Since the two groups are in their own unique ecosystems and each 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. When two populations of the same species are prevented from mating by a barrier or distance, they are experiencing geographic isolation. Barriers can be created by changing environments, like shifting mountains and rivers.
They can also be produced by natural disasters, like forest fires , earthquakes, and floods. Isolation stops the exchange of genetic material between the two populations. They start to evolve separately from each other because their environments are different. Differences in climate and food sources can create selective pressures unique to each population. Eventually, the two populations might become different species, but not always.
They all look different and utilize different food sources. As strange as it seems, this type of isolation can still happen in human populations. Particularly, this has happened with isolated tribes around the world.
For example, there is still a tribe in the Amazon that has not made contact with the rest of Brazil, much less the rest of the world. Although we know nothing about these people, we can only imagine that their allele frequencies and acquired mutations are very different from ours. Geographic isolation is an isolating mechanism in nature. Over long periods of time, it can lead to speciation. As the name suggests, it happens when populations of a species become separated, well, geographically.
This can be a physical barrier that prevents the organisms on either side from breeding like a mountain range or river , or it can even be a large distance between the two ends of the population's range. We'll call this cartoon face species "little dudes". The rectangle represents the range of their habitat. As you can see, there is some phenotypic variation in the little dudes' coloration.
Although the majority of the little dudes are purple, some are red and some are blue. In this hypothetical example, the different colors have no effect on an individual's fitness , so there's no particular selective pressure favoring any one phenotype. Immediately after the populations are split, the little dudes are still all the same species. Because they are one species, individual dudes from both sides could technically mate, if they were able to reach each other.
But because of the physical separation, they can't cross over, allowing the two populations' gene pools to drift apart. Now, imagine some time has passed. Why is isolation important to the formation of new species?
What is required for the formation of new species? What defines a new species? What are the 5 types of species interactions? What are the categories of species? How many orders are there in taxonomy? What is the order of life? What does order mean in classification? Who was given the term order? How order of reaction is determined?
Previous Article Why do we use control system? Next Article What are the two main steps of speciation? Back To Top. UC Berkeley. Geographic isolation In the fruit fly example, some fruit fly larvae were washed up on an island, and speciation started because populations were prevented from interbreeding by geographic isolation. Scientists think that geographic isolation is a common way for the process of speciation to begin: rivers change course, mountains rise, continents drift, organisms migrate, and what was once a continuous population is divided into two or more smaller populations.
Reduction of gene flow However, speciation might also happen in a population with no specific extrinsic barrier to gene flow. Imagine a situation in which a population extends over a broad geographic range, and mating throughout the population is not random.
Individuals in the far west would have zero chance of mating with individuals in the far eastern end of the range. So we have reduced gene flow, but not total isolation. This may or may not be sufficient to cause speciation.
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