Charles Darwin observed a unique beak size and shape in the finch population of each of the Galapagos Islands that he visited. 4
drawings of finch beaks. From left to right the beaks decrease in size. Which is the most likely cause of the observed variation? differences in the climate among the islands competition among individuals for available food sources competition among individuals for desirable mates differences in egg size among the populations
Natural selection would probably favor different varieties in the different islands. In other words, beaks changed as the birds developed different tastes for fruits, seeds, or insects picked from the ground or cacti (due to lack of food resources). Long, pointed beaks made some of them more fit for picking seeds out of cactus fruits.
