Ecology Explorations Term 1 & 2 Summary

Phenotypes and Genetic Diversity

• Genetic Diversity: Hundreds of different organisms differ through genetic diversity within species.
• Gene Pool:
  • Definition: The collection of genes within an interbreeding population at a particular time.
  • Includes all alleles of genes in a population (of a single species).
  • Each organism is unique due to its genes, leading to different phenotypes (hair color, skin color, height, etc.).
• Population Size and Survival: Larger populations have a higher chance of containing members with the genes necessary to survive.
• Shallow Gene Pool: Breeding between closely related individuals can lead to more pronounced flaws or disabilities in offspring, increasing the chance of defective offspring. However, healthy offspring are still possible.
  • Example: Camel man Jack, who had children with his daughters, granddaughters, and great-granddaughters, and all offspring were healthy.
• Preserving Genetic Diversity: Increases the opportunity to discover new resources (e.g., painkillers and medications from the Amazon Rainforest).
• Learning Intention: Understand how variation arises within a species and its contribution to survival and evolution.
• Example Species: Domestic Cats.

Biodiversity and Species Classification

• Learning Intention: Understand what a species is and why we classify them.
  *Families and Subfamilies:
  *Family: Felidae – Includes big cats like tigers, lions, jaguars, and leopards.
  *Subfamily: Felinae – Includes cats like the cheetah, which cannot retract its claws.
• Hybrid Species:
  • Liger: Hybrid of a male lion and a female tiger; can grow larger than either parent (over 550kg).
  • Tigon: Hybrid of a male tiger and a female lion.
  • Mules: Offspring of a female horse and a male donkey; cannot breed with horses or donkeys.
  • Hinny: Offspring of a male horse and a female donkey; strong but smaller than a horse.
  • Jaglion: Result of a lion breeding with a black jaguar; infertile and one-of-a-kind.
  • Grolar Bear: Grizzly bear crossed with a polar bear; a wild hybrid.
  • Zonkey: Zebra crossed with a donkey; product of science and selective breeding; retains traits from both parents but cannot produce offspring.
  • Humpless Camel: Camel bred with a llama via artificial insemination for llama wool.
  • Beefalo: Male cow and female buffalo crossbred to produce more beef and milk; less fat and cholesterol than cow beef; can create offspring.
  • Dzo: Yak and cow hybrid, created out of necessity; very large; females are fertile, but males are infertile.
  • Spider Goats: Genetically engineered to produce milk containing spider silk using golden web spider DNA for scientific purposes.
  • Wholphin: Female bottlenose dolphin with a male killer whale hybrid.
• Historical Classification:
  • Aristotle (350 BC) classified plants and animals based on:
    • Plants: Trees, shrubs, herbs (based on height).
    • Animals: Land mammals, flying animals, sea animals (based on habitats).
• Linnaeus’s Binomial System:
  • Proposed a binomial system of naming species using Latin.
  • Example: Australian Magpie - Gymnorhina tibicen.
    • First part (Gymnorhina) is the genus.
    • Second part (tibicen) is the species.

Classification Examples

• Examples of Animals That Look Like Big Cats:
  • Panthera leo - Lion
  • Panthera tigris - Tiger
  • Panthera onca - Jaguar
  • Panthera pardus - Leopard
• Examples of Plants That Look Like Gum Trees:
  • Eucalyptus saligna - Sydney Blue Gum
  • Eucalyptus viminalis - Manna Gum
  • Eucalyptus camaldulensis - River Red Gum
• Breeds, Races, and Varieties:
  • Different breeds of domestic dogs can produce offspring, indicating they are the same species.
  • Kelpie bred with a Blue Heeler produces the Australian Cattle Dog.
  • Crossbreeding creates many flower varieties within the same species (e.g., roses).
  • Domestic horses and cows have different breeds.
  • Humans are classified into different races within the species Homo sapiens.
• Genus: Linnaeus grouped similar species into genera.
  • Members of a genus share similar features.
    • Felis (small cats) have retractile claws and walking pads.
    • Panthera (large cats) share similar features but are larger.
    • Acinonyx (cheetahs) cannot retract their claws and are in a different genus.
    • All these genera belong to the family Felidae.

Alleles, Gene Pools, and Genetic Variation

• Alleles: Alternative forms of a gene at the same place on a chromosome.
• Genetic Variation: Can be described by the frequency and number of different alleles within a population.
• Genotype: Combination of alleles for a particular trait within an individual.
• Gene Pool: The total genetic information of a population, usually expressed as allele frequencies.
• Gene Flow: Movement of individuals and their alleles between populations.
• Genetic Drift: Changes in allele frequency due to chance events (e.g., floods, fires).
• Natural Selection: Process by which organisms better adapted to their environment pass on their genes to the next generation.

Genetic Drift vs. Natural Selection

• Genetic Drift:
  • Random process affecting allele frequency, especially in small populations.
  • Occurs due to chance events.
  • Can lead to loss or fixation of alleles, regardless of their impact on survival or reproduction.
• Natural Selection:
  • Non-random process driven by environmental pressures.
  • Traits that offer a survival or reproductive advantage become more common.
  • Favors traits that enhance fitness and adapts populations to their environment.
• Key Difference: Genetic drift is random, while natural selection favors advantageous traits.

Divergence, Convergence, and Adaptation

• Speciation: The process resulting in the formation of a new species.
• Adaptation: Characteristic or behavior that allows a species to survive and reproduce more effectively.
• Gene Flow: The flow of genes from one generation to the next.
• Isolation: Division of a population into two groups.
• Diverge: Species become more different over time due to different selection pressures.
• Homologous Structures: Structures similar in different species because they evolved from a common ancestor, but do not necessarily have the same function.
• Adaptation: Variation within a species favored by environmental conditions.
• Variations within a species provide "options" for survival when environmental conditions change.
• Permanent Barrier Leads to Speciation: When a permanent barrier separates a species, different mutations and selection pressures allow for the formation of a new species.
• Pentadactyl Limb: Example of a homologous structure in tetrapods.

Nitrate Contamination

• Excessive nitrate (oxygen and nitrogen) in water sources, typically due to agricultural runoff, industrial waste, and other waste disposals.
• Health Concerns:
  • Methemoglobinemia (Blue Baby Syndrome): Nitrates react with hemoglobin, turning it into methemoglobin, which reduces blood's ability to carry oxygen.
• Ecological Concerns:
  • Excess nitrate causes rapid algae growth, leading to harmful algae blooms.
  • Algae death removes oxygen, creating "dead zones" where aquatic life cannot survive.
  • Disrupts ecosystems and food chains.
• Solutions:
  • Distillation (boiling) leaves nitrates behind, making water safe.
  • Reverse osmosis and ion exchange can reduce nitrate.
• Preventative Measures:
  • Improved agricultural practices, reducing fertilizer use, and using blockers to prevent runoff.
  • Regular water testing.
• Research: Scientists are researching ways to reduce water contamination and stricter regulations on water areas to prevent accidental contamination.

Energy Transfer in Food Chains

• Energy transfer through trophic levels:
  Producers (1000kj) \longrightarrow PrimaryConsumers (100kj) \longrightarrow SecondaryConsumers (10kj) \longrightarrow TertiaryConsumers (1kj)
• Energy Loss: 90% of energy is lost at each step.

DDT Contamination Example

• DDT (pesticide) sprayed on plants washes into waterways.
• Contamination pathway: Plants → humans; DDT infested water → ocean → planktons → small fish → larger fish → largest fish → humans

States of Matter and the Water Cycle

• States of Matter:
  • Solid to liquid: melting
  • Liquid to gas: boiling or evaporation
  • Gas to liquid: condensation
  • Liquid to solid: freezing
• Water Cycle: Evaporation → Condensation → Precipitation (rain, hail, sleet, snow)

Nutrient Cycles: The Nitrogen Cycle

• The interaction of Earth’s spheres can be demonstrated using nutrient cycles, specifically the nitrogen cycle.
• Nitrogen (N) is a key nutrient for plant and animal growth.
• Nitrogen Cycle:
  1. Nitrogen moves from the atmosphere to the biosphere via nitrogen-fixing bacteria.
  2. Bacteria turn nitrogen into a form plants can absorb for growth (biosphere).
  3. When plants and animals die, nitrogen decomposes into the soil (lithosphere/biosphere).
  4. Nitrogen moves from the soil back to the atmosphere via denitrifying bacteria.
• N_2 in the air (75%)
• Nitrogen Fixation (by bacteria)

Glossary of Ecosystem Terms

• Producer
• Primary Consumer
• Secondary Consumer
• Tertiary Consumer
• Food Chain
• Food Web
• Collaboration
• Mating
• Competition
• Scavengers
• Predator Prey
• Symbiosis
• Mutualism
• Parasitism
• Commensilism
• Amenialism

Ecosystems - Key Terms and Interrelationships

• Original Source of Energy: The sun.
• Eight Key Terms for Interrelationships Between Organisms:
  • Predation: One organism (predator) hunts and consumes another (prey).
  • Mutualism: Both organisms benefit.
  • Commensalism: One species benefits while the other is neither helped nor harmed.
  • Parasitism: One organism (parasite) benefits at the expense of the host.
  • Competition: Two organisms vie for the same resource.
  • Symbiosis: A close and long-term biological interaction between two different biological organisms.
  • Herbivory: Animals feed on plants.
  • Detritivory: Organisms feed on dead organic matter, recycling nutrients.

Trophic Levels and Energy Flow

• Trophic Levels in a Food Chain
  • Example Food Chain: Grass → Grasshopper → Frog → Snake → Hawk
    | Organism | Trophic Level |
    | :----------- | :---------------------------------- |
    | Grass | Producer (1st level) |
    | Grasshopper | Primary Consumer (2nd level) – herbivore |
    | Frog | Secondary Consumer (3rd level) – carnivore |
    | Snake | Tertiary Consumer (4th level) – carnivore |
    | Hawk | Quaternary Consumer (5th level) – top predator |
    Each step up is a transfer of energy with decreasing efficiency.
• Energy Flow Through Food Chains
  • Energy starts with the sun, which producers convert into chemical energy through photosynthesis.
  • Consumers then obtain energy by eating other organisms.
  • Only about 10% of energy is transferred from one trophic level to the next.
  • The rest is lost as heat, or used for life processes like movement and reproduction.
  • Food chains rarely go beyond 4–5 levels—there just isn’t enough energy.
    In ecosystems, this food chains are often better visualized as a food web.
• Animals And Trophic Levels
  • Some animals are herbivores (eat both plants and animals) which means they can occupy multiple trophic levels in a food web.
  • For example a bear that eats berries (producer level) is a primary consumer, but when it eats fish (secondary consumers or tertiary consumers) it acts as a tertiary consumer.

Symbiotic Relationships and Keystone Species

• Symbiosis Relationships
  • Predation: Zebra and lion
  • Competition: Trees competing for sunlight.
  • Mutualism: Bees and flowers.
  • Commensalism: Birds nesting in a tree.
  • Parasitism: Fleas on a dog.
• Keystone Species
  • A keystone species has a disproportionately large effect on its ecosystem relative to its abundance.
  • Removing it can cause dramatic changes, often leading to ecosystem collapse.
  • Example: Sea Otters and Kelp Forests
    • Sea otters prey on sea urchins, which feed on kelp.
    • If otters are removed:
      • Sea urchin populations explode, overgrazing the kelp forests.
      • Kelp forests disappear, removing habitat for many marine organisms.
      • The entire ecosystem structure shifts, and biodiversity plummets.
• Keystone Species vs. Ecological Engineers

  Feature	Keystone Species	Ecological Engineer
  Role	Regulates ecosystem dynamics	Physically alters the environment
  Effect	Trophic (feeding relationships)	Structural (habitat-forming or modifying)
  Example	Wolves in Yellowstone	Beavers build dams
  Impact of Removal	Leads to trophic cascades	Causes habitat loss or major changes to ecosystem function

  • A keystone species holds the ecosystem together by keeping populations in check.
  • An ecological engineer reshapes the ecosystem by building or modifying habitats.

Ecological Examples and Relationships

• Ecological Engineers: Some organisms can even be both keystone species and ecological engineers (e.g., beavers).
• Yellowstone Wolves:
  • Reintroduction of wolves reduced elk overpopulation and changed their behavior.
  • Vegetation rebounded, supporting beavers, amphibians, fish, and birds.
  • Rivers changed course due to stabilized banks and improved vegetation—a trophic cascade.
• Predator-Prey Relationships:
  • An interaction where one organism (the predator) hunts, kills, and eats another (the prey).
  • Regulates population sizes and drives natural selection.
  • Example: Lynx (predator) and snowshoe hare (prey) exhibit cyclical population patterns.

Population Dynamics and Growth Strategies

• Impact of Overpopulation:

• Resource Depletion
• Habitat Degradation
• Reduced Biodiversity
• Increased Disease Spread
• Trophic Cascades
• Example: Rabbits introduced to Australia decimated vegetation and displaced native wildlife.

• Hierarchy of Biological Organization
  • Individual
  • Population
  • Community
  • Ecosystem
  • Biome
  • Biosphere
• Describing an Organism’s “Place” in an Ecosystem
  • Habitat: The physical environment where an organism lives (like an address).
    *Niche: The organism’s role in the ecosystem (like a job description).