SUMMARY of the ISBE Post-Conference Symposium: The role of behaviour in non-ecological and non-adaptive speciation

# by Maren Wellenreuther

On the 18th of August, we organized the Symposium 'the role of behaviour in non-ecological and non-adaptive speciation'. Invited speakers were John Wiens (Stony Brook University, USA), Rampal Etienne (University of Groningen, Netherlands) and Kerry Shaw (Cornell University, USA). We also had several contributed talks on diverse topics which filled the day from 9:00-17:30. Funding for this symposium was provided by the European Science Foundation (ESF) and the Research Networking Programme on Frontiers of Speciation Research (”FroSpects”).


John Wiens (Ecology and Evolution/Stony Brook University). Email:
Niche conservatism, ecology, and speciation
In recent years, there has been increasing interest in the role that ecology may play in speciation.  Ever since Darwin, it is typically assumed that this role involves ecological divergence between incipient species in different environments.  While this scenario is becoming increasingly well-supported, it may not be the only role of ecology in speciation, nor even though most common.  Among the geographic modes of speciation, allopatric speciation generally seems to be the most common.  I argue that the maintenance of ecological similarity over time (niche conservatism) may be a key aspect of allopatric speciation.  From first principles, a geographic barrier consisting of unsuitable ecological conditions may be necessary to geographically split an ancestral species into two allopatric populations, and this scenario requires that populations be unable to adapt to those ecological conditions quickly enough to maintain populations and gene flow across the barrier.  Therefore niche conservatism, rather than adaptation to divergent ecological conditions, should often be an essential part of allopatric speciation, even if niche divergence occurs later in the speciation process.  In this talk, I will summarize this basic model and review recent work from my lab testing this idea, both with empirical data and simulations.  We now have strong evidence for speciation through climatic niche conservatism in some cases (but with many counterexamples), and new theoretical and empirical results show when this should be expected to occur.  Behavioral habitat selection may play a critical role in speciation through niche conservatism, but this remains poorly explored.

Rampal S. Etienne, (Community and Conservation Ecology Group, University of Groningen).
The consequences of protracted speciation

Many models of macro-evolution or community evolution assume, for simplicity, that speciation takes place instantaneously. However, except for exceptional cases such as speciation by chromosome doubling, speciation takes time. In this presentation I will discuss the consequences of the mere fact that speciation takes time, for species distributions and phylogenetic patterns.

Kerry Shaw (Department of Neurobiology and Behavior, Cornell University).
The struggle for mates versus the struggle for existence:  speciation and the role of divergence in mate signaling systems

Rapidly multiplying lineages wherein a single ancestor diversifies ecologically and phenotypically into a species flock of many species is known as an adaptive radiation. Ecological speciation, mediated by divergent natural selection, is an hypothesized mechanism that produces this diversity, notably with the outcome that sister species are adaptively distinct from each other. A commonly held corollary of an adaptive radiation is that the phenotypic changes that distinguish sister species elevate the capacity to utilize particular environments. In this talk, I confront the question of what it means for species to be adaptively distinct. I also ask whether adaptively distinct species routinely show, or do not show, other phenotypic distinctions, such as mating behavior, and consider the potential causes of common patterns. Non adaptive radiation, by definition, is the rapid multiplication of species without accompanying differentiation in ecology or increased capacity to utilize a particular environment. I present a sexual selection mechanism that could be quite common in producing species that are not adaptively distinct, cf. those resulting from an adaptive radiation. With regard to possible mechanisms of speciation that fuel radiations, I point out a potential imbalance between speciation mechanisms commonly under study. Non-ecological speciation mechanisms may play a role in both adaptive and non-adaptive radiations whereas ecological speciation mechanisms are confined to a role in adaptive radiation only.