ECOLOGY

What is predation?

A type of species interaction where one organism (the predator) feeds on another (the prey).

What happens to predator and prey populations over time?

They cycle together; for example, snowshoe hares and lynx in Canada peak in population every 10 years.

What do carnivores eat?

Animals.

What do herbivores eat?

Plants, often specializing in certain species.

What do omnivores eat?

Both plants and animals.

What is the Optimal Foraging Theory?

Describes how predators choose prey based on encounter rate and handling time.

What are generalist predators?

Predators that eat many different prey species.

What are specialist predators?

Predators that focus on a few specific prey.

Give an example of an active searching predator.

Wolves tracking a herd of elk.

Give an example of a sit-and-wait predator.

Spiders weaving webs to catch insects.

What are some physical defenses prey use against predators?

Large size, fast speed, agility, armor, and shells.

What is aposematic coloration?

Bright colors that signal toxins (e.g., poison dart frogs).

What is crypsis?

Camouflage that allows an organism to blend into the environment.

What is mimicry in prey defense?

When a harmless species looks like a dangerous or toxic species.

How do some prey animals avoid being eaten in groups?

By herding or schooling.

What is a behavioral defense some animals use?

Playing dead to avoid attack.

What are structural defenses in plants?

Spines, thorns, tough leaves, or tiny hairs.

What are chemical defenses in plants?

Toxins that make plants taste bad or poisonous.

What is an induced defense in plants?

Defenses that increase only after being attacked, such as cacti growing more spines.

What does the Lotka-Volterra Model explain?

How predator and prey populations rise and fall in cycles.

What happens when prey numbers increase according to the Lotka-Volterra model?

Predator numbers grow due to more food availability.

What may happen if predators increase too much?

Prey numbers drop as predators eat too many.

How does the predator-prey cycle ultimately repeat?

Fewer predators allow prey populations to recover, continuing the cycle.

What characterized the mites in the lab experiment?

Predators that easily found prey led to prey extinction.

What role do parasites play in a parasitic relationship?

Parasites benefit at the expense of the host.

What is the difference between macroparasites and microparasites?

Macroparasites are large (e.g., ticks), while microparasites are small (e.g., bacteria).

What are ectoparasites?

Parasites that live outside the host.

What are endoparasites?

Parasites that live inside the host's body.

How do some parasites manipulate host behavior?

By altering behavior to increase their transmission to new hosts.

What is an example of a multi-host parasite?

Trematodes that have complex life cycles involving snails, fish, and birds.

What does S represent in disease spread equations?

Susceptible individuals.

What does I represent in disease spread equations?

Infected individuals.

What does β represent?

The transmission rate.

What does m represent in disease spread equations?

The death and recovery rate of infected individuals.

What is the threshold density (ST)?

The minimum number of susceptible hosts needed for a disease to spread.

How can disease spread be controlled?

By reducing susceptible individuals or increasing recovery rates.

What role do parasites play as biodiversity indicators?

Some parasites can indicate ecosystem health and biodiversity levels.

What type of competition occurs within the same species?

Intraspecific competition.

What type of competition occurs between different species?

Interspecific competition.

What is exploitation competition?

Indirect competition by consuming shared resources.

What is interference competition?

Direct interactions between individuals such as aggressive behaviors.

What does a niche refer to?

The role an organism plays in its environment.

What is the competitive exclusion principle?

Two species using the same resource cannot coexist indefinitely.

What is resource partitioning?

Species adapt to use different resources or the same resource in different ways.

What is character displacement?

Evolutionary changes in traits that reduce competition and allow coexistence.

What are the key variables in the Lotka-Volterra competition model?

K (carrying capacity), N (population size), r (rate of increase), α, β (competitive effects).

What is the importance of keystone species?

They have a disproportionate effect on community structure.

What is mutualism?

A positive interaction where both species benefit.

What is commensalism?

An interaction where one species benefits, and the other is unaffected.

What is facilitation in ecology?

One species helps another, often in stressful environments.

What are obligate mutualisms?

Mutualistic interactions essential for survival.

What are facultative mutualisms?

Optional interactions where species can survive without each other.

What do zooxanthellae provide corals?

Enhanced growth, energy, and oxygen through photosynthesis.

What do corals provide for zooxanthellae?

Nutrients and protection in a stable habitat.

What is the relative neighbor effect (RNE)?

It measures how the presence of neighbors affects a species' growth.

What is alternative stable states theory?

A community may develop into different stable states based on environmental conditions.

What is the significance of invasive species in communities?

They can alter native community composition and ecosystem functioning.

What is primary succession?

The process that occurs in lifeless areas.

What is secondary succession?

Happens after disturbances in areas where life previously existed.

What are the three models of succession according to Connell & Slatyer?

Facilitation, inhibition, tolerance.

What do ecosystem engineers do?

Modify environments in ways that benefit other organisms.

What factors can influence community composition?

Dispersal, recruitment, abiotic and biotic factors.

What does species richness refer to?

The number of different species in a community.

What is species evenness?

The relative abundance of different species in a community.

What is biodiversity?

Genetic, species, and ecosystem diversity.

What does the Shannon Index measure?

It is a mathematical measure of species diversity in a community.

What is the meaning of trophic facilitation?

One species indirectly benefits another by modifying the environment.

What is character displacement intended to do?

Allow species to coexist by reducing competition through differentiated resource use.

What are the effects of mutualisms on community diversity?

They increase species diversity and help maintain ecosystem stability.

What can happen to mutualistic relationships under changing environmental conditions?

They can cease or become competitive.

What is an important ecological role of keystone species?

They significantly influence community structure.

What is a foundation species?

Habitat-forming species that are crucial to maintaining ecosystem structure.

How does competition affect species distribution?

It shapes species distribution and can limit population growth.

What occurs in a competition hierarchy?

One species consistently outcompetes others for resources.

What characterizes facilitation in stressful environments?

One species helps another persist under challenging conditions.

What is the overall significance of mutualisms?

They provide survival benefits and drive evolution and biodiversity.