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

2024 Author: Henry Conors | [email protected]. Last modified: 2024-02-12 02:55

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 are not found 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

An endemic group of small birds, some scientists refer to the bunting family, others to the tanager. The second name - Darwin - they received thanks to their discoverer. The young and ambitious scientist was amazed by the nature of the islands. He suggested that absolutely all finches on the Galapagos Islands have one common ancestor that 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 body length is on average 10-20 cm. The main difference thatprompted C. Darwin to think about speciation - the shape and size of the beak of birds. They vary greatly, and this allows each species to occupy its own separate ecological niche. In addition, there are differences in plumage color (black and brown are predominant) and vocalization. Watching 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 environmental conditions. However, not all Galapagos finches were ready for life in harsh conditions. Beaks - that's what has become the main criterion of natural selection. In the struggle for survival, those species in which they were suitable for local food had an advantage. 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, the small Galapagos finches entered the world history of biology, and the mysterious and distant islands became an open-air laboratory, which is ideal for observing the results of evolutionary processes.

Modern look

The finches that inspired Charles Darwin to create the theory of evolution have actively helped modern science to confirm it. At least that's what Princeton University scientist Peter Grant and his colleagues say.

By their research, they confirm that the reason for the appearance of different speciesGalapagos finches lies in the food base and the struggle for it between different populations. In their work, they say that in a fairly short period of time such changes have occurred with one of the varieties of birds. The size of the finch's beak has changed as a result of the fact that competitors arrived on the island, and there was a limited amount of food. It took 22 years, which for evolutionary processes is almost equivalent to moments. The finches' beaks have been reduced in size, and they have been able to escape competition by switching to other food.

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

A large number of finches nest on the islands, and they are all endemic, but the three main species from the group of ground finches are most often found. Let's dwell on them in more detail.

Large cactus finch

A small songbird (photo above) lives on four islands of the archipelago and, as you might guess from the name, its life is closely connected with cacti. This Galapagos finch uses them not only as shelter, but also for food (flowers and fruits). The beak is oblong, strong, it is best suited for obtaining insects and seeds. The color is black, with gray spots in females.

Medium Ground Finch

This is one of the species of song finches discovered by C. Darwin in the Galapagos Islands. The structure of the beak is strong, powerful, adapted for clicking seeds of small sizes. basisthe diet also consists of insects (in particular, it collects parasites from the skin of conolophos and in turtles), as well as berries. According to recent studies, it is this species that can serve as a worthy example of early sympatric speciation. There are two populations (morphs) that differ slightly in the structure of the beak. However, this resulted in a difference in singing. As a result, individuals of both populations live in the same territory, but interbreed mainly only within the morph.

Sharp-billed Groundfinch

The amazing Galápagos finch is best known for one of its subspecies, septentrionalis. Its diet consists mainly of the blood of other animals living on the island, in particular gannets. With a sharp and thin beak, they literally pinch off the skin until it starts to bleed. In such an unusual way, they compensate for the body's need for fluid, the reserves of which on the islands are extremely small. Presumably, this behavior developed as a result of feeding on parasites that birds pecked out from other animals.

The species has sexual dimorphism: males are predominantly black plumage, and females are gray with brown spots.

Tree finches

The genus consists of six species, all of them are endemic and live only on the Galapagos Islands. The fauna and flora of this place are extremely vulnerable and easily destroyed when tampered with. Developing in isolation from the whole world, the islands need protection and protection. In particular, the mangrove tree finch inis currently in danger of extinction. Small gray birds with an olive breast live on only one island - Isabela, the population is about 140 individuals.

Interesting is how this Galapagos finch eats. He prefers large insect larvae, which are sometimes difficult to get out from under the bark of a tree, so he uses a special tool (sticks, twigs, blades of grass) with which he deftly digs inside. Another bird from this genus acts similarly - woodpecker tree finch (pictured), preferring to use cactus thorns as well.