The development of sexual differences in body size in Odonata in relation to mating systems

Abstract

Abstract. Adult body size is the result of important environmental, maternal and/or genetic effects acting on animals during development. Here we investigate how sexual size dimorphism (SSD) develops in seven species of Odonata: Anax imperator, Cordulegaster boltonii, Onychogomphus uncatus, Oxygastra curtisii (Anisoptera), Cercion lindeni, Ischnura graellsii and Platycnemis acutipennis (Zygoptera). SSD of both the last larval and adult stages of the same individuals, which were reared under laboratory conditions, was measured. The aims were to investigate (i) whether SSD develops during the larval stage, (ii) the direction of larval and adult SSD, and (iii) whether the direction of adult SSD can be predicted by the mating system of a given species (e.g. males of territorial species being larger than females and the opposite for non-territorial species). We found that although larval differences in size may be present between the sexes, these are not necessarily shown in the adult stage (they may change or disappear). Also, the mating system was not related to patterns of adult SSD. Differences in SSD in larvae may be caused by differential use of resources via differential niche-utilisation or sex-specific growth patterns. We highlight the fact that sexual selection favouring large male size and fecundity selection, which selects for large females may be acting on the observed patterns in SSD in adults.

Emergence ecology and body size dimorphism in Sympetrum fonscolombii and S. meridionale (Odonata: Libellulidae)

“…Body and wing sheath lengths showed male-biased SSD in S. meridionale, but reversed SSD patterns in S. fonscolombii, that is, males had a longer body but shorter wings. A positive relationship between larval and adult size was found in odonates (Serrano-Meneses, Azpilicueta-Amorín et al 2007), which means that our findings are likely to be applicable to the adult stage. SSD was greater in the larger species S. meridionale than in the smaller species S. fonscolombii which is concordant with the Rench's rule (Johansson, Crowley, and Brodin 2005); however, to confirm this hypothesis, it would be necessary to increase the sample size in terms of the species number.…”

Perilaku bertelur dan pemilihan habitat bertelur oleh capung jarum Pseudagrion pruinosum (Burmeister) (Odonata: Coenagrionidae)

“…Hubungan suhu udara dengan perilaku bertelur, bisa dijelaskan dengan hasil penelitian Samejima & Tsubaki (2010) yang membuktikan bahwa jantan dengan wilayah teritori yang terpapar oleh sinar matahari langsung mempunyai kemampuan terbang lebih tinggi daripada pejantan lain yang wilayah teritorinya ternaungi oleh tumbuhan. Performa terbang pada capung jarum penting untuk keberhasilan jantan dalam memperoleh betina (Neems et al 1998;Serrano-Meneses et al 2007) melalui keberhasilan kompetisi antar jantan (Marden & Cobb 2004;Moya-Larano et al 2007), dan perilaku pendekatan untuk kawin terhadap pasangannya (Marden 1989), dan kewaspadaan terhadap serangan predator selama kawin (Almbro & Kullberg 2009). Keberhasilan kawin capung P. pruinosum selanjutnya diikuti oleh perilaku peletakkan telur dan umumnya betina meletakkan telur di lokasi yang tidak jauh dengan lokasi kawin.…”

Biometry of the large dragonfly Anax imperator (Odonata: Aeshnidae): A study of traits from larval development to adults

“…rial species (Anholt et al, 1991;Grether, 1996;Serrano-Meneses et al, 2007;Samejima & Tsubaki, 2010). Usually, in odonates, large individuals appear to be generally fi tter (Sokolovska et al, 2000), but this trend is probably counterbalanced by stabilizing selection (Thompson & Fincke, 2002).…”