The evolution of gestation length in eutherian mammals

Area of Science:

• Evolutionary biology
• Reproductive biology
• Mammalogy

Background:

• Gestation length, the duration of pregnancy, is a key aspect of mammalian reproduction.
• Eutherian mammals display wide variation in gestation length, often linked to body mass and lifespan.
• Evolutionary changes in gestation length and its associations with other life history traits are not well understood.

Approach:

• Phylogeny-informed analyses were conducted on 845 extant eutherian mammal species.
• Examined how gestation length variation associates with body mass and lifespan across mammalian clades.
• Identified adaptive shifts in gestation length variation throughout mammalian evolution.

Key Points:

• Gestation length associations with body mass and lifespan vary considerably across mammalian clades.
• Chiroptera and Cetacea showed no association with lifespan or body mass, while Carnivora linked only to body mass.
• 52 adaptive shifts in gestation length variation were identified, with six common shifts when considering body mass and lifespan.

Conclusions:

• Evolutionary constraints on gestation length have varied significantly across mammalian phylogeny.
• Divergent evolutionary dynamics suggest distinct genetic architectures for gestation length in different mammal clades.
• Marine transitions in Cetacea and Pinnipedia coincided with adaptive shifts in gestation length.