How toothed whales divide up the world: phylogeny and ecology shape life-history strategies of odontocetes.

Abstract

Background: Understanding the evolution of life-history strategies within a taxonomic guild offers critical insights into how species allocate energy toward growth, reproduction, and survival in response to environmental pressures. We examined 42 odontocete whale species using six key life-history traits and three major environmental variables- latitude, bathymetry, and sea ice -to identify broad patterns in ecological and evolutionary strategies.

Results: While controlling for body size and phylogenetic relatedness, we used archetypal clustering analysis to identify three groups of species according to shared life-history characteristics: bet-hedging, slow, and fast. We then assessed environmental associations among these three life-history strategies. Ancestral state reconstruction was used to disentangle the roles of phylogenetic constraint and ecological adaptation in shaping these strategies. Our results reveal convergence in life-history traits among distantly related species occupying deep, offshore habitats, suggesting that environmental similarity can drive parallel evolutionary outcomes. In contrast, species inhabiting more ephemeral, high-latitude environments with seasonal sea ice exhibit lineage-specific adaptations, reflecting a stronger influence of evolutionary history.

Conclusions: These findings offer a framework for tailoring conservation strategies to the distinct ecological profiles of odontocete groups, accounting for factors such as exposure to anthropogenic stressors, reliance on specialized habitats, and inherently slow recovery rates following human exploitation.