Variation of Clasper Scent Gland Composition of Heliconius Butterflies from a Biodiversity Hotspot.

Male Heliconius butterflies possess two pheromone emitting structures, wing androconia and abdominal clasper scent glands. The composition of the clasper scent gland of males of 17 Heliconius and Eueides species from an overlapping area in Ecuador, comprising three mimicry groups, was investigated by GC/MS. The chemical signal serves as an anti-aphrodisiac signal that is transferred from males to females during mating, indicating the mating status of the female to prevent them from harassment by other males. In addition, the odour may also serve in predator defence. There is potential for convergence driven by mimicry, although, such convergence might be detrimental for species recognition of the butterflies within the mimicry ring, making mating more difficult. More than 500 compounds were detected, consisting of volatile, semi-volatile or non-volatile compounds, including terpenes, fatty acid esters or aromatic compounds. Several novel esters were identified by GC/MS and GC/IR data, microderivatisation and synthesis, including butyl (Z)-3-dodecenoate and other (Z)-3-alkenoates, 3-oxohexyl citronellate and 5-methylhexa-3,5-dienyl (E)-2,3-dihydrofarnesoate. The secretions were found to be species specific, potentially allowing for species differentiation. Statistical analysis of the compounds showed differentiation by phylogenetic clade and species, but not by mimicry group.

A molecularphylogeny offorktail damselflies(genus Ischnura)revealsa dynamic macroevolutionary history of female colour polymorphisms.

Colour polymorphisms are popular study systems among biologists interested in evolutionary dynamics, genomics, sexual selection and sexual conflict. In many damselfly groups, such as in the globally distributed genus Ischnura (forktails), sex-limited female colour polymorphisms occur in multiple species. Female-polymorphic species contain two or three female morphs, one of which phenotypically matches the male (androchrome or male mimic) and the other(s) which are phenotypically distinct from the male (heterochrome). These female colour polymorphisms are thought to be maintained by frequency-dependent sexual conflict, but their macroevolutionary histories are unknown, due to the lack of a robust molecular phylogeny. Here, we present the first time-calibrated phylogeny of Ischnura, using a multispecies coalescent approach (StarBEAST2) and incorporating both molecular and fossil data for 41 extant species (55% of the genus). We estimate the age of Ischnura to be between 13.8 and 23.4 millions of years, i.e. Miocene. We infer the ancestral state of this genus as female monomorphism with heterochrome females, with multiple gains and losses of female polymorphisms, evidence of trans-species female polymorphisms and a significant positive relationship between female polymorphism incidence and current geographic range size. Our study provides a robust phylogenetic framework for future research on the dynamic macroevolutionary history of this clade with its extraordinary diversity of sex-limited female polymorphisms.