Evolution over time has allowed them to adjust to their surroundings. Birds can also survive on eating less/smaller things whereas reptiles usually have to eat more to survive. Also, birds eat a lot of plants while reptiles eat a lot of meat. 
        
             
        
        
        
Wild Bedbugs become insecticide resistant because of the mutations and natural selections. 
<h3><u>Explanation</u>:</h3>
As the huge amount of pesticides and insecticides are sprayed in the rooms for cleaning, the pests and insects like bedbugs dies in huge portions because of the toxin. But some of the bedbugs remain alive as they have mutations that help them to detoxify the toxins given, or bypass the metabolic processes so that the toxins don't hamper them much.
Now as the population becomes very small(bottle neck effect), the nature selects these organisms over the other to propagate more sufficiently and enormously. As the nutrients and supplies are also available, so the bedbugs don't suffer any lack of nutrition which can be a determining factor of their population.
Thus the wild bedbugs become resistant to insecticides while the experimental one remain succeptible to insecticides. 
 
        
             
        
        
        
Answer:
im pretty sure it is underpopulation.
 
        
             
        
        
        
Answer:
Population size decreases 
 
        
             
        
        
        
Answer
            The correct option is B.
Explanation
           Ecological succession of any species is composed of following stages:
A. Migration
             The movement of species from one place to another location for the purpose of setting permanently o temporary is known as migration
. Forexample
              Siberian crane (<em>Leucogeranus leucogeranus</em>) that live in the arctic tundra of eastern and western Russia. The eastern population of birds migrate to china while western population of these birds migrate to Iran, India and Nepal during winter season.
B. Ecesis
          The complete establishment of species in new habitat that was completely barren or left barren due to some catastrophe is known as Ecesion. This process is dependent upon the climatic, edaphic and biotic factors. The success of plant depend upon some of the adaptations to withstand the unfavorable conditions which includes both biotic and abiotic conditions.
Forexample
                The process of succession in xerosphere start on barren area from pioneer stage covered by crustose lichen, then foliose lichen followed by moss stage, herbaceous stage and a last by shrub stage.
C. Nudation
        The initiation of new species by major environmental disturbance such as volcano eruption is known as Nudation.
D. Reaction
             It represents the effect of established species on the habitat. Forexample plants alter habitat condition as they grow. They extract raw materials from the environment in large amounts and return metabolic wastes. The waste accumulates in large amounts and differ from the original raw materials, thus altering the environment.  
E. Competition
              The phenomenon which involves struggle for existence between two or more individuals growing in same area, that make excessive demand that are similar in nature on the soil is known as competition.
Such struggle may be in between same species or different species. The competition may be interspecific or intraspecific. Because of completion the weak individuals are eliminated as strong ones are retained.