EVOLUTION
EVOLUTION OF A POPULATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Mutations can act as a molecular clock that shows when species had a common ancestor.
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Changes in gene sequences generally occur when two species interbreed.
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Changes in gene sequences generally occur when one species evolves into another species.
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Although some mutations have little effect, many mutations act to distinguish one species from another.
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Detailed explanation-1: -Homologous structures provide evidence for common ancestry, while analogous structures show that similar selective pressures can produce similar adaptations (beneficial features). Similarities and differences among biological molecules (e.g., in the DNA sequence of genes) can be used to determine species’ relatedness.
Detailed explanation-2: -These shared genes are evidence of evolution from a common ancestor and the relatedness of all life on Earth. The shared genes are called homologous genes, or genes which share a common ancestry either between or within species.
Detailed explanation-3: -A balanced polymorphism is a situation in which balancing selection within a population is able to maintain stable frequencies of two or more phenotypic forms. Evidence for balancing selection can be found by increased levels of genetic variation between alleles or haplotypes in a species.
Detailed explanation-4: -Another scientist, Thomas Hunt Morgan, conducted studies in which he induced genetic mutations in populations of the fruit fly, Drosophila melanogaster (Figure 4.5). His work demonstrated that most mutations merely increased variation within populations, rather than creating new species (Morgan 1911).