Ecology
The scientific study of the distribution and
abundance of organisms and the interactions
that determine distribution and abundance
Begon, Harper, Townsend, 2006, Ecology, Blackwell
Ecology is the scientific study of the distribution and abundance of organisms and the
interactions that determine distribution and abundance
Lecture outline
1. The evolution of life and life histories
2. The flux of energy and matter
3. Individuals and populations
4. Ecological communities
5. Positive and negative species interactions
6. Trophic networks
7. Distributions in time
8. Distributions in space
9. Function and diversity
10. The human impact
Literature
Literature
Ecological slideshows
http://www.slideshare.net/marglema9/ecol
ogy-1
Ecological e-books
http://www.ebooksdownloadfree.com/d
ownload/ecology-1.html
The scientific study of the distribution and abundance of organisms and the interactions that
determine distribution and abundance
The scientific method
Deduction
Top down logic
Theory
Theory
Hypotheses
Testable
predictions
Hypothesis
modification
Hypotheses
Testable
predictions
Observations
Hypothesis
testing
Observations
Induction
Bottom up logic
A theory is used as a testable set of logically coherent hypotheses
Hypothesis are assumed of being falsifiable
The core of a theory is difficult to falsify because it can always be
modified in a way to match empirical observations
In the natural sciences we often do not test theories.
We treat theories as an expectation under predefined conditions and are interest in the
deviation of reality from expectation.
Theory
Observations
Modify the theory to match
observations
Modify
theory
The core of any theory is
hard to falsify.
Difference
too large
Difference
(Residual)
It is impossible to veryfy
the core.
Conditions of the
theory not met
The new hypotheses do
not directly follow from
our theory. They contain
an empirical element.
Hypotheses,
testable
predictions
In this case the theory
becomes untestable
and therefore
unfalsifiable.
Theory predicts the number of insect species to rise to the power of 5/4 with plant
species richness
We use c2 or Kolmogoroff Smirnoff
tests to infer whether the theory
matches the data.
Residual
𝑆𝑖𝑛𝑠𝑒𝑐𝑡 = 𝑆𝑝𝑙𝑎𝑛𝑡
5/4
Often these formal tests will reject the
theory.
Gaston 1992
We do not test the theory.
We use the theory and the empirical
data to study additional factors.
We calculate the residuals and regress
them with the area under study.
We detect four areas with much too
low and one area with too high species
richness of insects.
What is ecology?
The term ecology was coined 1866 by
Ernst Haeckel in his habilitation lecture.
Oikos: home
Ecology deals with patterns and with processes in the living world.
Aims of ecology:
Ernst Haeckel
(1834-1919)
Describing the place of living beings in their environment
Explaining abundances, distributions, and interactions of living beings
Predicting the changes in the abundance and distribution of living beings
Controling changes in the abundance and distribution of living beings
Autecology deals with the life history of single species
Population ecology deals with the abundance and
distribution of a group of interbreeding organisms
Community ecology deals with a group of interacting species
Evolutionary ecology deals with the evolutionary history of
todays ecological systems
The basic units of
ecological research are
Genes
Individuals
Populations
Species
The scientific study of the distribution and abundance
of organisms and the interactions that determine
distribution and abundance
Distribution and abundance might relate to
genes, individuals, populations, or species
The manifold of genes or species is called
diversity.
Applied to all living beings we speak of
biodiversity
Charles Robert
Darwin
(1809-1882)
Alfred Russel
Wallace
(1823-1913)
Number of marine families
2500
N u m b e r o f fa m ilie s
z
M as s e xtinc tio ns
2000
1500
1000
500
0
-6 0 0
-5 0 0
E
K
-4 0 0
O
S
D
-3 0 0
C
P
-2 0 0
T
-1 0 0
J
Kr
0
Pa N
Allopatric , peripatric, and sympatric speciation
Allopatric speciation is generally slow
Spatial breeding barrier
Species
home
range
Peripatric speciation might be fast
Time
Allopatric and peripatric speciation: New species emerge by genetic divergence in
geographically isolated regions
Sympatric speciation: New species emerge within the same habitat by any other breeding
barrier. The include behavioural, resource use, or morphological barriers.
The diversification of species
Tinamou
South Amercia /
Africa
Ostrich
Rhea
Spotted Kiwi
Great Kiwi
North Island Kiwi
South Island Kiwi
Cassowary
New
Zealand
Australia
80
Time
Tinamou
Rhea
Emu
0
Cassowary
Low diversity of nine species
Comparably high genetic diversity
Today’s biodiversity is largely caused by evolutionary history and plate tectonics
Zosterops
poliogaster
Zosterops
abyssinicus
Postglacial colonization of Europe
During the last 10,000
years Central and
Northern Europe was
recolonised from
multiple glacvial
refuges where species
survived the ice age.
We reconstruct
colonisation
routs by the
analysis of
genetic diversity
across Europe.
Because
colonising
populations are
often small they
are generically
impoverished
(founder effect).
The refuges are
centres of gentic
diversification.
Major refuges where:
The Maghreb
Spain
Turkey
Sicily
Cyrpus
Crete
Hewitt G.M. 1999. Postglacial recolonisation of European biota.
Biol. J. Linn. Soc. 68: 87-112.
Postglacial colonization of Europe
Carabus auronitens
Colonisation gradient
Founder effects
Ordered
genetic loss
Populations
Relict
populations
Vicariant
(scattered)
genetic loss
Colonisation gradient
The allele - sites matrix is sorted according to allele richness
Postglacial colonisation of European Tenebrionidae (Coleoptera)
Reconstruction
of postglacial
colonisation
using
phylogenetic
relatedness of
species
Three major postglacial refuges with high numbers of
endemics and high rates of glacial speciation
Three major
colonisation routes
Past and present fragmentation
Distribution of South American rainforest refugia (100,000 to 20,000 BP) based on the
overlap of postulated refugia for birds, butterflies and plants. Shading represents probability
of locations being refugial.
Whitmore, T.C. ,Prance, G.T. 187. Biogeography and Quaternary History in Tropical America. Blackwell.
Convergent evolution by similar selective pressures
Ecological niches
Charles Elton, 1900-1991
Joseph Grinnell, 1877-1939
The niche is the role a
species plays in a
community, rather
than a habitat.
The niche is the sum of the
habitat requirements that allow a
species to persist and produce
offspring.
Profession
G Evelyn Hutchinson, 1903-1991
The niche is an n-dimensional
hypervolume, where the
dimensions are environmental
conditions and the resources that
define the requirements of an
individual or a species to practise
Two niche dimensions of a
plant
Optimum
Suboptimum
Water
A given habitat filters species according
to the abiotic conditions
Performance
Light
Place
Performance of a species
Reproduction
Growth
Survival
Condition
Performance
Specialist
species
Generalist species
Condition
Ecological niches emerge from differences in performance along the gradient of habitat
conditions
Formally a niche is the place of a species within a multidimensional hypervolume spanned
by all resources used by this species.
Generalist species have relatively broad niches in comparison to specialist species.
Performance
A habitat is the place where a species occurs.
Do not mismatch habitat and niche!
Realized
niche
Fundamental
niche
Condition
The carbon isotope ratio of body tissues (13C ⁄ 12C = δ13C) depends on resource width, while
the nitrogen isotope ratio (15N ⁄ 14N = δ15N) increases in insects with trophic level.
Ground beetles (Carabidae) on Mazurian lake islands
Trophic position
top
basal
Error bars denote a standard error
Zalewski et al. 2013,
Ann.Zool.Fenn
Number of resources
Parts of the species are well segregated in trophic niche space, while another part of
species highly overlaps in resource use.
The plot shows also three different guilds of species with similar resourse use.
The basic resources of life
Carbon
source
Proton
source
(CH2O)n
(CH2)nH2
Heterotroph
CA
Autotroph
CO2
Organotroph
+ D--H+ +
Lithotroph
Water,
Hydrocompounds
Energy
storage
Energy
Organic
compounds
Electron
acceptor
Energy
storage
Facultative store of
energy excess
Light
Phototroph
E + S → (CH2O)n + DA + ES
Reduction
Oxidation
Organic
compounds
Waste
Chemotroph
Chemical
reaction
6CO2 + 6H2O + light + ADP → C6H12O6 + 6O2+ ATP
Green plants, Cyanobacteria
C6H12O6 + C6H12O6 + O2 + ADP → (CH2O)n + CO2 + H2O + ATP
Animals, fungi
CO2 + NH3 + O2 + ADP → (CH2O)n + HNO2 + H2O ATP
Nitrosomonas bacteria
Resources and feeding types
Energy
source
Electron
donator
Organic
(Organo)
Light
(Photo)
Inorganic
(Litho)
Radioactivity
Inorganic
(Litho)
Organic
(Organo)
Chemical
compound
(Chemo)
Inorganic
(Litho)
Carbon
source
Trophic group
Organic
(Hetero)
Photoorganoheterotrophs
Inorganic
(Auto: CO2)
Photoorganoautotrophs
Organic
(Hetero)
Photolithoheterotrophs
Inorganic
(Auto: CO2)
Photolithoautotrophs
Cyanobacteria, green plants
Inorganic
(Auto: CO2
Radiolithoautotrophs
Firmicutes heat tolerant
Eubacteria
Organic
(Hetero)
Chemoorganoheterotrophs
Animals, fungi, green plants
Inorganic
(Auto: CO2)
Chemoorganoautotrophs
Spirochaetes
Organic
(Hetero)
Chemolithoheterotrophs
Inorganic
(Auto: CO2)
Chemolithoautotrophs
Purple non-sulfur bacteria
Iron bacteria, Archaea
Trophic niche spaces in eukaryotes
The specific trophic needs of organisms define
their trophic niche.
Trophic niches are generally not species specific.
They are highly variable in time and space.
Animals
Carnivores
Green plants
Producers
Latin
Greek
Herbivore
Carnivore
Fungivore
Omnivore
Saprovore
Microvore
Bacteriovore
Phytophage
Zoophage
Mycetophage
Pantophage
Saprophage
Microphage
Bacteriophage
Herbivores
Parasites
Fungivores
Omnivores
Mineralisers
Saprovores
Fungi, slime moulds,
animals
Omnivores are
animals that feed on
other animals and
plants