Chapter 5 Checkpoints Joseph Chen

How are artificial and natural selection similar? How are they different?

Artificial selection is by human intervention while natural selection is, to say, natural. However, they both are done so that a more favorable trait would become common within a population.

Why is it challenging to determine the number of species on earth?

Calculating the exact number of species is very difficult as species tend to vary in characteristics. Some species may require a microscope to see, some species may be nocturnal and some species may be living in unaccessible areas, such as the deep blue ocean.

How does environmental change determine species distribution? When does it lead to extinction?

Environmental change may cause a species' distribution to change as well if the species cannot adapt to the new conditions. When there is no favorable environment that is geographically close enough to move on, the species is likely to become extinct. Even if there is a favorable environment, it may be occupied by other superior species.

Why are estimates of species diversity valuable to environmental scientists?

Environmental scientists are able to find the species evenness and richness of a particular area from its estimates of species diversity.

What is evolution, and what are the three main ways in which it occurs?

Evolution is the change in a population's genetic composition over time. The three main ways in which evolution occurs are by artificial selection, by natural selection, and by random processes.

How do fundamental niches and realized niches differ?

Fundamental niches are the conditions that are ideal for a species while realized niches are the actually conditions a species is living in.

How does geographic isolation lead to reproductive isolation?

Geographic isolation is the physical separation of a species. The separated species will adapt to its new climate, thus becoming genetically different. As more time passes, the species will change into more distinct species until they also separated by reproductive isolation

How are human activities affecting extinction rates, and why is their impact a particular concern?

Human activities is affecting extinction rates quite negatively. Sure we have saved a few endangered species, but it was because of us they were endangered. In addition, we humans have killed off many species. Enough to define this time period as the 6th mass extinction. If we continue our path of destruction, the biodiversity in the world will lessen quickly. Our impact is a concern as 99 percent of species threatened by extinction is caused by our actions.

Why is the pace of human-driven evolution faster than that of natural evolutionary processes?

Human-driven evolution is faster than that of natural evolutionary processes since inserting a gene into an organism is much faster than traditional breeding.

What factors influence a species' chances of adapting successfully to a change in its environment?

Rate of environmental change, genetic variation, population size, and generation time are factors that influence a species' chances of adapting successfully to a change in its environment.

What is the difference between species richness and species evenness? Why are they both important measures?

Species richness measures the number of different species while species evenness tells whether the ecosystem has a dominant species or has similar abundances of all species. Both measures is needed to evaluate the biodiversity of an ecosystem.