CONICET | Buscador de Institutos y Recursos Humanos

Landscape heterogeneity and the host plant use are factors suggested to playdeterminant roles in shaping the evolutionary history of herbivorous insects.However, the role of the reconfiguration of host plants distributions linked toQuaternary climate oscillations as drivers of contemporary population geneticstructure is still poorly understood. Here, we formally examine the relativecontribution of such factors on intraspecific diversification using the SouthAmerican cactus moth, Cactoblastis cactorum, an herbivore insect specializedin the use of cacti as host plants. We assessed genomic variation using genomewideSNPs and mitochondrial data in populations sampled across a broadgeographical gradient where moths feed on different cactus species. Weintegrated demographic simulations and ecological niche modeling into alandscape genomics framework, to test alternative hypotheses of past andcurrent population connectivity for both C. cactorum and its host plants.Regions exhibiting higher genomic diversity were evaluated for congruencewith areas where suitable climatic conditions remained stable through time.Our results revealed that past spatial configuration of suitable habitat conditionsand shifts of host plants distributions are the factors that better explain theintraspecific diversification. Genomic data also supported the hypothesis thatareas of long-term habitat stability served as refugia for C. cactorum, enablingthe maintenance of high levels of genetic diversity over time. Overall, our studyhighlights the importance of integrating inter-specific interactions and theirspatio-temporal dynamics to better understand the relative importance ofabiotic and biotic factors driving the diversification processes in herbivorousinsects with broad geographical and restricted host ranges

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