title: Extra Molting and Selection on Nymphal Growth in the Desert Locust.
abstract: In insects, extra-molting has been viewed as a compensatory mechanism for nymphal growth that contributes to optimize body weight for successful reproduction. However, little is known on the capacity of extra-molting to evolve in natural populations, which limits our understanding of how selection acts on nymphal growth. We used a multi-generational pedigree, individual monitoring and quantitative genetics models to investigate the evolution of extra-molting and its impact on nymphal growth in a solitarious population of the desert locust, Schistocerca gregaria. Growth compensation via extra-molting was observed for 46% of the females, whose adult weight exceeded by 4% that of other females, at a cost of a 22% longer development time. We found a null heritability for body weight threshold only, and the highest and a strongly female-biased heritability for extra molting. Our genetic estimates show that (1) directional selection can act on growth rate, development time and extra-molting to optimize body weight threshold, the target of stabilizing selection, (2) extra-molting can evolve in natural populations, and (3) a genetic conflict, due to sexually antagonistic selection on extra-molting, might prevent its fixation. Finally, we discuss how antagonistic selection between solitarious and gregarious environments and/or genetic correlations between growth and phase traits might also impact the evolution of extra-molting in locusts.
authors.affiliation: CIRAD, UMR CBGP, F-34398, Montpellier, France.
authors.forename: Benjamin
authors.identifier: 0000-0001-8705-7023
authors.initials: B
authors.lastname: Pélissié
authors.affiliation: CIRAD, UMR CBGP, F-34398, Montpellier, France.
authors.forename: Cyril
authors.initials: C
authors.lastname: Piou
authors.affiliation: CIRAD, UMR CBGP, F-34398, Montpellier, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Jourdan-Pineau
authors.affiliation: CIRAD, UPR B-AMR, F-34398, Montpellier, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Pagès
authors.affiliation: CIRAD, UPR B-AMR, F-34398, Montpellier, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Blondin
authors.affiliation: CIRAD, UMR CBGP, F-34398, Montpellier, France.
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Chapuis
mesh_terms: D000818:Animals; D001835:Body Weight; D003889:Desert Climate; D006110:Grasshoppers / Q000254:growth & development*; D018978:Molting / Q000502:physiology*; D009758:Nymph / Q000254:growth & development*; D010829:Physiological Phenomena; D012098:Reproduction / Q000502:physiology*