Cross-continental phylogeography of two Holarctic Nymphalid butterflies, Boloria eunomia and Boloria selene

Abstract

Pleistocene glaciations had significant effects on the distribution and evolution of species inhabiting the Holarctic region. Phylogeographic studies concerning the entire region are still rare. Here, we compared global phylogeographic patterns of one boreo-montane and one boreo-temperate butterflies with largely overlapping distribution ranges across the Northern Hemisphere, but with different levels of range fragmentation and food specialization. We reconstructed the global phylogeographic history of the boreo-montane specialist Boloria eunomia (n = 223) and of the boreo-temperate generalist Boloria selene (n = 106) based on mitochondrial and nuclear DNA markers, and with species distribution modelling (SDM). According to the genetic structures obtained, both species show a Siberian origin and considerable split among populations from Nearctic and Palaearctic regions. According to SDMs and molecular data, both butterflies could inhabit vast areas during the moderate glacials. In the case of B. selene, high haplotype diversity and low geographic structure suggest long-lasting interconnected gene flow among populations. A stronger geographic structuring between populations was identified in the specialist B. eunomia, presumably due to the less widespread, heterogeneously distributed food resources, associated with cooler and more humid climatic conditions. Populations of both species show opposite patterns across major parts of North America and in the case of B. eunomia also across Asia. Our data underline the relevance to cover entire distribution ranges to reconstruct the correct phylogeographic history of species.

Asymmetry in host plant preferences of two ecotypes of Boloria eunomia (Lepidoptera: Nymphalidae)

“…This ecotype, unlike the meadow ecotype, showed no signifi cant preference for the four plants (three Ericaceae species and P. bistorta) provided. Phylogeographic studies indicate that the bog fritillary evolved in the Siberian tundra, where P. bistorta and P. vivipara were both abundant in the past (Maresova et al, 2019). Our results are consistent with these fi ndings and may confi rm that P. bistorta was indeed one of the original larval food plants of this butterfl y and only later did some populations adapt to feeding on other species of plants when colonizing new biotopes in cold climates.…”

“…Willows are cited as larval food plants in North America (Shepard, 1975;Scott, 1986;Bird et al, 1995) and in our studies S. aurita was eaten by the larvae of both ecotypes, but they did not grow. Therefore, also taking into consideration the phylogenetic relationships between populations from both continents (Maresova et al, 2019), it is doubtful that willows could be utilized by B. eunomia in Europe.…”

A haplotype-resolved,de novogenome assembly for the wood tiger moth (Arctia plantaginis) through trio binning

“…If A. plantaginis spread from the Caucasus with a narrow founder population, as suggested in Hegna et al 2015[17], we would expect higher genetic diversity in the Caucasus compared to the other geographic regions. Similar patterns of strong genetic differentiation and low genetic diversity in Caucasus and other European mountain ranges have been observed in the Holarctic butterfly Boloria eunomia[72], which likely retreated into refugia provided by warmer micro-habitats within European mountain ranges during particularly harsh glaciation periods. Perhaps a similar scenario occurred in A.…”

Genetic confirmation of Aricia artaxerxes (Fabricius, 1793) (Lepidoptera, Lycaenidae) in the Czech Republic, its conservation significance and biogeographic context

“…Samples from the Italian Peninsula, which are still lacking in the dataset, could shed more light on this problem. The Palaearctic-wide distribution of haplogroup A could either point to a rapid postglacial expansion from a refugium, or to a more continuous distribution during glacials, as detected also for other continental species (Marešová et al 2019;Bartoňová et al 2018). We incline towards the second option, as postglacial dispersal from a restricted refugium to the wide belt stretching from the Alps to the Altai Mts.…”