Community level approach to understanding speciation in Hawaiian lineages


I am also involved in a second project, a Dimensions of Biodiversity NSF grant called “Community level approach to understanding speciation in Hawaiian lineages”. This grant is based at UC Berkeley. Our goal is to synthesize ecological and evolutionary perspectives to analyze processes that drive emergent patterns of island biodiversity.

Traditionally, ecological and evolutionary analytical perspectives have developed separately in part because Ecology and Evolution have progressed as independent biological disciplines without much integration. The lack of integration between these two disciplines is more notable at the community level. On the one hand, the ecological perspective focuses on the causes of species extinction that hazard the biodiversity of a specific place. Ecological processes include those that drive the population dynamics of the species (e.g. birth, death, immigration and emigration rates), the behavior of the organisms, and the interactions among the different species in an ecosystem. On the other hand, the evolutionary perspective focuses on the generation of new species, the emergence of new traits in a species across generations, and adaptation to environmental changes.

Why the archipelago of Hawaii?


The archipelago of Hawaii is a good system to study the interplay between ecological and evolutionary processes at the community level, because the islands exhibit a clear gradient of isolation from the youngest (close to the mainland) to the oldest (far away from other islands and the mainland). Ecological processes may be more important in structuring the biological communities of the youngest islands, because the proximity to the mainland leads a predominance of migrations, and their short existence did not give enough time for speciation to occur. Conversely, evolutionary processes may be more relevant in structuring the oldest islands, since they are too isolated for receiving migrants and they have been in the planet long enough for allowing high levels of speciation.

My role in this project is to integrate the ecological and evolutionary perspectives by using the methods and concepts of ecological networks. We are developing models of ecological networks integrating evolutionary and ecological dynamics. I am also helping the taxonomic specialists of the project to construct the food web for each island from the species lists that they are expert on. We will contrast the network structures that result from the model (assuming different levels of migration and speciation rates) against the structure of the empirical networks that are observed in the different islands of Hawaii.  In that way, we will be able to test our hypothesis of young island communities driven mostly by ecological processes while old island communities driven by evolutionary processes.

Understanding the processes behind the generation and maintenance of biodiversity will help us to counter the tremendous loss of biodiversity caused by the high rates of species extinctions produced by environmental problems of global warming, pollution, biotic invasions, etc.