Ecology I Theory
Course unit 1
Lecture 1: Ecology and evolution: the origin and dissemination of
species
Erik Poelman
What is ecology and what is the importance of ecological
knowledge?
Ecology: 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.
Ecology is central to 8 out of 17 global goals:
2. No hunger
6. Clean water and sanitation
7. Clean energy
11. Sustainable cities and communities
12. Responsible consumption
13. Protect the planet
14. Life below water
15. Life on land
Ecology is trying to understand the processes that explain patterns
Processes interactions
Ecology starts with:
- Observations
- Discovering patterns
- Asking questions
- Unravelling underlying processes
By various approaches:
- Observations in the field
- Controlled field or lab experiments
- Mathematical models
- Molecular and chemical analysis
Example
- Statistics: reliability of findings
Ecological question: Why do wood lice live in a dark and humid
In ecology research is done by asking
environment?
ecological questions.
These can be explained in 2 ways: Proximate explanation:
“Wood lice can assess the amount of light and moisture and actively
Proximate explanation: cause-effect
move to dark, damp locations.”
(causal-analytical) how?
Ultimate explanation: function Ultimate explanation:
(evolutionary processes) why? “Wood lice have adapted to this environment, which protects them
better against predators and persistent drought.
,Ecology and evolution: speciation and dispersion
To understand ecology you have to look back in time.
1. First the earth had a volcanic atmosphere, where almost no life could flourish
2. The next important step: photosynthesis. Plants started to release oxygen into the
atmosphere.
Organisms are opportunistic use a resource that almost no other organisms uses
Plants did this with oxygen
3. Anaerobic organisms living in an almost oxygen-free environment because they do not
tolerate oxygen.
4. Free oxygen
5. Ozone as a shield against UV
6. Sexual reproduction (recombination) combination of different organisms
7. Colonisation on land. Life first started in the water and eventually
went to the land. Here they met with barriers due to dehydration
and gravity
Relation ecology and evolution
By Charles Darwin (1809-1882) and Alfred Russel Wallace (1823 – 1913)
1. Individuals within a population are not identical
2. Part of the variation between individuals has a genetic basis and is
heritable
3. Not all individuals are able to reproduce, so populations contain a
subset of the possible descendants of the previous generation
4. Individuals differ in the number of descendants and therefore
contribute differently to the hereditary characteristics of a next
generation
,Fitness: relative contribution of an individual to next generation
Genotype: All genetic characteristics of an individual that together determine the characteristics of
the individual
Phenotype: the actual expressed characteristics of the individual (in that particular environment)
Phenotypic plasticity: the extent to which variation in phenotypes of an individual is expressed
depending on the environment
Environments creates variance in phenotype
Co-evolution: mutual selection of organisms in interaction
E.g. the Mustard plant’s defence with glucosinolates,
eventually followed with an adaptation from butterflies with
resistance.
,Ecotypes: populations of a species with different phenotype adapted to local conditions (similar to
subspecies)
E.g. the Silene vulgaris (Bladder campion/Blaassilene) with zinc as an environmental factor
Little exchange and strong selection leads to ecotypes
Viola lutea - Violo calaminaria
Long-term isolation can lead to speciation: no hybrids with fertile offspring occur between the
species.
Effects of complex patterns of allopatric speciation:
Subspecies: Populations of a species that differ in characteristics, but produce fertile offspring when
hybridised
Ecotypes: Populations of a species with a different phenotype adapted to local conditions (similar to
subspecies)
Ring species: Complex of subspecies which can interbreed with adjacent populations, but for which
“end” populations are too distantly related to interbreed
Allopatric speciation: species arise in isolation (e.g. on an island)
Sympatric speciation: species arise when they live side-by-side
, Allopatric speciation:
Sympatric speciation:
For example a certain genotype breeds earlier then another. Or certain fish live in other
parts/different depths of a lake.
Pangea
Laurasia &
Godwana
Course unit 1
Lecture 1: Ecology and evolution: the origin and dissemination of
species
Erik Poelman
What is ecology and what is the importance of ecological
knowledge?
Ecology: 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.
Ecology is central to 8 out of 17 global goals:
2. No hunger
6. Clean water and sanitation
7. Clean energy
11. Sustainable cities and communities
12. Responsible consumption
13. Protect the planet
14. Life below water
15. Life on land
Ecology is trying to understand the processes that explain patterns
Processes interactions
Ecology starts with:
- Observations
- Discovering patterns
- Asking questions
- Unravelling underlying processes
By various approaches:
- Observations in the field
- Controlled field or lab experiments
- Mathematical models
- Molecular and chemical analysis
Example
- Statistics: reliability of findings
Ecological question: Why do wood lice live in a dark and humid
In ecology research is done by asking
environment?
ecological questions.
These can be explained in 2 ways: Proximate explanation:
“Wood lice can assess the amount of light and moisture and actively
Proximate explanation: cause-effect
move to dark, damp locations.”
(causal-analytical) how?
Ultimate explanation: function Ultimate explanation:
(evolutionary processes) why? “Wood lice have adapted to this environment, which protects them
better against predators and persistent drought.
,Ecology and evolution: speciation and dispersion
To understand ecology you have to look back in time.
1. First the earth had a volcanic atmosphere, where almost no life could flourish
2. The next important step: photosynthesis. Plants started to release oxygen into the
atmosphere.
Organisms are opportunistic use a resource that almost no other organisms uses
Plants did this with oxygen
3. Anaerobic organisms living in an almost oxygen-free environment because they do not
tolerate oxygen.
4. Free oxygen
5. Ozone as a shield against UV
6. Sexual reproduction (recombination) combination of different organisms
7. Colonisation on land. Life first started in the water and eventually
went to the land. Here they met with barriers due to dehydration
and gravity
Relation ecology and evolution
By Charles Darwin (1809-1882) and Alfred Russel Wallace (1823 – 1913)
1. Individuals within a population are not identical
2. Part of the variation between individuals has a genetic basis and is
heritable
3. Not all individuals are able to reproduce, so populations contain a
subset of the possible descendants of the previous generation
4. Individuals differ in the number of descendants and therefore
contribute differently to the hereditary characteristics of a next
generation
,Fitness: relative contribution of an individual to next generation
Genotype: All genetic characteristics of an individual that together determine the characteristics of
the individual
Phenotype: the actual expressed characteristics of the individual (in that particular environment)
Phenotypic plasticity: the extent to which variation in phenotypes of an individual is expressed
depending on the environment
Environments creates variance in phenotype
Co-evolution: mutual selection of organisms in interaction
E.g. the Mustard plant’s defence with glucosinolates,
eventually followed with an adaptation from butterflies with
resistance.
,Ecotypes: populations of a species with different phenotype adapted to local conditions (similar to
subspecies)
E.g. the Silene vulgaris (Bladder campion/Blaassilene) with zinc as an environmental factor
Little exchange and strong selection leads to ecotypes
Viola lutea - Violo calaminaria
Long-term isolation can lead to speciation: no hybrids with fertile offspring occur between the
species.
Effects of complex patterns of allopatric speciation:
Subspecies: Populations of a species that differ in characteristics, but produce fertile offspring when
hybridised
Ecotypes: Populations of a species with a different phenotype adapted to local conditions (similar to
subspecies)
Ring species: Complex of subspecies which can interbreed with adjacent populations, but for which
“end” populations are too distantly related to interbreed
Allopatric speciation: species arise in isolation (e.g. on an island)
Sympatric speciation: species arise when they live side-by-side
, Allopatric speciation:
Sympatric speciation:
For example a certain genotype breeds earlier then another. Or certain fish live in other
parts/different depths of a lake.
Pangea
Laurasia &
Godwana
