all Flashcards
define conservation biology
applied scientific discipline seeking to counter biodiversity loss
- response of biologists to anthropogenic impacts on natural world
what are the 3 components of conservation biology?
and what is it concerned with?
- quantify loss and impacts
- identify causal mechanisms
- devise strategies to reduce impacts
concerned with long term viability of entire systems
give 2 examples of how you may quantify loss and impacts
- avian bird monitoring : farm and woodland bird species declined with 50% drop in farmland birds
- study urban development as fastest growing land used quantify impact on species richness, pop densities, genetic diversity, predate/disease risk
give 2 examples of identifying causal mechanisms
- wood warbler: 1995-2008 60% pop decline, most specialised in African wintering habitat so change here likely causal factor
- plant pollinator interactions such as between oil collecting bee and oil secreting orchid, plant decline may be due to climate change or reduced pollination in urban area
explain protected area gap analysis and skylark plots as examples of devising strategies to reduce impacts
- protected area gap analysis: gap species are threatened by extinction but not in protected areas- identify where species live without protection., analyse where higher priority gaps in protected areas, designed in relation to patterns of species
- skylark plots: decline due to switch in farming type, can spray an area of field with herbicide so natural vegetation can grow benefiting birds but many are against it making their land look poor- fields with 2 plots per hectare have significant benefits and improve foraging and breeding success of the birds
what is the noble savage concept?
in ancestral times was believed there was harmony between humans and nature but incorrect
- lower pop density= fewer resources= resource overuse= damage to natural world
give 2 examples of the noble savage concept
- pacific islands- colonised <3000ya, over 2000 bird species extinct (10% all bird species) due to human colonisation and introduction of non native species
- easter island- off coat S.America, colonised 318AD, deforested 1400AD, forest used for fuel, timber for houses, boat making for fishing which also led to overfishing, all natural resources lost and society extinct
what 3 main conclusions can be made from the noble savage concept?
- human have always impacted natural world (concept is wrong)
- some species benefit
- are shifting baselines
- where is there higher deforestation rates?
- what % UK temperate forest
- why may rates have increased?
- tropics
- 12%
- increased pop size so more damage
why has the time taken to add 1 billion to a pop decreased and what is it thought the pop will stabilise at by the end of the century?
rapid pop growth
10 billion
- what % global available energy used by humans
- what % local energy do industrialised nations use
- what % globe bears footprint of our change
- what % fertile land is used by humans
- 20-30%
- 60-80%
- > 80%
- 98%
how does human pop growth and resource use lead to loss of biodiversity?
more industry, agriculture, fisheries, forestry leading to land use and cover change, altered bio geochemical cycles, natural compounds harvested, biological invasion
what is crisp discipline?
response to rapid biodiversity loss
what other disciplines may need to be applied when identifying causal mechanisms to reduce impacts and what needs to be taken into account?
economic and social science
need to take local peoples attitudes into account and their say over the situation
whats the relationship between rate of biodiversity loss and knowledge gain?
rate of biodiversity loss > rate of knowledge gain
give 3 points about biofuels
- generally considered carbon neutral
- can’t be grown on agricultural soil
- oil palm often used but has led to mass forest destruction and extinction of orang-utans may follow
what is the kakapo example?
- nocturnal parrot in New Zealand
- used to be common but declined when settler introduced domestic animals that predated them
- moved to predator free offshore island, supplements given to increase breeding to every year rather than 3-4 years
- biased sex ratio with mainly male chicks
- new resources added and sex ratio restored
what was the romantic transcendental ethic in 1850s and who were the leaders?
leaders: John muir, Henry throeu, Ralph Emerson
- semi religious idea
- believed in preservation and leaving the world untouched
- not economically value focused
- led to Sierra club,, preservationist movement, Yosemite, national park
what is the resource conservation ethic in 1900s and who were the leaders?
leaders: John mill, gifford Pinchot, teddy roosevelt
- practical approach
- aligned with ecosystem service approach
- aim to protect nature due to economic reasons
- led to multiple use concept
what is the evolutionary ecological land ethic?
- 1950s Aldo Leopold merged resource conservation ethic and romantic transcendental ethic, avoiding muirs semi religious aspect and mills strict utilitarian approach
- view that ecosystems are integrated systems based on interdependent processes and that components can’t be tinkered with without risking collapse
- foundation of modern conservation
when was the first modern conservation biology textbook published and by who?
1980- Soule and Wilcox
what 2 reasons are there for why we select conservation units?
- essential for effective and efficient planning given limited space
- aim to protect biodiversity
how much money is actually spent on global conservation and what is the required spend fo James et al and McCarthy et al?
James: $27.5 billion required $6 billion actual (20%)
McCarthy: $78 billion required actual 10% of this
define biodiversity
the variability among living organisms within species, between species and of ecosystems
what’s the difference between the units of the taxonomic and ecosystem approach as conservation units?
taxonomic: genetic diversity, populations, sub species, species
ecosystems: habitats and ecosystem services
give 6 factors about the genetic diversity unit
- diversity important for increasing pop resistance
- more diverse a pop the greater the capacity to cope with changing environments
- preserving ancestral plant species can help better breed plants and may improve yields in closely related crop species
- varies spatially
- just because is diverse doesn’t mean it contains unique species
- without knowing extent of diversity this conservation unit may not be practical
define population
a group of the same species whose members can interbreed
what 3 things does having multiple populations increase the probability of and mean that you would use it as a unit?
- maximising genetic diversity
- protecting local adaptations
- insurance against local disasters
where may genetic data be lacking to determine if separate populations?
in the black pine in Europe as some species distributions are distinct but others not so obvious and can occupy many areas
what issue may focusing on populations as a unit lead to?
parochial (local not global interests) and inefficient conservation
describe the great crane project as a local rather than global success
1600: cranes extinct in UK
1980s: recolonised but only about 10 pairs
2009: reintroduction programme £400,000 per year to increase UK numbers
2015: first breeding of reintroduced birds
- the European pop has had a large increase since 1990s and are IUCN least concern
- 11 other crane species are threatened with global extinction
- UK species not at global risk so only locally successful and money better spent on globally endangered
give 6 disadvantages of population as a unit
- pop are difficult to define
- based on assumptions of genetic divergence between pop which is rarely tested
- often multiple pop
- more focus on local concerns rather than global
- some distributions unclear
- can lead to a narrow outlook and inefficient conservation
what is more likely conserved if a sub species is conserved and used as a unit?
species genetic diversity and more unique adaptations
explain an example where investment in subspecies conservation failed
dusky seaside sparrow
- subspecies restricted to Florida
- $2.5 million investment
- extinct in 1990
- no genetic differences in subspecies, are genetically identical to non threatened sub species
what % of continentally distributed again subspecies lack genetic distinctiveness?
and why may this make sub species based conservation problematic?
98%
assumes sub species represent genetic variation
promotes parochial conservation
give 4 advantages of species as the traditional conservation unit
- species irreplaceable
- public understanding
- data most frequently collected at this unit
- easy to recognise and define
give 3 disadvantages of species as a unit and examples for 2 of them
- unsuitable taxonomy (Manx shearwater of least concern and balearic shearwater that’s critically endangered with 7.4% decline each year split in early 1990s)
- taxonomic inflation (in Philippines may be >100 extra avian endemics, used to be 13 albatross species now 21, 33 lemur species in 1994 now about 100)
- most species undescribed
what % of these terrestrial species are described?
- fungi
- animals
- protozoa
- algae
- plants
- 7%
- 12%
- 22%
- 47%
- 72%
why were habitats developed as a conservation unit and what are 4 advantage ?
in response to accusations that species focused conservation ignores many species
+ will likely protect a great deal of species
+ habitat loss major driver of extinction risk (80% endangered terrestrial vertebrates threatened with habitat loss)
+ reasonably good data on habitat loss
+ protect ecosystem services
give 2 disadvantages of habitats as a unit and and example of why for each
- at a finer scale habitats difficult to define (oak woodland may contain other trees so can’t generalise it as oak)
- easy to miss parts of habitats with the most species if species have a small range (frogs have around 1,000 species in 100km cell)
when did millennium ecosystem assessment start and what does it assess?
2001- assessing impacts of environmental change on human wellbeing
what are the 4 ecosystem service types in detail?
- supporting services (for production of other ecosystems services such as primary production, nutrient cycling)
- provisioning services (products obtained from ecosystems- food, freshwater, wood)
- regulating services (benefits obtained from regulation of ecosystem processes including climate, disease, floods, water purification)
- cultural services (non material benefits such as aesthetic, mental wellbeing)
explain the pollination and productivity examples for provisioning services
- pollination- key for food crops and fruit and seed production with a global value of $27 billion per year
- productivity- primary productivity increase with plant species richness (more grass=more cow milk)
explain the sea defence example for ecosystem regulatory services
- super cyclone orissa in India 1999
- flooding and tidal surge
- mangroves buffered villages slowing down the surge and reducing deaths by 69% in villages <10km from the coast
explain the wellbeing example for cultural services
- children in high rise flats have higher concentration levels when views of green space
- people in parks with more plants have greater mental well being
what increases when ecosystems are sustainably managed?
net economic value
give 7 disadvantages of ecosystem services as unit of conservation and example
- ecosystem diservices (malaria costs Africa $12 billion per year due to healthcare, lost work days, tourism loss)
- lack of data (only 4 services mapped : c storage, c sequestration, grassland production, water provision)
- limited info on relationship between biodiversity and ecosystem service provision
- biomass may be more important than species number
- cultural services depend more on perceived to actual biodiversity
- service provision may be dependent on large numbers of people
- lack of spatial harmony between ecosystem services and biodiversity
roughly how many species of these?
- amphibians
- fish
- mammals
- flowers
- 6,500
- 31,500
- 5,500
- 215,000
are humans evenly distributed?
no- some occupy areas of higher human pop density so experience more threats
what are the 4 main methods of priority setting?
- taxonomically unique species
- keystone species
- umbrella/flagship/indicato species
- rare/threatened species
in terms of taxonomic distinctiveness what is the New Caledonia birds example?
Kagu and green backed white eye
the white eye is the sole family representative with greater conservation importance, representing more genetic and functional diversity
who formalised the distinctiveness equation and when and what is it?
vane wright 1991
distinctiveness= max branches from root/ branches from root for that species
what are 4 modifications for the distinctiveness equation?
- counting shared nodes not branches
- taking branch length into account
- future distinctiveness
- combine with other metrics but only works for some groups
what is mays equation for distinctiveness?
= max no. of descendents on path from root/ no. of descendents on path from root
define keystone species and what role do they play in an ecosystem?
’ a species whose impact on its community is large and disproportionally larger relative to its biomass’
keeps ecosystem intact and maintains species richness
describe the starfish in N America as a keystone species (Paine 1966)
in rock pools- when removed system collapsed from 15 to 8 species
starfish are predators preventing other species from dominating as if this happens other species will be excluded by competitive exclusion
what is the community importance index and what does it mean if it is over 1?
change in community trait/ change in focal species biomass
if >1 keystone species
in what 3 ways is keystone species a limited approach for assigning priorities?
- many keystone species are only identified from anecdotal evidence
- robust identification of species difficult and often needs removal experiments
- a few non keystone species can have equivalent effects
briefly describe the umbrella/flagship/indicator species priority setting approach
shares concept that protecting single species can protect many
differ in characteristics from focal species
can aid conservation but if used in isolation won’t generate enough protection
what is an umbrella species?
species that require a large area for conservation
- protect other species with similar habitat requirements
- usually large vertebrates with large home ranges
give an example of an umbrella species
saiga antelope
1950- 2 million
2010- 95% decline now critically endangered
- many areas of former range extinct due to change from natural habitat to agricultural land and hunting pressures
what is a flagship species?
characteristic species that promotes conservation of region/habitat
explain the seahorse and Chinese panda example for flagship species
seahorse
- se grass beds provide habitat and nursery area for fish and are important in C cycle
panda
- aim to protect their bamboo areas
- but is a lot of bamboo in areas where pandas extinct
- is less of a need to protect bamboo areas if panda extinct but this ignores other important species living there
what is an indicator species?
species with narrow ecological tolerance and so are found under specific sets of conditions
- help to protect indicated habitat
- if indicator species disappears incentive to protect habitat may decline
give 3 features of rare species
- small geographic range size
- small pop size
- habitat specialist
who proposed the 7 kinds of rarity chart?
Rabinowitz 1981
the great white shark and devils hole pupfish are both rare but whats the difference?
shark lives in many oceans of different sea types but the pupfish Is isolated
not all rare species are threatened - give an example
seychelles small day gecko
- endemic with small geographic range
- high density and pop size
- broad specificity
- naturally occur in forests but can survive in agricultural and urban areas so unlikely to go extinct
common species can become rapidly extinct explain the extinction of Rocky Mountain grasshopper
very common in US around 1880 but 30 years later in 1902 they became extinct - perhaps loss of breeding habitat as grassland became agricultural
explain the extinction of the passenger pigeon
25-40% N.American birds passenger pigeons
3-5 billion when europeans discovered America
extinct 1914
explain the extinction the American chestnut tree
abundant on eastern seaboard
pops destroyed by fungal pathogen (95% decline)
leaves nutrient rich and decay rapidly which led to alterations in nutrient cycling and decrease in freshwater stream invertebrates
what are common species important for??
functionally important for ecosystems
what is population viability analysis for prioritising species by extinction risk?
- based on detailed demographic data on current pop size, birth and death rates and how vary with environment
- but impractical for most species as insufficient data
give 7 features of the IUCN red list
- started 1960s
- 65,00 species assessed
- all birds, mammals, amphibians, corals
- global assessments for fish and plants underway
- rate of assessment increasing
- identifies species at risk of global extinction and drives conservation for those species
- could be considered subjective categories
what are the 5 aims of IUCN red list ?
- classify threat to assign priorities and measure conservation progress
- consistent when used by different people
- improve objectivity through clear guidance
- facilitate comparisons across taxa
- give people using lists better understanding of classification process
what % pop size reduced and how much area of occupancy for each:
- critically endangered
- endangered
- vulnerable
- > 90%, <10km2
- > 70%, <500km2
- > 50%, <2000km2
what are near threatened species?
likely to qualify for threatened category in the near future
what 6 things are the IUCN evaluations based on?
- range size
- pop size
- no. of pops
- severely fragmented pops
- pop trend
- extreme pop fluctuations
what are the 2 types of range size?
- extent of occurrence (area within range boundary)
- area of occupancy (occupied grid cells)
what is pop size?
when looking at pop size what must reintroduced individuals have done before being counted?
number of sexually mature individuals capable of reproduction
reintroduced must have bred successfully as usually struggle to behave normally and usually have lower reproductive success
what is the number of populations (IUCN)?
number of distinct groups with little demographic or genetic exchange
when looking at severely fragmented pops where are most individuals found?
what data is usually used?
in small, isolated subpopulations
data on distribution of habitat usually used as little info on links between populations
how is population trend considered for IUCN?
when is a species considered endangered?
- over 10 years or 3 generations
- important for long lived animals such s elephants
- observed, inferred or suspected in past or predicted in future
- endangered if decline >50% with unknown, continuing or irreversible causes
what are edge species?
evolutionary distinct and globally endangered
- nearing extinction
- giant salamander, purple frog, social lapwing
(but just because extinct doesn’t mean functionally important in ecosystem)
what 3 types of sites does conservation usually target?
protected areas, wider landscape conservation, specific management
for protected areas what are the arch targets for 2020? and what is the half-earth goal?
17% land/freshwater is protected areas
10% marine protected areas
half earth goal= 50% terrestrial land under protection
what is an example of wider landscape conservation?
restoration and agri-environment schemes which pay farmers to look after environment
what are specific management sites?
sites selected to maximise effectiveness, such as invasive species control as can lead to extinction of other species
what are the 2 scales of prioritisation?
global- selection of large regions of conservation value , important for biodiversity, well defined prioritisation schemes, not very robust
local- specific localities within hotspots, more limited standardisation for choosing areas
what are the 9 prioritisation strategies for global scale?
CE: crisis ecoregions BH: biodiversity hotspots EBA: endemic bird areas CPD: centres plant endemism MC: megadiverse countries G200: global 200 ecoregion HBWA: high biodiversity wilderness areas FF: frontier forests LW: last of wild
who proposed the biodiversity hotspot concept, when, what was the criteria and what was discovered?
Norman Myers 1988
- at least 1500 endemic vascular plants
- <30% area retains original natural vegetation
- found 35 hotspots covering 2.3% land with 50% worlds plants, 43% birds, mammals, reptiles, amphibians
what 2 things are global strategies based on?
vulnerability and irreplaceability
what is vulnerability? what 4 things is it measured as? what are 3 good indicators of vulnerability? and what is one downfall?
likelihood biodiversity values are lost in a site
- % habitat loss
- human pop density
- protected area coverage
- total forest cover
indicators:
- total forest cover poor indicator
- habitat loss assumes current loss predicts future loss
- human pop density and protected are coverage only ok
BUT: no schemes use number of threatened species, some prioritise high vulnerability others low
what are irreplaceability indicators?
the extent spatial options for conservation targets are reduced when a site is lost- depends on pop size, dynamics, distribution
what is the most common irreplaceability indicator and what is there a strong relationship between?
endemism
strong positive relationship between plants and endemism in different groups
at the local scale of prioritisation who and when was the nature conservation review and what is it?
1977 Derek ratcliffe
aimed to find a way to select the best wildlife sites in UK- is the min set of locations to protect biodiversity
what 10 criterion needs to be critically assessed at the local scale of prioritisation to provide a good understanding of key issues?
- size
- diversity
- rarity
- naturalness
- fragility
- typicalness
- recorded history
- position in ecological/geographical uni
- potential value
- intrinsic appeal
what do larger sites contain?
more species, larger population, fewer edge effects
what does having less of an edge effect mean?
less external activity pressure from human intrusion into reserve which would degrade quality
why is high habitat diversity good and what are downsides of it?
+ promotes high species richness
+ multiple habitat sites for species at different stages of the life cycle
- only valuable if all habitats of high quality
- can reduce species richness as habitat specialists or generalist species can’t maintain viable population
why may it be naive to prioritise sites with high species richness ?
not all species are equal
which is threatened and which is irreplaceable?
a) less species, more endemic, less threatened species
b) more species, less endemic, more threatened species
a) irreplaceable
b) threatened
what may a site containing very generalist species be an indicator of?
degraded habitat
does it make more sense to study specialist species or total species richness?
specialist- changes which site is the optimal choice, more accurate
when looking at rarity what needs to be considered?
long term viability
what are the SSSI guidelines for the Natterjack toad?
includes established and important sites
established: those occupied for over 5 years
important: those with populations larger than the average
areas least modified by humans should be prioritised as are the most natural but what are 3 issues with this?
- difficult to quantify
- most areas highly modified
- human modified areas more valuable
in terms of fragility and threat which sites are most worthy of protection and when does it apply?
sites with more threatened species/habitats
- only if threatened countered by site based protection but often this not the case such as for N deposition or said rain
in terms of typicalness which sites are considered better to protect?
what is an issue with these kinds of sites?
sites most characteristic of focal habitat
- a set of species representative of each habitat to which an ideal set is compared at each site
BUT: causes selection of similar sites so little variety
in terms of recorded history what sites need protection and why?
sites with long history of ecological research- helps us understand the natural world as are indicators of environmental change due to humans and climate change
why may sites at the edge of distributions be more variable?
- data on limiting conditions can inform management
- unique local adaptations
- facilitate range shifts in response to climate change
what needs to be considered about a sites value?
if it will increase in the future and if there’s potential to contribute to habitat restoration, also educational value needs to be considered
in what 3 ways can climate change increase or decrease sites value in the future?
- changing habitat type
- focal species moving away from reserve
- new species may colonise
in terms of intrinsic appeal what sites are more important?
sites with charismatic taxa
- can be right approach if want to conserve recreational ecosystem services
beyond ratcliffe’s criteria what is the representation idea?
each species must be represented by at least one viable population In protected site
why may Ratcliffe’s criteria not be relied upon for representation?
globally 300 critically endangered vertebrates aren’t in protected areas
in terms of cost effectiveness explain the Australian nature reserves example
- the target is 15% of each of 58 major habitats are in protected areas
- the conservation benefit increases with cost of purchase of land and management but is massive variation
- replacing the least effective 1% keeps costs the same but increases no. of habitats, meeting the target from 18 to 54
give an example of a species with a small geographic distribution and population size
snow bunting bird in Scottish highlands
what increases the risk of extinction and give an example of a species with a population like this
small populations
e.g. big horn sheep in North America- if less than 15 individuals the species becomes extinct
what is the relationship between pop size and extinction risk in birds of Californian Channel Islands? and below what pop size is extinction rate accelerated?
strong non-linear relationship
below 100 extinction accelerated
what are the 4 reasons small populations are vulnerable?
- environmental stochasticity
- demographic stochasticity
- behavioural factors (Allee effects)
- genetic factors
what is environmental stochasticity?
chance events that disrupt populations/extrinsic
- often synchronised over large areas, especially climatic events
- deterioration in environmental conditions has big impact on populations
- even species with large ranges adversely affected
why are plants often more resistant than vertebrates?
seeds and tubers can buffer pop from environmental change due to dormant and stress tolerant life forms
in terms of environmental stochasticity what is the Montserrat oriole example?
- 4 major volcanic eruptions (1995, 2001, 2003, 2006)
- many died quickly
- direct impacts: volcanic dust and 75% habitat loss (density independent)
- indirect impacts: lower food abundance due to acid rain caused by volcanic dust interacting with rainfall which impacts food chains (density dependent )
in terms of environmental stochasticity describe the Coachella valley fringe toed lizard example
drought induced pop fluctuations with pop size decreasing with a decrease in rainfall
what is demographic stochasticity?
chance events that disrupt pop growth/intrinsic
what usually is there between pop size and demographic success and due to what?
negative density dependence due to intra-specific competition BUT: can be positive density dependence and Allee effect where population growth rate is reduced by under crowding
the Allee effect is often found in flowers pollinated by animals- explain the C.concinna plant example
- breeding success depends on external pollinators
- certain density needed for efficient pollen transfer
- probability of pollen transfer reduced the further apart plants are
- impacts breeding success of rainforest trees
- pollinators more likely to go to larger flower clumps
Allee effects can occur in social animals- give an example for each:
- predation
- foraging effectiveness
- willingness to mate
- colonial birds group for defence
- pack hunters such as wolves hunt better in larger groups
- flamingos more likely to mate in larger groups
give an example of a bird that the Allee effect applies to
lesser kestrel who has higher reproductive success and adult survival in large colonies
it can be hard to find mates if a population density is low- why?
- large home ranges
- competition for mates from other individuals
if population growth rate is below 1 what can occur?
Allee effects can drive species to extinction
what is allelic richness?
no. of alleles per locus
what does having a small population reduce?
genetic diversity
what is population size?
- no. of individuals vs no. breeding individuals
- proportional contribution to gene pool that counts
- where individuals have an equal contribution to the next generation and no selection is occurring
what did wright discover in 1931?
the more individuals the lower the change in heterozygosity when studying a closed population without mutation for heterozygosity
what is the effective and census pop size and which is often lower?
effective pop size often lower
effective= prop. of contribution to gene pool
census= no. of individuals in pop
why is the H.amarus fish vulnerable to inbreeding?
lots of individuals but little contribution to gene pool
in detail in what 3 ways is the effective population size reduced?
- not all individuals mate or some contribute more offspring than others
(uneven sex ratio- lek forming species may have a single male contributing more to next gen or non monogamous systems- females gain extra male pairs) - pop size fluctuates (years of low pop size means lots of genetic bottleneck)
- generations overlap (small mammals)
what does genetic drift include?
stochastic events that determine which alleles are passed on to next generation
alleles can be lost through generations but what can drift be reduced by?
mutation and migration
in what 2 ways is a loss of genetic diversity bad?
- deleterious recessive alleles more likely to occur in combination leading to inbreeding depression
- natural selection acts on genetic diversity and reduced diversity can lead to reduced evolutionary potential
why may heritability remain high in a small pop?
alleles with high fitness usually dominate
what may a small pop with limited genetic diversity have and so what evidence is needed?
high fitness
need evidence for impacts of low genetic diversity
what is the impact of genetic drift on new Zealand birds ?
pop size decreases, % hatching failure increases- impacts inbreeding depression
whats the impact of genetic drift on Atlantic salmon?
negative relationship between reproductive success and inbreeding depression
lower genetic diversity= lower reproductive success and more inbreeding
in a study on animals what % showed +ve correlation between fitness and genetic diversity
82%
whats reduced for populations with limited genetic diversity?
reduced evolutionary potential
describe the example for reduced evolutionary potential for the panel 2008 study
M.annua plant
- artificially selected for high and low pollen production levels
- lower genetic diversity the lower the trait divergence
- higher genetic diversity means can cope with more environmental conditions
- looked at closely related threatened species and unthreatened
- animals: 78% threatened had low genetic diversity
- plants: 75% threatened had low genetic diversity
what can genetic variation determine and example?
determine ecological processes and services
- primary production and energy flux for nutrient release and decomposition in aspen forests is higher when more genetic diversity
what 4 factors contribute to low effective population size which then leads to extinction?
- environmental variation
- more allee effects
- more genetic problems
- more demographic variation
explain in detial, with dates, the heath hen case study for an extinction vortex example and 4 potential reasons for its eventual extinction
abundant but confined to single small island
1870: 300 individuals
1890: 120-200
1900: 70 (conservation and management began- reserves and hunting ban)
1910: 2000 individuals
1932:extinct
could be due to…
- environmental stochasticity: dry summers so fires and cold winters
- demographic stochasticity: sex ratio bias and severe fluctuations
- genetic effects: inbreeding occurred so low heterozygosity and genetic variation
- disease outbreaks
give an example of a bird with a small pop that doesn’t have an increased risk of extinction
Socorro island hawk
- stable pop of 15- 20 pairs for several thousand years
- rare due to small pop, small range, habitat specialist
- can deal well with small pop size
whats the difference between small pop paradigm and declining pop paradigm?
pop decline is a continuum
declining- identifies and manages processes causing decline- often environmental degradation
give 2 points about the small pop paradigm
- rich in theory
- promotes local intensive management
explain the vaquita porpoise example as a firefighting approach
less than 30 individuals so likely extinct in next 20 years so action directed towards their conservation very last minute and desperate
give 4 points about the declining population paradigm
- less rich in theory
- aim to prevent a pop reaching a point where small population paradigm kicks in
- less intensive management over a larger area
- more proactive
declining population paradigm can apply to small populations - explain the spoon billed sandpiper example of this
- naturally rare species
- previously 3000 pairs, now <200
decline due to… - low breeding success from disturbance and predation
- large scale winter habitat loss (east china sea where they travel has become more urbanised)
- low recruitment and hunting (often are caught when hunting for fish)
BUT: nit yet impacted by stochasticity, inbreeding, Allee effects
both small pop paradigm and declining can act together- describe the atitlan grebe example
initially DP then SP
lake Guatemala
- small pop experiencing decline in 1958 (DP)
- exotic fish introduced which were competitors for invertebrates
- human pop expansion led to reed cutting and loss of habitat
- conservation in 1960s where reed cutting banned in nature reserves and a net kept exotic fish out
- pied billed grebe arrives 1970s (SP) and hybridisation leading to pop decline
- 1970s earthquake (SP) which cracks lake basin, decreasing Leake size (environmental stochasticity)
- species driven to extinction
- multiple factors interacting so hard to diagnose the cause
why is it difficult to discover declining populations?
- geographic and taxonomic biases in monitoring
- many data deficient species so formal IUCN assessment can’t be carried out
what 4 methods need to be exploited in order to discover declining populations?
- take advantage of hap hazarding recording by naturalists
- interview local people
- spatial variation in factors driving decline
- biological correlates of vulnerability
marine life is hard to monitor so what can help and where has a major population crash been revealed?
keep track of no. of sightings that occur in an hour
anecdotal data on sightings and captures reveal the pop crash in Adriatic and Canadas east coast shark populations
in Yangtze what does interviews with local fishers reveal?
accurate estimates for pop decline in dolphin and puffer fish
- but need to take into account shifting baselines
- if most of the decline occurred before younger generations born their report won’t be accurate and the older generations may be
factors aren’t evenly distributed across the globe so what can we use to highlight where decline most likely?
maps
not all species decline- what is the theory behind this?
ecological and life history traits make population decline more likely for species in response to human activities
in terms of biological correlates of vulnerability
a) what does an increased body size mean for pop decline + 4 reasons
b) what does increased brain size mean for pop trend + 3 reasons
a) more -ve pop decline
- hunting pressure (Larger animals better food source and better indicator of hunting skill)
- larger animals have slower intrinsic rate of pop growth
- larger = longer lived
- raise fewer offspring
b) less rapid pop decline
- more behaviourally flexible
- can buffer more easily
- find food more easily
why are biological correlates of vulnerability limited?
geographic transferability limited (body size may be a better predictor in the tropics as more hunting there so the larger animals more vulnerable)
are species traits or environmental factors a less powerful predictor?
species traits
what 2 causes can lead to decline?
- demographic (reduced survival, breeding success)
- environmental
what does a complete simulation model such as population viability analysis require knowledge of and what may be an issue of this?
- needs knowledge of relationship between demographic traits and external factors
- for nearly all species the knowledge barrier too great to implement solution with sufficient speed
what is the comparative approach and what are the 2 main ways it is carried out?
- list plausible candidate factors for decline
- identify populations that differ in exposure to environmental conditions
- environments associated with changes in pop status can be identified
a) compare timing of decline and environmental change
b) compare populations in areas with different environments
environmental change may be causing the decline such as the corncrake bird- explain
- now confined to a few small Scottish islands
- decline correlated with grassland management switching to machine cutting
- led to rapid decline
give 5 issues with comparing timing of decline and environmental change
- often several environmental factors change simultaneously
- more machinery, chemicals, hedge removal, higher stock densities
- monitoring too infrequent to identify precise timing of environmental change to a pop decline
- spatial scale of pop and environmental monitoring differ
- time lags can distort relationships
give an example of where spatial scale of pop and environmental monitoring differ
fish stocks and marine life
- sea bird colonies monitored on land but may be responding to changing fish stocks away from colony
- often to enough data on where birds foraging to know which fish stock data to analyse
when would you compare populations in areas with different environments as the comparative approach?
when not possible to compare pre and post decline situations
explain the Madagascan endemic of the radiated tortoise as an example of the comparative approach where populations in areas of different environments are compared
- harvest for food and pet trade
- pop decline
- trade bans put in place bu not evidence trade was causing decline
- compared densities in a real with commercial trade and remotes sites
- found densities increase with distance from urban areas
- commercial hunters travel increasing distances
does correlation prove causation?
no
what are the 4 methods available to prevent diagnosis errors?
- check for individual movements
- test for all possible causes of decline
- check that the proposed cause alters demography
- check using manipulative experiments
what is the buffer effect?
if habitat quality varies then the highest quality sites will be occupied first and abandoned last
describe the common great tit example for checking individual movements to prevent diagnosis errors
- decline in pop in hedgerows
- incorrect that hedgerow quality declined
- move to woodland areas that have become vacant due to cold winters
- if prefer wood and can move between woods and hedges then any factor driving pop decline will lead to greater decline in hedges
give 4 points about testing for all possible causes of decline
- often impossible due to lack of data
- often lack of information from non breeding grounds of migrants
- need to acknowledge bias
- many studies only test the favoured hypothesis which can lead to incorrect diagnosis
explain the 2 examples for why it is important to test all possible causes of decline
a) yellow nosed albatross
b) NZ native birds
a) thought threatened by long line fishing but more likely due to avian cholera
b) major declines due to introduced predators but disease ignored and avian malaria likely to be the causal agent
give an example of why when trying to prevent diagnosis errors you must check the proposed cause alters demography
marbled mullet
- increase in number of breeders and fecundity
- 2000: insufficient food, more foraging
- 2001: less breeding success due to predation
explain the mangrove finch example for checking using manipulative experiments
- rat control decreased predation and increased fledging success
- but more eggs killed by parasites
- controlling flies as well as rat pop slightly increased persistence but not as much as the difference from increasing rate control
explain the recovery case study of line cratericola
- critically endangered plant
- 1966 discovered at 2 sites
- went extinct at 1 site when invaded by lantana camara, an exotic shrub
- large numbers of feral goats
- the hypothesis is that grazing and invasion causes the decline
- tested this in 1977
- put 2 groups of plants enclosed in goat proof fence and invasive shrubs cleared
- intensive goat control put in place
explain the skylark recovery case
1970-2008 was a 53% decline
- almost all decline farmland rather than moorland
- higher productivity on spring sown cereals than winter cereals due to reduced food availability in winter cereals
- recovery plots put in place
- increase breeding success by 50%
- decline reversed if 20% winter cereals had 2 plots per hectare
- economically profitable to farmer as is paid £500 to implement the plot
- but thought it can make their field look messy and indicate they are a poor farmer
when surveying you can conduct on a single site or compare multiple sites- describe each
single site: single point in time to discover, putting in place management plans and impacting assessments
multiple sites: survey biodiversity, habitat type/condition, status of key species to see if effective
what is surveying essential for and a benefit?
conservation planning- need fine scale distribution data
- cost effective
what is a downside to surveys and an example?
expensive
Ugandan forest is 15,000km2 and would take 100 years if 1 person surveyed it, costing $1 million
compare the complementarity survey approach with random site selection
complementarity selection more effective and rapid in reaching target number of species in network area
when can a survey be considered cost effective
if the cost of purchasing and managing extra land is more expensive than surveying
what is the Romeo error?
the rediscovering of new species
give an example of where the Romeo error has occurred?
Cebu flower pecker bird 1906: last seen 1959: declared extinct 1992: rediscovered surveyed the island after images from a plane crash showed forest still present so surveyed the island
