Warming at the population level: Effects on age structure, density, and generation cycles

Area of Science:

• Ecology and Evolutionary Biology
• Climate Change Biology
• Population Dynamics

Background:

• Climate change effects on age-structured ectotherm populations are understudied.
• Temperature significantly influences ectotherm developmental rates and population dynamics.
• Pyralid moth (Plodia interpunctella) populations exhibit generation cycles due to age-related competition.

Purpose of the Study:

• To investigate the impact of warming and resource availability on Plodia interpunctella population dynamics.
• To understand how climate change affects age structure and population density in ectotherms.

Main Methods:

• Experimental manipulation of temperature (ambient, +3°C, +6°C) and diet quality.
• Monitoring population density, age structure, and life cycle dynamics of Plodia interpunctella.
• Analysis of interactions between temperature and resource availability on population parameters.

Main Results:

• A 3°C warming increased adult population size by ~50% due to reduced larval competition.
• Warming disrupted typical generation cycles when combined with standard diet, but not with nutrient-poor diet.
• A 6°C warming resulted in rapid population extinction or persistence at very low densities.

Conclusions:

• Moderate warming significantly alters population structure and dynamics in age-structured ectotherms.
• Warming interacts with resource availability to modify population cycles and stability.
• Findings are relevant to economically important species with similar population cycling mechanisms.