evolution midterm

what is a proximate cause

how biological phenomena occur

What is a pre adaptation that’s filling a new function

Exadaptation

what is an ultimate cause

why biological phenomena occur

what is the definition of evolution

inherited changes in properties of populations over the course of generations

what is a theory

hypothesis with enough evidence

what is evidence

results from testing theories

what is a fact

simple confirmable observations

what are the 2 major parts of the origin of species

common descent and descent with modification

what are some aspects of darwins theory

adaptations are passed down through heritable traits within populations, species developed from a common ancestor

what are some aspects of lamarcks theory

adaptations are gained over the lifetime of an individual, species just appeard fully formed

what are the facets of microevolution

natural selection, genetic drift, mutation and gene flow

what is macroevolution

enough microevolution acts that create speciation

what aspect of evolution is shown by a phylogenetic tree

speciation and common descent

what is LUCA

last universal common ancestor

what does monophyletic refer to

when all members of a clade share a common ancestor

what is anagenesis

evolution of traits within a lineage

what is cladogenesis

change of traits that makes 1 lineage into multiple

what are sister groups

two clades that diverged from eachtother

what causes the branch of a phylogenetic tree to rejoin

horizontal gene transfer and hybridization

what does homologous mean

same characteristics inherited from a common ancestor

how can you assume how old characteristics are in a lineage

see how long the branches are on some trees, they can represent how many base pairs have been substituted

what is homoplasy

development of similar traits in multiple lineages (convergent evolution)

what is mosaic evolution

evolution that happens at different rates, due to differing pressure for traits. So different traits can evolve at different rates within a lineage

what is an adaptation

a trait that improves survival and fitness

what is natural selection

selection for a trait that increases fitness within a population

what two things are required for natural selection to occur

a trait must be adaptive and the variation within the trait must be heritable

what traits are used in the “selection for”

traits that increase fitness

what traits are used in the “selection of”

traits that can be located on a nearby locus to the desired trait on the chromosome that can be accidentally selected for when undergoing natural selection

How can we decide if a trait is adpative

complexity: complex traits dont evolve by accident

structure/function: engineering

experiments: can be used to identify traits linked to survival

2 contraints on rapid adaptation and selection

not enough genetic variability and phylogenetic restraints limits on structures

why is adaptation selfish

natural selection can only impact phenotypes it can see are positively aiding the organisms fitness. so cannot adapt for other reasons.

what role does DNA play in inheritance and codons

genome encodes for proteins using codons. Genes are made of three sets of bases which make up a codon.

what is coding DNA

exons, DNA strands used to code genome

what is non coding DNA

introns, cut out and allows for alternate splicing

phenotypes

expressed portion of trait, physical portion

genotype

gene sequence that encode for different phenotypes

segregation

during meiosis only one allele from the parent is included in the gamete

recombination

pair of homologous chromosomes crossing over and swapping genetic material, closer genes to the loci the higher the recombination rate

Harvey Weinburg equillibrium

expected gene frequency from one generation to the next in ideallic population.

what are assumptions made in HWE

infinaite population size, no mutations, no natural selection, no migration and completely random mating. Used as a null model to compare values to.

linkage disequilibrium (D)

non random association between alleles at two loci, will lower genetic variability

linkage equillibrium

if recombination is equally likley between two loci

point mutations

single nucleotide change, in first two postions usually non synonomous and in third usually synonomous

structural mutation

changes in more than one base

whole genome duplication

two diploid gametes fuse together and create offspring with 4 copies of chromosomes

mutation types

deleterious and beneficial

what are mutations important to organism evolution

increases genetic diversity and can help with pre adaptations

pleiotropy

mutation that affects multiple traits, almost always when a mutation impacts phenotype expression

germ line mutations

mutations inherited through gametes

somatic mutations

not inherited but still decrease fitness

what are three types of non genetic inheritance

epigenetics, maternal effects and cultural inheritance

what is absolute fitness (W)

number of offspring an individual will have over their lifetime

relative fitness (w)

compare fitness value among individual by dividing W by a reference

what is selection coefficient (s)

proportional to strength of selection and genetic diversity in a population.

what is genetic correlation

when genes are linked and inherited together when phenotype is selected for

overdominance

Heterozygosity is selected for which aids in maintaining genetic variation

negative frequency dependance

relative fitness is dependant on frequency

underdominance

Heterozygosity decreases fitness which acts to decrease genetic variation

positive frequency dependant selection

selection favoured is whichever is more common in population which also decreases genetic variability

mutation selection balance

natural selection acts to remove deleterious mutations from populations = purifying selection

genetic drift

loss of genetic variation within a population, most common in small popn

how would selection or drift over power eachother

drift is stronger than selection in small population sizes, selection is stronger in larger population sizes and often drives popn to fixation

inbreeding load

fixation of deleterious mutations in small populations which decreases fitness and can lead to extinction

what is the neutral theory of molecular evolution

genetic variation within and among species is primarily due to random genetic drift of mutant alleles that are selectively neutral

discrete traits

traits with clearly outlined character states

quantitative traits

traits that have polygenic inheritance, multiple loci that code for a trait and varies continuously

directional selection of a quantitative trait

moving the mean one way or another

stabilizing selection of a quantitative trait

decreasing the space around the mean, squishing in on ideal values

disruptive selection of a quantitative trait

favours either extreme so increases the overall population variability

how do we measure trait selection strength

relative fitness vs trait value

evolvability (e)

ability for a trait to evolve

what is QTL

quantitative trait loci, regions of genome that affect quantitative traits

what are SNP

single nucleotide polymorphisms, looking for changes in certain DNA bases to understand how phenotypes arose

what does convergent evolution at QTL look like

when a gene encodes for the same thing in multiple lineages

what is local adaptation

traits that thrive in a local population that increase fitness in the area

what is local selection

selection for locally adaptive traits

what is FST

variation between subpopulations, 0: popn have same allele frequency 1: popn are fixed for different alleles

what are the two measures of gene flow

discrete patches and spatially continuous

gene flow and HWE

if huge population shows up with new allele will end up with a lot of homozygotes as the new inhabitants breed with eachother

what is gene swamping

new genes from migrants making homozygotes of a new allele most common which disrupts local variation and selection

How does local selection act on a popn

local selection moves to make populations more different

how does gene flow affect genetic variation within a population

it will act to decrease local genetic variation

what ways can species react to climate change

range shifts, adaptation using pre adaptation possible due to latent variation

BSC

biological species concept, a group of organisms that can interbreed with eachother and are somehow isolated from other groups

what is the phylogenetic species concept

species are distinguishable phylogenetic lineages

what are some pre zygotic reproductive isolation barriers

behavior, environment and sexual, non matching gametes, mechanical

what are some examples of post zygotic reproductive isolation barriers

gene pairing, chromosomal abnormalities

what are DMI

reduction in hybrid fitness, negative interactions between alleles from either parent