Term
|
Definition
| Single gene effects muliple phenotypes |
|
|
Term
|
Definition
| A gene at one locus alters the phenotypic expression of a gene at a second locus. |
|
|
Term
| Quantitative Characters (pg 263) |
|
Definition
| For many characters (skin color or human height for example) and either-or classification is impossible becaue the characters vary in the population along a continuum (in gradations). These are called quantitative characters. |
|
|
Term
| Polygenic Inheritance (pg 263) |
|
Definition
An additive effect of two or more genes on a single phenotypic character. Ex. Genes A, B, and C all effect the darkness of skin. ... Look at pg 263 for more |
|
|
Term
Norm of Reaction (for a phenotype) pg 264 |
|
Definition
| A genotype is not generally associated with a rigidly defined phenotype, but rather with a range of phenotypic possibilities due to environmental influences. This phenotypic range is called the norm of reaction. |
|
|
Term
|
Definition
| Many factors, both genetic and environmental, collectively influence phenotype. |
|
|
Term
|
Definition
| The members of a pair of homologous chromosomes do not move apart properly during meiosis one or sister chromatids fail to separate during meiosis two. In these cases, one gamete recieves two of the same type of chromosome and another gamete recieves no copy. |
|
|
Term
|
Definition
If either of the aberrant gametes formed from nondisjunction unites with a normal one at fertilization, the offspring will have an abnormal number of a particular chromosome, a condition known as aneuploidy. trisomic = 2n+1 chromosomes monosomic = 2n-1 chromosomes |
|
|
Term
|
Definition
An organisn having more than two complete chromosome sets. triploidy = 3n = 3 chromosomal sets tetraploidy = 4n = 4 chromosomal sets |
|
|
Term
| Alterations of Chromosome Structure (pg 286) |
|
Definition
Deletion- removes a chromosomal segment Duplication (harmfull)- repeats a segment Inversion- reverses a segment within a chromosome translocation (harmfull when not reciprical)- moves a segment from one chromosome to another, nonhomologous one. |
|
|
Term
| Genomic Imprinting (pg 288) |
|
Definition
| Variation in phenotype depending on whether an allele is inherited from the male or female parent. |
|
|
Term
|
Definition
Changes in the gentic material of a cell. "Changes in the nucleotide sequence of DNA." |
|
|
Term
|
Definition
chemical changes in just one base pair of a gene. Types = base-pair substitutions -missnese mutations -nonsense mutations -frameshift mutations |
|
|
Term
| base-pair substitutions (pg 328) |
|
Definition
the replacement of one nucleotide and its partner with another pair of nucleotides. Some substitutions are called silent mutations because they have noe effect on the encoded protein. In other words, a change in a base pair may transform one codon into another that is translated into the same amino acid. |
|
|
Term
| missense mutations (pg 328) |
|
Definition
| Substitution mutations are usually missense mutations, that is, the altered codon still codes for an amino acid and thus makes sense, although not necessarily the right sense. |
|
|
Term
| nonesense mutation (pg 328) |
|
Definition
A point mutation that changes a codon for an amino acid into a stop codon. THis causes translation to be terminated prematurely. The resulting polypeptide will be shorter than the polypeptide encoded by the normal gene. |
|
|
Term
| Frameshift Mutation (pg 329) |
|
Definition
Occurs whenever the number of nucleotides inserted or deleted is not a multiple of three. All of the nucleotides that are downstream of the deletion or insertion will be improperly grouped into codons, and the result will be extensive missense probably ending sooner or later in nonesense and premature termination. Almost always produces a nonfunctional protein. |
|
|
Term
|
Definition
| Physical and chemical agents that interact wth DNA in ways that cause mutations. |
|
|
Term
| Population Genetics (pg 455) |
|
Definition
| The study of how populations change genetically over time. |
|
|
Term
|
Definition
| The aggregate of genes in a population at any one time is called the populations gene pool. It consists of all alleles at all gene loci in all individuals of the population. |
|
|
Term
| Hardy-Weinberg theorem (pg 456) |
|
Definition
| The frequencies of alleles and genotypes in a population's gene pool remain constant from generation to generation, provided that only Mendelian segregation and recombination of alleles are at work. |
|
|
Term
Conditions for Hardy-Weinberg Equilibrium (pg 458) |
|
Definition
1: Extremely large population size 2: No migration (transfer of alleles between populations) 3: No mutations 4:Random mating 5: No natural selection |
|
|
Term
|
Definition
The fraction of phenotypic variation accounted for by genetic differences. Also the slope of the parent-offspring regression. h2 = Vg / Vp |
|
|
Term
|
Definition
p = f(A) This is the frequency of the (A) allele. Also equals f(AA) + 1/2 * f(Aa) |
|
|
Term
|
Definition
p2 = f(AA) p2 equals the frequency of the (AA) genotype. |
|
|
Term
|
Definition
2pq = f(Aa) 2pq equals the frequency of the (Aa) genotype. |
|
|
Term
|
Definition
q2 = f(aa) q2 equals the frequency of the (aa) genotype. |
|
|
Term
|
Definition
Unpredictable fluctuations in allele frequencies from one generation to the next because of a populations finite size. -Results in evolution -more important evolutionary force in smaller populations. -Does not lead to complexity, adaptation |
|
|
Term
| Bottleneck Effect (pg 461) |
|
Definition
A sudden change in the environment, such as a fire or flood, may drastically reduce the size of a population. In effect, the survivors have passed through a restrictive "bottleneck" and their gene pool may no longer be reflective of the original population's gene pool. By chance, certain alleles may be overrepresented among the survivors, others may be underrepresented, and some may be eliminated altogether. -Reduces genetic diversity -Loss of rare alleles |
|
|
Term
|
Definition
| When a few individuals become isolated from a larger population, this smaller group may establish a new population whose gene pool is not reflective of the source population. |
|
|
Term
|
Definition
| Genetic additions to and/or subtractions from a population resulting from the movement of fertile individuals or gametes. |
|
|
Term
| Modes of Selection (pg 465) |
|
Definition
-directional selection -disruptive selection -stabilizing selection |
|
|
Term
directional selection (pg 465) |
|
Definition
Shifts the overall makeup of the population by favoring variants at one extreme of the distribution. For example, darker mice might be favored because they live among dark rocks, and a darker fur color conceals them from predators. |
|
|
Term
disruptive selection (pg 466) |
|
Definition
Favors variants at both ends of the distribution. For example, mice with both dark and light coats are favored because they have colonized a patchy habitat made up of light and dark rocks, with the result that mice of an intermediate color are at a disadvantage. |
|
|
Term
stabalizing selection (pg 466) |
|
Definition
| Removes extreme variants from the population and preserves intermediate types. If the environment consists of rocks of an intermediate color, both light and dark mice will be selected against. |
|
|
Term
balancing selection/balanced polymorphism (pg 466) |
|
Definition
| Balancing selection occurs when natural selection maintains stable frequencies of two or more phenotypic forms in a population, a state called balanced polymorphism. |
|
|
Term
| heterozygote advantage (pg 466) |
|
Definition
| If individuals who are heterozygous at a particular gene locus have greater fitness than the homozygotes, natural selection will tend to maintain two or more alleles at that locus. |
|
|
Term
| frequency-dependent selection (pg 467) |
|
Definition
The fitness of any one morph declines if it becomes too common in the population. Ex: Rare moths of any pattern were at an advantage and common moths of any pattern were at a disadvntage because birds learned to find the common moths more easily than the rare ones. This preserves polymophism in populations. |
|
|
Term
| neutral variation (pg 468) |
|
Definition
| Variation that confer no selective advantage. |
|
|
Term
|
Definition
| Genes that have become inactivated by mutations. |
|
|
Term
| Intrasexual selection (pg 468) |
|
Definition
| Selection within the same sex. A direct competition among individuals of one sex for mates of the opposite sex. |
|
|
Term
| Intersexual selection (pg 468) |
|
Definition
| Individuals of one sex (usually females) are choosy in selecting mates from the other sex. |
|
|
Term
| Why can't natural selection fashion perfect organisms? (pg 470) |
|
Definition
1: evolution is limited by historical restraints 2: Adaptations are often compromises 3:Chance and natural selection interact 4:Selection can edit only existing variations |
|
|
Term
|
Definition
| When animals behave in ways that reduce their individual fitness but increase the fitness of other individuals in the population. |
|
|
Term
| Inclusive Fitness (pg 1129) |
|
Definition
| The total effect an individual has on proliferating its genes by producing its own offspring and by providing aid that enables other close relatives, who share many of those genes, to produce offspring. |
|
|
Term
|
Definition
| Natural selection that favors altruistic behavior by enhancing reproductive success of relatives. |
|
|
Term
| Reciprocal Altruism (pg 1130) |
|
Definition
| When an animal behaves altruistically towards other animals who are not related. This occurs because the favor is hoped to be returned in the future. |
|
|
Term
|
Definition
p' = p - p * u Where: p' = p after mutation p = p before mutation u = mutation rate in mutations/allele/generation |
|
|
Term
|
Definition
| Males and females with like phenotype tend to mate with each other. |
|
|
Term
| biological species concept (pg 473) |
|
Definition
| Defines a species as a population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but are unable to produce viable, fertile offspring with members of other populations. |
|
|
Term
| reproductive isolation (pg 473) |
|
Definition
| The existence of biological factors (barriers) that impede members of two species from producing viable, fertile hybrids. |
|
|
Term
| prezygotic barriers "before the zygote" (pg 473) |
|
Definition
| These impede mating between species or hinder the fertilization of ova if members of different species attempt to mate. |
|
|
Term
| postzygotic barriers (pg 473) |
|
Definition
| Prevent the hybrid zygote from developing into a viable, fertile adult. |
|
|
Term
| morphological species concept (pg 476) |
|
Definition
| Characterizes a species by its body shape, size, and other structural features. |
|
|
Term
| paleontological species concept (pg 476) |
|
Definition
| Morphologically discrete species known only from the fossil record. |
|
|
Term
ecological species concept (pg 476) |
|
Definition
| Views a species in terms of its ecological niche, its role in a biological community. |
|
|
Term
| phylogenetic species concept (pg 476) |
|
Definition
Defines a species as a set of organisms with a unique genetic history- that is, as one branch on the tree of life. |
|
|
Term
| allopatric speciation (pg 477) |
|
Definition
| Gene flow is interrupted when a population is divided into geographically isolated subpopulations. For example, the water level in a lake may subside, resulting in smaller lakes that are home to seperated populations. |
|
|
Term
|
Definition
| An individual that has more than two chromosome sets, all derived from a single species. |
|
|
Term
|
Definition
| A fertile polyploid that was once a sterile hybrid. |
|
|
Term
| adaptive radiation (pg 480) |
|
Definition
| The evolution of many diversly adapted species from a common ancestor upon introduction to various new environmental opportunities and challenges is called adaptive radiation. |
|
|
