Low winter precipitation, but not warm autumns and springs, threatens mountain butterflies in middle-high mountains

Abstract

Low-elevation mountains represent unique model systems to study species endangered by climate warming, such as subalpine and alpine species of butterflies. We aimed to test the effect of climate variables experienced by Erebia butterflies during their development on adult abundances and phenology, targeting the key climate factors determining the population dynamics of mountain insects. We analysed data from a long-term monitoring of adults of two subalpine and alpine butterfly species, Erebia epiphron and E. sudetica (Nymphalidae: Satyrinae) in the Jeseník Mts and Krkonoše Mts (Czech Republic). Our data revealed consistent patterns in their responses to climatic conditions. Lower precipitation (i.e., less snow cover) experienced by overwintering larvae decreases subsequent adult abundances. Conversely, warmer autumns and warmer and drier springs during the active larval phase increase adult abundances and lead to earlier onset and extended duration of the flight season. The population trends of these mountain butterflies are stable or even increasing. On the background of generally increasing temperatures within the mountain ranges, population stability indicates dynamic equilibrium of positive and detrimental consequences of climate warming among different life history stages. These contradictory effects warn against simplistic predictions of climate change consequences on mountain species based only on predicted increases in average temperature. Microclimate variability may facilitate the survival of mountain insect populations, however the availability of suitable habitats will strongly depend on the management of mountain grasslands.

Climatic niche conservatism and ecological diversification in the Holarctic cold-dwelling butterfly genusErebia

“…In addition, different Erebia species seem to have diversified in their adult phenologies, which might have further created niche partitioning (van Dam et al 2019). Further, conditions undetected by our study, such as winter temperature minima or low snow cover (Konvicka et al 2021), may affect more vulnerable stages of developmental cycle such as overwintering larvae (Vrba et al 2017).…”

“…In addition, different Erebia species seem to have diversified in their adult phenologies, which might have further created niche partitioning (van Dam et al 2019). Further, conditions undetected by our study, such as winter temperature minima or low snow cover (Konvicka et al 2021), may affect more vulnerable stages of developmental cycle such as overwintering larvae (Vrba et al 2017). Tables Table 1. Tests of phylogenetic signal in climatic variables and elevation in the butterfly genus Erebia for the consensus tree and for 1,000 trees randomly drawn from the posterior distribution (mean value and 95% confidence interval).…”

Not Too Warm, Not Too Cold: Thermal Treatments to Slightly Warmer or Colder Conditions from Mother’s Origin Can Enhance Performance of Montane Butterfly Larvae

“…In the context of shrinking body sizes in ectotherms [ 61 ] and the higher impact of global warming on mountain ecosystems [ 62 ], ideally, more mechanistic studies, such as this one, need to be conducted on different life history stages to glean a better understanding of factors controlling for mature size shifts. The inclusion of the second overwintering stage of semivoltine species in long-term studies will be challenging but is urgently needed to shed light on how the shifting snow cover regimen can alter mass and overwintering metabolism on such species (see Konvička et al [ 13 ]). Another important aspect for larval development and survival rate of the immature stages of these stenotopic butterflies would be the inclusion of specific microclimatic conditions [ 63 ].…”

“…Furthermore, diapause termination of alpine caterpillars is often influenced by snowmelt, and the advanced flight of the alpine butterfly, Erebia epiphron , was attributable to shorter winters or to earlier snowmelts [ 12 ]. Shortened periods of snow cover may even cause mortality, as the buffer layer of snow under which insect larvae spend the winter in diapause decreases [ 13 ].…”

Variation in Plant–Pollinator Network Structure along the Elevational Gradient of the San Francisco Peaks, Arizona

“…Further, pollinators in montane environments may be especially susceptible to changing climate; competition between pollinators may become more prevalent with increased elevation if the range expansion of lower elevation pollinators encroaches on the space typically reserved for the higher-elevation pollinator groups, such as bumblebees, non-syrphid flies, or cold-adapted butterflies [4,81]. These higher-elevation insect pollinators often have narrow niches restricted to upper altitudes with cooler temperatures and low seasonal temperature variation [81][82][83]. Unfortunately, areas supporting these conditions are expected to shrink disproportionately under future climate scenarios [84], potentially causing certain pollinator taxa to reduce their ranges to remain within optimal habitat [81,85].…”