unit 8-natural selection Flashcards
evolution
a change in gene frequency over time
change of organisms over time
adaptation
trait shaped by natural selection that increases an organism’s reproductive success in a particular environment
descent with modification
identified hat species on earth today descended from ancestral species
natural selection
“survival of the fittest”
process where individuals that are best fit for their environment survive to reproduce
(the change in groups of organisms through time)
how old is the universe
15 billion years old
how old is the earth
4.5 billion years old
how long has there been life on earth
3.5 billion years
how long has there been humans
150,000 years
4 basics of natural selection
- individuals show a variety of genes
- variations pass from parent to offspring
- more offspring are produced than the environment can support
- variations that increase reproductive success will be more likely to be passed on
darwin’s
collected specimens and observed finches to develop two main points- descent with modification & natural selection
evidence for evolution
- the fossil record
- comparative anatomy
- comparative embryology
- comparative biochemistry
- geographic distribution
fossil record
chronological collection of life’s remains in the rock layer (old on bottom, new on top)
fossils
preserved remains of marking left by organisms that lived in the past
(found in sedimentary rock)
derived traits (newer)
newly evolved features (feathers)
they dont appear in the fossils of common ancestors
ancestral traits (older)
primitive reatures (teeth/ tails) appear in older fossils
comparative anatomy
relationship between the structure of ancient species and modern species
three parts of comparative anatomy
- homologous structures
- analogous structures
- vestigial structures
homologous structures
similar structures inherited by a common ancestor
Ex. arms/ wings
analogous structures
structures used for the same purpose and have similar features but aren’t inherited from the same ancestor
(Ex. wings- needed to fly but evolved separately)
vestigial structures
structures that are reduced forms of functional structures in organisms
(things that don’t really work anymore)
(Ex. human appendix)
comparative embryology
pre birth stage of an organisms development
(same during certain phases of development but become different structures in adults.
(Ex. humans and rabbits look alike as an embryo)
comparative biochemistry
the macromolecules organisms are made out of DNA, proteins, fats, carbs
the more DNA two organisms have in common, the more similar they are
(Ex. humans have 98% DNA common with chimps and 68% with moths which make us more similar to chimps)
geographic distribution
similar species of organisms that are geographically closer share more common characteristics
(patterns of migration explained the relationships)
biological fitness
measure of the relative contribution an individual trait makes to the next generation
(measurement of how many can reproduce)
population
a group of individuals of the same species living in the same area at the same time
what did Darwin realize in the Galapagos
- all species tend to produce excessively
- resources are limited.
variation
the differences among members of the same species
artificial selection
the selective breeding of domesticated plants and animals to produce offspring with genetic traits that human value
(Ex.dogs)
gene pool
all of the alleles in all the individuals that make up a polulation
microevolution
evolution on the smallest scale
generation change in the frequencies of alleles within a population
Hardy Weinberg principle
connection will not occur in a population unless allelic frequencies are acted upon by forces that cause change
equilibrium- p2+2pq+q2=1
5 conditions of the Hardy Weinberg principle
-population has to be large
-no immigration & emigration
-mating is random
-mutations do not occur
-natural selection does not occur
(to be at equilibrium, all conditions must be maintained)
genetic drift
any change in the allele frequencies in a population that is due to chance
types of genetic drift
founders effect & bottleneck
founders effect
small amount of organisms from a population become isolated from other populations. those traits are passed along which can lead to a change in frequency
bottleneck
when a population declines to a very low number
other causes of change in gene pools
- gene flow (an exchange of genes between populations)
- mutation
4 patterns of natural selection
- stabilizing
- directional
- disruptive
- sexual
stabilizing selection
eliminates extremes- assuming the “average” organism (produces more offspring)
directional selection
allele frequencies shift in one direction
disruptive selection
population is split into 2 groups
individuals of 2 extremes survive
sexual selection
the more attractive to the opposite sex, the more likely one is to reproduce and pass on those genes
antibiotic
medicine that kills or slows the growth of bacteria
species
a group of organisms capable of interbreeding and producing fertile offspring
speciation
the creation of new species
types of speciation
allopatric & sympatric
allopatric speciation
a physical barrier dividing two or more populations (geographic isolation)
sympatric speciation
a species evolves into a new species without a physical barrier (more in plants) (reproductive isolation)
reproductive isolation
prevents gene flow among populations
types of reproductive isolation
prezygotic & postzygotic isolation
prezygotic isolation
(before fertilization) prevents reproduction by making fertilization unlikely
postzygotic isolation
(after fertilization)
prevents reproduction because “hybrid” species is infertile
when would speciation occur
a population must diverge and then become reproductively isolated in order for a new species to form
patterns of evolution
- adaptive radiation
- coevolution
- convergent
adaptive radiation
(divergent evolution) diversification of a species into a number of different species in a relatively short period of time
(follows mass extinction)
coevolution
(mutualism)
species evolve in close relationship with each other
convergent
unrelated species evolve with similar traits
environments are far apart but ecology and climate are similar
gradualism
theory that evolution occurs in small, gradual steps over time
punctuated quilibrium
theory that evolution occers with relatively sudden periods of speciation followed by long periods of stability
early atmosphere
gases came from volcanoes
(H2O, CO2, SO2, CO, H2S, HCN,etc)
little oxygen available
fossils
preserved evidence of an organism
found in sedimentary rock
categories of fossils
- trace (indirect- feetprint)
- molds/ casts (impression)
- replacement (crystals)
- petrified (pore spaces filled)
- amber (tree sap)
- original material (mummification or freezing)
dating fossils
relative & radiometric
relative dating
used to determine the age of a rock by comparing them with those in other layer
radiometric dating
uses the decay of radioactive isotopes to measure the age of a rock
half life
the amount of time it takes for half of the original isotope to decay
geological time scale
model that expresses the major geological and biological events int he earths history
(eons, eras, periods, epoch)
eons
precambrian eon
90% of the earths history
paleozoic era
first vertebrates appear
(major diversification of most majoy animal groups
mesozoic era
first mammals appear
-dinosaurs and birds appear
cenozoic era
monkeys, apes, and modern humans appear
continental drift
movement of continents about earths surface.
the first cells
probably prokaryotes (bacteria)
endosymbiont theory
small aerobic prokatyotes were ingested by larger ones. created a mutualistic relationship
mass extinction
episode of great species loss
taxonomy
identification, naming, and classification of species
binomial nomenclature
each species has a “first & last” name
created by carolus linnaeus
classification for taxonomy
Life, Domain, kingdom, phylum, class, order, family, genus, species
(king phillip chocked on four gob stoppers)
scientific name
genus & species
convergent evolution
a process in which unrelated species from similar environments have adaptations that seem very similar
phylogenetic tree
a branching diagram that represents the proposed phylogeny of evolutionary history of a species or group
cladogram
a phylogenetic diagram that specifies the derived characters of clades
domain
bacteria, archaea, eukarya
kingdoms
eubacteria, archaebacteria, protists, fungi, plantae, & animalia
domain bacteria
eubacteria
prokaryotes
domain archea
archaeabacteria
autotrophs & hetertrophs
domain eukarya
protista, fungi, plantae, animalia
(eukaryotic cells
kingdom protista
- eukaryotic organisms
- do not have organs
(ex. algae)
kingdom fingi
-absorbs nutrients from environent
hyphae
threadlike filaments that make up a fungus
kingdom plantae
- all multi cellular
- have cell walls
- plants
kingdom animalia
- heterotrophic
- multi celled
- eukaryotes
viruses
nucleic acid surrounded by a protein coat
