Intro to genetics exam 2

Polygenic Inheritance

Multiple genes contribute to a single phenotype.

Epistasis

When the expression of one gene is dependent on another gene.

Codominance

A genetic scenario where neither allele is dominant or recessive, allowing both traits to be fully expressed.

Pleiotropy

When a single gene affects two or more phenotypic traits.

Sex-linked genes

Genes located on sex chromosomes (X & Y chromosomes), often resulting in certain traits being more common in one sex.

Homozygous

Having two identical alleles for a given gene.

Hemizygous

Having only one allele for a gene, as seen in males for genes on the X chromosome.

Mutation

A change in the DNA sequence that can lead to new traits.

Gene Flow

The transfer of alleles or genes from one population to another.

Genetic Drift

Random changes in allele frequencies in a population due to chance events.

Founder Effect

A loss of genetic diversity when a population is established by a very small number of individuals.

Bottleneck Effect

A sharp reduction in population size due to environmental events or human activities, leading to a loss of genetic diversity.

Natural Selection

The process by which individuals with favorable traits are more likely to reproduce.

Hardy-Weinberg Equilibrium

The condition under which a population's allele frequencies are constant over time.

Penetrance

The proportion of individuals with a particular genotype that exhibits the corresponding phenotype.

Expressivity

The degree to which a genotype is expressed in an individual.

Prezygotic barriers

Factors that prevent fertilization from occurring between different species.

Postzygotic barriers

Factors that prevent hybrid offspring from developing into fertile adults.

Allopatric Speciation

The formation of new species due to geographic isolation.

Sympatric Speciation

The formation of new species without geographic isolation, usually due to chromosomal changes.

Morphospecies Concept

A definition of species based on physical traits.

Biological Species Concept

Species defined by their ability to interbreed and produce viable, fertile offspring.

Phylogenetic Species Concept

Species defined by their ancestry and evolutionary history.

X linked disease

A genetic disorder associated with mutations on the X chromosome, often affecting males more severely due to their single X chromosome.

Most common in males

sex influenced inheritance

A type of inheritance where the expression of a trait is influenced by the sex of the individual, often resulting in different phenotypes in males and females.

Sex linked inheritance

A pattern of inheritance where genes located on the sex chromosomes (X or Y) determine traits, often leading to different expressions in males and females.

population

A group of individuals of the same species that live in a specific area and interbreed, sharing a common gene pool.

gene pool

The total collection of genes and their alleles in a population, representing the genetic diversity available for reproduction.

Microevolution

The process of small-scale evolutionary changes within a population, often involving shifts in allele frequencies over time due to factors like mutation, selection, gene flow, and genetic drift.

macroevolution

Genetic changes that give rise to a new species

What is the difference between a microevolution and macroevolution?

Microevolution refers to small-scale changes within a population, while macroevolution encompasses large-scale changes that can lead to the formation of new species.

Hardy weinberg equation

is a mathematical formula used to calculate the expected frequencies of genotypes in a population that is not evolving, based on the assumption of random mating and no evolutionary influences. P² +2pq +q³=1 and p+q=1

Genetic evolution

refers to the process through which populations change over time due to genetic variations, leading to adaptations and potentially new species.

Directional selection

is a mode of natural selection where one extreme phenotype is favored over others, causing a shift in the population's phenotype distribution.

Stabilizing selection

is a mode of natural selection that favors intermediate variants and acts against extreme phenotypes, thereby reducing variation in a population.

Disruptive selection

is a mode of natural selection that favors extreme phenotypes at both ends of the spectrum, potentially leading to two or more contrasting phenotypes in a population.

speciation

Formation of a new species. This process occurs when populations of a species become reproductively isolated and evolve independently.

Subspecies

Distinct population within a species that has unique traits or characteristics, often due to geographic or ecological differences.