Species richness and trait composition of butterfly assemblages change along an altitudinal gradient

Abstract

Species richness patterns along altitudinal gradients are well-documented ecological phenomena, yet very little data are available on how environmental filtering processes influence the composition and traits of butterfly assemblages at high altitudes. We have studied the diversity patterns of butterfly species at 34 sites along an altitudinal gradient ranging from 600 to 2,000 m a.s.l. in the National Park Berchtesgaden (Germany) and analysed traits of butterfly assemblages associated with dispersal capacity, reproductive strategies and developmental time from lowlands to highlands, including phylogenetic analyses. We found a linear decline in butterfly species richness along the altitudinal gradient, but the phylogenetic relatedness of the butterfly assemblages did not increase with altitude. Compared to butterfly assemblages at lower altitudes, those at higher altitudes were composed of species with larger wings (on average 9%) which laid an average of 68% more eggs. In contrast, egg maturation time in butterfly assemblages decreased by about 22% along the altitudinal gradient. Further, butterfly assemblages at higher altitudes were increasingly dominated by less widespread species. Based on our abundance data, but not on data in the literature, population density increased with altitude, suggesting a reversed density-distribution relationship, with higher population densities of habitat specialists in harsh environments. In conclusion, our data provide evidence for significant shifts in the composition of butterfly assemblages and for the dominance of different traits along the altitudinal gradient. In our study, these changes were mainly driven by environmental factors, whereas phylogenetic filtering played a minor role along the studied altitudinal range.

Ecological determinants of butterfly vulnerability across the European continent

“…In agreement, butterflies from the Iberian Peninsula and the Alps, exhibit a trait continuum with altitude, ranging from multivoltine trophic generalists with high dispersal capacity and broad climatic niches, to univoltine, trophic specialist species with restricted dispersal and narrow climatic niches (Carnicer et al 2013;Leingärtner et al 2014). …”

“…Therefore, we chose to adhere to the results without phylogenetic correction in order to cover the full set of documented species. Other studies also indicate that it is not always necessary to apply phylogenetic corrections in trait analyses (Mattila et al 2006(Mattila et al , 2011Päivinen et al 2005;Pavoine et al 2014;Bartonova et al 2014;Leingärtner et al 2014;De Bello et al 2015). This appears especially true for both this and the abovementioned studies that (partly) involve ecologically based traits, such as our climatic niche traits, which are less likely to be evolutionary conserved than morphological traits, such as body size.…”

“…Therefore, a set of life-history traits within a species is likely to be the outcome of longterm environmental selection of fitness and performance qualities for a population to persist, limited by the available phylogenetic space of individual species. Consequently, environmental gradients are often indicative for the composition of traits in species (Carnicer et al 2013;Leingärtner et al 2014). Trait-continua in various animal taxa picture arrays of specialized to more generalist species and/or from slow to fast life-styles, and are likely the result of growth versus survival trade-offs (Blackburn 1991;Wright et al 2004;Devictor et al 2008;Bielby et al 2007;Saether et al 2011;Janz and Nylin 2008), though some apparently correlated traits may actually consist of independently evolved strategies (Kraft et al 2007).…”

Environmental filtering drives herb community composition and functional trait changes across an elevational gradient

“…When environmental conditions change, dominant functional traits in the community will change as the result of species replacement and intraspecific variation (Cowles 1899). This consistency suggests that we can understand the key factors that control the composition and structure of communities by studying how plant functional traits change along complex gradients (Leingärtner et al 2014, Marteinsdóttir & Eriksson 2014, Molinari & D'Antonio 2014.…”

Butterfly phenology in Mediterranean mountains using space‐for‐time substitution

“…In this way, studies investigating how phenotypic traits change along latitudinal or elevational gradients can contribute to the prediction of species responses to climate change (de Arce Crespo & Gutiérrez, 2011;Gutiérrez & Menéndez, 1998;Hodkinson, 2005;Leingärtner, Krauss, & Steffan-Dewenter, 2014;Merrill et al, 2008). However, space-for-time substitution can become less valid at certain spatiotemporal scales (Blois, Williams, Fitzpatrick, Jackson, & Ferrier, 2013) or lead to underestimations of changes in diversity (França et al, 2016) especially under the pressure of a changing environment (Damgaard, 2019).…”