During 1977 there was a drought on Daphne Major that resulted in a higher than normal mortality rate for the finches, so the Grants investigated finch characteristics that may have contributed to the survival of the remaining birds. Darwin's finches are well known for their remarkable diversity in beak form and function. On his visit to the Galapagos Islands, Charles Darwin discovered several species of finches that varied from island to island, which helped him to develop his theory of natural selection. Field studies have shown that beaks evolve by natural selection in response to variation in local ecological conditions. Medium Ground-Finch Geospiza fortis. It was part ground finch, part cactus finch, and quite large compared to the locals. Passeriforme Order – Thraupidae Family. The Grants discovered those with a higher beak size survived more from the drought, thus leading to a natural selection for slightly larger beak sizes in the population of medium ground finches. They are divided into 4 groups: Genus Geospiza: 1. Grant is a fellow of the Royal Society and was a Guggenheim Fellow in 1985- ... dent populations-the medium ground finch, Geospiza fortis, and the cactus finch, G. scandens-to a number that Large Cactus-finch. Darwin studied the geology of the region along … Learn vocabulary, terms, and more with flashcards, games, and other study tools. The Grants collected data on Medium Ground Finches, Geospiza fortis, on Daphne Major, one of the Galapagos Islands. The Grants found changes from one generation to the next in the beak shapes of the medium ground finches on the Galápagos island of Daphne Major. 3.4 Natural selection in Darwin's finches. Describe the beak sizes of the medium ground finch population (species #12 in the finch cards). Darwin called this mechanism of change natural selection. Start studying 7.11C identify some changes in genetic traits that have occurred over several generations through natural selection and selective breeding such as the Galapagos Medium Ground Finch (Geospiza fortis) or domestic animals.. 2. The Galapagos Islands are an archipelago of 13 major islands and more than a hundred smaller islands that straddle the equator off the Ecuadorian coast. INTRODUCTION: As another example of the Darwin’s theory of evolution, the Medium Ground-Finch exhibited decrease in bill size on Daphne Major Island, after El Niño event (1982-83) involving heavy rains and reduced crop of hard, large seeds usually eaten by this species. Darwin's finches, inhabiting the Galapagos archipelago and Cocos island, constitute an iconic model for studies of speciation and adaptive evolution. The medium ground finch (Geospiza fortis) is a species of bird in the family Thraupidae.It is endemic to the Galapagos Islands.Its natural habitats are subtropical or tropical dry forests and subtropical or tropical dry shrubland.One of Darwin's finches, the species was the first which scientists have observed evolving in real-time. Learn vocabulary, terms, and … generations through natural selection and selective breeding such as the Galapagos Medium Ground Finch (Geospiza fortis) or domestic animals. Natural Selection and Darwin's Finches The {inches of the Galapagos-the classic example of how ... Large Cactus Finch of the Galapagos. Medium Ground-Finch Geospiza fortis.