bio pt2 mt 2

Natural selection

The process whereby organisms better adapted to their environment tend to survive and produce more offspring.

Catastrophism

The theory that the Earth's geology and life forms are primarily shaped by sudden, short-lived events.

Gradualism

The theory that changes in the Earth's geology and life forms occur slowly over long periods.

Descent with modification

The process where descendants differ from their ancestors over time, leading to evolution.

Homologous traits

Similar traits in different organisms inherited from a common ancestor.

Analogous traits

Traits that are similar due to convergent evolution, not because of shared ancestry.

Vestigial structure

A structure that has lost much or all of its original function through the course of evolution.

Evolution

The change in the genetic composition of a population over generations.

Variation

Differences in traits among individuals in a population.

Inheritance

The process by which genetic information is passed from parents to offspring.

Differential success

The concept that some individuals in a population reproduce more successfully than others, affecting evolution.

Stabilizing selection

Natural selection that favors average phenotypes and reduces variation.

Directional selection

Natural selection that favors one extreme phenotype over others, shifting the mean.

Disruptive selection

Natural selection that favors extreme phenotypes at both ends, increasing variation.

Frequency-dependent selection

Selection that favors traits based on their rarity in the population.

Sexual selection

Natural selection arising through preference by one sex for certain characteristics in individuals of the other sex.

Intrasexual selection

Competition between individuals of the same sex for mates.

Intersexual selection

Mate choice where one sex is selective in choosing a partner.

Kin selection

Natural selection that favors altruistic behavior towards relatives.

Inclusive fitness

An individual's total reproductive success, including their contributions to the survival and reproduction of relatives.

Hamilton’s rule

A principle that describes the conditions under which altruistic behavior is favored by natural selection.

Gene

A segment of DNA that codes for a specific trait or function.

Gene expression

The process by which information from a gene is used to synthesize functional gene products like proteins.

Central dogma

The framework for understanding the flow of genetic information: DNA is transcribed to RNA, which is then translated into proteins.

Transcription

The process of copying a segment of DNA into RNA.

Translation

The process by which RNA is decoded to produce proteins.

Allele

A variant form of a gene that can produce different traits.

Genotype

The genetic constitution of an individual organism.

Phenotype

The observable physical or biochemical characteristics of an organism, determined by both genetic makeup and environmental influences.

Homozygous

Having two identical alleles for a particular gene.

Heterozygous

Having two different alleles for a particular gene.

Law of segregation

Mendel's law stating that the two alleles for a trait segregate during gamete formation.

Law of independent assortment

Mendel's law stating that alleles of different genes assort independently of one another.

Meiosis

A type of cell division that results in four daughter cells, each with half the number of chromosomes of the parent cell.

Complete dominance

A form of inheritance where one allele completely masks the other in the phenotype.

Incomplete dominance

A form of inheritance where the heterozygote has a phenotype that is intermediate between the two homozygotes.

Codominance

A form of inheritance where both alleles in a heterozygote are fully expressed.

Pedigree

A diagram that shows the occurrence of a genetic trait in several generations of a family.

Pleiotropy

When one gene influences multiple phenotypic traits.

Polygenic inheritance

Inheritance of a trait that is controlled by multiple genes.

Quantitative traits

Traits that show a continuous range of phenotypes and are influenced by multiple genes and environmental factors.

Epistasis

An interaction between genes whereby one gene masks or interferes with the expression of another.

Hardy-Weinberg equilibrium

A principle stating that allele and genotype frequencies in a population remain constant from generation to generation in the absence of evolutionary influences.

Genetic drift

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

Founder effect

Genetic drift that occurs when a small group of individuals establishes a new population.

Genetic bottlenecks

A dramatic reduction in population size that results in a loss of genetic diversity.

Non-random mating

Mating that occurs based on specific traits rather than random chance.

Competitive exclusion principle

Two species competing for the same limited resource cannot coexist.

Resource partitioning

The division of limited resources by species to help avoid competition.

Character displacement

The tendency for species to evolve non-overlapping traits to minimize competition.

Symbiosis

A close and often long-term interaction between two different biological species.

Fundamental niche

The potential mode of existence of a species, given its adaptations.

Realized niche

The actual mode of existence of a species, which results from its adaptations and interactions with other species.

Batesian mimicry

A form of mimicry where a harmless species resembles a harmful one to avoid predation.

Müllerian mimicry

An evolutionary phenomenon whereby two or more harmful species evolve to look similar.

Microevolution

Small-scale evolutionary changes within a species.

Macroevolution

Large-scale evolutionary changes that result in the formation of new species.

Phylogenetic tree

A branching diagram showing the evolutionary relationships among various biological species.

Extinction

The end of an organism or a group of organisms, commonly referred to as a species.

Rapid speciation

The emergence of many new species in a relatively short geological time frame.

Adaptive radiation

The rapid diversification of a single lineage into a variety of forms, filling different ecological niches.

Polyploidy

The condition of having more than two complete sets of chromosomes.

Allopolyploidy

Polyploidy resulting from the hybridization of two different species.

Autopolyploidy

Polyploidy resulting from the self-duplication of chromosomes of a single species.

Sympatric populations

Populations of different species that live in the same geographic area.

Allopatric populations

Populations of different species that are geographically isolated from one another.

Postzygotic barrier

A reproductive barrier that occurs after fertilization, preventing hybrid offspring from developing into viable, fertile adults.

Types of postzygotic barriers

Includes hybrid inviability, hybrid sterility, and hybrid breakdown which affect the fitness and reproductive capability of hybrids.

Prezygotic barrier

A reproductive barrier that prevents fertilization from occurring, including temporal, habitat, behavioral, mechanical, and gametic isolation.

Temporal isolation

A type of prezygotic barrier where species reproduce at different times of the day or year.

Habitat isolation

A type of prezygotic barrier where species live in different environments, preventing them from mating.

Behavioral isolation

A prezygotic barrier arising from differences in courtship behaviors or mating rituals.

Mechanical isolation

A type of prezygotic barrier where differences in reproductive structures prevent successful mating.

Gametic isolation

A prezygotic barrier where mating occurs, but sperm and egg are incompatible.

Biological species concept

Defines species as groups of interbreeding natural populations that are reproductively isolated from other such groups.

Pros of biological species concept

Emphasizes reproductive isolation, helps understand speciation processes.

Cons of biological species concept

Cannot be applied to asexual organisms or extinct species; does not account for genetic exchange through hybridization.

Lineage species concept

Defines species as branches on the tree of life, focusing on the evolutionary history of populations.

Pros of lineage species concept

Considers both asexual and sexual organisms, better for understanding evolutionary relationships.

Cons of lineage species concept

Relies on phylogenetic data which may be incomplete or uncertain, can complicate the definition of species.

Morphological species concept

Defines species based on physical characteristics and observable traits.

Pros of morphological species concept

Simple to apply, does not require knowledge of reproductive capabilities, useful for fossil identification.

Cons of morphological species concept

Can be subjective, may overlook cryptic species that appear similar but are genetically different.

Reduced hybrid viability

F1 hybrid offspring do not complete development or have low survivorship

Reduced hybrid fertility:

F1 hybrid offspring are viable, but have reduced fertility/fecundity

Hybrid breakdown

F1 hybrid offspring are viable and fertile, but offspring of these hybrids (F2) are inviable or sterile