species based conservation Flashcards
what are the three different approaches to conservation
1) species based e.g. CITES, assisted migration or building evolutionary resilience
2) landscape-scale conservation
3) Ex-situ conservation
what is meant by species based conservation
picking a species ad focusing on putting conservation methods to protect that species
outline the different processes for species based conservation
1) Assess species e.g. IUCN red list
e.g. Island foxes in California, pop declines 90-99% in 1990s
2) create species management plans
e.g. identify threats and work with stakeholders to implement the plan
3) implement plan
e.g. relocate golden eagles back to mainland, captive breed and release of foxes
4) continue monitoring
e.g. use of science and data, multiple organisations working together, presence of intact habitat
what is meant by the term stochasticity
having a random probability distribution or pattern which can be analysed such as variation in birth and death rates, changes in sex ratio or disease as a result of a small population
outline a case study which demonstrates the effect small populations have in relation to stochasticity
Ngorongro Crater lion in Tanzania consisted of 90 individuals in 1961 before crashing in 1962, since that time population peaked at 125 individuals in 1983 before collapsing to 34 as a result of small pop size, isolated location and disease resulting in bottle neck
outline how reintroductions impact environmental stochasticity
Przewalski’s horse present across a lot of Europe but went extinct in the wild in the late 1960s
they were reintroduced in the Mongolian Gobi desert and pops grew steadily before a severe winter caused pops to decline 60% from 2009-2010 showing effects enviro stoachticty has on isolated pops and that reintroduction sites should be spatially dispersed
what is meant by the term effective population and low effective population size
the number of individuals that contribute genes equally to the next generation; so a population may have a high number of individuals and appear well but only a small amount of those individuals are breeding = bad
a small population size results in a low effective pop size with less genes contributed to next generation decreasing genetic diversity
what factors cause a low effective population
1) age distribution (many individuals may be immature)
2) unequal sex ratio
3) reproductive skew (unequal breeding success)
4) bottlenecks and founder events
how does a small population size result in low genetic diversity
- Genetic drift is more likely to occur
- inbreeding more likely- causes reduced fitness (inbreeding depression)
what is an extinction vortex
a model which are used to understand the dynamics of and categorize extinctions in the context of their causes
e.g. small pop–> inbreeding genetic drift–> loss of genetic variability–>reduction in individual fitness and pop adaptibiltiy–> high mortality and low reproduction–>small pop–> extinction
what is meant by minimum viable population size
an estimate of the number of individuals required for a high probability of survival of a population over a given period of time = cross- species studies show for 90% survival MVP need to be around 3000-5000 individuals
outline a case study how a species exploring how low population numbers can go and be maintained
The relationship between initial population size (N) of bighorn sheep and the percentage of populations that persisted over time. Almost all populations with more than 100 sheep persisted beyond 50 years, while populations with fewer than 50 individuals died out within 50 years. Not included are small populations that were actively managed and augmented by the release of additional animals. (A, after L. W. Traill et al. 2010. Biol Conserv 143: 28–34. B, after J. Berger. 1990. Conserv Biol 4: 91–98.)
how do we measure population sizes
Census- count the number of individuals e.g. BTO breeding bird survey used 3000 individuals allocated 1km square to survey, recording birds seen and heat
capture- mark recapture
genetics- often used to conduct a census where you cant count individuals by calculating effective pop size using genetic data
what are the disadvantages of using a census to measure population size
time consuming
some species hard to detect
often not repeated over time
what knowledge is needed to produce effective conservation
1) where and when the species reproduces e.g. nesting sites
2) Habitat selection and requirements e.g. the wandering elephants of China in 2021
provide some examples of legal and physical protection needed for effective conservation
1) International protection e.g. CITES
2) National protection e.g. the wild life and country size act 1981
outline the wildlife and countryside act 1981 in the UK
- protects many bird species including nests and eggs, most mammals, amphibians, reptiles, wild plants and some invertebrates against killing/taking
- bans the release of invasive species
- includes regulation of some protected areas such as SSSIs
define the different terms; flagship species, umbrella species, keystone species/ecosystem engineers
flagship= species with charisma and grab the attention of public helping direct resources towards their entire ecosystem
umbrella= species which benefit other species e.g. wildebeest migration area is protected which also helps many other species living in that area
where can trade offs between conservation be seen
1) space and resources are limited e.g. the ideal habitat for one species is different from another such as sand lizards breed in sand dunes vs breeding birds in bushes and trees
2) human- wildlife conflict e.g. large predator conservation, they kill people and livestock , human presence must be considered when conservation planning
outline a case study which addresses accidental morality and human-wildlife conflict
1) Toads in the hole
- significant declines in common toads since 1980s
- part of this problem was drain holes in roads which acted as a large pitfall trap but essential for road drainage
- paired with engineers to produce better gully holes allowing toads to escape
