Diversity begets diversity...in white sands?

Thanks for the introduction Simone!

This is Kayla signing on, and I’d like to address some of the questions Simone brought up at the end of her last entry. Specifically, I want to talk about the idea that diversity begets diversity. Schluter introduces this idea, which was first suggested by Whittaker, in chapter four of his book. Basically Whittaker proposed the idea that the addition of new species to an area, through colonization or evolution, constitutes an addition of new resources to an area which other species in higher trophic levels can take advantage of. The increase in resources permits new predator species to evolve or colonize the area, which in turn decrease the numbers of prey species and allows for the introduction of new prey species…and so on.

This idea could be relevant to an increase in species diversity in white sands. Currently there are three lizard species inhabiting the area, and we are only aware of a few avian predators having much of an effect on their populations. The presence of the lizards could encourage the introduction of new predator species to the area; these species could reduce the population sizes of the three lizard species and create additional ecological opportunity for colonization or evolution of new lizards in the area.

But could this kind of predator-prey interaction lead to an adaptive radiation? Simone mentioned the fact that some classic adaptive radiations seem to have come to be through multiple colonization events. This type of interaction seems like it could increase the chances of multiple colonization events, or even encourage the evolution of new species in white sands.

Though the idea that diversity begets diversity may apply to white sands, there is still the problem of gene flow to think about. As Simone mentioned, the environment is dynamic with few physical barriers. The predator-prey interaction envisioned by Whittaker would not decrease the chances of gene flow in this system. Gene flow is likely a major obstacle to speciation of white sands lizards, but as we continue to read Schluter, maybe we can to gain more insight into this and the other questions Simone posed at the end of her entry. Tune in next week to find out!