MEASURING SELECTION AND CONSTRAINT IN THE EVOLUTION OF GROWTH

Area of Science:

• Quantitative genetics
• Evolutionary biology
• Developmental biology

Background:

• Understanding the evolution of growth trajectories is crucial for predicting population dynamics and adaptation.
• Previous models often assumed specific growth curve shapes, limiting their applicability.
• The interplay between genetic variation and selection shapes evolutionary trajectories.

Purpose of the Study:

• To develop a quantitative genetic model for growth trajectory evolution without assuming specific shapes.
• To identify the key genetic and selective factors governing the evolution of growth.
• To investigate potential constraints on evolutionary changes in growth patterns.

Main Methods:

• Developed a flexible quantitative genetic model for growth trajectory evolution.
• Defined the roles of the selection gradient and additive genetic covariance functions.
• Empirically estimated these functions using data from four vertebrate populations and mouse genetic data.
• Utilized computer simulations to explore evolutionary constraints.

Main Results:

• Population mean growth trajectory evolution is determined by selection gradients and additive genetic covariance.
• Selection gradients can be estimated from birth and death rates across ages.
• Additive genetic covariance functions were empirically estimated in four vertebrate populations.
• Computer simulations revealed that lack of genetic variation can constrain growth trajectory evolution.
• Analysis of covariance functions visualized these evolutionary constraints.
• Most evolutionary changes in growth trajectories showed limited or no available genetic variation across populations.

Conclusions:

• Quantitative genetic models can effectively describe growth trajectory evolution without shape assumptions.
• Selection gradients and additive genetic covariance are key determinants of evolutionary growth.
• Genetic variation significantly constrains the evolution of growth trajectories.
• Constraints imposed by limited genetic variation likely play a substantial role in the evolution of growth across diverse species.