conservation of biodiversity A4.2

biological diversity definition

the variety of all life in all its forms

types of diversity

• ecosystem diversity

• species diversity

• genetic diversity

ecosystem diversity definition

Range of different habitats / number of ecological niches per unit area in an ecosystem

species diversity definition

• the different species on the evolutionary tree of life.

• (these species have varied body plans,internal structure, life cycles + modes of nutrition.)

genetic diversity definition

• variety in the gene pool within each species

• (there is variation between geographically separated populations + within populations)

biodiversity levels on earth

• number of species on earth is difficult to estimate. 

• However, biodiversity is probably higher now than it has ever been

biodiversity + mass extinction

biodiversity tends to rise gradually between mass extinction events

mass extinctions

• 5 mass extinctions in the past

• most recent : 66 million years ago. At the end of the Cretaceous period. → caused by asteroid colliding with earth

• previous mass extinctions were caused by : volcanic activity, major changes to atmosphere + global climate.

what does Anthropogenic mean?

due to human activities

3 case studies - Causes of anthropogenic species extinction

• Giant moa

• Caribbean monk seal

• European Bison

Giant moa - part of terrestrial megafauna -Causes of anthropogenic species extinction

• group of flightless birds native to New Zealand

• had height up to 3.6m and mass of 230kg

• New Zealand remained uninhabited by humans until the 13th century

• it then took less than 200 years for all species of Moa to be hunted to extinction

caribbean monk seal - marine mammal - Causes of anthropogenic species extinction

• only seal species native to central america

• declared extinct in 2008. last confirmed sighting in 1952

• monk seals were widely hunted for their blubber + meat 

• known for being non aggressive (easy to hunt) + sensitive to disturbance

• museum practices for collecting + displaying monk seals also lead to their extinction

european bison - Causes of anthropogenic species extinction

• home to the cold tundras of Britain + switzerland before the last ice age

• as climate warmed → Bisons disappeared due to other species dominating grassy landscapes which slowly became woodland

• in 2020 6 bisons were reintroduced in switzerland

anthropogenic causes of the 6th mass extinction

• habitat destruction

• invasive species

• pollution

• global climate change

why does habitat destruction + invasive species lead to extinction?

• habitat destruction - natural habitats destroyed for agriculture/building towns + cities.

• invasive species - alien species introduced to a ecosystem → drives native species to extinction due to predation, spreading of pests + diseases, competition for resources

why does pollution + climate change lead to extinction?

• pollution - chemical industries produce a vast range of substances that are discarded in the environment. (sources of pollutants: fossil fuels, agriculture, mining, oil extraction, pharmaceuticals)

• climate change - human activities cause rapid changes in temperature,rainfall + other climatic variables → species that cannot adapt quick enough/cannot migrate → go extinct

Causes of ecosystem loss

• agriculture

• urbanization

• overexploitation of natural resources

• mining + smelting

• water management

• drying of wetlands

• leaching

• climate change

overexploitation of natural resources + mining and smelting - ecosystem loss

• overexploitation of natural resources - gathering fuel, wood, hunting animals.

• mining + smelting - opencast mines destroy natural ecosystems completely. Smelting + disposal of waste from mines causes pollution + more damage. much of tropical rainforest have been lost due to mining.

water management + drying of wetlands - ecosystem loss

• water management - reservoirs can flood natural ecosystems. Extraction of water can greatly reduce river flow. (e.g colorado river no longer reaches the sea)

• drying of wetlands - swamps + other wetlands are drained for agriculture. Wetlands are also destroyed by diverting the water that flowed into them for human use

leaching - ecosystem loss

• washing off fertilizers into rivers lakes → eutrophication + algal blooms

• oligotrophic ecosystems (organisms are adapted to low nutrient concentrations) are lost

ecosystem loss case studies

• mixed dipterocarp forest of southeast asia

• river floodplain in switzerland

mixed dipterocarp forest of southeast asia - ecosystem loss case study

• causes:

• logging since 1970’s due to high amount of timber per hectare.

• land conversion to palm oil plantations

• consequences

• changes in forest structure reduce biodiversity

• peat in the area decomposes and releases CO2 → contributes to global warming

river floodplain in switzerland - ecosystem loss case study

• causes

• increased urbanization

• drainage

• consequences

• intensifies flood events

• loss of natural flood retention area

surveys - evidence for biodiversity crisis

surveys need to be repeated to provide evidence of change in species richness + evenness

ways to gather evidence for biodiversity crisis

• determining population size in an area over years

• range of species in an area

• richness + evenness of biodiversity in an ecosystem (simpson’s diversity index)

• number of threatened species within a taxonomic group

• citizen science projects

• extent of degradation of an ecosystem

• diversity of a species in an ecosystem

sources of evidence for biodiversity crisis

• governmental sites which gather and collect evidence by monitoring.

• state of biodiversity is assessed and reports are periodically produced

current causes of biodiversity crisis

• human population growth

• hunting + other forms of overexploitation

• urbanization

• deforestation

• clearance of land for agriculture → loss of habitat

• pollution

• spread of pests + diseases

• invasive alien species due to global transport

types of conservation of biodiversity

• In-situ conservation

• Ex-situ conservation

• rewilding

• storage of germ plasm

why are there so many type of conservation of biodiversity

• no single approach will be enough

• measures must be selected according to target species or ecosystems + the causes of biodiversity loss 

In situ conservation description

• conservation of species in their natural habitat

• (designated area with controlled access by humans + poaching prevention, removal of alien species, reintroduction of locally extinct species, control of population sizes. )

• e.g national parks, wildlife sanctuaries, biosphere reserves

strengths + weaknesses of in situ conservation 

• strengths

• keeps organisms within natural food webs

• allows organisms to stay where they are adapted to

• maintain normal behaviours

• weaknesses

• may not be efficient

• might lead to decrease in genetic diversity (control migration)

• greater maintenance + costs involved

ex situ conservation description

• perseveration of species outside their natural habitat

• involves critically endangered species where urgent intervention is required

• e.g zoos, botanical gardens 

strengths + weaknesses of ex situ conservation

• strengths -

• greater control over conditions

• less competition 

• continuation of species that permanently lost their habitat

• longer lifetime

• weaknesses -

• doesn’t help to prevent destruction of the environment

• limited genetic diversity as species are within a shallow gene pool

• species raised in captivity are less likely to be re-introduced back into the environment

rewilding description

• return of degraded ecosystems to as a natural state as possible

• recovery can be rapid and balance is then maintained by natural ecological processes

long-term storage of germ plasm description

• seeds of plants are stored dry in seed banks at low temps so they can maintain vitality for long periods

• animal germ plasm is stored at very low temperatures (-20 — -200) in tissue banks

The EDGE of existence program criteria

• Evolutionary Distinct - does the species have few or no close relatives? member of a very small clade?

• Globally Endangered - is the species likely to become extinct because all remaining populations are threatened.

EDGE species

• species that fit both EDGE criteria

• listed + targeted for intense conservation efforts.