UNIT THREE Flashcards
what does natural selection need to succeed?
heritable variation
excess production
differential success
what did Linnaeus do?
“father of taxonomy” proposed nested classification of genus, genus, family, order, etc
what did Lamarack do?
observed progression of species in fossils (suggested modification)
said that the world has separate lineages that strive for perfection/complexity by using the use and disuse of parts and inheritance of acquired characteristics (this is not well supported)
examples of natural selection?
- warfarin use (stops blood clotting) increases gene mutation that causes warfarin resistance in rats, even though the mutation is harmful (shows editing rather than creative mechanism and time/place contingency)
- soapberry bugs feed on juice inside fruit, they developed shorter beaks when flatter fruit became more common
evidence of a tree of life?
vestibular structures
molecular homologies (similarity from a common ancestor)
biogeography
the fossil record
what are vestibular structures?
structures that have little to no function are are derived from a more complex structure (hind-limb bones in whales)
what is an example of a molecular homology?
the universal genetic code
what is biography in evolution?
some taxa are restricted to one location (endemic because of a common ancesto
what is a population?
an interbreeding and interacting group of a species
what are the two types of gene pools?
polymorphic loci (two plus alleles at differing frequencies)
fixed alleles (home population is homozygous at locus)
what is the Hardy-Weinburg principle?
p2 + 2pq + q2 = 1
(if this works the population is at Hardy-Weingburg equilibrium)
what are the assumptions for the Hardy-Weingburg principle to work?
new generation’s alleles are the same as the parent generation’s
no mutations
no natural selection
no migration
very large (infinite) population size
random mating
how does genetic variation happen?
mutation
gene flow (other populations)
microevolution
what are the types of mutation in evolution and how common are they?
neutral - most
deleterious - some
beneficial - very few
what is microevolution?
change (fixation or loss) in allele frequencies over generations
what are the causes of microevolution?
natural selection
gene flow
genetic drift
genetic bottlenecking
what is genetic drift?
random changes in frequency that can lead to fixation or extinction
(more common in smaller populations, chance of fixation = frequency (theoretically))
what is genetic bottlenecking?
when the population gets very small which causes low genetic diversity
what is the founder effect?
after genetic bottlenecking rare alleles become much more common
what is selection pressure?
what is placed on the “bad” genes
what is relative fitness?
what the “good” genes have
what is polygenic inheritance?
when one phenotype is influenced by multiple genes
what is quantitative character?
a smooth range of phenotypes
what is directional selection?
when one end is selected against (often caused by environment changes)
what is stabilizing selection?
when the extremes are selected against (often caused by opposing selective forces)
what is disruptive selection?
intermediates are selected against (role in some speciation events)
what is sexual selection?
when organisms compete for mating abilities
what is intrasexual selection?
competition with one sex (men) for mating abilities
what is intersexual selection?
one sex (women) choose mate from competitors
what is sexual dimorphism?
an adaptation that benefits one sex but both would suffer potential survival costs
what is speciation?
when populations of one species evolve separately to become separate species
what is allopathic speciation?
geographic barrier blocks gene flow, new habitat with different natural selections
what happens when species with partial reproductive barriers established create hybrids?
fusion
reinforcement
long lasting hybrid zone
what is fusion in speciation?
two species produce high fitness hybrids and merge into one species
what is reinforcement in speciation?
two species create low fitness hybrids and natural selection ends hybridization and species stay separate
what is the long-lasting hybrid zone?
hybrids of the two species are uncommon or have variable fitness
what is sympatric speciation?
new species evolving within one geographic location, like parasites host switching or disruptive selection that favours reproductive barriers
what is polyploid speciation?
when two species have usually sterile/unviable hybrids but have a mitotic error that makes the hybrids viable/fertile and the form new species
what is one exception to the tree of life?
polyploid speciation
what are reproductive barriers?
inhibit gene flow, may arise accidentally or evolve through natural selection
what are the two types of reproductive barrier?
prezyogtic (before fertilization) and postzygotic (after fertilization)
what are the types of prezyogtic barriers?
habitat isolation
temporal isolation (mate at different times)
behavioural isolation
mechanical isolation (no fertilization occurs)
gamete isolation (no zygote produced)
what are the types of postzygotic barriers?
hybrid inviability
hybrid infertility
hybrid breakdown (second generation of hybrids are inviable/infertile)
what are systematics?
study of the diversity of life
what is taxonomy?
the study of classification
what are the two types of phylogenetic tree?
cladogram - branch lengths don’t matter
phylogram - branch lengths represent inferred amount of evolutionary change
what is a monophyletic group?
an ancestor and ALL descendents
what is a paraphyletic group?
an ancestor and SOME descendants
what is a polyphyletic group?
two or more groups artificially grouped together without common ancestors
what is cluadistic reasoning?
examine different characteristics and make character matrix or table to see shared derived states (imply relationships)
what is convergent evolution?
two similar species developing separately with no common ancestors
what is parsimony?
the theory that the most correct phylogenetic tree has the fewest evolutionary changes
what is the fossil record?
provides info on past ecosystems and is found in sedentary rock
index fossils = useful for dating
what are the eras in the phanerozoic eon?
paleozoic
mesozoic
cenzoic
what is the geological record?
the earth is 4.6 b years old, microbial life arose 3.5 b years ago, animals and plants developed 550 m years ago
what is the end-permean mass extinction?
about 250 million years ago
90% species extinct
50% families extinct
what is the end-cretaceous mass extinction?
about 65 million years ago
50% species extinct
dinosaurs
what are adaptive radiations?
rapid speciation events in underexploited habitats, can be regional (50+ plant species from 1 ancestor in Hawaii) or worldwide (after mass extinctions)
what are complex adaptations?
functioning intermediates
modification of existing structures
larger (than darwinian) steps like gene duplication
what is an example of developmental regualtion?
mutations in developmental genes
example: homeotic genes (homeotic fruit flies have two torsos)
genes can duplicate in chromosomes and have independent evolutionary change (paralogs)
what is the three domain scheme?
bacteria, archaea, and eukaryotes (most all microbial, fist two are prokaryotic)
what are prokaryotes?
3.5 b years old, are most of the biological activity in many ecosystems
bacteria and archaea
what are some types of bacteria?
spirochetes
gram-positive bacteria (no outer membrane)
cyanobacteria (photoautotrophs)
proteobacteria
what are bacteria’s cell envelople
and outer membrane, plasma membrane, and a peptidoglycan wall in between
what are archaea?
most are extremolphiles or methagens
have no outer membrane or peptidoglycan wall
how did eukaryotic cells evolve from prokaryotic cells?
endomembrane system evolved conventionally
endocybiotic alphasproteobacterium becomes the mitochondrion
endosymbiosis cyanobacterium becomes the plastid
what are protists?
they are prokaryotic cell’s main predictor, they causes disease, and can photosynthesize
what was the most recent era?
cretaceous era
what is a shared trait between archaea and eukaryotes?
organelles of endosymbiotic origin
what did the genome of a plastid evolve from?
the genome of a cyanobacteria
