Temperature, size and developmental plasticity in birds.

Area of Science:

• Ecology
• Evolutionary Biology
• Climate Change Biology

Background:

• Rising global temperatures are linked to decreasing species body sizes across diverse taxa.
• Temperature-size relationships are well-studied in ectotherms, often attributed to developmental plasticity.
• In endotherms, warming-driven size changes are typically explained by natural selection, with less focus on plasticity.

Purpose of the Study:

• To review evidence for developmental plasticity in temperature-size relationships in birds.
• To explore insulin-like growth factors as a potential mechanism for plastic responses to temperature in endotherms.
• To assess the role of developmental plasticity in climate change-driven size reductions in birds.

Main Methods:

• Literature review of studies on temperature effects on bird body size.
• Analysis of existing data linking developmental temperature and body size in avian species.
• Identification of potential molecular mechanisms, such as insulin-like growth factors, mediating plasticity.

Main Results:

• Evidence supports a role for developmental plasticity in temperature-size relationships in birds.
• Warmer developmental temperatures are frequently associated with reduced adult body size in birds, mirroring ectotherm responses.
• Insulin-like growth factors are proposed as a plausible mechanistic link for these plastic responses.

Conclusions:

• Developmental plasticity may be a significant, underappreciated factor in warming-driven size reductions in endotherms like birds.
• Understanding plasticity's role is crucial for predicting biodiversity responses to climate change.
• Plasticity and natural selection impose different constraints, highlighting the need to differentiate their roles in evolutionary adaptation.