Ecology 1 Flashcards
Ecology
the branch of biology that deals with the relations of organisms to one another and to their physical surroundings
evolution by natural selection
survvival of the fittest
Proximate explanation:
cause-effect (causal-analytical) (how)
“Wood lice can assess the amount of light Isopoda and moisture
and actively move to dark, damp locations.
Ultimate explanation
function (evolutionary processes) (why)
“Wood lice have adapted to this environment,
which protects them better against predators and persistent drought.
Earth’s history important events
- advent of anaerobic bacteria
- photosynthesis:
- free oxygen
- ozone as a shield against UV
- sexual reproduction (recombination)
- life on land
how does evolution through natural selection work?
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
Genotype
All genetic characteristics of an individual that together determine the
characteristics of the individua
Phenotype
The actual expressed characteristics of the individual
Phenotypic plasticity
the extent to which variation in phenotypes of an individual is
expressed depending on the environment
what does evolution within a species depend on ?
local adaptation
Co-evolution
mutual selection of
organisms in interaction
process of evolution within a species
Initial situation: environment - gradient and individuals
with different genetic characteristics
Little exchange and strong selection leads to ecotypes:
Long-term isolation can lead to speciation: no hybrids with
fertile offspring occur between the species
Ecotypes
(similar to subspecies) populations of a species
with a different phenotype adapted to local conditions
Subspecies
populations of a species that differ in characteristics, but produce fertile
offspring when hybridised
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 (for example
on an island
Sympatric speciation
Species arise when they live side-by-
side
Phytochoria
Classification according to the occurrence of orders of higher plants
(taxonomic characteristics)
European phytochoria
climate is the determining factor for species composition
zoographic regions
Zoogeographic regions do not completely overlap with phytochoria: due to later terrestrial
colonisation, animals did not dissipate until the plates (continents) were further apart
Endemic species:
Species that only occur locally
Parallel evolution
Starting point: common ancestor, but
geographically separated
Organs: analogue (=the same form and
function) and homologue (=developed from
the same ancestral organ)
Example: placental mammals and marsupials
(until 100 million years ago
Divergent evolution
Starting point: common ancestor
Organs: homologous organs (=developed from the
same ancestral organ)
Example: development of forelimbs in mammals
Convergent evolution
Starting point: very different ancestors
Organs: analogue (=the same form and function)
Example: wings in animals
Mutation
(random, slow)
adds alleles to the population
Selection
(environment, slow)
subtracts alleles
from the population
Genetic drift
(random, fast)
subtracts alleles from the population
= decreases genetic diversity
Biomes
groups of ecological
communities on earth
vegetation structure is distinctive, not the organisms.
ecological community
all living
organisms in a specific area (during a
certain period of time)
Raunkiaer’s Life forms in plants (1905)
describes the position of buds during adverse conditions
types of raunkiaer’s life forms.
Phanerophytes (trees)
Hemicrytophytes (mainly
grasses)
Therophytes (annuals)
primary successsion
when no soil forming has taken place, the first species/ land use.
secondary succession
the changing of a land use/ vegetatation over time.
Environmental conditions
Abiotic environmental conditions that vary over
time and in space, to which different organisms
respond differently
* IS Variable
* IS NOT consumable
Resources
Abiotic and biotic environmental conditions that vary
over time and in space and are consumed by
organisms.
* ARE Variable
* ARE ALSO consumable
Environmental conditions for animals
- Temperature
- Humidity/relative humidity
- pH
- Salinity (compare with plants)
- Level of a harmful substance
- light (compare with plants!)
ectothermic
cold blooded
endothermic
warm-blooded
Role of temperature with ectothermic organisms
Great influence on metabolic rate, growth and development (Q10 = 2 to 3: a 10
0C change in temperature results in a factor 2 to 3 change in rate of
development)
* lifecycle determined by physiological time
(= product of temperature and time)
(Unlike plants, ectothermic animals can influence their body temperature through behaviour)
physiological time
like AOT40 but with plants, accumulated time they can grow during the year.
do endotherms have accumuated time?
NO ACCUMULATED TEMPERATURE
FOR ENDOTHERMS!!!
Role of temperature with endothermic organisms
- Regulation by internal thermostat
- requires much additional energy
- energy requirement: W = a M 0.75 (a =
constant M = body weight)
energy requirement of animals.
→ Per kg of body weight, the energy
requirement of a large animal is lower.
This is due to a smaller surface/volume ratio
Bergman’s rule
in cold regions you find larger species
or subspecies
Allan’s rule
in cold regions you will find types or subtypes of
closely related species with shorter extremities
Three photosynthetic pathways:
– C3 plants
– C4 plants
– CAM plants
C3 plants
- can use only the C3 cycle
- moderately high photosynthesis capacity
- all plants, especially from cold and temperate
regions
C4 plants
- C4 cycle in specialised cells
- very high photosynthesis capacity; low water consumption
- suboptimal in shade and low temperature.
- Especially grasses in dry, warm regions (savanna)
(savannas)
CAM plants
- at night C4 cycle: stomata open, capturing CO2
- during the day C3 cycle: stomata closed, processing CO2
- very low water consumption, low photosynthesis capacity
- only in succulents, cacti and certain orchids
categories of animals
browsers, intermediate feeders, grazers
Damage and predation: defence
- spines, thorns, armour etc.
- chemical defence
- Escape - fruits, seeds: mast years
- camouflage, aposematism and mimicry (Bates)
- deception and bluff
(Note: predators also use deception!) - mutualism: “the enemy of your enemy is your
friend”, e.g. Ants, aphids and predatory mites
competition
- When the claim of one individual on the
resources is at the expense of the
fitness of another individual - in other words:
- when it leads to density-dependent
fertility (= natality) and mortality - then there is competition
exploitation - competition
what one
organism consumes is not available to
others
interference - competition
monopolisation of resources - territiories
Population
A group of individuals of a single species
Unitary organisms
organisms with a highly determinate form and predictable
development (eg birds, fish, humans)
Modular organisms
Organisms that are built up of modules that can
change shape/function in response to the environment. (e.g. plants,
corals)
Clonal organisms
modular organisms in which the structural units
(modules) also survive independently of other units
Genet
(genetic individual): the product of the zygote, which
consists of many modules and ultimately forms an individual
Ramet
the independent unit of a clonal organism
(e.g. a plant shoot with its own roots)
Populations: counting individuals
How to count?
- Census: total population;
not statistical - Sample: part of the
population; estimation,
statistical - Tagging and recapturing:
indirect, statistica
Populations: counting individuals
Marking and re-capturing
proportion of tagged individuals is representative of the population.
Semelparous
an organism has
offspring only once
Iteroparous
an organism has
offspring several times during its
lifespan
Cohort
all individuals born in
the same period (usually a year)
(also called a generation)
Static life table
Counting the number of individuals of a
certain age group to gain insight into the
population structure
Survival curves
Type I: organisms with high survival at young age and a greater mortality risk in later life
(suitable for K-selected species)
Type II: organisms with steadily decreasing survival and a constant mortality risk
Type III: organisms with a low chance of survival and a high mortality risk at a young age
(suitable for r-selected species)
Dispersal
unfocused, dispersal
of individuals or a part of the
population
types of dispersal
Density-dependent: dispersal
due to an increase in local
population density
Age-dependent: dispersal
depending on the age of the
organism; for example, young
animals often colonise new
areas
Migration
focused and often massive movement of a population
Repeated migration
Multiple return ticket; Daily migration similar to tides or daily
commute between sleeping and foraging sites. But also between habitats, as with
migratory birds.
Migration with return
One return ticket only; birth in habitat A, reaching adulthood in
habitat B and migrating back to habitat A for reproduction (salmon, eel)
One-time migration
one-way only; migration in a single direction
When does exponential growth occur?
When resources are unlimited:
- Maximum natality and minimum mortality
- Growth rate r = intrinsic growth rate (rmax)
Exponential growth
unrestrained growth when resources are unlimited
Logistic growth
feedback on population growth through intraspecific competition for limiting
resources
K
carrying capacity of an area (maximum population size limited by resources
r-selected species
exhibit exponential population growth, individuals have many small
offspring. Environmental conditions cause collapse of the population. r-selected
species are often found in unstable environments.
K-selected species
the population grows towards the carrying capacity and will
fluctuate around the carrying capacity. Individuals have few but relatively large
offspring and invest more in their young. K-selected species are found in stable
environments.
Inteference Competition
populations are limited because individuals physically
exclude each other from resources
Exploitation competition
individuals compete by using resources, but do not exclude
each other physically
Grimes plant strategies:
r/K classification extended for the plant realm
Stress-tolerant species (S)
slow-growing and long-living species that dominate in high-
stress, low-competition environments
Ruderal species (R): similar to r-selected species
fast-growing species, massive
reproduction and short-lived. They dominate in low-stress, high-disturbance
environments.
Competition dominant species (C-
competitors):
similar to K-selected species
large, fast-
growing plants that rapidly absorb
available resources. They dominate in
low stress, low disruption
environments.
True predators
Usually kill their prey immediately after attacking
Consume multiple prey animals over their lifetime
Grazers
Attack multiple/many prey organisms in their lifetime
Consume only part of their prey
Usually do not kill their prey
Parasites
Consume only part of their prey (in this case called a host)
Usually do not kill their prey
Only attack a single prey in their lifetime and are usually heavily dependent on their host
Cyclical patterns
Predators inhibit prey population growth and are dependent on prey
populations for their own population growth.
Grazers’ impact on vegetation structure.
cause changes in vegetation structure. Inactive buds become
active when other growing points are consumed. In this way plants compensate for
damage caused by herbivores
Impact of Plant parasitism
lead to changes in competitiveness and thus vegetation
composition
Graphs and formulae regarding impact of predation on populations
discussed in tutorials,make sure to recap.
predation Functional response Type 1
predation (P) increases with increasing density of prey
(N). The predator has no processing time but will become satiated.
predation Functional response Type 2
predation (P) increases with increasing density of prey
(N). The predator does have processing time and will become satiated.
For example: most large predators catch prey that are too large to swallow at once.
The prey must first be torn into pieces to be able to consume it. They have processing
time, but these predators also become satiated.
Predation
Functional response Type 3
predation (P) increases with increasing density of prey
(N). The predator does have processing time, will become satiated, but will opt for
another prey (switching) if the density of the initial prey becomes too low.
For example: a blackbird searches for earthworms, but switches to other prey if the
density of the earthworms becomes low.
Metapopulations
Local populations have unstable
predator-prey relationships
- have a cyclic
relationship between predator
and prey because the prey can
escape the predator in individual
populations
Local populations have larger fluctuations than the metapopulation.
Larger patches often harbour a population for longer periods of time.
Small patches are more likely to have a temporary population (smaller target for
colonisation and greater chance of extinction)
Most important aspects: lecture 3
Counting by marking and recapturing
- Birth, mortality and population growth
- Semelparity versus iteroparity
- r- and K-selected species
- Dispersal versus migration
- Intraspecific competition inhibits the growth of a population
- Predators and optimal foraging
- Metapopulations and stability of predator-prey relationships
Early succession includes the following aspects:
species richness increases
* heterogeneity increases
* number of niches increases
Late succession includes the following trends:
increasing competition
increasing dominance
decreasing species richness
Intraspecific competition
individuals of the same species compete for or exclude each
other from the use of resources, resulting in reduced growth, survival or fitness.
Interspecific competition
individuals of different species compete for or exclude each
other from the use of resources, resulting in reduced growth, survival or fitness.
Significance of interspecific competition
Interspecific competition is one of the most fundamental processes in ecology and partly
determines the dispersion and success of a species, as well as the evolution of a species.
The result is that interspecific competition is decisive for the species composition of an
ecological community.
Interspecific competition: important observations in the field
Competing species live together on a larger spatial scale, but have clear differences
in distribution on a small scale. Fish live in the same river, but are limited in
dispersion to their own zone that is related to a resource or environmental condition
(temperature).
Species are excluded from areas they could populate if interspecific competition was
not a factor. The fish could also live in the zone ordinarily occupied by another
species, but are kept out by competition.
Interspecific competition: efficiency in using limiting resources
Two diatom species occupy the same fundamental niche, but differ in the efficiency of
using phosphate PO4 and silicate SIO2.
Principle of competitive exclusion (Gause)
In a stable environment, two species can only live together sustainably (coexist) when they
occupy different niches.
If there is no niche differentiation, one competing species will drive the other species out.
Interspecific competition: Lotka-Volterra model
A sort of logistic growth model which takes into account the impact of predators on a population as well as measuring how effectively predators turn prey into predator biomass.
Fundamental niche (without interspecific competition!):
The combination of
conditions and resources that make the occurrence, development and reproduction of
a species possible.
Realised niche
the conditions and resources that make the occurrence , development
and reproduction of a species possible in the presence of other species that limit
survival (interspecific competition).
Character displacement
a morphological adaptation due to competition
to reduce interspecific competition
Mongoose competition
In the presence of large competing
species, the upper jaw of H. javanicus becomes smaller
to exploit an open niche of small prey
(niche differentiation)
character displacement vs. niche differentiation
Character displacement: a morphological adaptation due to competition
to reduce interspecific competition.
Niche differentiation: adaptations of species to a new environment and/or resource
Therefore:
Character displacement is the result of competition (current or in the past)
Niche differentiation can be the result of competition, but not necessarily
Biodiversity index
an index that weighs both species richness and the
distribution of individuals across species (evenness)
two biodiversity indexes and what do they weigh more heavily on ?
simpson - weighs equal distribution
Shamon - weighs species richness
why does high nutrient availability reduce species richness?
Species that can use nutrients efficiently will dominate and outcompete other species.
Explanations of species richness: effects of predation
Predators ensure greater species richness by preventing competitive exclusion between
prey species
Explanations of species richness: effects of parasites
Predators ensure greater plant species richness by preventing competitive exclusion
Explanations of species richness: effects of disturbance
Initial situation: niches overlap substantially with expected competitive exclusion
(equilibrium theory around K)
Disturbance: prevents competitive exclusion due to fluctuations in environmental
conditions (non-equilibrium theory) and ensures that strong competitor species do not
dominate
Abiotic disturbance: wildfires, storms, floods
Biotic disturbance: herbivores, predation
Effects of disturbance on vegetation:
After disturbance (humans and
climate!):
Pioneer vegetation and new
succession to climax vegetation
After intensive grazing:
interspecific competition, strongly
competitive plants are supressed,
grazing-tolerant plants remain
Explanations of species richness: spatial factors (island theory)
Colonisation (distance effect)
The greater the distance from an island to the
mainland, or the smaller the island, the smaller
the chance of colonisation by species.
Extinction (area effect)
The smaller the island, the smaller the population
and the greater the risk of extinction.
Migration effect (I):
As more species are present on an island, fewer new species will
migrate there.
Extinction effect (E):
As more species are present on an island, extinction increases.
how do you experimentally determine a food web?
by caging animals to let only certain species enter.
keystone species
species, which once removed, would lead to the extinction/ destruction of a food web.
3 substystems in a food web
autotrophic
herbivorous
detrivorous
levels in a food web
primary producers
secondary producers
predators
decomposers
what complicates food web naming
it depends on whether you draw all connections and then every species can have multiple names
Residence time
In this case, the time
that energy remains
stored in a pool
(dimension hour day
year)
Turnover rate
Fraction of the pool that
is replaced annually
(dimension hour-1 day-1
year-1)
NPP
net primary production
GPP
gross primary production
formula for NPP
NPP = GPP – R
r is respiration rate
NEP
net ecosystem production
GEP
gross ecosystem production
formula for NEP
NEP = GEP – Re
what is Re
(Ecosystem respiration) = R (autotrophic) + R
(heterotrophic
Primary production (NPP)
is related to:
* latitude (exposure to the sun and length of growing
season, temperature)
* rainfall
* terrestrial or aquatic environment
Secondary production energy
losses in respiration, and dead OM, so it is not an energy cycle, as driver is sunlight, and energy does not go back to the sun
biomass pyramids
are upside down because you need lots of insects to replicate the mass of one wolf.
on what is biomass dependent
Biomass dependent on production, consumption and lifespan
Lindemann’s efficiency
refers to the efficiency of energy through the trophic levels. It is roughly 10%
Terrestrial
environments usually
have …….. variation in
secondary production
large
causes of low consumption efficiency
– Plants defend themselves
– often low density of herbivores
(due to predators and parasites)
-scarce nutrients for plants
often low density of herbivores
(due to predators and parasites)
assimilation efficiency
assimilation/ consumption
assimilated is only what is actually used by the organism. This is not what is excreted.
causes of variation in assimilation efficiency
– C : N in plants: 40 : 1, or more
C : N in animals: 8 : 1
– Plants: poor food quality
production efficiency
production/ assimilation
does not count energy for respiration,
Depending on physiology and life cycle
production efficiency relating to blood temperature
Area/volume ratio plays a role in the production efficiency of warm-
blooded animals
High production efficiency does not necessarily mean high fitness
invertebrates: negative relationship
to size
endothermic animals: positive relationship to size
Decomposition
degradation of organic matter
lignin> hemicellulose>cellulose>soluble sugars
^ decomposition time
microorganisms:
chemical conversion
* fauna: fragmentation
decomposition rates and latitudes
at higher latitudes, cold temperatures ensure slow decomposition and the accumulation of litter.
3 types of forest soils
mull, moder, mor
increasing litter accumulation and decreasing decomposition rates.
from clayey to sandy
what determines the rate of litter decomposition
is determined by microorganisms and soil fauna
* depends on:
– water balance of the soil (humidity and O2 content)
– temperature
– chemical composition soil and DOM
– presence of soil organisms
* determines the availability of nutrients for plants
what is important about the N cycle and whether it is closed or not?
small scale: partly open and partly closed,
large scale: the cycle is closed.
what can you say about peat formation in NL
peat has formed gradually over the years, increasing the elevation level in some areas. Nowadays, peat is oxidised and elevation decreases, resulting in sinking ground.
LOOK AT AGAIN IN ECOLOGY TEXTBOOK
CYCLES AND PRODUCTIVITY
climate change
is important and happens and you know about it. It is unequivocally caused by humans.
ways to manage climate change
mitigation, adaptation, suffering
Direct effects of CO2 increase
- enhanced photosynthesis
- stronger growth of individual plants
- higher NPP of ecosystems
Cause of success of exotics
Enemy release hypothesis
Escape your enemies (predators, parasit
Forms of rarity depend on
- habitat area
- habitat specificity
- population size
Area protection
Species richness
* Abundance
* Species diversity
* Biodiversity
Biodiversity =
= species diversity
= genetic diversity
= diversity in habitat types
→ biological diversity
