What is directional selection, and how does it change a population over time?
Genotypes toward one extreme are the most genetically fit. Genotypes toward one extreme survive the best.
What major selective pressure acts on the males of many species?
Why are females of many species choosy about mates?
In many species, males only contribute to their offspring with their DNA so females want to mate with males that have superior alleles in their genes.
Why do female birds often choose males that are brightly colored, and have long tails?
These males signify health, agility, strength, and cleverness.
Explain how directional selection can lead to pesticide resistance in insects, and drug resistance in bacteria and viruses.
Insects possessing a mutation resistant to pesticides will survive and reproduce while the rest of the population will die. Lucky ones will also survive if they managed to avoid the pesticide sprays. Populations of bacteria and viruses are becoming resistant to pesticides and drugs as a result of mutations.
Do individual insects or germs develop resistance?
Do useful mutations occur because they are useful to an organism?
change in the genotypes of a population over time. Changes can include the addition of new genotypes, the loss of old ones, or a change in the frequencies of different genotypes.
a group of individuals of the same species living in the same location
greater survival and reproduction of individuals with certain genotypes over others in a population, due to the selective pressures of the local environment. As a result of natural selection, genetically fit genotypes become more common in the population over time, while genetically unfit genotypes become less common in the population over time.
a component of an environment that determines who survives there and who doesn’t. Selective pressures vary among different environments. Individuals that are genetically fit will survive the selective pressures of a particular environment, while individuals that are genetically unfit will not survive.
having a genetic makeup that enables survival and reproduction in a particular environment
natural selection in which intermediate genotypes are most genetically fit
natural selection in which genotypes toward one extreme are the are most genetically fit
the name given to the process of natural selection when humans are a very strong, purposeful selective pressure on a population. Because the selective pressure of humans is so strong, artificial selection can produce significant genetic changes in populations more quickly than natural selection. This process has created all breeds of domestic animals and plants from wild ancestors.
the scientific name for wild lettuce. Over thousands of years, artificial selection has resulted in the development of many crop breeds that are genetically distinct from each other. Examples include cabbage, Brussels sprouts, kohlrabi, kale, broccoli, and cauliflower.
the scientific name for the domestic dog. Over thousands of years, artificial selection has resulted in the development of all domestic breeds of dog from one ancestor: the wolf.
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