Galapagos finch: the origin of species. Causes of differences in the structure of the beak

Due to the fact that the Galapagos Islands have never been part of the mainland and originated from the bowels of the earth, their flora and fauna are unique. Most of the representatives are endemic and do not occur anywhere else on Earth. These include different types of Galapagos finches. They were first described by Charles Darwin, who discovered their significance in the theory of evolution.

Origin of the species

Some scientists consider the endemic group of small birds to be a family of oatmeal, others to the family of tamarids. The second name - the Darwinian - they got thanks to their discoverer. A young and ambitious scientist was struck by the nature of the islands. He suggested that absolutely all finches in the Galapagos Islands have one common ancestor, who came here more than 2 million years ago from the nearest mainland, that is, most likely from South America.

All birds are small in size, the average body length is 10-20 cm. The main difference that prompted Charles Darwin to the idea of speciation is the shape and size of the feathered beak. They vary greatly, and this allows each species to occupy its own separate ecological niche. In addition, there are differences in the color of plumage (black and brown predominant) and vocalization. Observing the birds, the scientist suggested that initially only one species of finches came to the island. It was he who gradually settled on the islands of the archipelago, adapting to various conditions of habitat. However, not all the Galapagos finches were ready to live in harsh conditions. Beaks - that's what became the main criterion of natural selection. In the struggle for survival, the advantage was in those species from which they suited for local food. Some individuals received a variety of seeds, others - insects. As a result, the original (ancestral) species split into several others, each of which specializes in a specific food base.

As a result of his research and discoveries, a small Galapagos finch entered the world history of biology, and mysterious and distant islands became an open-air laboratory, which is ideal for observing the results of evolutionary processes.

Modern look

Inspired by Charles Darwin to create the theory of the evolution of the finch actively helped modern science in its confirmation. At least, this is said about by a scientist from the University of Princeton Peter Grant and his colleagues.

By their studies, they confirm that the cause of the appearance of different types of Galapagos finches lies in the fodder base and the struggle for it between different populations. In their work they say that in a fairly short time with one of the species of birds, such changes occurred. The size of the beak reel has changed as a result of the fact that the island arrived competitors, and food was limited. This took 22 years, which for evolutionary processes is almost equivalent to instants. In the finches, the beak diminished in size, and they were able to escape competition by switching to other food.

The results of more than 33 years of work were published in the journal Science. They confirm the important role of competition in the process of formation of new species.

A large number of finches breed on the islands, and all of them are endemic, but most often there are three main species from the group of earthen ones. Let us dwell on them in more detail.

Large cactus finch

A small songbird (photo above) lives on the four islands of the archipelago and, as it is easy to guess from the name, her life is closely related to cacti. This Galapagos finch uses them not only as a shelter, but also as food (flowers and fruits). The beak is elongated, strong, and is best suited for the production of insects and seeds. Color black, with gray spots in females.

Medium Earthen Finch

This is one of the types of singing finches discovered by Charles Darwin in the Galapagos Islands. The structure of the beak is strong, powerful, adapted for snapping seeds of small sizes. The basis of the diet is also composed of insects (in particular, it collects parasites from the skin of the horse and in the turtles), as well as berries. According to recent studies, this species can serve as a worthy example of early sympatric speciation. There are two populations (morphs), which slightly differ in the structure of the beak. However, this led to a difference in singing. As a result, the individuals of both populations inhabit one territory, but interbreed mainly only within the morphs.

Sharp earthen finch

The amazing Galapagos finch is known primarily for one of the subspecies - septentrionalis. His diet consists mainly of the blood of other animals that live on the island, in particular gannets. Sharp and thin beak, they literally pinch the skin until it begins to bleed. In this unusual way, they compensate for the body's need for fluids, whose reserves on the islands are extremely small. Presumably, this behavior has developed as a result of feeding by parasites, which the birds hatch from other animals.

In the species, sexual dimorphism is observed : males are predominantly of black plumage, and females are gray with brown spots.

Wood finches

The genus consists of six species, all of them endemic and live only in the Galapagos Islands. The fauna and flora of this place are extremely vulnerable and easily destroyed when they interfere. Developed separately from the whole world, the islands need protection and protection. In particular, mangrove wood fin is currently under threat of extinction. Small gray birds with olive breast live only on one island - Isabela, the population of about 140 individuals.

Interest is how this Galapagos finch feeds. He prefers large larvae of insects, it is sometimes difficult to get them from under the bark of a tree, so he uses a special tool (sticks, twigs, grass), which deftly digs inside. Similarly comes another bird from this genus - the woodpecker woodpecker (pictured), who prefers to use including cactus spines.