Bio 107 Exam 1

microevolution

Small changes in gene/allele frequencies occur within a single population over a short time

macroevolution

Processes that give rise to new species/taxonomic groups with divergent characteristics

traits

distinguishing qualities or characteristics

gene

regions of DNA that contain information used to make proteins

Allele

Alternative form of a single gene code for different versions of the same trait

natural selection

organisms with helpful traits survive and reproduce (survival of the fittest)

population

all organisms of the same species in an area

population genetics

study of the distribution and frequency of alleles in a population

hardy-weinburg principle

gene (allele) frequencies will not change from one generation to the next if certain assumption hold true, no population is immune to evolution, principle gives mathematical baseline of non-evolving population for comparison

genetic mutations

introduces new alleles (mutations must be present in the germline for them to be inherited by the next generation)

gene flow

movement of alleles between populations by migration of breeding individuals

genetic drift

random change to distribution of alleles with no advantage to the population, the effect is inversely proportional to population size, due to random chance or bottleneck effect and founder affect

bottleneck effect

population experiences drastic reduction in numbers

founder effect

group of individuals is isolated

non-random mating

an organism makes a more deliberate choice in who they mate with, falls into assertive and disassortive mating

assortative mating

a type of non-random mating where individuals with similar phenotypes mate more frequently than expected by chance.

disassortative mating

a type of non-random mating where individuals with different phenotypes mate more frequently than expected by chance.

selection

(selection) alleles that make an organism more fit are more likely to be passed on

adaptive evolution

natural selection increases frequency of beneficial alleles in a population

stabilizing selection

a type of natural selection that favors intermediate phenotypes, reducing extremes.

directional selection

a type of natural selection that favors one extreme phenotype over others, leading to a shift in the population's traits.

diversifying selection

a type of natural selection that favors extreme phenotypes at both ends of the spectrum, often leading to increased genetic variation in a population.

speciation

formation of two species from one original species

species

a group of organisms that can successfully interbreed and produce fertile, viable offspring

allopatric speciation

speciation due to geographical separation and subsequent evolution

sympatric speciation

speciation occurring within a parent species in the same location

prezygotic barrier

a reproductive barrier that occurs before fertilization, preventing mating or fertilization between different species.

postzygotic barrier

a reproductive barrier that occurs after fertilization, affecting the viability or fertility of the offspring.

temporal isolation

a prezygotic barrier where species breed at different times, preventing mating.

behavioral isolation

a type of prezygotic barrier in which two species have different mating behaviors or rituals, preventing them from interbreeding.

5 main causes of evolution

the five main causes of evolution are natural selection, mutation, gene flow, genetic drift, and non-random mating.

hardy-weinburg 5 assumptions

These are the conditions that must be met for a population to remain in genetic equilibrium: no mutations, random mating, no natural selection, extremely large population size, and no gene flow.

4 examples of reproductive isolation

Reproductive isolation refers to mechanisms that prevent different species from interbreeding and producing viable offspring. pre zygotic barrier, post zygotic barrier, temporal isolation, behavioral isolation

steps in allopatric speciation

geographic isolation, genetic drift, and the development of reproductive barriers.

variations

in genetic traits among individuals within a population, which can lead to differences in phenotype and play a key role in evolution.

mechanisms of speciation

Processes that drive the formation of new species, including allopatric and sympatric speciation.

phylogeny

evolutionary history and relationship of an organism or group of organisms

phylogenetic tree

diagram used to reflect phylogeny relationships

branch point

A point on a phylogenetic tree where a lineage diverges into two or more descendant lineages, representing a common ancestor.

basal taxon

a lineage that diverges early in the history of a group, often serving as a reference point for comparison with other taxa.

sister taxa

groups of organisms that share an immediate common ancestor and are each other's closest relatives.

polytomy

A branch point on a phylogenetic tree that represents an unresolved pattern of divergence, indicating that three or more lineages have diverged simultaneously.

Claudes/monophyletic groups

are hypothetical situations in which traits are analyzed to determine evolutionary relationships among species.

limitations of phylogenetic trees

groups that are closely related may not look similar and branches do not typically account for length of time

taxonomy

science of classifying organisms to build internationally accepted hierarchical classification systems where each organism is placed into increasingly more inclusive groups

taxonomy groups

domain, kingdom, phylum, class, order, family, genus, species, and sometimes subspecies.

taxon

name at each level (taxonomic)

binomial nomenclature

system of naming organisms using two names, the genus and species.

6 kingdoms in biology

plantae, fungi, protists, animals, eubacteria, archaebacteria

3 domains

bacteria, archaea, eukarya.