introduction to the theory of evolution and natural selection

biological evolution

change in allele frequencies over time; change in the genetic composition of a population over time; change in inherited traits from generation to generation; happening all the time, natural state of a population

(1) there is variation for a trait among individuals, (2) some of the variation for a trait is heritable, (3) there is differential reproductive success among individuals, (4) there is a consistent relationship between the trait and reproductive success

what are the requirements for natural selection?

natural selection

increase in the frequency of individuals w traits that confer a relative increase in reproductive success within a population

normal curve

frequency distribution in which most of the observations live at an intermediate value and progressively fewer observations live at extremely low and high values

frequency distribution

a metric showing how often all possible trait values occur in a population

measures of central tendency

metrics that define where most of the observations occur (the center) within a dataset or population; mean, median, mode

measures of dispersion

metrics that define how much the overall data deviates from the center - how much variation there is; variance, standard deviation, standard error

biological population

every individual of a particular population in a particular place

statistical population

a group about which you would like to make a statistical inference

median

the center-most observation in a list of observations, if the list of observation is event, compute the average of the two center-most observations

mean

a number representing the statistical center of a list of observations, or the number representing the most common value in the set

mode

the observation that occurs at the highest frequency

variance (s^2)

a value representing the amount by which each observation in a list of observation deviates (or differs) from the calculated mean value

standard deviation (s)

a value representing how spread out the observations are in a given dataset relative to the mean

standard error

a value representing the standard deviation across a specific number of values

95% confidence interval

a range of values indicating a 95% probability of containing the true mean of a population/list of observations

interquartile range

a range of values indicating where approximately 50% of the observations lie in a given list of observations (the observations in the middle of the list of observations)

10-90 percentile

the range below which 10-90% of the observations in a given dataset lie