The choice of breeding sites by pond-breeding anurans has notable consequences for the fitness of larvae. Hence, beyond pond typology and phenology, adults can also discriminate according to several other features, for instance to favour allotopy with potential competitors. However, the lack of shared evolutionary history might impede proper ecological differentiation with alien species during the first stages of invasions. Here, we studied several possible sources of ecological segregation between the invasive Discoglossus pictus and the native Epidalea calamita in ephemeral ponds, where the native toad hardly had competition before the arrival of the invasive frog. During spring of 2016, we periodically surveyed 69 ephemeral ponds in three areas with different invasion histories to detect the presence/absence of eggs and tadpoles of these species. Invasive D. pictus started breeding earlier than E. calamita, but differences were not significant. Similarly, there were not clear differences among areas with different invasion histories. However, we found for both species a mutual tendency to directly avoid larval syntopy at the end of the reproductive season. We also found interspecific differences in the features that both species use for pond choice, preferring the native species shallower and less vegetated ephemeral ponds. Globally however, co-occurrence was high, pointing at other processes as key to the coexistence between both species in these habitats.
CadiA.JolyP. (2004): Impact of the introduction of the red-eared slider (Trachemys scripta elegans) on survival rates of the European pond turtle (Emys orbicularis). Biodivers. Conserv.13 (13): 2511-2518.
CalcagnoV. (2013): Glmulti: model selection and multimodel inference made easy. R package version 1.0.7. https://CRAN.R-project.org/package=glmulti.
CayuelaH.BesnardA.BechetA.DevictorV.OlivierA. (2012): Reproductive dynamics of three amphibian species in Mediterranean wetlands: the role of local precipitation and hydrological regimes. Freshwat. Biol.57: 2629-2640.
FinstadA.G.ForsethT.JonssonB.BellierE.HesthagenT.JensenA.J. ... FoldvikA. (2011): Competitive exclusion along climate gradients: energy efficiency influences the distribution of two salmonid fishes. Global Change Biol.17 (4): 1703-1711.
MoreyS.R.ReznickD.N. (2004): The relationship between habitat permanence and larval development in California spadefoot toads: field and laboratory comparisons of developmental plasticity. Oikos104 (1): 172-190.
OksanenJ.BlanchetF.G.KindtR.LegendreP.MinchinP.R.O’HaraR.B.SimpsonG.L.SolymosP.HenryM.StevensH.WagnerH. (2016): vegan: community Ecology Package. R package version 2.3-5. https://CRAN.R-project.org/package=vegan.
PearmanP.B. (1995): Effects of pond size and consequent predator density on two species of tadpoles. Oecologia102 (1): 1-8.
PetrankaJ.W.HopeyM.E.JenningsB.T.BairdS.D.BooneS.J. (1994): Breeding habitat segregation of wood frogs and American toads: the role of interspecific tadpole predation and adult choice. Copeia: 691-697.
Richter-BoixA.LlorenteG.A.MontoriA. (2006): A comparative analysis of the adaptive developmental plasticity hypothesis in six Mediterranean anuran species along a pond permanency gradient. Evol. Ecol. Res.8 (6): 1139-1154.
Richter-BoixA.GarrigaN.MontoriA.FranchM.San SebastiánO.VilleroD.LlorenteG.A. (2013): Effects of the non-native amphibian species Discoglossus pictus on the recipient amphibian community: niche overlap, competition and community organization. Biol. Inv.15 (4): 799-815.
ZangariF.CimmarutaR.NascettiG. (2006): Genetic relationships of the western Mediterranean painted frogs based on allozymes and mitochondrial markers: evolutionary and taxonomic inferences (Amphibia, Anura, Discoglossidae). Biol. J. Linn. Soc.87 (4): 515-536.