- proteins
- the sequence of amino
acids making up the protein.
- four different types
of nucleotides (A, T, C, and G)
- an amino acid
- a specific section of
DNA, from a start codon to a stop codon and everything between, that is the
code for producing a protein.
- One of the alternative
forms of a gene.
- All of the alleles (types
and proportions) of all the genes in a population.
- Genetic change in a
population (or change in a population's gene pool).
- Mechanisms of evolution
- Mutation: random
change in the nucleotide sequence in DNA due to copying errors or the
effects of chemicals/radiation. Mutation is the ultimate source of new
alleles and genes.
- Migration (Gene Flow):
the movement of alleles between populations as a result of movement of
individuals from one population to another.
- Chance (Genetic Drift):
a change in allele frequencies in a population due to chance (differences
in reproductive success not due to genetic makeup of individuals like
in natural selection). Genetic drift does not lead to adaptation, and
its effects are stronger on smaller populations.
- Natural Selection:
change in allele frequencies in a population due to differential reproductive
success among the members of the population. This is the only mechanism
that leads to adaptive changes in the population's gene pool.
- Natural Selection Flow
Chart:
- Mutation and Recombination
produces Genetic Variability in a population
- Environmental Selection
Pressures act on the population creating...
- Differential Survival
and Differential Reproduction which leads back to...
- Mutation and Recombination
to create a potentially changed gene pool.
- Genetic traits that
increase an individual's reproductive success in that environment compared
to individuals without the trait.
- Environmental factors
that affect differential survival and/or differential reproductive success
among members of a population. The long ears of jackrabbits were likely selected for by hot temperatures; those jackrabbits with longer ears were better able to radiate off heat to keep their bodies cooler and so outsurvived jackrabbits with shorter ears.
- Fitness is the relative
ability of an individual to produce grandchildren compared to other individuals
in the popupulation. So "survival of the fittest" means alleles
in the most reproductively successful individuals survive better into the
next generation than alleles in less reproductively successful individuals.
- Types of evolution
- Divergent Evolution:
different populations within a species become genetically different due
to experiencing different selection pressures. Example: White-tailed deer
tend to be larger in the north than in the south.
- Convergent Evolution:
different species come to look/behave similarly due to experiencing similar
selection pressures. Example: sharks (fish) and dolphins (mammals) look
similar.
- Coevolution: interacting
species act as selection pressures on each other due to their interactions.
Example: as prey get faster, predators tend to get faster.
- Speciation occurs through
divergent evolution when the genetic differences between the populations become
great enough to prevent the two populations from being able to reproduce successfully.
|