A Fascinating Evolution

By Emily Arendsen

I have had a growing fascination for plants that has been the focus of my studies for the past two years. I find their diversity astounding because they have all developed strategies to overcome different obstacles. Some plants adapted to handle high light environments with little water, others adapted to be able to survive flooding events in salt water. Every day, I find something astounding that a plant has done in order to survive in a highly competitive forest and that fuels my fascination.

            One challenge that all plants face is pollination, which has been one of the themes of this week in Monteverde. The best option for plants is sexual reproduction in which the pollen from one plant reaches the stigma of a flower from a different plant. Plants are sessile so they need to get somebody else to do the work for them. The answer is pollinators and crafty evolution. Pollinators can be bats, bees, beetles, birds, butterflies, moths, or even flies. Pollinators move the pollen from one plant to another, but that doesn’t help the plants if the pollen lands on the stigma of a different species because they will not be compatible. In order to reduce pollen waste and to increase the chances of the pollen reaching the receptive stigma of its own species, plants have had to diversify their flower anatomy to exclude certain pollinators based on the anatomy and preferences of the pollinator. Bird-pollinated flowers typically have reddish colors and long, tubular, odorless flowers because birds respond to red and hummingbirds have elongated beaks that can reach into the flowers for nectar. Bat-pollinated flowers do not invest in color and open during the night because bats come around at night, however they do have a strong, musky odor. The petals are often strong to keep the flower intact while its large pollinator visits. Bee-pollinated flowers are usually light colors like white, yellow and green and have spots or lines that lead from the end of the petal to the inside of the flower to guide the bees to the nectar. Butterfly-pollinated flowers are brightly colored and have a landing platform for the butterflies to land on. These characteristics are collectively called pollinator syndromes.

                  One of our class periods was spent collecting flowers and using their characters to determine which pollinator syndrome they have. We collected flowers from different trails in the Children’s Eternal Rainforest and brought them back to the station to sort them into piles of their likely pollinators. The most abundant pollinator syndrome of the flowers we collected was bee-pollinated and one of the least common was butterfly-pollinated. We then had my favorite writing exercise thus far in which we had to choose a pollinator and explain how we would go about restoring their populations if we were the land manager of a large nature reserve that was experiencing a decline in pollinators. This was an interesting exercise because we were able to apply prior knowledge with the information we had just worked with to think about an important ecological problem.