The researches working at the National Evolutionary Synthesis Center conducted a study where they reviewed the national selections of hundreds of species of birds, lizards, snakes, insects and plants. They found that the larger body size and earlier seasonal timing including breeding, blooming or hatching have a larger effect in their survival.
However, the puzzling part is that why the concept of “bigger is better” is so common in evolution study. The authors studied “Goldilocks” model known as stabilizing selection, where they argued the idea of having rare cases of being intermediate size that survive and reproduce better. For example, human birth weight: newborns of intermediate size are more likely to survive than newborns that are extremely large or small, but it is rare case. The reasons for why it’s so puzzling concept is because most creatures are well adapted to the environment in which they live.
The authors presented three possible explanations for this puzzling concept. One possibility is that evolving to be bigger and faster comes at cost meaning there can be a trade off between their survivals and reproducing. Another possibility is that the environments changes from seasons to seasons, in which the trait that has greater advantage changes over time such as in Darwin’s finches’ example, where large-beaked and small-beaked birds were favored due to availability of seeds. The third possibility is that natural selection drives one trait in one direction. For example, it can be advantage for flying insects to evolve larger wings and smaller bodies for more efficient flight; however, insects with larger wings having larger bodies cannot evolve.
From these explanations, the authors concluded that the third explanation limits the evolution of body size. However, the traits related to timing and/or body shape does not correlate with the idea of “Goldilocks” model.
Posted by Arpita Patel