Midterm 1 (Ch. 25-28) Flashcards
Node (phylogenetic tree)
where ancestral lineage splits
Tip (phylogenetic tree)
recently evolved; can be species but doesn’t have to be
Properties of living organisms (5)
- made of cells (cell theory)
- use energy to stay alive and reproduce
- process info to respond to ext. and int. environment
- reproduce/replicate
- products of evolution
Proximate question
mechanistic question (how does it work)
Ultimate question
evolutionary (why and how does it exist)
Parts of scientific method
observation, hypotheses, predictions, test predictions (experiment), conclusions
Null hypothesis (H_0); what is it and how is it used
- thing being tested has no effect, or that there is no pattern other than chance (random) effects
- try to prove predictions by disproving (rejecting) null hypothesis
Inferential statistics
compare data to null hypothesis of no pattern or chance pattern
Homologies (and types)
similar traits due to shared ancestry (can be genetic or development)
Structural homology
similar structures across related organisms despite different functions
Evolutionary lineage
one or a series of ancestor-descendant relationships, often in context of evolutionary tree
Speciose (adj)
species-rich
Speciosity (n)
measure of how many species are in a group
speciate (v)
ancestral lineage evolving into one or more different descendant lineages
Darwin’s four postulates
- variation among individuals of a population or species
- at least some heritable traits
- struggle for existence: more offspring produced than can survive
- certain kinds of individuals produce more surviving offspring
VHS Center
Natural selection
mechanism of evolution; populations change when individuals with certain heritable traits have more surviving offspring because those traits help the parents survive and reproduce
Adaptations
“fit” between organism and its environment (produced by natural selection)
Fitness
measure of ability to survive and create viable offspring
Mechanisms of evolution (name them)
Natural selection, genetic drift, mutation, gene flow
NGMG
Genotype frequency
frequency of homozygous and heterozygous genotypes in population (e.g., MM, Mm, mm)
Allele frequency
frequency of each kind of allele (e.g., M, m)
p (HW)
frequency of dominant allele
p=freq(AA) + 1/2 freq(Aa)
q (HW)
frequency of recessive allele
q=freq(aa) + 1/2 freq(Aa)
HW frequency of homozygous dominant genotype
p^2
HW frequency of heterozygous genotype
2pq
HW frequency of homozygous recessive genotype
q^2
HW assumptions (5)
- random mating
- no genetic drift (population must be infinite)
- no gene flow (no immigration/emigration)
- no mutation
- no natural selection
Geneticist definition of ecolution
change in allele frequencies over time
Violations of HW lead to____.
evolution
Genetic drift
evolutionary mechanism; comes from sampling error (sample of gametes leading to a generation may not be representative of parent population allele frequencies); larger effect in smaller populations
Kinds of nonrandom mating (2)
Inbreeding and sexual selection
Inbreeding changes ____ and not _____; decrease in _____.
genotype frequencies; allele frequencies; heterozygotes
Inbreeding depression
lower fitness due to higher than HWE frequency of expressed deleterious alleles
Directional selection
one extreme has higher fitness
Stabilizing selection
intermediate value has higher fitness
Disruptive selection
intermediate value has lowest fitness
Balancing selection
variation maintained through: heterozygote advantage and frequency dependent selection
Frequency dependent selection
rare genotype/phenotype has highest fitness
Which mode of selection increases genetic variation?
disruptive selection
Gene flow
migration (immigration and emigration) introduces alleles from other populations, reducing differences between or among populations
Mutation
source of all genetic variation; introduces new alleles into a population
Morphological species concept (MSC)
species are groups of organisms that look similar to each other
Polymorphic species
many kinds within a species
Sexually dimorphic species
males and females look different
Cryptic species
separate species that look nearly identical
Biological species concept (BSC)
species are reproductively isolated
Prezygotic isolation
individuals can’t mate
Postzygotic isolation
hybrid offspring don’t survive or reproduce
Phylogenetic species concept (PSC)
species are single evolutionary lineages; smallest monophyletic group on a phylogenetic tree
Synapomorphy
shared, derived character
Allopatric speciation
physical, generally geographic isolation
Founder effect
small population taken from larger population to start new population (genetic drift)
Vicariance
physical splitting of population
Reinforcement
selection favoring pre-zygotic isolation
Sympatric speciation
species from common ancestor in same place
Order of taxonomic ranks
domain, kingom, phylum, class, order, family, genus, species
Symplesiomorphy
shared trait but not derived; shared due to older common ancestor
Homoplasy
convergent evolution; similar characteristics but not bc of shared ancestry
Paraphyletic group
doesn’t include all descendants of a common ancestor
Polphyletic group
doesn’t include most recent common ancestor
Natural taxon
monophyletic group
Eras in Phanerozoic Eon
Paleozoic, Mesozoic, Cenozoic
Start of Paleozoic era
Cambrian explosion
Adaptive radiation
rapid diversification of organisms to fill ecological niches
Criteria for mass extinction
at least 60% of species go extinct
Permian extinction (at end of Permian); rate
at least 90% of all species lost
Genetic bottleneck
sudden reduction in the number of alleles in a population (genetic drift occurs)
