Don’t forget about plant sex: climate change can affect sex ratios in plants

Most climate change studies on plants are focused on how the growth or range of a plant species will response to a changing climate. The sex of the plant is usually ignored, and in some cases this is okay since some plants have both male and female structures on an individual. However, dioecious plants have a particular sex for an individual, much like dogs and cats. Males and females of dioecious plant species can have different physiology, and this may affect male/female responses to climate change in these species.

Petry et al. (2016, Science, 353:69-71) sought to determine whether males and females of a dioecious plant would respond differently to climate change. They looked at how the sex ratio changed across the entire range of the herb, Valeriana edulis, over the past 33 years. They found the proportion of males in the population decrease with elevation, but the proportion of males overall has increased by ~6% over the past 33 years. They attribute these results to differences in water use efficiency (the ability of a plant to conserve water while maintaining growth). The sex with the greater proportion in a population had higher water use efficiency than the other sex. However the reason for these differences is unclear.

The results of Petry et al. have significant implications for modelling. If we assume that both sexes of a dioecious plant species are the same, our models of plant migration or populations could be wrong. Modellers will have to take this into account when trying to predict migration patterns of plants, and potentially even carbon uptake. It boils down to one thing: sex does matter, and it can no longer be ignored in plant modelling efforts.

Stay safe and stay informed,