|DiverseShores - Testing associations between genetic and community diversity in European rocky shore environments|
Programme - PTDC/BIA-BIC/114526/2009
Execution dates - 2011-04-01 - 2014-03-31 (36 Months)
Funding Entity - FCT
Funding for CESAM - 137.04 €
Total Funding - 194.106 €
Proponent Institution - Universidade de Aveiro
Centro de Ciências do Mar (CCMar/CIMAR) - Universidade do Algarve
Understanding the heterogeneous distribution of biological diversity is one of the fundamental premises of ecology. Studies primarily focus on two levels of diversity: 1) genetic diversity within species or 2) species diversity within communities. Both measures are recognised as important by ecologists, but they are generally considered mutually exclusive. Studies of community diversity typically pay little attention to genetic diversity within species, while studies of genetic diversity within populations rarely consider community diversity as a whole. This is particularly the case with conservation-orientated studies that tend to focus either on community and habitat composition, or the genetic diversity of prominent species. Recently, Vellend(2003) when considering both levels of diversity simultaneously hypothesised these measures should be very closely linked. Vellend’s hypothesis was based on observations that similar processes influence both levels of diversity. Specifically, the well-established theory of island biogeography invokes a balance of colonisation and extinction for determining community diversity (MacArthur & Wilson 1967), while classic island models of population genetics invoke gene flow and genetic drift as regulating influences on genetic diversity (Wright 1940). The novel prediction from this hypothesis was termed the species-genetic diversity correlation (SGDC).
Based on data from previously published studies, together with field data from a temperate forest, Vellend (2003) demonstrated positive correlations between species and genetic diversity across ‘island’ habitats in a range of taxa. It was suggested that the SGDC may be a general macro-ecological pattern, with equal significance to the species-area, species-energy and species-latitude relationships that form the basis of our understanding of biodiversity. Additional support for the SGDC comes from a spatio-temporal field study in Borneo, results of modelling work and experimental observations (Etienne and Olff, 2004; Cleary et al., 2006). Simulations of genetic population differentiation, furthermore, showed a rapid increase of divergence over small spatial scales, but the relationship levels-out at greater distances (Palumbi 2003). This relationship even holds under scenarios of high larval dispersal, and is remarkably similar to that of community differentiation over increasing spatial scales. For example, community dissimilarity of tropical lowland plants increases rapidly over small distances, but then evens out (Condit et al. 2002). In a microcosm study, rates of changes in genetic diversity within component species were concordant with those of community diversity (Booth & Grime 2003).
So, when taken together, this evidence suggests that species and genes may indeed be subject to similar processes that affect their spatial distributions. However, field-based assessments in marine environments are completely lacking, and further evidence of the generality of the pattern is required across systems and levels of taxonomic diversity. A thorough understanding of the processes generating patterns of biological diversity is crucial for management and conservation of threatened natural resources in marine environments. We aim to test hypotheses consistent with the suggestion that similar processes result in comparable spatial distributions of community and genetic diversity at two spatial scales, firstly, along the Portuguese coast and secondly, the Mediterranean and North Atlantic. We aim to test whether: 1) local (α) community diversity is positively correlated with intraspecific (within species) genetic diversity of the constituent species; 2) between area (β) community diversity is positively correlated with gene flow between conspecific populations of constituent species; 3) both genetic diversity and community diversity depend upon environmental variables; and 4) both diversity measures respond to environmental perturbations in similar ways. This will be, to our knowledge, the first broad-scale study in a marine setting with different taxonomic groups to investigate these fundamental questions. We expect results to have broad significance for our understanding of processes contributing to formation of spatial and temporal patterns of biological diversity.