Scent of a break-up: phylogeography and reproductive trait divergences in the red-tailed bumblebee (Bombus lapidarius)

Abstract

BackgroundThe Pleistocene climatic oscillations are considered as a major driving force of intraspecific divergence and speciation. During Ice Ages, populations isolated in allopatric glacial refugia can experience differentiation in reproductive traits through divergence in selection regimes. This phenomenon may lead to reproductive isolation and dramatically accentuates the consequences of the climatic oscillations on species. Alternatively, when reproductive isolation is incomplete and populations are expanding again, further mating between the formerly isolated populations can result in the formation of a hybrid zone, genetic introgression or reinforcement speciation through reproductive trait displacements. Therefore changes in reproductive traits driven by population movements during climatic oscillations can act as an important force in promoting pre-zygotic isolation. Notwithstanding, divergence of reproductive traits has not been approached in the context of climatic oscillations. Here we investigate the impact of population movements driven by climatic oscillations on a reproductive trait of a bumblebee species (Bombus lapidarius). We characterise the pattern of variation and differentiation across the species distribution (i) with five genes (nuclear and mitochondrial), and (ii) in the chemical composition of male marking secretions (MMS), a key trait for mate attraction in bumblebees.ResultsOur results provide evidence that populations have experienced a genetic allopatric differentiation, in at least three main refugia (the Balkans, Centre-Eastern Europe, and Southern Italy) during Quaternary glaciations. The comparative chemical analyses show that populations from the Southern Italian refugium have experienced MMS differentiation and an incipient speciation process from another refugium. The meeting of Southern Italian populations with other populations as a result of range expansion at a secondary contact zone seems to have led to a reinforcement process on local MMS patterns.ConclusionsThis study suggests that population movement during Quaternary climatic oscillations can lead to divergence in reproductive traits by allopatric differentiation during Ice Ages and by reinforcement during post-glacial recolonization.

Complex within a Complex: Integrative Taxonomy Reveals Hidden Diversity in Cicadetta brevipennis (Hemiptera: Cicadidae) and Unexpected Relationships with a Song Divergent Relative

“…n. profited by temporary migration routes when coastlines moved seaward due to the enormous amount of water stored in the continental ice sheets in the Late Pleistocene [102–104] as known for other organisms (e.g. [89,105–107]). Later these coastal plains were inundated again and populations were isolated and went locally extinct.…”

Genetic structuring of Anatolian Bombus lapidarius L. (Apidae: Hymenoptera) populations

“…Aynı zamanda soğuk seven, izole ve parçalı bir yayılış sergileyen bir tür olması nedeniyle filocoğrafya çalışmaları açısından da ideal bir organizmadır [23]. Taksonomik açıdan bu tür, günümüzde B. lapidarius lapidarius, B. lapidarius caucasius, B. lapidarius eriophorus, B. lapidarius decipiens ve B. lapidarius atlanticus olmak üzere beş alt taksonomik gruba ayrılmıştır [24]. Batı Palearktik'te yayılış sergileyen bu türün nominal türü Avrupa'nın ovaları, Balkanlar ve Batı Anadolu'da; B. lapidarius caucasicus Kuzeydoğu Anadolu, Transkafkasya ve İran'ın kuzeyinde, B. lapidarius eriophorus Kafkasya'da, B. lapidarius decipiens İberve Güney İtalya'da ve B. lapidarius atlanticus ise Fas'ta yayılış sergilemektedir [25].…”

Subspecific differentiation in male reproductive traits and virgin queen preferences, in Bombus terrestris

“…Ultimately, this may lead to reproductive isolation and speciation (Andersson 1994;Ptacek 2000;Nosil et al 2007). However, the extent to which population differentiation in mating cues affects species recognition has received little empirical support (Andersson 1994;Vereecken et al 2007; Lecocq et al 2013a).…”

“…Moreover, bumblebee species have been affected by biogeographic events (Williams et al 2011;Duennes et al 2012;Lecocq et al 2013a;2013b). These features of bumblebees could lead to intraspecific spatial genetic differentiation (Avise 2000) as well as to spatially varying selection regimes within species (Wright 1951) and, consequently, to evolutionary divergences (Williams 1991;Estoup et al 1996).…”

“…The CLGS are species-specific complex mixtures (mainly aliphatic compounds) dominated by few compounds with a higher concentration (main components) (Calam 1969;Svensson 1979), produced de novo by cephalic labial glands (Žáček et al 2013). CLGS locale variations have been observed among widespread bumblebee species (Terzo et al 2005;Lecocq et al 2013a), especially in Bombus terrestris (L.) Lecocq et al 2013b). However, the consequences of this interspecific differentiation on the premating recognition remain mainly unknown (but see Ings et al 2005).…”