Female Colour Polymorphism and Unique Reproductive Behaviour in Polythore Damselflies (Zygoptera: Polythoridae)
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ECOLOGY, BEHAVIOR AND BIONOMICS
Female Colour Polymorphism and Unique Reproductive Behaviour in Polythore Damselflies (Zygoptera: Polythoridae) I SANMARTÍN-VILLAR, A CORDERO-RIVERA ECOEVO Lab, Escola de Enxeñaría Forestal, Univ de Vigo, Pontevedra, Galiza, Spain
Keywords Jatun Sacha Biological Reserve, Odonata, wing colour polymorphism, copulation Correspondence I Sanmartín-Villar, ECOEVO Lab, Escola de Enxeñaría Forestal, Univ de Vigo, Campus A Xunqueira, 36005 Pontevedra, Galiza, Spain; [email protected] Edited by Ranyse B Querino – Embrapa Received 11 January 2016 and accepted 24 May 2016 * Sociedade Entomológica do Brasil 2016
Abstract We studied Polythore damselflies by mark-recapture techniques in the Jatun Sacha Biological Reserve (Ecuador) for a period of 48 days in October–December 2014. Three species were found: Polythore mutata (MacLachlan) was the commonest species (111 individuals marked), Polythore derivata (MacLachlan) was rare (24 individuals) and Polythore concinna (MacLachlan) occasional (four individuals). In P. mutata, we found two phenotypes amongst females, one of them with a white band on the wings, very similar in colouration to the conspecific male (androchrome), and the other with an amber band (gynochrome). The recapture of marked females indicates that both phenotypes are maintained since emergence to maturation and are not age-related (i.e. polymorphism). Androchromes represent 40% of females observed. The colour of the wing band showed an age-dependent change in size with opposite trends between sexes, increasing in males and decreasing in females. Males and females were observed to return to the same forest locations in different days. Courtships and ovipositions involving androchrome females were not observed. No matings were observed in any morph. In contrast, we recorded two consecutive matings of one female P. derivata. We found that Polythore males grasp the mesothorax of females during mating instead of the prothorax as in other Zygoptera. We discuss the rarity of reproductive behaviour in this genus and how female morphs might be maintained.
Introduction The maintenance of genetic variability in natural populations is a central topic in evolutionary biology. Many studies have shown that mechanisms like frequency or density-dependent selection and spatial and temporal variation in the strengths and direction of selection are able to maintain variability due to the impossibility of gene pools to perfectly match a variable environment (Stewart & Lees 1996). Colour polymorphisms are a classic example in this context, given their conspicuous appearance, and have provided long-standing examples of the action of Natural Selection maintaining variability (for example, industrial melanism; Cook et al 2002).
Colour polymorphism is widespread in the Odonata, but is mainly restricted to females (Cordero & Andrés 1996, Fincke et al 2005). Most of our knowledge about this phenomenon comes from studies of the family Coenagrionidae in temperate regions. Nevertheless, this polymorphism is a
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