Geographical isolation as one of the factors of evolution

Phd.Anna Zhukova
Created by- Darbar Raj Pravinkumar

a population of animals, plants, or other organisms that are separated from

exchanging genetic material with other organisms of the same species. Typically geographic isolation is the result of an accident or coincidence

experience unique pressures, they will adapt to their environment over

time and can eventually become very different from each other. This has the end result of speciation.
For example, if snails slowly travel beyond a big canyon, the snails on one side will adapt to that environment and the snails on the other side will do the same with their environment. On one side, dark shells might hide them from predators. On the other side, bright coloring might let them stay cool in strong sunlight.
Over time, the two populations become more genetically differentiated and might become two distinct species with independent geographic ranges.

by Barriers
Isolation by Distance
Isolation after an Event
Isolation by Separation

some degree from the rest of the world by water,

develop certain diseases due to the lack of genetic material from other ethnicities and races.
Physical barriers prevent fish from one stream from mating with fish from another stream, leading to a less varied gene pool among those fish. As time passes, the fish become unable to successfully mate with other groups.
A mountain range prevents two types of goat from mating, causing the gene pool to become less varied.

each other, resulting in a less varied gene pool.
Genetic interchange

between finches is prevented when a flock becomes isolated from the rest on an island. Eventually, the isolated group emerges as a completely separate species.
A group of genetically differentiated chimpanzees is unable to mate with any other chimpanzees outside of their group due to physical isolation, leading to the development of certain diseases that genetic material from the other chimpanzees would have prevented.
A group of genetically differentiated bottlenose dolphins is separated from other members of its species and eventually goes extinct.

separate from each other. Over time, each species experiences genetic

makeup specific only to their own smaller, less diverse populations.
When a piece of land breaks off from a continent, the animals on the piece of land are only able to reproduce with their own populations. This results in the animals becoming entirely separate species over time.
Temporary isolation from a larger population of flies results in species behavior that causes a subgroup of flies not to mate with one another. When the subgroup joins the larger group, the two are now unable to produce fertile offspring.
A forest fire causes the permanent separation of a group of deer from their native population, causing the small group to interbreed only with one another. Over time, the group becomes an entirely different species.

only work, eat and mate with one another. As a

result, only genetic material within that small group is exchanged, leading to a less varied beetle population than others that mate with different subgroups.
A population of brown-haired people is separated from those with other hair colors and, as such, does not mix genetically with populations of any other hair color, leading to a population that is of homogenous brown hair color.
A small and isolated town contains individuals who do not marry anyone who was not raised in the town, resulting in a less diverse gene pool than a less homogenous population.

type of geographic event or object. This event or object

physically prevents two populations from being in the same area, preventing them from mating.
As an example, let's look at a species of fish. These fish are all members of the same species, though some fish happen to have green scales and others happen to have pink scales. All the fish live in the east of the river.
One day, strong rain caused the river to flood, and the currents in the river became overpowering, sweeping some fish to the west of the river. Once in the west, the fish were unable to get back to the east.

B. However, both groups are still members of the same

species. Since the two populations will never be reunited, eventually the ratio of green fish will increase in Population A, and the ratio of pink fish will increase in Population B. Over time, each population will only have one color.

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vulnerable to various disorders. It can be damaged by the

following:
Trauma
Infections
Degeneration
Structural defects
Tumors
Blood flow disruption
Autoimmune disorders
Disorders of

of a headache
A headache that changes or is different
Loss of

feeling or tingling
Weakness or loss of muscle strength
Loss of sight or double vision
Memory loss
Impaired mental ability
Lack of coordination
Muscle rigidity
Tremors and seizures
Back pain which radiates to the feet, toes, or other parts of the body
Muscle wasting and slurred speech
New language impairment (expression or comprehension)

disorders
Neurology
Neurological surgery
Neuroradiologists and interventional radiologists
Rehabilitation for neurological disorders

called neurology. The medical healthcare providers who treat nervous system disorders are called

neurologists. Some neurologists treat acute strokes and cerebral aneurysms using endovascular techniques.

care for patients with nervous system disorders is called physical

medicine and rehabilitation. Healthcare providers who work with patients in the rehabilitation process are called physiatrists.