IB ESS - Topic 3. Biodiversity

environmental pressures

the factors (abiotic or biotic) in an ecosystem which put pressure on an organism's survival and increase competition (whether inter-species or intra-species)

biodiversity

range/# of organisms found in a single place

richness of biodiversity vs. evenness of biodiversity

richness: # of species

evenness: if habitat has similar #s of each species

biodiversity is explored at the following levels:

species diversity, genetic diversity, and ecosystem (habitat) diversity

variation

the differences, either physical, phenotypic or genetic, between individuals of a species

species diversity

the variety of species within a given area, habitat, or region. includes # of species and # of individuals of each species

genetic diversity

the range of genetic variation present in a gene pool or population

habitat diversity

# of different habitats per unit area that a particular ecosystem/biome contains. if diversity inc. in habitat, it'll most likely lead to an inc. in the other 2.

Simpson's Diversity Index formula

Simpson's Diversity Index lowest biodiversity:

1

origins of biodiversity

- came from evolutionary processes

- Darwin "On the Origin of Species" 1859 outlined natural selection, a theory of evolution of species

4 stages of natural selection

1. overproduction

2. genetic variation within that oversized population

3. struggle to survive; competing for resources

4. differential reproduction

random genetic mutations

the small differences which may occur in an organism as a result of reproduction - these small changes may add up to create variation

hotspots

an area of high biodiversity (which is under threat from human activities)

endemic species

the species which only occur in one specific area

speciation

the evolutionary process by which reproductively isolated biological populations evolve to become distinct species

evolution

the process by which a species may adapt to environmental pressures through natural selection of favourable variation caused by random genetic mutations - over thousands of generations

natural selection

the greater chance of passing on of genes by the best adapted organisms due to environmental pressures. Their favourable traits are then passed on to new generations

geographical isolation

the separation of populations of a single species - often leads to speciation if populations cannot interbreed for a very long time

physical barriers

e.g. a mountain, ocean or separation of lakes

land bridges

a connection between land masses - often as a result of lowering sea levels e.g. the Bering Straits

continental drift

the movement of the tectonic plates by around 1cm a year causing the change in shape and location of continents

lithosphere

the Earth's crust - the rocky part of Earth

Gondwana

the land mass made up of Africa, New Zealand, Australia and South America, India, Arabia and Antarctica millions of years ago - separated millions of years ago

background extinction rate

the natural rate of extinction of species - around 1 species per million species per year

extinction

the complete loss of a species from Earth - no more individuals of that species exist

mass extinctions

an extinction rate far greater than background extinction rate

factors that cause mass extinctions

tectonic plate movements

super-volcanic eruption

climate changes (drought, ice age, etc)

meteorite impact

Holocene extinction event

the 6th mass extinction occurring for the last 10,000 years, however, much faster in the last 100 years - generally agreed to be as a result of human activity

5 major causes of species decline

habitat destruction/degradation/fragmentation

invasive species

-pollution

-human population growth

-overexploitation

characteristics of species vulnerable to extinction

K-strategist, specialized niche, feeds at high trophic level, rare, commercially valuable

critically endangered species ex.

tiger

extinct species ex.

dodo

recovering species ex.

bald eagle

weedy species

the species (generally plant or animal) which are able to survive the environments we create e.g. urban rats, domesticated animals

Living Planet Report

a report produced by the Worldwide Fund for Nature (WWF) creates on the state of the world's ecosystems

conservation

the act of preserving nature - attempting to save habitats, species and biodiversity in general

approaches to conservation

habitat conservation

species-based conservation

mixed approach

Species based conservation

pros/cons

focuses on conserving high profile, charismatic species to catch public interest

pro: saving a species means preserving its habitat, benefiting all the other organisms in that habitat

con: favors charismatic organisms, less successful in saving less famous species. also a species can be preserved in zoo, not preserving the habitat

habitat conservation (protected area) criteria

edge effects: edge may have different abiotic factors attracting species not found deeper in the reserve.

size: 1 large > several small (so we can have large pops and more biodiversity and protect large vertebrates/top carnivores, also less edge effects)

shape: circle = less edge effects and poaching (harder to get to the center)

buffer zone: minimizes disturbance

close>isolated

clumped>spaced out to allow dispersion and recolonization

corridors: allows migration

2 approaches to biodiversity conservation

in situ (within habitat)

ex situ (outside habitat)

in situ conservation + ex.

within habitat

protects the plants and animals

ex. national parks, sanctuaries, reserves

ex situ conservation ex.

gene banks, seed banks, zoos, botanical gardens, etc.

pros/cons of zoos (ex situ)

pros:

education, controlled environment, genetic monitoring, improved

protected area ex.

Costa Rica (successful~)

2/3

the proportion of living species which are found in tropical rainforests

threats to tropical biomes

thin, nutrient poor soil; difficult to re-grow once cleared

etc....

current extinction rates

approx. 100 species per million species per year

ecosystem complexity

creates stability and resilience to change in an ecosystem - there are many pathways for energy flow

limiting factors

environmental conditions that limit the growth, abundance, or distribution of an organism or a population of organisms in an ecosystem - when there are few of these, biodiversity is likely to be high (and vice versa)

inertia

the ability of an ecosystem to resist change and maintain equilibrium when subjected to a disruptive force

natural hazards

naturally occurring events which may have a negative impact on the environment

habitat loss

the major cause of loss of biodiversity

habitat fragmentation

when a large area of habitat is broken into many smaller areas, often physically divided by roads, towns, factories, power lines etc - leads to the loss of biodiversity

overexploitation

the overuse of a resource to the point that is has a negative impact on the ecosystem e.g. deforestation

introduction of non-native species

when a species which is not naturally occurring in an ecosystem is introduced and may out-compete the native species - this may lead to a loss of biodiversity e.g. rabbits, cane toads, red foxes, camels in Australia

lungs of the Earth

rainforests - they are called this because they are thought to produce around 40% of the oxygen that animals breath

low genetic diversity

caused by small populations or declining diversity - makes a species prone to extinction as they may not be able to adapt to change

low population density

some species need a large area to hunt - if there are only a few organisms over a large territory this may make them prone to extinction, especially if habitats become fragmented

low reproductive potential

reproducing slowly and/or infrequently - this makes a species prone to extinction as it may take a long time for a population to recover its numbers

seasonal migration

the movement between different areas at different seasons - this makes a species prone to extinction as they rely on more than one habitat - if one is destroyed, they will not survive

poor dispersers

a species which cannot move easily to new habitats - this makes them prone to extinction - for example plants which rely on a slow dispersal of seeds, flightless birds of New Zealand

specialised feeders

a species which requires a specific food and cannot eat others e.g. giant pandas eat bamboo shoots, koalas eat eucalyptus leaves - this makes them prone to extinction if their food source becomes scarse

minimum viable population size

the lowest number of individuals of a species needed for a population to be able to recover - if a population is lower than this number, they may become extinct

govt. vs. non-govt. methods of biodiversity conservation

media:

- g: media liaison officers prepare + read written statements

- ng: use footage to gain attention

speed:

- g: usually slow, depends on consensus

- ng: can be fast

political diplomatic constraints:

- g: considerable; often hindered by political disagreement, ESPECIALLY if intl.

- ng: unaffected; can even be illegal

enforceability:

- g: agreements + laws can lead to proseceution

- ng: no legal power; just uses persuasion and public opinion to pressure govts.

IUCN

The International Union for the Conservation of Nature and Natural resources - often known as the World Conservation Union

made up of government agencies, states, non-governmental organisations (NGOs) and scientists and experts - their goal is to conserve nature and increase sustainability of resource use

Outline, giving reasons, two factors used to determine a species' Red List conservation status.

population size: population must be large enough for genetic diversity so population remains viable

quality of habitat: even if a species is not directly under threat, if its habitat is being reduced/degraded this will indirectly have an effect on the species;

UNEP

United Nations Environmental Program

Explain how human actions can reduce species diversity in two named ecosystems you have studied.

modern agribusiness in temperate grasslands of Prairies, USA:

pesticides can kill all insect species not just the pests being targeted

cyanide fishing in tropical waters off the Philippines:

reefs are biological hotspots, cyanide kills many species directly

Evaluate the importance of species-based conservation and protected areas in the preservation of biodiversity for future generations.

species-based conservation:

can successfully preserve a species in zoos, but high maintenance costs in zoos.

protected areas:

protects the whole ecosystem/interrelationship so long-term survival is more likely, but requires sufficient funding/protection to ensure not disturbed

Explain how human wellbeing is threatened by the loss of biodiversity.

more diverse environment = more likely to have more resources

areas of high diversity are more aesthetically pleasing than areas of low diversity, thus better places to live

low biodiversity reflects poor environmental conditions

Evaluate the role of local support, government agencies and research in the protection of a named protected area you have studied.

Costa Rica.

local support: their economic future and the future of the park are linked

govt:

punish poachers

research:

identifies new hazards and new goals;

Evaluate species based conservation as an approach for preserving biodiversity and suggest why trophy hunting (i.e. hunting animals for sport) may represent an acceptable method of achieving this goal.

species based conservation:

good because it concentrates on one or two key species, but may result in a species being conserved artificially outside its habitat, thus the organism and not the habitat it belongs in is protected.

trophy hunting:

managing habitat for "game" may have benefits for many other species

Discuss the causes and timing of past extinction episodes within the fossil record.

Describe the case history of one species that is endangered and one species that was endangered but has now been successfully removed from the endangered list.

tiger (endangered)

Endangered because of habitat (forest) loss due to agriculture

Loss of food source as traditional food source is being used by humans

Hunting for hides, trophies, medicine

Destroyed because regarded as a nuisance / pest

Ecological role is as a top carnivore

Loss would lead to an increase in herbivorous mammals

Ethical issues surrounding loss (rights of future generations, right of species)

Human guilt of allowing this to happen

Crocodile (now removed from endangered list)

Was endangered due to excessive hunting for skins, meat & trophies

And due to threats to humans & livestock

And due to habitat degradation (loss of water quality)

Ecological role is top carnivore

Loss would lead to imbalance in food pyramid

No longer endangered because of education (no longer seen as 'evil')

Ban on hunting

Controlled culling / hunting of certain crocodile species now being considered

Evaluate the strengths and limitations of zoos in conserving endangered species and justify your personal viewpoint.

Arguments for Zoos

Individual organisms are protected in a controlled environment

Education of public through visits may make them more likely to support conservation campaigns

Genetic monitoring can take place

Captive breeding enables higher rates of reproductive success

Number of offspring surviving adulthood is higher so species numbers increase more effectively

Studying species so understanding improves, helping management outside zoos

Arguments against Zoos

Ethical arguments against keeping animals in captivity for profit

Conserving species is just used as an excuse

Poor conditions or treatment in zoos leading to physiological and psychological problems for animals

Captive animals unable to adapt to life back in wild

Small genetic pool

Personal justification (needs to be more than just arguments for or against)

CITES

Convention on International Trade in Endangered Species

UNDP

United Nations Development Program

WWF

World Wide Fund for Nature

WRI

World Resource Institute

IGO

Intergovernmental organizations

GO

Governmental organizations

NGO

Non-govedrnmental organizations

large body

due to the 10% rule, it is much more difficult for big organisms to find enough food - this makes them prone to extinction e.g. wolves, tigers