Evol Bio exam 2

• 1. Variation in environments they experience. Genetic variation in environment. different environments have different selection pressures.
• 2. Not just a strick one genotype-phenotype relationship. the impact multiple alleles have on a phenotype

• Use equation Var(P) = Var(G) + Var(E) if p and g are independent. 
• Conduct an experiment in which the environment is negligible, such as in a greenhouse.

• Heritability is “vague”, a misleading term. Selection can only occur if the variation of the trait is heritable.  Var(G)= represents the type of genetic variation present in a population Heratible is not the same as heritability. Heritability: proportion of variation in a characteristic is due to genetic variation among individuals in a particular environment. (Has nothing to do with passing a trait to offspring)
• (the percentage of overall variation that is due to genetic variation)

• 1. Continued selection exhausts additive genetic variation. (plateaus)
• 2.since genetic variation decreases due to the promotion of the desired trait increases in presence over time, heritability also decreases since genetic variation and heritability are proportionally related to each other.

• 1.when much of total variability is due to additive genetic effects, the response to selection can be rapid and strong.
• 2. Little additive genetic variance implies a poor response to selection.

• 1. Rate of evolution would depend on only rare variants from the wild type if there was minimal genetic variance.Rate of evolution is not limited to the rare occurrence of a variant of a wild type gene, therefore has more of a chance to evolve adaptive traits. Therefore rate of evolution increases with increased genetic variation,
• 2. until a certain point. If there is too much genetic variation, there can be a large removal of the population if there are many low-fitness traits. 
• 2. more alleles

Germ line mutations: more important for evolution since these are transmitted to the next generation, and reproductive fitness is what carries evolution. Telomeres do not shorten for germ line dna.  

Somatic mutations: effects the function of individual organisms. Can be influential in evolution with plants and fungi who do not have a germ line. Thus somatic mutations are inherited and play a role in evolution.

Isogamous: Mechanism: fusion of gametes that do not differ in size/shape and no male/female distinction. However they can differ in other ways.  Each gamete in sex always does play a different role. Can have more than one gamete type. Labeled as + or -, A or a. mating can only happen between these different types. Ex/ various mushroom species. Timing of evolutionary origin: Occurred first. 

Anisogamous: Mechanism: two gametes fuse that have different sizes and shapes. The big, scarce gametes are female and small, numerous gametes are male Timing of evolutionary origin: evolved from isogamy. This can also be phrased as the “derived state” whereas isogamy is the “ancestral state”

Anisogamy was selected due to difference in size. Since there was a difference, optimal sex and fetal development was obtained by each gamete specializing into roles.  The effect of this is the egg development investing in a lot of resources.  Since eggs are now expensive and sperm cheap, this creates eggs to somewhat be the bottleneck of reproduction (having lower lifetime reproductive success).  This causes females to be more choosy and males to compete. Primary and secondary sexual characters have been shaped by sexual selection

• The two-fold reproductive disadvantage
• 1.  Asexual females potentially produce twice as many daughters as sexual females. A mutation that suppresses meiosis and allowed eggs to develop without fertilization would enjoy a two-fold increase relative to its standard sexual allele, if sexual and asexual females produce on average the same number of offspring Sex opens the door to nuclear meiotic drivers and selfish cytoplasmic genes Strict asexual reproduction implies co-transmission of all genes, nuclear and cytoplasmic while sexual reproduction implies that chromosomes and alleles segregate and recombine in every generation allowing possible spread of mutants that cause unfair transmission at the expense of their non-mutant colleagues 
• Recombination both creates and destroys favorable gene combinations

Non-random: some parts of the genome are more susceptible to mutation, and in addition susceptible to a more frequent rate. Random: there is no relationship in place between phenotypic effect and actual needs of organism.

duplication (not replication, when two copies of gene A are in population) does not hinder existing gene and its ability but allows for another trait to be adapted that is similar but takes on a different role (ex/ globin genes, )

The process of recombination over multiple loci can create phenotypes outside of the current spectrum of phenotypes present.

If substitution does not alter the amino acid sequence, it is synonomous If substitution DOES alter amino acid sequence, it is NON-synonymous. These are more associated with selection, greater chance of affecting organisms’ fitness.

• Neutral evolution: mutations causing variation and genetic drift that reduces it. 
• Size of pop is a factor: smaller the population, the greater the impact of genetic drift.
• Adaptive: mutations increase diversity, selection decreases diversity.

When allele reaches fixation, it becomes the only allele in the population.  The rate of new mutation is only one person in the population of the world. The rate at which this mutation grows to impact the world is , only for neutral mutation. (2 comes from diploid).

When allele reaches fixation, it becomes the only allele in the population.  The rate of new mutation is only one person in the population of the world.** this doesn’t really make any sense The rate at which this mutation grows to impact the world is , only for neutral mutation. (2 comes from diploid).  (one allele has the probability 1/2n to be fixed) 1 -  1/(2N) probability that neutral mutation will be lost, so most neutral mutations are lost. One allele sooner or later will reach fixation due to genetic drift

• 1. (In other words new alleles appearing, old alleles disappearing. Talks about new allele balance) 
• 2.Mutations: add new alleles to population. 
• 3. Genetic drift: removing alleles from pop. 
• 4. Therefore a continual flux.  Genetic drift weeds out new alleles slowly in a large pop. 
• 5. As explained earlier, the likelihood of an allele lost is high due to the “equation of probability of losing the allele”

• 1.Ex/ “lighter skin” mutation happened twice. Once in European population, second in Asian population. 
• Ex/ bacterial. Generation is high, so same mutation is likely to be regenerated over and over.  jQuery112406884652548398862_1553719497578?
• Q=µ/s Deleterious mutations occur at same rate of general mutation rate. 
• µ = mutation rate 
• s = selective disadvantage 
• when s is little , frequency of mutation is higher, due to a weaker selection removing mutations

1.Ex/ “lighter skin” mutation happened twice. Once in European population, second in Asian population. Ex/ bacterial. Generation is high, so same mutation is likely to be regenerated over and over.  jQuery1124039231679681597176_1553740281558?Q=µ/s Deleterious mutations occur at same rate of general mutation rate. µ = mutation rate s = selective disadvantage when s is little , frequency of mutation is higher, due to a weaker selection removing mutations