Speaker: Dr Martino Malerba from Monash University (Melbourne, Australia)
Place: Forum Chriesbach, FC-C24

Phenotypic correlations between body size and life-history traits have long fascinated biologists, yet the causal links are often elusive due to many confounding variables (e.g. taxonomy, environment, age, body condition). As a novel and more direct test, we used artificial selection to evolve the single-celled green microalga Dunaliella teriolecta (Chlorophyta) toward different mean body sizes. Then, we quantified the effects of size on multiple traits of the size-evolved lineages. Within 350 generations of artificial selection (c. 24 months), we generated a 1500% difference in cell volume among selected lineages, resulting in profound differences in most measured traits of this species, such as photosynthetic characteristics, sinking rates, swimming ability, predation risk and growth performance. In this talk, I will explain costs and benefits of different body sizes. Overall, the evidence suggests that the current size of a species is the product of context-dependent selection pressures in nature.

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