Phenotypic lags influence rapid evolution throughout a drought cycle.

Area of Science:

• Evolutionary biology
• Climate change science
• Plant ecology

Background:

• Increasing climate anomalies exert strong selection pressures, potentially driving rapid evolution.
• Interannual climate variability can complicate or counteract selection, impacting evolutionary trajectories.
• The influence of past climatic conditions on contemporary evolution is often overlooked.

Purpose of the Study:

• To investigate how climatic differences over a 7-year period, including a severe drought, influence rapid evolution in Mimulus cardinalis.
• To assess the association between plant trait values and various climate metrics across different time scales (collection year, prior years, cumulative).

Main Methods:

• Studied 12 populations of Mimulus cardinalis under controlled wet and dry greenhouse conditions.
• Measured specific leaf area and date of flowering as key plant traits.
• Analyzed trait associations with climate metrics from the collection year, 1-2 years prior, and cumulative across years.

Main Results:

• Anomalies in mean annual precipitation were the strongest predictor of trait differences over the study period.
• Climate conditions from 1-2 years prior to collection were often related to trait values in a direction opposite to the collection-year climate.
• Demonstrated that past climatic conditions can have a significant, sometimes opposing, effect on contemporary trait evolution.

Conclusions:

• Mean annual precipitation anomalies are key drivers of rapid evolution in Mimulus cardinalis.
• Interannual climate variability, including past conditions, plays a complex role in shaping evolutionary responses to climate change.
• Understanding these complex climatic impacts is crucial for predicting evolutionary responses to ongoing climate change.