-560-540mya-southern Australia-sponges, jellies, comb-jellies, burrows and tracks (imprints)-No hard shells, limbs or heads with feeding appendages
inherited characteristic that increases an organism's chance of survival.
-Oldest 580-570mya-southern China-microscopic sponges and embryos-likely all filter feeders
change within a lineage
-develop inside female-vascular plants: result diploid sporophyte is independent-non-vascular plants: diploid sporophyte is dependent -> two generations connceted togehter
(2) Positive frequency-dependent selection
Positive frequency-dependent selection: the common phenotype is favored, fixed.
Different populations may become fixed for different phenotypes.
Example: Müllerian mimicry: several unpalatable species share a similar warning pattern (butterflies). Transplant experiments show that survival rate goes down if a butterfly is moved to a region where it does not look like the majority.
expect to lose variation.
Zygote never forms-disruptions: temporal (bad timing), spatial (wrong place)-Gamete barrier: can't fuse together-Mechanical: physically cannot mate-Behavioral: incompatibility
-MHC (major histocompatibility complex) ... scent relatedness (do they smell like you?)
Self imcompatability genes
-in small populations, avoidance is not possible
*Non-random mating can result in changes in allele frequencies, but not directly
nonrandome mating --> genotype frequencies -->phenotype frequencies --> selection
******nonrandom mating on its own does not result in evolution
|Quantitative Genetics measures:||
1)heritabiilty of variation
-to predict response to selection
7 clones of Yarrow from Mather population transplanted at 3 altitudes
-measured after 3 years
-higher altitudes = shorter plants
Alternate forms of a single gene
• Prokaryotic cells• But: rRNA sequences more similar to eukarya– Signature sequences– But actual relationships confused by lateralgene transfer• Lateral gene transfer:– Plasmids– Viruses– Uptake of DNA by transformation
geologist, fried of darwins. uniformitarianism.
|What is "D"?||
Coefficient of Disequilibrium
= (p1q1 x p2q2) - (p1q2 x p2q1)
Formation of new species from pre-existing species
organisms desire change; use vs. disuse; acquired traits can be passed on to offspring; led Darwin to believe organisms can change according to environment
within the context of evolution, individuals with advantageous or adaptive trait tend to be more successful than their peers reproductively
-may create new allele
-caused by random error during either DNA synthesis or repair
If mutation is in coding region:
-replacement/non-synonymous (a.a. substitution)
-silent/synonymous (no a.a substitution)
-can have base-pair substitution (no effect on a.a sequence, missence, or nonsense)
nonsense = insertion of stop codon
missense= difference a.a.
-can have base pair insertion or deletion (frameshift cause extensive missense, frameshift cause immediate nonsense, insertion or delection of 3 nucleotides ields no frameshift)
-typically far more synonymous nucleotide substitutions occur than non-synonymous
Movement of individuals into a population.
Charles Lyell’s idea that geologic processes have not changed throughout Earth’s history
came up with Natural selection, influenced by his studies on the Beagle voyage, and influenced by Lyell
|Dominant (medelian inheritance)||
Trait expressed in heterozygous state
study of the evolutionary history of the species
is the response evolution of one species to neew adaptations that occur in another species. For example, if a prey adapts to move more quickly, those predators selected for faster mobility would pass on the trait as they feed and proliferate and create more of the faster predators.
alteration in the timing of cell processes.
allele frequency fluctuation from one generation to the next increases in small populations; can result in a loss of variety across entire genome over time
|DDT was once considered a "silver bullet" that would permanently eradicate insect pests. Today, instead, DDT is largely useless against many insects. Which of these would have been required for this pest eradication effort to be successful in the long run||
-during pleistocene epoch - a very high proportion of large-bodied mammals and birds became extinct -might have succumbed to changes in climate and habitat-most likely weapon-wielding humans
-An evolutionary trend towards one extreme-changes in characteristics of a population by favoring individuals that vary in one direction from the mean
|Cambrian explosion phyla||
porifera, cnidaria, cterophora (comb jellies), platyhelminthes, nematoda, arthropoda, annelida, mollusca, echinodermata, chordata
|Process of Evolution||
mutation-- natural selection-- new trait either doesn't survive or is slowly incorporated into the population(mutation-natural selection-time)
|survival of the fittest||
carryin capcitycompeition food, territor, water mates differental survival and reproduction surviors passon genes to next generation
|Intraspecific Brood Parasitism||
Increase costs incurred from non-kin
-50% chicks/nest die
-varation in egg colour
-females can disriminate eggs
-what happens to female's offspring when other females lay eggs in nest
When female cannot discriminate, more parasitic eggs... and fewer of own.
|example of discrete trait||
pod shape in peas
any aspect of structure or functioning that prevents successful interbreeding
the appearance of apparently similar structures in organisms of different lines of descent.
A kind of cell division that produces the sex cells, each of which has half the number of chromosomes found in other cells of the organism.
(+,0) one benefits, one not harmed (ex remore fish and shark, barnacles and whale)
Traits obtained later in lifeThey are not genetic.
|Sources of Variation||
ultimate source is mutations than sex
Describe environmental variance:
give an example
portion of Vp (phenotypic variance) that results from RANDOM, environmentall induced variation among individuals. Could also be from experimental error.
example: beak length may be influenced by chance differences among individuals in energy acquisition (food supply, in utero enviro etc)
|Origin of Mammals:synapomorphies of mammals||
-Lactation (not fossilized)-Single lower jaw bone-hair-unique jaw articulation-three bones in the middle ear-differentiated teeth
Pattern of evolution in which long stable periods are interrupted by breif periods of more rapid change.
smooth vs. wrinkled (Mendel's peas) - one of only several choices
|Why does heterozygosity decrease? (drift)||
Max heterozygosity occurs whenfrequency of both alleles is 50%
-107 populations... 8M and 8F in each pop (16N)
-All hetero for brown gene (bw75/bw)
-**3 phenotypes for this locus
-created multiple bottlenecks through subsampling (kept removing 8/8(16) from each consecutive population)
-by 19th generation, bw75 was fixed in 28 populations and lost in 30 populations
-heterozygosity decreased on average
-most populations lost genetic diversity
***heterozygosit decreased at a faster rate than expected!
-census population was 16 (not all individuals reproduced!)
-effective population was 9 (average)
|what body structure did Darwin use the most for comparative anatomy?||
Meiosis and crossing over. One allele from each parent.
Prinacble that all living things were descended from common ancestors
|Muller's ratchet predicts that||
asexual species experience higher rates of extinction than sexual species
|What evidence of evolution is: humans, unlike rabbits, have no known use for their appendix||
the total genetic information in the gametes of all the individuals in a population.
tree bark turned back to light color and moth population reversed
|Name 4 requirements of natural selection.||
1. Inheritance2. Differential reproductive success3. Overproduction of offspring4. Genetic variation
|Evolution by natural selection requires... (2 things)||
1. Heritable phenotypic variation (differential fitness)
2. Genetic change over successive generations (Δp ≠ 0)
Note: Natural selection is one mechanism that can lead to evolution. It is not evolution!
Evolution can also occur by violating the other H-W assumptions.
Is usually due to some kind of catastrophe that drastically reduces the size of the population. Thus, the continuation of the genes are the responsibility of just a few individuals, and gentic variability is reduced.ex. Elephants seal (hunted, only 1 male left to reproduce)
|adaptations and natural selection||
Organisms are adapted to their enviornment by natural selection.
-specialized claws (grip)
-camo (light belly/dark back)
natural selection: some individuals in a population produce more offspring than others (ie. are more fit)
-not always slow (ie. HIV)
|What is a genotype?||
The genetic makeup of an organism
The individuals at the right and left ends of the graph are the best fit. The individuals in the middle are the least fit. Graph caves in, in the middles or seems to split in two.
|red queen hypothesis predicts that||
asexual species experience higher rates of extinction than sexual species
change of body form from a common anscetor
part of an animals body which is no longer used
Modes of selection
(1) Directional selection
Directional selection favors higher or lower value of a character.
- The mean value of the trait is shifted (if heritable)
- Decreases variation
- bacterial antibiotic resistance
- maize oil content (selected by humans)
- Drosophila bristle number (lab)
- level of activity in mice (lab)
|how is comparative biochemistry proof of evolution||
similar metabolic processes, similar respitory processes, similar enzymes, similar genetic info
|evolution by genetic drift||
faster in small populations than in large
|Geographically speaking, which of the Galapagos islands are still volcanic? Why?||
the western islands are active.
this is because the cracked crust has been shifting from east to west making the Eastern most islands the oldest.
|what are proximate questions? ultimate questions?||
proximate- "how?" questions, ultimate- "why?" questions (how come, what for)
|Faunal and Floral succession, winning the speciation race||
Marine fossil record best illustrates the pattern of major successive faunal assemblages. and similar occurs with plants. This succession is step wise increase in the number of habitats and ways of life occupied, and by a corresponding increase in species diversity. The lineages that win do not do so by competitive displacement but rather by speciating and a higher rate, thereby filling up a larger share of the niches that open up as a result of background extinctions.
|Jean Lamarck: who and what?||
-One of first scientists to states that living organisms change over time.-Developed the Theory of Acquired characteristics (Theory proven INCORRECT.)
|What are some specialities of the galapagos birds?||
picking little seedscracking big seedspoking for alrvaewarbling
|What are the four types of fossils?||
A. compression & impressionB. permineralized (aka petrification)C. casts & moldsD. unaltered remains (ex: amber, ice, peat bogs)
|Descent With Modification||
the theory of Darwin that all of the species living on earth today descended from earlier species.
|what value is used to measure degrees of genetic drift?||
H= avg proportion of heterozygous loci per individual (must be neutral loci aka not selected on)
and avg Heterozygosity (Hbar)
Hbar=avg freq of heterozygotes across all loci genetic variation
|What indicates divergence in a sp?||
One common trait but also two different traits for someother quality. The common trait represents a common ancestor and the different trait represents the divergence.
|What are the two main types of homoplasy?||
1. convergent evolution2. evolutionary reversal
|what are synonymous mutations and nonsynonymous mutations?||
synonymous is when a RNA base change doesn't actually affect the aa that the codon sequences for. this is because of the redundancies in the genetic code. nonsynonymous is the opposite.
|What did the first tetrapods need to develop before they could live on land?||
They needed pelvic and pectoral girdles to sustain their weight on land.
what are the labels on a recombination rate graph?
how does r describe recombination?
x axis = generations
y axis = coefficient of disequilibrium
r=0 means no recombination
r=.5 means rapid recombination
How does mu and Ne effect Heterozygosity?
How do we plot this?
an increase in either Ne or mu will cause and increase in H
We plot this with 4Ne(mu) on the x-axis and Heterozygosity (H) on the Y axis
|why is the rate of neutral evolution unaffected by pop size?||
b/c it is a function of the rate at which neutral alleles enter pops (2Nu) times the probability that these mutations will be fixed (1/2N). pop size cancels out- the rate = 2Nu x 1/2 N= u