Lecture 4: Natural Selection and Adaptation Flashcards
Adaptation (noun)
Features that enhance survival and reproduction
Natural selection is not goal oriented, ________
it just happens
How have cacti adapted to prevent water loss? (3 ways)
1) lack leaves
2) thicker stems
3) hairs that reflect light and reduce body temperature
What do soapberry bugs do?
They pierce the seed pod of soapberry plants to feed on the seeds
Where have soapberry plants been introduced?
Texas and Florida
Florida’s introduced soapberry plants are ____ than the native plants
smaller
Texas’s introduced soapberry plants are ____ than the native plants
larger
What are the results of soapberry plant introduction?
In Texas, soapberry bugs have evolved longer beaks. In Florida, soapberry bugs have evolved shorter beaks.
Why has DDT resistance increased?
there is a cumulative number of arthropod pests evolving resistance to DDT over time as DDT use has increased over time
What is cryptic coloration?
An adaptation where organisms blend in with their surroundings to avoid predators
Explain background matching in Lice
Two species of lice live in the Purple-throated fruitcrow. One of them has a more rounded body and lives on the head and neck where the bird cannot see it. The other lives on the body where the host can see it and preen it off. The body lice is darker and matches the color of the fruitcrow.
Explain lice background matching in pigeons
Light colored lice live on the Australian pied imperial pigeon. Dark colored lice live on the Rock pigeon.
Host preening
Birds using their beaks to position their feathers and remove lice
Vestigial feature
Features that are not used.
Ex: remnants of eyes in cave
fish
Which two people introduced the word “exaptation?”
Stephen Jay Gould and Elizabeth Vrba
What is exaptation
A trait that has evolved for one purpose but is now used for another purpose
Why did feathers evolve?
They weren’t used simply for flight
What is an important example of an intermediate fossil that we learned about?
Archaeopteryx
Analysis of Archaeopteryx revealed that …
Feathers evolved for display, not flight
What is differential reproduction success?
Individuals leave more offspring in the next generation than do others often due to traits that create advantages in survival and reproduction
What are heritable phenotypes?
Phenotypes that can be inherited, “each phenotype has a genotype”
Adaptedness
the ability to survive and reproduce in a given environment; the cumulative product of natural selection
Adaptation (verb)
The process through which adaptedness is acquired
Fitness
relative measure of reproductive success of individuals
Sexual selection involves which two factors that influence reproductive success?
competition for mates (male/male competition)
mate choice (female choice for traits in males)
Neutral allele
Do not alter fitness
How do the frequency of neutral alleles change?
Via genetic drift
What are the two types of mutation?
Synonymous and nonsynonymous
What is a synonymous mutation?
the amino acid doesn’t change
What is a nonsynonymous mutation?
the amino acid changes
Genic selection
Natural selection acting at the level of the gene
Transposable elements (transposons)
Self-replicating DNA sequences
Who discovered transposons?
Barbara McClintock
Evidence suggests that transposons cause what?
A majority of mutations
Who created the concept of group selection?
Wynne-Edwards
What is group selection?
Natural selection acts at the level of the group, not at the level of the individual
How does group selection explain the purpose of territories?
the population as a whole benefited from the rationing effects of territoriality
Who disagreed with group selection theory?
George Williams
Altruism
individuals might do things for the good of the group
George Williams argued that what type of selection occurs?
Individual selection
What did George Williams say about selfish genotypes?
The selfish genotype becomes fixed, even if it increases the chance of population extinction
What illustrates the problem of cheaters and altruism?
Lemming Myth: populations of lemmings in the arctic throw themselves into the sea for the good of the group. All it takes is one cheater that doesn’t do this, and the cheaters prevail
Why did JBS Haldane say “I would save two brothers or eight cousins?”
Siblings share 50% of genes
Cousins share 25% of genes
Inclusive fitness is a measure of …
The relative number of an individual’s alleles that are passed onto future generations
What are the two components of inclusive fitness?
Direct and indirect
What is direct fitness?
the result of individuals own reproductive success
What is indirect fitness?
when the individual helps relatives
What is kin selection due to?
selection acting indirectly to help relatives
Microevolution
result of natural selection on individual species
Macroevolution
evolution at the group level instead of the individual species level
How has adaptation led to changes in the mollusk eye?
Adaptations have resulted in complexity in the eyes of mollusks
What is an example of available variation?
The panda having a “false” thumb
Historical constraint
since evolution does not “design” organisms from scratch, each step is contingent on preceding steps
Pleiotropy
a gene can have more than one effect
What was the result of the Galapagos finches study?
Finches with different sized bills adapted to eating different size seeds
