Partitioning within-species variance in behaviour to within- and between-population components for understanding...

Area of Science:

• Evolutionary biology
• Behavioral ecology
• Quantitative genetics

Background:

• Phylogenetic comparative studies primarily focus on interspecific trait variation, neglecting the evolutionary significance of within-species variance components.
• Within-species variance, including between-population and between- or within-individual variances, plays a crucial but understudied role in shaping evolutionary trajectories.

Purpose of the Study:

• To partition the variance in flight initiation distance (FID), an anti-predator behavior.
• To investigate the relationship between within- and between-population variance in FID and various ecological and life-history traits.
• To highlight the importance of considering trait variance in evolutionary ecology.

Main Methods:

• Partitioning of variance in flight initiation distance (FID) into within- and between-population components.
• Phylogenetic comparative analyses incorporating corrections for allometry, density-dependence, phylogenetic uncertainty, and data quality.
• Statistical modeling to assess the association of variance components with ecological and life-history variables.

Main Results:

• The majority of FID variance was found within populations, though its composition was influenced by phylogeny.
• Within-population variance in FID was significantly associated with habitat diversity and population size after accounting for confounding factors.
• Between-population variance in FID significantly predicted natal dispersal, senescence, and habitat diversity.

Conclusions:

• Both the mean and the variance of behavioral traits within and among populations are critical for understanding species' evolutionary ecology.
• Within-species variation in traits like FID provides valuable insights into adaptation, dispersal, and life-history evolution.
• Future evolutionary studies should explicitly incorporate the hierarchical components of trait variance.