3.2 - Human impact on biodiversity Flashcards
Habitat loss
The major cause of loss of biodiversity due to human activities
Direct threats (examples)
Target individual species
* overharvesting, poaching, illegal pet trade
Indirect threats (examples)
Broad actions that impact many species
* habitat loss, climate change, pollution, invasive alien species
How has overharvesting and hunting affected biodiversity?
- Hunting animals for food, medicine, souvenirs, sport
- Depleting pop. numbers
- threatens long-term survival and reproduction
- e.g. cod fish in North Atlantic (1990s - 90% loss)
How has poaching affected biodiversity?
- Illegal hunting & capture of wildlife
- trafficking worth billions
- e.g. elephants killed for ivory tusks
How has illegal pet trade affected biodiversity?
- trading exotic birds, baby primates, reptiles
- threatens ongoing species conservation efforts (like International Endangered Species protection)
- disrupts natural population dynamics
How has habitat loss affected biodiversity?
- degradation of natural environments
- agriculture practices replace diverse landscapes, monoculture replaces complex ecosystems
How has climate change affected biodiversity?
- alters temperatures and percipitation patterns (biomes shift up by 1km/year)
- disrupts species migration and breeding cycles
- frequency of extreme weather
- can’t adapt
How has pollution affected biodiversity?
- damages habitat and kills organisms
- reduces population numbers during biomagnification of plastics which disrupts ecosystem balance
Process of bioaccumulation of microplastics (4)
- Sorption: polymers attract pollutants, large surface area increase sorption
- Release: residence times determines pollutant release potential, down a concentration gradint
- Bioaccumulation
- Toxicity
Invasive alien species
Non-native species that have colonised a new area to the point of damaging the surrounding environment (major threat)
How have invasive alien species affected biodiversity?
- compete for limited resources
- displace native species
- induce new diseases and parasites
- alter existing ecosystem dynamics
Direct threat
One made towards a certain species or part of an environment with knowledge of its harmfulness
Indirect threat
An event which produces a series of consequences that harm a species or ecosystem
5 human factors affecting ecosystesm
- deforestation
- desertification
- invasive species
- overharvesting
- global warming
Example of invasive species (plant)
Water Hyacinth
Origin: Amazon Basin, Brazil
Introduced to: Africa, Asia, North America
Impact: Chokes waterways, reduces water-oxygen levels, blocks sunlight for underwater life
Example of invasive species (animal)
Brown tree snake
Origin: Indonesia and Papua New Guinea
Introduced to: Guam
Impact: caused extinction of several native bird species, disrupted entire island ecosystem
Factors used to determine the conservation status of a species (name 3)
- population size
- degree of specialisation
- distribution
- reproductive potential and behaviour
- geographic range an degree of fragmentation
- quality of habitat
- trophic level
- probability of extinction
IUCN Red list
- LC - widespread and abundant
- NT - some population declines
- VU - high risk in the wild in the medium-term future
- EN - very high risk, rapid decline
- CR - extreme risk, small populations
- EW - no longer exists in natural habitats
- EX - no longer exists anywhere
3 Conservation stati
Government perspectives (conservation in Brazil)
NGOs (WWF, habitat protection)
Individual perspectives (activism)
Extinc animal case study
The Dodo
Range: island of Mauritius
Habitat: dry, lowland forest
Niche: mostly herbivorous bird
Threats: hunting and trapping during European colonisation (did not try to escape) - hunted for food, eggs eaten by pigs
Conservation: last known dodo killed in 1662
Endangered species case study
Rafflesia - parasitic plant, smells like rotten flesh to attract insect pollinators
Range: Indonesia, Sumatra
Habitat: tropical rainforest, eclusively on vines in Tetrastigma
Niche: single-sex plants must flower simultaneously
Threats: habitat loss from logging and deforestation, impacts of ecotourism, use in traditional medicine
Conservation: sanctuaries, “Save Rafflesia” campaigns, monitoring programs
Recovered species case study
Golden lion Tamarin - small monkey
Range: tiny
Habitat: rainforest canopy, Amazon
Niche: omnivore, prey to large cats and birds of prey
Threats: only 2% of native habitat remains, severely fragmented population, poaching of $20,000 yearly, high predation, unreliable food source
Conservation: captive breeding in zoos for 40+ years, 150 institutions aim to increase genetic diversity, 30% success rate
Tragedy of the commons
Possible outcomes of the shared unrestricted use of resource, with implications of sustainability and the impacts on biodiversity
