Chapter 14: Natural Selection & Adaptation

An organism's fitness depends on its __________.

*a. ability to survive and reproduce* b. population c. ability to mutate d. physical size e. ability to swap genetic material with other organisms

The process by which populations become better suited to their environment as a result of natural selection

Adaptation ; page 310

Chemicals that either Kill bacteria or Slow their Growth by interfering with the function of essential bacterial cell structures

Antibiotics ; page 307

Mutation is not the only way populations of bacteria can acquire new genetic variation because...

Bacteria can acquire new alleles - even new genes - through a mechanism called Gene Transfer (pieces of DNA pass from one type of bacteria to another); page 308

Bacteria accumulate mutations at a relatively high rate because...

Bacteria reproduce much more rapidly than any other organism, and each time their DNA is replicated, there is a chance that genetic mutations will occur (and then be carried into each daughter cell) ; page 308

Most commonly prescribed class of antibiotics, including penicilin and cephalosporin antibiotics, that work by interfering with a bacteria's ability to synthesize cell walls

Beta-lactams ; page 307

A type of asexual reproduction in which one parental cell divides in two; the bacteria replicates its single chromosome, grows in size, and then splits into two daughter cells (each with a copy of the parental DNA.

Binary Fission ; page 308

Some bacteria produce enzymes called beta-lactamases that

Chew up beta-lactam antibiotics ; page 309

Genetic changes ultimately alter staph bacteria proteins in ways that help staph dodge antibiotic drugs by...

Coding for proteins that can disable antibiotics or code for proteins with altered shapes to which the antibiotic can no longer bind; page 309

Interplay between phenotype and environment

Determine frequency of traits in a population ; PowerPoint

A type of natural selection in which organisms with phenotypes at one end of a spectrum are favored by the environment

Directional selection ; page 311

Three major patterns of natural selection

Directional selection, stabilizing selection, & diversifying selection ; page 311-312

A type of natural selection in which organisms with phenotypes at both extremes of the phenotypic range are favored by the environment

Diversifying selection ; page 311

Bacteria that can survive antibiotics

Drug-resistant bacteria ; page 307

A change in the frequency of alleles in the population over time

Evolution ; page 310

An organism's ability to survive and reproduce in a particular environment

Fitness ; page 310

Alleles that confer resistance to antibiotics

Increase an organism's fitness ; PowerPoint

The process of differential survival and reproduction of individuals within a population in response to environmental pressure that leads to change in allele frequencies in a population over time

Natural Selection ; page 310

Stabilizing selection occurs when

Phentoypes at each end of the spectrum are less suited to the environment than organisms in the middle of the phenotypic range ; PowerPoint

A group of individuals of the same species living together in the same geographic (relative) area

Population ; page 309

A type of natural selection in which organisms near the middle of the phenotypic range of variation are favored by the environment

Stabilizing selection ; page 311

When a population's environment favors some traits over others,

The frequencies of the alleles that code for those traits in the population change over time; page 309

The higher an organism's fitness is

The more increased the likelihood of alleles being passed on to the next generation ; PowerPoint

If traits improve fitness

Traits become more common in population ; powerPoint

Directional selection occurs

When a single phenotype predominates in a particular environment ; PowerPoint

Which of the following is not a pattern of natural selection?

a. diversifying selection b. stabilizing selection c. directional selection *d. All of the above are patterns of natural selection.* e. None of the above is correct.

Which of the following factors is not going to affect how natural selection acts on a given group of organisms?

a. survival rate of individuals b. reproductive success of individuals c. which phenotypes are present d. both a and b are correct *e. All of the above are correct.*

Diversifying selection typically occurs in a "patchy" environment, in which

extremes of the phenotypic range do better than middle range individuals ; PowerPoint