Biological Diversity
Module 3 - Biological Diversity
Content Focus
Biodiversity is crucial for maintaining balance within Earth’s ecosystems.
Biodiversity can be influenced both slowly and rapidly due to natural selective pressures.
Human activities also significantly impact biodiversity within short time frames.
Key Learning Areas
Understanding the Theory of Evolution by Natural Selection and the implications of various selective pressures.
The importance of monitoring biodiversity to anticipate future ecological changes.
The role of monitoring abiotic environmental factors in enabling ecologists to formulate strategies to mitigate negative biological changes.
Examination of organism adaptations that enhance survival in specific environments.
M3-1: Inquiry Question
How do environmental pressures promote changes in species diversity and abundance?
a) Predict the effects of selection pressures on organisms in ecosystems, including:
Biotic Factors (living components of the ecosystem)
Abiotic Factors (non-living elements of the ecosystem)
b) Investigate population changes influenced by selection pressures over time, focusing on:
Cane toads in Australia
Prickly pear distribution in Australia.
Review - Ecosystems
An ecosystem is defined as:
Ecosystem: The interaction of all living (biotic) organisms in a specific area with their physical (abiotic) environment.
Ecosystems can vary in size, exemplified by environments such as rainforests and fish tanks.
They must be self-sustaining, existing long-term with minimal external inputs.
Two major categories: Terrestrial (land) and Aquatic (water).
Terrestrial Ecosystems
Grouped into biomes based primarily on climatic conditions. Examples of biomes include:
Forests: Tropical, boreal, and temperate (coniferous and deciduous)
Tundras: Arctic and alpine types
Grasslands
Deserts
Aquatic Ecosystems
Aquatic ecosystems dominate Earth, with oceans covering 75% of the Earth’s surface. They divide into:
Freshwater Ecosystems: Generally contain less than 1% salt and comprise lakes, ponds, swamps, rivers, streams, and springs, covering 1.8% of Earth's surface.
Marine Ecosystems: High salt concentrations, including open oceans, deep-sea ecosystems, coral reefs, estuaries, mangrove forests, and salt marshes. Estuaries are extremely productive habitats supporting diverse life.
Review - Organism Interactions
Energy flow in ecosystems is tracked via food chains and food webs.
Food Chain: Illustrates a singular pathway of energy transfer; implies a linear sequence (e.g., Plant → Herbivore → Carnivore).
Food Web: A complex network showcasing all potential feeding relationships within a community.
Energy is transferred through trophic levels, with only about 10% of energy passing from one level to the next.
Question: What are the starting points of food chains and webs? Include reasons.
Energy Flow in an Ecosystem
Typical energy transfer illustration:
Producers like plants capture solar energy, which is reduced at each level of consumption (e.g., heat loss).
Example Diagram:
Producers: 200 units of energy → Herbivores: 20 units (10% efficiency); Carnivores: 2 units.
Energy Transfer and Biomass Pyramids
Trophic levels define ecological positioning in food chains and webs.
Not all energy is transferred; a significant proportion transforms into non-useable forms (heat).
A large biomass of producers supports a smaller number of higher-level consumers due to energy inefficiency.
Importance of Sunlight for Ecosystem Energy
Energy flows begin with sunlight, fundamental for photosynthesis.
Question: What if sunlight was unavailable?
Selection Pressures
Definition: Factors that impact an organism’s survival, reproduction, and behavior, influencing evolution.
Positive Selection Pressures: Factors enhancing reproductive success (e.g., increase of ants is beneficial for echidnas).
Negative Selection Pressures: Factors decreasing survival chances (e.g., rising water temperatures threaten coral ecosystems).
Impact of Abiotic Factors on Selection Pressures
Components: Atmosphere (air), lithosphere (land), hydrosphere (water) contribute to unique selection pressures, affecting organism distribution.
Non-living factors influence survival through resource availability and climatic conditions.
Earth's Spheres and Their Interactions
The four spheres include:
Lithosphere (land)
Atmosphere (air)
Biosphere (living things)
Hydrosphere (water)
All spheres interact, and alterations in one can impact others (e.g., human-induced changes).
Recommended Research Task
Evaluate one abiotic factor; explore its impact on a specific organism’s evolutionary trait in both aquatic and terrestrial habitats.
Impact of Physical Changes
Environmental factors like light levels, temperature, rainfall, and topography induce changes in organisms.
Light Impact
Affects plant and animal behaviors, influencing growth, reproduction, colorations, and migration patterns.
Organisms like Leadbeater’s possum adjust behaviors through circadian rhythms due to light availability.
Temperature Adaptations
Organisms exhibit various temperature adaptations, such as dormancy states during unfavorable conditions.
Example adaptations include:
Black bears: hibernation during winter, reducing metabolic rates.
Australian Banksia: specific heat requirements for seed germination.
Rainfall Effects on Evolution
Altered rainfall patterns lead to evolutionary adaptations in various species for water conservation.
Examples:
Eucalyptus trees and water-holding frogs adapted to arid environments.
Topographical Effects
Different land shapes affect moisture distribution and soil characteristics, creating diverse microenvironments.
Chemical Changes and Their Impact
Changes in pH and salinity influence plant adaptations and nutrient cycles within ecosystems (e.g., hydrangea color change due to soil pH).
Examples of Chemical Adaptations
Mangroves display specific adaptive strategies for salinity tolerance; resistance in sheep blowfly to chemical pesticides demonstrates evolution in response to anthropogenic pressures.
Human Impact on Biological Diversity
Human activities often disrupt ecosystems by introducing new selection pressures, leading to shifts in biodiversity.
Keystone Species Importance
Keystone species play pivotal roles in ecosystem structure; their removal can result in significant ecological imbalance.
Example: Sea otters are pivotal in maintaining kelp forest health.
Human Impact Example
Human-driven changes (like culling predators) lead to cascading ecological consequences in habitats, affecting various species' survival.
Review Questions and Future Tasks
Define key terms like selection pressure, biotic factors, etc.
Elaborate on the relationship between temperature, survival, and adaptation.
Assess the implications of human impacts on ecosystem dynamics.