Fill in Each of the Blanks with the Best Word

Short Answer

Fill in each of the blanks with the best word or phrase selected from the list below. Not all words or phrases will be used; each word or phrase should be used only once.
Genetic variation arises from random ____________-changes in DNA that insert, delete, or substitute one or more base pairs, resulting in a new ____________ (version of the gene). If this change results in a phenotype that gives the organism a reproductive advantage, the new allele is likely to ____________ in frequency in the population. The ____________ of an allele can be defined as the ratio of offspring (or grandchildren) produced by individuals of a certain genotype over the highest number produced by any genotype in the population. ____________ selection increases the frequency of alleles with higher fitness. In a ____________ population, allele frequency can also change over generations due to sampling error (because not all individuals produce the same number of offspring). This change in allele frequency by chance is called genetic ____________ and could in principle even lead to the ____________ (frequency of 1) of an allele with relatively low fitness.
allele large
decrease mutation
drift negative
fitness positive
fixation shift
increase small
Evolution of Neuronal Communication