This is an English summary of the book Essentials of Animal Ecology (4th edition) including all lecture notes and additional reading material from the subject Introduction in Animal Ecology (REG21306). It covers all subjects important for the exam in just 30 pages.
It is a bit too succinct, and there is little explanation
Door: matthijsmackaay • 4 jaar geleden
Zeer compacte samenvatting waardoor het eerder een begrippenlijst is met uitleg van concepten. Maar dat is eigenlijk ook wel te zien in het voorbeeld. Persoonlijk waardeer ik iets meer uitleg.
Part 1: Introduction
Chapter 1: Ecology and how to do it
1.1 What is Ecology?
Ecologists examine the interaction between life and the physical environment (eg. How organisms
affect material fluxes in nature)
Ecology Definition: “the scientific study of the distribution and abundance of organisms, the
interactions that determine that distribution and abundance, and the relationship between
organisms and the transformation and flux of energy and matter.”
Applied ecology:
How to optimize the rate at which food is collected from natural environments in a
sustainable way
How domesticated plants and animals can best be managed so as to maximize rates of return
How food organisms can be protected from their own natural enemies
How to control the populations of pathogens and parasites that live on us
Pure ecology:
Scientific analysis
Ecologist try to explain and understand. Explanation can either be ‘proximate’ or ‘ultimate’.
Proximate: an explanation in terms of what is going on ‘here and now’.
Ultimate: An explanation in evolutionary terms (how the traits came to be)
Often, ecologists are interested in what will happen to a population of organisms under a particular
set of circumstances, and on the basis of these predictions to control, exploit or conserve the
population.
1.2 Scales, diversity of approaches, and rigor
Ecological phenomena occur at a variety of scales/hierarchical levels.
Populations are functioning groups of individual organisms of the same species in a defined
location
Communities consist of all the species populations present in a defined location
Ecosystems include both the community of organisms and the physical environment in which
they exist
The biosphere is the totality of all of life interacting with the physical environment at the
scale of the entire planet
Population ecology: stresses the trends and fluctuations in the number of individuals of a particular
species at a particular time and place, as determined by the interactions of birth and death rates and
the interactions between the populations themselves (predator/prey).
Community ecology: focusses on questions such as ‘what controls the diversity of species in a given
area.
Ecosystem ecology: strives to understanding of entire lakes, forests, wetlands, or other portions of
the Earth in terms of energy and material inputs and outputs.
Across all scales of biological hierarchy, three generalities emerge:
, 1. The properties observed at a particular level arise out of the functioning of parts at the level
below
2. To understand the mechanistic reasons that a particular property is observed at any level of
biological organization, a scientist needs to look at the next lowest level or organisation
3. Properties observed at a given level of organisation may be predicted without fully
understanding the functioning at lower levels
Ecological succession: the successive and continuous colonization of a site by certain species
populations, accompanied by the local extinction of others
May be studied over a variety of time scales
The appropriate time scale for ecological investigation varies with the question to be
answered
The diversity of ecological evidence
Ecological evidence comes from different sources and approaches:
Observations
Experiments
Mathematical models
Manipulative field observation: manipulating a species/group/environment in order to test a
hypothesis
Comparative field observation: explicitly comparing the same sort of data from many different sites
‘what distinguishes science is that it is based not simply on assertions, but rather on conclusions
resulting from investigations that test specific hypotheses, and to which we can attach a level of
confidence, measured on a agreed-upon scale.’
Many ecological field experiments rely on a large number of replicates for each treatment
for scientific results
Ecology relies on obtaining estimates from representative samples
1.3 Ecology in practice
Study on invasive species of trout in new Zealand: It resulted in a higher level of algae, invertebrate
and fish productivity.
Study on vultures dying: Caused by diclofenac using in domestic animals. This was then researched
using a mathematical model.
1. Models can be valuable for exploring scenarios and situations for which we do not have real
data
2. They can be valuable too, for summarizing our current knowledge and generating predictions
in which the connection between current knowledge, assumptions and predictions is explicit
and clear
3. In order to be valuable in these ways, a model does not have to be a full and perfect
description of the real world – it seeks to incorporate approximations
4. Caution is therefor necessary, but applied cautiously can be useful
5. A model is inevitably applied with much more confidence once it has received support from
real sets of data
,Chapter 2: Ecology’s Evolutionary Backdrop
2.1 Evolution by natural selection
What is evolution?
Evolution = change in life forms over time in the heritable characteristics of a population or
species.
Evolution is inevitable.
The direction of the evolution is defined by the most prosperous and most reproductive
individuals.
What are the underlying processes?
The components of evolutionary change:
o Variation occurs within population
o Variation is heritable
o Differential reproductive success
Populations grow at a great rate, yet most individuals die before reaching
reproductive age; individuals reproduce at less than the maximum rate
Different ancestors have different numbers of descendants
Charles Darwin and Alfred Russel Wallace both independently produced the idea of natural selection.
2.2 Evolution within species
Divergence within species will only occur if:
1. There is sufficient heritable variation
2. The forces of selection favouring divergence are strong enough to counteract mixing and
hybridization of individuals from different sites
Countergradient variation (Scandinavian frogs)
Hybridization: The production of offspring sharing the characteristics of both parents
Reciprocal transplant experiments: Comparing their performance when growing up at the original
habitat vs when growing in the habitat of the other population to investigate local adaptation
Industrial melanism: (very local adaptation) phenomenon in which black forms of species of moths
and other animals have come to dominate heavily industrial areas (due to excessively producing
black melanin)
The most dramatic forms of evolution have been driven by pollution.
Co-evolve: Two species’ evolution drives the other two evolve as well
Mutualist: Positively beneficial for both parties
Antagonistic: eg. Parasite vs host
2.3 The ecology of speciation
Species are organisms that can breed together in nature and can produce fertile offspring
Biospecies are recognised when they have diverged enough to prevent them from forming
fertile hybrids if and when they meet
Ecological speciation: due to a change in the environment
, Speciation where there is a source of divergent selection;
And a means of reproductive isolation
o Due to the difference in interaction with environment or other species
The different stages of divergence:
1. Isolation of subpopulations genetic adaptation to the
environment
2. A degree of reproductive isolation builds up between them
a. Prezygotic isolation: difference in courtship causes no
offspring at all
b. Post-zygotic isolation: offspring has lower reproduction
3. The two populations meet, reproductive isolation is further favoured
by natural selection due to lower fitness of hybrid offspring
4. Breeding barriers define separate species
Allopatric speciation (1 & 2)
When a population is completely split into isolated populations (islands)
Local endemics: Species known from only one island or area
Endemic species evolve because they are isolated of the originated species or other species
with which they might hybridize
Ring species: Distinct forms that are capable of producing fertile offspring but that are not entirely
species.
Sympatric Speciation (4)
No initial geographic isolation of populations
Few convincing examples
2.4 The effects of climatic change on the evolution and distribution
of species
Over the past million years, the earth has mainly
be very cold. The current floras and faunas are
thus quite unusual.
The species composition is still constantly
changing.
Richness in species tends clearly to be greatest
where stability was highest
Parallel Evolution: Populations long isolated
from common ancestor have followed similar
patterns of diversification.
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