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Spatial Analysis of Biological Variation

Evolutionary Biology: Charles Ross (Hampshire College)

Evolutionary and ecological processes (selection, assortative mating, etc) often must be inferred from patterns of variation in nature. These patterns may vary in time and space, and they may vary within vs. between groups. Additionally, the relationship among different kinds of variation (genetic vs geographic vs. ecological) may provide useful insight. Unfortunately, the same pattern may point to different potential explanations, different patterns may point to the same explanation, or the patterns of variation may not fit any current explanation. Consequently, an ongoing challenge is to develop models that may link evolutionary and ecological processes to patterns of variation in actual biological systems. Spatial analysis of variation in biological systems currently is an especially active area or research (landscape genetics, for example).

Hybrid zones, spatial areas where two distinct groups (eg. species) produce hybrid offspring, may be considered a special case of spatial variation. Hybrid zones have great advantages for understanding evolutionary forces because of the particular nature of their structure: linking hybrid zone structure (pattern) and maintenance (process) can reveal how evolution leads to adaptation and how speciation works. Currently, hybrid zone models focus on simple, one-dimensional zones, but even these are limited. Two perspectives of investigation are needed. First, exploring models of hybrid zone structure as a function of dimensionality, complexity, scale, and heterogeneity of the system, are interesting and productive directions. Second, testing candidate models with biological data will provide insight into the connection between spatial patterns and evolutionary parameters.