Understanding:
5.1.U6: Continuous variation across the geographical range of related populations matches the concept of gradual divergence. Objective:
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The degree of divergence between geographically separated populations will gradually increase the longer they are separated. As the genetic divergence between the related populations increase, their genetic compatibility consequently decreases. Eventually, the two populations will diverge to an extent where they can no longer interbreed if returned to a shared environment. This process is called speciation.
- When populations diverge over time and are separated, one would expect these populations to be in different stages of variation or divergence and not all separate distinct organisms right away or all the same unchanged species
- Darwin gave many of these examples that showed populations that are slightly different, but are not clearly separate species
- Examples of this are the Lava lizards and finches of Galapagos, and the Spiny Sticklebacks of BC
Biogeography is the study of species distributions. It examines how species have been distributed across different places at different times. The distribution of species shows a very clear pattern. More similar species tend to be found closer to one another geographically. The distribution of many animals and plants across different continents can be explained by continental drift (the movement tectonic plates).
Understanding:
5.1.U5: Populations of a species can gradually diverge into separate species by evolution.
Objective:
Describe the process of gradual speciation.
5.1.U5: Populations of a species can gradually diverge into separate species by evolution.
Objective:
Describe the process of gradual speciation.
Within a population of any given species there will be genetic variation (i.e. variation which is inheritable). Typically this variation will be continuous and follow a normal distribution curve as the rate of change is gradual and cumulative
- Within a population there is genetic variation
- If two populations of the same species become separated so that they do not reproduce or interbreed because they become separated by geographical boundaries; for example one group migrates to an island or they became separated by a mountain range, then natural selection will act differently on those two separate populations
- Over time, these populations change so that they are recognizably different and can or do not interbreed if they were to merge together again
- The evolutionary process by which two related populations diverge into separate species is called speciation
Speciation via Divergent Evolution