|Estimation of connectivity in marine biological networks: graph theory versus metapopulation models. An application to the Gulf of Lion |
Conference: ASLO 2015 (Granada, ES, 2015-02-27)
Ref HAL: hal-01208436_v1
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Different methods have been proposed for assessing important emerging properties for species conservation induced by biological networks connectivity. Graph theory has recently been used to investigate species persistence conditions from different measures of connectivity in this kind of networks. In this study, for the first time,we compare a set of metrics defined in graph theory to a metapopulation modelling approach. These approaches are confronted to evaluate the persistence of soft bottom polycheates populations in the Gulf of Lion,relying on the same connectivity matrices derived from larval dispersal simulations. Various classical graph analysis methods are tested while new descriptors are derived and evaluated. Most outstanding input of this work is the introduction of a novel metric for measuring the distance between nodes in a graph in order to correct an overlooked difficulty in previous literature, when dealing with connectivity matrices containing larval transfer probabilities. This metric ensures a physically meaningful interpretation of shortest paths and consequently betweenness. The comparison with metapopulation model enables to single out the interpretation for species persistence of the graph descriptors.Graph theory complements the results of the metapopulation model by adding an exhaustive analysis of the spatial information. In particular,modularity and bridging centrality are shown to quantify clusters of strongly interconnected nodes (communities) and to distinguish the rescuing sites and the sink sites. The sites bringing species' regional persistence seem better indicated by bridging centrality and shortest cycles lengths.