Microscale trait-environment associations in two closely-related South African shrubs

Area of Science:

• Ecology
• Plant Science
• Evolutionary Biology

Background:

• Plant traits often correlate with environmental conditions.
• These trait-environment associations can vary significantly across different spatial and phylogenetic scales.
• Understanding trait variation within populations requires examining microenvironmental influences.

Purpose of the Study:

• To investigate the relationships between microenvironment, microgeographical location, and functional traits within populations of two closely related Protea species.
• To determine if observed trait-environment associations in the field are genetically determined or environmentally induced.

Main Methods:

• Measured functional traits on 147 Protea plants across an elevational gradient on a mountainside.
• Characterized microenvironments using data-loggers and soil analyses at 10 microsites.
• Employed Bayesian path analyses to assess trait-environment relationships and conducted greenhouse experiments with seedlings to test for genetic differentiation.

Main Results:

• Significant differences in microenvironmental variables were observed across the study site.
• Six trait-environment associations were identified, with distinct patterns between the two Protea species.
• No similar trait-environment associations were detected in greenhouse-grown seedlings, suggesting a lack of genetic basis for field observations.

Conclusions:

• Several leaf traits showed associations with temperature and soil conditions in the field.
• The absence of these associations in controlled greenhouse conditions indicates that the observed field patterns are likely due to phenotypic plasticity rather than genetic differentiation.
• This suggests that Protea populations can adjust their traits in response to local microenvironmental variations without underlying genetic changes.