Evolution Flashcards
What did Charles Darwin do?
He wrote the Origin of the Species by Natural Selection; which explained how modern organisms evolved over long periods of time from common ancestors
how did meat eating birds evolve to not compete?
Evolved to have different characteristics for different niches
owls: crepuscular to nocturnal (dusk and dawn to night)
vultures: scavenged the kills
hawks: stayed diurnal (day)
Different animals with similar characteristics inhabit___
similar habitats around the world.
Evolution
the process of change over time
two causes of evolution
Natural selection and artificial selection
Natural selection
organisms that have the best characteristics to survive in an environment will live long enough to pass these superior alleles to the offspring and future generations
artificial selection
organism that have the traits that humans want are bred together to give the offspring the desired alleles to pass on to future generations
what did Hutton and Lyell discover that influenced Darwin’s theory?
The Earth must be millions of years old for the geological process to have time to shape it as we see it today
what did Malthus discover that influenced Darwin’s theory?
predicted that human overpopulation would experience war (for resources), famine, and disease. After deaths, the population size would be manageable again. (just like animals)
what did Lamarck discover that influenced Darwin’s theory?
proposed that organisms evolved by acquired traits. What happens to an individual will change its characteristics and this will be passed on to off spring (giraffe necks). this was WRONG trump voice
what did Wallace discover that influenced Darwin to publish his theory?
proposes evolution by natural selection. encouraged and recognized by Darwin.
The struggle for existence
members of a population must compete for limited resources (minerals, air, water, shelter). only a limited number can win.
What do the “winners” of the struggle for existence have?
had the best variations of a characteristic which made them superior in getting resources. they were the fittest
Fitness
how well an organism can survive and reproduce so the alleles for the survivor characteristic are passed on
in a population do all characteristics have a population?
yes. some of these variants are better suited to life in that environment. these will be passed on
adaptation
any heritable (passed on) characteristic that increases an organisms chance to survive and reproduce in a given environment (becomes most frequent allele, even if recessive)
survival of the fittest
the fact that the organisms with the adaptations Best suited for survival for life and reproduction will have the greatest rate of survival
when will natural selection happen
whenever more organisms are born then can survive. the less suited to obtain resources will die
Principle of common descent
suggests that all species come from common ancestors that evolved over time through natural selection as the environments changed around the world
fossils
preserved remains of organisms
descent with modification
natural selection changed more and more of the characteristics in a population until the members didn’t look like the ancestors, they created a new species.
biogeography
tells us where organisms live now and where they lived in the past. patterns suggest environmental factors for evolution
h0m0logous structures
non-similar organisms in related animals. these animals were from a common ancestor population whose members adapted to different habitats. these structures are now used in different ways
divergent evolution
results in homologous organs. the original population spreads out into various habitats that put different environmental selection pressures on the organisms. as organisms adapt to new/different environments their bodies change from the original populations and each offshoot population. (body similar on inside)
analogous structures
body parts that share common function but not structure. the animals are not closely related. don’t share many characteristics
convergent evolution
results in analogous structures. organisms not closely related have similar body parts because they are dealing with the same environmental pressures. (body similar on outside)
Vestigial structures
body parts inherited by ancestors but they have lost most or all of its original function. it didn’t matter if they were there or not. variants with or with out them were just as fit.
ex: wiggling ears, appendix, tail bone
embryological evidence for evolution
exists in the same patterns of embryo development by the HOX genes
molecular evidence for evolution
exists in the common genetic code for shared genes, particularly those for protein synthesis and cytochrome C (all organisms have just in different orders) used in respiration
what are the 7 kingdoms
Animalia, plants, fungus, Protista, Eubacteria, Archeabacteria
KPCOFGS
kingdom, phylum, class, order, family, genius, species
Do environmental pressures act on the genotype or phenotype?
Natural selection; environmental pressures (amount of water, food, shelter, temperature, light, weather) act on expressed traits in the phenotype, not on the alleles
gene pool
all the genes of the population. it will reflect the allele frequency
allele frequency
how many times an allele occurs in the gene pool compared to all the other alleles for the same gene in that gene pool. (how often)
Def of evolution in genetics
evolution changes the frequency that an allele appears in a population
as the organisms adapts and either more or less organisms inherit that form of the trait
are mutations always bad?
no. they can be good bad or neutral. the good ones will be passed more frequently and those organisms are the fittest
how is sexual reproduction good ;-)
gives the best advantage in creating new variants.
some variants have the fittest set of characteristics to survive
what are 3 ways sexual reproduction creates variations
gene shuffling
crossing over
and in bacteria only; lateral gene transfer
gene shuffling
chromosomes move independently during meiosis
crossing over
creates new combinations
lateral gene transfer
bacteria can combine DNA from plasmids and combine genes for various functions to make a bacteria with “new” capabilities than ever existed
Congregation tube
bacteria connect and trade genes through tube during Lateral gene transfer
3 Natural selection patterns
directional selection
stabilizing selection
disruptive selection
Directional selection
Selects for one extreme or the other. majority of the population shifts towards one extreme or side. frequency of allele becomes more numerous
stabilizing selection
most are average, moves towards middle. extremes of trait lessen greatly or go extinct. Most common pattern. Selects for average and against extremes
disruptive selection
“interrupts” flow, average is disruptive. leans towards traits that are at extremes. little variation between two extremes. selects for extremes and against average
genetic drift
Totally by chance. Not natural selection. certain alleles are passed on by chance. Original generation is called “founder effect” because they carry only certain alleles by chance.
genetic equilibrium
the allele frequency in a population stops changing with time. stops evolving. it is perfectly suited to the environment as it is
Hardy- Weinberg principle
an allele frequency in a population should remain constant unless something causes it to change. no evolution unless environment changes.
what are the 5 things that can disturb equilibrium (cause evolution)
nonrandom mating, small population size, immigration or emigration, mutation, natural selection
how does nonrandom mating cause evolution
mates are chosen on the superior quality of a trait. sexual selection. Ex; peacocks, bears, lizards from Galapagos
how does small population size cause evolution
if genetic drift occurs more easily on a small population and has a more dramatic effect on a small population. Ex; flooded beetles story
how does Immigration or emigration cause evolution
changes gene pool by gene flow. individuals entering may introduce alleles and individuals leaving remove alleles
how does mutation cause evolution
introduce new alleles into a gene pool causing a change in gene frequency
how does natural selection cause evolution
if different genotypes result in different phenotypes with different fitness, certain alleles will be selected for and equilibrium will be disrupted
speciation
the process of forming a new species. original population splits into two and becomes separated. they each evolve to their own new environment until they are so different they can no longer interbreed
behavioral isolation
behaviors no longer communicate. Ex; courtship/ mating calls
Geographic isolation
split populations cannot interbreed so as physical differences build up, two species are created
Temporal isolation
life activities occur at different times of day or season. the species can no longer interbreed because of timing
fossil
preserved evidence of ancient life on earth. can be mummified (dry or frozen), in amber, rock, molds.
(best are in sedimentary rocks)
relative dating
compare them to which is above or below them in rock layers. more recent =closer to surface. NO YEARS!!
index fossils
are found in many areas in the same rock layer. they are standard for comparison in relative dating
radiometric/radioactive dating
compares the amount of radioactive element left in a dead organism to the amount that would have been in it when it was alive. this ratio gives age. isotopes decay
half life
the amount of time it takes for half the amount of radioactive sample to disintegrate to harmless form
Carbon14 -> Carbon12
50% = 5770 years
75% =11540 years etc.
2 types of speed of evolution
gradualism and punctuated equilibrium
Gradualism
slow and steady evolution as natural selection produces small changes in allele frequencies thus changes in phenotypes
punctuated equilibrium
no change in gene pool for many generations then suddenly a brief period of rapid environmental change so rapid evolution. no intermediate fossils so its hella confusing
Margulis Endosymbiont Hypothesis
Large prokaryotes engulfed small ones. if the small one provided a service, it was not destroyed. like agario
evidence for Endosymbiont Hypothesis 1
Chloroplast and mitochondria have DNA more similar to bacterial DNA then the DNA found in the nucleus of the eukaryotic cell
evidence for Endosymbiont Hypothesis 2
chloroplasts and mitochondria have double membranes with the inner membrane resembling bacterial cells and the outer membrane resembling the cell of which they are a part
evidence for Endosymbiont Hypothesis 3
when the eukaryotic cell divides by mitosis, the organelles (chloroplast and mitochondria) divide by binary fission like bacteria- the prokaryote
