Spatial scale and temporal component of selection in side-blotched lizards

Area of Science:

• Evolutionary biology
• Ecology
• Population genetics

Background:

• Spatial variation in selection is crucial for population divergence and maintaining genetic diversity.
• Direct measurement of fine-scale spatial selection is challenging.
• Long-term ecological data are essential for understanding selection dynamics.

Purpose of the Study:

• To analyze spatial and temporal variation in selective regimes on egg size in the side-blotched lizard (Uta stansburiana).
• To investigate the joint effects of spatially and temporally variable selection on egg mass.
• To assess the correlation between local and global selection gradients and the degree of spatial synchronization in selection.

Main Methods:

• Analysis of long-term population data of the side-blotched lizard (Uta stansburiana).
• Calculation of local selection gradients at the neighborhood level and global selection gradients at the metapopulation level.
• Assessment of spatial synchronization of local selection gradients for different clutch timings.

Main Results:

• Juvenile survival rates exhibited significant spatial and temporal variation, interacting at the local neighborhood level.
• Spatially and temporally variable selection acted on egg mass, potentially maintaining high additive genetic variance.
• Local selection gradients correlated with global gradients, but substantial local variance suggests global analysis may miss fine-scale selection.
• Selection synchrony was higher for later-clutch hatchlings, attributed to density- and frequency-dependent selection.

Conclusions:

• Fine-scale spatial variation in selection is a significant factor in evolutionary processes.
• Understanding local selection regimes is critical, as they can differ substantially from metapopulation-level trends.
• Density- and frequency-dependent selection likely play a role in synchronizing selection later in the breeding season.