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Summary Ecology (NWI-BP030)
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Summary of the lectures, lecture slides and tutorials of Ecology with graphs, drawings and diagrams.
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Ecology summaryL1 What is ecology?
Ecology = relationship of organism with its environment
- Distribution and abundance of species
- Interactions between organisms
- Flux of energy and matter
Speciation:
1. Allopatric phase = subpopulations get geographically isolated
2. Reproductive isolation
3. Sympatric phase = subpopulations remeet, natural selection occurs and favours one feature
Allopatric speciation = via geo isolation
Sympatric speciation = via differences in one population at the same site
Proximate explanation = how does it happen
Ultimate explanation = for what purpose (why) does it happen
L2 conditions and resources
Conditions = physiochemical features of the environment
organisms can influence conditions, but don’t consume them
Resources = offered by environment, consumed to grow and reproduce, biotic or abiotic
Photoperiod = length of the period of daylight per daycycle, stimulus for growth/development
Winter: short photoperiod -> suspended development + low metabolic activity = diapause
Spring: increase of photoperiod -> increased development (larva to pop)
Fall: decrease of photoperiod -> increased development (egg to larva)
Ectotherm = can’t regulate own temp, are dependent on environmental temp
Endotherm = can regulate own temp/produce heat -> can also have a low temp/hibernate (mainly
birds/mammals)
Resources for autotrophs (= plants):
- Energy in solar radiation
- Atmospheric CO2
- Minerals in the soil
- Water + dissolved anions
Solar radiation: every plant needs light -> photosynthesis
Too much isn’t great, but doable -> photoinhibition of photosynthesis
Leaf shade = green shade, plants grow better in leaf shade than normal shade
Water:
Avoiders = short life spawn, photosynthetic activity concentrated to periods with water availability
-> desert plants, annual weeds, crops
Tolerators = have long living leaves that transpire slowly -> keep water
,Photosynthetic pathways:
- C3; most plants
- C4; more efficient in CO2 use, and thus water use (best at hot + dry areas)
- CAM; open stomata only at night to absorb CO 2, photosynthesis at daytime
Nutrients:
Mostly N (NO3 NH4) and P (PO4)
Root systems specialise for soil/water availability
Heterotrophs (= herbivores, predators, parasites, scavengers/omnivores)
Different animals have same body composition, different plant (parts) have different composition
-> specialization in herbivores
Defense against predation: specialization + coevolution
- Crypsis = camouflage
- Mimicry = looking like predator
- Aposematism = looking conspicuous, are poisonous
Intraspecific competition = between individuals from the same species
- Interference = fighting for resources; territorial behaviour
o Animals: noise, fight, mark
o Plants = grow wide roots, high branches
- Exploitation = using same resources
Ecological niche = summary of organisms tolerances/needs to live -> where organism lives in habitat
L3 Populations
Natality = fecundity = births (+ population size)
Mortality = deaths (- population size)
Unitary organisms = have predictable development, individuals look the same
Modular organisms = non predictable development, individuals don’t look the same
Counting individuals:
- Counting modules -> physiological individuals
- Molecular techniques -> genetic individuals
Life cycles:
- Iteroparous life cycle = repeated reproduction over life time
- Semelparous life cycle = reproduce only once, followed by death
, Survivorship curves:
Type 1 type 2 type 3
Few offspring x many offspring
Low rate of juvenile loss constant death over aging high loss of juveniles
Mammals birds, small mammals, reptiles fish, invertebrates
Cohort = individuals born around the same time
Cohort life table= survivorship of the members of the cohort over time
Static life table = number of survivors of different ages at one time period
Tutorial 1
Intraspecific competition
K = carrying capacity = max population density
Exponential growth: when no “danger” and uncrowded population,
growth by intrinsic rate of natural increase = r
logistic growth: after logarithmic growth, when population is dense
tutorial 2
Life history = pattern of growth and reproduction over the life time of an organism, result of
evolution
Trade-off: Limited amount of energy; either grow or reproduce, reproduction is costly
r-environment = resource rich, short-lived, colonize quickly and exploit resources
K-environment = crowded populations, persistent, grow instead of reproduce, favouring survival
L4 Communities
Interspecific competition = individual from species A suffers in any way because of exploitation of
resources or interference by individuals from species B
Monoculture = species grows alone, reaches steady population density
Mixture = multiple species grow together
- = one species survives
- = competors can coexist
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