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The Ecosystem (Populations (have certain patterns (distinct growing…
The Ecosystem
Populations
have a size aka density
regulated by density dependent factors and determined by density independent factors
made up of different species
have certain patterns
are prone to fluctuate
small populations are more likely to go extinct due to impacts
environmental stochasticity
demographic stochasticity
can be cyclic
distinct growing patterns
exponential
given by intrinsic rate "r"
grow continuously but not indefinitely
logarithmic
showcase a carrying capacity
when carrying capacity is constant then births and death are equal, however not the case because...
geometric
given my lambda
plants that grow in discrete time periods
growth determined by life history
described in two ways
r-selected or k-selected
stress-tolerant, ruderal, or competitive
have trade-offs
size vs number
size vs growth rate
number vs survival
current vs future
can be patchy and distant
are called metapopulations when linked by dispersal
are equally likely to be colonized and or driven to extinction
e/c is the ratio if >1 then goes towards extinction
Interactions
this course looks at the interspecific interactions between different species
competition
exploitative
interference
results in niches
fundamental might be hindered if a weak species
what is observed is the realized niche
the competitive exclusion principle
showcases how co-existence might not occur
unless the character displacement and or resource partitioning takes place
tends to be asymmetric as one clearly benefits just a little bit more
predation
predators are known as
carnivores
eat other species, thus more nutritious food, however handling time is high and encounter rate low
generalists
herbivores
eat primary producers, thus less nutritious, but handling time is low and encounter rate is high
specialists
predators and preys tend to have a cyclic population that is linked to each other
prey have learned and adapted defense mechanisms
crypsis
morphological features
toxins and poisons
speed
hiding
occur among
parasatism
are evil symbionts and come in different forms
ectoparasites
found outside on the surface of its host
endoparasites
found and inhabit inside of its host
parasitoids
kill their host
hyperparasites
parasites of parasites
micro and macro parasites
pathogens
parasites that spread disease
host parasite model showcase the different variables and the threshold density
beta coefficient is the transmission
m is the recovery and death rate
cannot be too virulent then it cannot presist
characteristics
inhabit only one or two hosts
co-evolved
do not necessarily kill its host
have adapted dispersal mechanisms
Facilitation Interactions
can either be mutualism and or commensalism
tends to be predominant in harsh abiotic and biotic conditions
known as the relative neighbour effect
relationships can either be the following
obligative in which species need these relations to survive
facultative in which species do not need the relationship to survive
can provide two types of benefits
trophic facilitation
habitat facilitation
Biodiversity
communities have events that build them up
this is known as disturbance
succession occurs after
two mechanisms that succession occurs in
primary
secondary
plays a part in promoting diversity
the intermediate hypothesis theory states that during intermediate levels of disturbance biodiversity is high
the Paradox of Plankton showcases how biodiversity is high when the time of environmental changes occurring is equal to the amount of time it takes for a species to dominate
creates the Hutchinson Dynamic Equilibrium Model
all occur apart as a community
community members have specific roles
key stone species
ecosystem engineer
foundation species
showcased in interaction and food webs
postitive and negative direct and or indirect interactions
indirect interactions include
interaction modifications
interaction chains
showcase the different types of competition forms
competitive hierarchy vs network
factors include
richness
evenness
measures
shannon diversity index
spatial scale
alpha
determined by beta
gamma
determined by area and distance
introduces the island biogeography model
two variables
immigration rate
death rate
global
determined
climate
determined by
suns ray's
creates different biomes and distinct latitudes
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prevailing winds
coriolis effect
latitude
regions and geographical area
evolutionary events and history
continental drift theory
beta
the turn over between gamma and alpha diversity
what effects it?
climate
interactions
history
area and distance, for dispersal
Allocation
biomass
inverse among aquatic and terrestrial systems
aquatic upside down triangle
primary producer biomass low because C:N ratio low and defenses low
primary production is the same as terrestrial, that's why they sustain
terrestrial right side up triangle
primary producers make up large biomass
trophics
energy moves up the level and is dependent upon how much energy is in an ecosystem
energy movement dependent upon the size of an ecosystem and the biomass of certain species
phenomenon aka trophic cascades
bottom up effect showcases importance of predators
introduces the ecosystem exploitation theory
keep population in check
explained via log calculations, to showcase biomass and ecosystem type based on predator presence
Impacts
humans have impacted the globe greatly
were in our sixth mass extinction
characteristics include
rapid rate
large amounts of species lost
reasons include
habitat fragementation
due to economic and infrastructure development
solutions might be wildlife bridges
creates
edge effects
biodiversity loss
limits dispersal
over-grazing
interference with biogeochemical cycles
there are two main ones
nitrogen cycle
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carbon cycle
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pollution
invasive species
can be either accidental or deliberate
process: disperse - establish - integrate
dominates and drives to extinction native and endemic species
methods to prevent include
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loss
ecosystem functions and services
enhanced by
includes stability
occur at a large scale