Evolutionary versus ecological success in Antarctic benthic invertebrates

The unusually high proportion of brooding compared with broadcaster species among coastal Antarctic invertebrates has been traditionally interpreted as an adaptation to local environmental conditions. However, species with a planktotrophic developmental mode are ecologically dominant (in terms of abundance of individuals) along Antarctic coastal areas. Therefore, is the apparent ecological success of broadcasters related to their developmental mode? We argue that the present shallow Antarctic benthic invertebrate fauna is the result of two processes acting at different temporal scales. First, the high proportion of brooding species compared with coastal communities elsewhere corresponds to species-level selection occurring over geological and evolutionary times. Second, the ecological dominance of broadcasters is the result of processes operating at ecological timescales that are associated with the advantage of having pelagic larvae under highly disturbed conditions.