Changes in phenology mediate vertebrate population responses to temperature globally

Area of Science:

• Ecology
• Evolutionary Biology
• Climate Change Biology

Background:

• Phenotypic plasticity and evolutionary adaptation are key responses to climate change.
• Understanding how climate-driven phenotypic changes impact population dynamics is crucial for conservation.
• The relationship between climate, phenotype, and population size in wild vertebrates remains incompletely understood.

Purpose of the Study:

• To investigate the global impact of climate on vertebrate phenotypes and population dynamics.
• To determine if phenological shifts in response to climate positively influence population growth.
• To explore how latitude and other factors mediate the effects of climate on population dynamics.

Main Methods:

• Assembled 213 global time series of vertebrate phenotypes and population sizes.
• Matched phenotypic and population data with local climate data.
• Conducted a meta-analysis to assess climate sensitivity of morphological and phenological traits and their effects on population growth.

Main Results:

• Morphological traits showed limited sensitivity to climate variations.
• Earlier phenology in warmer years positively correlated with population growth in most species.
• Lower latitude populations experienced weaker phenological responses but stronger direct negative impacts from temperature, suggesting limited adaptive capacity.

Conclusions:

• Phenological shifts are a key mechanism linking climate warming to population dynamics in vertebrates.
• The direct negative effects of warming on population growth at lower latitudes underscore the complex and varied impacts of climate change.
• Predicting population responses to climate change requires considering local-scale factors and intra-specific variation beyond broad species characteristics.