Adaptive Radiation And Species Diversification

According to Darwin and his theory on evolution, organisms are presented with nature’s challenge of environmental change. Those that possess the characteristics of adapting to such challenges are successful in leaving their genes behind and ensuring that their lineage will continue. It is natural selection, where nature can perform tiny to mass sporadic experiments on its organisms, and the results can be interesting from extinction to significant changes within a species.

When a species gives rise to a new species the small group breaks away and becomes geographically/reproductively isolated from its ancestral group. As long as it remains small and detached, the founder group can experience fairly rapid genetic changes.

Gene flow: genetic additions and/or subtractions from a population resulting from the movement of gametes

Assignments 1: I developed a hypothesis to predict that the island with the finches with the larger beak will be able to adapt more rapidly to their surrounding and handle the hard seeds of their island verses the island with the finches with the smaller beaks. I left the primary beak size on Darwin

This occurs when a species is separated and mate with a different species, changing their genetic composition, if then the two species were to be brought back together and mate again, it would cause what is called ‘gene migration’. This process gives so many different variations among the species, which allows more and more variation and population. This process also explains endangered species and extinction.

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,

Natural sources of variation include: mutations, gene flow, and genetic shuffling. Mutations are random changes in DNA that result in beneficial, harmful, or no changes in an organism. Gene flow can also be referred to as migration. It is the exchange of genes of individuals from one population to another. Genetic shuffling occurs in meiosis when alleles switch to create new combinations of genes. The steps of natural selection are overproduction, variation, competition, and selection. Overproduction is important because it keeps the species from becoming extinct and allows for more variation in offspring. Variation is what can either help the organism have a higher chance of surviving or could lower the chance of surviving.

This lab is designed to help understand how precipitation, variance, and area have a role in the evolution of a species, in this case, Finches. It also explains the different types of selection.

On the Galápagos Islands off the coast near Ecuador we studied the behaviors of the animals, plants and environment on Daphne Major we found that the lack of rainfall during the wet season of 1977 caused most of the plants to produce less seeds and thus most of the medium ground finches died of starvation as their main food source had become scarce. Although the lack of seeds some finches were able to survive with their longer and bigger beaks. They were able to survive because their beaks were able to break open the harder and more plentiful Tribulus seeds that survived the dry season of 1977.

2. Allopatric speciation occurs due to a geographic isolation process such as when a pond might dry up and create two ponds, a flood, a river is re-routed, or a bird carries seeds in its feathers and drops the seeds in new location during the birds migration. The species of the previous geographic location also become reproductively isolated. The population then becomes two separate populations and begins to change over time due to changes in the gene pool, environments, natural selection and mutations. With this understanding it is possible to see that plate tectonics theory and continental drift theory possibly resulted in allopatric speciation.

In the Galapagos Islands there is an island named, Daphne Major, this island plays as the host of the Galapagos finches. In 1976 - 1977 there was an absolute near extinction of these finches. This is because of the drought of 1976 and 1977 (see figure 1). While the drought made the Finch population dwindle there was a hidden trait that was helping some survive, and that is beak size. Why did the larger beaks help those fortunate Finches survive? Because the only plants that survived where plants like the Tribulus, which produces hard shelled seeds. While there was an abundance of hard shelled seeds there was a shortage of soft shelled seeds. The finches that had the larger beaks weighed more, for example, survivors weighed approx. 12.5g to 17.5g with beak sizes going from 10.5 to 13.6(for evidence see figure 2. This reduced the population because the Finch’s with the smaller beaks couldn't open the harder seeds and had to scavenge for soft seeds which were very rare. The finches with small beaks, then died from starvation

A. Gene flow is the movement of genes is a population, causing a change is the most common characteristics. Genetic drift is very similar, it describes the evolution of a population to favor advantagous phenotypes. Natural selection is the survival of the fittest, that those best equipped to survive will reproduce and pass on their genes. Mutation is the random change of genetic material in an organisms DNA.

“If no such variations exist, the population rapidly goes extinct because it cannot adapt to a changing environment” (O’Neil, 1998-2013). Scientists call this reproductive success. “Within a specific environment context, one genotype will be better than another genotype in survival or reproduction for certain reasons having to do with the way its particular features relate to the environment or relate to other organisms within the population” (Futuyma, 2000-2014). The theory of evolution is explicable through various kinds of scientific research.

Overtime, a population may grow, develop and interact with its environment. During that interaction, different mechanism such as evolution may occur. Evolution which is the change in allele within

Evolution refers to change over time as species modifies and separate to produce several offspring species.