Fund of Evol Exam 2

ortholog

homologous genes seperated by a speciation event

gene recruitment

the co-option of a particular gene or network for a totally different function as a result of a mutation

transcription factor

a protien that binds to a sequence of DNA and turns it on or off like a switch

gene control regions

upstream sections of DNA that include the promoter region as well as other regulatory sequences that influence the transcription of DNA.

anisogamy

fushion of two disimilar gametes (egg and sperm)

male biased operational sex ratio

more males and females prepared to mate

antagonistic coevolution

ducks (females can control male sperm not intragender)

How have bdelloid rotifers been able to avoid the disadvantages of parthenogenetic reproduction?

horizontal gene tranfer and incorporating forbien DNA fragments

Muller’s ratchet

mutations accumulate irreversibly in the asexual populations, causing their populations to die out quickly.

quantitative genetics

the study of continuos phenotypic traits and their underlying evolutionary mechanisms

phenotypic variance

stattical distrinution of traits on a radient in a population. made up of

Environemntal variance

phenotypic variance

genetic variance

phenotypic variation bell curve

polygenic basis for the trait

phenotypic variance equation

Vp = Ve + Vg

heretibility (H²)

the protoprtion of the totatl phenotypic variation of a trait thar is attributed to genetic varience

H²

Vg/Vp

Vg

Va = addititve variance

Vd = varience due to dominace effects on alleles

Vi = varience due to epistatic interaction effects on alleles

What component of genetic variance is used in narrow heritiblity

Va (addtitve varience)

h² (narrow heritibilty)

Va / Vp

A trait can be acted on only if it is

1. Heritable

2. Has a strong selection differential

stabilizing selection

selects for mean trait

directional selection

select trait in one extreme

disruptive selection

selects for traits on both extremes

selection differential (S)

S = the difference in means of reproducing population and total population

S = mean(repro) - mean(pop)

R = h² x S (heritibility equation)

h²= 0 = no response

h²= 0<h²<1 = response of h² x S

h² = 1 = respose of selection differential

linkage equilibrium

an allele at one locus is independent of any other allele at a second locus

ex. different chromosomes or far apart on the same chromosome

what could cause linkage equilibrium

genetic drift

linkage dsequilibrium

a statistical state where an allele at one locus is non randomly associated with the prescence or absence of another allele at a different location

has different degree depending on distance

True or False: linkage disquilibrium needs a physical linkage?

False

what does linkage disquilibrium indicate

there is a new allele (all new alleles are in this state) and can tell us if a gene was under positice selection

selective sweep

under strong positive selection an allele can reach fixation extremely fast, causing it to remain in linkage disequilibrium

super genes

sets of alleles that increase fitness so much when present ALL TOGETHER that they resist equilibrium

norm of reaction

the variety of different phenotypic states that can be produced by a single genotype under different environmental conditions

what is norm of reaction used for

to estimate the phenotypic presentation of a species under certain environmental conditions and vice versa

does selection effect phenotypic plasticity?

yes! when Vgxe (genetic interaction with the environment) > 0

when is plasticity good?

when environement is frequent and predictable

study: finches with various peak sizes. after drought little birds were NOT fit. in times of heavy rain they got a BOOST in fitness

concept: selection varies over time

study: coat color in field mice. dark mice in 2 different areas but one had Agouti gene mutations and the others were dark by a different mechanism

concept: multiple evolutionary pathways exsist to solve the same problem

study: gall size in flies are usually medium because if too small the wasps eat the babies but if too big the birds eat the babies

concept: humns drive evolutionary change

study: Intentional - coevolution in dogs

Unintentional - antibiotic resistance

concept: organisms respond to multiple selection pressures at once

antagonistic pleitropy

a gene is beneficial in early life or under some condition but is detrimental later on

molecular characters

nucleotides, amino acids, proteins, alleles

molecular character states

A, T, G, C

homoplasy is more common in which type of data?

molecular

coalescence

the process in which the geneology of any pair of homologous alleles merges in a common ancestor

incomplete lineage sorting

when gene trees do not match species trees

introgression

the transfer of genetic material from one species to the gene pool of a different species (similar to horizontal gene transfer).

ex. human hace Neanderthal DNA despite not being hybrids

how to combat incomplete lineage sortage?

include more loci

methods for picking most likely tree from genetic data

• Maximum parsimony (no model)

• Maximum likleihood (model)

• Bayesian method (model)

neutral theory of molecular evolution

neutral mechanisms become fixed in lineages at a regular rate

synonymous (silent) mutations

so not alter amino acid sequence if the protein CANNOT be selected for

nonsynonymous

alters the amino acid sequences of the protein and CAN be selected for

dN

rate of nonsynonymous subsititutions

dS

rate of synonymous substitutions

dN = dS (dN/dS = 1)

accept the neutral theory (null hypothesis)

dN > dS (dN/dS > 1)

positive selection

dN < dS (dN/dS < 1)

purifying selection

maximum likelihood

statistical method that involves adjusting branch lengths to what is most likely in a particular data set

bayesian method

applies prior knowledge to Bate’s original probalility model

genetic hitchhiking

strongly selected alleles are frequently found in a poopulation surrounded by the same set of alleles at neighboring locations

gene control region

an upstream section of DNA that includes a promotor region (to influence transcription)

repressor

a protein that binds to a sequence of DNA or RNA and inhibits expression

transcription factor

a protein that binds to specific DNA sequences and acts like light switch

promiscuois protiens

carry more than one function

gene recruitment

The co-option of a particular gene or network for a totally different function as the result of a mutation

gene duplication

gene dupolicates and that duplication can be tinkered with without harming organism

• results in paralogs

paralogs

a homologous gene that arises by gene duplication

regulatory networks

Systems of interacting genes, transcription factors, promotors, RNA and other molecules that function like biological circuits. A few of these start a cascade of increasing development.

developmental control genes

control the expression of other genes

development

the genotype/phenotype map in multicelluar organisms

cells → communication between cells → cells send and reciveve positional info → info used to change cell fate/function

Hox genes

developmental genes that specify the anterior-postierior location of body segments in animals

encode proteins that regulate transcription

complex adaptations

Phenotypes are considered complex when they are influenced by many environmental and genetic factors, and when multiple components must be expressed together for the trait to function.

ex. eye

can proteins adopt new functions?

Yes! By changing time, place, and amount of protein production

deep homology

when developoment and growth of specific traits in diferent lineages develops due to underlying mechanisms from a common ancestor

contraints on evolution

1. laws of physics

2. antagonistic pleitropy

3. evolutionary history

disadvantages of sex

disease, cost of finding a mate, reduced relatedness

advantages of sex

genetic novelty, clearance of deleterious mutations, enhanced adaptation, faster evolution (v.s. parasites)

isogamy

gametes are identical

anisogamy

mutliple types of gametes: one is large and immobile, one is small and mobile

key facotor in sexual strategies

parental investment

Biased operational sex ratio

The ratio of sexually receptive males to females at one time

Male biased operational sex ratio

More males than females, most females will mate but very few males will

Female biased operational sex ratio

More females than males

intersexual selection

competition between individuals of the same sex compete against EACH OTHER for access to the other sex

intrasexual selection

competition between sexs in which one sex chooses mates from the other

monogomous breeding systems

mutual choice, slower evolutionary changes, limited or no sexual dimorphism

darwinian demon (chad of the animal)

Maximize all aspects of fitness simultaneously with no contraints

• begins reproducing immediatley

• produce infinite offspring

• live forever

darwinian dolt (cuck of the animal)

Risk at every turn

• delayed maturation

• only reproduce one offsprinf

• reproduces asexually

natural selection wants

to maximize offspring making it to maturity

senescence

age related decline of physical function and living ability. caused by prioritization of survivorship and reproduction in earlier life

trade-offs

Investment in early reproduction often reduces reproduction late in life

mammal parental care

90% female

fish parental care

70% male

bird parental care

90% biparental

amphibian parental care

50-50 male only female only

Trivers-Willard Hypothesis

females produce female offspring when resources are low and male when resources are abundant