Abstract
Species formation during adaptive radiation often occurs in the context of a changing environment. The establishment and arrangement of populations, in space and time, sets up ecological and genetic processes that dictate the rate and pattern of differentiation. Here, we focus on how a dynamic habitat can affect genetic structure, and ultimately, differentiation among populations. We make use of the chronology and geographical history provided by the Hawaiian archipelago to examine the initial stages of population establishment and genetic divergence. We use data from a set of 6 spider lineages that differ in habitat affinities, some preferring low elevation habitats with a longer history of connection, others being more specialized for high elevation and/or wet forest, some with more general habitat affinities. We show that habitat preferences associated with lineages are important in ecological and genetic structuring. Lineages that have more restricted habitat preferences are subject to repeated episodes of isolation and fragmentation as a result of lava flows and vegetation succession. The initial dynamic set up by the landscape translates over time into discrete lineages. Further work is needed to understand how genetic changes interact with a changing set of ecological interactions amongst a shifting mosaic of landscapes to achieve species formation.
Highlights
The structuring of populations is critical to an understanding of the process of speciation
We focus on how a dynamic habitat can affect genetic structure, and differentiation among populations
We make use of the chronology and geographical history provided by the Hawaiian archipelago to examine the initial stages of population establishment and genetic divergence
Summary
The structuring of populations is critical to an understanding of the process of speciation. The establishment of small populations, and fragmentation of larger ones, is arguably the most important aspect in the initiation of species divergence and adaptive radiation, research has progressed along two largely independent avenues—genetic and ecological. The former builds on ideas of founder effects (Carson and Templeton 1984) and metapopulation dynamics (Gavrilets et al 2000), the latter on species-area relationships (Losos and Schluter 2000) and food web theory (Schoener and Spiller 2010). We focus on population genetic aspects of diversification, but incorporate discussion of the ecological context
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