Sex-role-reversal
Guides
Allocosa
Allocosa is a genus of wolf spiders (family Lycosidae) comprising over 130 described species with a distribution centered in the Americas. The genus was established by Nathan Banks in 1900 and has been the subject of taxonomic revision, with African species assignments remaining uncertain and requiring re-examination. Several well-studied species, including Allocosa brasiliensis, A. alticeps, and A. senex, exhibit notable sex-role reversal in mating systems, where females actively seek male burrows and initiate courtship. These spiders are ground-dwelling burrowers, often inhabiting sandy coastal or dune environments.
Anabrus
Mormon cricket
Anabrus is a genus of shield-backed katydids in the family Tettigoniidae, comprising four described species including the extinct Anabrus caudelli. The genus is best known for Anabrus simplex, commonly called the Mormon cricket, a large flightless insect famous for forming massive migratory bands that cause significant agricultural damage in western North America. Despite the common name, these insects are not true crickets but katydids characterized by their gregarious behavior, distinctive morphology, and periodic population outbreaks.
Anabrus simplex
Mormon Cricket
Anabrus simplex, commonly known as the Mormon cricket, is a large flightless shieldbacked katydid (family Tettigoniidae, subfamily Decticinae) native to western North America. Despite its common name, it is not a true cricket. The species is notable for its periodic outbreak populations that form large migratory bands, causing significant damage to rangeland forage and cultivated crops. It exhibits a sex-role reversed mating system where males provide nuptial gifts and females compete for mates. The species has been documented from low-elevation sagebrush steppe to alpine tundra above 11,000 feet.
Empidinae
dance flies
Empidinae, commonly called dance flies, are a subfamily of predatory empidoid flies. Males of many species form mating swarms near visual markers, often presenting captured prey to females as nuptial gifts during courtship. The subfamily exhibits diverse mating systems, including lek polygyny and sex-role reversal where females swarm and males choose mates. Many species are effective pollinators of flowering plants, particularly in alpine and subalpine ecosystems where they can achieve pollination effectiveness comparable to honeybees.
Leptuca crenulata
Mexican fiddler crab
The Mexican fiddler crab is a small intertidal crab formerly classified in the genus Uca but transferred to Leptuca in 2016. Females exhibit active mate searching behavior, which is notable as this represents a reversal of typical sex roles in fiddler crabs where males usually search for mates. The species inhabits intertidal mudflats and shows the characteristic sexual dimorphism of fiddler crabs, with males possessing one greatly enlarged claw used for signaling and combat.
Micromalthus debilis
Telephone-pole Beetle
Micromalthus debilis is a small beetle native to eastern North America and the sole living representative of the family Micromalthidae, often considered a 'living fossil'. The species exhibits one of the most unusual reproductive strategies in Coleoptera: obligate paedogenesis, where reproduction occurs exclusively through parthenogenetic female larvae without production of fertile adults. Adults are vestigial, sterile, and rarely encountered in nature; they can be artificially induced through heat treatment but cannot reproduce. The species is associated with decaying wood and fungal near-red-rot habitats.
Rhamphomyia
dance flies
Rhamphomyia is a large genus of dance flies (Empididae) comprising over 600 species arranged in 8 subgenera. The genus exhibits remarkable diversity in mating systems, including sex-role reversal where females compete for mates and males provide nuptial gifts. Several species display elaborate visual ornaments used in courtship, such as inflatable abdominal sacs and modified leg scales. The genus has a cosmopolitan distribution with particular diversity in the Holarctic region, including specialized radiations in arctic tundra environments.
Rhamphomyia longicauda
Long-tailed Dance Fly
Rhamphomyia longicauda is a dance fly species renowned for its exceptional sex-role reversal in mating behavior. Females form aerial leks at dawn and dusk, displaying inflated abdominal sacs and ornamental leg scales to attract males, who are the choosy sex. Females are obligate recipients of nuptial gifts—prey items captured by males—because they cannot hunt for themselves. This nutritional dependence drives the reversal of typical courtship roles. The species has been extensively studied as a model for sexual selection and the evolution of female ornamentation.
Trimerotropis agrestis agrestis
Trimerotropis agrestis agrestis is a desert grasshopper subspecies in the family Acrididae. It has been studied for its unusual mating behavior involving presumed sex-role reversal, where females initiate aerial pursuits of males during flight displays. The subspecies occurs in arid western North American habitats and has been documented to hybridize with Trimerotropis maritima in disturbed environments.