eksamensoppgave i bi2033 – populasjonsøkologi - Institutt for biologi

Engelsk:
Question 1
a) In a small insular population of a passerine bird species Passer umulius where all
individuals die during their third year of living there is counted 100 0-age individuals in
the end of the breeding season. In the end of the breeding season two years later there are
225 0-age individuals, and 25 two years old individuals present. What is the stable
agedistribution in this population when we assume that survival rate is independent of
age
b) In another insular population of the same species one counts 16 individuals in two
consecutive years and one assumes that the population can be regarded as stable. How
large must the average clutch size be in this population if we assume that the age of
maturation is 1 year, the sex-ratio is 1:1, no age-dependent reproduction and the same
survival as in the larger population
c) In which of these two populations will the 0-age individuals have the larger contribution
to future population growth
d) Describe how the two main types of stochasticity that affects population growth in natural
populations will affect these two island populations differently.
e) The population in a) is monitored further and after 2 new years they count 250 0-age
individuals and 56 two years old individuals. All the assumptions in a) and b) are not
necessarily valid. Can you identify limiting and regulatory factors (mortality and
reproduction) in this population
f) The individuals of these two island populations belong to the same species, but on a third
island they appear together. It appears that descendants of the colonizers from the two
islands differ more morphologically compared to what the colonizers did in the first place.
Describe two explanatory models for such divergence in morphology.
Question 2
a) What do we mean by ”functional respons” Illustrate in a figure the 3 types that you
know, and explain the ecological mechanisms that generate each of the different patterns.
b) Explain (and illustrate with figures!) the different main types of harvesting-strategies.
Discuss advantages and disadvantages of these harvesting-strategies.
Question 3
Levins introduced the classic model of metapopulastion dynamics in 1969.
a) Describe Levins’ model and the different parameters that are included in the model.
b) What is required for a metapopulation to be viable or persistent (i.e. not going extinct)
c) What do you understand with the term ”rescue effect”
d) What do you understand with the term ”source-sink dynamics”
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Eksamensoppgaver 2010.doc