Self-organization may play a prominent role in evolution, especially in the context of landscapes, which regulate interactions between individuals. One consequence is the evolution of cooperation in marginal and viscous habitat networks, whereas randomly interacting populations are more dominated by intraspecific competition and therefore more likely to behave selfishly.
Landscape structure influences genetic diversity and speciation. In connected landscapes, genes flow freely throughout a species and speciation is inhibited. However, in fragmented landscapes, a species breaks into isolated subpopulations. Fragmentation increases the risk of inbreeding and loss of genetic diversity in these subpopulations. Divergence between population fragments may also underlie adaptive radiations, in which many novel species suddenly emerge simultaneously.
As species adapt to their environment, they are often faced by tradeoffs in allocating resources for different purposes. These tradeoffs can lead to the evolution of distinct morphs within a species, or to speciation. For example, many mangrove species face a conflict between salt tolerance and competitive ability. Mangroves grow in estuaries, where salinity varies along the gradient between land and sea. Mangroves growing landward will be under strong selection for competitive ability, while those growing closer to the sea require better salt tolerance. The tradeoff, combined with local seed dispersal, can generate discrete banding patterns in the distribution of mangrove species, where each species is displaced by a more salt-tolerant one closer to the sea.
Contingency also plays a large part in the organization of spatial distributions. Spatial dominance occurs when a particular species is overwhelmingly abundant in a local environment. In this situation, the species can resist invasion, even by a superior competitor, because its propagules are much more numerous locally than those of any other population. For the same reason, a mutation that enables a species to exploit a novel environment may result in it permanently excluding potential competitors from that environment, even after they have evolved similar adaptations.
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