title: Androgen responses to reproductive competition of males pursuing either fixed or plastic alternative reproductive tactics.
abstract: Alternative reproductive tactics (ARTs), which can be plastic or fixed for life, may be characterized by distinct hormonal profiles. The relative plasticity hypothesis predicts flexible androgen regulation for adult males pursuing plastic tactics, but a less flexible regulation for males using a fixed tactic throughout life. Furthermore, androgen profiles may respond to changes in the social environment, as predicted by the social reciprocity models of hormone/behaviour interactions. The cichlid fish Lamprologus callipterus provides a rare opportunity to study the roles of androgens for male ARTs within a single species, because fixed and plastic ARTs coexist. We experimentally exposed males to competitors pursuing either the same or different tactics to test predictions of the relative plasticity and the social reciprocity models. Androgen profiles of different male types partly comply with predictions derived from the relative plasticity hypothesis: males of the plastic bourgeois/sneaker male trajectory showed different 11-ketotestosterone (11-KT) levels when pursuing either bourgeois or parasitic sneaker male behaviours. Surprisingly, males pursuing the fixed dwarf male tactic showed the highest free and conjugated 11-KT and testosterone (T) levels. Our experimental social challenges significantly affected the free 11-KT levels of bourgeois males, but the androgen responses did not differ between challenges involving different types of competitors. Furthermore, the free T-responses of the bourgeois males correlated with their aggressive behaviour exhibited against competitors. Our results provide new insights into the endocrine responsiveness of fixed and plastic ARTs, confirming and refuting some predictions of both the relative plasticity and the social reciprocity models.
authors.affiliation: Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, Wohlenstr. 50a, 3032 Hinterkappelen, Switzerland corinna.vonkuerthy@iee.unibe.ch.
authors.forename: Corinna
authors.identifier: 0000-0002-8679-1696
authors.initials: C
authors.lastname: von Kuerthy
authors.affiliation: Laboratoire d'éco-éthologie, Université de Neuchâtel, Av. du 1er-Mars 26, 2000 Neuchâtel, Switzerland.
authors.forename: Albert F H
authors.initials: AF
authors.lastname: Ros
authors.affiliation: Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, Wohlenstr. 50a, 3032 Hinterkappelen, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Taborsky
mesh_terms: D000374:Aggression / Q000187:drug effects; D000728:Androgens / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D023681:Cichlids / Q000254:growth & development / Q000502:physiology*; D008018:Life Cycle Stages / Q000187:drug effects; D008297:Male; D012098:Reproduction / Q000187:drug effects*; D012919:Social Behavior; D013739:Testosterone / Q000378:metabolism
chemical_list: D000728:Androgens; D013739:Testosterone
keywords: 11-ketotestosterone; Alternative reproductive tactics; Androgens; Relative plasticity hypothesis; Social environment; Social reciprocity models; Testosterone