First: Define evolution and natural selection _NATURAL SELECTION_____ is the process in which changes in an environment pressure a species to change. _EVOLUTION_______________ is the process in which traits caused by mutations slowly accumulate in a population over time.

How do organisms respond to environmental change? One way that some freshwater organisms respond to environmental change is to evolve rapidly. A marked change in the environment favors some characteristics of plants, animals and microbes over others.

In evolutionary theory, adaptation is the biological mechanism by which organisms adjust to new environments or to changes in their current environment. Organisms can adapt to an environment in different ways. They can adapt biologically, meaning they alter body functions.

When the environment changes, populations will often undergo directional selection (Figure 1b), which selects for phenotypes at one end of the spectrum of existing variation.

Natural selection is a simple mechanism that causes populations of living things to change over time. In fact, it is so simple that it can be broken down into five basic steps, abbreviated here as VISTA: Variation, Inheritance, Selection, Time and Adaptation.

Genetic drift is a mechanism of evolution. It refers to random fluctuations in the frequencies of alleles from generation to generation due to chance events. Genetic drift can cause traits to be dominant or disappear from a population.

A mutation is a change in an organism’s DNA. Mutations may instantly introduce a new allele into a population, causing small but intermediate shifts in allele and genotype frequencies. Because mutations are the ultimate source of all genetic variation, they collectively are extremely powerful in influencing evolution.

So, the correct answer is ‘An earthquake kills 90% of all the long flashing fireflies in a population of long, medium, and short flashing fireflies’