North-Western Journal of Zoology Vol. 4, No. 2, 2008, pp.327-330 [Online: Vol.4, 2008: 27]

Multiple amplexus in the Iberian Brown Frog Rana iberica

Cesar AYRES

ROAGA-CINAM, Centro de Investigación e Información Ambiental – Lourizán, Estrada PO-546 Pontevedra-Marín, km. 4. Apdo. de Correos 127- C.P. 36080, Lourizán - Pontevedra- Spain, E-mail: [email protected]

Abstract. On February 29th 2008 I found a breeding aggregation of the Iberian Brown Frog in a small pond in Lourizan, Pontevedra, NW Spain. I observed at least five males trying to grasp one female. Multiple amplexus is not common in Rana iberica, and studies are needed to collect information about the extent of this behaviour.

Key words: Rana iberica, multiple amplexus, NW Spain.

Rana iberica is an endemic brown frog e Informacion Ambiental (CINAM) has from the Iberian Peninsula, occupying started. This forest is located near cold streams, ponds and mountain lakes Pontevedra, NW Spain, 57 m a.s.l., in the Northern and Western parts of 29TNG29. Reproduction of amphibians Spain and Portugal, with some isolated was detected in streams and also in some sites in the mountains of Sistema Central artificial ponds. Salamandra salamandra, from Central Spain (Salvador and Garcia- Lissotriton helveticus, Triturus marmoratus Paris, 2001). and Rana iberica were detected in high The breeding behaviour of this numbers; Lissotriton boscai and Rana perezi species is not well known. In NW Spain were scarcer. and Portugal the breeding season ranges On February 29th 2008 at 12:50 an from November to March in the unusual aggregation of R. iberica lowlands, and March-April in the individuals was detected in a small pond highlands (Crespo & Cei 1971, Galan after a cascade, no more than 10 cm deep, 1982), with a peak in March-April (Galan with refuges under stones, and high 1982). According to previous findings coverage of dead leaves. At least five (e.g. Galan 1982, Nöllert & Nöllert 1995) individuals were trying to clasp a big the amplexus occurs at night. However, it female (Fig. 1). Another male was resting seems possible that some breeding on the water surface close to the activity occurs also at daylight, as it is reproductive aggregation. Some of the described in this work. There is few data males hid away at the disturbance, but about reproductive aggregations (Nöllert two males remained in amplexus, the & Nöllert 1995) in R. iberica, but to our larger one in the usual axilar amplexus, knowledge no one reports multiple but the smaller one was clasping the amplexus in this species . female in inguinal amplexus (Fig. 2). This In 2008, herpetological monitoring of male tried to get into axilar amplexus the forest inside Centro de Investigacion going under the other male, both males

North-West J Zool, 4, 2008 Oradea, Romania 328 Ayres, C.

Figure 1. Several individual trying to clasp a big female.

Figure 2. Two males in amplexus, one attached by inguinal amplexus, and the other by axilar amplexus.

North-West J Zool, 4, 2008 Multiple amplexus in the Iberian Brown Frog Rana iberica 329

used hind legs to fight for the position. with low numbers of breeding indi- The female rested motionless at the viduals and should reduce the hetero- bottom of the pond, with its nose zygote deficit related to the breeding pointing to the surface, curving its body. pond fidelity usually exhibited by most At 14:30 the pond was surveyed again, anurans (Lodé & 2004, Lodé et al. 2005), and only the bigger male remained but other argue that costs of multiple attached to the female, both resting on amplexus, including risk of drowning, is the water surface and hiding under higher than possible advantages (Byrne stones at the disturbance. First ovated & Roberts 1999, 2000, Sztatecsny et al. females were found in mid-October 2007 2006, Lengagne et al. 2007). Nevertheless, in other streams of Galicia region, and no multiple mating could be advantageous more amplexus or egg-masses were for females by potentially increasing found after this episode in CINAM fertilisation, sperm quality or offspring stream. genetic diversity (Roberts et al. 1999). Multiple amplexus is especially Also it seems that multiple mating could common in explosive breeding amphi- be influenced by sex-biased predation bians where a large number of breeding that changes OSR (Lodé et al. 2004). adults can be present in the breeding site Because of their pond fidelity anurans for a short time period (days to weeks). are affected by heterozygote deficit In these species, females are important (Lesbarrères et al. 2003), and it may be resources for males because at least 2 suggested that polyandrous mating reasons: (i) the males are present in larger results in inbreeding avoidance. In a number than females even from the start species with high site fidelity and low of the breeding season and (ii) the males dispersal, as R. iberica (Rodríguez-Prieto breed with more females whereas the & Fernández-Juricic 2005), multiple females leave the pond in short time after mating could improve gene flow in small the eggs were laid (Hartel et al. 2007). populations. Further studies, including Thus the operational sex ratio (OSR) may molecular techniques, will be necessary be strongly male biased in these cases to assess if this hypothesis is true. resulting in an intense competition between males to obtain a mate. This competition may result in multiple amplexus, takeovers, and frequently, the References death of females, as it was observed for Ayres, C. (2008): Post-mortem amplexus in marauded example in B. bufo (Hartel et al. 2007, Bufo bufo (Linnaeus, 1758). Podarcis 9 (In press). Ayres 2008). Byrne, P.G., Roberts, J.D. (2000): Does multiple paternity improve fitness in the frog Crinia georgiana? Multiple amplexus resulted in Evolution 54: 968-973. multiple paternity if fertilization occurs Byrne, P.G. and Roberts, J.D. (1999): Simultaneous in the red-eyed tree-frog, Agalychnys mating with multiple males reduces fertilisation success in the myobatrachid frog Crinia georgiana. callidryas, as revealed by DNA finger- Proceedings of the Royal Society of London B. 264: printing (D’Orgeix & Turner 1995). Some 95-98. Crespo, E.G., Cei. J.M. (1971): L'activité spermato- authors argue that multiple mating génetique saisonniere de Rana iberica Boul. du nord system could be advantageous for species de Portugal. Arquivos do Museo Bocage (2ª Serie) 3: 37-50.

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