Reproductive biology of harvestmen(Arachnida:Opiliones):a review of a rapidly evolving research field

Harvestmen are a major arachnid order that has experienced a dramatic increase in biological knowledge in the 21st century.The publication of the book Harvestmen:The Biology of Opiliones in 2007 stimulated the development of many behavioral studies.Although the book is relatively recent,our understanding of the reproductive biology of harvestmen is already outdated due to the fast accumulation of new data.Our goal is to provide an updated review of the subject to serve as a benchmark for the following years.In the pre-copulatory phase,we explore the evolu-tion of facultative parthenogenesis,the factors that may affect the types of mating system,and the role of nuptial gifts in courtship.Regarding the copulatory phase,harvestmen are unique arachnids because they have aflagellate spermatozoa and a penis with complex morphology.We discuss the implications of these two features for sperm competition and cryptic female choice.In the post-copulatory phase,we connect ovi-position site selection and climate conditions to the widespread occurrence of resource defense polygyny,alternative reproductive tactics,and sexual dimorphism in several clades of tropical harvestmen.Finally,we present the different forms of parental care in the order,and discuss the benefits and costs of this behavior,which can be performed either by females or males.Throughout the review,we indicate gaps in our knowl-edge and subjects that deserve further studies.Hopefully,the information synthesized here will stimulate researchers worldwide to embrace harvestmen as a study system and to improve our effort to unravel the mysteries of their reproductive biology.

Short-and long-term effects of an extreme case of autotomy:does“tail”loss and subsequent constipation decrease the locomotor performance of male and female scorpions?

In many taxa,individuals voluntarily detach a body part as a form to increase their chances of escaping predation.This defense mechanism,known as autotomy,has several consequences,such as changes in locomotor performance that may affectfitness.Scorpions of the genus Ananteris autotomize the“tail”,which in fact corresponds to the last abdominal segments.After autotomy,individuals lose nearly 25%of their body mass and the last portion of the digestive tract,including the anus,which prevents defecation and leads to constipation,because regeneration does not occur.Here,we experimentally investigated the short-and long-term effects of tail loss on the locomotor performance of Ananteris balzani.In a short-term experiment,the maximum running speed(MRS)of males and females did not change after autotomy.Moreover,the relative mass of the lost tail did not affect the change in MRS after autotomy.In a long-term experiment,autotomy had a negative effect on the MRS of males,but not of females.Autotomized over-fed individuals suffered from severe constipation but were not slower than autotomized normally fed individuals.In conclusion,tail loss has no immediate effect on the locomotor performance of scorpions.The long-term decrease in the locomotor performance of autotomized males may impair mate searching.However,because death by constipation takes several months,males have a long time tofind mates and reproduce.Thus,the prolonged period between autotomy and death by constipation is crucial for understanding the evolution of one of the most extreme cases of autotomy in nature.