Behavioral thermoregulation of flowers via petal movement

Widely documented in animals, behavioral thermoregulation mitigates negative impacts of climate change. Plants experience especially strong thermal variability but evidence for plant behavioral thermoregulation is limited. Along a montane elevation gradient, Argentina anserina flowers warm more in alpine populations than at lower elevation. We linked floral temperature with phenotypes to identify warming mechanisms, and documented petal movement and pollinator visitation using time-lapse cameras. High elevation flowers were more cupped, focused light deeper within flowers, and were more responsive to air temperature than low; cupping when cold and flattening when warm. At high elevation, a 20º increase in petal angle resulted in a 0.46ºC increase in warming. Warming increased pollinator visitation, especially under cooler high elevation temperatures. A plasticity study revealed constitutive elevational differences in petal cupping and stronger temperature-induced floral plasticity in high elevation populations. Thus, plant populations have evolved different behavioral responses to temperature driving differences in thermoregulatory capacity.

Methods
Data were collected in natural populations on floral phenotypes, floral and environmental temperature, petal movement and pollinator visitation and temperature. Temperature data was collected using thermocouple probes. Petal movement and pollinator data was collected using time-lapse cameras.

Data on floral phenotypes were also collected on greenhouse propogated plants in growth chambers.