The evolution of gestation length in eutherian mammals

Area of Science:

• Evolutionary biology
• Comparative genomics
• Mammalian evolution

Background:

• Eutherian mammals display significant variation in gestation length.
• Gestation length is traditionally linked to body mass and lifespan.
• Understanding evolutionary changes in these associations is crucial.

Purpose of the Study:

• To investigate how gestation length variation, and its association with body mass and lifespan, has evolved across mammals.
• To identify evolutionary shifts in these trait relationships.

Main Methods:

• Phylogeny-informed analyses were performed on 845 extant eutherian species.
• Comparative analyses assessed associations between gestation length, body mass, and lifespan.
• Evolutionary shifts in trait variation were identified across the mammalian phylogeny.

Main Results:

• Associations between gestation length, body mass, and lifespan varied considerably across mammalian clades.
• No association was found in Chiroptera (bats) and Cetacea (whales).
• Significant evolutionary shifts in trait associations were identified, with some linked to environmental transitions (e.g., marine adaptation, flight).

Conclusions:

• The relationship between gestation length, body mass, and lifespan is not static but has evolved dynamically across mammalian history.
• Major evolutionary events, such as adaptation to new environments, have influenced these trait associations.
• Gestation length variation is a key indicator of broader evolutionary patterns in mammals.