Read the following passage from the Biology Department at University of California, Berkeley. Northern elephant seals have reduc
ed genetic variation because hunting by humans reduced their population size to as few as 20 individuals at the end of the 19th century. Their population has since rebounded to over 30,000, but their genes still carry the marks of this near extinction: they have much less genetic variation than a population of southern elephant seals that was not hunted as intensely. Which of the following best describes how the population has evolved? a. The population has not evolved because there was no change in allele frequencies. b. The population has not evolved because it has grown. c. The population has evolved because it has grown. d. The population has evolved because there was a change in allele frequencies.
The population has evolved because there was a change in allele frequencies.
Explanation:
The evolution may be defined as the process of the change of the species characteristics with the passage of the time. The natural selection, mutation and the genetic drift might cause the evolution.
The population might have evolved as the allele frequencies has changed from the generation to the generation. Although the variation among the population is quite less but the variation is still enough for the evolution of the elephant seals.
Viscosity is a property of liquid that has resistance between liquid molecules. Those liquids having strong force of attraction between their particles has a viscosity whereas those liquid substances have weak intermolecular force of attraction between the particles has low viscosity. For example, water has low viscosity as compared to honey.
It is useful for an ecologist to identify the keystone species in an ecosystem because the keystone species is important to maintaining the stability of an ecosystem, and any changes in the keystone species population shows that there is changes in ecosystem health.
