Module 4 Flashcards
What is biodiversity
It refers to the full range of organisms on earth and their interactions
Why is biodiversity good for us (benefits of biodiversity)
Having a good biodiversity enables a healthy ecosystem. Healthy ecosystems allow for a lot of benefits
Biodiversity is key for human survival, wellbeing and economic propserity
They provide:
Sources of food
Drug derivations
Water
Pollination
Pest and disease control
Recreational Use
Cultural Significance
Rat material provision
Soil fertility
Nutrient cycling
What % of Aus is for grazing in modified pastures and cropping
13%
What is the order of crop production area in a decreasing order
Wheat, barley, canola, cotton, sugar cane
What is the order of livestock numbers in a decreasing order
Poultry, sheep, cattle
What are ecosystems
Ecosystems are communities of living organisms (plants, animals, and microorganisms) interacting with one another and with their physical environment (such as air, water, and soil). This interaction forms a complex network of energy flow and nutrient cycling that sustains life within a given area.
(typically includes a biotic and abiotic factor)
Why are our ecosystems good for us
They are the basis of life - they provide habitat, promote food chains and webs, and control ecological cycles and processes
Explore Australia’s biodiversity
320 500 invertebrate species
25000 vascular plant species
243 frog species
750 000 fungi species
5000 nonvascular plant species
830 bird species
390 mammal species
950 reptile species
160 000 single - celled species
5000 fish species
What has been the trend in Aus’s biodiversity?
It has been threatened in the past decades, and there is an increased number of animals considered endangered
What conservation responses would allow Aus threatened species to benefit from the most
Prevention of habitat loss
Getting rid of invasive species
Control of fires
Mitigating climate change
Manging pollution
Preventing overexploitation
What is natural capital
This is the world’s stocks of natural assets - resources and ecosystems which provide humans w/ essential g+s
Explain the case study on the Victorian highlands
Basically in the Vic highlands, the Headbeater’s possumw as under threat due to logging, causing them to be listed as endangered
Logging in Vic highlands thus poses a massive risk to habitat loss of other species as well. Logging here is normally to sell the timber
However, money gained fro harvesting timber is actually significantly outweighed by other industries –> if this is the case, then why do we continue doing it?
As a result, we need to think holisitcally on nature-based solutions and diverse teams needed to make progress on habitat destruction
What is the function of the System of Aus Environmental Economic Accounts (SEEA)
Takes human inputs, productions and benefits and same ecosystem services into account when calculating the GDP
What are ecologists meant to do for the earth
Act as ‘doctors’ for the earth
They record observations in biodiviersity –> diagnose problems, manage risk and monitor change –> prescribe a treamtnet/remediation and restoration for the problem –> advocate for ecosystem health
What was Scientists’ warning to humanity in 2017
There is a decrease in freshwater resources, increased co2 emissions and temp changes, increased population, decreased forest area and vertebrate species abundance
What was Scientists’ warning to humanity in 2021
Increased population, increased energy consumption, decreased ice mass, increased GHG emissions and CO2 emissions
What is ecosystem collapse
Basically when disruption of ecosystems lead to irreversible collapse of the ecosystem, especially if defining features and functions of ecosystem are lost
How many AUs ecosystems have been reported to show signs of collapse
19
What are some collapse pofiles (explain whta they look like)
Abrupt (immedaite drop in population)
Stepped (gradual ‘step-like’ drops in population)
Fluctuations (constant jumps and drops in eco population)
Smooth (gradual decrease like an exponential curve)
What are ‘presses’ in ecosystem collapse
These are gradual/ongoing changes in enviro which cause ecosystem collapse
What are ‘pulses’ in ecosystem collapse
These are sudden changes in enviro which cause ecosystem collapse
What is morphology
This refers to the physical structure of an organism including shape, size and anatomical features
How can morphology influence behaviour? Give examples.
These physical traits are normally influencing or adapted to specific behaviours and physiological processes
I.e. streamlined body of a fish allows for the behaviour of swimmin
The ability to have wings allow for the behaviour of flying
Carnivores have different gut floras –> causes them to want to consume meat
What is physiology
Refers to the internal biological processes that keeps an animal alive, such as metabolism, respiration etc
How can physiology influence behaviour? Give examples.
The presence of fast twitch muscle fibres in cheetahs allow them to have a predatory behaviour when it comes to hunting animals
What is behaviour
Behaviour is an action or reaction of animals in response to various stimuli, and is normally shaped by the animals’ morphology and physiology
Give an example of behaviour
Being able to fly, or predators stalking prey (enabled by morpholpogical trait of sharp claws or physiological trait of fast reflexes)
What is coping mechanism composed of
Coping mechanism = behaviour + morphology + physiology
How can behaviour be related to the abiotic environment?
Behaviour might be in response to the abiotic environment
For example, a lizard might try cooling its feet on a hot desert sand by constantly alternating which feet they lift up –> drives behaviour of lifting feet etc
How can behaviour be related to a biotic environment
Behaviour might be in response to other organisms
I.e. being scared of being hunted –> hiding/escaping/defending/foraging etc
What is fitness
Fitness refers to an animals ability to reproduce or contribute to the genepool of offsprings
An individuals relative contribution to the next generations gene pool
Can behaviour affect fitness? What experiment?
Insect herbivores consume vegatitive parts of plants (e.g. leaves)
Insects pollinate ~2/3 of all plants, often w/ food reward (e.g. nectar
Does eating diff quality resources influence fitness?
Does food quality affec butterfly reproductive success? –> foraging on high quality food has a fitness advantage?
What did the experiment on behaviour and fitness find?
There is no significant impact of adult nectar quality on no. of eggs laid, however there was a significant impact of larval diet quality on the no. of eggs laid
Thus, concluded that behaviour affects fitness, together w/ morphology and physiology. Thus, many behaviours are adaptive
What is the ecological significance of behaviour
Behaviour acts as a link between individuals and their environment
Behaviour affects demographics (population level etc)
Affects interactions between diff species
What is the evolutionary significance of behaviour
Behaviour has some genetic basis (nature vs nurture)
Behaviour affects fitness
Behaviour can be selected when benefits > costs
Explain how animals may try to obtain their food
Ambush predators ( good camouflage to catch food)
Active predators (agile and quick –> easier to catch food)
What influences animals foraging strategies
What they eat
Diet breadth (specialist –> generalist)
How they get the food (ambush vs active)
Foragining strategies AREN’T RANDOM A
What is the Optimal Foraging Theory
Suggests that an animal wants to maximise their rate of food intake
But, they must make trade offs when deciding how and where to forage. Trade offs include energy expenditure, time, predation risk and food availability
What is the Giving Up Density
This refers to the remaining quantity of food when a forager will decide to leave a food patch
What is the Marginal value theorem
This is where animals decide when to leave a resource patch and move to another to optimise their foraging efficiency
Modelled when to leave a food patch in a depleting environment, and predicts that foragers should leave a food patch when capture/harvest rate of a patch is less than the average capture/harvest rate of all of the patches
What are some anti-predator strategies?
Staying in a group
Acting costly
Be costly
Stick to foraging in known/safe areas
Hide
Run away
What are some costs to the anti predator strategies
Group –> more competition for existing food
Feeding near safe places –> missed opportunities for potentially more plentiful feeding places
Is reproductive behaviour random?
No
What are the two main behaviours relevant to sexual reproduction
Male-male competition
Female choice (sexual selection)
What are the two types of sexual selection
Intrasexual selection
Intersexual selection
What is intrasexual selection
This refers to male-male competition
What is intersexual selection
Refers to mate choice (often by the female)
Why do peacocks have fancy tails?
It is confusing because they do have high costs of maintaining the tail, but the benefit is that it increases access to mate, which is ultimately good
Explain the benefits and costs of parental care
Benefits = increased survival and growth of offspring = greater fitness
Costs = missed opportunities (i.e. less food)
Justify why behaviour isn’t something only animals do
Slime moulds normally move to more nutrient-dense environments, even though they arent animals and dont have brains
Plants have diff behaviours at different times as well (leaves and stems grow towards light, and the roots grow along chemical gradients)
What is a group
A group refers to multiple organisms who may be of same or different species occupying a common space. However, they don’t necessarily have to be interacting with one another
What is a population
A population refers to a number of organisms of the same species occupying a common space/geographical region.
Populations could move around
Why is knowing about populations important (importrance of population biology)
Form understanding of ecology, evolution, conservation and management
Understand temporal dynamics of populations (how they change over time), understand spatial dynamics of populations (where are these populations across Aus), looking at how populations are limited by spatial and temporal distributions to help us understand them a bit more
Explain variables affecting changes in population size
Births
Deaths
immigration (coming in)
Emigration (going out)
Growth
Age of maturity
Sex ratio
What are the conditions of population growth in closed systems
Only affected by births and deaths
Population growth = change in no. of individuals over time
WHat is the formula for popuulation growth in closed systems
Nt+1 = Nt + Births - deaths
Explain the role of birth and death rates in determining population growth
Fundamental to population growth. Births are additions to populations whereas deaths result in drops in population
What is exponential growth
Populations grow faster as they get bigger
What are the different dynamics of population growth
Discrete, continuous
What is discrete population growth? Why does it occur?
Reproduction occurs periodically (i.e. only spring) –> population graph looks disjointed, goes up and then drops and then repeats but overall up
What is continuous population growth? Why does it occur?
It is a smooth curve up or down or straight. Occurs because reproduction might occur year round
Why do we rarely see exponential growth? What do we see instead?
We see a logistic curve. this is because often population growth is resource limited –> can’t keep growing such as that of an exponential growth
What is the carrying capacity
The maximum population an environment has the ability to provide for (considering enviro restrictions) 0 growth stops at carrying capacity
How can we estimate birth rate
Histology of reproductive organs
Capture/counting of fertilised gametes
Counting of newly born individuals
How can we estimate death rates
Challenging as we can’t know if an animal is dead unless we see it appen or sample entire population. Common methods:
Tagging - check o how many of the tagged are alive and then assume
What are the variables at play for population growth in open systems
Influenced by birth, death, immigrants, emigrants
How can we estimate population growth in open systems
Tagging and recapture (physical, acoustic, gps, radiotelemetry), genetics, can also use citizen science
Explain how mark-release-recapture works
MRR estimates total population using sample proportions
Assumes various things: closed population (no immigration/emigration), all individuals equally likely to be marked, marked individuals don’t lose their mark
Explain the formula for mark-release-recapture
Number marked / population size = number of marked recaptures / number of recaptures total
rearrange
WHat is a spatially structured model
model used to study enviro systems that incorporate effects of spatial variation and organisation –> takes into acount that interactions, movement, processes vary depend on geographical / spatial arragnement rather than an even spread approoach
Metapopulations are local populations but individuals move, and demographics vary spatially
How can we estimate growth and age of animals or plants
Trees - tree rings
Perennial plants - rings in tap roots
Mammals - teeth
Fish - otoliths (rings in teeth and teeth wear)
What is an age/stage model
Involves treating all members of a population with regard to their age and stage of life (especially as that influences their fecundity and survival)
Life tables show survivorship probability at each age. Long term studies is jet to understanding population dynamics
Involves splitting populations into different age groups / stages and seeing the spread
WHat are the principles of a Population Viability Analysis? WHat does it aim to do/model
PVA is a tool to model population dynamics over time, and uses basic population data. It allows us to model:
How changes to ecosystem will affect % of popultion surviving, how these changes interact w/ one another, and how the changes ineract during one or many bad years (e.g drought)
Ultimately allows to predict population dynamics in the future, and predict impact of changes in enviro
What is the key info required for a population viability analysis
Population size/ carrying capacity
Fecundity (% of giving birth)
Mortality
Inter-annual variation in parameters
What is extinction
The loss of all populations of a species
What could result in extinction
Genetic stochasticity (small populations)
Demographic stochasticity (random nature of births and deaths)
Environmental stochasticity (variability)
Catastrophes (cyclones, epidemics)
Human impacts (habitat loss, fragmentation, pollution, hunting, pest spcies, climate change etc)
What is the biological species concept? WHat are the problems?
Defining a population as a group of organisms which reproduce with one another to form viable offspring
However, the problem is that there is often cross - species breeding (hybridisation): i.e. a lion and a tiger (liger)
What are some other species concepts
Phylogenetic species concept
Ecological species concept
Morphological species concept
What is the phylogenetic species concept
Defines a species as the smallest group of organisms that share a common ancestor and can be distinguished from other groups based on unique characteristics (typically genetic or morphological traits)
What is the ecological species concept
A species is defined as a group of organisms who play a similar role in ecology
Defines a species as a group of organisms that occupy a distinct ecological niche - defined by the unique role they play in the ecosystem, and how it interacts with the environment
What is the morphological species concept
A species is defined as a set of organisms who have a similar/same physical structure
Defines species based on overall similarity in what a species looks like
What is the species problem
It is hard to define what a species is
Describes the difficulty/debate in biology about how to define and distinguish species
Do species matter? If they do, why?
Yes, they do matter for various reasons:
Idea of species is actually real for most organisms
We need a common way to describe a group of animals –> easier to refer to rather than description of characteristics
Underpins local, state and international conservation efforts
Explain the importance of spcies through case studies w/ dingoes
Is it an own species or a subspecies of dogs?
Differs in morphology, ecology, behaviour and genetics w/ dogs
However, they can interbreed w/ domestic dogs
The determination of the species type will allow for management and conservation based on definition of dingo as a separate species
How do we count number of species in practice?
We need to define an area to do our count first, and then do some counting
What is the method for counting species which are large
Count one by one, if they are visible
What is the method for counting species which are small
Traps for small/shy species e.g. insects
Cameras/remote sensors
What is species richness
Simple count of how many species there are
What is species diversity
Measure of the number of species (i.e. species richness) and the number of individuals of these species broguht together into a single index
Why do we need species diversity indexes?
Because lets say a sample from enviro A has 91 individuals of one species, and single individual for each remaining 9 species, whereas sample from enviro B has 10 individuals from 10 species
Although both have same species richness, the enviro B has increased species diversity as numbers are more even –> takes this into account in SDI
What are species diversity indexes? Common ones and how to calc?
Indexes used to compare the species diversity of two or more samples
Berger-Parker Index : 1-Nmax / N, whree N is no. of individuals in the sample, and N max is no. of most abundant species
What are the different types of diversity
Alpha, beta and gamma
What is alpha diversity
Number of species within a particular area or habitat (diversity within habitat)
What is beta diversity
Difference in species between areas or habitats (i.e. compared to other ecosystems)
(diversity between habitats)
What is gamma diversity
Number of species from all areas or habitats combined (regional diversity)
(regional or landscape diversity)
How many species of mammals are there in NSW
~110
How many species of mammals are in Aus
397
How many species of mammals are there in the world
~6495
How many species are there in the world?
1.5-1.82 million have been described w/ name according to current texts
How can we estimate the no. of species yet to be discovered?
extrapolate from current rates of diversity
How many species were there until 2017, and how many after? WHy?
Until 2017 10-100 million species, but changed in 2017 with recognition of diversity of bacteria
Larsen et al estimated 2.238 billion species with using estimates of arthropods and their mites and arasites etc, and considering bacteria asw
What are autotrophs
These are organisms which can synthesise energy/food by itself
What are heterotrophs
These organisms most consume other organisms for energy/food
What are trophic levels
Refer to hierarchical positions of organisms within a food chain or food web
Each trophic level represents a step in the flow of energy from primary producers to top predators
Organisms are grouped in these levels based on feeding relationships, and energy is transferred from one level to the next through consumption
How does energy flow within an ecosystem
Energy enters system through photosynthesis and flows through diff organisms via food chain or food webs
What is a curious observation of energy flow in an ecosystem
As the energy flows up trophic levels, there seems to be energy loss to a certain extent
Describe what food chains and food webs are
They are a visual representation of the flow of energy/food in an ecosystem
Are food chains short or long?
They are normally observed to be short
Why are food chains short?
Because of the loss of energy through trophic levels
Explain the energy hypothesis
Energy loss between trophic levels due to heat loss shortens the food chain
Predicts that high productivity ecosystems should have longer chains (high productivity = high rate of primary production –> efficient conversion of energy)
What is the experimental evidence for the energy hypothesis
Jenkins et al manipulated leaf litter in hollows to have high, medium or low
Results suggest that a higher production occurred through leaf litter, reulting in greater number of species and trophic links
Explain the dynamic stability hypothesis
Longer food chains are less stable because fluctuations at low trophic levels magnify at high levels –> top predators likely to go extinct –> shorten the food chain
Explain the proof for the dynamic stability hypothesis
Jenkins 1992 observed that mosquito populations decreased due to rain –> significant impact on food chain length
Thus, long food chains are unsable because the stability of the enviro are reliable enough to maintain good chains w/ more than 5-6 links
What are the different types of ecological interactions
Mutualism
Ammensalism
Commensalism
Competition
Predation
No Interaction
What is mutualism (in terms of +, 0, - for organisms)
This is where two different organisms benefit from the interaction(+,+)
What is competition (in terms of +, 0, - for organisms)
It is when two diff species compete for certain resources –> both species lose out due to loss of energy despite there being a ‘winner’ (-,-)
What is predation (in terms of +, 0, - for organisms)
When one pecies hunts and kills and consumes another organism (+,-)
What is commensalism (in terms of +, 0, - for organisms)
When one species benefits from an interaction whilst the other is neither helped or harmed (+,0)
What is ammensalism (in terms of +, 0, - for organisms)
WHen one species is inhibited/harmed whilst the other is unaffected(-,0)
What is no interaction (in terms of +, 0, - for organisms)
(0,0)
WHat is obligate mutualism
Symbiosis; partners can only survive together
What is facilitative mutualism
Partners gain benefit from associating, but can survive on their own
What is interspecific species competition
Competition between different species
What is intraspecific species competition
Competition within species
Link ecological interactions to the flow of energy through trophic levels using herbivory as an example
Yes
What are communities
Two or more species that interact with each other as an ecological unit which occur together in space and time
Wha are assemblages
Less well defined, but a group of species that live together, with no assumptions made about how or whether they interact with one another
Describe communities over space (spatial changes in community)
There will be a different spatial distribution of communities, depending on various factors like; altitude, climate, soil type
There will be diff vegatiation comunities even in a small scale environment
Describe communtiies over time (temporal changes in community(
Stable communities maintain consistent species richness and compositon, however change in species composition is normal
Change over time driven by local colonisations and extinctions of species
What is succession
Describes process of gradual change in structure and composition of a biological community over time, following a disturbance or creation of a new habitat
Involves stages thrugh which ecosystems progress as species colonise, establish and interact
(i.e. describes how old biological communities are succeeded by the newer ones)
Early ideas related to forests : tree falls down creating gap for lihght –> small plants sensitivity to light grow –> cycle continues for tress to grow
Light is unsuitable for certain species creating high quality enviro for some whilst having a negative effect on others
Explain process of succession in terms of actual plant species
ANnual plants –> perennial plants and grasses –> shrubs –> softwood trees - pines –> hardwood trees
What are pioneer species
Consist of a variety of annual plants (these describe the ‘beginning’ species)
They typically grow in the sun, fix nitrogen, good at dispersal, have small seeds, grow rapidly, have short generation time, and are poor competititors
What are climax species
Consists of more developed plants (i.e. trees)
They typically are shade tolerant, long lived and have slow growth (bc of less sunlight). They also are good competitors
What are the types of succession
Primary and secondary succession
What is primary succession
Succession which occurs in a bare area without soil (e.g. sand dune, bare rock)
Beginning of ecological succession where pioneer species colonise an uninhabited site, usually occurring in enviro devoid of vegetation and other organisms
What is secondary succession
Succession is a process started by a prior disturbance (i.e. a forest fire, hurricane), that reduces an established ecosyste to a smaller population
What are the 3 models of succession
Facilitation, inhibition, tolerance
What is facilitation
Argues that we need pioneers first, and then climax species, as colonisers make it better for climax species –> early arriving species make enviro more favourable for later species
What is tolerance
Neither positive nor negative interactions between early and late species
What is inhibition
Traits of the early species make it hard for later species (i.e. by taking up the resources) –> inhibits later species growth
What is resilience
How long before a community returns to an “equilibrium” / “normal” state after a disturbance
However, what criteria do we have for determining pre and post disturbance conditions?
Ultimately describes the ability to bounce back to a prior state, and normally depends on scale of disturbance as well
What is a disturbamce
A disturbance is a temporary event or process that disrupts the structure, composition or functioning of an ecosystem
Examples include fires, storms, volcanic eruptions, droughts, pollution etc
What is the importance of a disturbance in ecology
Disturbances drive species richness and community composition through ‘resetting’ the climate, which removes some climax species to allow pioneer growth. If disturbances are low, its easy to get to climax community, which is opposite to high rate of disturbances causing basically no species to form
It is important to have a moderate disturbance. This patchy mosaic of disturbance creates highest diversity
What is the intermediate disturbance hypothesis
A patchy mosaic of disturbance creates highest diversity (i.e. we only want some disturbance, not a lot)
What are ecosystems
Community of living organisms considered in conjunction with the abiotic components of their environments, all interacting as a system
What are biogeochemical cycles? What are some examples?
Energy flows thorugh the biosphere
Examples include water, nitrogen, carbon and phosphorus cycle
Explain the water cycle
Look at diagram
~97% of water is oceans
Process of convection, precipitation, transpiration and respiration all move water around the cycle
~3% of water is relatively inaccessible, in icecaps, glaciers and as deep groundwater
Water behaves like energy as it flows and isn’t recycled locally
Explain the nitrogen cycle
Nitrogen is important, but most is in atmosphere, and so plants can’t absorb atmospheric nitrogen
Thus, it is absorbed as ammonium or nitrate after fixation of nitrogen by symbioticn bacteria or in soil solution
denitrifying bacteria convert nitrate back to gaseous nitrogen
Explain the carbon cycle
It is a global cycle
Most C is locked up in Earth;s rocks as carbon and fossil fuels
Most active pool is CO2. CO2 is used in photosynthesis, and released during respiration
Large amounts of CO2 is dissolved in the ocean
Burning fossil fuels return CO2 to atmosphere faster than it can be cycled –> global warming
Explain the phosphorous cycle
Essential to all life - in ATP
Not common in Earth;s crusts or in atmosphere
Taken up by plants as phosphate from sparingly soluble soil storage pools
Aus flora well adapted to low P and efficient at recyling P
Symbiosis between plant roots and mycorrhizal fungi enhances P supply for plant, and fungi get sugars in return
Explain Aus conditions
2/3 of mainland Aus in desert –> low N, P, and rainfall is variable
Desert ecosystems productive in pulses when rain falls or from utilisation of reserves
Consumers must then adopt a pulse aanr reserve pattern, eat reserves of other organisms and adopt opportunistic feeding in habitats
What is a trophic cascade
When changes at one level of a food chain (usually at predation level) has a ripple effect on lower trophic levels –. impacts ecosystem structue and function
Trophic cascades occur when predators limit the density and/or behavior of their prey and thereby enhance survival of the next lower trophic level.
Double check this
Give an example of the impact of trophic cascades on the carbon cycle
Sea otters eat sea urchins which eat kelp –> increased sea otters –> more kelp –> more photosynthesis –> greater absorption of CO2
Sea otters thus drive a very significant CO2 storage, as seen in the kelp carbon pools
How do human activities affect ecology of natural systems
Being contributors to global warming, pollution , development of cities, oil spills etc which all disrupt the ecology of the natural systems
What is contamination
Presence of a substance where it shouldn’t be, or at concentrations above background
What is pollution
It is contamination that results in or can result in adverse biological effects to resident communities
What is the difference between contamination and pollution
Contamination is the presence of that potentially toxic substance, whereas pollution is the actual toxic substance causing harm
What did Rachel Carson do
Wrote silent spring which was written in a public science way to help public understand. It was warning of the synthetic chemicals accumulating in birds and mammals (especially seen in birds of prey)
What is bioaccumulation
WHen intake > secretion in terms of a pollutant
Occurs when organism absorbs a toxic substance at a rate greater than that at which the substance is lost
Bioaccumulation in all body tissues
Particularly seen in predators at top of food chain
What is biomagnification
Occurs when there is an increase in concentration of substance in tissues at higher trophic levels
What are the impacts of pollution on humans? Give a case study
Case study on Inuit of north canada, where PCBS were found in breast milk of inuit mothers as well (Indigenous), despite no direct exposure to it.
They actually had 5x the PCB levels, and 2/3 of children had unacceptably high levels of PCB, despite no manufacture of PCB in canada
Ultimately, it was due to women eating PCB contaminated fish, and giving birth. Children exposed to PCBs in uterus had lower childhood growth rates
How did PCBs get there?
Inuit ate almost every bit of the 100s of narwhal and beluga whales taken every year, with a preference for muktuk (surface fat, which has high conc of PCB_
utltimately it is due to ‘global distillation’ and ‘global fractionation’ - where volatile chemicals are transported long distances, and concentrated in certain regions of Earth such as polar areas
Heavy use of PCBs in tropics, where they evaporate from soils, carried on winds (fractionation) and then condense out into snow as toxic snow or rain (distillation)
Systematic transfer from warm to cold, a very slow breakdown in cold climates
What were solutions to PCBs
Global solutions; PCBs are now banned worldwide
Monitoring and regulation
What are the problems with lead
Hunting rabbits w/ lead shots in the 1900s –> condors ingest lead after feeding on carcasses of animals that humans have shot –> lead poisoning –> led to intensive captive breeding and medical intervention - requires perpetual support
Lead poisoning severely damges birds nervous systems and impairs liver and kidney function
22 condors in 1982. This should have led to extinction, however, in 2008, the califorina banned use of lead shots and birds were reintroduced (but feather and blood samples show no discernible difference in lead levels after and before this law)
What is habitat fragmentation
Process where a large continuous habitat is divided into smaller, isolated fragments due to human activities like roads
WHat is the major contributor to biodiversity loss
Habitat loss
What are edge effects and explain its significance with habitat fragmentation
The microbiome on the edges are different to the core habitats (centre of the microbiome). Some species like the edge whilst others dont
The centre of large habitats are called core habitats. Small fragments can’t support as much core habitat as large fragments, because small fragments are all ‘edges’ –> some species are unable to live in that enviro
Although some species benefit from edges, most sturuggle. Very fragmented ladnscapes = greater edge effect, and species reying on interior environment are especially vilnerable
What are the two effects of fragmentation
Biomass collapse
Ecological meltdown in predator-free fragments
Explain biomass collapse as a result of fragmentation
Experimentally fragmented landscape, where patches of 1,10 and 100 ha were isolated and fonnd that rate of biomass loss is greater near forest edges (ie. small patches)
Decline in above ground biomass after fragmentation –> higher the mortality, no recruitment of new trees
Thus, smaller patches –> increased rate of biomass loss
This is the case because microclimatic factors strongly affecte don edges (like wind, hydrology)
Explain ecological meltdown in predator free fragments as a result of fragmentation
Habitat fragmentation could lead to lokss of large animals. This has consequences on the lower trophic levels
This is seen in the construction of a dam in Venezuela, where a large lake was made with multple islands. Small and medium islands dont support > 75% of vertebrates from mainland –> most large animals and predators lost, and the remaining vertebrates are small,insect or seed predators or herbivores, which are hyper abundant
Predators of vetrtebrates were absent –> densities of rodents, howler monkeys, iguanas, leaf cutters were 10 to 100 times greater than on the mainland –> predators normally limit them
Densities of seedilings and saplings oof canopy trees are severely reduced on herbivore affected islands –> forests cant recover –> evidence of trophic cascade due to absence of top down regulation –> ecological meltdown
What are the ecological impacts of climate change on animals and plants
Range shifts (latitudinal or altitudinal)
Abundance changes
Change in growing season length
Earlier flowering, emergence of insects, migration and egg laying insects
Morphology shifts
What are the ecological impacts of climate change on hydrology and glaciers
Glacier shrinkage
Permafrost thawing
Water freeze and earlier break up of river and lake ice
Explain the extent of the extinction crisis
More than 45 300 species are threatened with extinction
There have been an increase in extinction rates due to human activity since the year 1500 –> rate of extinction is 10-100000 times higher than background rates (should only be 1 speciess extinct every few years)
Aus has lost ~34 species in the last 200 years (80 species of mammal extinct, 60 in the last 200 years)
What proportion of non flying critical weight range mammals are extinct or threatened
Critical weight range describes the weight range from 35g - 5.5kg
Overall, >30% of nations non-flying mammals are in the critical weight range
What were our faunal losses
41% marsupials, 65% rodents
In Western NSW, since colonisation, 27 have gone extinct
What are the aims of conservation biology
To describe problems and understand procceses
To predict impact of threats
To develop solutions; undo ‘human footprint’
Ultimately, stop more species/communities/ecological processes from going extinct
What is the evil quartet
Alien species, over-hunting, habitat loss, co-extinction
Explain the acronym HIPPO
Habitat Loss
Invasive species
Pollution
human over Population
Overhunting/overharvesting
Explain the problem of alien species
Alien species can ruin the ecosystem that has been working for a while. In this sense, it interrupts how well the ecosystem functions and affects the food chains negatively –> ultimately could lead to some extinctions (especially if these are predatory alien species)
Aus has 56 introduced species of vertebrates - some have significant impacts (~$1 billion towards managing vertebrate pests, ~$4 billion managing weeds)
New invaders bring new megafauna –> impacts through more grazing and hard hooves which further soil erosion
A lot of our farm animals are feral, with many being major pests
How did alien species get here
Deliberate introductions;
Acclimatisation sources (comfort/familiarity)
Ornaments
Agriculture
Domestics
Biological control (i.e. cane toads)
Human traffic;
Trade routes
Ease of global travel
Native Invaders
What is the tens rule
1/10 of plants and animal species brought into region will escape to wild
1/10 of those escaped species become naturalised (live in a region where it’s not naturally from)
1/10 of those will become invasive
Whaat are the common characteristics of invasive species
High reproduction rates
Great ecological dispersal
Great ecological flexibility
Traits of a pioneer species
Flexible diet
What are the impacts of invasive species (i.e. example w/ red fox)
(case study on red fox)
They ultimately compete w/ other marsupials, and preys on anything
This led to the 12 extinctions of mamals and caused threats to; 48 mammals, 14 birds, 12 reptiles and 2 amphibians
Fox distribution is limited by and facilitated by rabbit distribution, but suppressed by dingo
Explain overhunting as an issue
Humans normally over-exploit wildlife because of overhunting for food or resources –> likely to lead to the extinction of a species (or decreased species population at least)
Explain habitat loss as an issue
Habitat destruction is the major cause of species extinction
Ultimately, by destroying the habitats of animals, it reduces the animals’ ability to have successful interactions with the environment to facilitate their survival –> threat to species populations
What is island biogeographic theory
Suggests that reducing habitat area to 10% of its former extent will eventually cost about 50% of species dependent on the natural habitat to disappear
In other words, the fragment size and isolation of a fragment can impact the survivability of species there
What is extinction debt
Reflects future ecological cost of current habitat destruction
Extinctions occur generations after fragmentation
Extinction debt is the future extinction of species due to events in the past.
Moderate habitat destruction is predicted to cause time-delayed but inevitable, deterministic extinctions
WHat is coextinction
This is where critical ecosystem functions are lost when some species are lost (become extinct). Especially relevant as some species play critical roles in the ecosystem, and if they become extinct, the ecosystem might not be able to fully function properly
For example Haast’s eagle in Nz went extinct after its main prey; moa were hunted to extinction
Also occurs w/ parasites and hosts - passenger pigeons were once the most numerous bird on the planet ( >5 billion birds), but were hunted to extinction in USA –> led to the coextinction of 2 species of bird louse
Why are experiments important? Give an example
Key to identifying processes driving extinction and allowing management and future predictions to be made
I.e. predation experiments (removal/supplementation)
Meta-analyses; looks towards general pattern across studies
For example, the Operation Western Shield was an experiment where 1080 poison was used, which is a natural poison, so the native animals in that area were already adapted to the poison whilst the introduced species weren’t –> alien species died
Why is modelling important? Give an example
Important for being able to predict the impact of certain changes in the ecosystem (also allows for the identification of different management options)
I.e. the population viability analysis (PVA) is a mathematical model which predicts likelihood of a particular species to survive or go eextinct within a particular time frame, and also within hypothetical situations (i.e. natural disasters) (However, there is a very data hungry process)
Explain impact of wildlife sanctuaaries on conservatism
They have been effective in being able to act as safe havens for some wildlife
I.e. Scotia managed by Aus wildlife conservatory –> allowed for the reintroduction of a couple species. This was achieved through things like predator fencing, invasive animal and weed control as well
WHat is ecologoical restoration
Process of repairing damage caused by humans to diversity and dynamics of Indigenous ecosystems (restore ecological functions)
What are the goals of ecological restoration
Restore ecosystems to pre-impact or reference state (important for comparison)
Enhancing habitat qualities
Restoring ecosystem functions via reintroductions
Restoring degraded landscapes (i.e. Bauxite mining in Darling Range where clays are extracted –> restoration goals –> eight years after mining –> revegetation approaching pre-mining levels )
Does ecological restoration work? Include an example
Studied the existing remnants, pastures and restored areas in the focal area of Cumberland Plains (it is a crtically endangered ecological community under NSW legislation, with numeorus threats from clearing for Ag, urban dev, pollution etc)
The ecological work included increased pollination, seed dispersal, herbivores, reducing parasitism and predation by invasive species
Does revegetation foster recovery of landscape?
In the example above, it led to numerous beneficial effects:
1) Structural attributes returning w/ less floral diversity
2) Increased seed dispersal by ants –> function returned quickly, not limited to assemblage composition but identitity of key functional groups
3) Insect pollination –> replacement of native pollinators, similar services in a different way
4) Beetle assemblages –> “FIeld of dreams” hypothesis supported (restoration efforts that create suitable environment could lead to recovery of remaining aspects of ecosystems through natural processes)
