Chapter 3 Flashcards
Evolution by Natural Selection
What was Darwin’s conclusion in On the Origin of Species b Means of Natural Selection?
Earth’s organisms were not independently created, but are instead descended with modification form a single common ancestor or a few
What is the process that yields the pattern e call evolution?
Natural selection
What was the final act that led to a greater acceptance of natural selection?
The rediscovery of Mendel’s ideas in 1900 and other three decades of work on population genetics
Darwin’s postulates on natural selection:
- The individuals within a population differ from one another
- The differences are, at least in part, passed from parents to offspring
- Some individuals are more successful at surviving and reproducing than others
- The successful individuals are not merely lucky; instead, they succeed because of the variant traits they have inherited and will pass to their offspring
If all of Darwin’s postulates hold, what happens?
The composition of the population inevitably changes from one generation to the next
Darwinian fitness:
An individual’s ability to survive and reproduce
Adaptation:
A trait that increases an organism’s fitness relative to individual’s lacking it
Heritability:
The fraction of the variation in a population that is due to differences in genes
Which of the following is a true statement regarding pre adaptations?
A trait that evolved for one function, but that coincidentally is also suited for a new, different function
Which of the following statement is central to the idea of uniformitarianism?
Natural laws that are observable today also operated in the past. Geological change happens gradually for the most part
Successful artificial selection, such as that practiced by plant and animal breeders to modify their crops and livestock, depends on which of the following?
Breeders must be able to selectively breed the individuals with the most desirable traits. Some individuals must have more desirable traits than others. When individuals with the most desirable traits are bred, their traits must be passed from parent to offspring.
Which is the best definition of Darwinian fitness?
The ability of an individual to survive and reproduce in a certain environment, compared to other individuals
Exaptation:
A trait that is used in a novel way. They represent coincidence. It enhances an individual’s fitness fortuitously. A trait that is elaborated into a completely new structure by selection related to its new function.
Secondary adaptations
Additional modifications that arise during exaptation.
Blending inheritance:
Favorable variants would merge into existing traits and be lost. Biologist thought inheritance worked like pigments in paint. Instead, alleles are passed on intact to offspring, thus making inheritance particulate (not blending).
What are angiosperms?
Monocots + Dicots
Testing postulate 3: Do individuals vary in their success at surviving and reproducing?
In every natural population studied, more offspring are produced each generation that survive to breed.
Testing postulate 4: Are survival and reproduction nonrandom?
Individuals who survive and go on to reproduce, or who reproduce the most, are those with certain variations.
In the case of the Galapagos finches, seeds ranged from small and soft to large and hard, as the soft and small seeds were the first to be eaten, only large and hard seeds were left after the drought, large birds with deep, narrow beaks were more successful at cracking the seeds left and therefore more successful at surviving and reproducing.
Testing Darwin’s prediction: Did the population evolve?
Because of the drought, the finch population evolved. Selection occurs within generations; evolution occurs between generations
The nature of natural selection
Natural selection acts on individuals, but its consequences occur in populations
Natural selection acts on phenotypes, but evolution consists of changes in allele frequencies.
Natural selection is not forward looking; evolving populations always lag at least a generation behind changes in the environment.
Although selection acts on existing traits, new traits can evolve via mutations and genetic recombination.
Natural selection does not lead to perfection.
It is nonrandom, but it is not progressive.
Natural selection is nonrandom, but is not progressive
The automatic sorting among variant phenotypes and genotypes to increase survival and reproduction of some variants over other is non random. However, it is not progressive in the sense of moving toward a predetermined goal.
There is no such thing as a higher or lower plant or animal.
Selection acts on individuals, not for the good of the species
Individuals do not do things for the good of their species. They behave in a way that maximizes their genetic contribution to future generations.
Modern synthesis of Darwin’s postulates
- Individuals vary as a result of mutation creating new alleles, and segregation and independent assortment shuffling alleles into new combinations.
- Individuals pass their alleles on to their offspring intact.
- In every generation, some individuals are more successful at surviving and reproducing than others.
- The individuals most successful at surviving and reproducing are those with the alleles and allelic combinations that best adapt them to their environment.
The argument from intelligent design/creationism
Contends that adaptation- traits that increase the fitness of individuals that possess them- must result from the actions of a conscious entity
