant regarding the ranking of patch values and sensitivities to parameters, which is encouraging given the differences in the underlying paradigms and input data.

show abstract

“…This mean return rate was estimated to s a =0.303 (SD=0.097). This value is consistent with our own observations in similar CMR experiments in western Switzerland (Pellet et al 2006).…”

Section: Population-based Stochastic Simulation Model (Ramas)supporting

confidence: 83%

Section: Population-based Stochastic Simulation Model (Ramas)mentioning

confidence: 99%

Section: Population-based Stochastic Simulation Model (Ramas)mentioning

confidence: 99%

See 1 more Smart Citation

The contribution of patch topology and demographic parameters to population viability analysis predictions: the case of the European tree frog

2006

Self Cite

View full text Add to dashboard Cite

show abstract

“…Put simply, in a growing population, early maturity is favored whereas delayed maturity is favored in shrinking populations (Stearns 1992). Amphibian populations are notorious for strong fluctuations in size (Semlitsch et al 1996, Meyer et al 1998, Pellet et al 2006. In years when the population is about to grow, early metamorphosis at a small size may be favored because it leads to early maturity.…”

Section: Fig 3 Integrative Measures Of Juvenile Performance (A)mentioning

confidence: 99%

From metamorphosis to maturity in complex life cycles: equal performance of different juvenile life history pathways

Schmidt

Hödl

Schaub

2012

Ecology

Self Cite

View full text Add to dashboard Cite

Performance in one stage of a complex life cycle may affect performance in the subsequent stage. Animals that start a new stage at a smaller size than conspecifics may either always remain smaller or they may be able to "catch up" through plasticity, usually elevated growth rates. We study how size at and date of metamorphosis affected subsequent performance in the terrestrial juvenile stage and lifetime fitness of spadefoot toads (Pelobates fuscus). We analyzed capture-recapture data of >3000 individuals sampled during nine years with mark-recapture models to estimate first-year juvenile survival probabilities and age-specific first-time breeding probabilities of toads, followed by model selection to assess whether these probabilities were correlated with size at and date of metamorphosis. Males attained maturity after two years, whereas females reached maturity 2-4 years after metamorphosis. Age at maturity was weakly correlated with metamorphic traits. In both sexes, first-year juvenile survival depended positively on date of metamorphosis and, in males, also negatively on size at metamorphosis. In males, toads that metamorphosed early at a small size had the highest probability to reach maturity. However, because very few toadlets metamorphosed early, the vast majority of male metamorphs had a very similar probability to reach maturity. A matrix projection model constructed for females showed that different juvenile life history pathways resulted in similar lifetime fitness. We found that the effects of date of and size at metamorphosis on different juvenile traits cancelled each other out such that toads that were small or large at metamorphosis had equal performance. Because the costs and benefits of juvenile life history pathways may also depend on population fluctuations, ample phenotypic variation in life history traits may be maintained. Abstract. Performance in one stage of a complex life cycle may affect performance in the subsequent stage. Animals that start a new stage at a smaller size than conspecifics may either always remain smaller or they may be able to ''catch up'' through plasticity, usually elevated growth rates. We study how size at and date of metamorphosis affected subsequent performance in the terrestrial juvenile stage and lifetime fitness of spadefoot toads (Pelobates fuscus). We analyzed capture-recapture data of .3000 individuals sampled during nine years with mark-recapture models to estimate first-year juvenile survival probabilities and agespecific first-time breeding probabilities of toads, followed by model selection to assess whether these probabilities were correlated with size at and date of metamorphosis. Males attained maturity after two years, whereas females reached maturity 2-4 years after metamorphosis. Age at maturity was weakly correlated with metamorphic traits. In both sexes, first-year juvenile survival depended positively on date of metamorphosis and, in males, also negatively on size at metamorphosis. In males, toads that metamorphosed early at a sma...

show abstract

“…The assumption that population growth rate decreases when population density increases seems reasonable for most organisms. However, the impact of intraspecific competition on wild populations may be masked by a set of important density-independent factors, including climate change and habitat perturbations (Saether et al 1999, Sanders and Gordon 2004, Pellet et al 2006. A negative feedback between population density and population growth rate can derive from two nonexclusive phenomena.…”

Section: Introductionmentioning

confidence: 99%

Intraspecific competition affects population size and resource allocation in an ant dispersing by colony fission

Boulay

Galarza

Chéron

et al. 2010

Ecology

View full text Add to dashboard Cite

Abstract. Intraspecific competition is a pervasive phenomenon with important ecological and evolutionary consequences, yet its effect in natural populations remains controversial. Although numerous studies suggest that in many cases populations across all organisms are limited by density-dependent processes, this conclusion often relies on correlative data. Here, using an experimental approach, we examined the effect of intraspecific competition on population regulation of the ant Aphaenogaster senilis. In this species females are philopatric while males disperse by flying over relatively long distances. All colonies were removed from 15 experimental plots, except for one focal colony in each plot, while 15 other plots remained unmanipulated. After the first reproductive season, nest density in the experimental plots returned to a level nonsignificantly different from that in the control plots, which was not expected if the populations were indeed regulated by density-independent phenomena. In both the control plots and the experimental plots colonies remained overdispersed throughout the experiment, suggesting colony mutual exclusion. Nests outside the plots rapidly extended their foraging span, but we did not detect any significant inward migration into the experimental plots. Experimental reduction in density did not significantly affect the focal colonies' biomass, measured just before the first reproductive season. However, the ratio of males to workers-pupae biomasses was smaller in experimental plots, suggesting that colonies there had redirected part of the resources normally allocated to male production to the production instead of new workers. Microsatellite analysis indicated that, after the reproductive season, many colonies in the experimental plots were headed by a young queen that was the mother of the brood but not of the old workers, indicating that reduction in colony density stimulated fission of the remaining colonies. Finally, at the end of the experiment, 14 months after experimental reduction in density, colonies that derived from fission were smaller in the experimental than in the control plots, suggesting that the former had undergone fission at a smaller size than in control plots, which presumably allowed them to colonize the emptied areas. We conclude that colonies adjust resource allocation and colony fission to the degree of intraspecific competition.

show abstract

Density, climate and varying return points: an analysis of long-term population fluctuations in the threatened European tree frog

Cited by 39 publications

References 68 publications

The contribution of patch topology and demographic parameters to population viability analysis predictions: the case of the European tree frog

The contribution of patch topology and demographic parameters to population viability analysis predictions: the case of the European tree frog

From metamorphosis to maturity in complex life cycles: equal performance of different juvenile life history pathways

Intraspecific competition affects population size and resource allocation in an ant dispersing by colony fission

Contact Info

Product

Resources

About