Signals of the condition of individuals directly influence individual fitness through variation in the fitness of chosen mates. They are also targets of sexual selection as females choose males based on variation in traits that may, or may not, be honest signals of male condition.
Plants with populations on both serpentine and non-serpentine soils offer an opportunity to study the competing effects of selection and gene flow on adaptation and genomic variation, diversification and homogenization.
PI: Peter B. Pearman
Collaborators: Noelia Hidalgo Triana, Andrés V. Pérez, Teresa Navarro de Águila, University of Malaga
Doctoral Student: Pablo Arrufat
Serpentine soil presents a difficult edaphic environment for most plants for several reasons. These soils have high concentrations of a variety of heavy metals, a low calcium to magnesium ratio, and tend to have low water content. These environmental factors have been shown to drive local adaptation to soil in a variety of studies. In the hills near Malaga, Spain, serpentine outcrops are common and interspersed with areas of non-serpentine soil. Despite the selective pressure that surely exists for specialization to serpentine environments, a number of plant species have populations on both serpentine and non-serpentine soils, sometimes within sight of each other. This suggests that there may be strong, contrasting selection among nearly adjacent populations. This is of interest because adaptation to serpentine has been shown to entail costs, with serpentine genotypes being less able competitors when they occur in non-serpentine environments in reciprocal transplant experiments.
We are developing research that examines the interacting effects of selection and gene flow in several serpentine species, in order to get a broad picture of the response of populations in these communities. Serpentine and other ultramafic and peridotitic soil is widely distributed in the Sierra Bermeja, not far from the southern Spanish city of Malaga. We are curious whether gene flow is similar in populations of species that share this heterogeneous environment, and whether any barriers to gene flow are equally effective in the different species. Some of the species have different subspecies that are typical of one soil or the other, while other species have no recognized morphological differences among populations on different soil types. We are working with local botanists from Malaga, and we hope to systematically expand our preliminary collections once the pandemic has subsided. We will then construct ddRADseq libraries at the UPV and contract their sequencing, then probe the data to determine the influences of both gene flow and selection across plant genomes.
This project seeks to understand historical demography, phylogeography and environmental adaptation in a widespread North American shrub.