Evolution 3 exam

saltationism

evolution seems to happen quickly even in a generation

gradualism

slow change

meiotic drive

causes rapid evolution due to biased gamete formation/ an exception to medels law

normal inheritance

frequency of the allele depends on selection, drift, random change

gene drive inheritance

frequency of the allele grows exponentially and fixes rapidly

whole genome duplication

a massive chromosomal mutation yielding triploid (3n), tetraploid (4n), hexaploid (6n)

autopolyploid

diploid parents same species

allopolyploid

diploid parents different species

polyploid

species with more than the diploid complement of genomes

lineage

continuous line of entities connected over time through ancestor descendent relationships

sister relationships

relationships descending from the same parent lineage

parent

node is the immediate ancestor of a node

daughter

nodes are the immediate descendent of a node

extant lineages

lineage that survive to the present

splitting/branching

changes in the information flow

monophyletic group

any group on a phylogeny that consists of a particular lineage and all its descendants

also known as a clade

autoampomorphic

character that are unique to a particular lineage

synapomorphic

characters shared within groups of lineages that arose in and was inherited from their most recent common ancestor

plesiomorphic

characters that arose in and inherited from an ancestor older than the most recent common ancestor

shared with a wider group of lineages

homology

we expect lineages that have shared common ancestry to share some biological characters inherited from their common ancestor

homoplasy

similarity can arise due to parallel or convergent evolution

ontology

the study of being (what species are)

epistemology

the study of knowledge (diagnosing species)

gene flow

ties members of the same species together

isolation

disruption of gene flow

divergence

evolution of reproductive incompatibilities/isolation

speciation

process by which new species arise from ancestral ones

disruption of gene flow or isolation

initial splitting event where gene flow within an ancestral population is disrupted one lineage branches into two

evolution of reproductive barriers

pre and post zygotic barriers develop to prevent gene flow between individuals of different daughter lineages even if they come in contact again

allopatric speciation

populations separated by extrinsic physical barriers

barriers include mountains, rivers, land forms, currents

most common mode

parapatric speciation

geographic adjacent populations diverge without an extrinsic barrier

involve cline and hybrid zones

cline

spatial gradient in frequency of phenotypes/ genotypes as a result of different selective conditions

hybrid zones

source of gene flow undermining speciation countered by disruptive selection

sympatric speciation

reproductive isolation evolves within a population an extrinsic barrier

rarest mode of speciation

intermediate genotypes act as a conduits gene flow

peripheral isolated model

special case of allopatry where one of the populations that develops into new species is very small

founder effect

genetic drift more important mechanism in evolution of reproductive isolation in peripheral isolated model (due to smaller population size of one of the daughters)

vicariance

gene flow disruption by barrier rising up between organisms (daughter populations can be large or small)

dispersal

gene flow disruption by organisms moving across barrier (typically very small founder population size, maybe a single individual)

prezygotic reproductive barriers

aspects of genetics, behavior, physiology, ecology of a species that prevent sperm from one species from fertilizing eggs of another species

reduce likelihood that a zygote will form

postzygotic reproductive barriers

aspects of genetics, behavior, physiology, ecology of a species that prevent zygotes from successfully developing and reproducing themselves

positive frequency dependent selection

where the fitness of a phenotype increases with its frequency

negative frequency dependent selection

takes place where rare genotypes have higher fitness than common genotypes

this process maintains genetic variation within populations

positive selection

selection for a particular allele or trait (typically beneficial)

negative selection or purifying selection

selection against a particular allele or trait (typically deleterious)

natural selection

theory that explains the observation of evolution (change in life patterns)

main mechanism for evolution of adaptive character or traits of an organism

acts on standing inheritable variation

acts on phenotypes arising from genotypes

standing

the traits must be present

inheritable

the traits must be passed down to descendants

variation

the traits must vary enough with respect to fitness to result in differential reproductive success

evolution

variation + differential survival/reproductive success +inheritance =

pleiotropy

a single gene can have effects on multiple aspects of phenotype