Unit 6 - Interdependent Relationships in Ecosystems

Define and distinguish between levels in ecosystems.

Population: same species in one area; Community: many populations; Ecosystem: biotic + abiotic in one area.

Give examples of biotic and abiotic factors.

Biotic: humans, decomposers; Abiotic: water, rocks, pH, temp, light.

How do abiotic factors influence life in the biosphere?

Temp affects activity, water is essential, sunlight powers photosynthesis, soil affects growth, air is needed for respiration/photosynthesis, salinity affects aquatic life, climate controls ecosystems.

Define population and population ecology.

Population: same species in one place; Population ecology studies population changes and environmental interactions.

What do population ecologists study?

Growth rates, birth/death, immigration/emigration, environmental limits, and species interactions.

Define population density and types of dispersion.

Density = individuals per area; Types = Clumped, Random, Uniform.

How are life tables used?

Track survival/death by age to understand patterns.

Compare survivorship curves.

Type I: survive early, die old (humans); Type II: constant death (birds); Type III: early death, few survive long (insects).

Compare exponential vs logistic growth.

Exponential: fast, no limits (J-curve); Logistic: slows near carrying capacity (S-curve).

Define carrying capacity.

Max population an environment can support without harm.

What regulates population growth?

Limited food, space, predators, disease, competition.

What are boom-and-bust cycles?

Rapid growth followed by crash due to overuse, predators, disease (e.g. lynx/hare).

Define biological community and importance of community ecology.

Community = multiple populations; Ecology helps us understand interactions and ecosystem health.

Define mutualism, parasitism, competition, predation, herbivory.

Mutualism: both benefit (bee/flower); Parasitism: one benefits, one harmed (tapeworm); Competition: species fight for resources (lion/hyena); Predation: one eats another (wolf/deer); Herbivory: plant eaten (cow/grass).

What is an ecological niche and how does overlap cause competition?

Niche = species’ role; overlap = competition for same resources.

Describe coral-dinoflagellate mutualism.

Algae give coral sugars; coral gives algae light, home, nutrients.

Define predation and prey defense strategies.

Predation = one hunts/eats another; Defense: camouflage, mimicry, escape, warning color.

Why do plants have thorns, toxins, etc.?

To defend against herbivores.

Define coevolution with example.

Species evolve in response to each other (e.g., milkweed + monarch).

How do parasites/pathogens affect communities?

They reduce or shift species populations, altering balance (e.g., rinderpest affecting wildebeest).

Compare trophic levels in terrestrial vs aquatic food chains.

Producers (plants/phytoplankton), Primary (herbivores), Secondary (carnivores), Tertiary (top predators); aquatic chains flow faster.

How do food chains form food webs?

Food chains link to form complex webs showing all energy flows.

What is a keystone species? Give examples.

Species with big ecosystem impact; Sea star controls mussels; urchins control algae on reefs.

How does energy move through a food chain?

Energy flows up, but only ~10% transfers per level—rest is lost as heat.

Why are there more producers than consumers?

Loss of energy at each step means fewer consumers can be supported.

Why is eating meat a luxury?

Meat = less efficient; animals need lots of plants to grow.

What is a biome?

Large area defined by climate, soil, life (e.g., desert).

What is the biosphere?

All life + environments on Earth.

What is ecology?

Study of organism-environment interactions.

Define density-dependent factor.

Impact increases as population grows (e.g., disease).

Define density-independent factor.

Affects all populations equally (e.g., disasters).

What is intraspecific competition?

Same species compete for resources.

Define K-selection.

Few offspring, high care (e.g., elephants).

What is a life history strategy?

Traits that affect survival and reproduction.

Define r-selection.

Many offspring, little care (e.g., insects).

What is biomass?

Total living mass in an area.

What is a detritivore?

Animal eating dead material (e.g., worms).

What is detritus?

Dead plants and animals.

What is interspecific competition?

Different species compete.

Define interspecific interactions.

All interactions between different species.

What is a scavenger?

Eats dead animals (e.g., vultures).

What is trophic structure?

Feeding relationships in a community.

Define trophic cascade.

Top-level changes affect all lower levels in food web.