Biodiversity and Sustainability Notes

Biodiversity and Sustainability

What is Biodiversity?

• Biodiversity, or biological diversity, refers to the variety of life at all levels of organization.

• It includes all living organisms from terrestrial, marine, and other aquatic ecosystems, as well as the ecological complexes they belong to.

• The ecological complex includes diversity within species, between species, and of ecosystems.

Types of Biodiversity

• There are three main types of biodiversity:

  • Genetic diversity: The variety in DNA within a species. An example is the color and spots of ladybugs.

  • Species diversity: The number of different species present in a specific region or community. An example is a woodland forest with 4-5 different species of trees.

  • Ecosystem diversity: The variety of different ecosystems within an area. Examples include grasslands, tundra, and forests. A coral reef is an example of ecosystem diversity, composed of coral, sea stars, worms, snails, kelp, sea grass, etc.

True/False Questions on Biodiversity

• Species diversity refers only to the number of different species in an ecosystem, not their relative abundance (False)

• Species diversity is the number of species of animals and plants present in a specific region or community (True)

• Coral Reef is an example of Species diversity (False: Ecosystem diversity)

• Cloning organisms, such as plants, decreases genetic diversity within a population (True)

• High genetic diversity is generally associated with a lower risk of extinction for a species (True)

• Color and spots of butterfly is an example of species diversity (False: Genetic Diversity)

• Dubai Desert is home to cacti dune grass. This is an example of ecosystem diversity (False: Genetic Diversity)

• Wetland, grassland, forest is an example of ecosystem diversity (True)

Natural Selection and Diversity

• Natural selection is the process by which populations of living organisms adapt and change their traits for survival.

• Natural selection can either increase or decrease diversity in populations by selecting for or against specific genes or gene combinations.

  • Increase in Diversity: Adaptive Radiation (e.g., finches bird species)

  • Decrease in Diversity: Directional Selection (e.g., origin of giraffes’ long necks) and Stabilizing Selection (favors intermediate traits)

Mutation and Diversity

• A mutation is a change in DNA, which creates a new allele and increases genetic diversity.

• The appearance of new mutations is the most common way to introduce novel genotypic and phenotypic variance.

• Example: A mutation in a garden rose causing it to produce flowers of different colors introduces a new allele into the population, increasing diversity and potentially being passed to the next generation.

Gene Flow and Diversity

• Gene flow is the movement of alleles (genes) in and out of a population due to the migration of individuals or gametes.

• Gene flow makes populations more genetically similar because it involves the transfer of genetic material, thus decreasing diversity.

• Gene flow acts against speciation, preventing the formation of new species.

What is Biodiversity Loss?

• Biodiversity loss describes the decline in:

  • Number of species

  • Genetic variability of species

  • Biological communities in a given area

Types of Biodiversity Loss

• Extirpation: The disappearance of a particular population from a given area, but not the entire species globally (e.g., Grizzly Bear no longer found in Manitoba but still exists in Alberta, Canada).

• Extinction: The permanent disappearance of a species from the Earth (e.g., Dodo bird, Mammoth, Dinosaur).

• Mass extinction: The extinction of a large number of species within a relatively short period of geological time.

  • Example: 95% of marine species died during the Permian Mass Extinction.

Extinct vs. Endangered Species

• Extinct animals are animal species that have stopped breeding, died, and no longer exist.

• Endangered species are organisms whose numbers have reduced drastically and, if not conserved, will become extinct (e.g., Arabian oryx, and Dudong).

What is Mass Extinction?

• Mass extinction is a widespread event that wipes out the majority (over 50%) of living plants and animals.

• This extinction occurs due to factors such as a catastrophic global event or widespread environmental change that happens too rapidly for most species to adapt.

• There have been five major mass extinctions in Earth's history, known as the "Big Five."

• The most predominant was the Permian extinction, which occurred 250 million years ago.

The Five Mass Extinctions

• The most predominant mass extinction was the Permian extinction (happened 250 million years ago).

• About 95% of marine species and 70% of land species died.

The 6th Mass Extinction

• The Earth appears to be undergoing a 6th mass extinction.

• Historically, mass extinctions have been caused by natural events like volcanic eruptions and asteroid collisions.

• The 6th mass extinction is primarily due to human activities, including deforestation, mining, and carbon dioxide emissions.

• Recent victims include the passenger pigeon, Tasmanian tiger, Baiji, or Yangtze river dolphin.

• According to the International Union for Conservation of Nature, more than 27% of all species are threatened with extinction:

  • 40% of amphibians

  • 25% of mammals

  • 33% of coral reefs

Drivers of Biodiversity Loss

• Indirect drivers:

  • Demographic

  • Economic

  • Socio-political

  • Cultural & religious

  • Science & Technology

• Direct drivers:

  • Habitat change

  • Climate Change

  • Invasive species

  • Overexploitation

  • Nutrients & pollution

Major Threats to Biodiversity

• Habitat Loss: Deforestation, agricultural, and industrial activity.

• Climate Change: Fossil fuel and greenhouse gas emissions.

• Invasive species: Introduction of exotic species and genetically modified organisms.

• Overexploitation: Overuse of resources through activities like hunting, fishing, and farming.

• Nutrient Pollution: Excessive use of fertilizers (excess Nitrogen and Phosphorus) and pesticides.

Biodiversity & Ecosystem

What is an Ecosystem?

• An ecosystem is a community of living organisms in a given area, interacting with each other and with their non-living environments.

  • Biotic Factors: Living components, such as plants, animals, and other organisms.

  • Abiotic Factors: Non-living components, such as weather, air, sun, and soil.

• Biosphere: Earth’s largest ecosystem, consisting of five main types of biomes.

  • Biomes: Aquatic, Grassland, Forest, Desert, and Tundra (treeless regions found in the Arctic and on the tops of mountains).

Ecosystem: Level of Organization

• Ecology is the branch of biology that studies the relationship between organisms and their environments.

• Ecologists study interactions among organisms at different levels:

  • Ecosystems: Studies interactions among groups of organisms and their interactions with abiotic factors in their environment.

  • Communities: Studies interactions between different organisms in a specific area.

  • Populations: Studies groups of organisms of the same species and how they change over time.

  • Individual organisms: Studies individual organisms and how they interact with their environment.

Ecosystem Energy Flow

Food Chains and Food Webs

• Energy flow through the ecosystem is represented by food chains and food webs.

• Food Chain: A basic network that shows the linear flow of energy from one trophic level to another.

• Food Web: A multitude of interconnected food chains at many trophic levels.

• Each organism is part of one or more food chains.

Food Chains and Trophic Levels

• The organisms in food chains are separated into functional units called trophic levels based on how they obtain energy.

• Trophic Level: The position that an organism occupies in a food chain or a group of organisms in a community that occupy the same position in food chains.

Food Chain vs. Food Web

Food Chain

• Single linear pathway.

• Isolated food chains decrease the stability of the ecological community.

• One individual occupies one trophic level only.

• 10% of energy passes from one trophic level to another.

Food Web

• Made of several interconnecting pathways.

• More complex food webs increase the stability of the ecological community.

• One individual occupies many trophic levels.

Components of Food Chain and Trophic Levels

• Producers: Organisms that turn simple inorganic compounds into complex organic ones through photosynthesis. Examples include trees, flowers, grasses, ferns, mosses, algae, and cyanobacteria.

• Consumers: Organisms that rely on other organisms as food, animals that eat plants or other animals.

  • Herbivore: Eats plants directly (e.g., Deer, goose, cricket, vegetarian human, many snails).

  • Carnivore: Eats meat (e.g., Wolf, pike, dragonfly).

  • Omnivore: Eats plants and meat (e.g., Rat, humans).

  • Scavenger: Eats food left by others (e.g., Coyote, skunk, vulture, crayfish).

  • Parasite: Lives in or on another organism, using it for food (e.g., Tick, tapeworm, many insects).

• Decomposer: Returns organic compounds to inorganic compounds, is an important component in recycling (e.g., Bacteria, fungi).

Ecological Pyramids

• Ecological pyramids are graphical representations of the relationship between different living organisms at different trophic levels.

• Pyramid of Energy: Shows only 10% energy transfer from one trophic level to the next.

  • Approximately 90% of the energy in a trophic level is lost as heat (metabolic heat) because that energy is used for processes such as movement, growth, respiration, and reproduction.

• All organisms, directly or indirectly, get their energy from the Sun.

• Energy flows from the bottom to the top layer of the pyramid.

Ecological Pyramids: Three Major Types

• Pyramid of Numbers: Compares the number of individual organisms at different trophic levels of food chain.

• Pyramid of Biomass: Compares the biomass of the members of the food chain.

• Pyramid of Energy: Represents the amount of energy at each trophic level of a food chain.

• In all the ecological pyramids, producers (organisms that produce their own food) are found at the lowest trophic level and contains the highest amount of energy.

Pyramid of Numbers

• Description: Shows the number of individual organisms at each trophic level in an ecosystem.

• Shape: Can be upright, inverted, or even irregular, depending on the ecosystem.

• Example: In a forest ecosystem, there may be fewer large trees (producers) compared to many herbivores (primary consumers) like insects or small mammals.

Pyramid of Biomass

• Description: Shows the total mass of living organisms (biomass) at each trophic level, typically measured in grams (g) or pounds (lb) per square meter (g/m^2 or lb/m^2)

• Shape: Usually upright (except in few ecosystems), because the biomass generally decreases at each successive trophic level.

• Example: The biomass (weight) of producers (plants) is greater than that of herbivores or carnivores in most ecosystems, making the pyramid appear broad at the bottom and narrower as you go up.

Pyramid of Energy

• Description: Shows the flow of energy through each trophic level, usually measured in kilocalories (Kcal) or kilojoules (KJ). It illustrates how energy is transferred from one level to the next.

• Shape: Always upright, because energy decreases as it moves up the trophic levels. Only about 10% of the energy is transferred from one trophic level to the next; the rest is lost as heat or used in metabolic processes.

• Example: The energy available to primary consumers is much greater than the energy available to secondary consumers.

Ecological Succession

• Ecological succession is a natural change in the environment and the process by which a biological community changes over time.

• These changes may be slow and hard to see over short time periods.

• Examples include the growth of hardwood forests and the development of the Great Barrier Reef.

• There are two types of succession:

  • Primary succession

  • Secondary succession

Primary vs. Secondary Succession

• Primary Succession: Occurs in areas where no life existed previously.

  • Begins with pioneer organisms that can tolerate extreme conditions (hot and cold; dry and wet).

  • Occurs on tops of mountains, newly formed volcanic rock, or rock newly exposed by erosion or glaciers.

• Secondary Succession: Occurs in areas where a community previously existed but has been removed or changed by a natural or human-induced disaster.

  • Occurs after a forest fire, in abandoned agricultural land, or after forest harvesting.

  • Soil is already present, so secondary succession occurs much faster.

Pioneer Organisms (Disaster Taxon)

• A pioneer organism, also called a disaster taxon, is an organism that populates a region after a natural disaster or mass extinction that kills most of the life.

• Pioneer organisms are able to survive in harsh environments and can grow without soil in rocks or sand, being the first to grow in a barren area.

• They physically break up the rocks, extract minerals, and decompose to produce soil.

• Examples include moss, dune grass, and lichens (a combination of algae and fungus).

Climax Community

• A climax community is a stable, mature ecological community that has reached the final stage of ecological succession.

• It is characterized by a balance between the biotic (living organisms) and abiotic (environmental) factors of an ecosystem.

  • It tends to remain relatively unchanged over time unless disrupted by major environmental events like fire, flooding, or human intervention.

• Example: Desert (drought-tolerant plants, cacti, and animals adapted to dry conditions) and Tundra(mosses, lichens, and small shrubs adapted to extreme cold and short growing seasons).

Chemical/Nutrient Cycling: Biogeochemical Cycles

• Life on earth depends on recycling essential chemical elements.

• Nutrients move between organic and inorganic parts of the ecosystem in cycles.

• Cycles may be global or local, known as biogeochemical cycles.

• A biogeochemical cycle is one of several natural cycles in which conserved matter moves through the biotic and abiotic parts of an ecosystem.

Types of Biogeochemical Cycles

• The Hydrological Cycle (Water Cycle): Water moves from the land and ocean surface to the atmosphere and back as precipitation.

• The Carbon Cycle: Carbon moves from the atmosphere to plants, and from plants to animals.

• The Phosphorus Cycle: Phosphorus moves through rocks, water, soil, and organisms.

Water Cycle (Hydrologic Cycle)

• The water cycle is a biogeochemical cycle that involves the continuous movement of water on, above, and below the surface of the Earth. The mass of water on Earth remains fairly constant over time.

• Participants:

  • Oceans: Largest source of water vapor through evaporation, play a critical role in maintaining the water and back on earth via precipitation.

  • Plants: Participate through transpiration, releasing water vapor into the air.

  • Rivers and Lakes: Serve as reservoirs for water and transport water from land to ocean.

Water Cycle Processes

• Plants absorb water from the soil and release it into the atmosphere via transpiration.

• Water in oceans, lakes, and rivers evaporates into the atmosphere via evaporation and back to earth via precipitation.

• When the temperature drops, water vapor cools and becomes tiny water droplets, forming clouds (condensation).

• Water falls from the atmosphere to the Earth's surface (rain, snow) through precipitation.

Carbon Cycle (Gaseous Cycle)

• The carbon cycle is the process by which carbon atoms are recycled through the Earth's atmosphere, oceans, soil, and living organisms.

• Participants:

  • Plants (through photosynthesis): Plants use CO2 and release O2 during photosynthesis.

  • Animals (through respiration): Animals eat organic molecules and release CO_2.

  • Microorganisms (through decomposition): Break down organic matter, releasing carbon into the soil or atmosphere.

  • Oceans: Absorption of CO_2, marine life photosynthesis.

  • Fossil Fuels: Carbon stored over geological timescales.

  • Soil: Carbon storage and release.

Sedimentary Cycle (Phosphorus Cycle)

• The phosphorus cycle is slower than the carbon and nitrogen cycles, having no significant gaseous phase.

• It mainly moves through soil, water, and living organisms and is a vital nutrient for all life.

• Participants:

  • Rocks and Minerals (Lithosphere): Phosphate minerals in rocks release phosphorus into the soil and water.

  • Soil (Terrestrial Ecosystems): Soil stores phosphorus and allows plants to absorb it.

  • Plants (Biosphere): Plants take up phosphorus from the soil and pass it along the food chain.

  • Animals (Biosphere): Animals consume plants (or other animals), storing phosphorus in their tissues and releasing it when they die or excrete.

  • Decomposers (Biosphere): Microorganisms break down organic matter, releasing phosphorus back into the soil.

The Nitrogen Cycle

• Summary

  • Nitrogen-fixing bacteria: Present in the soil and within the root nodules of some plants, convert nitrogen gas present in the atmosphere to ammonia.

  • Nitrifying bacteria: Convert ammonia to nitrites or nitrates, and these compounds are absorbed by plants.

  • Denitrifying bacteria: Release nitrogen gas back to the atmosphere.

  • Decomposer: Convert dead plants and animals, and waste products such as breaking ammonia and urea into usable form and recycle these usable nitrogen compounds.