METAPOP – Spatial structure of amphibian (meta)populations in Mediterranean farmland landscapes: conservation implications

Metapopulation theory is a central paradigm in conservation biology, providing a conceptual framework to predict the likelihood of species persistence in fragmented habitats. Although this framework has been widely used in conservation studies, it is unclear whether its critical assumptions are warranted for most real populations. This is a case in point for amphibians, which are often assumed to occur in metapopulations, though there is limited evidence on their spatial population organization. Clearly, further empirical information is needed on the spatial organization of real populations, if the metapopulation concept is to be useful in practice for the conservation management of species inhabiting patchy habitats. This project will address this issue using ecological and genetic tools, analysing the spatial structure of pond-breeding amphibians in Mediterranean farmland. The study will be carried out in Southwest Portugal, where past information is available on amphibians distributions and abundance (1997 and 2002), and on past and present farming regimes. Specifically, the project will evaluate whether populations of the most common amphibian species may be regarded as metapopulations or single panmitic populations.  

Three main forms of metapopulation structure will be analysed, namely (i) classical metapopulations, (ii) nonequilibrium metapopulations and (iii) source-sink metapopulations.  For species showing metapopulation structure, metapopulation models will be developed, in order to predict the likelihood of species persistence under different scenarios of agricultural land planning. 

The project will be based on six tasks: (i) Identification and characterization of amphibian breeding habitats; (ii) Estimation of amphibian breeding habitat losses and fragmentation; (iii) Characterization of amphibian distributional dynamics; (iv) Estimation of amphibian population declines; (v) Microsatellite analysis of subpopulation isolation and migration patterns; and (vi) Modelling of metapopulation persistence in an agricultural landscape. The first five tasks will allow the identification of the most plausible metapopulation structure for each species, whereas the last task will integrate the available information, providing a quantitative description of metapopulation organization and dynamics. The study provides novel scientific information on the metapopulation ecology of amphibians, because: i) there is little information on amphibian dynamics in Mediterranean farmland, and the factors underlying it; ii) few studies have combined ecological and genetic tools for evaluating the spatial organization of amphibian (meta)populations; iii) little is known about the landscape scale impacts of agriculture intensification on amphibians; iv) there have been few attempts to assess the viability of amphibian metapopulations under contrasting land planning scenarios. The work has also applied implications, providing information to the conservation management of amphibians and for planning environmentally friendly agricultural landscapes.