Résumé
Violation of the molecular clock has been amply documented, and is now
routinely taken into account by molecular dating methods. Comparative
analyses have revealed a systematic component in rate variation, relating
it to the evolution of life-history traits, such as body size or
generation time. Life-history evolution can be reconstructed using
Brownian models. However, the resulting estimates are typically uncertain,
and potentially sensitive to the underlying assumptions. As a way of
obtaining more accurate ancestral trait and divergence time
reconstructions, correlations between life-history traits and substitution
rates could be used as an additional source of information. In this
direction, a Bayesian framework for jointly reconstructing rates, traits,
and dates was previously introduced. Here, we apply this model to a 17
protein-coding gene alignment for 73 placental taxa. Our analysis
indicates that the coupling between molecules and life history can lead to
a reevaluation of ancestral life-history profiles, in particular for
groups displaying convergent evolution in body size. However,
reconstructions are sensitive to fossil calibrations and to the Brownian
assumption. Altogether, our analysis suggests that further integrating
inference of rates and traits might be particularly useful for
neontological macroevolutionary comparative studies.