Contrasting genomic and phenotypic outcomes of hybridization between pairs of mimetic butterfly taxa across a suture zone

Abstract

Hybrid zones, whereby divergent lineages come into contact and eventually hybridize, can provide insights on the mechanisms involved in population differentiation and reproductive isolation, and ultimately speciation. Suture zones offer the opportunity to compare these processes across multiple species. In this paper we use reduced‐complexity genomic data to compare the genetic and phenotypic structure and hybridization patterns of two mimetic butterfly species, Ithomia salapia and Oleria onega (Nymphalidae: Ithomiini), each consisting of a pair of lineages differentiated for their wing colour pattern and that come into contact in the Andean foothills of Peru. Despite similarities in their life history, we highlight major differences, both at the genomic and phenotypic level, between the two species. These differences include the presence of hybrids, variations in wing phenotype, and genomic patterns of introgression and differentiation. In I. salapia, the two lineages appear to hybridize only rarely, whereas in O. onega the hybrids are not only more common, but also genetically and phenotypically more variable. We also detected loci statistically associated with wing colour pattern variation, but in both species these loci were not over‐represented among the candidate barrier loci, suggesting that traits other than wing colour pattern may be important for reproductive isolation. Our results contrast with the genomic patterns observed between hybridizing lineages in the mimetic Heliconius butterflies, and call for a broader investigation into the genomics of speciation in Ithomiini ‐ the largest radiation of mimetic butterflies.

3-Acetoxy-fatty acid isoprenyl esters from androconia of the ithomiine butterfly Ithomia salapia

“…Here we focus on the two closely related taxa, Ithomia salapia aquinia and I. s. derasa. The two subspecies have somewhat divergent wing color patterns (see Supporting Information File 1, Figure S1) [4], are widely distributed, and parapatric in north-eastern Peru [5]. Despite the geographic overlap in distribution, a recent genetic study showed limited gene flow [4].…”

“…The two subspecies have somewhat divergent wing color patterns (see Supporting Information File 1, Figure S1) [4], are widely distributed, and parapatric in north-eastern Peru [5]. Despite the geographic overlap in distribution, a recent genetic study showed limited gene flow [4]. Reproductive isolation in mimetic butterflies can be driven by multiple factors, notably non-random mating based on color pattern and/or sexual pheromones [6][7][8].…”

Spotting genome-wide pigmentation variation in a brown trout admixture context

“…While providing interesting results, comparisons using individuals from more natural populations, clades and/or subspecies within the S. trutta complex remain necessary in order to better investigate and elucidate the evolutionary history of trout regarding body colour patterns and to refine the CPL list. DdRADseq used in this study is however a reduced representation sequencing technique targeting only a tiny portion of the genome (∼1%) that is considered either to successfully target (Belsford et al, 2017) or miss important loci responsible for colour and pigmentation patterns (Gauthier et al, 2020). Thus, RNA sequencing or gene expression studies promoted by Djurdjevič et al (2019), together with more standard association studies in control settings that, as for other traits, may provide better estimates of QTL number (if any), variation in effect sizes among loci and more accurately pointing key master genes (e.g.…”

Novel 3-Acetoxy Fatty Acid Isoprenyl Esters from Androconia of the Ithomiine Butterfly Ithomia salapia

“…The two subspecies have somewhat divergent wing color patterns (see Supporting Information, Figure S1) [4], are locally abundant, widely distributed, and are parapatric in north-eastern Peru (San Martin) [5]. Despite the geographic overlap in distribution, a recent genetic study showed limited gene flow [4].…”

“…The two subspecies have somewhat divergent wing color patterns (see Supporting Information, Figure S1) [4], are locally abundant, widely distributed, and are parapatric in north-eastern Peru (San Martin) [5]. Despite the geographic overlap in distribution, a recent genetic study showed limited gene flow [4]. Reproductive isolation in mimetic butterflies can be driven by multiple factors, notably non-random mating based on color pattern and/or sexual pheromones [6][7][8].…”