Group items tagged

In their study of the medium ground finches, evolutionary biologists Peter and Rosemary Grant were able to track the evolution of beak size twice in an amazingly short period of time due to two major droughts that occurred in the 1970s and 1980s. This activity simulates the food availability during these droughts and demonstrates how rapidly natural selection can act when the environment changes. Students use two different types of tools to represent different beak types to see which is best adapted to collect and "eat" seeds of different sizes. Students collect and analyze data and draw conclusions about traits that offer a selective advantage under different environmental conditions. They have the option of using an Excel spreadsheet to calculate different descriptive statistics and interpret graphs.

In a study published Thursday in the journal Science, they report that they've pinpointed the bit of finch DNA behind the swift transition: a gene called HMGA2. In finches, HMGA2 seems to be the primary factor in beak size - like a really good group project leader, it orchestrates the expression of a number of other genes, each of which tweaks the size of the bird's beak. The same gene also appears in dogs, horses, even humans, holding sway over body size and stature.