Movements and occurrence in two closely related fritillary species

Abstract

Mobility may affect species' distribution patterns in heterogeneous landscapes, and it might impact fitness by influencing mating success, predation avoidance, and foraging success. Here, we studied causes and consequences of mobility patterns in butterflies: Argynnis adippe, a specialist constrained to warm microhabitats within woodland landscapes, and A. aglaja, a relative generalist that also inhabits grasslands, and tolerates lower temperatures. We explored associations of movement and occurrence patterns, population size and density, niche breadth, wing size, and different types of behaviour prior to capture by conducting a mark‐release‐recapture study on the Swedish island Öland. We marked 1 935 A. aglaja and 123 A. adippe and achieved recapture rates of 9.5% (A. aglaja), and 8.9% (A. adippe). Estimated population densities were 5 066 and 814 individuals per km2, for A. aglaja and A. adippe, respectively. Argynnis aglaja was less likely to perform long‐distance flights according to estimated dispersal kernels, hinting at negative density‐dependent dispersal in these species. Although we detected the longest flight distances ever in these species in MRR studies (11.9 km for A. aglaja and 3.7 km for A. adippe), most butterflies were recaptured within 200 meters (60–80%). Low recapture rates along with low estimated residence times and the potential for long movement might indicate that many individuals left the study area, and that the species form open populations, stretching over large areas. Despite significant differences in wing size and behaviour types, mean observed flight distances were similar in these species.

Linking large‐scale genetic structure of three Argynnini butterfly species to geography and environment

“…In S. aglaja , northern and southern Iberian samples differed substantially from each other, possibly enforced by the Baetic and Sierra Morena Mountain Ranges, while such a structuring was not observed in F. adippe . As F. adippe seems to more likely perform long‐distance dispersal than S. aglaja (Polic et al, 2020), there might have been more exchange between northern and southern Iberian populations in F. adippe than in S. aglaja , resulting in the slight differences in the contemporary genetic structure in these species. Differences in dispersal capacity have been shown to affect spatial genetic patterns in other taxa as well, with an increased genetic structure in organisms of limited mobility as opposed to highly mobile species, such as in grasshoppers (Ortego et al, 2021) and songbirds (Cros et al, 2020).…”

“…Speyeria aglaja is distributed from Northern Africa over Europe and Russia to Southeast Asia, reaching as far north as Southern Lapland, whereas F. adippe 's northern distribution only extends to central Sweden (Fox et al, 2011; Franzén & Johannesson, 2007; Tolman & Lewington, 2012; Warren, 1995), and F. niobe only reaches southern Sweden (Eliasson et al, 2005; Reinhardt & Bolz, 2011; van Swaay & Warren, 1999). Further, these species differ in their degree of ecological generalism, dispersal abilities, habitat preferences and host plant use (Eliasson et al, 2005; Forster & Wohlfahrt, 1955; Fric et al, 2005; Higgins & Riley, 1970; Komonen et al, 2004; Öckinger et al, 2006; Polic et al, 2020; Pollard & Yates, 1994; Zima et al, 2013). Speyeria aglaja is a widespread and rather common species that occupies a wide range of habitats and can breed at lower temperatures than the other two fritillaries (Ellis et al, 2010; Zimmermann et al, 2009).…”

“…While the larvae of F. adippe and F. niobe only feed on Viola species, S. aglaja larvae have also been found foraging on Bistorta major and Persicaria spp., depending on their geographical location (Forster & Wohlfahrt, 1955; Fric et al, 2005; Higgins & Riley, 1970; Tolman & Lewington, 2012). According to their dispersal ability and to rankings based on “mobility indices” as assessed by butterfly experts, all three species are considered as intermediately mobile (Komonen et al, 2004; Öckinger et al, 2006; Pollard & Yates, 1994; Zima et al, 2013), although F. adippe has been reported to be more likely to engage in long‐distance dispersal of several kilometres than S. aglaja (Polic et al, 2020). These interspecific divergences could lead to different large‐scale genetic patterns among the species, despite them being phylogenetically close and exposed to similar environmental conditions and selection regimes.…”

Perishing rich, expanding poor: Demography and population genetic patterns in two congeneric butterflies

“…Studying them by traditional quantitative field methods, such as transect counts or mark–recapture, requires more effort than for high‐density specialists, and the same applies for acquiring sufficiently abundant samples for population genetic studies. So far, only a few studies have overcome these obstacles (field studies: Kadlec et al, 2010; Marschalek, 2020; Mccullough et al, 2021; Polic et al, 2021; genetics, e.g., Hill et al, 2018; see also Text S1). Consequently, little is known regarding the population structures of moderate specialists.…”

“…The genus itself (Tuzov, 2003) includes 22 Eurasian species, plus an additional 14 American species traditionally classified as Speyeria Scudder, 1872 (paraphyletic with Argynnis : Simonsen et al, 2006; De Moya et al, 2017; Sims, 2017). Their generalist traits include moderate to large wingspan, strong flight and relatively low population densities (Polic et al, 2021; Zimmermann et al, 2009). The traits pointing towards specialism include a single adult generation per year, narrow host plant ranges and narrow requirements for host plant conditions (Ellis et al, 2019; Salz & Fartmann, 2009, 2017; Spitzer, Beneš, & Konvička, 2009; Warren, 1995).…”