Explain why genetic variation within a
population is a prerequisite for evolution.
a population, genetic differences among individuals provide the raw material on
which and other
mechanisms can act. Without such
differences, could not change over time, and hence the population could not .What factors can produce genetic variation among populations.Genetic
variation among populations can arise by natural selection if selection favors
different in different ; this might occur, for
example, if the different populations experienced different . Genetic variation among populations can also
arise by when the
genetic differences between populations are selectively .
Of all the mutations that occur in a population,
why do only a small fraction become widespread among the population’s members?
mutations occur in cells
that do not produce gametes and so are lost when the organism dies. Of mutations that do occur in cell lines that
produce gametes, many do not have a phenotypic effect on which can act. Others have a harmful effect and are thus
unlikely to increase in frequency because they decrease the reproductive
success of their bearers.
If a population stopped reproducing sexually
(but still reproduced asexually), how would its genetic variation be affected
genetic variation, whether measured at the level of the gene or at the level of
nucleotide sequences, would probably over time. During meiosis, and of chromosomes produce many new combinations
of alleles. In addition, a population
contains a vast number of possible mating combinations, and fertilization
brings together the gametes of individuals with different genetic
backgrounds. Thus, via crossing over,
independent assortment of chromosomes, and fertilization, sexual reproduction
reshuffles alleles into fresh combinations each generation. Without , new sources of genetic variation would be reduced, causing
the overall amount of genetic variation to drop.
What are the three sources of alleles to produce fresh combinations each generation.
In what sense is natural selection more
“predictable” than genetic drift? Natural selection is more
“predictable” in that it alters allele frequencies in a way: It tends to the frequency of alleles that increase the organism’s reproductive success in
its environment and the
frequency of alleles that decrease the organism’s reproductive success. Alleles subject to genetic drift increase or
decrease in frequency by alone, whether or not they are advantageous.
Distinguish genetic drift from gene flow in
terms of (a) how they occur and (b) their implications for future genetic
variation in a population. results from chance
events that cause allele frequencies to fluctuate at random from generation to
generation; within a population, this process tends to genetic variation over time. is the exchange of alleles between populations; a process that can
introduce new alleles to a population and hence may its genetic variation.
Explain why natural selection is the only
evolutionary mechanism that consistently leads to adaptive evolution.Although
both and can increase the
frequency of advantageous alleles in a population, they can also the frequency of advantageous
alleles or the frequency of
harmful alleles. Only consistently results
in an increase in the frequency of alleles that enhance survival or
reproduction. Thus, is the only mechanism that consistently causes
This quiz is intended for everybody who would like to test their knowledge about the European Voluntary Service program, but also for those who want to learn something new and improve their knowledge for this program. Have fun....
Questions: 19 | Attempts: 86 | Last updated: Mar 19, 2022