Print this page
Syllabus Schedule Assignments Modules Study Materials Login to Moodlethis link opens up a new browser window

Ecology -- Practice Problems

5 points

Due by Monday, November 11, 2013.

  1. Pablo decides to send his Canadian pen-pal Jacques some Queen Long Wing caterpillars for his birthday.  Pablo encloses instructions and tells Jacques it will take 35 days for them to hatch into butterflies.  Jacques follows Pablo's directions, but things seem to be taking longer than expected.  At the end of 35 days, Jacques' butterflies still have not emerged.  If Pablo's mother keeps their Honduran abode at a constant 77 degrees, while Jacques' mother keeps their cabin at 67 degrees, how much longer should Jacques expect to wait before his butterflies emerge?  Assume the butterflies' developmental threshold is 5 degrees.

  2. A female grape root borer, Vitacea polistiformis, will produce an average of 450 eggs (lifetime output).  If 90% of these are fertile and hatch into young larvae, how many would have to die of starvation, predation, and disease in order for this population to remain stable ("R"=1)?

  3. You just made road kill out of a opossum on a warm summer night.  The race is now on in the insect world to turn your road kill into a nursery.  A blow fly and a carrion beetle arrive at the new road kill simultaneously.  The carrion beetle has a developmental threshold of 7° Celsius and requires 350 day-degrees to become an adult.  The blow fly has a developmental threshold of 14° Celsius and requires 275 day-degrees to become an adult.  If the average temperature for this time of year is 26° Celsius, which insect babies become adults first?

  4. Bud moths have three generations per year.  The sex ratio is balanced (1:1) and females lay an average of 25 eggs.  Eighty percent of the larvae are killed by bird predation each generation.  Egg parasitism is 20% in the first generation and doubles in each subsequent generation (parasitized eggs do not hatch).  Construct a life table for this species and calculate the value of "R" for each generation.

  5. On the afternoon of June 22, the body of a male caucasian was found in the woods near Yates Pond.  The corpse was examined by police and immediately shipped to the morgue where it was stored at 38°F until an autopsy could be performed.  Dr. Scarpetta, the chief medical examiner, conducted the autopsy two days later (after returning from a vacation in Puerto Rico).  She found mature blow fly maggots (beginning to pupate) inside the cranial cavity.  The blow flies have a developmental threshold of 42°F and a development time (egg to pupa) of 285 degree-days (°F).  Use the average daily temperatures from the chart below to help Dr. Scarpetta determine when the victim died (or was murdered).
    June Date:   10  11  12  13  14  15  16  17  18  19  20  21  22  23  24
    Mean Temp:   69  71  66  74  72  70  77  69  80  71  70  74  76  69  72

Submit your answers in class or e-mail to