Patterns/Mechanisms of Evolution Flashcards
Populations
groups of individuals that are of the same species
Fitness
an organism ability to survive and reproduce
Adaptation
trait that increases fitness
Mutations
random changes in DNA; seldom increases fitness
Natural Selection
the difference in reproduction of genes in a population because of the traits that those genes make
Evolution
the change of a populations genetic composition over time
Gene Pool
all the alleles of a gene in a population
What are the five major mechanisms of evolution?
natural selection, mutation, genetic drift, non-random mating, and gene flow
Natural selection is….
function driven and non-random reproduction of traits
Genetic Drift
the result of random fluctuations in the allele frequency of a population; can greatly affect small populations; this can be due to bottleneck affect (a disaster happening and randomly taking out individuals) or just fluctuations from generation to generation
Nonrandom Mating
when mates are chosen by a specific phenotype or characteristic
Gene Flow
refers to the emigration and immigration of individuals between populations; basically migration
Requirements for HWE
no natural selection, no mutations, no gene flow, no genetic drift (infinitely large population), and only random mating
p
the allele frequency of the dominant allele
q
allele frequency of the recessive allele
p^2
frequency of homozygous dominant individuals
2pq
frequency of heterozygous individuals
q^2
frequency of homozygous recessive individuals
What are the two equations for HWE?
p+q=1 and p^2 + 2pq + q^2=1
What is the equation for the chi-squared formula?
x^2 = summation of [(observed - expected)^2 / expected]
How to find of degrees of freedom?
subtract one from the number of phenotypes or n-1
What number is looked at on a Chi-Squared distribution table?
0.05
What does 0.05 mean for Chi-Squared?
the chance that our results are due to random chance are less that 5%
What does it mean if the chi-squared value is above the critical value?
the observed is statistically significantly different from the theoretically expected; the population is not in HWE; if chi-squared is bigger than the critical value, something is causing the difference. it is not from random chance
What does a large p-value mean?
tells you your datasets are not very different; strong evidence of the null hypothesis being true
What does a small p-value mean?
tells you your datasets are different and there is statistical significance; you have evidence to say there is something causing the difference and it is not random; the smaller the p-value the stronger evidence that you should reject the null hypothesis
What does a p-value under 0.05 or 5% mean?
potentially good enough to be taken seriously in some way as difference between your datasets
What is a t-test?
a statistical test used to compare the means of two groups of data
What are p-values?
the probability that you would get your results if your datasets werent actually different; probability that your null hypothesis is true
