Larval brooding correlated with high early origination rates in cheilostome Bryozoa

Life-history traits such as dispersal affect population attributes like
gene flow, which can have consequences for speciation and extinction rates
over macroevolutionary timescales. Here we use the Cheilostomatida, a
monophyletic order of marine bryozoans, to test whether a life-history
trait, larval brooding, affected the origination and extinction rates of
genera throughout their fossil record. Cheilostome lineages that brood
their larvae have shorter larval dispersal distances than non-brooding
lineages, which has led to the hypothesis that the evolution of larval
brooding decreased gene flow, increased origination, and drove their
Cretaceous diversification. Brooding cheilostomes are far more diverse
than non-brooding cheilostomes today, but it remains to be shown that
brooding lineages have a higher origination rate than non-brooders. We fit
time-varying Pradel Seniority capture-mark-recapture models to look at the
effect of brooding on origination and extinction rates during the
Cretaceous cheilostome diversification, the Cretaceous-Paleogene mass
extinction and recovery, and through the Cenozoic. Our results support the
hypothesis that brooding affects origination rate, but only in the
Cenomanian to Campanian. Extinction rates do not differ between brooding
and non-brooding genera, and there is no regime shift specific to the
Cretaceous-Paleogene mass extinction. Our work illustrates the importance
of using fossil occurrences and time-varying models, which can detect
interval-specific diversification differentials.