Female mate choice in the intertidal crab Neohelice granulata (Brachyura: Varunidae).

SAL MOYANO M. P.; SILVA P; LUPPI T. A.; GAVIO M. A.

Atenas

Congreso; 10th Colloquium Crustacea Decapoda Mediterranea.; 2012

The Crustacean Society

FEMALE MATE CHOICE IN THE INTERTIDAL CRAB NEOHELICE GRANULATA (BRACHYURA: VARUNIDAE). Sal Moyano M.P.1, Silva P.1, Luppi T.*1, Gavio A.1 1Instituto de Investigaciones Marinas y Costeras (IIMyC), CONICET. Universidad Nacional Mar del Plata, Funes 3350, Mar del Plata, Argentina. salmoyan@mdp.edu.ar Introduction Information about the roles of both sexes in pair formation is required to better understand the mechanisms involved in sexual selection. Mate choice could be based in intrinsic factors such as the physical size and the reproductive status, while extrinsic ones involve visual, acoustic or chemical signals. Here we determined if Neohelice granulata mate choice is base on female or male election, considering visual and chemical signals and different categories of individuals: receptive/unreceptive females, large/small males, and mated/unmated males. Material and methods Visual and chemical signals were studied. For chemical signals, two different criteria were considered: the liberation of chemical signals to water -without contact between partners-, and through cuticle pores ?involving contact between partners-. To test signals, plastic cylinders (12cm diameter) were used in three treatments: (1) transparent without perforations -visual signal-, (2) opaque with perforations of 1cm2 allowing the individual inside to protrude the chela or legs -chemical with contact signal-, and (3) opaque with perforations of 2mm2 avoiding the crab inside to protrude parts of its body -chemical without contact signal-. According to the treatment, two cylinders were placed in a communal plastic aquarium (1x0.4x0.15m), and different levels of water were reached: (1) 3cm, (2) 1cm, and (3) 3cm. Rounding each circular base of the cylinders at a distance of 3cm, a circle was drawn in the aquarium. Four experiments were performed to test mate choice: [1] a small and a large male located each one in a cylinder + a receptive test female, [2] a receptive and an unreceptive female of similar size + an unmated test male, [3] an unmated and a mated male of similar size + a receptive test female, and [4] a receptive and an unreceptive female of similar size + a mated test male. Test crabs were located in the centre of the aquarium at a similar distance from the two cylinders and the time spent inside the drawn circles was counted and considered as the dependent variable. Paired t-tests were performed. Results No differences were found in the time spent by the test receptive female between large and small males regarding the visual (V) signal (tV=1.49; p=0.17), while differences were found regarding both chemical signals, with (WC) and without (WOC) contact: receptive females preferred larger males (tWC=3.61, p