Ecology Exam 2

Flashcards covering key vocabulary and concepts related to population growth.

Geometric Growth

A type of population growth that occurs when generations do not overlap, modeled using a specific formula.

Exponential Growth

Continuous population growth in an unlimited environment; characterized by increasing growth rates as population size increases.

Logistic Population Growth

A model of population growth that slows as resources are depleted, represented by an S-shaped curve.

Carrying Capacity (K)

The maximum number of individuals of a population that an environment can support.

Density-dependent factors

Factors that limit population growth based on population size, such as disease and resource competition.

Density-independent factors

Factors that limit population growth regardless of population size, such as natural disasters.

Intrinsic Rate of Increase (r)

The maximum per capita rate of increase of a population when ideal conditions are met.

Sigmoid Curve

The S-shaped curve representing logistic population growth.

Demography

The statistical study of populations, including the structure, distribution, and trends.

Rinder pest

A disease that affected cattle and their relatives, impacting the buffalo population in the Serengeti.

Whooping crane

A species whose population grew exponentially from 15 to over 180 since its protection in 1940.

Marine Pelagic Tunicates

Organisms that grow at exponential rates in response to phytoplankton availability.

Age Distribution

The composition of a population categorized by different age groups, indicative of population stability or growth.

Adaptive advantage of manipulation

Increases parasite reproduction and transmission success

Advantage of masting

Predators cannot consume all seeds, increasing survival rate

Arbuscules

Branching fungal structures inside roots where nutrient exchange occurs

Benefits to fungi from mycorrhizae

Receive carbohydrates and sugars produced by the plant through photosynthesis

Benefits to plants from mycorrhizae

Increased absorption of water and nutrients like phosphorus and nitrogen

Biological control

Use of natural predators or parasites to manage pest populations

Bottom-up control

Population regulation driven by food availability and resources

Cactus-moth example

Cactoblastis moth introduced to Australia reduced invasive prickly pear cactus dramatically

Causes of hare decline

Predation, starvation, disease, and physiological stress

Cicada emergence strategy

Mass emergence every 13-17 years overwhelms predators

Cicada survival outcome

Only a small percentage are eaten despite large predator presence

Context dependency

Strength of mutualism changes based on environment and resource availability

Cost-benefit relationship

If nutrients are abundant, plants may rely less on fungi

Density-dependent factors

Factors like predation, disease, and food that intensify as population density increases

Dilution effect

Each individual has a lower chance of being eaten in a large group

Effect of mutualism on energy use

Allows plants to invest more in photosynthesis and growth

Effect of mycorrhizae on water

Plants with fungi maintain higher water potential and resist drought better

Energy allocation in plants

Plants balance energy between roots and above-ground growth

Example of parasite manipulation

Parasites alter host behavior to increase transmission to next host

Exploitation

Interaction between species where one organism benefits while the other is harmed (reduced fitness)

Exploitation and population size

Predators and parasites can regulate or reduce prey/host populations

Facultative mutualism

Mutualism that is beneficial but not essential for survival

Fitness (ecology)

An organism's ability to survive and reproduce in its environment

Gause experiment

Showed predator-prey cycles require specific conditions like refuges

Importance of refuges

Allows prey populations to survive and prevents extinction

Laboratory predator-prey experiments

Often result in extinction due to lack of environmental complexity

Limitation of models

Do not account for all real-world factors like environment, disease, and multiple species

Lotka-Volterra model

Mathematical model predicting oscillations in predator-prey populations

Low profitability prey

Large or difficult prey may be ignored by predators

Mantle

Dense layer of fungal tissue surrounding plant roots

Masting

Synchronous production of large numbers of seeds to reduce predation

Mechanism of improved water uptake

Fungi extend root system and increase surface area for absorption

Mutualism

Interaction between species where both organisms benefit

Mutualistic balance

Net benefit of mutualism depends on environmental conditions

Mycorrhizae

Symbiotic relationship between plant roots and fungi that enhances nutrient and water uptake

Mycorrhizal advantage in poor soils

Fungi supply limiting nutrients more efficiently than roots alone

Nutrient-poor environments

Conditions where essential nutrients like nitrogen and phosphorus are limited

Obligate mutualism

Mutualism that is required for survival of one or both species

Optimal foraging theory

Predators choose prey that gives the most energy for least effort

Overgrazing effect

Hares overconsume plants, leading to reduced food availability

Parasite-host interaction

Relationship where parasite depends on host for nutrients while harming host fitness

Parasitism

Interaction where a parasite lives on or in a host and harms it without usually killing it

Parasitoid

An organism (often insect larvae) that lives in/on a host and eventually kills it

Pathogen

Disease-causing organism such as bacteria, viruses, or fungi

Plant defense mechanism

Plants increase chemical defenses after heavy herbivory, making them less edible

Plant response to low nutrients

Increased investment in root growth and symbiotic relationships

Plant water potential

Measure of water status in plants; higher values indicate better hydration

Population cycle

Regular rise and fall in population size over time

Population oscillations

Cyclical fluctuations caused by interactions between predator and prey populations

Predation

Interaction where a predator kills and consumes its prey

Predation impact on hares

Predators can account for up to 60-98% of hare mortality during peak populations

Predation pressure

Impact predators have on reducing prey populations

Predator satiation

When prey overwhelm predators by sheer numbers

Protection in numbers

Group living reduces individual risk of predation

Puccinia fungus effect

Infects plants and creates bright yellow pseudo-flowers to attract pollinators and spread spores

Refuge (ecology)

Area or condition that protects prey from predators

Refuge experiment example

Adding shelter allowed prey to persist and populations to cycle

Role of food availability

Limited food supply reduces survival and reproduction of prey populations

Size as a refuge

Larger body size reduces likelihood of being preyed upon

Snowshoe hare-lynx cycle

Classic predator-prey cycle where increases in hares lead to increases in lynx, followed by declines in both

Spatial refuge

Hiding places created by environmental structure

Top-down control

Population regulation driven by predators

Ro>1

Population is ncreasing

Ro=1

Population is stable

Ro<1

Not replacing current population

Type 3 Survivalship

Low maternal rate, not dying out, high birthrate (sometimes dying after birth typically salmon)

Type 1 Survivorship

High maternal rate, low offspring, more stable, (mammals)

Type 2 Survivorship

Equal maternal care to offspring ratio, old individuals will die off faster (birds)