Merzlyak et al. (2008) discusses a number of functions proposed for anthocyanins. Why would the authors expect higher concentrations of anthocyanins in autumnal leaves than spring leaves?
a. Anthocyanins act as toxins to leaf predators. Spring leaves experience lower rates of herbivory than autumnal leaves.
b. Anthocyanins are complex molecules requiring high energy output by plants. Autumnal leaves show higher concentrations of anthocyanins because plants have more available energy at the end of the growing season.
c. Anthocyanins mitigate the effects of UV exposure. Anthocyanins build up throughout the growing season leading to higher concentrations in autumnal leaves.
d. Anthocyanins are used to attract pollinators. Autumnal leaves have higher production of anthocyanins to attract pollinators when flowers are present on the plants.
