Testing adaptive and non-adaptive radiations and biodiversity in supernetworks

Background/Question/Methods

Empirical and theoretical studies on the origins of radiations have shown the role of genetic, sexual, ecological and geographical processes. Most empirical data suggest ecological speciation driven by adaptations to niches as the dominant force triggering radiations. There is, however, still a lack of theory (1) inferring, in the same framework, the effects of the mechanisms driving radiations to macroecological diversity patterns, (2) predicting the large variation in occurrence and extent of radiations between taxa and between localities of the same taxon, and (3) identifying whether this variation comes from genetic, sexual or ecological mechanisms or some combination of these processes.  In the present talk we aim to (1) introduce individual and DNA sequence-based eco-evolutionary models of interacting networks (i.e., mating and spatial graphs or mating graphs and trophic food webs) to generate patterns of diversity and (2) compare our model with genetic, sexual, ecological and geographical mechanisms using two of the largest individual-based food webs to date: (1) The Guadalquivir estuary food web, southern Spain, with 100,000+ individuals sampled in different environmental conditions, and  (2) the biodiversity inventory from the "Area de Conservacion Guanacaste" in northwest Costa Rica with 450,000+ individual caterpillars, their parasites and host plants collected since 1978. These two datasets also have independent estimations of abundance and present sufficient levels of resolution and number of species to permit inference at individual, species and community levels simultaneously.

Results/Conclusions

Our model uncovered higher than expected diversity of abundant species in both datasets but predictions for other ranges of the species diversity curve fit the data. These results suggest that in addition to adaptive processes like negative frequency-dependent selection driving niche diversification, non-adaptive processes like sexual selection, mutation, and genetic-ecological drift may be playing an important role in structuring interacting networks and generating and maintaining diversity.