#Question id: 17265
#Unit 11. Evolution and Behavior
#Question id: 21241
#Unit 7. System Physiology – Animal
#Question id: 3429
#Unit 11. Evolution and Behavior
Which of the following is a behavioral pattern that results from a proximate cause?
#Question id: 23309
#General Aptitude
#Question id: 12960
#Unit 10. Ecological Principles
The Norway rat (Rattus Norvegicus), a widespread pest, was controlled for about a decade by the anticoagulant warfarin. This chemical substance, placed in food pellets, is absorbed by the intestinal tract and inhibits the clotting of blood. After a population decline for about 10 years, rat populations increased and stabilized. In one European population, as illustrated in the graph below, the percentage of rats resistant to warfarin has remained fairly stable over a number of years.
Resistance to warfarin is governed by a dominant autosomal gene, R. More than 15 percent of the resistant animals are heterozygous at this locus (Rr). The table below indicates the response to warfarin and relative reproductive fitness of individuals that are homozygous or heterozygous for the dominant gene (R). The RR individuals have a 20-fold increase in vitamin K requirement over individuals.