All-year reproduction and possible thermal melanism in Amblystogenium pacificum (Coleoptera : Carabidae) on the Sub-Antarctic Ile de la Possession (Iles Crozet)

• Main Authors: Davies, Lavis, Bouvet, Sophie, Vernon, Philippe
• Other Authors: Ecosystèmes, biodiversité, évolution Rennes (ECOBIO), Université de Rennes (UR)-Institut Ecologie et Environnement - CNRS Ecologie et Environnement (INEE-CNRS), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2007
• Subjects: Amblystogenium · Carabidae · Sub-Antarctic · Reproduction · Age composition · Thermal melanism · Dimorphism; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; Antarctic; Antarc*; Polar Biology
• Online Access: https://hal.science/hal-00132818

International audience In the fell-Weld habitat at 140–270 m altitude on the sub-Antarctic Ile de la Possession, Iles Crozet, the dimorphic beetle Amblystogenium pacificum Putzeys (Coleoptera: Carabidae) was studied monthly throughout the southern year 1993–1994 by timed hand collections involving turning stones on the rocky fell-Weld. There were many mating couples and females containing well-developed eggs in every month and the species reproduced throughout the year, with no evidence of a winter cessation of egg production. However, the frequency of mating couples was about twice as great in the summer half-year (October–March) as in the winter half (April–September). Relatively small differences in monthly mean temperatures between the summer and winter at Iles Crozet render all-year reproduction not unexpected when comparisons are made with the temperatures and phenology of Carabidae in cool habitats in other parts of the world. Mating pairs were collected at unusually high frequencies for carabids. The frequency of such pairs, taken per unit eVort by hand collecting, was highest in October–December, lower from January to May and intermediate from June to September. Comparison of beetles taken as solitary, non-mating individuals with those taken as mating couples showed that in summer, females of the black morph of this dimorphic species were more frequently involved in mating than expected, but no differences were detected in winter. Female beetles were divided into younger individuals (putative age 1–2 years) and older females (putative age 3–5 years or more) by the amount of claw-wear on individuals of this species. This division indicated that about 40% of the older females showed no egg development when captured, but only about 20% of the younger females were non-breeding. However, of the reproducing beetles, young and old females matured similar numbers of eggs. An altitude transect showed that the proportion of the black morph increased significantly with altitude. Studies at 140–270 m showed that ...