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This information is meant to help college students and prospective biologists to review for key concepts in Biology.The information is also great for 200 level Biology students. The information emphasizes on evolution, the evolution of populations, the origin of species (or speciation), systematics, taxonomy, and phylogenies.

Selection

This is broadly defined as the survival of "fit" alleles in a population based on certain factors, such as sexual attractiveness, phenotype (morphology), behaviors, and environmental factors.

Evolution

This is considered to be a change in the allele frequency or a change in genetic variation of a population over time. Darwin referred to this concept as "descent with modification".

Hardy-Weinberg Principle (or Equilibrium)

This concept has been reached when a population is large, mating is random, no selection of any kind occurs, no mutations occur in the genetic structure, and no migration occurs.

Allele

This is a specific expression for a gene.

Genetic Drift

This is the fluctuation in the allele frequency of a population due to chance events. It especially has a greater impact on smaller populations.

Bottleneck Effect

This occurs when a population suffers heavy loss of life and experiences a drop in genetic variation.

Polyploidy

This condition is best described as an increase in chromosome sets.

Allopolyploidy

This is the result of interspecific breeding between two species where prezygotic barriers are absent, primarily in closely related yet distinct species. This phenomenon is also accountable for the sterility commonly found in the offspring. (i.e. donkeys are an example.)

Behavioral Isolation

This kind of prezygotic barrier has specific mating rituals and/or behaviors that will be performed by populations of the same species.

Allopatric Speciation

This form of speciation involves the geographic separation of a population.

Binomial Nomenclature

This is best described as the shortened, two-part name of a species.

Species

This is the smallest unit in the classification of living organisms.

Systematic

Species classification (phylogenetics) comprises taxonomy and evolutionary relationships. Since it involves classifying in a universal manner, phylogenetics can be thought of as far-reaching or ______.

Industrial Melanism

Human activities, particularly industrial processes, can affect the allele frequency and appearance of a population of a species. What is the term used to describe this particular phenomenon?

Allele Frequency

The number of times an allele can be found in a given population is known as what?

Mutation

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?

Evolution

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.

Artificial Selection

Otherwise known as "selective breeding", this kind of selection includes the domestication of plants, pets, and cattle.

Punctuated Equilibrium

This theory proposes that evolution can occur in a short period of time even after a relatively long period of absent evolutionary forces (genetic drift, mutation, selection...). (two words)

Clade

This term refers to the complete set of species descended from a common ancestor. It is otherwise known as a monophyletic taxon.

Polyphyletic Taxon

This kind of taxon can be misleading, as it compares species that do not have the same most recent common ancestor. It groups organisms primarily by homology.

Synapomorphy

This is kind of trait is only found in the descendants of a common ancestor.

Symplesiomorphy

This is an ancestral trait found in the common ancestor and two or more unrelated taxa (descendant species). The shared trait does not reflect a direct relationship between the descendant species or, more commonly, descendant clades.

Biological Species Concept

This species concept defines species as a single unit (species) capable of mating and producing viable offspring with only their own species. It also considers how appearance may deceive someone from correctly identifying species since species can contain individuals with different appearances.

Paraphyletic Taxon

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.

Homology

This term is used mostly to describe shared or similar physical and/or genetic characteristics found in unrelated or even closely related species.

Comparative Embryology

Among different species, there are similarities in embryo appearance and anatomy. This concept supports the theory of evolution by analyzing embryos of different species.

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.

Phylogenetic Species Concept

A species defined using this model - even if it has subspecies with slightly different phenologies - will include all subspecies since they all share a common ancestor and are capable of breeding and producing viable offspring.

Sympatric Speciation

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.

Secondary Contact

This happens when two geographically separated populations are reintroduced.

Mechanical Isolation

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.

Intersexual Selection

This kind of selective 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.

Archipelago

This kind of geographical landmass is a group of tight-knit islands, and it is ideal for evolution by way of isolation.

Natural Selection

This mechanism of change cannot venture away from the laws of nature since it is directed by an organism's environment. It is also limited to the alleles present for a specific trait. In other words, if genes for wing development are not present in a species, the species will not be able to fly due to environmental and, consequently, biological limitations.

Infanticide

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.

Gene Pool

This term provides a symbolic account for the diversity of genotypes and phenotypes in a population by depicting said diversity as a collection. It is increased by gene flow, mutation, and selective mating, among other genetically-oriented forces.

Epistasis

This phenomenom allows certain alleles to be expressed over other alleles for the same gene in the genotype of an individual.

Temporal Isolation

This kind of Prezygotic Barrier prevents closely related species from producing hybrid offspring in sympatric evolution due to different mating times.

Deoxyribonucleic Acid (DNA)

This macromolecule is responsible for heritability and for the genetic information in all living organisms.

Convergent Evolution

This is the emergence of like traits in different species. The emergence usually occurs within the same time frame and is also associated with likeness in environmental habitat.

Stratum

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.

Erosion

The remains of ancient lifeforms (fossils) are exposed to earth's surface by this.

Fossil

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.

Intrasexual Selection

This form of sexual selection involves the ability to compete 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.

Parsimony

This term is best described as the simplest explanation for an observed phenomenon. In this case, the debated evolutionary history of a group of organisms will likely be explained by the simplest explanation.

Alfred Russel Wallace

He was a British naturalist at the time Charles Darwin was developing his theory on evolution. Ironically, this man was also investigating on the same subject, and he urged Darwin to make his views heard. He is known as Darwin's right-hand man.

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