It is critical to study factors that are important for origin and maintenance of biological
diversity. A comparative approach involving a large number of populations is
particularly useful.We use this approach to study the relationship between ecological
factors and phenotypic diversity in Icelandic Arctic charr (Salvelinus alpinus).
Numerous populations of small benthic charr have evolved in lava springs in Iceland.
These charr appear morphologically similar, but differ in important morphological
features related to feeding. We found a clear relationship between diversity in
morphology, diet, and ecological factors among populations. In particular, there
were clear differences in morphology and diet between fish coming from habitats
where the lava spring flowed on as a stream compared to habitats where the lava
spring flowed into a pond. Our study shows that ecological factors are important
for the origin and maintenance of biological diversity. The relationship between
phenotype and ecological factors are observed on a fine scale, when comparing numerous
populations that are phenotypically similar. This strongly suggests that for
understanding,managing, and conserving biological diversity important ecological
variables have to be taken into the account.Keywords: Adaptation, Morphometrics, Natural selection, Diet, Phenotypic plasticit
