A4.2 - Biodiversity

3 different levels of biodiversity

Genetic diversity

• all the different alleles in a population within a species: gene pool

  • smaller = promote inbreeding

  • bigger = more diversity

• why important: allows evolution/natural selection needs variation/decrease risk of extinction during environmental challenges

Species diversity

• # of different species (richness)

• # of each species (abundance)

• Tropical rainforest has more species richness compared to arctic tundra

• more equal proportion of species = more abundance = more species diverse

Ecosystem diversity

• ecosystem: community of organisms in a specific localised area, interacting with each other + abiotic environment

• ecosystem diversity: # of different ecosystems found in a particular geographical area

How has biodiversity changed over time

• large scale: increased - more and more species evolving = vacant niches

• short scale: decreased maybe

• why so much variation: undiscovered areas + areas discovered might be hard to differentiate - mostly bacteria is undiscovered

Lumpers vs splitters

Lumpers: groups of scientists who decide to take closely related organisms and group together

Splitters: seperate organisms which have differences into even smaller groups

Anthroprogenic extinction + reasons for this extinction

Anthropogenic extinction: the extinction of species caused by human activities -currently ecosystem and biodiversity loss is attributed to this

• Overharvesting

• Havitat destruction

• Invasive species

• Pollution

• Global climate change

CASE STUDIES EXTINCTION

Splendid poison frog

• Causes of extinction: deforestation, habitat degredation, logging + construction in habitat

• Why vulnerable: fungal disease, small geographic range

Tasmanian wolf/tiger

• Causes of extinction: intensive hunting, those that remained competed with dogs, habitat loss, disease wiped out

• Why vulnerable: limited prey, small, not very fast, not strong jaw

Ecosystem loss

Ecosystem loss: the degradation or complete disappearance of an ecosystem (community of organisms in a specific localised area, interacting with each other + abiotic environment)

Reasons:

• Urban sprawl

• Fragmentation of habitats

• Intensive land use (construc4ted areas increased more than 30%

• In mountaineous regions: intensive agriculture, water/leisure infrastructure (ski facilities)

• Building densification

• icnreasing use of pesticides, fertilizers, other pollutants = effect aquatic habitats

• Eutrophication

• invasive species

Ecosystem losses DIPTEROCARP

Loss of mixed dipterocarp (keystone species) forest in Southeast Asia

• Why essential for exosystem?

  • support other forms of life

  • roots hold soil

  • lock up large amounts of carbn which helpts fight climate change

• Cause?

  • Highly prized for timber + extensively felled (make furniture)

  • Cleared for palm oil plantations

• Knock on effects?

  • Aleady endagered animals (elephants/orangutans) lose homes

  • To clear forests they are burned - releasing carbon dioxide into atmosphere (climate change + Borneo)

Ecosystem losses CORAL REEFS

Loss of coral reefs

• Why essential for ecosystem?

  • Sustain food webs + protect coastline from erosion/storms

  • Sources for new medicines

• Cause?

  • Pollution: fertiliser run off, ot water from power plants, rubbish, plastic, oil spills

  • Overfishing

  • Coastal development

  • Unsustainable tourism
    Climate change rising ocean temperature + ocean acidification due to increased absorption of co2

    • Causes corals to expel algae - leading to bleaching of the coral reefs

• Knock on effects?

  • Affects other species that depend on reefs

Why is CH particularly vulnerable to decrease in biodiversity

• 9 million inhabitants concentrated in 2/3 of territory

• Small

• Densely populated with lots of transportation routes

• Settlements + roads prevent wildlife from moving freely

• Not enough protected areas

• not enough land thats free + not protected

  • E.g. All grass is frequently mowed

What to look for in evidence to see if biodiversity loss claims are real

• Reliable: peer-reviewed/published (methodology checked)

• Size: large amounts of data

• Time: long term data of repeated studies to show trends

Citizen Science

What: Use the power of collaborative volunteer research to explore/collect huge data sets - researchers couldnt manage by themselves

Advantages:

• Make huge data sets

• less work for researchers

• easy to do/just log what you find (people feel like making a change)

Disadvantages:

• Biased data

• Untrained citizens = decrease reliability

• Make mistakes

current biodiversity crisis

Biodiversity crisis: unprecedented loss of ecosystems, species and genetic diversity

Cause: Overpopulation

Evidence found by Intergovernmental Science-Policy Platform on Biodiversity + Ecosystem Service

• Evidence

  • Degradation of habitat

  • Species diversity

  • Range of organisms

  • Genetic diversity within a species

2 Methods of biodiversity conservation

1. In Situ - conservation of species in their natural habitats

   • nature/marine reserve + rewinding (leaves land + let land restore) + reclamation

   • Advantages: where theyre supposed to be, behave in natural way, no disruption to behaviour or evolution, cost effective, active management (need to remove invasive species, control predators)

2. Ex situ - conservation of species outside of their natural habitats

   • Zoos, seed banks, botanical gardens, tissue banks

   • Advantages: when in dangerous situations can save = last resort and cant leave them there, preservation of endangered species, preservation of eggs/sperm/seeds

EDGE of existance programme

Evolutionary Distinct + Globally endangered (species)

• You cannot save all of the species - so this program is what decides

• Edge species: above average ED score + critically endangered

• ED Score: isolation on evolutionary tree + how unique they are

• GE score: globally endangered - based on categories

  • Critically endangered

  • Endangered

  • Vulnerable

  • Near threatened

  • Least concern

Estimating number of species

• Between 2 and 10 million species of eukaryotes

• Hard to tell how many once existed

• Can tell through fossil records that cycles of mass extinctions and then increasing biodiversity exist

• Currently in a cycle of increasing biodiversity

Simpson’s Diversity Index

Simpsons Diversity Index

• D: Diversity Index - closer to 1 means High index means high richness + high evenness (not dominated by one/few species) means high diversity

• N: Total number of organisms of all species

• n: number of individuals in a particular species

• sum of number of individuals in a particular species multiplied by same number minus 1

• Divide by Total number of organisms of all species in an area multiplied by same number minus 1

• 1- final answer

  

Worked example: figuring out diversity of place A

Place A:

• Species 1: 10

• Species 2: 7

• Species 3: 9

Place B:

• Species 1: 15

• Species 2: 9

• Species 3: 3

10 (10-1) + 7(7-1) + 9(9-1)

---

26 (26-1)

90 + 42 + 72

---

650

204

---

650

D = 1−0.3138

≈0.686​ —> moderate diversity