Ecological and Evolutionary Factors Shape the Extra‐Tropical Latitudinal Species Diversity Peak in Procellariiform Seabirds

Aim Latitudinal diversity gradients are common across broad taxonomic groups, with most exhibiting peak species richness in the tropics. These have often been explained by greater primary productivity and diversification rates in the tropics. However, some taxa show peak species richness outside the tropics, providing valuable contrasts for improving our understanding of the factors driving latitudinal diversity gradients. In this study, we tested ecological and evolutionary predictors of latitudinal diversity in Procellariiform seabirds, which exhibit peak species richness at temperate Southern Hemisphere latitudes. Location Global. Time Period Paleogene to present. Major Taxa Studied Order Procellariformes (Seabirds). Methods We assessed the latitudinal diversity gradient for Procellariiformes in the context of ecological factors including ocean productivity, ocean area, wind speed, and number of coastlines for breeding. We simultaneously tested evolutionary factors comprising lineage ages and transition and diversification rates among latitudes. Results While most ecological factors were retained in a Generalised Additive Model, wind appeared positively and most closely related to latitudinal breeding species richness. There was no evidence that unequal evolutionary transitions or diversification explained the latitudinal diversity gradient. However, an approximately two‐fold earlier origin in the Southern Temperate zone likely provided more time for species accumulation there. Main Conclusion Wind and time since evolutionary origin best explain the extratropical peak in breeding species richness of Procellariiform seabirds, emphasising the importance of integrating ecological and evolutionary perspectives when investigating latitudinal diversity gradients. Additionally, our study also illustrates how quantification of species distributions and the choice of phylogeny when testing evolutionary predictors can influence interpretations of latitudinal diversity gradients.