Brown adipose tissue: physiological function and evolutionary significance

Area of Science:

• Evolutionary biology
• Mammalian physiology
• Thermogenesis

Background:

• Brown adipose tissue (BAT) is a specialized thermogenic organ in eutherian mammals, essential for adaptive non-shivering thermogenesis (NST).
• Uncoupling protein 1 (UCP1) in BAT mitochondria dissipates proton motive force as heat, a function that evolved later than UCP1 orthologues themselves.
• Recent research on BAT in metatherians and afrotherian eutherians, like the tenrec, provides new perspectives on the evolution of mammalian NST and endothermy.

Purpose of the Study:

• To review the physiological function and distribution of BAT.
• To explore the evolutionary context of BAT and NST.
• To highlight recent findings on BAT in diverse mammalian clades.

Main Methods:

• Literature review of recent studies on BAT.
• Comparative analysis of BAT distribution and function across mammalian phylogenies.
• Focus on afrotherian species, including the lesser hedgehog tenrec.

Main Results:

• BAT's role in NST is a key feature of modern eutherian mammals.
• The evolution of UCP1's thermogenic significance occurred after the divergence of fish and mammals.
• Studies on tenrecs suggest a link between BAT and the emergence of eutherian endothermy.

Conclusions:

• BAT plays a critical role in adaptive thermogenesis in mammals.
• The evolutionary trajectory of BAT and NST is linked to mammalian diversification and endothermy.
• Further research on phylogenetically distinct species is crucial for understanding BAT evolution.