This document summarizes all the lectures for the course animal ecology from the second year course Animal Ecology on the Raboud University Nijmegen. This includes all relevant lectures.
Summary Animal Ecology
Lecture 1.1
How do organisms adapt to situations in the field, not only theoretical data. Learn to ask questions,
why, how, what is happening and take your own field in consideration.
Basic principles 1:
Everything starts with feeding, and it can stop with that if you are being eaten. Get your food,
without being eating in order to grow, develop and learn to finally reproduce. Everything we do is
those 4 things. It is the goal of life, biologically speaking.
Basic principle 2:
all matter that contains energy will be used sooner or later. When there is 1 individual that can make
use of certain energy, it will grow faster than the others, expand its population and dominate. Like
using fossil fuels
Basic principle 3:
Variation is self-sustainable, when there is variation it will sustain itself. Suppose we are all equal and
no one has an advantage, then nothing will happen and the situation will remain. If there is one
advantage to someone they will outcompete the rest and dominate the rest. You then not only have
to cope with abiotic changes, but also with biotic changes, you have to adapt yourself time after
time.
Species traits:
Limitation of the building plan (one head, 2 hands, legs), variation is ok, but to a certain extent at the
one hand. And using different types of variation at the other hand:
- Tolerance (cold) temperature needs to go up)
- Learn (to adapt) take a coat, shelter, to keep warm
- Phenotypical plasticity, (differences in appearance in individuals, like every human looks
differently)
- Genetic variation, (when it is genetically supported it can go from population to the rest
Phenotypical variation or plasticity means a variation in fitness, and fitness is the survival probability.
This is enforced by natural selection if you have a low fitness. When you select only phenotypically,
you can start over next generation because the population doesn’t gain anything. This is because the
traits changed by phenotypical plasticity isn’t genetic, so it won’t be transferred genetically.
Variation 1:
Descriptive way:
- What do we see? Differences?
- What is happening? In time
1. Demography is a description of the population of the species (50/50 males females)
Example Macoma baltica (shell animal) birds feed on it, too many birds, it was said that they should
be extinct. The problem was the mortality of the shell, the birds fed on the meat which regenerated
over time and thus the bird didn’t completely kill it.
,Variation 2:
focussing on the genetical basis (quantitative genetics)
- Which traits are subject
to selection? Is it
singular genes, or is it
complex reaction
norms: (Complex
reactions norms is the
mapping of the
genotype onto the
phenotype as a
function of the
environment)
- Reaction norms can be
a different in the way
they collect food
Variation 3:
Trade-offs where the currency is fitness. There is no one blank to compare. You have to compare
groups and differences and then you can decide what do the differences mean? G1 is growing fast,
whilst G2 is investing in defence mechanisms against being eaten, like needles or pins in plants which
takes extra energy. This is a trade-off, thus investing less energy in growing and more energy in
defence mechanisms, which means lower growth, but higher fitness.
Variation 4:
Lineage specific effects.
- Construction plan dictates the preconditions and the you can ask;
- How small can an egg be, or how big? DNA must be combined with some energy, like
Endoplasmic reticulum or mitochondria. What can the biggest size be? In humans an egg is
0,5 cm, the biggest an egg can be, the egg needs to go out of somewhere, the kiwi lays eggs
which are 40% the mass of their bodyweight.
- Stearns indicate that snakes can only lay eggs, which is a limitation, when it is not safe
outside to lay eggs, or predictable temperatures to lay eggs and develop, what do you do?
- Then you act like a viper, which is oviparous (lay developing eggs that complete their
development and hatch externally from the mother). Lizards are viviparous where there is
development inside their bodies.
- Why do these species keep the eggs inside?
1. Protect from predators
2. Differences in temperature, when the eggs are inside, the mother can look for places
which are warmer, for coldblooded creatures
Variation 5:
There are different types of variation, but how does the environment select. Variation is self-
sustainable so you have to co-adapt the living environment, but you also have to co-adapt to the
non-living environment.
,Lecture 1.2
And then what does variation in the environment contain?
- Rain, drought
- Temperatures, but within limits
Types of environmental variation:
- Predictable variation, with a predictable amplitude:
1. The predictability is pleasant because you can adapt
2. Rotation of the Earth around the Sun and tilt of the Earth’s axis of rotation
result in seasons per year
Close enough, and far enough away from the sun
Rotation around its own axis results in 24 hours which results in a
day and night rhythm
Rotation of the moon around the Earth in combination with the
Earth-Sun position and the Earth position gives the tidal rhythm
(twice a day, high tide, low tide)
Rhythm of once a day and twice a day.
2. Attenuation of the amplitude
1. Water in the liquid phase
2. Significant dampening of temperature during 24 hours and during the year
due to the water on earth.
3. Equalisation of temperature due to horizontal and vertical flow. The bigger
the land mass, the higher the temperature.
- Predictable variation, with an unpredictable amplitude
1. We know its getting colder, but we don’t know for how long or how cold it is going to
get.
- Unpredictable variation
1. Large scale
1. Earthquakes and tsunami’s
2. Volcanic eruptions ash in atmosphere and drop in temperatures.
2. Smaller scale
1. Rain showers, flooding, landslides
2. Extra cold or warm periods out of the season
3. Droughts
3. Attenuation of the amplitude
1. Vegetation layers dampens differences in temperature and moisture content
2. Thus removal of vegetation layers can have irreversible consequences
3. Some soils dry out irreversible (top layer of clay baked in the sun makes
permeability impossible
4. How do you adapt to this?
Relation environmental variation and life history
- Cycle of environment variation is only experienced by and individual when the lifespan
exceeds the cycle. Make the comparison, what is the lifetime of an individual in relation the
cycle
, 1. A tide cycle is already too long for a bacterium
2. A summer aphid will never experience a winter
- This all together is called life history, and this not just an individual, but species down the
line.
1. Comparisons is always relative
1. Related species lay more or less eggs, larger or smaller eggs, have brood care
or do not (protecting offspring)
2. If you have 1 generation per environmental cycle, each generation will have to
survive the unfavourable time, which is an obligatory adaptation. It becomes
optional if you have several generation per cycle, but for the species it must be
there.
Classification of biotopes and habitats can be done to:
- Distinguish between
predictable and
unpredictable
- (non)cyclical in time
- In space, continuous,
fragmented or even isolated
Quadrant of Southwood. (first
disperse, then diapause).
More from a species’ perspective :MacArthur and Wilson
r-select (r means rate of increase) aphids, a lot of offspring already prepared for next generation
K-select (K means carrying capacity) Albatross (one egg 2 years)
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