On the role of niche specialization in the geographic distribution of aphid asexual lineages: a case study using the leaf‐curl plum aphid superclones

Asexual lineages often exhibit broad distributions and can thrive in extreme habitats compared to their sexual counterparts. Several hypotheses can be proposed to explain this pattern. Asexual lineages could be versatile genotypes with wide environmental tolerance, enabling their dispersal and persistence across large geographic areas. Alternatively, asexual genotypes could be ecological specialists that thrive in specific environments and outcompete relative colonizing distantly related with similar conditions in the process. Several aphid species feature widespread obligate asexual lineages, commonly known as ‘superclones'. Yet it is often unknown whether these clones are widespread ecological generalists or successful specialists. To explore these hypotheses, we examined climatic niche differentiation among six globally distributed obligate asexual lineages of the cosmopolitan aphid pest, Brachycaudus helichrysi. To ensure that we were investigating the aphid genotype niche and not a by‐product of their association with endosymbionts mediating thermal tolerance, we first verified that clones hosted similar endosymbiont communities. Subsequently, we conducted multivariate analyses on clone occurrence data on a worldwide scale. Our results revealed that, despite their global distribution, B. helichrysi superclones occupy different climatic niches. This study represents the first evidence that aphid superclone distribution can be mediated by distinctive ranges of climatic tolerance.