Bottleneck Effect

This is a picture of beads in a bottle being poured out. The beads in the bottle represent a population an its gene pool. The beads remaining in the bottle represent the population and its gene pool remaining after a sudden event in the environment, such as a flood. This drastic reduction in population size due to an environmental event can cause the bottleneck effect. By chance, some alleles may be overrepresented, underrepresented, or even completely absent in the remaining population gene pool. In other words, a bottleneck can significantly reduce a populations genetic variation. Reduced genetic variation means that the population may not be able to adapt to new selection pressures, because the genetic variation that selection would act on may be out of the population. After a bottleneck effect, genetic drift will most likely have these effects on the gene pool until the population becomes large enough so that chance events have less of an impact.  

Artificial Selection

This is a picture of broccoli. Broccoli has been cultivated from wild mustard through artificial selection. Artificial selection is a selection process in which evolution can occur. Humans have modified species, since before Darwin and Wallace, over many generations by selecting and breeding individuals that possess desired traits. An example is with how farmers and breeders have caused evolution in farm stock by only allowing plants and animals with desirable characteristics to reproduce. This process is called artificial selection because people, instead of nature, select which organisms are "better suited" to survive and reproduce.

Gene

This is a picture of an eye, featuring its blue coloration. Eye color is an example of a phenotype, or physical characteristic, determined by genes. A gene is a unit of heredity that is passed from parent to offspring. It is a specific locus, or location, on a strand of DNA, in which the nucleotide sequencing encodes a functional RNA or protein product. Protein synthesis is what determines physical characteristics. Most biological traits are influenced by polygenes, or many different genes.

Data

This is a picture of graph paper. Graph paper can be used to collect, organize, and/or analyze data. Data is a set of quantitative or qualitative observations. In other words, it is various pieces of information such as numbers, measurements, words, or descriptions of things. Data is analyzed through graphs or images to find a conclusion of what the data means.  

Vestigial Structure

This is a picture of a penguin. Penguin "wings" are considered a vestigial structure. A vestigial structure is a structure, or organ, that has seemed to have lost all, or most, of its functions over time through the process of evolution. They provide clues to the evolutionary history of species, because they are the remnants of structures seen in ancestral species. The wings of flightless birds, such as penguins, are vestigial structures since the evolutionary function of the wing structure was to fly. Penguins use their wings to swim; not for flight.

Asexual Reproduction

This is a picture of a star fish. Starfish have the ability to reproduce asexually. Asexual reproduction is when one individual produces, using mitosis, offspring that are genetically identical to itself. It can occur as budding, fission, or spore formation, not involving the fusion of gametes. Asexual reproduction is the primary form of reproduction for single-celled organisms such as the archaebacteria, eubacteria, and protists. There are also many invertebrates, including sea anemones and sea stars, that produce by asexual reproduction.

Hermephrodite

This is a picture of a clown fish. A clown fish is an example of a hermaphrodite, an organism that has reproductive organs associated with both male and female sexes. Many groups of organisms, mostly invertebrates, do not have separate sexes. Some hermaphrodite organisms can self-fertilize, while others require a partner. Examples of hermaphrodite organisms include snails, echinoderms such as sea stars, worms, and many species of fish such as wrasse and parrot fish. A clown fish is a protogynous hermaphrodite, meaning they first function as females and then later as males.