The role of ontogenetic allometry and non-allometric flower shape variation in species-level adaptive diversification ? Calceolaria polyrhiza (Calceolariaceae) as a case study.

STRELIN, M.; COSACOV, A.; CHALCOFF, V.; MAUBECIN, C.C.; SÉRSIC, A.N.; BENITEZ-VIEYRA, S.

EVOLUTION & DEVELOPMENT

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2020

1520-541X

Organism shape changes predictably during ontogeny, resulting in specific patterns of ontogenetic allometry. In several plant and animal lineages, among-species variation in the shape of mature organisms mirrors variation along their growth trajectories. Hence, ontogenetic allometry is an important bias in evolution. This bias should be stronger at reduced evolutionary time scales, in which among-trait correlations had less time to evolve. In this light, it was shown that adaptation was frequently facilitated by shape variation that is correlated with size along growth trajectories (allometric variation in shape, AVSh). Nevertheless, only a moderate fraction of shape variation is correlated with size during ontogeny. Hence, nonallometric variation in shape (NAVSh) should also contribute to adaptation. While NAVSh contributed to adaptation in some animal lineages, whether this is also the case for flowering plants needs further exploration. We explored the contributions of AVSh, NAVSh, and size variation to adaptive evolution in the Angiosperm species Calceolaria polyrhiza. This species strongly relies on oil-collecting bees for pollination and experienced transitions in the size of pollinators during the last 2 Ma. Using geometric morphometric we described corolla morphology in several populations across its distribution range. Variation in corolla shape was decomposed into allometric and a nonallometric components, and corolla size was estimated. We then looked for the correlation between these aspects of morphology and the pollinator. Our results suggest that adaptation mainly relied on heterochronic and heterometric NAVSh. We conclude that NAVSh can contribute to adaptation in flowering plants, even at species-level.