BIOL214 Ecology - james Flashcards
Whats a Life history strategy?
asks questions why?
attempt to explain diversity we see in nature, through natural selection and why its come to be
Characteristics of an organism that then dictate their ability to maintain fitness in an environment (adaption)
allocating resources to what? growth, reproduction, maintenance
but accounts for trade offs when looking at traits
definition
pattern of allocation of resources for maintence, growth and reprodution.
what does life history theory suggest?
attempts to explain the diversity and mechanisms which natural selection has chosen to shape life history traits.
life history traits:
reproductive
-number of offspirng (ocean sunfish)
-timing of reproduction- careful in reproduction or whenever (mass coral spawning)
-sex ratio of offspring- investing more in male or female
(red campion has male and female parts)
life history traits:
Growth related traits
-Size at birth/ size at maturity
(blue whale largest newborn)
-Growth rates (catepillars growth 2-3mm to 30-40mm in weeks)
life history traits:
mortality related traits
-lifespan- grows slowly but last a long time bristlecone pine 4.5k yrs
-mortality schedule- when is a good time to die?
mayfly live most of life as a larvae and live as a few days as adults just to reproducing stage
objectives:
give examples of range of life history stratergies in nature
explain how natural selection, resource allocation and trade offs give rise to variety of life history strategies
how to group organisms based on their life history
Example pieris butterflies
large white and small white
differ in size
both like cabbage family (brassicase family)
2 different life history strategies
small lays 1 egg
and large lays many (gregarious)
small has more subtle markings and large has bright marks and stay together
why?
Large: takes up cabbage plant defences (mustard oils) accumilate in body and thus noxious to predators.
small: doesnt accumilate defences as well so needs to hide.
Darwinian fitness
lifetime reproductive success
selection for traits that equate to optimum darwinian fitness (reproductive success)
example
ocean sunfish:
lives in open ocean therefore doesnt interact with indivduals of other species has a long life so it has a higher chance of encountering others.
Produces high number of eggs to max fertilisation.
limits to optimising fitness
darwinian demon
https://pubmed.ncbi.nlm.nih.gov/24674028/
why is great duckweed a close comparsion?
unbeatable in nature
organism that commences reproduction almost immediately after birth, has a maximum fitness, and lives forever
individual plants do die but because its clonal then the og does exist (lineage)
Great duckweed-
A quantitative analysis (log-log bivariate plot of annual growth in dry biomass versus standing dry body mass of various green algae and land plants) revealed that duckweeds are thus far the most rapidly growing angiosperms in proportion to their body mass. In light of this finding, we discuss the disposable soma and metabolic optimising theories, summarise evidence for and against the proposition that the Lemnoideae (family Araceae) reflect an example of reductive evolution, and argue that, under real-world conditions (environmental constraints and other limitations), ‘Darwin-Wallace Demons’ cannot exist, although the concept remains useful in much the same way that the Hardy-Weinberg law does.
Importance of evolutionary traits and trade offs
whats happened in the past can limit what you can access now.
organsims trying to max success against these constraints, constraint examples:
evolutionary and phylogentic constraints- has evovled a certain way and therefore is stuck in its niche
physical and developmental constraints) allometric constraints-
you cant have a massive body and tiny legs
resource allocation trade offs
(in and between gen)
if parent has had good food and water hten so will the offspring
biotic pressure- other organisms can get in the way
Allometry
is the relation between the size of an organism and aspects of its physiology, morphology, and life history.
Trade offs
a change in one trait might increase but could decrease focus on another trait thus decreasing fitness in another way
Widespread trade offs-
adult size vs offspring number
(walker et al)
shows a negative size between fertilty rate and body size. the bigger the mammal the less offspring.
reproductive allocation vs adult survival-
reproductive effort- allocation of time and resources put into said care
risk of adult mortality relative to juvinile mortailty
low risk- delayed reproductive effort
high risk- invest as much as pos
types of trade offs
-offspring number (quality vs quanitity)
-productive allocation vs adult survival
-reproductive allocation vs offspring survival
sunfish example (mola mola)
not much invested in each egg, chuck out lots of offspring tho
Why is it useful to group species by diversity traits?
-understand the evolution
-understand how they might respond to change
-understand why some species are doing well with human interference
What traits might contriubute to species success?
life history-
behavioural traits-
aggression
adaptability
genetic traits-
evolutionary potential
physiological traits-
metabolism of an organism
morphological traits-
particualr morphilogical traits
outward appearance (camoflage etc)
other
habitat niche
dispersal ability
stress tolerance
Using species LHT to determine what the future might hold
paper example)
https://onlinelibrary.wiley.com/doi/10.1111/ele.12493
Grouping life history strategies
r vs k
Ways of classifying organisms
r- rate in which population can increase (expanding rapidly) mouse
k- carrying capacity, max population (more stable population) elephant
fast slow continuem-
allocation of production vs allocation of surivual
A theory in population ecology that attempts to establish whether environmental conditions favor the maximization of r (the intrinsic rate of natural increase) or of K (the carrying capacity of the environment). When populations can expand without food reserves limiting their growth, then r selection is in control. When food reserves limit population size, K selection takes over, and increase in one genotype must be at the expense of another. Whereas r selection operates in ecological situations where food reserves fluctuate drastically, and species are favored that reproduce rapidly and produce large numbers of offspring. K selection operates in populations that are close to the environmental carrying capacity, and species are favored that reproduce slowly and generate a few offspring that are well adapted to a relatively stable environment
plant life history variaition
J.P Crime
Broadly group plants in this triangle
Give examples of the diverse range of life history strategies observed
in nature
Explain how natural selection, resource allocation and tradeoffs give rise to the
wide diversity of life history strategies.
Contrast the different schemes for grouping organisms based on life
history strategies and explain why such groupings are useful
Modifications of an organism’s
life cycle to maintain fitness in
particular environments
(adaptations)
Age at first reproductive event, Reproductive lifespan and ageing, Number and size of offspring
natural selection (darwinian fitness)
Selection for optimal combinations of life history traits that increase
Darwinian fitness
example- ocean sunfish
resource allocation- reproductive allocation vs offspring survival
example (mola, mola)
lots of offspring to aid survival chance, in open ocean.
trade offs-
Organisms aim to maximise reproductive success given certain constraints
if giving more to one thing will it effect another too much?
correlation between adult size vs offspring number (walker et al, 2008)
schemes of grouping organisms-(surviorship curves)
r vs k (pianka 1970) do enviromental conditions favour r or k specific species?
issues (resnick, 2002) - stability of the habitat (which part is the soil, the forest etc)
adaptive capacity- changing to enviromental stimuli (coat when cold)
migration- dispersal patterns and coloisation of new areas (pollen release)
now turned to age‐structured demographic models mortality patterns as the cause of life-history evolution
other scheme-
grimes life history triangle c, s, r
competitive, stress tolerant, ruderal,
issues (loehle 1988)
In summary, the triangular data representation
scheme distorts data, results in loss of information,
and generates overly restrictive assumptions about
strategic or environmental trade-offs.
grouping organisms by specific traits
fecundity- high vs low
survival- short or long lived
offspring size- large vs small
age at reproductive maturity- young vs old
Species interactions and community assembly (mutualistic interactions)
lo:
Use examples, to describe the key features of mutualistic
(positive) interactions between species
Use examples to argue that mutualistic
(positive) interactions
are important for community assembly
types of interactions
positive vs negative inteactions (is it pos, neg or neutral)
outcome can vary through time and space. One way in the summer another in the winter etc.
test through=experimental manipulation of interaction
positive examples:
pollination
coral reefs
photosynthesis
negative:
cateipillar feeding off plant
types of positive interaction
(symbiosis)
interspecfic interactions (different species)
mutualism- both species gain in fitness
commensalism- one benefits but one is neutral
Types of negative interaction
interspecifc and intraspecifc
competition
predatorism
parasistm
What are mutalisms?(+/+)
a long term, close associated interaction, some cant live without each other.
needs:
net benefits must exceed cost
each partner benefits
Obligate (essential) and falcultative (useful but non esstential)
example?
obligate example: Yucca moths and yucca plants have a reciprocal obligate relationship- the plants cannot make seeds without the yucca moth, and the moth larvae only reach maturity if they eat developing yucca seeds (Pellmyr 2003).
falcultative: specific birds seed disepersal through flight.
commensalisms (+/?)
eating at the same table
long term close associsation where one benefits the isnt effected in anyway
examples:
-sharks and remora/sucker fish. aid movement through the ocean.
-cattle egret
mutualism examples
symbiotic and protective
mycorzial fungi and plants (fungal network)
plants produce carbohydrates (photosynthesis products)
fungal hypae help plant take up nutrients from the soil
(arbsucular and ectomycorzial)
protective mutualism
ants and acacias
how do ants protect the acasis trees, against inverts and mammals
how to experimentally test mutalisms?
palmer and brody (2013)
ant/acacia
manipulated the number of ants on the 4 trees and recorded tree damage (smoked trees)
categories:
control
1/3 ants removed
2/3 removed
all ants removed
once removed can look at how other animals interact with the trees
(elephants, beetles etc)
how does the acacia benefit?
reduced herbivore damage
increased chance of survival
how to ants benefit?
place to live
nutrition from nectur from acacia
Ant plant mutualisms are generally important for protecting plants
against invertebrate herbivory ( Rosumek et al. 2009)
meta-analysis of lots of studies can compare statistically which benefits are most identified across studies.
error bars over dotted line- not significant
other protective mutualisms
(one organisum for another, food for protection
the effect of synbiont density in protective mutualisms
Drew (2021)
https://orcid.org/0000-0002-9604-1821
endophytes in grasses- fungi deter herbivores
We found that the effects of symbiont density on protection and cost are robust across ecological contexts. Density-function relationships did not vary with host type, symbiont localization or transmission mode, nor the method of density manipulation. Together, our results suggest symbiont density can be a key variable determining the costs and benefits of a protective interaction.
how do mutualisms effect how communities are assembled?
Direct effects on mutualisms on -keystone species which entire ecosystems then depend on
examples:
mangrove tree- rhizosphere, roots and other microorganisms- capture atmospheric nitrogen.
effects of mutualisms in reducing the impact of stressors
ant/acacia- enable trees to persist in areas that otherwise would not have trees
(palmer and brody, 2013)
Facillitation
McIntire & Fajardo (2014). Facilitation as a ubiquitous driver of biodiversity.
The New Phytologist.
https://doi.org/10.1111/nph.1247
one species providing another a habitat for it to live in
We show facilitation to be a ubiquitous driver of biodiversity by first noting that all species use resources and thus change the local biotic or abiotic conditions, altering the available multidimensional niches. This can cause a shift in local species composition, which can cause an increase in beta, and sometimes alpha, diversity. We show that these increases are ubiquitous across ecosystems. These positive effects on diversity occur via a broad host of disparate direct and indirect mechanisms. We identify and unify several of these facilitative mechanisms and discuss why it has been easy to underappreciate the importance of facilitation. We show that net positive effects have a long history of being considered ecologically or evolutionarily unstable, and we present recent evidence of its potential stability. Facilitation goes well beyond the common case of stress amelioration and it probably gains importance as community complexity increases. While biodiversity is, in part, created by species exploiting many niches, many niches are available to exploit only because species create them.
an example of facillitation can increase community diversity:
cushion plants facilitate
each cushion plant species- 11 sites the number of plant species in paried design of with and wothout cushion plants.
on average- more cushion plants more other plants.
is the cushion suffering a loss?
competition
not bothered
https://besjournals.onlinelibrary.wiley.com/doi/10.1111/j.1365-2745.2009.01579.x
NMDS ordination indicated that cushions generate species assemblages structurally different from those found in open areas.
mutualisms under climate change?
co-extinction net works
tree diseases:
-ash die back, mild wet winters causing perfect disease breeding ground.
- one of the most common trees in the UK.
Bascompte
et al. (2019). Mutualistic interactions reshuffle the effects of climate change on plants across the tree
of life. Scientific advances. https://doi.org/10.1126/sciadv.aav2539
Extinctions induced by climate change may trigger coextinction cascades—groups of species disappearing as a consequence of the extinction of species they depend on—thus driving many more species to extinction than originally predicted
negative interactions: competition
2 organisms using the same limited resource.
Inter specific and intraspecific
types of inter and intra specific competition
direct competition: fighting or stealing food
indirect competition: plants competitng for soil and light etc.
why is intraspecifc competiton important for determining growth rates in a species?
logistic growth curves:
species introduced=exponential population growth. As the carrying capacity (k) is reached the population growth rate starts to slow.
half of the K is the fastest rate of pop growth
exponential population growth occurs due to?
low intraspecific competition
competition is often density dependence
2 forms, negative density dependance.
as populations increase then indivudals do less well.
driven by increase of competition for resources but also predators and disease
posititve density dependance (allee effect)
individual fitness will increase the population size. (some groups benefit with more individuals around)
example: blood flukes flatworm
how do you measure the strength of competition in nature?
lab: can check how strong the effect of compeition is by removing or adding resources
field:uncontrolled background enviornment but can still add or takeaway
observation: monitor the change of population in time. No manipulation.
what to measure?
population fitness (growth)
competitive effect (suppress a neighnour) and response (ability to tolerate a neighbour)
measuring strength of competition in nature
badgers vs foxes (mesocarnivores)
used randomised badger culls to see if removing badges effected foxes.
results across 4 study areas:
how consistnet are the result?
3/4 areas showed an increase i foxes.
this suggests there is comp and when badgers are removed there are an increase of foxes.
which is more important inter or intra specfifc?
meta-analysis of 35 pairwise plant species, showed competition is common in nature.
intra specific competiton showed more of an impact
ecological niches and competition
fundamental niche and realised riche.
what happens when species compete?
competitive exclusion: local exclusion of a competing species
niche differentation
evolutionary change
in symparty
coexistence
competitive exclusion example
grey squirrels replacing grey squirrel
niche differentation
predictions:
-coexisitng competitors should show niche differentation
-potential competitors with little or not niche change wont co-exist.
example: the grants
different finches that have adapted to reduce competition and get into new niches.
how do species co-exist?
niche differences allow for species to co-exist.
As similae species with similar niches will experience more competition
experiment with 10 plants on annual plants on serpentine soils
monitored community composition with and without niche difference
created a model if there were no differnces.
Species were highest in the community when there was competition.
in absence of niches one species dominated the communities.
apparent competition?
when 2 species have an indirect effect on each other by both being prey for the same predator.
say a hawk who preys on mice and on squirrels. Say theres a rise in squirrels then the mice will be better off as they might eat more squirrels.
14) Disturbance ecology and succession
lo:
Understand distubrance is an important process in maintaining biodiversity
Use example of particular communities to explain process of succession
- community?
- community structure?
- Community assembly?
- Species diversity?
group of interacting organisms
attributes such as number of species, types and relative abundance
study of processes that shape identity and species abundance
the number and abundance of species present in a community defined using:
species richness (S)
species eveness (E)
Measuring community diversity
Simpson index
D or Di
Diversity measure-
species richness and eveness
Shannon wiener index
H or H
What maintains diversity in communities?
mutualism
competition and niche diversification
The importance of disturbance
constant flux not in equillibirum.
Abiotic disturbances
when you look at a community they arent at equillibirum. Constant flux. Disturbance is a temportary change in environment that causes a pronounced ecosystem change.
examples-
*mechanical- boulders rockshore
*phyico/chemical- acid rain
disturbances can be periodic or annual flooding
or can be cercastic
davis and mortiz (2013)
Davis & Moritz (2013). Mechanisms of disturbance. Encyclopediaof Biodiversity (2ndedition). http://dx.doi.org/10.1016/B978-0-12-384719-5.00034-4
paper downloaded
factors shaping overall
Intermediate disturbance hypothesis
(connell 1978)
extremes- Good predators dominate when theres low disturbance intensity. (competitors)
At a contrast few species can tolerate high levels of disturbance.
(stress tolerant pionners)
But when a mix theres a stress tolerant species occur
so a mix of the 2 creates a higher species richness
Sousa (1979)
Boulder experiment
small boulders expected to be moved more often then bigger ones by wave action. Intermediate size boulders which are moved around occasionly but not that often.
Measured the Force used to move a boulder. If a boulder is moved around constantly then dominated by green alga and barnacles. Red algae on intermediate and large.
2 dates in which they collected data
N= number of boulders checked in each force class
intermediate= has the optimised number of species.
Issues to consider:
would this pattern occur in different species groups?
what is the most appropriate disturbance?
how do we best measure this?
2 extreme communities
founder controlled-
competiton is low and disturbance high, community is dominated by things that come in (the founders).
Example grass on chalk land.
As grazers coming in and out frequently its disturbed.
Dominance controlled community-high competiton and therefore disturbance becomes quite rare theres pioneer species but good competitors start to dominate.
example in sand dunes
What happens following disturbance?
Ecological succession:
change in community competiton and structure over time due to disturbance
*Primary succession:
on newly formed geological substrate (community completely lost at start- when glacials retreat the grass under that)
*Secondary succession:
After a forest fire, soil is intact but the distrubance has changed parts.
Example of primary succession
mount st helens
video
stages of succession mount st helens
volcanic eruption-
1) early pioneers, early sucessional species, high nutrient but no big trees, sparse vegetation that likes light (lupin) fixed nitrogen
2) transitional species: competitive start to establish for light etc- 36 years post. some trees and bushes but lots of meadow still.
3) late successional- back to post eruption. Big competitive trees.
Disturbances enhance environmental heterogenty
changing conditions elevate biodiversity. Same forest with gaps in it will equate to smaller and less competitve species filling those niches
Patch or gap dynamics
*small scale- diseased or old trees *felling - allows pioner species
*large scale- storm
*extreme- volcano
opening up the canopy
Disturbance (old trees falling over in forest, gaps in canopy cover)+
+succession (gaps colonised by pioneer plants)
= heterogenous (vroader range of habitats for plants and associated organisms
gap dynamics and forest diversity
bongers et al
tree diversity in ghana
disturbance index % of pioneer tree species present.
fewer pionners fewer disturbance index.
plots showed reduced species where theres extremes and the most in the middle.
*applies to tropical forests, but disturbance contributes little to tree diversity
Secondary succession example:
Bosc & Pauw(2019). Increasing importance of niche versus neutral processes in the assembly of plant–herbivore networks during succession. Oecologia. https://doi.org/10.1007/s00442-020-04740-7
fire adapted communities:
processes occuring early stochastic processes and late in sucession (niche based).
looked at fynbos, post fire succession on plant species and herbivorous arthropods.
number of interacting species were sampled at different quadrat level.
how this community built up over time
plant increase over time, but at overtime theres a large jump up when habitat becomes more liveable.
Looked at specalised interactions, more specalist species changes in a positive manner.
thus generalist species at the start and more specalist further on.
(niche differentation)
disturbance ecology- effects of exploitative interactions
distinguish between different types of exploitative interactions
use examples to illistrate how these interactions can cause disturbance thus causing diversity.
an interaction where there one member benefits and the other exploited
types of predation
i=d
ii=b
iii=c
iiii=a
generalist and specialist type of interactions
the impact of rhese interactions on communities depends partly on the level of specalism of the interaction.
for example snails are fairly generalsit with what they eat. But the large white capitillar are specalised on cabbage family.
how to measure the strength of interactions?
what measuring?
lab
field
obvs
what to measure?
population or individual fitness
compare fitness before or after manipulation
resistance or tolerance mechanisms
experimental test on different herbivores on grassland test
allan and crawley (2011)
looks at insect and molluscs exclusion and the interactions between them.
Using insectersides etc to create exclusion in fenced and unfenced areas and looked for 14 years exclusion in factorial design.
data showed:
describe the effect of insects and molluscs on plant species richness.
describe the effect of insects and molluscs on plant species richness.
species richness is greater when insects are present in grassland but reduces biomass, independent of molluscs.
Molluscs tend to have a slight negative effect on species richness and increase biomass overall.
the effect of molluscs are dependent when insects are present or absent, but biomass bigger overall.
how exploitative interactions increase community complexity
https://www.science.org/doi/10.1126/science.1214915
pocock et al: ecological network
sampled from one organic farm.
Detail the different interactions that are occuring.
(example inverts on an organic farm, herbivory, parasitism, leaf miners, rodents feeding on seeds)
lots of interactions taking place, between plants and inverts.
adding negative interactions- the interactions become more complex.
how herbivores, predators and parasites can maintain species diversity through disturbance?
limiting population growth of hihgly competitive or widespread organisms.
enemy release ‘experiments’
hoffmann (1998)
prickly pear cactus- invasive in australia and south africa but not in USA.
why?
cactus moth and scale insect control growth in the USA
introducing enemies in australia worked but variable in south africa.
studies show- naive enemies might ignore introduced organisms because they dont know what it is.
they dont have the correct signals to identify
importance of coevolved predators
specialist herbivore outbreaks examples?
predator/prey dynamic
important disturbance in ecosystem
lynx-rabbit (predator prey)
specalised herbivores:
cinnabar moth+ragwort
cyclical dynamic where more of one equals less of another the next year
outbreak of specialist herbivores:
Kunegel-Lion & Lewis (2020). Factors governing outbreak dynamics in a forest intensively managed for mountain pine beetle.
https://www.nature.com/articles/s41598-020-63388-8
outbreak of specalist herbivores
lodgepole pine vs mountain pile beetle.
*Endemic phase at the start:
a few beetles around that are attacking the old trees.
*Epidemic phase- go for healthier trees.
*peak infestation
*post-endemic phase- resistant trees remain and others die- run out of host material.
then other trees would thrive during this time
loss of keystone organisms is functional of an ecosystem
wolves to yellowstone national park
had distrubiton of herbivores around the park. Allowed other species to come back to the aprk
dobson, 2016
raster et al. (2020)
sea otter population collapse in 1990’s
no otters=large sea urchins=higher reading (bioerosion)
https://pubmed.ncbi.nlm.nih.gov/32913100/
in the aleutian archipelago:
kelp forms large sturctures on the sea floor and the main food source for sea erchins.
sea otter decline due to killer whales, lose of sea lions.
thus this had an impact on the sea urchin grazing intensity.
rasher et al 2020
Bioerosion rate and sea urchin mass correlated.
and rising sea surface temp determine kelp feeding.
landscape-level diversity and refuges from exploitation.
refuges from exploitation-* enemy-free space*=habitat heterogeneity.
spatial and temporal examples of refuges: cant get in
physical location
habitat quality
predator cycles
refuges from exploitation
example
kohl et al (2018)
gps radio collar data from female elf and wolves in yellowstone
estimated time spent by elf and wolves in different locations through time.
predicted kill occurence
openess
kill density
wolf density
wolf density tends to be linked to open areas where kill density is higher on the elk.
the janzen-connell hypothesis
developed for tropical forest ecosystems and why they are so diverse.
We found strong, overcompensating mortality driven by fungal pathogens, causing 90% (shadehouse) or 100% (field) mortality within 4 weeks of germination, and generating a negative relationship between initial and final seedling densities. Fungicide treatment led to much lower, density-independent, mortality. Overcompensating mortality was extremely rapid, and could be missed without detailed monitoring. Such dynamics may prevent dead trees from being replaced by conspecifics, promoting coexistence as envisioned by the Janzen-Connell hypothesis.
2010 Blackwell Publishing Ltd/
100’s species per hectare
exploitative interactions could be the cause
invertebrate herbivores/ pathogens thought to be important in tropical forests.
species-specific enemies make the area around a parent tree inhositable for offspirng (conspecifics)
negative species dependance
Disturbance: exploitative interactions
-distinguish between the different types of exploitattive interactions
-use examples to illustrate how exploitative interactions act as a form of disturbance to influence community diversity
Disturbance ecology and conservation:
use examples to explain anthropogenic disturbance might impact ecosystems
describe the impacts of too much or too little disturbance
explain the difference between rewilding and active conservation management
natural ecosystem processes vs artifical
natural: biotic and abiotic
artifical (uncertain how organisms will respond): pollution, urban environments
common types of anthropogenic disturbances (human caused)
organisms dont know how to react
habitat destruction, fragmentation, degradation, invasive species introduction, climate change
examples of anthropogenic disturbance (where organisms are less adapted)
Davies , T.W. et al. (2020). Biologically important artificial light at night on the seafloor. Scientific
reports, 10, pp. 12545 . https://doi.org/10.1038/s41598 020 69461 6
artifical light (light pollution)
across plymouth sound/ tamar estuary
Using a combination of mapping, and radiative transfer modelling utilising in situ measurements of optical seawater properties, we quantified artificial light exposure at the sea surface, beneath the sea surface
76% of the three-dimensional seafloor area was exposed
green wavelengths was high
mountain paths and roads:
-trampling of slow growing alpine plants
-species being brought up to mountain areas
-spread of disturbance-adapted mountain plants (alpine rock cress).
common plant pf disturbed rocky areas. It thrives quite well in the disturbance.
evoultionary history: species can be well adapted to the event (plants and fires)
when disturbance starts occur outside of their evolutionary history.
novel types/intensity: reduced fitness as they are not adapted to the amount things are happening
natural not anthropogenic examples:
volcanos
earthquakes
natural disturbances becoming more frequent due to human influence:
acres of land being effected by wildfire in the USA.
forest fires
intermediate level of disturbance example: reducing levels of human disturbance
noise pollution in the ocean
takeaway people- wildlife returns (seen during covid)
Young coral being effected by noise pollution
at the moment many ecosystems are being disturbed too much.
impacts of too much disturbance
example (climate change)
Maxwell, S.L. et al. (2019). Conservation implications of ecological responses to extreme weather
and climate events. Diversity & distributions, 25, pp.613 625. https://doi.org/10.1111/ddi.12878
looked at 19 different responses (behaviour etc) of species to extreme events (drought, fire, storms)
what were the effects of these extreme responses on a number of organism groups
some animals arent as well represented.
mostly neg responses.
short term responses
Extreme weather and climate events have profound implications for species and ecosystem management. We discuss current conceptual challenges associated with incorporating extreme events into conservation planning efforts, which include how to quantify species sensitivity and adaptive capacity to extreme events, how to account for interactions between extreme events and other stressors, and how to maximize adaptive capacity to more frequent and intense extreme events.
thrush and dayton
impacts of ocean sea floor on soft sediment communties through trawlling and dredging
https://www.jstor.org/stable/3069270
impact of too much disturbance, too much fishing causes decline in heterogeneity and things cant repopulate quickly enough due to overfishing.
not enough disturbance:
-farming in monocultures
-undergrazing (abandonment)
-loss of keystone herbivores
-lack of complexity in urban enviornments
Lundgren, E.J. et al. (2017). Introduced megafauna are rewilding the Anthropocene. Ecography , 41
loss of keystone herbivores
(megafauna)
native richness is low in many regions of megafauna
consequence of late pleistocene extinctions (human driven)
megafauna have been introduced across the world but alot arent native but for agricultural reasons etc
heterogeneous environments strike a balance between succession and disturbance
finding the intermediate
whats too much?
creating a middle between
high competition (only sucession thus no grazing) vs low competiton (only disturbance with constant grazing)
looking for that intermediate spot
ongoing research topics:
*interactions between disturbance types
*ecological tipping points
*unified framework to study disturbances
*restoring ecosystems through rewilding
interactions between disturbance types: the effect of one type alone is different when in combination with another
examples:
https://academic.oup.com/bioscience/article/70/10/854/5901988
-degraded habitat being more susceptible to invasive species
-extreme climate and invasive species
mountain pine beetle:
large scale tree death
humans- salvage logging or new samplings. But they’re all the same age and once reaching maturity are attacked again by beetles and cycle contiues
ecological tipping points
where disturbance has an impact on a communites structure (community state)
change in a community dramatically (one state to another)
example: algal blooms- clear water to green algal blooms- nutrient inflow from agriculture
hard to switch back to the og slate
dry degraded grassland turning to desert
a unifying framework for understanding future impacts
what is a disturbance?
https://www.frontiersin.org/articles/10.3389/fevo.2021.588940/full
graham et al (2021)
used socials to to devise cohesive stat for studying disturbance.
distinguish between:
disturbance drivers: what causes the change
distrubance impacts: what happens after
restoring ecosystems through rewilding
beavers in plymouth
rewilding (increase biodiversity and ecosystem resilliance, uses wildlife-
active habitat management (human involvement) is to protect a particular species that is important to us
can rewilding replace habitat management
chalk grasslands (calcareous)
would this environment exist in a rewilding concept?
can the oceans be rewild?
new megafauna dont need to be reintroduced (human disturbance is biggest issue)
Sanabria Fernandez et al. (2019). Marine protected areas are more effective but less
reliable in protecting fish biomass than fish diversity Marine Pollution bulletin.
https://doi.org/10.1016/j.marpolbul.2019.04.015
https://www.researchgate.net/publication/332524620_Marine_protected_areas_are_more_effective_but_less_reliable_in_protecting_fish_biomass_than_fish_diversity
