Male and Female Mate Choice in Harvestmen: General Patterns and Inferences on the Underlying Processes

Abstract

Harvestmen belong to the order Opiliones, and, unlike other arachnids, they are highly polygynandrous, with both males and females mating multiply throughout the breeding season. In this chapter, we review the current information on sexual selection in the group, focusing mostly on intersexual interactions. Particularly, we provide an overview of harvestman mating systems, examine different temporal phases of male-female sexual interactions, and explore cases of sex role reversal. Several traits in harvestmen make them unique in the context of most previous studies of sexual selection. First, they have evolved an intromittent organ independently of other well-studied taxa, such as insects, spiders, and mammals. Second, the lack of long-range perception mechanisms reduces the window of opportunity for males and females to exchange information during the very short period between the first contact and intromission. In some cases, however,

All the better to bite you with! Striking intrasexual differences in cheliceral size define two male morphs in an Amazonian arachnid

“…cheliceral massage) are probably a form of pre-copulatory courtship accomplished by both male morphs to stimulate potential mating partners. This behaviour has never been reported in harvestmen (reviewed by Machado et al, 2015), but scorpion males perform a similar cheliceral massage on females before sperm transfer, and this behaviour is interpreted as pre-copulatory courtship (e.g. Carrera et al, 2009).…”

Mating behaviour and its relationship with morphological features in the millipede Pachyiulus hungaricus (Karsch, 1881) (Myriapoda, Diplopoda, Julida)

“…Considering that the male approaches the female from the dorsal side, we assume that, during the following male movements, the female receives and processes some tactile information about the male's qualities. This exchange of information established after the male begins tapping the female with its legs also presumably occurs in some Opiliones (Machado et al, 2015).…”

Qualitative and quantitative comparisons of mating behaviour across multiple populations and six species of leiobunine harvestmen (Arachnida: Opiliones)

“…The second outlines differences in mating dynamics across species in the clade that suggests inter-specific variation in selection shaping mate assessment and reproductive behaviour (Fowler-Finn et al, 2018). Combined, these two studies -in addition to work on other clades of Opiliones (Machado et al, 2015(Machado et al, , 2016 -demonstrate that mate assessment occurs over a step-wise series of male-female interactions in clearly defined pre-copulatory, copulatory, and post-copulatory stages. Furthermore, different morphological traits predict success at various stages of mating, and the traits predicting success also differ across species (Fowler-Finn et al, 2014;Fowler-Finn et al, 2018).…”