12 Enviro Science Revision - U3 Biodiversity

Unit 3 - Biodiversity - Revision

Introduction to Biodiversity

​Biodiversity refers to the variety of life on Earth, including species, genetic, and ecosystem diversity.

Biodiversity is essential for ecosystem resilience, allowing ecosystems to recover from disturbances like natural disasters and human impacts. It also supports ecosystem services such as food production, water purification, and climate regulation.

Introduction to Biodiversity

Levels of Biodiversity:

• Species diversity: Variety of species in an ecosystem.

• Genetic diversity: Variation within species’ genes.

• Ecosystem diversity: Variety of ecosystems in a region.

Genetic Diversity

​Definition

• Variety of genetic traits within a population of a species.

• It allows species to adapt to changes in the environment by providing a pool of traits that might confer survival advantages under new conditions.

Genetic Diversity

​Importance

• Survival of populations experiencing environmental changes such as climate change, habitat destruction, or the introduction of new diseases.

• Populations more likely to contain individuals with traits that allow them to survive, reproduce, and pass on advantageous traits to future generations.

Genetic Diversity

Examples

• Climate Change: A population with diverse genetic traits is more likely to adapt to rising temperatures, altered precipitation patterns, or changing food sources.

• Disease Resistance: Populations with a wide range of immune system genes are more likely to survive disease outbreaks.

Multiple Choice

Why is genetic diversity important for a population facing environmental change?

• It increases the population's size

• It allows the population to adapt to new environmental conditions

• It reduces the need for food and water

• It decreases the population’s ability to reproduce

Open Ended

Explain the difference between species diversity and genetic diversity.

Solution

Species diversity refers to the variety of species within an ecosystem, while genetic diversity refers to the variation of genes within a species. Genetic diversity helps populations adapt to changing environments.

Open Ended

Explain how genetic diversity contributes to a species' ability to survive environmental changes.

​Solution

Genetic diversity allows populations to adapt to environmental changes. If a population has a wide range of genetic traits, individuals with traits that are better suited to new conditions are more likely to survive and reproduce, ensuring the species’ survival.

Ecosystem services

​Provisioning services

Ecosystems provide goods that humans use directly.

• Potable water

• Food

• Fuel

• Fibre

• Pharmaceuticals

Ecosystem services

​Regulating services

Direct processes that control or moderate natural conditions to support human health and environmental stability. These services actively regulate or manage the environment.

• Control of climate

• Control of disease

• Pollination:

• Water purification

Ecosystem services

​Supporting services

Foundational processes that support life on Earth and maintain the conditions necessary for the operation of ecosystems. These services enable or support other services but don’t directly benefit humans in the immediate short term.

• Cycling of nutrients: Recycling elements like nitrogen and carbon to keep ecosystems functioning.

• Soil formation: Creating fertile soil that supports plant life.

• Photosynthesis: Plants converting sunlight into energy, producing oxygen for other organisms.

Ecosystem services

​Cultural services

Non-material benefits that contribute to human well-being:

• Aesthetic values: The beauty of nature, which inspires art and provides enjoyment.

• Recreational benefits: Ecosystems offer opportunities for leisure activities like hiking and fishing.

• Sense of place: The emotional and cultural connection people feel to a particular natural environment.

Multiple Choice

Which of the following is an example of a supporting service provided by ecosystems?

• Pollination

• Photosynthesis

• Food production

• Water purification

Open Ended

Differentiate between provisioning services and regulating services in ecosystems.

​Solution

Provisioning services provide direct goods such as food, water, fuel, and fibre that humans use. Regulating services control environmental processes like climate, disease control, and water purification, which indirectly support human health and well-being.

Biodiversity over time

​Biodiversity through geological time

• Biodiversity has evolved over millions of years.

• Mass extinction events and climate shifts leading to periods of rapid species loss and diversification.

• Major extinction events, such as the one that wiped out the dinosaurs, drastically altered species diversity.

6 Mass Extinctions

• Ordovician-Silurian Extinction (approx. 444 million years ago):
  Caused by a severe ice age that lowered sea levels, wiping out many marine species.

• Late Devonian Extinction (approx. 375-360 million years ago):
  Affected primarily marine life due to climate change, ocean anoxia (lack of oxygen), and possibly asteroid impacts.

6 Mass Extinctions

• Permian-Triassic Extinction (approx. 252 million years ago):
  Known as the "Great Dying," this was the most severe extinction, with up to 96% of marine species and 70% of terrestrial species going extinct, likely caused by volcanic activity, climate change, and ocean acidification.

• Triassic-Jurassic Extinction (approx. 201 million years ago):
  Likely triggered by volcanic activity and climate change, this extinction cleared the way for the dominance of dinosaurs.

6 Mass Extinctions

• Cretaceous-Paleogene Extinction (approx. 66 million years ago):
  Most famous for wiping out the dinosaurs, likely caused by a large asteroid impact and volcanic eruptions, leading to global cooling.

• Current Extinction Crisis (6th mass extinction):
  Many scientists believe we are currently experiencing a sixth mass extinction, driven by human activities such as habitat destruction, climate change, pollution, and overexploitation.

Multiple Choice

Which mass extinction event is known for wiping out the dinosaurs?

• Ordovician-Silurian Extinction

• Permian-Triassic Extinction

• Triassic-Jurassic Extinction

• Cretaceous-Paleogene Extinction

Open Ended

What factors are contributing to what scientists refer to as the "sixth mass extinction"?

​Solution

The "sixth mass extinction" is primarily driven by human activities such as habitat destruction, climate change, pollution, overfishing, and poaching. These factors are causing a rapid decline in biodiversity across the planet.

Fossil Record

• Collection of all known fossils and their placement in the Earth’s rock layers.

• Provides evidence of the existence of species that lived in the past, their evolution, and the environmental conditions they lived in.

Biodiversity over time

Natural changes over varying time scales can have significant impacts on ecosystem diversity, species endemism, the formation of diversity hotspots, and extinction rates.

- Volcanic eruptions, fires, El Nino, tectonic plate movement, evolution

Biodiversity over time

​Endemism

Some species evolve in isolation due to geographical barriers like mountain ranges or oceans, becoming endemic to specific regions. Australia, for instance, has a high number of endemic species, including kangaroos and koalas.

Multiple Choice

Which event is most likely to lead to a loss of species diversity?

• Natural selection

• Geographic isolation

• Climate change

• Re-introduction of species

Open Ended

Explain how tectonic plate movement can lead to the formation of endemic species.

​Solution

When tectonic plates shift, they can isolate populations of species, preventing them from interbreeding with other populations. Over time, these isolated populations evolve separately, leading to the development of species that are only found in specific regions, known as endemic species.

Threats to Biodiversity

​Habitat loss & Over-exploitation

• Human activities such as deforestation, urbanization, and agriculture

• Isolate small populations by destroying habitats.

• Over-exploitation (e.g., overfishing, poaching) reduces population sizes, increasing the risk of extinction.

Threats to Biodiversity

​Inbreeding Due to Small Population Size

• Small, isolated populations

• Leads to reduced genetic diversity and increased susceptibility to diseases and environmental changes.

Threats to Biodiversity

Loss of Pollinators, Dispersal Agents, and Symbionts:

• Species depend on relationships with:

  • pollinators (e.g., bees)

  • dispersal agents (e.g., birds)

  • symbionts (e.g., fungi) for reproduction and survival.

Threats to Biodiversity

• Bioaccumulation: Certain pollutants (e.g., mercury, pesticides) accumulate in the tissues of organisms.

• Biomagnification: These pollutants become more concentrated as they move up the food chain, affecting top predators like eagles and large fish.

Threats to Biodiversity

Climate Change

Rising temperatures, changing weather patterns, and sea level rise alter habitats and force species to migrate, often leading to loss of biodiversity.

Threats to Biodiversity

Disease & Introduced Species

• Both human-induced (e.g., wildlife trade) and naturally occurring diseases can decimate species populations.

• Non-native species introduced by humans often outcompete native species for shelter, food, and water, disrupting ecosystems and causing declines in native biodiversity.

Multiple Choice

Which of the following is an example of habitat fragmentation?

• Species migration

• Seasonal reproduction

• Urban development

• Natural selection

Multiple Choice

Which of the following describes biomagnification?

• The accumulation of pollutants in the tissues of individual organisms

• The increased concentration of pollutants as they move up the food chain

• The loss of species diversity due to habitat destruction

• The introduction of non-native species into an ecosystem

Open Ended

How does overexploitation threaten species survival?

Solution

Overexploitation reduces the population of species to a level where they cannot recover. This can lead to a decline in genetic diversity, disrupting ecosystems and pushing species toward extinction.

Conservation strategies

​Translocation

Moving species from one location to another to reduce threats or restore populations. For example, translocation of Bilbies to predator-free reserves in Australia.

Conservation strategies

Re-introduction

Returning species to areas where they have been locally extinct. This is often done through captive breeding programs. An example is the re-introduction of the Tasmanian Devil to mainland Australia.

Conservation strategies

Captive-breeding programs

Breeding endangered species in captivity to increase population numbers and eventually reintroduce them into the wild. While beneficial, captive breeding can sometimes lead to challenges when animals struggle to adapt to the wild.

Conservation strategies

AND

• Protected areas

• Retaining remnant (left-over) vegetation

• Wildlife corridors/zones

• Gene banks

• Reduction & improved targeting of pesticides in ag/urban areas

Multiple Choice

What is the primary goal of captive breeding programs?

• To domesticate animals

• To increase populations of endangered species

• To reintroduce invasive species

• To improve genetic diversity in wild populations

Multiple Choice

Which strategy involves connecting fragmented habitats to allow species movement and maintain genetic diversity?

• Captive breeding

• Wildlife corridors

• Gene banks

• Protected areas

Multiple Choice

Which of the following strategies is designed to increase population size by reintroducing species into their natural habitats?
A. Gene banks
B. Wildlife corridors
C. Translocation
D. Captive breeding and reintroduction programs

• Gene banks

• Wildlife corridors

• Translocation

• Captive breeding and reintroduction programs

Open Ended

Identify one advantage and one disadvantage of re-introduction programs.

Solution

Advantage: Re-introduction helps restore ecosystems by returning species to their natural habitats.

Disadvantage: Reintroduced species may struggle to survive if their habitat has changed or if they lack survival skills due to captivity.

Open Ended

Describe how translocation of animals helps in conserving species, and give one example of when it might be necessary.

Solution

Translocation involves moving species from a threatened or degraded habitat to a safer, more suitable location. This helps conserve species by giving them a chance to thrive in environments that are better suited to their survival. Translocation may be necessary when a habitat is being destroyed by human activities, such as urbanization or deforestation.

Degraded Ecosystems

Options for renewing/regenerating

• Restoration of habitat

• Erosion control

• Reintroduction of previously endemic species

Multiple Choice

Which of the following methods is commonly used to stabilize soil and prevent erosion in degraded ecosystems?

• Captive breeding

• Planting vegetation

• Wildlife corridors

• Translocation

Multiple Choice

What is the primary goal of reintroducing previously endemic species to an ecosystem?

• To increase genetic diversity within captive populations

• To restore species to areas from which they were previously lost due to natural or human causes

• To prevent natural predators from increasing

• To control invasive species populations

Sampling methods

Grids

• Grids divide an area into equal sections

• Species are sampled in each section.

• This method helps estimate species abundance and distribution across large areas.

Sampling methods

​Transects

• A straight line laid across a habitat.

• Species are sampled at regular intervals along the line

• Study how species composition changes across environmental gradients (e.g., moisture, light).
  

Sampling methods

​Edge Effects

• Occur where different ecosystems meet (e.g., forest meets grassland).

• Species diversity and density may be higher or lower at these boundaries, and transects help assess these changes.
  

Sampling methods

Random vs Systematic

Random sampling is used to eliminate bias, while systematic sampling is used to understand species distribution across a gradient, such as from a riverbank to the forest edge.

Sampling methods

​Quadrats

• Quadrats are square, rectangular, or circular plots used to sample species in a defined area.

• The shape can affect the accuracy of the sample, with square or circular quadrats commonly used to reduce edge effects.

Sampling methods

​Quadrats

• Edge effects in quadrats occur when the species at the boundary of a quadrat are not truly representative of the whole area.

• Larger or multiple quadrats reduce the impact of edge effects.

Multiple Choice

What is the purpose of using a quadrat in ecological studies?

• To estimate species abundance in a defined area

• To measure the height of plants

• To capture animals

• To track migratory patterns

Multiple Choice

What is the purpose of using a transect in biodiversity studies?

• To study genetic diversity

• To measure environmental gradients and species distribution

• To estimate tree height

• To capture animal species for reintroduction

Open Ended

Describe how a transect can be used to study species distribution across different environmental conditions.

Solution

A transect is a line laid across different environmental zones, such as a beach or a forest edge. Samples are taken at set intervals along the transect, allowing researchers to observe how species composition changes along the environmental gradient.

Open Ended

Explain how edge effects might influence the results of a transect study.

​Solution

Edge effects occur at the boundary between two ecosystems, where species composition may be higher or lower than in the core areas. This can lead to an overestimation or underestimation of species diversity in transect studies.

Multiple Choice

Which of the following is a common method to reduce edge effects in quadrat sampling?

• Using larger quadrats

• Using only square quadrats

• Sampling only at the center of quadrats

• Avoiding areas with high species diversity

Assessing Species Diversity

​Mark and Recapture Method

• Used to estimate the population size of mobile species.

• A sample of individuals is captured, marked, and released.

• After a set period, another sample is captured, and the number of marked individuals is recorded.

Assessing Species Diversity

​Calculating population size

Population size is estimated using the formula:
N= (M x C) / R

Where:

• N = estimated population size

• M = number of individuals marked in the first sample

• C = total number of individuals caught in the second sample

• R = number of marked individuals recaptured

Multiple Choice

What is the mark-recapture method commonly used to assess?

• Plant species diversity

• Soil nutrient levels

• Population size of mobile species

• Genetic variation in species

Measurement - Species Diversity

Species Richness

• Refers to the total number of different species present in a given area. It is a simple count of species, regardless of their abundance.

Measurement - Species Diversity

Simpson's index of diversity (SID) (0-1)

• A measure of species diversity that accounts for both species richness and species evenness (the relative abundance of each species). It gives more weight to species that are more abundant.

Multiple Choice

What does species richness measure in an ecosystem?

• The total number of individuals

• The number of species present

• The genetic diversity of species

• The abundance of a single species

Conservation Categories

The International Union for Conservation of Nature (IUCN) Red List categorizes species into the following ranks:

Conservation Categories

• Extinct in the Wild: only survive in captivity or outside their natural habitat but are no longer found in the wild.

• Critically Endangered: extremely high risk of extinction in the immediate future. Population numbers are critically low, and urgent conservation measures are needed.

• Endangered: very high risk of extinction in the near future. Population numbers are rapidly decreasing, and their habitat is severely threatened.

Conservation Categories

• Vulnerable: high risk of extinction in the medium term. They have decreasing populations but are not yet at immediate risk.

• Near Threatened: close to qualifying as vulnerable but are not currently at high risk of extinction.

• Least Concern: widespread and abundant, with no immediate threat to their populations.

Multiple Choice

Which conservation category represents species that are only found in captivity or outside their natural habitats?

• Critically Endangered

• Extinct in the Wild

• Vulnerable

• Near Threatened

Open Ended

Explain the difference between critically endangered and endangered species in terms of their risk of extinction.

Solution

Critically endangered species face an extremely high risk of extinction in the immediate future and require urgent conservation actions. Endangered species are at a very high risk of extinction but may have slightly higher population numbers or more stable habitats compared to critically endangered species.

Qualitative Assessment of Conservation Status

• Availability of suitable habitat

• Geographic distribution

• Population size

Multiple Choice

Which of the following is a key factor in assessing a species' need for conservation action?

A. Genetic diversity within the species
B. Availability of suitable habitat
C. Presence of natural predators
D. Species’ colouration

• Genetic diversity within the species

• Availability of suitable habitat

• Presence of natural predators

• Species’ colouration

Open Ended

Explain how changes in geographic distribution can increase the risk of extinction for a species.

​Solution

Species with a restricted or shrinking geographic distribution are more vulnerable to habitat loss and environmental changes. If the species is confined to a small area, a natural disaster or human activity can lead to the complete loss of their habitat, increasing their risk of extinction.

Legislation for Conservation

A range of legal treaties, agreements, and regulatory frameworks are in place to protect threatened species at various levels:

Legislation for Conservation

International

• Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES):
  An international agreement that regulates trade in endangered species to prevent over-exploitation.

• IUCN Red List of Threatened Species:
  A global inventory assessing the conservation status of species to inform global conservation priorities.

Legislation for Conservation

National

• Environment Protection and Biodiversity Conservation Act 1999 (Cth):

  (EPBC Act)
  The primary national environmental law in Australia, protecting biodiversity and managing impacts on nationally significant species and ecosystems.

Legislation for Conservation

State

• Flora and Fauna Guarantee Act 1988 (Vic):

  
  A key state law aimed at protecting endangered species and ensuring the conservation of Victoria’s biodiversity.

Legislation for Conservation

Local

• Classified World Heritage Areas:
  Areas protected due to their cultural, historical, and environmental significance, such as the Great Barrier Reef.

• Local Government Conservation Covenants:
  Legal agreements that protect habitats on private land, ensuring long-term conservation efforts at the local level.

Multiple Choice

What is the purpose of the EPBC Act?

• To regulate air pollution

• To protect endangered species and their habitats

• To manage fishing quotas

• To monitor water quality

Open Ended

Explain how CITES helps in the conservation of endangered species.

​Solution

CITES regulates the international trade of endangered species by ensuring that listed species are not exploited commercially. It prevents over-exploitation and helps species recover by limiting exports and imports.

Additional Practice

Multiple Choice

What is a key threat to biodiversity caused by human activity?

• Natural selection

• Habitat fragmentation

• Seasonal migration

• Natural predation

Open Ended

Explain the difference between genetic diversity and species diversity.

Open Ended

How does habitat fragmentation affect biodiversity?

Open Ended

Describe how a transect can be used to assess biodiversity in different habitats.

Multiple Choice

What is the main goal of translocation in conservation?

• To domesticate species

• To restore species to new habitats

• To move species to safer habitats

• To increase genetic diversity

Open Ended

Explain one advantage and one challenge of re-introduction programs.

Multiple Choice

What is the primary purpose of a wildlife corridor?

• To improve genetic diversity

• To control pests

• To allow species to migrate between habitats

• To reduce habitat size

Open Ended

How does the EPBC Act contribute to the conservation of biodiversity in Australia?

Multiple Choice

Which of the following is a threat to biodiversity caused by human activity?

• Overexploitation

• Natural migration

• Seasonal breeding

• Genetic drift

Multiple Choice

Which of the following is an international treaty aimed at regulating trade in endangered species to prevent their extinction?

• IUCN Red List

• CITES

• Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)

• Flora and Fauna Guarantee Act 1988 (FFG Act)