Environmental and Biogeographic Drivers behind Alpine Plant Thermal Tolerance and Genetic Variation.

Area of Science:

• Ecology
• Evolutionary Biology
• Plant Physiology

Background:

• Alpine ecosystems present steep thermal gradients, influencing plant community composition and potentially driving thermal tolerance and genetic divergence.
• Limited research exists on the range of alpine plant thermal tolerances and their genetic underpinnings across environmental gradients.

Purpose of the Study:

• To investigate thermal tolerance thresholds (photosystem heat and cold) in ten Australian alpine species along elevation gradients.
• To characterize neutral genetic variation within these species.
• To reconstruct historical habitat suitability to understand biogeographical influences on genetic patterns.

Main Methods:

• Measurement of photosystem critical heat (T_crit-hot) and cold (T_crit-cold) thresholds for ten alpine species.
• Analysis of neutral genetic variation across populations.
• Habitat suitability modeling to reconstruct past and predict future distributions.

Main Results:

• Intraspecific variation in thermal thresholds was observed but not correlated with elevation or local genetic differentiation.
• Regional population differentiation and high homozygosity were linked to historical contractions, persistence, and migrations driven by habitat suitability changes.
• Habitat suitability models indicate a threat to cool-climate-adapted alpine plants from climate warming.

Conclusions:

• Observed wide thermal tolerances in alpine plants do not fully reflect their vulnerability to climate change.
• Conservation strategies must consider species-specific thermal tolerance variations across diverse alpine microclimates.
• Understanding historical biogeography is crucial for predicting alpine plant responses to future climate scenarios.