Spongy moths, Lymantria dispar, have four life cycle stages: egg, caterpillar, pupa and adult (Figure 1). Their populations may be severely impacted by nuclear polyhedrosis viruses (NPVs; figure 2). These viruses infect, and kill, caterpillars; eggs and adults are unaffected by them. In a population of spongy moths, there is a gene with two alleles, R and r . Individuals with one or two copies of the dominant allele, R , are resistant to NPV (it infects them but causes no symptoms and is harmless). Individuals with two copies of the recessive r allele are susceptible to NPV (it is 100% lethal to them). Initially a population consists of 1000 eggs and no other stages. There are 360 individuals (embryos inside the eggs) with the genotype RR, 480 individuals with the genotype Rr , and 160 individuals with the genotype rr . This question has two parts. Part a) If all caterpillars become infected with NPV and mortality due to NPV is the only factor causing evolution in this population, what will be the frequency of the R and r alleles in the population when the moths reach adulthood? Show all calculations. (Remember you must type your answer for Turnitin submission). Express your answers as proportions and round to two significant digits. Part b) When the survivors from part a) mate and have offspring, what will be the frequency of RR , Rr and rr genotypes in the resulting (second generation of) eggs? Remember NPV is the only thing causing evolution in this population. Show all calculations. Express your answers as a proportion and round to two significant digits.
.
Spongy moths- Lymantria dispar- have four life cycle stages- egg- cate.docx
1. Spongy moths, Lymantria dispar, have four life cycle stages: egg, caterpillar, pupa and adult
(Figure 1). Their populations may be severely impacted by nuclear polyhedrosis viruses (NPVs;
figure 2). These viruses infect, and kill, caterpillars; eggs and adults are unaffected by them. In a
population of spongy moths, there is a gene with two alleles, R and r . Individuals with one or
two copies of the dominant allele, R , are resistant to NPV (it infects them but causes no
symptoms and is harmless). Individuals with two copies of the recessive r allele are susceptible
to NPV (it is 100% lethal to them). Initially a population consists of 1000 eggs and no other
stages. There are 360 individuals (embryos inside the eggs) with the genotype RR, 480
individuals with the genotype Rr , and 160 individuals with the genotype rr . This question has
two parts. Part a) If all caterpillars become infected with NPV and mortality due to NPV is the
only factor causing evolution in this population, what will be the frequency of the R and r alleles
in the population when the moths reach adulthood? Show all calculations. (Remember you must
type your answer for Turnitin submission). Express your answers as proportions and round to
two significant digits. Part b) When the survivors from part a) mate and have offspring, what will
be the frequency of RR , Rr and rr genotypes in the resulting (second generation of) eggs?
Remember NPV is the only thing causing evolution in this population. Show all calculations.
Express your answers as a proportion and round to two significant digits.
