Larger offspring associated with lower temperatures across species of Microporella, a widespread colonial invertebrate

Among life history traits, offspring size has one of the most direct impacts on fitness, influencing growth, recruitment and survival individual, therefore affecting population, ultimately macroevolutionary outcomes. Despite its ecological evolutionary importance, little is known about how varies in lineages over timescales, especially for colonial organisms. Here, we use cheilostome bryozoan genus Microporella to investigate variation lineage. The species-rich, cosmopolitan, a calcified skeleton (and hence readily preserved fossil record), brooder. brood structure (ovicell) reliably reflects space occupied by larva ovicell good proxy size. Using suite biotic abiotic factors, ask what best explains offspring/larval contemporary species , changes through millions years We find that affected combination module water temperature (or latitude when are included), while fecundity levels nutrients have weak no effect this trait. species, descendant statistically more likely larger than their putative ancestors, with difference between pairs explained temporal latitudinal shifts. Our results suggest both controls historical considerations important understanding trait evolution.