Generalist-specialist continuum and life history traits of Central European butterflies (Lepidoptera) - are we missing a part of the picture?

Abstract

Abstract. Analyzing life history traits of butterfly communities and faunas frequently reveals a generalist-specialist continuum as the main gradient, where species using wide arrays of resources, with good dispersal ability and fast development are distinguished from those using specialised resources, having limited dispersal ability and developing slowly. To ascertain the validity of the generalistspecialist approach for an intermediately species-rich Central European fauna, we analyzed ten life history traits for 136 species of butterflies currently occurring in the Czech Republic, using principal correspondence analysis (PCA) and controlling for phylogeny. The main gradient extracted indeed revealed a generalist-specialist continuum, while the gradient perpendicular to the main axis distinguished between small-bodied polyvoltine species feeding on small herbaceous plants and large-bodied monovoltine species feeding on grasses or woody plants. We coin "constrained voltinism continuum" for the second gradient and argue that it reflects the effect of anti-herbivore strategies of larval host plants on butterfly development. The position of the butterflies in the PCA ordination mirrors the C-S-R (Competitors -Stress tolerators -Ruderals) strategies of their host plants. Butterflies that feed on C-and R-selected plants tend to be generalists, but differ in voltinism, whereas specialists tend to feed on S-selected plants. Regressing measures of current conservation status of individual species in the Czech Republic against the two extracted life history gradients yielded a significant but weak response for the generalist-specialist continuum and no response for the constrained voltinism continuum. The weak responses were due to a wide scatter of status measures among "mid generalists". The generalist-specialist continuum is hence a rather poor predictor of species conservation status. Species of high conservation concern are found either among specialists, or among mid generalists with low to intermediate values on the constrained voltinism axis.

Ecological determinants of butterfly vulnerability across the European continent

“…Similarly, Mattila et al (2006Mattila et al ( , 2008Mattila et al ( , 2011 demonstrated that diet and habitat specificity, overwintering in larval and pupal stages and short flight period and body size predispose Lepidoptera in Finland to distribution decline. Other studies highlighted the role of hostplant growth form and life strategies in relation to butterfly development, voltinism and larval specificity (Dennis et al 2004;Cizek et al 2006Cizek et al , 2012Bartonova et al 2014). We propose that the abovementioned life-history trait component offers a suitable substitute to the widely used, but confusing specialist-generalist continuum (e.g.…”

“…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.…”

“…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 alterations in the short term are likely to filter out Lepidoptera species that display a narrow niche breadth (food and habitat), slow development and sedentary behaviour (e.g., Mattila et al 2006Mattila et al , 2011Warren et al 2001;Bartonova et al 2014;WallisDeVries 2014). Conversely, butterfly species equipped with a set of adaptive traits, including high dispersal capacity, multiple generations per year and broad trophic as well as thermal niches, have the potential to expand their range and initiate adaptive radiations (e.g., Börschig et al 2013;Ohlemüller et al 2008).…”

Urban Environments and Insect Wellbeing

“…Many, on closer investigation, prove to occur as metapopulations rather than single population units. These patterns were explored for European butterfl ies (Bartonova et al 2014 ) to reveal that the continuum was a rather poor predictor of conservation status. Species of high conservation value occurred among both specialists and mid-continuum generalists.…”

Adult longevity and its relationship with conservation status in European butterflies

“…Such a situation leads Studies conducted to date have identiied a wide range of butterly characteristics that can potentially act as proxies for extinction risk. One of the most commonly addressed aspects in this respect is the division into generalists and specialists (Nylin and Bergström 2009;Ali and Agrawal 2012;Bartoňová et al 2014). The latter group includes a disproportionally high number of threatened species due to their stricter habitat and host plant requirements (Hodgson 1993;Purvis et al 2000;Fontaine et al 2007).…”