BIOL3045 Study Guide - Final Guide: Vasoconstriction, Histone Deacetylase, Methylation
3 Jul 2018
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Part 1
What is strong inference and the advantages?
• Strong inference is that experimental approach whereby you develop a hypothesis, test the
hypothesis, reject or accept the hypothesis, and formulate other hypotheses to test based
on the ones you have rejected or accepted.
• It is advantageous in eliminating bias and erratic behaviour.
• They are specific.
• Provides structured experimental approach which allows you to determine the facts at a
faster rate.
• Forms firm inductive conclusions and outlines the possibility of several possible
explanations.
What are the sources of phenotypic variation?
• Individual: where individual differences are acted upon by natural selection.
• Population: population variance = genetic effects + environmental effects + interaction
between genetic and environmental effects + error.
• Phenotypic plasticity: environmentally sensitive productions of alternate phenotypes by a
given genotype. The genotype is able to express alternative phenotypes when exposed to a
particular environment. Can observe this phenomena by the reaction norm.
What is the principle of allocation?
• When energy is allocated to the performance of one function, this limits the amount of
energy available to other processes.
How would individual plasticity influence selection?
• It would weaken selection as the organism can change their phenotype to better withstand
the environmental pressures. Thus, limiting natural selections pressure on the individual.
Explain why variable environments favour the performance of generalists?
• Generalists have a much wider curve, as they are able to maintain functioning at extreme
environmental conditions.
• Specialists perform better than generalists at optimum environmental conditions, however
they are not able to maintain functioning at extreme environmental conditions.
• Specialists have a large change in functioning, with small changes in environmental
conditions.
• Generalists have small changes in functioning, with small changes in environmental
conditions.
Explain frequentist statistics:
• Statistics that determine how frequently a result like this would be observed.
• Calculates false discovery rates using confidence intervals, effect size and power analysis.
Explain Bayesian logic:
• Uses experimental data to update prior knowledge.
• Doesn’t assume underlying distributions, thus it is particularly useful for small sample sizes.
• If the likelihood of two people having the same fingerprints is, say, one in 500,000, and
fingerprints matching person X are found on the murder weapon, then surely it is a near-
certainty that X is the murderer? And if I tell you that 99.5% of people with a confirmed HIV
infection test positive for HIV, then surely a person who tests positive is 99.5% likely to have
the virus? In fact, both of these conclusions of wrong. Dead wrong, if you'll pardon the
expression. The importance of Bayes' theorem is that it will tell you the true likelihood of a
person having an HIV infection if he tests positive, and the true likelihood of person X being
the murderer if his fingerprints turn up on the weapon.
• With a large sample size this begins to give you frequentist statistical conclusions.
What does the P-value signify?
• It is a probability statement, that the difference in means is at least as large as that
generated from a random sample if the treatment does not have an effect.
• You should combine frequentist statistics to this probability statement.
Adaptation:
• Heritable changes in phenotype that result from natural selection or genetic drift. This
increases the individuals fitness to a particular environment.
• Selection: different selection pressures of different environments.
• Genetic drift: decreased gene transfer, thus speciation occurs.
• It can be stabilizing or directional.
What are the problems with two species comparisons?
• Species are inherently different, thus differences in environmental response could be
confounded with speciation differences.
• In order to make a valid correlation, there needs to be at least three independent data
points as the degrees of freedom is N-2.
• Instead you should use the same species in isolated environments and compare them to see
adaptation.
Why is phylogenetic relatedness important for multispecies comparisons?
• As all species originate from a common ancestor.
Document Summary
The genotype is able to express alternative phenotypes when exposed to a particular environment. Can observe this phenomena by the reaction norm. What is the principle of allocation: when energy is allocated to the performance of one function, this limits the amount of energy available to other processes. It would weaken selection as the organism can change their phenotype to better withstand the environmental pressures. Thus, limiting natural selections pressure on the individual. Explain frequentist statistics: statistics that determine how frequently a result like this would be observed, calculates false discovery rates using confidence intervals, effect size and power analysis. Explain bayesian logic: uses experimental data to update prior knowledge, does(cid:374)"t assu(cid:373)e u(cid:374)derlyi(cid:374)g distri(cid:271)utio(cid:374)s, thus it is parti(cid:272)ularly useful for s(cid:373)all sa(cid:373)ple sizes. In fact, both of these conclusions of wrong. Adaptation: heritable changes in phenotype that result from natural selection or genetic drift.
