POB2 Midterm 2

natural selection

The processes that change allele frequencies when certain heritable traits are associated with different levels of reproductive success.

evolution

A change in allele frequencies

directional selection

Natural selection that favors an extreme phenotype

Stabilizing selection

Natural selection that favors the average phenotype in the population and acts against extreme phenotypes

Adaptation

A heritable trait that increases fitness in a particular environment

fitness

The ability to produce viable offspring

Artificial selection

When humans actively and consciously select which individuals will be the parents of the next generation

Genetic drift

Any change that occurs in allele frequencies that is due to chance

Founder events

One of the several types of events that can cause genetic drift; occurs when a relatively small number of individuals disperse to a new habitat and found a completely new population.

Genetic bottlenecks

One of the several types of events that can cause genetic drift. They occur when a species undergoes a large and rapid decrease in population size due to a disease epidemic, catastrophic storm, or other change.

Gene flow

An evolutionary process that changes allele frequencies through the movement of individuals and their alleles from one population to another. Homogenizes alleles frequencies among populations.

Maladaptive

Leading to lower fitness

Mutation

Any change in the sequence of DNA, and thus a change in genetic information. Introduces new alleles into population

Deleterious mutation

A mutation or other event that lowers fitness.

Speciation

The process of genetic isolation and genetic divergence that is responsible for the creation of new species

Species

An evolutionarily independent unit in nature— meaning, a population or group of populations that is genetically isolated from others and is thus changing under the effects of evolution independently of others.

Population

A group of individuals from the same geographic region that regularly mate together

Morphological species concept

Identifying species based on anatomical differences

Biological species concept

Identifying species based on evidence of reproductive isolation

Phylogenetic species concept

Identifying species as the smallest monophyletic groups on the tree of life.

Null model

A model that predicts the data you should expect to see if a process is not working—meaning, when a particular causative agent is not impacting the situation.

Hardy-Weinberg Principle

A null model stating that if no selection, drift, gene flow, or mutation occur, and if mating is random with respect to the gene in question, then allele frequencies will not change from one generation to the next and genotype frequencies will be in the proportions p², 2pq, and q², where p and q are the frequencies of two alleles at that gene.

Assortative mating

Mate choice based on similarities or dissimilarities in phenotype.

Inbreeding

Mating among relatives

Gene Pool

A concept used in predicting the results from random matings among all of the individuals in a population, by supposing that all gametes are tossed into pool and then drawn out at random to produce offspring.

Phylogenetic tree

A graphical depiction of evolutionary history, or phylogeny.

Homologous traits

Any characteristic, ranging from a single nucleotide in DNA to body parts, that is observed in multiple species and inherited from the same common ancestor

Taxon

A named group of organisms

Monophyletic group

An ancestor and all of its descendants

Synapomorphy

A trait that one group has that no one else does; define monophyletic groups.

Homoplasy

Similarity in traits that is not due to common ancestry but due to independent evolution

Outgroup

Any lineage that is not part of the monophyletic group that is the focus of a phylogenetic tree.

Parsimony

A criterion in logic that states that the simplest explanation is the most likely to be correct,

Fossil record

Any trace of an organism that lived in the past

Extinction

The demise of a species, meaning that no individuals of that species are still alive

Mass extinction

An event where at lest 60% of the species currently alive disappear in less than one million years.

Niche

The range of resources and environments that a species uses.

Relative dating

Assigning younger-to-older ages to rocks based on their positioning relative to each other

Absolute dating

Assigning chronological ages to rocks using data on the decay rate of a specific radioactive isotope and the relative amounts of that isotope and the element produced when it decays.

evolutionary developmental biology (evo-devo)

A research field focused on understanding the genetic and molecular mechanisms responsible fore for evolutionary change— especially the origin of novel traits.

Background extinction rate

The normal, long-term average at which species go extinct over time, outside of mass extinction events.

plasmid

A small, extrachromosomal loop of DNA. Many of the best-studied plasmids carry genes for antibiotic resistance.

Peptidoglycan

A structural carbohydrate found in bacterial cell wall. It is a lattice made of sugars linked with (beta)-(1,4)-glycosidic bonds that have short chains of peptide-bonded amino acids protruding from them.

Prokaryote

Bacteria and archaea—organisms whose cells lack a nucleus

Microbe

Viruses and any microscopic organism, including bacterial, archaean, and eukaryotic species.

Primary producer

An organism that produces its own food, usually via photosynthesis. Primary producers are the source of the chemical energy and carbon compounds that all other organisms rely on for food.

Microbiome

The collection of microbes that lives in a particular location.