Rana dalmatina

 Since their appearance at Devonian, Amphibians diverged in numerous species differing in their genetic pool. Within a species distinct populations also exhibit genetic variability. This differentiation (polymorphism) may either lead to speciation (new species birth) or favour local adaptation. Our goals deal with evolutionary ecology in numerous topics:

Population structure and gene flow

Agile frogs Rana dalmatina are terrestrial Anuran inhabiting natural meadows and woods

Population structure and gene flow can be influenced by habitat distribution. Agile frogs gathered in spawning ponds from February to the beginning of April and chorused over a two week time. During breeding time, males often predominated in populations but were intensively preyed upon by predators especially Polecats. The predation reducing population exchanges may result in differentiation among frog populations.

Sexual conflict and Polyandry in Agile frogs

 

Amplexus in Agile frog
 

Questions: Understanding why females mate multiply is a major issue in evolutionary ecology. Does the operational sex ratio influence reproductive success and offspring survival ?

Reproductive success of agile frog (Rana dalmatina) was surveyed at breeding sites. Variations in the adult sex ratio and operational sex ratio did affect reproductive success. Asynchronous arrival at breeding sites resulted in a male-biased operational sex ratio (OSR). The OSR was more strongly male-biased at the beginning and at the end of the breeding period when the number of satellite males increased.

In Rana dalmatina, the increase in male biased operational sex ratio and in male abundance results in a strong emergence of alternative male mating behaviour in the form of searching, and sneaking. As a consequence, females are coerced into mating with multiple males, which in turn increases the level of conflict between the sexes (sexual conflict).

All females mated at least once, but genetic evidence for multiple paternity within clutches occurred at the beginning and the end of the breeding period. The influence of asynchronous arrival and biased sex ratio entailed reduced variance and bet-hedging. The conflict of interest between the two sexes was the focus for the alteration in reproductive success as revealed by the number of emergent froglets.
 

Predation influences monoandry in frogs !

 Furthermore, predation by polecats Mustela putorius was found to influence sex ratio, male abundance and sexual conflict in frog mating system, restricting the opportunity for multiple mating.

 
Polecat predation upon frog

Such an exceptional interaction, resulting in sexual system changes, was demonstrated for the first time in polecat-frog (predator-prey) co-existence strategies. 

Road effect and Amphibian conservation
 

In populations of Agile frog, the observed heterozygosity was significantly lower than expected in all cases, and the strong mortality gives new evidence of a depression in small populations exposed to roads. It especially occurred in ponds located near an highway rather than in undisturbed populations. Our results argue for a “road effect zone” and emphasize the importance of management measures such as amphibian tunnels for conservation.

LESBARRERES D., FOWLER M S, PAGANO A & T. LODÉ 2010. Recovery of anuran diversity following habitat replacement, J Applied Ecol, ss presse

LODÉ T. 2009. For a few males more: do changes in sex ratio predict reproductive success and offspring survival? Evolutionary Ecology Research 11, 1-13.

JOHANET A, SECONDI J, PAYS O, PAGANO A, LODÉ T. & LEMAIRE C 2009. A case of reproductive character displacement in female palmate newts (Lissotriton helveticus). C. R. Biologies, 332: 548-557

Lodé T 2009 Mating strategies and monogamy in a territorial breeding anuran : a result of sexual conflict ? Alytes 27:37-48

LESBARRERES D., LODÉ T & J. MERILA. 2008. Male breeding success is predicted by call frequency in a territorial species, the agile frog (Rana dalmatina). Canadian Journal of Zoology 86, 1273-1279

LESBARRERESD., C.R. PRIMMER, T. LODE & J. MERILA. 2006. The effects of 20 years of highway presence on the genetic structure of Rana dalmatina populations. Ecoscience 14 : 311-323

LODÉ T., HOLVECK M.J. & LESBARRERES, D 2005. Asynchronous arrival pattern, operational sex ratio and occurrence of multiple paternities in a territorial breeding anuran Rana dalmatina. Biological Journal of the Linnaean Society. 86: 191-200

LODÉ T., HOLVECK M.J., LESBARRERES, D & PAGANO A. 2004. Sex-biased predation by polecats influences the mating system of frogs. Proceedings of the Royal Society of London, (suppl.), Biology Letters : 271 (S6): S399-S401

LODÉ T& LESBARRÈRES D. 2004. Multiple paternity in Rana dalmatina, a monogamous territorial breeding Anuran Naturwissenschaften.91: 44-47

LESBARRERES, D.,LODÉ T. & MERILA J. 2004. What type of Amphibian tunnel could reduce road kills ? Oryx 38: 220-223 .

LESBARRÈRES, D., FOWLER M., LODÉ T., PAGANO, A. 2004. Pond restoration for amphibians: how to combine highway construction and conservation biology? 18th Annual Meeting of the Society for Conservation Biology, New York, USA

SECONDI J, HAERTY W, LODE T. 2004. Is there alternate male sexual strategies in  the Palmate newt Triturus helveticus? International Society of Behavioural Ecology 2004, Jyväskulä Finland

LODÉ T. 2004. Le Putois et la sexualité des Grenouilles Agiles. Pour la Science 321: 24

LESBARRERES, D. PAGANO A.& LODÉ T. 2003. Inbreeding and road effect zone in a Ranidae : The case of agile frog (Rana dalmatina Bonaparte, 1840). C.R. Biologies, 326: S68-S72

HOLVECK MJ, DUMONT-DAYOT E & LODÉ T. 2003 Adult sex ratio and corrected effective population size in amphibian conservation. C.R. Biologies 326: 219.

LESBARRERES D. & LODE T.2002. Influence de facteurs environnementaux sur la reproduction de Rana dalmatina : implications pour sa conservation. Bulletin de la Société Herpétologique de France 104 : 62-71

LESBARRÈRES D; & LODÉ T. 2002 Variations in male calls and response to unfamiliar advertisement call in a territorial breeding anuran, Rana dalmatina: evidence for a dear enemy effect. Ethology Ecology & Evolution 14: 287-295

LODÉ T. 2000 - Effect of a motorway on mortality and isolation of wildlife populations. Ambio 29: 163-166

LESBARRERES D. & LODE T. 2000 - La conservation des amphibiens: exemple d'aménagements autoroutiers. Bulletin de la Société des Sciences Naturelles de l'Ouest de la France, 22(1) : 37-48.

GROSSELET O. & LODÉ T. 1997 - Impact des aménagements autoroutiers sur les amphibiens : l'exemple des caniveaux d'évacuation des eaux. Bulletin de la Société Herpétologique de France 81 : 5-9.

LODÉ T. 1996 - Polecat predation on frogs and toads at breeding sites in western France. Ethology, Ecology, Evolution 8 : 115-124.

LODÉ T. 1996 - Une méthode pour le suivi des déplacements des Amphibiens et des Reptiles. Bulletin de la Société Herpétologique de France 77 : 23-30.

LODÉ T. 1993 - Rythme d'activité et déplacements chez la Grenouille agile Rana dalmatina Bonaparte 1840. Bulletin Société Herpétologique de France 67-68 : 13-22.

LODÉ T. 1989 - Impact des infrastructures linéaires : Vertébrés victimes de collisions routières. Bull. Erminea 10: 1-5.

-