Report 7 Flashcards
‘Keystone Species’ was introduced by
Robert T. Paine in 1969
Two basic criteria of keystone species have been proposed by Mills et al.
i. The presence of keystone species is crucial in maintaining the organization and diversity of their ecological communities.
ii. These species are exceptional, relative to the rest of the community, in their importance.
examples of keystone species:
- sea otters (Enhydra lutris) and sea urchins (Strongylocentrotus spp.) feed over kelps
- Solenopsis geminate (Fire ants) exclusion increases the number of arthropods which are harmful to agriculture.
- Humming bird pollinators.
- Terborgh proposed the palm nuts, figs and nectars as keystone resources because of their extreme significance for fruit and nectar eating species of tropical forest like the primates, squirrels, rodents, and many birds.
examples of keystone species:
- Caster canadensis (North American beavers) make dams which can change hydrological and biogeochemical factors of the region to alter the productivity.
- Cornitermes cumulans (Brazilian termites) make bulky, rich and distinctively designed mounds which has wide range of obligate users.
- Sea urchins grazing prevents the transition from encrusting algae dominated community to a large, fleshy algae dominated one.
*Thomomys bottae (Pocket gophers) maintain mountain meadow communities.
Threats to Biodiversity
- Escalating Extinction Rate
- Irreversible Loss
- Climate Change as a Threat
to standardize terminology for threats to biodiversity, making it easier to compare and generalize data across ecosystems. It includes threats from alien species, genetic material, and interactions among native species
threat classification system
The IUCN classification distinguishes between ______________, such as geological events, climate changes, and severe weather, and direct threats to biodiversity.
abiotic threats
The World Conservation Union–Conservation Measures Partnership (IUCN-CMP) proposed a ________________ that contribute to biodiversity loss, defining stresses as degraded conditions resulting from direct threats.
classification of stresses
Biodiversity faces severe threats from a combination of anthropogenic and natural factors
multifactorial threats
A comprehensive classification of direct threats to biodiversity proposed by Salfasky et al.
- residential and commercial development
- agriculture and aquaculture
- energy production and mining
- transportation and service corridors
- biological resource use
- human intrusions and disturbance
- natural system modifications
- invasive and problematic species and genes
- pollution
- geological events
- climate change and severe weather
evaluated tens of thousands of species worldwide and categorized them as threatened with extinction. This included species classified as critically endangered, endangered, and vulnerable. Several taxa, including amphibians, corals, conifers, mammals, and birds, were reported to be at risk
2012 IUCN Red List
The stress classification for biodiversity proposed by Salafsky et al
Ecosystem / community stresses
Ecosystem conservation
Ecosystem degradation
Indirect ecosystem effects
Species stresses
Species mortality
Species disturbance
Indirect species effects
Threats to global biodiversity
Habitat loss through degradation and fragmentation
Population growth and Poverty
Over exploitation of natural resources
Invasive species
Climate change and Pollution
Disease
Weak enforcement of law
Background extinction
Stochastic events and Hunting for food
Habitat is lost through conversion to agriculture and housing
when there is no reaso nable doubt that the last individual has died
extinct
it is known only to survive in captivity, or as a neutralized population outside its historic habitat.
extinct in the wild
it is facing high risk of extinction in the wild in immediate future.
critically endangered
it is facing very high risk of extinction in the wild in near future
endangered
it is facing very high risk of endangered in the wild in near future.
vulnerable
it is likely to become endangered in near future.
near to threat
A taxon with lowest risk. These are the widespread and abundant taxa.
least concern
there is inadequate information to make any direct or indirect assessment of its risk of extinction.
data deficient
it has not yet been assessed against the above criteria.
not evaluated
Conservation strategies are broadly classified into two categories:
in-situ conservation (conserving species in their natural habitats)
ex-situ conservation (conserving species outside their natural habitats)
defined as “the conservation of ecosystems and natural habitats and the maintenance and recovery of viable populations of species in their natural surroundings and, in the case of domesticated or cultivated species, in the surroundings where they have developed their distinctive properties”
In-situ Conservation
