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Questions from the seminar:
* Q 14, Ch 13: Diploidy and balancing selection preserve genetic variation. See page 272
* Q 2, Ch 26: ups and down. See page 734
* Q 14, Ch 26: why species are vulnerable. Addition: specialists are more at risk than
generalists
Stuff from the forest
* Why is there silica still in Equisetum hyemale? Because it involves no costs for the plant to
have it. Selection has therefore not worked against it. Individuals with lower amounts of silica
has not been favoured in evolution
Ten rules in ecology
1.
Ecology is only understandable in the light of evolution
The awesome variation in behaviour, morphology, physiology...cannot be understood without
considering the evolutionary history and the selection pressures that are and have been
operating.
Example: pappus lengths in Hypochaeris radicata, rotfibbla, Cat’s ear.
Example: Equisetum hyemale, skavfräken, Rough Horse-tail.
2. Nothing happens ’for the good of the species’ or selection is at the level of the
individual
Natural selection will favour those genes which are passed on to the most offspring. Both
altruism and population regulation can be understood in terms of evolution acting on
individuals.
Example: pappus lengths in Hypochaeris radicata, rotfibbla, Cat’s ear.
3.
Genes and environment are both important
environment + genotype = phenotype
they interact!
Example: leaves of Ranunculus aquatilis, vattenmöja, Common Water-crowfoot.
4.
Understanding complexity requires models
Observation  question  hypothesis  test it  new observation  reformulate the
hypothesis.
Example: Starling feeding behaviour.
5. ’Story-telling’ is dangerous
Creativity should be encouraged in scientists at the level of constructing hypotheses. The
temptation to advance the hypotheses as facts should be avoided.
Example: Polar bears are white because they need to escape from their predators.
6.
There are hierarchies of explanations
Just beacuase we have found one explanation does not necessarily mean that there are no
others. All can be correct at the same time.
Example: Why do the trees fell their leaves in winter?
7.
There are multiple constraints on organisms
Physical & evolutionary
Example: The eyes of mammals and octopusses.
8.
Chance is important
Example: gap dynamics, floods (environmental stochasticity), population sizes (demographic
stochasticity). Relevant for conservationists.
9.
Ecology is a science
Free from political views. But is it? No!
Example: Our research topics are to a large extent goverend by what the present rulers of the
country wants. Example: At present less money to biodiversity research.
10.
The boundaries of ecology are in the mind of the ecologist
A good ecologist regards mathematics, chemistry, physics and other disciplines as tools
essential to the understanding of ecology.
Example: When studying the energetics of hummingbirds it is good to know something about
the physics of flight.
Example: When studying the City Forest it is good to know how to read a map.