Ch 8 Review Flashcards
Explain what variation within a species means.
Explain how variations can arise in a sexually
reproducing species
- naturally occurring genetic differences among individuals of the same species
sexual reproduction (mutations is for asexual r)
-most of the variation is due to the scrambling
of existing alleles, including those that originated as mutations in earlier generations
-the processes of meiosis and fertilization shuffle the alleles and recombine them
-each offspring receives a new combination of alleles
Explain what “allele frequency” means and
provide an example
Allele frequency refers to how common an allele is in a population
-e.g. in a pop. there are 14 red flower alleles and 6 white flower alleles, so the allele frequency for red is 70% (14/20) and for white is 30% (6/20)
What is macroevolution? Give an example.
macroevolution encompasses more dramatic biological changes, many of which are evident in the fossil record
-these changes include the origin of different
species, the extinction of species, and the evolution of major new features of living things, such as wings or flowers
-e.g. humans, tetrapods, birds
-birds- through fossil records, scientists have long
believed that birds evolved from the theropod
dinosaur Archaeopteryx. It took tens of millions
of years for the exceedingly large theropods to
evolve into the much smaller, hollow-boned,
lightweight, feathered birds of today that can fly
long distances.
What genotype for sickle cell disease is the
most beneficial for individuals living in regions
where malaria is common? Why?
heterozygous individuals with sickle cell disease are the most beneficial because Individuals with just one copy of the sickle-cell allele are resistant to the disease malaria
The Hardy-Weinberg equilibrium applies only if five specific conditions of the population are met. Which of the following does not represent one of those conditions?
a) There must be no movement of individuals in or out of the population
b) There must be random mating
c) There must be no natural selection taking place
d) The population must be contained and small
The population must be contained and small
-The Hardy-Weinberg equilibrium includes no movement of individuals in or out of the population, random mating, no natural selection, no mutations, and a large population
In the 1940s farmers in North America lost approximately 7% of their crops to pests. During the last decade, however, the percentage of crop loss has increased to nearly 13%, despite much more widespread pesticide use.
This example best describes
a) directional selection.
b) sexual selection.
c) the bottleneck effect.
d) genetic drift.
directional selection.
Directional selection occurs when individuals at one end of the phenotype range have a higher fitness. Pests that survive pesticide applications survive to reproduce and pass along their traits to their offspring. After several generations, directional selection has resulted in pests with a higher fitness.
These wild horses show a range of different coat colours even though they belong to a single population.
These differences in coat colour largely result from:
-natural selection.
-sexual recombination.
-exposure to environmental chemicals.
-DNA replication errors.
sexual recombination.
-In organisms that reproduce sexually, the most important source of variation is sexual recombination of existing alleles during the production of gametes.
This is a golden hamster, a popular pet. All golden hamsters alive today descended from a single mother and her litter of pups collected from the wild in Syria in 1930.
This best describes which kind of microevolution?
bottleneck effect
At some point in their lives, female Hamadryas baboons, the individual on the left in this photo, leave their birth group and migrate to a different one. This behaviour helps to maintain the fitness of the species because it helps to preserve the species’ genetic diversity. This is an example of which kind of microevolution?
-Genetic drift
-The founder effect
-Sexual selection
-Gene flow
gene flow
As polar bear habitat shrinks, polar bears will likely come into contact with other bear species such as the Kodiak brown bear in Alaska. There are confirmed examples of these two species reproducing with each other to create fertile offspring. These hybrid bears may become more common as a result of global warming. Which type of evolution is this?
-Convergent
-Habitat isolation
-None of the available choices describes this
type of evolution -Hybrid inviability
Correct Answer: None of the available choices describes this type of evolution
-Convergent evolution occurs when distantly-related species in different locations develop similar adaptations.
-Habitat isolation occurs when two groups do not interbreed based on a geographic isolation between the groups.
-Hybrid inviability occurs when different species reproduce, but the offspring are not healthy enough to reproduce themselves.
None of these terms describes the bear species in this question.
Which statement about punctuated equilibrium is true?
a) Punctuated equilibrium is a theory that claims all major evolutionary changes occur only after catastrophic widespread extinction events remove potential competitors
b) Punctuated equilibrium is a theory that claims evolution can occur through rare rapid events of speciation
c) Punctuated equilibrium is a theory that claims once a certain amount of genetic variability accumulates in a species, that species must branch off into new species
d) Punctuated equilibrium is a theory that claims evolution of all species results from sudden short-lived violent environmental stress
Correct Answer: Punctuated equilibrium is a theory that claims evolution can occur through rare rapid events of speciation
-Gradualism, or the slow, gradual change in a species eventually bringing about speciation is not the only way new species can appear.
-Sudden, relatively quick evolutionary changes may also result in speciation. This is called punctuated equilibrium.
The marine iguana is believed to have evolved from a land iguana, which arrived on the islands from South America perhaps on driftwood.
There is a species of land iguana with which the marine iguana will mate. The offspring can climb cacti like the land species and it can also forage for algae so they are a genetic success except that they are sterile.
Which kind of reproductive barrier between marine and land iguanas is this?
-Post-reproductive hybrid infertility
-Post-reproductive hybrid inviability
-Behavioural isolation
-Mechanical isolation
Correct Answer: Post-reproductive hybrid infertility
Although the two species can mate successfully, their offspring are infertile, and cannot reproduce themselves. This condition is called post-reproductive hybrid infertility.
A seed-eating bird colonizes one island in a chain of islands (bottom bird in diagram below). Over many generations the seed eating bird colonizes five other nearby islands and each group evolves independently to exploit that island’s food resource.
Which descriptions fit this model of evolution?
I) Adaptive radiation
II) Convergent evolution
III) Divergent evolution
IV) Speciation
I, III and IV
Adaptive radiation, Divergent evolution and Speciation
The Kagu is indigenous to a group of islands near Australia. It is almost flightless and it builds ground nests of sticks.
Why are there so many island species of birds such as the Kagu flightless?
There are no predators on many islands
What is not an example of co-evolution?
a)The evolution of the hoverfly to look like a wasp so it can avoid being eaten
b)The evolution of the monarch caterpillar, which incorporates a plant toxin from its food to make itself poisonous
c)The evolution of poison and brightly coloured skin in the poison-arrow frog
d)The evolution of flowering plants and insects that pollinate them
Correct Answer: The evolution of poison and brightly coloured skin in the poison-arrow frog
Some species have life cycles interwoven so closely with other species that they may co-evolve. This refers to changes in one species causing changes in another. All of the examples given here illustrate co-evolution except the poison arrow frog, whose bright colours serve as a reminder to predators of the poisons found in members of the species.
Over 65 million years ago, albatross-like penguin ancestors began losing the ability to fly and gaining the ability to swim and dive. Compare the morphology of the albatross with that of a penguin, shown here.
This transition took about 20 million years according to fossil records. Through what process did penguins evolve?
-Convergent evolution
-Mimicry
-Natural selection
-Co-evolution
Correct Answer: Natural selection
Albatross-like penguin ancestors underwent the process of natural selection to evolve into the flightless, diving penguins of modern times.