March 6, 2014
Analysis of the Pollinator Shift Model
In the journal article, "Pollinator Shifts Drive Increasingly Long Nectar Spurs in Columbine Flowers" by Justin B. Whittall and Scott A. Hodges, the theories of Darwin's coevolution race model and the pollinator shift model are compared and contrasted. The article begins by dissecting the differences in each theory with the emphasis on the pollinator shift model. The coevolution theory suggests that both moth tongues and plant spurs developed simultaneously, while the pollinator shift model suggests that the pollinators' tongues developed first before the plant spurs caught up evolutionarily. One of Whittall's main explanations for why the pollinator shift likely occurred is because short tongued pollinators will not interbreed with the long to short spurred plants. The way Whittall came to this conclusion was through phylogenic analysis between the spur lengths of different plants throughout their evolutionary history. The process of analyzing phylogenics requires a super-computer to factor each variable resulting in the maximum parsimony. The results concluded that there were multiple shifts throughout the plant species under observation. Seven different independent shifts were recorded between unrelated pollinators with five of them belonging to the hawkmoth population. The results also depict the idea that the shift was beneficial for the plants because they did not reverse the outcome of the pollinator shifts. These pollinator shifts are described as coincidental, meaning that the pollinators’ tongues become longer and as a result, the plants became unable to attach their pollen to these pollinators decreasing the chances of reproductive success, so these plants needed to adapt to avoid an evolutionary dead end. Whittall claims that, "The only decrease in spur length occurred for the smallest pollination syndrome contrast. Furthermore, large pollination syndrome contrasts are correlated...