IB 150 Exam 3 study set

artificial selection

deliberate manipulation by humans, as in animal and plant breeding, of the genetic composition of a population by allowing only individuals with desirable traits reproduce

natural selection

the process by which individuals with certain heritable traits tend to produce more surviving offspring than do individuals without those traits, often leading to a change in makeup of the population

1) heritable variation leads to 2) differential reproductive success

evolution by natural selection occurs when...

fitness

the ability of an individual to produce viable offspring relative to others of the same species

adaptation

any heritable trait that increases the fitness of an individual with that trait, compared with individuals without that trait, in a particular environment

natural selection, genetic drift, gene flow, mutation

what are the four processes that change allele frequencies?

hardy-weinberg principle

a principle of population genetics stating that genotype frequencies in a large population do not change from generation to generation in the absence of evolutionary processes (e.g. mutation, gene flow, selection) and non random mating

gene pool

all of the alleles of all the genes in a certain population

1) random mating 2) no natural selection 3) no genetic drift (random allele frequency changes) 4) no gene flow 5) no mutation

what are the five assumptions of the hardy weinberg principle?

inbreeding

mating between closely related individuals; increases homozygosity of a population and often leads to a decline in the average fitness via selection (inbreeding depression)

inbreeding depression

in inbred offspring, fitness declines due to deleterious recessive alleles that are homozygous, thus exposed to selection

no, b/c non random mating only changes genotype frequencies, not allele frequencies

is non random mating an evolutionary process?

deleterious

in genetics, referring to any mutation, allele, or trait that reduces an individual's fitness

sexual selection

a type of natural selection that favors individuals with traits that increase their ability to obtain mates; acts more strongly on males than females

genetic variation

the number and relative frequency of alleles present in a particular population; also the proportion of phenotypic variation in a trait that is due to genetic rather than environmental influences in a certain population in a certain environment

directional selection

a mode of natural selection that favors one extreme phenotype with the result that the average phenotype of a population changes in one direction; usually reduces genetic variation in a population

purifying selection

selection that lowers the frequency of or even eliminates deleterious alleles

stabilizing selection

a mode of natural selection that favors phenotypes near the middle of the range of phenotypic variation; reduces overall genetic variation in a population

disruptive selection

a mode of natural selection that favors extreme phenotypes at both ends of the range of phenotypic variation; maintains overall genetic variation in a population

balancing selection

a mode of natural selection in which no single allele is favored in all populations of a species at all times; instead there is a balance among alleles in terms of frequency and fitness

heterozygote advantage

a pattern of natural selection that favors heterozygous individuals compared with homozygotes; maintains genetic variation in a population, thus is a form of balancing selection

frequency dependent selection

a pattern of selection in which certain alleles are favored only when they are rare; a form of balancing selection

INTERsexual selection

the sexual selection of an individual of one gender for mating by an individual of the other gender (usually by female choice)

INTRAsexual selection

competition among members of one gender for an opportunity to mate (usually male-male competition)

sexual dimorphism

any trait that differs between males and females

ecological/environmental selection

a type of natural selection that favors individuals with heritable traits that enhance their ability to survive and reproduce in a certain physical and/or biological environment, excluding their ability to obtain a mate

genetic drift

any change in allele frequencies due to random events; causes allele frequencies to drift up and down randomly over time, and eventually can lead to the fixation or loss of alleles

sampling error

the selection of a non-representative sample from some larger population, due to chance

founder effect

a change in allele frequencies that often occurs when a new population is established from a small group of individuals due to sampling error

genetic bottleneck

a reduction allele diversity resulting from a sudden reduction in the size of a large population due to a random event

gene flow

the movement of alleles between populations; occurs when individuals leave one population, join another, and breed

mutation

where do entirely new alleles come from?

point mutation

a mutation affecting only one or very few nucleotides in a gene sequence

lateral gene transfer

the transmission of genes from the parental generation to offspring via sexual or asexual reproduction

beneficial allele

an allele that allows individuals to produce more offspring

fossil record

all of the fossils that have been found anywhere on Earth and that have been formally described in the scientific literature

population thinking

the ability to analyze trait frequencies, event probabilities, and other attributes of populations of molecules, cells or organisms

extant species

a species that is living today

transitional feature

a trait that is intermediate between a condition observed in ancestral (older) species and the condition observed in derived (younger) species

vestigial trait

a reduced or incompletely developed structure that has no function or reduced function, but is clearly similar to functioning organs or structures in closely related species

phylogenetic tree

a branching diagram that depicts the evolutionary relationships among species or other taxa

homology

similarity among organisms of different species due to their inheritance from a common ancestor: DNA sequences, proteins, body parts

genetic homology

similarity in DNA nucleotide sequences, RNA nucleotide sequences, or amino acid sequences due to inheritance from a common ancestor

developmental homology

a similarity in embryonic form, or in the fate of embryonic tissues, that is due to inheritance from a common ancestor

structural homology

similarities in adult organismal structures that are due to inheritance from a common ancestor

morphology

the shape and appearance of an organism's body and its component parts

if mutation, selection, and genetic drift cause isolated populations to diverge sufficiently; genetic isolation and genetic divergence

what causes speciation to occur?

lack of gene flow

what causes genetic isolation?

selection, genetic drift, and mutation in isolated populations

what causes genetic divergence?

speciation

the evolution of two or more distinct species from a single ancestral species

species

an evolutionarily independent population or group of populations; generally distinct from other species in appearance, behavior, habitat, ecology, genetic characteristics, etc.

the biological species concept

the definition of a species as a population or group of populations that are reproductively isolated from other groups. Members of a species have the potential to interbreed in nature to produce viable, fertile offspring but cannot interbreed successfully with members of other species

1) the biological species concept 2) the morphospecies concept 3) the phylogenetic species concept

what are the three criteria used to identify a species?

pre-zygotic isolation

reproductive isolation resulting from any one of several mechanisms that prevent individuals of two different species from mating

post-zygotic isolation

reproductive isolation resulting from mechanisms that operate after mating of individuals of two different species occurs; the most common mechanisms are the death of hybrid embryos or reduced fitness of hybrids

morphospecies concept

the definition of a species as a population or group of populations that have measurably different anatomical features from other groups

polymorphic species

a species that has two or more distinct phenotypes in the same interbreeding population at the same time

cryptic species

a species that cannot be distinguished from similar species by easily identifiable morphological traits

phylogenetic species concept

the definition of a species as the smallest monophyletic group in a phylogenetic tree

monophyletic species/clade/lineage

an evolutionary unit that includes an ancestral population and all of its descendants but no others

synapomorphy

a shared, derived trait found in two or more taxa that is present in their most recent common ancestor but is missing in more distant ancestors; useful for inferring evolutionary relationships

subspecies

a population that has distinctive traits and some genetic differences relative to other populations of the same species but that is not distinct enough to be classified as a separate species

allopatry

condition in which two or more populations live in different geographic areas

allopatric speciation

speciation that occurs when populations of the same species become geographically isolated, often due to dispersal or vicariance

vicariance

the physical splitting of a population into smaller, isolated populations by a geographic barrier

sympatry

condition in which two or more populations live in the same geographic area, or close enough to permit interbreeding

sympatric speciation

the divergence of populations living within the same geographic area into different species as the result of their genetic (not physical) isolation

sister species

closely related species that occupy adjacent branches in a phylogenetic tree

polyploidy

the state of having more than two full sets of chromosomes, either from the same species (autopolyploidy) or from different species (allopolyploidy)

autopolyploid

the state of having more than two full sets of chromosomes due to a mutation that doubled the chromosome number; all the chromosomes come from the same species

allopolyploid

the state of having more than two full sets of chromosomes due to hybridization between different species

reinforcement

the natural selection for traits that prevent interbreeding between recently diverged species

hybrid zone

a geographic area in where interbreeding occurs between two species, sometimes producing fertile hybrid offspring

phylogeny

the evolutionary history of a group of organisms

tree of life

the most universal of all phylogenetic trees, depicting the evolutionary relationships among all living organisms on earth

tip

the end of the branch on a phylogenetic tree that represents a specific species or larger taxon that has not yet produced descendants-- either a group living today or a group that ended in extinction

outgroup

a taxon that is closely related to a particular monophyletic group but is not part of it

ancestral trait

a trait found in the ancestors of a particular group

derived trait

a trait that is clearly homologous with a trait found in an ancestor of a particular group, but that has a new form

parsimony

the logical principle that the most likely explanation of a phenomenon is the most economical or simplest; in relation to phylogenetic trees, it suggests that the one requiring the fewest evolutionary changes is most likely to be correct

homoplasy

similarity among organisms of different species due to reasons other than common ancestry, such as convergent evolution (ex: wings of birds and bats)

convergent evolution

the independent evolution of similar traits in distantly related organisms due to adaptation to similar environments and a similar way of life

evo devo

evolutionary developmental biology, focuses on how changes in developmentally important genes have led to the evolution of new phenotypes

adaptive radiation

rapid evolutionary diversification within one lineage, producing many descendant species with a wide range of adaptive forms

fauna

all the animal species characteristic of a particular region, period, or environment

basal metabolic rate

the total energy consumption by an organism at rest in a comfortable environment

ficks law of diffusion

a mathematical relationship that describes the rates of diffusion of gases