The finches on the Galapagos Islands are a good example of adaptation because they all trace their ancestry into a small group of finches that inhabited these islands, but diversified in accordance to the environment. On the Galapagos Islands, there are finches that have numerous types of different beak shapes and sizes, despite them all being derived from a single group of finches that had the same characteristics. The reason for this is that once they got to these islands, there were multiple niches int the food chain that were free for taking. Some finches started to feed on plants, some on seeds, some became insect-eaters etc. Every food type needs special adaptation so that the finches can eat it more easily, or even be able to get to its nutritional part, thus their beaks started to change in accordance to their food preference.
The rate for a recessive allele to decline to half its initial frequency will depend on the presence of selective evolutionary forces and random mating.
<h3>What is recessive allele frequency?</h3>
The recessive allele frequency refers to the initial frequency of a recessive allele in a population, which is masked in heterozygous individuals.
The recessive allele frequency depends on the adaptive fitness of this gene variant, the presence of selective forces and random mating, that facet its rate of change.
In conclusion, the rate for a recessive allele to decline to half its initial frequency will depend on the presence of selective evolutionary forces and random mating.
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There could be several orgins
Answer:
Although elephants and hyraxes at first don't seem to have many similarities, a closer look has led many scientists to believe that these animals are evolutionarily closely related.
Elephants and Hyraxes share many reproductive characteristics that indicate a common ancestor: The location of the testicules in these animals diverges from most mammalian species, remaining inside the retroperitoneal abdomen. Females have similar placental origins and long gestation periods and the location of the mammary glands in both orders (above the front legs) is a unique feature among non-primate mammals. Hyraxes' tusks develop from incisor teeth, similar to elephants, and in both cases nails develop into flattened, hoof-like structures.
Molecular evidence has also been used to confirm the hypothesis of evolutionary relatedness between the two orders, as similarities in some gene sequences in mitochondrial DNA and other molecular components. Both animals have some physiological similarities and cognitive characteristics (such as the presence of a powerful long-term memory) that support the possibility of evolutionary proximity.
The fossil record indicates that in the Eocene period hyraxes were dominant herbivores in Africa, with several species, reaching much larger sizes than today and occupying different ecological niches, indicating that elephants and hyraxes may have been very similar millions of years ago.
