-the contribution an individual makes to the gene pool of the next generation, relative to the
contributions of other individuals
-selection acts more directly on phenotype than genotype
-occurs when conditions favor
-gene variability tends to be greater than nucleotide variability (a single change in nucleotides
can cause great gene variability)
-Geographic variation, differences in the genetic composition of separate populations (because
of their environment)
Intersexual Selection (Mate Choice)
-individuals of one sex (usually females) are choosy in selecting their mates from the other sex,
usually depending on the showiness of the males appearance or behavior.
-Such showiness may pose some risk of predation b
-used to determine whether evolution is occurring in a population by comparing to a hypothetical
-a population is a group of individuals of the same species that live in the same area and
-change events can also cause allele frequencies to fluctuate unpredictably from one generation
to the next, esp. in small populations
The Founder Effect
-when a few individuals become isolated from a larger population, this smaller group ma
-Bacteria genome consists of double-stranded, circular DNA molecule with a small amount of
protein while eukaryotic chromosome consists of one linear DNA molecule associated with a
large amount of protein)
-bacterial DNA coils into the nucleoid that is no
-in prokaryotes, bacterial chromosome is circular and has a single origin of replication, short
stretch of DNA having a specific sequence of nucleotides.
-a replication bubble is opened. Multiple replication bubbles form and eventually fus
DNA Replication Complex
-primase acts as a molecular brake, slowing progress of the replication fork and coordinating the
rate of replication on the leading and lagging strands.
-DNA moves through the complex during the replication process.
Why Natural Selection Cannot Fashion Perfect Organisms
-selection can only act on existing variations
-evolution is limited by historical constraints
-adaptations are often compromises
-chance, natural selection and the environment interact.