comunity interactions

COMMUNITY INTERACTIONS

• Elaborately Constructed Forms

  • Quote by Charles Darwin:

  • “These elaborately constructed forms, so different from each other, and dependent upon each other.”

  • Quote by Dacher Kelter, professor of psychology at UC Berkeley:

  • “Various forms of life, we are now learning, from the DNA in our cells to the individuals in our communities, are perpetually engaged in mutual influence, interdependent collaboration, and cooperation.”

SPECIES IN COMMUNITIES

• Population

  • Definition: Species living in a habitat.

• Community

  • Definition: All populations in a habitat.

• Habitat

  • Definition: Species place of residence.

• Niche

  • Definition: Species occupation, encompassing activities, resources used, and interactions.

COMMUNITY STRUCTURE

• Influences on Community Structure

  • Abiotic Characteristics:

  • Climate

  • Topography

  • Temperature

  • Rainfall

  • Soil Types

  • Physical Disturbances

ECOSYSTEMS

• Definition of Ecosystem:

  • An ecosystem includes the community of living things in a particular location and the nonliving environment with which they interact in that location.

• Features of the Nonliving Environment:

  • Physical conditions such as:

  • Temperature

  • Moisture

  • Light

  • Chemical resources found in soil, water, and air.

• Example of an Ecosystem: North American Prairie

  • Characteristics:

  • Abundance of grasses

  • Variety of animals

  • Historical presence of bison with restoration efforts noted.

• Living (Biotic) & Nonliving (Abiotic) Factors in the Prairie Ecosystem:

  • Biotic Factors:

  • Grasses with robust root systems

  • Various species of animals:

    • Elk

    • Bison

    • Golden eagle

    • Pollinators

    • Burrowing mammals: prairie dog, pocket gopher, etc.

    • Birds: prairie chicken, red fox, etc.

    • Reptiles: Rattlesnake

    • Amphibians: Great Plains toad

    • Insects: Grasshopper, pollinators

  • Abiotic Factors:

  • Air (CO₂, weather)

  • Soil nutrients

  • Light

  • Fire

  • Grazing

  • Burrows

  • Wallowing depressions

COMMUNITY STRUCTURE

• Overall Structure Influences:

  • Available resources

  • Resource competition

  • Competitive Exclusion:

    • Definition: One species outcompetes another for resources.

  • Resource Partitioning:

    • Definition: Species adapt to different niches to reduce competition.

• Types of Species Based on Resource Utilization:

  • Generalists:

  • Definition: Feed on a variety of resources.

  • Specialists:

  • Definition: Feed on specific types of resources.

RESOURCE COMPETITION EXAMPLES

• Competition between Species:

  • Western Honey Bees (Apis mellifera) vs. African Honey Bees (Apis mellifera scutellata)

  • Outcome: Competitive exclusion; African honey bees use aggression to dominate flower resources.

  • Western Honey Bees vs. Blueberry Bees (Osmia ribifloris)

  • Outcome: Resource partitioning; Blueberry bees are specialized to feed on blueberry flowers, honey bees utilize a range of flower types.

    • Generalists Adaptation:

    • Forage over great distances, feeding on multiple flower types.

    • Specialist Adaptation:

    • Efficient in a niche with specific food sources.

COMMUNITY STRUCTURE CONTINUED

• Population Dynamics:

  • Changes in population sizes

  • Arrivals and disappearances of species

  • Various interactions between species

SPECIES INTERACTIONS

• Types of Interactions:

  • Commensalism

  • Mutualism

  • Interspecific Competition

  • Predation

  • Parasitism

COMPONENTS OF ECOSYSTEMS

• Basic Components:

  • Habitats

  • Biotic Factors

  • Abiotic Factors

  • Communities

ENERGY FLOW IN FOOD CHAINS

• Energy Transfer in Food Chains:

  • Energy flows unidirectionally from producers to consumers.

  • Energy efficiency is low, with only 10% of energy being transferred to the next trophic level.

  • Energy Pyramid Visual:

    • Producers: 100% energy captured from the sun

    • Primary Consumer (Herbivore): 10% energy

    • Secondary Consumer (Carnivore): 1% energy

    • Energy Losses:

    • 90% is lost through metabolism, heat, and waste.

PHOTOSYNTHESIS AND ENERGY CAPTURE

• Processes Utilized in Energy Transfer:

  • Photosynthesis:

  • Captures energy from sunlight.

  • Eating (Energy Transfer):

  • Transfer of energy occurs through food consumption.

• Physical Law Implications:

  • Energy transfer is never 100% efficient, and there is a continual requirement for energy input from the sun for sustaining life on Earth.

FOOD WEBS AND CHAINS

• Food Webs Definition:

  • Composed of multiple intersecting food chains illustrating complex feeding relationships in a community.

  • Arrows indicate the eating direction in relationships.

• Food Chains Definition:

  • A linear sequence of feeding relationships.

  • Classification of individuals into trophic levels based on their position within the chain.

BIOMES

• Definition of Biomes:

  • Large geographic areas defined by specific plant life and composed of various ecosystems.

  • Factors determining biomes include temperature and moisture levels.

• Examples of Biomes:

  • Tropical Forest:

  • Characterized by warm temperatures and sufficient rainfall.

  • Savanna:

  • Warm temperatures, with dry and rainy seasons; primarily grass land with some trees.

  • Taiga:

  • Evergreen trees, long cold winters, short summers.

  • Tundra:

  • Low-growing vegetation, permafrost present.

  • Temperate Grassland:

  • Mainly perennial grasses, includes prairies of North America.

  • Desert:

  • Characterized by extreme dryness.

  • Aquatic Biomes:

  • Covering vast areas of Earth, includes marine and freshwater environments.