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