This is considered to be a change in the allele frequency or a change in genetic structure of a population over time. (Descent with modification).
Hardy-Weinberg Principle (or Equilibrium)
This concept has been reached when a population is large, mating is random, no selection occurs, no mutations occur in the genetic structure, no migration occurs, and no (natural) selection occurs.
This is the fluctuation in the allele frequency of a population due to chance events. It especially has a greater impact on smaller populations.
This occurs when a population suffers heavy loss of life and experiences a drop in genetic variation.
This is the result of interspecific breeding between two species, and it is accountable for the sterility of the offspring.
This kind of prezygotic barrier has specific mating rituals and/or behaviors that will be performed by populations of the same species.
Human activities consequentially affect the allele frequency and appearance of a population of a species.
Mechanisms for evolution influence the genotype and, possibly, the phenotype of a population. This exemplifies what?
This causes a change in an individual's DNA sequence. It may or may not be beneficial to the individual, but is the ultimate source for evolution.
Biogeographical evidence and Direct Observation of Change
When Darwin traveled around the world on the H.M.S. Beagle, he discovered a vast array of finch species living on the Galapogos Islands. These finches provided what two kinds of evidence for evolution?
Otherwise known as selective breeding, this kind of selection includes the domestication of plants, pets, and cattle.
This theory proposes that evolution occurs in a short period of time and that species do not change for long periods of time (remain in stasis).
This term refers to the complete set of species descended from a common ancestor. It is otherwise known as a monophyletic taxon.
This kind of taxon can be misleading, as it compares two or more different species with similar appearances.
Endler's Guppy Experiment
This experiment was conducted by a professor from California University in Santa Barbara, California. He studied a species of fish that were preyed upon by Pike cichlids and Killifish living in rivers in Trinidad, a Caribbean Island.
This is an ancestral trait that is found in the common ancestor and two or more unrelated taxa (descendant species).
Biological Species Concept
This species concept is best thought of as speciation through separation of gene pools and reproductive isolation.
This over-arching theme of life is not considered to be controlled by any one mechanism of change. It is also not considered to be progress or complexity or the preservation of species.
A taxon containing the common ancector of a chosen few descendants is considered to be this. (Think of chunking).
In cladisitics, it is more reliable than polyphyletic taxons. However, it is sparingly used by experienced taxonomists.
This term is used mostly to describe the analogous characteristics found in different species.
Among different species, there are similarities in embryo appearance and anatomy. This concept supports the theory of evolution.
Phylogenetic Species Concept
This species concept applies the shared original traits found in a collection of populations.
Unlike speciation by separation, this kind of speciation takes place when two populations of the same species exist in the same area. Reproduction and gene flow eventually taper off between the two populations, respectively.
This Prezygotic Barrier accounts for the prevention of mating by way of incongruous reproductive organs.
Peripherally Isolated Populations
This allopatric model is characterized by intermittent populations living outside the greater population density of a species.
This kind of reproductive behavior can best be described as the choice of the most attractive individual of the opposite sex in a population. The behavior is particularly common in females.
This kind of geographical landmass is a group of tight-knit islands, and it is ideal for evolution by way of isolation.
This mechanism of change cannot venture away from the laws of nature. It requires "raw" genetic material. In other words, pigs can't fly. If the mechanism could select a trait from scratch, the evolution of species would be discordant.
This kind of behavior is seen in new alpha male Langurs. The new male langur kills the offspring of the previous alpha male to increase the chances that only their offspring will succeed, thus increasing the fitness of the genes they put into the next generation of langurs.
This accounts for the diversity of genotypes and phenotypes in a population. It is increased by gene flow.
This phenomenom allows certain alleles to be expressed over other alleles for the same gene in the genotype of an individual.
This kind of Prezygotic Barrier prevents closely related species from producing hybrid offspring in sympatric evolution. The species mate at different times.
Deoxyribonucleic Acid (DNA)
This macromolecule is responsible for heritability and for the genetic information in all living organisms.
This kind of evolution is characterized by the appearance of the same trait in different species. The change occurs within the same time frame, and the change also occurs under the same prevailing environmental conditions.
This is a layer of earth that has characteristics different from most other layers. They are useful in examining the past history of the planet. Older layers are found farther in the earth's crust.
Ancient life is often discovered in this preserved state. It results from many years of heat and pressure in sediments beneath the earth's surface. Weathering and/or human activities bring them back to the surface.
This is the direct competition for a mate between members of the same sex, usually males.
Morphological Species Concept
This model is used to classify organisms with exact anatomical similarity.