Topic 3 - Biodiversity

Biodiversity

amount of biological or living diversity per unit area

types of biodiversities

• species diversity

• habitat diversity

• genetic diversity

why is genetic diversity important?

• better chance that some members of the species will be resilient and survive environmental change (caused by disease, climate change and pollution)

• Low genetic diversity (often caused by small populations) causes inbreeding which makes the genetic make up of the population more uniform. This means that any flaws or disabilities within that population will become more common 

• Extinction is frequently preceded by a drop in genetic diversity

• Once lost, genetic diversity is almost impossible to regain

• If something humans rely on is struck by disease then genetic diversity increases the chances of finding alternatives that are disease free

connection between habitat diversity and genetic diversity

• High habitat diversity gives different areas for populations of species to spread into

• Separation leads to greater variations in the gene pools

connection between habitat diversity and species diversity

• High habitat diversity gives a wide range of spaces for animals to adapt to and move in to

• results in higher species diversity

connection between genetic diversity and species diversity

High genetic diversity increases species adaptability and can lead to speciation hence higher species diversity

connection between species diversity and habitat diversity

High species diversity of plants so higher habitat diversity

species diversity

• variety of species per unit area

• is the number of different species in a given area taking into account the richness and evenness of the species

• richness = measure of the number of different species in an area, more species means a richer environment

• ​Evenness = the relative abundance of the species

habitat diversity

is the range of different habitats in an area

genetic diversity

variation of genes within the genetic pool of a population of a species

succession

the process by which the mix of species and habitat in an area changes over time

relationship between ecosystem stability / diversity / sucession / habitat

•Each stage/sere of succession creates a deeper and nutrient-rich soil = allowing larger plants to grow

•This increases the habitat diversity = greater species and genetic diversity (more complex food webs) = greater stability

•more complex food webs = greater diversity, so more stability if one organism goes extinct

factors that lead to loss of diversity

• natural hazards

• loss of habitat

• fragmentation of habitat

• pollution

• agricultural practices

• overexploitation

• introduction to non-native species

• spread of disease

factors that determine biodiversity

• age of the area

• environmental stability

• range of habitats

age of the area biodiversity

• Older areas tend to have higher biodiversity

• This is because longer time-span allows organisms to diversify more and drive greater speciation

environmental stability biodiversity

• Some areas of the planet have experienced environmental disturbances (volcanic eruptions, earthquake or floods) 

• or climatic disturbances (glaciations or drought) 

• these may destroy large numbers of species These areas have had less time for colonisation and species adaptation

range of habitats biodiversity

A wide range of habitats will allow the organisms to move into new habitats and ecological niches, therefore evolving and driving speciation

wide range of habitats types

• Greater vertical extent of the vegetation

• Altitudinal variation

• Latitudinal ranges

• Variation in rock and soil types

benefits of biodiversity

• natural capital

• the balance of atmospheric gases, clean air, the water cycle, climate regulation, soil formation and protection and pollution breakdown and absorption

• physical/mental value

• maintains genetic diversity and thus is important to the continuation of evolution
   

fragmentation of habitat

large area is divided up by roads / other contruction

agricultural practices

• mono-cultures = growth of only 1 species pf crop over a large land area

• pesticides

factors that make species prone to extinction

• limited distribution

• small population size

• habitat specialists

• low reproductive capacity

• poor competitors

• large mammals

• valuable products

• altruistic species

• position in foodchain

limited distribution explain

island species are unable to adapt to changing condition

small population size explain

smaller genetic diversity

habitat specialists explain

organisms that are dependent

valuable products explain

the value that animals have

altruistic species explain

pack creatures survive better in groups

red list

•Categorizes organisms by “risk of extinction”

•Guides conservation efforts

factors used to determine species red list conservation status

• Population size

• Reduction in population size

• Numbers of mature individuals

• Geographic range and degree of fragmentation

• Quality of habitat

• Area of occupancy

speciation

the process by which new species form through biological processes

significance of plate movement on biodiversity

•important in generating new and diverse habitats

•forms barriers, also bridges between previously separated plates (provides opportunities for species to spread)

types of crust

• continental crust

• oceanic crust

continental crust

• older

• lighter

• cannot sink and is permanent

oceanic crust

• younger

• heavier

• can sink and is constantly being destroyed and replaced

4 types of plate movement

• Constructive margins

• Destructive margins

• Collision margins

• Conservative margins

constructive margins

•Two plates move away from each other.

•Molten rock (magma) rises to fill any possible gap and forms oceanic crust

•The Atlantic Ocean widens every year

destructive margins

• Occur where plates consisting of oceanic crust move towards plates of continental crust.

• The oceanic crust is forced downwards, to make subduction zones

• The increase in pressure can trigger earthquakes

• Newly formed magma rises to the surface to form volcanoes

Collision margins

• When two land masses meet the two crush together at what is known as a collisional boundary.

• They crumple and fold

• The result is a mountain range

Conservative margin/boundary

• Fault

• breaks the Earth’s crust.

• Crust is neither created nor destroyed.

• Earthquakes occur along these boundaries and deep (sea) trenches are found here

fault

A place where two plates slip past each other, moving in opposite directions

TRF

Hotspots of biodiversity

TRF characteristics

• usually high numbers of endemic species

• they are threatened areas, where 70% of the habitat has been lost

• tend to have large densities of human habitation nearby

• 50% of all species of plants and animals live in TRF

endemic species

a species that is uniquely found in one part of the world

Layering of rainforests

• The emergent layer = highest layer and consists of trees that extend beyond the general canopy

• The canopy level = dense and significantly reduces light penetrating further into the forest

• The understory layer = below the canopy layer consisting of shrub plants and tree saplings

• The forest floor or ground layer = receives less than 2% of the light, green plants are limited in number. Humidity is very high due to the limited air movement and high evaporation rates in the layer

Forest Floor/shrub layer explain

dark with very little vegetation between the trees. It receives around 1% of the available solar power

under canopy explain

receives limited sunlight (2-5%)

canopy explain

• where the upper parts of most of the trees are found

• about 20 to 40 meters tall

• Gets about 80% of the light

emergents explain

• the tops of the tallest trees in the rainforest

• photosynthesis occurs in the upper layers

human impact on rainforests

• Loss of habitat

• Loss of species/genetic pool

• Nutrient cycle is interrupted

• Reduced soil fertility

• Soil erosion (greater overland flow)

• Decreasing evaporation/transpiration = reduced rainfall = higher temperatures

causes of human impact on rainforests

• Deforestation/Logging

• Commercial agriculture

• Infrastructure

• Clearing for cattle

• Government land policies

• Shifting cultivation

shifting cultivation

an agricultural system in which plots of land are cultivated temporarily, then abandoned and allowed to revert to their natural vegetation while the cultivator moves on to another plot

what can be used to calculate species diversity

simpsons index

Simpson index formula

D = N(N-1) / sum of n(n-1)

D

diversity index

N

total number of organisms of all species found

n

total number of individuals of the species of interest

genetic variability

describes the variation of genetic characteristics

evolution

the change in the genetic composition and therefore the heritable traits of a population over successive generations

causes of evolution

• mutations

• natural selection

what causes speciation

• evolution

• isolation (geographical, temporal, behavioral)

types of isolation and what they are

• geographical = Populations are physically separated and can no longer interbreed

• temporal = Populations live their lives at different times of the day and so do not meet to breed

• behavioral = have different mating rituals

mechanism of natural selection

• Within a population of one species, there is genetic diversity (variation)

• The offspring of fitter individuals may inherit the genes that give them that advantage

• Due to natural variation, some individuals will be fitter than others and therefore have a comparative advantage

• Fitter individuals are more likely to survive long enough to reproduce more successfully than individuals who are less fit

mass extinction

sudden global decrease in the number of species over a relatively short period of time

Background or normal extinction

the standard rate at which species go extinct

how do mass extinctions lead to biodiversity?

• Mass extinctions remove large numbers of species, creating vacant ecological niches

• This allows for succession, where pioneer species begin colonizing and ecosystems rebuild

• With reduced competition and new resources available, adaptive radiation occurs

• surviving species evolve into new forms to exploit the empty niches

• Over time, this leads to the emergence of more diverse species and higher biodiversity than before

example of a mass extinction and how it lead to biodiversity

• The K-T Mass Extinction

• 66 million years ago

• caused by asteroid impact

• wiped out 75% of species, including non-avian dinosaurs

• This left many ecosystems open for mammals, which had previously been minor players

• Mammals underwent adaptive radiation, evolving into diverse forms (primates, whales, bats)

• Over millions of years, this led to greater biodiversity, including the eventual rise of humans

ICUN red list

range of criteria to objectively evaluate whether a species is under threat

categories = least concern, vulnerable, endangered, critically endangered

criteria used to determine status of species on red list

• population size (number of mature individuals)

• population size reduction

• geographical range (extent of occurrence and area of occupancy

• extent of habitat fragmentation

• quality of habitat

• probability of extinction

• degree of specialization (restricted diet)

• trophic level (organisms up the food chain are exposed to higher levels of pollution due to bio-accumulation and biomagnification)

difference between extent of occurence and area of occupancy

• The area of occupancy is where the species can normally be found

• The extent of occurrence is the boundary that can be drawn around the sites the species occupies

biological hotspot criteria

• It must have at least 1,500 vascular plants as endemics

• it must have a high percentage of plant life found nowhere else on the planet

• It must have 30% or less of its original natural vegetation

why are biological hotspots important?

• allows conservation efforts to be focused in areas where it can protect the highest numbers of species

• 34-35 global biodiversity hotspots, mostly located in the tropical rainforest

• occupy only 2.3% of Earth’s land area but contain approximately 50% of the earth’s endemic plant species and 42% of all terrestrial vertebrates

rainforest characteristics

• Rainforest contain more than half the world’s plant and animal species.

• high level of primary production supports an many species

• old biomes, have developed into climax communities with high levels of biodiversity 

why are nutrient cycles in the tropical rainforest short?

• Nutrient levels in the soil are low as nutrients are leached out by the continual rain

• Nutrients are mostly held within the biomass especially the root mats

• Therefore, removal of trees can cause nutrient levels within the ecosystem to decline rapidly

important groups of species in conservation

• umbrella species

• keystone species

umbrella species (are are they and why are they important to conservation)

• these are often large species requiring large habitat areas

• Protecting the habitat of this species also protects the habitats of other species

• The Giant panda is an umbrella species

keystone species (are are they and why are they important to conservation)

• control population of herbivores

• herbivores population can increase which leads to overgrazing of vegetation

• this destroys the entire ecosystem and habitat of other species

In-situ conservation

protection of species in their habitat

Ex-situ conservation

• improves the probability of survival of the species by taking them out of their habitat and breeding them in captivity

• with the intention of re-introducing them back into the wild in the future

advantages of in-situ conservation

• protects species in their natural habitat

• preserves entire ecosystems

• cheaper than ex-situ

• allows for ecotourism

disadvantages of in-situ conservation

• may not be enough for critically endangered species

• large habitats are difficult to monitor and protect

• high enforcement

advantages of ex-situ conservation

• increase numbers, decrease extinction

• learning opportunity of the species

• use of zoos can educate the public

• gene pool can be enhanced

disadvantages of ex-situ conservation

• requires financial resources

• does not adress habitat loss

• species may not survive in wild

• species may be more suseptable to disease

• ethical concerns over captivity

zones of protected areas

• Core area

• Buffer zone

• Transition zone

core area

natural environment under protection

buffer zone

• found between the core area and transition zone

• to minimise any harm in this area, use is limited

• scientific research, training and education

• This area acts as a barrier to protect the core area from human activities in the transition zone

transition zone

• where there is sustainable use of natural resources

• This area can be affected by human activities outside the transition zone