Geospiza Filiginosa Hypothesis

Charles Darwin, a naturalist born in 1809 England, traveled around the world on the HMS Beagle from 1831-1836 (Desmond). He made observations on land for three out of the five years he traveled around the world; his most significant findings were recorded on the Galápagos Islands. The most crucial evidence of evolution, a theory that Darwin is known for, consist of the different species of Galapagos tortoises and finches that Darwin observed. He noticed that depending on the different islands similar finches had different variations of beak size and shape. To add, he observed that the tortoise's shell shape and neck length varied based on which island they resided on. Darwin made the observation that depending on each island, which had different

One of its most important characteristics is its beak. The finch adapted to have a thin, long beak to probe through moss, bark and leaves in search of food (Wildscreen Arkive, N.D.). These finches have the thinnest beak out of the 13 finches; which aids them to find small insects. The Green Warbler finch are mostly found in humid highland forest where their primary food source is found. These adaptations made them more fit to survive on available food. Over the years the finch’s beak has evolved as the bird developed different taste for insects. Another famous adaptation is how they camouflage in their environment. The Green Warbler is restricted to the forest and is greener in body colouration, while the Gray Warbler is found in shrubby, dry thickets and is greyer and duller looking (Certhidea olivacea, 2010). Their coloration helps them camouflage in their own environments, and to hide from predators. Recent studies have found that there are in fact two separate species of the Warbler Finch, the Green Warbler Finch and the Grey Warbler Finch, but are considered as a single species (Wildscreen Arkive, N.D.). The Green Warbler finch mainly occupies larger, inner islands, while the Grey Warbler finch inhabits the smaller, outer islands (Green Warbler Finch,

Charles Darwin began his scientific breakthroughs and upcoming theories when he began an expedition trip to the Galapagos Islands of South America. While studying there, he discovered that each island had its own type of plant and animal species. Although these plants and animals were similar in appearance, they had other characteristics that made them differ from one another and seem to not appear as similar. Darwin questioned why these plants and animals were on these islands and why they are different in ways.

When Darwin traveled over to the Galapagos island he traveled on a ship called the HMS Beagle. Darwin traveled to the Galapagos island to get information about evolution with the animals there. When he was there he observed tortoises, when he observed these animals he got a understanding of evolution over time. He saw that the tortoises in the area with food low to the floor had a flatter shell and a short neck, but when he observed tortoises with food high up he saw that the tortoises had a long neck and raised shell. Over time the tortoises evolved she they can survive in their environments. When he was their he wrote a book called the Darwins book on the origin of species. The information that he wrote about was information about species that were not fixed but could change over time by natural causes.

Evolution and natural selection drive biodiversity by introducing selection pressures to individuals and populations forcing organisms to adapt to survive. Individuals that possess a certain trait that allow them to survive and reproduce, create offspring that also possess the advantageous trait. The population begins to change as more and more individuals now have the adaptation. Those that do not may begin to disappear or may begin to change their habits. Our text uses the example of Hawaii's many varieties of honey creepers. Each adapted differently to the conditions in which they lived. More specifically, their bill sizes and shapes varied depending on the types of food they preferred Withgott & Brennan, 2011). As a result, many of the plants on the Hawaiian Islands adapted their flowers in order to take advantage of the help these birds gave to each plant species fertilization methods (Withgott & Brennan, 2011).

Genetic drift is often found in populations living on the islands because of the habitat isolation, the process of natural selection, interspecific and intraspecific competitions. Therefore, the species on the island always face the the limitation of food source, living space and predation issues, that’s why their population size is forced to decrease and sometimes extinct.

Similar to the Galapagos finches, Anolis lizards of the Caribbean islands have evolved into an extremely diverse species, and it can be assumed that these series of species all diverged from a common ancestor many years ago. Therefore, biologists have developed two contrasting theories to explain the evolutionary relationships between the types of Caribbean Anolis lizards. Either the ecomorphs all evolved on one, large island and then split onto different islands, or the ecomorphs evolved repeatedly and independently from each other on separate islands. Based on the data, the latter is most heavily supported - that speciation of the Anolis lizards occurred on different islands and from common ancestors independent from each other.

Evolution is often thought to only take place over the course of millions of years. Because of this, it is commonly believed that it is impossible to observe evolution within a human lifetime. However, two scientists were able to observe evolution taking place over the course of only a few years. Peter and Rosemary Grant studied the birds named after Charles Darwin that live on the Galapagos Islands. Darwin was able to study these finches and develop his theory of natural selection from his observations.

The box plot depicts the beak depth of finches in the Galapagos islands. 267 samples were collected in the year 1976, to the left, and 33 samples were collected in 1976, to the right. The plot to the left shows multiple outliers, which makes it inappropriate to assume normality; however, since the sample size is large normality can be assumed. The plot to the right has one outlier, which makes it appropriate to assume normality. Overall, we can also observe that the mean beak depth increased by a few millimeters in 1978. Further test we reveal if this difference has significance.

Another example of speciation is the North American butterfly, David Wright making a discovery in 2002 that a new species of butterfly in which was large and colourful knowsn as Papilio. From further research Davis soon discovered the apparent mixture in this species of two closely related species. These being the Canadian tiger swallowtail and the eastern tiger swallowtail. These two formed the new butterfly in which occurs in cooler thermal habitat at mid-to high elevations getting this from the Canadian tiger

Beak adaptations help to provide evidence for evolutionary theory, which was explained well in the background of our lab manual for this lab. More specifically where both artificial and natural selection were discussed and highlighted as evidence of evolution itself (Hands-On, n.d.). Within our manual, it gives great examples of how Darwin noticed birds like the cactus finches who had beaks that were pointed more and longer than that of their relatives that dwelled on the ground (Hands-On, n.d.). In addition to this, Darwin also saw that finches known as warblers had beaks that were both pointed and thinner more than that of ground and cactus finches (Hands-On, n.d.). These types of adaptations, or even the different shape and size of beaks

Prior to Spanish discovery of the islands in 1535, there is little evidence to support any permanent settlement. Spaniard Fray Tomas de Berlanga’s vessel drifted off course on a trip to Peru and reached the islands. The English followed in 1593, and Irish sailor Patrick Watkins is believed to be the first to establish a permanent settlement on Floreana, when he was stranded between 1807 and 1809. In 1959, the Galapagos was designated a national park, and in the

The birds on island one and two, have similar beaks as the mainland birds. The beak starts to bend more which allows the birds to hunt insects and cactus flowers. Island 3 has a slightly smaller beak then the mainland and would be used to hunt insects and island four has a smaller but stronger beak which means the island would have many nuts and hard shells that the bird could open with its beak.

Darwin’s theory of evolution is the most commonly accepted theory because of the strong evidence that the theory is built on. One of the most famous examples of Darwin’s theory is the Galapagos finches. Darwin observed different finches from different islands of the Galapagos. He found that the finches from all the different islands had differently evolved beaks. Darwin

While on the Galápagos Islands, Darwin kept notebooks about all the species there, and he noticed the variety of tortoises on the island who were essential in explaining his theory of evolution. There are several species of tortoise present on the Galápagos Islands that are all very closely related, but slightly different. There are eleven presently surviving subspecies of Galápagos tortoises; furthermore, six of the eleven are found on different islands in the archipelago, and the other five are all found on a single island on five separate volcanoes with their own mini-ecosystems (PNAS). Although all of the species of Galápagos tortoise is different, they each have small differences that can include maximum adult size, shell shape, and the length of the neck and limbs. The tortoises of the islands are most closely related to the Chaco tortoises along the western coast of South America, and they most likely came to the Galápagos by “rafting” across the water (PNAS). Similar to the tortoises, Darwin observed that the Finches on the islands also had changed to match the environment. Spread among the islands were fourteen subspecies of finch whose