Term
|
Definition
| Referring to any mutation, allele, or trait that reduces an individual's fitness. |
|
|
Term
|
Definition
| Allele that determines the phenotype of a heterozygous individual. |
|
|
Term
|
Definition
| The process by which individuals with certain heritable trais tend to produce more surviving offspring than do individuals without those traits, often leading to a change in the genetic makeup of the population. A major mechanism of evolution. |
|
|
Term
|
Definition
(1) The theory that all organisms on Earth are related by common ancestry and that they have changed over time, predominantly via natural selection.
(2) Any change in the genetic characteristics of a population over time, especially, a change in allele frequencies. |
|
|
Term
|
Definition
| Consists of individuals of the same species that are living in the same area at the same time. |
|
|
Term
| Descent with Modification |
|
Definition
| The phrase used by Darwin to describe his hypothesis of evolution by natural selection. |
|
|
Term
|
Definition
|
|
Term
|
Definition
Any change in the hereditary material of an organism (DNA in most organisms, RNA in some viruses). It's the ONLY source of new alleles. |
|
|
Term
|
Definition
| In population genetics, movement of individuals from one population to another. |
|
|
Term
|
Definition
| Any change in allele frequencies due to random events. Causes allele frequencies to drift up and down randomly over time, and eventually can lead to the fixation or loss of alleles. |
|
|
Term
|
Definition
The movement of alleles between populations; occurs when individuals leave one population, join another, and breed.
- Effect on overall genetic diversity depends
- Changes allele frequencies
- The impact on fitness is random
|
|
|
Term
|
Definition
| Mating between closely related individuals. Increases homozygosity of a population and often leads to a decline in the average fitness (inbreeding depression). |
|
|
Term
|
Definition
In evolutionary biology, an inescapable compromise between two traits that cannot be optimized simultaneously. |
|
|
Term
|
Definition
If directional selection continues over time, the favored alleles will eventually approach a frequency of 1.0 while disadvantageous alleles will approach a frequency of 00. Alleles that reach a frequency of 1.0 are said to be... |
|
|
Term
|
Definition
| The long-accepted hypothesis that information in cells flows in one direction: DNA codes for RNA, which codes for proteins. |
|
|
Term
|
Definition
A pattern of natural selection that favors one extreme phenotype with the result that the average phenotype of a population changes in one direction. Generally reduces overall genetic variation in a population. |
|
|
Term
|
Definition
| All of the alleles of all of the genes in a certain population. |
|
|
Term
|
Definition
A pattern of natural selection that favors phenotypes near the middle of the range of phenotypic variation. Reduces overall genetic variation in a population.
decreases overall genetic diversity
changes allele frequencies
increases fitness |
|
|
Term
|
Definition
| A pattern of natural selection that favors extreme phenotypes at both ends of the range of phenotypic variation. Maintains overall genetic variation in a population. |
|
|
Term
|
Definition
A pattern of natural selection that favors heterozygous individuals compared with homozygotes. Tends to maintain genetic variation in a population. |
|
|
Term
|
Definition
A pattern of natural selection in which no single allele is favored in all populations of a species at all times. Instead, there is a balance among alleles in terms of fitness and frequency. |
|
|
Term
|
Definition
A change in allele frequencies that often occurs when a new population is established from a small group of individuals (founder event) due to sampling error (i.e. the small group is not a representative sample of the source population). |
|
|
Term
|
Definition
A reduction in allelic diversity resulting from a sudden reduction in the size of a large population (population bottleneck) due to a random event. |
|
|
Term
|
Definition
| One of a class of enzymes that catalyze synthesis of RNA from ribonucleotides using a DNA template. |
|
|
Term
|
Definition
| An RNA molecule that carries encoded information, transcribed from DNA, that specifies the amino acid sequence of a polypeptide. |
|
|
Term
|
Definition
| The set of all 64 codons and the particular amino acids that each specifies. |
|
|
Term
|
Definition
| A sequence of three nucleotides in DNA or RNA that codes for a certain amino acid or that initiates or terminates protein synthesis. |
|
|
Term
|
Definition
| The division of a sequence of DNA or RNA into a particular series of three-nucleotide codons. There are three possible reading frames for any sequence. |
|
|
Term
|
Definition
| The AUG triplet in mRNA at which protein synthesis begins; codes for the amino acid methionine. |
|
|
Term
|
Definition
| One of three mRNA triplets (UAG, UGA, or UAA) that cause termination of protein synthesis. |
|
|
Term
|
Definition
| A mutation that results in a change in a single nucleotide pair in a DNA molecule. |
|
|
Term
|
Definition
| The state of having more than two full sets of chromosomes. |
|
|
Term
|
Definition
| The state of having an abnormal number of copies of a certain chromosome. |
|
|
Term
|
Definition
| A mutation in which a segment of a chromosome breaks from the rest of the chromosome, flips, and rejoins with opposite orientation as before. |
|
|
Term
|
Definition
| A point mutation that causes a change in the amino acid sequence of a protein. |
|
|
Term
|
Definition
| A mutation that does not detectably affect the phenotype of the organism. |
|
|
Term
|
Definition
| Any chromosome that does not carry genes involved in determining the sex of an individual. |
|
|
Term
|
Definition
| The inheritance patterns that occur when genes are located on autosomes rather than on sex chromosomes. |
|
|
Term
|
Definition
| Genes located on sex chromosomes. Patterns of inheritance in males and females differ. |
|
|
Term
|
Definition
| Two genes found on the same chromosome. Linked genes violate the Principle of Independent Assortment. |
|
|
Term
|
Definition
| Heterozygotes have intermediate phenotype. Polymorphis - heterozygotes have unique phenotype. |
|
|
Term
|
Definition
| Heterozygotes have phenotype of both alleles. |
|
|
Term
|
Definition
| In a population, more than two alleles present at a locus. |
|
|
Term
|
Definition
| In a population, more than two alleles present at a locus. |
|
|
Term
|
Definition
| In a population, more than two phenotypes associated with a single gene are present. |
|
|
Term
|
Definition
| A single allele affects many traits. |
|
|
Term
|
Definition
| In discrete traits, the phenotype associated with an allele depends on which alleles are present at another gene. |
|
|
Term
| Gene-by-environment Interaction |
|
Definition
| Phenotype influenced by environment experienced by individual. |
|
|
Term
|
Definition
| A family tree of parents and offspring, showing inheritance of particular traits of interest. |
|
|
Term
|
Definition
| In general, a recessive phenotype should show up in offspring ONLY when both parents have that recessive allele and pass it on to their offspring. |
|
|
Term
|
Definition
| Allele that appears in every male that carries it. The appearance of the trait skips a generation in a pedigree. |
|
|
Term
| The Principle of Independent Assortment |
|
Definition
| The concept that each pair of hereditary elements (alleles of the same gene) behaves independently of other genes during meiosis. Variation AMONG chromosomes. |
|
|
Term
|
Definition
| A change in the combination of genes or alleles on a given chromosome or in a given individual. Variation WITHIN chromosomes. |
|
|
Term
|
Definition
| Selection that lowers the frequency or even eliminates deleterious alleles. |
|
|
Term
|
Definition
| If directional selection continues over time, the favored alleles will eventually approach a frequency of 1.0 while disadvantageous alleles will approach a frequency of 0.0. The alleles that reach a frequency of 0.0 are said to be... |
|
|
Term
|
Definition
| Variation that is only good when the environment is changing. |
|
|
Term
| Temporal Reproductive Isolation |
|
Definition
| Populations are isolated because they breed at different times. |
|
|
Term
| Habitat Reproductive Isolation |
|
Definition
| Populations are isolated because they breed in different habitats. |
|
|
Term
| Behavioral Reproductive Isolation |
|
Definition
| Populations do not interbreed because their courtship displays differ. |
|
|
Term
| Gametic barrier Reproductive Isolation |
|
Definition
| Matings fail because eggs and sperm are incompatible. |
|
|
Term
| Mechanical Reproductive Isolation |
|
Definition
| Matings fail because male and female reproductive structures are incompatible. |
|
|
Term
|
Definition
| Hybrid offspring do not develop normally and die as embryos. |
|
|
Term
|
Definition
| Hybrid offspring mature but are sterile as adults. |
|
|
Term
| Phylogenetic species concept |
|
Definition
| The definition of a species as the smallest monophyletic group in a phylogenetic tree. |
|
|
Term
|
Definition
| An evolutionary unit that includes an ancestral population and all of its descendants and no others. |
|
|
Term
|
Definition
| A shared, derived trait found in two or more taxa that is present in their most recent common ancestor but is missing in more distant ancestors. Useful for inferring evolutionary relationships. |
|
|
Term
| Biological Species Concepts |
|
Definition
Reproductive isolation between populations (they don't breed and don't produce viable offspring).
Advantages: Reproductive isolation = evolutionary independence.
Disadvantages: Not applicable to asexual or fossil species; difficult to assess if populations do not overlap geographically. |
|
|
Term
|
Definition
Morphologically distinct populations.
Advantages: Widely applicable
Disadvantages: Subjective; misses cryptic species |
|
|
Term
|
Definition
Smallest monophyletic group on phylogenetic tree.
Advantages: widely applicable; based on testable criteria
Disadvantages: Relatively few well-estimated phylogenies are currently available. |
|
|
Term
|
Definition
| The physical splitting of a population into smaller, isolated populations by a geographic barrier. |
|
|
Term
|
Definition
| Categorical versus categorical. |
|
|
Term
|
Definition
|
|
Term
|
Definition
| Continuous versus continuous. |
|
|
Term
|
Definition
Increases homozygosity and does not cause evolution, because allele frequencies do not change in the population as a whole.
- As no effect on overal genetic diversity
- No impact on fitness
- Changes genotype frequencies - not allele frequencies
|
|
|
Term
|
Definition
| In inbred offspring, fitness declines due to deleterious recessive alleles that are homozygous. |
|
|
Term
|
Definition
| The independent evolution of analogous traits in distantly related organisms due to adaptation to similar environments and similar way of life. |
|
|
