• Marine endotherms (birds and mammals) exhibit slower life histories (delayed maturity, longer lifespans, reduced fecundity) compared to their terrestrial counterparts due to the challenges of marine environments.
• The study indicates that these slow life histories are adaptive convergences, driven by the need for enhanced energy acquisition and storage in marine environments where resources are often scarce and unpredictable.
• Ancestral traits, such as a pre-existing slow pace-of-life in aquatic ancestors, likely facilitated the successful colonization of marine environments and the evolution of even slower life histories.

A study published in Nature Communications explores the evolutionary adaptations of endotherms (birds and mammals) that have transitioned to marine environments. The research focuses on how these animals have developed slower life histories, characterized by delayed maturity, longer lifespans, and reduced fecundity. This is attributed to the unique challenges of marine life, including dispersed and unpredictable food resources. The study uses phylogenetic comparative analyses to reconstruct evolutionary transitions and model life history evolution, providing insights into the ecological and adaptive factors driving these changes.

• What: Marine endotherms (birds and mammals) have evolved slower life histories (delayed maturity, longer lifespans, reduced fecundity) as an adaptation to the challenging marine environment, characterized by scarce and unpredictable food resources.
• Who: The study focuses on marine endotherms, specifically birds (Aequorlithornithes and Anseriformes) and mammals (Cetartiodactyla, Carnivora, and Sirenia). Key researchers include Daniel Sol, Antón Prego, Laura Olivé, Meritxell Genovart, Daniel Oro, and Antonio Hernández-Matías.
• When: The study was published on 08 May 2025. The research involved analyzing evolutionary transitions and life history traits of marine endotherms over extended evolutionary timescales.
• Where: The research was conducted by scientists at the Institute of Evolutionary Biology (CSIC-UPF), Barcelona, Catalonia, Spain; Centre for Ecological Research and Applied Forestries, Cerdanyola del Vallès, Catalonia, Spain; and other institutions in Barcelona and Girona, Spain. The study has global implications, considering marine endotherms across various oceanic regions.

The study provides a comprehensive analysis of the evolutionary pressures shaping the life histories of marine endotherms. By employing phylogenetic comparative methods, the researchers demonstrate that the transition from terrestrial or aquatic environments to marine environments is associated with a shift towards slower life histories. This shift is likely driven by the need to adapt to challenging conditions such as dispersed food resources and the energetic demands of marine life. The research also highlights the importance of ancestral traits and ecological lifestyles in understanding the evolution of these slow-paced strategies. The findings contribute to a broader understanding of life history theory, emphasizing the significance of ecological context in shaping evolutionary trajectories.

The study concludes that the evolution of slow-paced life histories in marine endotherms is an adaptive response to the unique challenges of marine environments. This adaptation involves a trade-off between reproduction and survival, with marine endotherms investing in longer lifespans and delayed maturity at the expense of reduced fecundity. The findings underscore the importance of considering ecological lifestyle and ancestral legacies in understanding the evolution of life history strategies. The study also highlights the vulnerability of marine endotherms to human-induced threats, given their slow life histories and limited capacity for rapid adaptation.