Flashcards in what to prioritise? species level (lecture 3) Deck (29)
Why prioritise conservation efforts?
- ideally would protect everything but non pragmatic to divide attention equally between all species
- humans are unevenly distributed, species near dense human populations experience more threats
- some species are more sensitive
What are the four main ways of setting conservation priorities?
- taxonomically unique species
- keystone species
- umbrella/flagship/indicator species
- rare/threatened species
What is taxonomic distinctiveness?
- formalised by Vane-Wright (1991)
- Distinctiveness (D) = max branches from the root / the number of branches from root for species
- modifications added
- May's distinctiveness: max number of descendants on the path from the root / number of descendants on the path from the root for the species
- terminal branch length
- future distinctiveness
- combine w other metrics like abundance
Why use to taxonomic distinctiveness to set priorities? Difficulties?
- sound and intuitive principle
- sole family representatives have greater conservation importance as represent more genetic (and often functional) diversity
- requires detailed taxonomic knowledge
- only works for some groups
Taxonomic distinctiveness example:
- kagu vs green-backed white-eye
- both kagu and green-backed white-eye endemic to new caledonia
- kagu only member of Rhynochetidae genus
- green-backed white-eye from genus with 75 species (Zosterops)
What is a keystone species?
- species whose impact on the community is large and large relative to their biomass i.e not just dominant species
- Community important index (CI): change in community trait/change in focal species biomass
- CI > 1 = keystone species
What is an example of a keystone species?
- upon removal of starfish system collapsed from 15 - 8 species
- starfish are predators that prevent competitive dominance & exclusion at lower trophic levels
What are the problems with using keystone species to set priorities?
- limited in use assigning priorities
- many keystone species only identified anecdotally
- robust identification difficult, often requires removal experiments
- a few non-keystone species can have same significance as one keystone species
What are umbrella/flagship/indicator species?
- all share basic concept that protecting a single species will help protect others
- characteristics of focal species differ
What is an umbrella species? Example?
- species that require large area for conservation
- protect other species with similar habitat requirements
- tend to be large vertebrates
e.g. endangered Saiga antelope
- declined 95% between 1950 and 2010
- critically endangered
- shared threat with other species: habitat destruction
What is a flagship species? Example?
- charismatic species used to promote conservation of a region/habitat
- can require small or large areas
- e.g. seahorse home range of 10m2
What are problems with flagship species driven priorities?
- useful concept
- can divert resources away from more effective conservation species for focal habitat
- implies focal habitat is worth less without focal species
What is an indicator species?
- species with narrow ecological tolerance
- therefore found only under certain set of conditions
- help to protect indicated habitat
- no specific area requirement
How useful is setting priorities by umbrella/flagship/indicator species?
- important concepts
- facilitate conservation but not problem free
- used in isolation will not generate adequate protection of other species
What is a rare species?
- Rabinowitz 1981: there are 7 different kind of rarity
- relate to intersections between geographic range size, habitat specificity and population sizes
- some species are naturally rare
- different types of rarity requires different conservation action
- rare species aren't always threatened
What is an example of a non-threatened rare species?
- Seychelles small day gecko
- endemic and v small geographic range
- 50,000 individuals, v high density
- can survive in agricultural and urban areas as well as natural rainforest habitat
What are examples of a common species becoming extinct?
- rocky mountain grasshopper
- went from abundant to extinct within 30 years, probably due to loss of breeding habitat
- passenger pigeon
- 3-5B individuals when europeans discovered america circa 1500
- 25-40% north american birds
- extinct in 1914
Why protect common species?
- american chestnut
- functionally important
- not exempt from extinction
- american chestnut
- nutrient rich leaves decay rapidly
- was abundant on eastern seaboard
- fungal disease decimated population by 95%
- majorly altered nutrient cycling and freshwater invertebrate assemblages
How are species prioritised by extinction threat?
- population viability analysis
Ideal: Population Viability Analysis (PVA)
- based on detailed up to date demographic data: population size, birth rate, death rate, how these vary with environment
- impractical for most species
How are species prioritised by extinction threat?
- IUCN red list
- International Union for the Conservation of Nature
- started in 1960
- 40,000 species now assessed
- all birds, mammals & amphibians & partial assessments for other taxa
- global assessments underway for fish, corals, and plants
What are the aims of the IUCN red list?
- classify threats to assign priorities & measure conservation progress
- consistent when used by different people
- improve objectivity through clear guidance
- facilitate cross-taxa comparisons
- transparency: give people using the lists a better understanding of the classification process
What are the IUCN red list categories?
- evaluated or non evaluated
- adequate data vs data deficient
if adequate data
- extinct, extinct in the wild, threatened, near threatened, least concern
- critically endangered, endangered, vulnerable
What do the IUCN threat categories mean?
- extremely high risk of becoming extinct in the wild
- very high risk of becoming extinct in the wild
- high risk of becoming extinct in the wild
- close to qualifying for above, or likely to qualify for above in near future
What are IUCN evaluations based on?
- range sizes
- population sizes
- number of populations: number of distinct
groups with little demographic or genetic exchange
(less than one individual/gamete per generation)
- whether populations are severely fragmented: severely fragmented populations - most
individuals found in small and relatively isolated
- trends in the population
- whether populations fluctuate extremely
What are the difficulties associated with identifying range size for the IUCN redlist?
- extent of occupation (area within range boundary) vs area of occupancy (occupied grid cells)
- measure different properties
- area of occupancy varies with spatial scale
What are the difficulties associated with identifying population size for the IUCN redlist?
- population size: number of mature individuals capable of reproduction
- but sex ratio/biases must be considered
- reintroduced individuals only counted after having successfully bred
What are the difficulties associated with identifying population number/fragmentation for the IUCN redlist?
- typically has to use habitat distribution data as little information on links between populations
What are the difficulties associated with identifying population trend for the IUCN redlist?
- over ten years or 3 generations
- observed, inferred or suspected in the past OR
predicted in the future
- e.g. endangered if decline > 50% and causes
unknown, continuing or not reversible
- often no direct data on population trend
- can use data on trends in habitat loss – if good
data on habitat selection available