Temperature-dependent pollinator-mediated selection on floral thermoregulation

Area of Science:

• Ecology
• Evolutionary Biology
• Plant Science

Background:

• The thermal environment significantly influences plant survival and reproduction.
• Plants often cannot control their microclimate, making coping with temperature extremes crucial.
• Floral traits can modify the thermal microenvironment, potentially mitigating negative effects of temperature extremes on plant reproductive success and interactions with pollinators.

Purpose of the Study:

• To quantify selection on floral thermoregulation, defined as the deviation of floral temperature from ambient air temperature.
• To investigate pollinator-mediated and viability selection on floral thermoregulation in two populations of *Argentina anserina*.
• To determine how selection on floral temperature varies with geographic location and ambient temperature.

Main Methods:

• Quantified pollinator-mediated and viability selection on floral thermoregulation.
• Utilized three fitness components to assess selection.
• Compared selection patterns in alpine and lower elevation populations of *Argentina anserina* over two seasons.

Main Results:

• At high elevations, pollinators favored floral warming, evidenced by increased seed number and pollen export.
• At low elevations, selection favored floral cooling via pollen viability in one season.
• Across populations and years, selection favored floral warming under cooler conditions and cooling under warmer conditions, primarily driven by pollinator-mediated selection.

Conclusions:

• Provides the first direct evidence of temperature-dependent selection on floral temperature modulation.
• Geographic differences in selection patterns suggest local adaptation of plant thermoregulatory mechanisms.
• Floral temperature regulation is a key trait influenced by environmental temperature and pollinator preferences.