Drivers of amphibian population dynamics and asynchrony at local and regional scales

Abstract

1. Identifying the drivers of population fluctuations in spatially distinct populations remains a significant challenge for ecologists. Whereas regional climatic factors may generate population synchrony (i.e. the Moran effect), local factors including the level of density dependence may reduce the level of synchrony. Although divergences in the scaling of population synchrony and spatial environmental variation have been observed, the regulatory factors that underlie such mismatches are poorly understood. Few previous studies have investigated how density-dependent processes andpopulation-specific responses to weather variation influence spatial synchrony at both local and regional scales. We addressed this issue in a pond-breeding amphibian, the great crested newt Triturus cristatus. We used capture-recapture data collected through long-term surveys in five T. cristatus populations in Western Europe.3. In all populations-and subpopulations within metapopulations-population size, annual survival and recruitment fluctuated over time. Likewise, there was considerable variation in these demographic rates between populations and within metapopulations. These fluctuations and variations appear to be context-dependent and more related to site-specific characteristics than local or regional climatic drivers.We found a low level of demographic synchrony at both local and regional levels.Weather has weak and spatially variable effects on survival, recruitment and population growth rate. In contrast, density dependence was a common phenomenon (at least for population growth) in almost all populations and subpopulations. 4. Our findings support the idea that the Moran effect is low in species where the population dynamics more closely depends on local factors (e.g. population density and habitat characteristics) than on large-scale environmental fluctuation (e.g. regional climatic variation). Such responses may have far-reaching consequences for the long-term viability of spatially structured populations and their ability to respond to large-scale climatic anomalies.

Drivers and spatial patterns of population synchrony of fish species in a floodplain

“…Spatial variation in density dependence is also known to decrease the effect of environmental stochasticity on population synchrony (Cayuela et al., 2020; Hugueny, 2006; Liebhold et al., 2006; Peltonen et al., 2002). For example, Peltonen et al.…”

“…We did not find any relationship between synchrony of A. lacustris and of its most consumed prey species, which may favor the hypothesis of a shared environmental effect. Spatial variation in density dependence is also known to decrease the effect of environmental stochasticity on population synchrony (Cayuela et al, 2020;Hugueny, 2006;Liebhold et al, 2006;Peltonen et al, 2002). For example, Peltonen et al (2002) found that the mismatch between population synchrony and environmental synchrony in gypsy moth (in terms of their distance decays) could be attributed to geographic differences in density dependence among local populations.…”

“…For example, habitat heterogeneity and biotic interactions can cause spatial variation in density dependence structures (Agrawal et al., 2004; Liebhold et al., 2006; Roy et al., 2016; Stenseth et al., 1999). This variation, in turn, decreases the influence of the Moran effect (i.e., of density‐independent factors) and dispersal on spatial synchrony (Anderson, Sheppard, et al., 2018; Cayuela et al., 2020; Hugueny, 2006; Liebhold et al., 2006; Peltonen et al., 2002; Royama, 1992; Walter et al., 2017).…”

An abnormally early hibernation ending of the Red-bellied toad (Bombina bombina) (Discoglossidae, Anura) in the populations of the Medveditsa river valley (Saratov region)

“…Бесхвостые амфибии относятся к холоднокровным позвоночным и поэтому наиболее чувствительны к климатическим изменениям (Маслова, 2006;Beebee, 1995;Grant et al, 2020;Green et al, 2020). Глобальное потепление сопровождается значимой трансформацией локальных погодно-климатических условий, которые оказывают влияние на факторы, существенные для популяций амфибий (Cayuela et al, 2020). К наиболее важным явлениям, очевидно, следует отнести фенологические сдвиги репродукции, а также изменение водности нерестовых водоёмов, иногда приводящие к их полной деградации (Ермохин, Табачишин, 2018 а;Yermokhin et al, 2017.…”

Drought effects on invertebrate metapopulation dynamics and quasi‐extinction risk in an intermittent river network

“…Population‐level responses to large‐scale disturbance and stress can be spatially heterogeneous if local habitat conditions or connectivity vary across a landscape (Patrick et al, 2021). In such cases, large‐scale environmental controls may be locally attenuated or exacerbated, allowing for a diversity of biological responses depending on local conditions (Bunnell et al, 2010; Cayuela et al, 2020; Hansen et al, 2019). Such diverse responses are key to preserving asynchronous dynamics and ecological rescue, that is, the capacity of colonists from thriving populations to repopulate impacted ones through dispersal (Brown & Kodric‐Brown, 1977; Hammond et al, 2020).…”