Range expansion, habitat use, and choosiness in a butterfly under climate change: Marginality and tolerance of oviposition site selection

Abstract

Poleward range shifts under climate change involve the colonization of new sites and hence the foundation of new populations at the expanding edge. We studied oviposition site selection in a butterfly under range expansion (Lycaena dispar), a key process for the establishment of new populations. We described and compared the microhabitats used by the species for egg laying with those available across the study sites both in edge and in core populations. We carried out an ecological niche factor analysis (ENFA) to estimate (1) the variety of microhabitats used by the butterfly for egg laying (tolerance) and (2) the extent to which these selected microhabitats deviated from those available (marginality). Microhabitat availability was similar in edge and core populations. Ambient temperature recorded at the site level above the vegetation was on average lower at core populations. In contrast with what is often assumed, edge populations did not have narrower microhabitat use compared to core populations. Females in edge populations even showed a higher degree of generalism: They laid eggs under a wider range of microhabitats. We suggest that this pattern could be related to an overrepresentation of fast deciding personalities in edge populations. We also showed that the thermal time window for active female behavior was reduced in edge populations, which could significantly decrease the time budget for oviposition and decrease the threshold of acceptance during microhabitat selection for oviposition in recently established populations.

On the macroecological significance of eco-evolutionary dynamics: the range shift–niche breadth hypothesis

“…For instance, latitudinal biodiversity gradients imply that dense, tropical communities may house more extreme resource specialists than can simpler, high-latitude communities, whereas potentially lower interspecific competition due to fewer species at higher latitudes may favour increased generalism [17,19]. In addition, shorter growing seasons might select for more relaxed discrimination rules, and thus broader resource or habitat niches at high latitudes, as longer search times become increasingly costly [45]. Increasingly broad diets or habitat requirements selected at high latitudes may, like broad climate niches, also facilitate range expansion [46,47], as biotic niche limits on species’ ranges are certainly well described [48].…”

“…Thus, niche breadth may evolve under purely spatial, dispersal-promoting processes at range expansion fronts irrespective of whether it also improves adaptation to novel conditions. Subsequent empirical work has provided additional supportive evidence that ‘fast deciding’ individuals dominate recently colonized populations [45].…”

“…Additional data and synthesis work are needed to refine predictions and outcomes under each of the major hypotheses, and to determine the relative prevalence of each mechanism overall. Such studies may, for instance, compare macroecological patterns between range-expanding and stable-ranged species [25,33], employ theoretical or experimental approaches to distinguish alternative mechanisms [6,61,62,69] or evaluate the (changing) role of different microevolutionary forces on niche breadth, across species’ range expansion gradients [31,45,51,56]. Many of the available empirical studies of niche macroecology involve ectothermic species, with a historically strong focus on terrestrial insects, and typically only a single niche dimension is considered at a time.…”

The importance of eco-evolutionary dynamics for predicting and managing insect range shifts

“…Neutral, rather than adaptive processes, can dominate evolutionary changes during colonization events, making it difficult to predict range shift outcomes. Nonetheless, certain anticipatory responses may also evolve, for example, serial colonization at the leading edge of range shifts can select for indiscriminate individuals that are more likely to accept marginal habitat conditions [26].…”

Integrating learning into animal range dynamics under rapid human‐induced environmental change

“…However, ecological opportunity may not guarantee successful establishment if the novel resources are not innately recognized. In organisms that are under time stress, as are many short-living ectotherms (Doak et al, 2006;Martin et al, 2021), an individual will particularly benefit from the ability to identify and exploit a novel resource. Let us consider the example of a dispersing butterfly that arrives in an unfamiliar environment.…”