Answer:
Species: is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction.
Alleles: one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.
Mutations: is a change in a DNA sequence. Mutations can result from DNA copying mistakes made during cell division, exposure to ionizing radiation, exposure to chemicals called mutagens, or infection by viruses.
Fitness: is the quantitative representation of natural and sexual selection within evolutionary biology.
Selective Pressures: are environmental factors or influences which may lessen reproduction in a species' population and therefore contributes to evolutionary change or even extinction through natural selection.
Explanation: Hope this helps and Have a nice of the rest of your day!