FPT Ecology

Introduction to Ecology

• Definitions and key concepts in the field of ecology.

Biotic and Abiotic Factors

• Ecology: The study of how living things interact with each other and their environment.

• Biotic Factors: Include all living things (e.g., other organisms).

  • Example: A trout feeds on small fish and invertebrates.

• Abiotic Factors: Include non-living things (e.g., temperature, pH, oxygen concentration).

  • Example: Trout live in freshwater with a specific temperature, pH, and oxygen concentration range.

Levels of Organization

• Organisms: Study of individual traits and adaptations.

• Populations: Groups of individuals of the same species in a geographical area.

• Communities: Interactions between different populations in the same area.

• Ecosystems: Interaction of biotic and abiotic factors in an area.

• Biosphere: Encompasses all ecosystems on Earth and global interactions.

Organizing Living Things in Their Environments

• Ecosystem: A community interacting with the non-living environment (air, water, etc.).

• Biosphere: The collective of all Earth’s ecosystems.

• Population: Many organisms of the same species in one area.

• Community: Different populations living and interacting in a shared area.

• Organism: Individual living entities.

Food Chains and Food Webs

• Producers (Autotrophs): Create their own food mainly through photosynthesis (with some exceptions like chemoautotrophs).

• Consumers (Heterotrophs): Organisms that eat other organisms for food.

  • A food chain shows the linear transfer of energy and nutrients from one organism to another.

  • A trophic level indicates the number of steps in a food chain from producers.

  • A food web illustrates interconnected and overlapping food chains.

Energy Loss in Trophic Levels

• Energy diminishes at each trophic level in ecosystems, affecting population sizes and species distribution.

Biomagnification and Bioaccumulation

• Biomagnification: Increasing concentration of substances (toxins) in organisms at higher levels of the food chain.

  • Example: Compounds like methylmercury, DDT, and PCBs are stored in fatty tissues, rather than excreted.

• Bioaccumulation: Accumulation of pollutants or toxins in an organism’s tissues throughout its lifespan.

• Illustrative Example of Biomagnification:

  1. Phytoplankton absorbs PCBs.

  2. Zooplankton eats phytoplankton.

  3. Herring eats zooplankton.

  4. Salmon eats herring.

  5. Large mammals (e.g., orca whales) eat salmon.

• Comparison of Bioaccumulation vs. Biomagnification: Different trends in contaminant levels over time.

Characteristics of Populations

Population Size and Density

• Population: A group of individuals of the same species in a defined geographical area.

  • Population Size: Total number of individuals of the same species in an area at a given time.

  • Population Density: Number of individuals per unit area or volume.

  • Formula: $D = \frac{N}{S}$

    • Example of crude density: e.g., 1 black bear per 5 km².

    • Ecological Density: The population density within usable area (excluding uninhabitable space).

  • Example: If 1 km² of habitat is a lake, then if we have 1 black bear for 4 km², ecological density would be $0.25 \text{ bears/km}^2$.

Calculating Population Density Examples

1. For porcupines in 12.1 km x 15.3 km area:

   • Crude density = $\frac{450}{185.13} = 2.43 \text{ porcupines/km}^2$.

   • Ecological density = $\frac{450}{(185.13 - 4.3)} = 2.49 \text{ porcupines/km}^2$.

2. For wolves with 0.0093 wolves/km² density in an area of 50 km x 150 km:

   • Calculation: $N = D \times S = (0.0093) \times (150) \times (50) = 69.75$; thus about 70 wolves live in that area.

Population Distribution Patterns

• Types of Distribution:

  1. Clumped: Individuals are found in groups (e.g., bat colonies, schools of fish).

  2. Uniform: Individuals are evenly spaced (e.g., nesting penguins).

  3. Random: Individuals are spread randomly.

• Factors Influencing Distribution Patterns:

  1. Distribution of vital resources (food, water).

  2. Interactions among community members (social factors).

Measurement of Population Characteristics

• Sampling Techniques: Used to estimate population size and density since direct counting is often impractical.

  • Indirect Indicators: Using tracks and droppings.

  • Transect Sampling: Counting occurrences along a defined path.

  • Quadrat Sampling: Counting all organisms in a defined area, then extrapolating.

  • Example: In three quadrats measuring 2m x 2m with 11, 18, and 24 ragweed plants, the density is $D = \frac{N}{S} = \frac{53}{12} = 4.4 \text{ ragweed/m}^2$ with area of 10,000 m² leading to population size $N = D \times S = (4.4)(10,000) = 44,000$.

Mark Recapture Method

• Process: Capture, tag, release individuals, then recapture to estimate population size based on ratio of marked to unmarked.

• Mark-Recapture Formula: $\frac{M}{N} = \frac{m}{n}$

  • Example: If the first sample is 26 fish marked and released, and the second sample of 21 fish includes 3 marked, then we can estimate $N = \frac{26 \times 21}{3} = 182$ fish.

Population Change

Factors Affecting Population Growth

• Death rates, birth rates, immigration, and emigration.

• Population Change Calculation:

  • Formula: change = (births + immigration) - (deaths + emigration)

  • Example with coyotes: Initial population 27; 8 pups born, 4 died, and 1 moved in.

    • Population Change: $8 + 1 - (4 + 0) = 5$; thus, population increased by 5.

Types of Populations

• Open Population: Influenced by births, immigration, deaths, and emigration.

• Closed Population: Only births and deaths affect it.

Rate of Population Growth

• Growth Rate Formula: $\frac{\text{change in population size}}{\text{change in time}}$

  • Example: Peregrine falcons increasing from 50 to 130 in 5 years:

    • Growth rate = $\frac{130 - 50}{5} = 16 \text{ falcons/year}$.

Per Capita Growth Rate

• Formula: $cgr = \frac{\Delta N}{N}$

  • Example calculating the per capita growth rate of coyotes:

    • Final population = 32; Ecological growth = \frac{32 - 27}{27} \times 100 ext{%} = 18.5 ext{%}.

Population Growth Models

Exponential Growth

• Characterized by ideal conditions without predators or resource limitations.

• Constant population increase with no defined breeding season.

• High biotic potential examples include yeast and humans.

Logistic Growth

• Initial exponential growth eventually stabilizes as it approaches carrying capacity (K).

• Carrying Capacity: The maximum number of organisms an environment can sustain.

  • Growth phases: lag phase, log phase, stationary phase, exceeding phase.

    • Excessive population can lead to a crash due to depletion of resources.

Life Histories and Populations

• Life histories provide quantitative measures to understand populations better:

  • Factors studied include:

    1. Age of sexual maturity

    2. Frequency of reproduction

    3. Offspring survival rates

    4. Fecundity: Average number of offspring produced by a female during her lifespan.

• Comparison of different species with examples of litter sizes and reproductive rates.

Survivorship Curves

Types of Survivorship Curves:

1. Type I: High survival rates of young; most die at old age (e.g., humans, large mammals).

2. Type II: Constant mortality rate across ages (e.g., many birds, reptiles).

3. Type III: High mortality in young; many offspring are born, but few survive (e.g., plants, most fish, insects).

r and K Selection Theory

r-Selection Strategy

• Characterized by:

  • Unstable environments

  • Small body size

  • Low energy investment per individual

  • Many offspring and early maturity

  • Type III survivorship

K-Selection Strategy

• Characterized by:

  • Stable environments

  • Larger body size

  • High energy investment into offspring

  • Fewer offspring with longer lifespans

  • Types I & II survivorship

Factors Regulating Natural Populations

Biotic Potential

• The maximum reproductive capacity under ideal conditions.

Limiting Factors

• Biotic Limiting Factors:

  • Intraspecific competition: Competition for resources within the same species.

  • Predation: Affects both predator and prey dynamics.

Allee Effect

• Phenomenon where low density leads to reproductive failures.

Minimum Viable Population Size

• Smallest number of individuals required to ensure the population can persist over time (the viability threshold).

Abiotic Limiting Factors

• Environmental factors limiting population growth such as temperature and pollutants.

Interactions Within Communities

Niches

• Definition: An organism's biological role and its interactions with abiotic and biotic resources in the environment.

Interspecific Competition

• Competition among species for the same resource.

  • Resource partitioning to reduce competition.

Predation

• One species killing and consuming another.

  • Predator-prey dynamics often result in population fluctuations.

Adaptations in Predators and Prey

Predators

• Adaptations:

  • Enhanced senses (vision, smell).

  • Specialized behaviors (e.g., stalking techniques).

  • Morphological traits (claws, jaws).

Prey

• Defensive adaptations:

  • Morphological traits (e.g., shells).

  • Behavioral adaptations (e.g., hiding).

  • Mimicry concepts (Batesian and Müllerian mimicry).

Symbioses

Types of Symbiotic Relationships

1. Mutualism: Both species benefit (e.g., oxpecker and eland).

2. Commensalism: One benefits, the other is unaffected (e.g., algae on turtles).

3. Parasitism: One benefits at the other’s expense (e.g., mosquitoes and humans).

Endangered Species

• Global Diversity Crisis: 1.5 million species identified, 10 to 80 million may exist; many species face extinction.

• Statistics: Over the years, increases in species at risk globally from 2000 to 2019; specific habitats more endangered (e.g., temperate grasslands).

• Status Levels in Canada:

  1. Extinct: No longer exists anywhere.

  2. Extirpated: No longer exists in Canada.

  3. Endangered: Close to extinction in Canada.

  4. Threatened: Likely to become endangered if changes do not occur.

  5. Special Concern: At risk due to declining numbers.

Factors Influencing Species Status

1. Size

2. Range

3. Diet

4. Fecundity

5. Human interactions

Causes of Species Decline

• Habitat degradation, pollution, overhunting, introduction of alien species, diseases.

Keystone Species

• Definition: An organism significantly impacting its ecosystem, essential for community stability. Their absence can lead to drastic ecosystem changes.