The gene that is mutated in cases of cystic fibrosis encodes an ion transporter protein normally expressed in the respiratory and digestive tracts along with other locations. Individuals homozygous for the most common mutation in this gene (ΔF508) died at very early ages prior to the advent of advanced medical intervention. Despite this, the mutation exists at relatively high frequency in populations of European descent. One potential explanation is that heterozygotes for such mutations may be relatively immune to the lethal effects of diseases such as typhoid fever. Which statement below is most accurate?

#Question id: 13138

#Unit 10. Ecological Principles

#Question id: 13137

#Unit 10. Ecological Principles

#Question id: 13136

#Unit 10. Ecological Principles

The figure below illustrates the relationship between population density in the present generation (Nt) and population equilibrium density of this population in the next generation (Nt+1). The dashed reference line has a slope of 1. Which of the following represents equilibrium density of this population?

#Question id: 13134

#Unit 10. Ecological Principles

Which  of  the  graphs  below  represents the  relationship between  population  size  (N)  and  population  growth  rate (dN/dt) for a population showing exponential growth?

#Question id: 13133

#Unit 10. Ecological Principles

The diagram below depicts three general types of survivorship curves. Only the form of the curve is important, not its absolute scale. Which of the following statements is LEAST likely to be true?

#Question id: 13132

#Unit 10. Ecological Principles

Biologists performed an experiment with flies to examine the effects of population size on the maintenance of genetic variation  and  on  egg-to-adult survival.  From  a  large  source  population, they  randomly  assigned  eggs  to  three experimental  populations  of  size  N,  equal  to  20,  60,  and0100.  For  later  generations,  they  collected  N  eggs  from each  population  and  moved  them  into  identical  vials  that  co0ntained  f2re0sh  me4d0ium.  Th6e0y  coun8te0d  the  number  of adult flies that emerged and used tissue samples from the adults for genetic analyses. Genetic variation was measured by  scoring  alleles  at  several  polymorphic  loci  and  expressed  as  the  average  number  of  alleles  at  those  loci.  The results are summarized in Figure 1 and Figure 2 below.

Which other process appears to have substantially influenced the outcome of this experiment?