Evolution by Natural Selection- Chapter 22

What did Charles Darwin and Alfred Wallace claim?

that species have changed through time and that natural selection explains the pattern of evolution

What did Plato claim?

every organism was an example that was created by god and they remained unchanged

What is typological thinking?

the idea that species dont change and that variation in species is unimportant

What is and who claimed the great chain of being?

Aristotle- species were organized into a fixed sequence based on increasing size and complexity

What are the two steps of the great chain of being

1. species are fixed types

2. some species are higher or “better” (hiearcy)

What did Jean-Baptise de Lamark prepose?

simple organisms originate at the base of the great chain of being by spontaneous generation and then evolve by moving up the chain

What is the inheritance of aquired characters?

Individuals change in response to their environment and then pass on those changes to their offspring

Who created the theory of evolution by natural selection?

Darwin and Wallace

What are the 3 claims of the theory of evolution by natural selection?

1. overturned that species are static and unchanging

2. replaced typological thinking with population thinking

3. it was scientific- could be tested through observation and experimentation

How did Darwin describe evolution?

a descend with modification- change over time produced modern, modified species, and species are related by common ancestry

What are fossils?

traces of organisms that lived in the past (fossil record)

indisputable evidence of change through time and evidence for extinct species

What are transitional forms?

fossils with traits that are intermediate between earlier and later species

When do intermediate forms occur?

if traits observed in more recent species evolved from traits in more ancient species

What are vestigial traits

physical characteristics or structures within an organism that have lost most or all of their original function over time through evolution

Examples of evolutionary changes?

Bacteria have evolved resistance to drugs

insects have evolved resistance to pesticides

What are homologies?

similarity that exists in species descended from a common ancestor

What are the three interactive levels of homologies

structural, genetic, and developmental

What is structural homology

similarity in adult morphology ex. common structural plan in limb bones

Genetic homology

similarity in DNA sequences ex. identical in amino acid sequence

developmental morphology

similarities in embryos of different species ex. chickens, humans, and cats have gill pouches and tails

Evolution of cetaceans

whales evolved from terrestrial ancestor

phylogey of fossil cetaceans indicate gradual transition between terrestrial and aquatic

mammals, warm blood, swim up and down

molecular comparison show hippos are the closest to whales

vistigial limbs as adults or embryos

What are Darwins four postulates?

1. individuals in population vary in traits (different alleles)

2. some differences are heritable

3. in each generation, more offspring are produced that can survive

4. individuals w/ certain heritable traits are more likely to survive and reproduce.

What happens when you change the genetic characteristics of a population over time?

it will change the genotipic and phenotypic characteristics

When does evolution by natural selection occur?

When certain traits within an organism provide an advantage for survival and reproduction

theory of evolution in TB

DNA from rifamoin-resistant bacteria had a single point mutation

during antibiotics cells w/ normal RNA polymerase grow more slowly or die, while those w/ mutant RNA polymerase profilierate

variation in phenotypes of the two strains was due to variation in genotypes

caused variation in reproductive stress

what contrasts Lamarks hypothesis?

individuals do not change when they are selected, they simple produce more surviving offspring than others

natural selection just sorts existing variants, it doesnt change them

acclimation

when indiv. phenotype changes in response to changes in the environment, but genotype remains fixed so the changes are not passed on to offspring

adaptation

the allele frequencies in a population change in response to natural selection

do not occur bc organisms want or need them

What does it mean that evolution is not progressive?

that it does not produce better or more complex organisms

vestigal traits confer no known benefit

true

How are adaptations constrained

genetics, fitness, trade-offs, and historical

genetic correlation

when selection favoring alleles for one trait causes a correlated but suboptimal change in allele for another trait

occur bc/ of pleiotropy- a single gene affecting multiple traits

fitness trade-off

when an organism gains an advantage but at the cost of a disadvantage in another

history constraint

traits evolve from previously existing traits, adaptations are constrained by history