Population Dynamics and Growth Fundamentals

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Questions and Answers

Why don't populations of organisms grow indefinitely?

Limiting factors affect survival rates. Exceeding carrying capacity reduces populations.

The number of organisms of one species that an environment can support is called its _____.

Carrying capacity

If the number of organisms in a population is _____ the environment's carrying capacity, births _____ deaths and the population _____.

Under; exceed; grows

If the number of organisms rises _____ the carrying capacity of the environment, _____ will exceed _____.

<p>Above; deaths; births</p> Signup and view all the answers

This pattern will continue until the population is once again at or _____ the carrying capacity.

<p>Below</p> Signup and view all the answers

The most important factor that determines population growth is the organism's _____.

<p>Reproductive pattern</p> Signup and view all the answers

What do organisms that follow a rapid life-history pattern do?

<p>They have short life spans, have small bodies, and reproduce early.</p> Signup and view all the answers

What do organisms that follow a slow life-history pattern do?

<p>They reproduce slowly.</p> Signup and view all the answers

A limiting factor that has an increasing effect as population size increases is _____.

<p>Competition</p> Signup and view all the answers

Explain how the lynx population size changes when the hare population increases.

<p>Hare population goes up which means more food for the lynx population. The lynx population then goes up as well.</p> Signup and view all the answers

Explain how the change in the lynx population size affects the hare population.

<p>The lynx population goes up which causes the hare population to go down.</p> Signup and view all the answers

What is the relationship between the lynx and the hare called?

<p>Predator-prey relationship</p> Signup and view all the answers

When does competition decrease the size of a population?

<p>When demand for resources exceeds supply.</p> Signup and view all the answers

What can cause an organism to exhibit stress, and what symptoms of stress can lead to a decrease in population size?

<p>When populations of organisms become overcrowded, individuals may exhibit stress. Symptoms include aggression, decrease in parental care, decreased fertility, and decreased resistance to disease.</p> Signup and view all the answers

What is a population?

<p>A group of organisms of one species that interbreed and live in the same place at the same time.</p> Signup and view all the answers

What is a simple way for a biologist to study population growth?

<p>Bacterial cultures in a petri dish.</p> Signup and view all the answers

How is population growth different than growth of job income?

<p>No linear growth, grows exponentially first.</p> Signup and view all the answers

What is exponential growth?

<p>Rapid growth as population increases which doubles in a fixed period of time.</p> Signup and view all the answers

Can biological populations grow exponentially?

<p>True (A)</p> Signup and view all the answers

What does a graph of an exponentially growing population look like?

<p>J-shape, sleep, creep, leap</p> Signup and view all the answers

What is carrying capacity?

<p>Population size the environment can support.</p> Signup and view all the answers

Name 4 abiotic factors that affect carrying capacity.

<p>Water, sunlight, nutrients, and oxygen.</p> Signup and view all the answers

Name 4 biotic factors that affect carrying capacity.

<p>Food, predation, competition, and parasites.</p> Signup and view all the answers

How does birth rate compare to death rate when a population is under carrying capacity? Over carrying capacity?

<p>When births are lower than deaths under carrying capacity, the population increases. When births are over deaths over carrying capacity, the population decreases.</p> Signup and view all the answers

Describe organisms that have a rapid life history. Give 2 examples.

<p>Rapid life-history patterns are found in organisms from unpredictable environments. Typically, these organisms have a small body size, mature rapidly, reproduce early, and have a short life span. Bacteria and rabbits would be two examples of this.</p> Signup and view all the answers

Describe organisms that have a long life history. Give 2 examples.

<p>Species that live in more stable environments, such as elephants, often have a different life-history pattern. Humans, bears, whales, and long-lived plants are large, reproduce and mature slowly, and are long-lived. These organisms maintain population sizes near the carrying capacities of their environments. Elephants and humans would be two examples of this.</p> Signup and view all the answers

What is a density-dependent factor? Give 3 examples.

<p>It includes disease, competition, parasites, and food. These have an increasing effect as the population increases. Food supply, competition, and parasites would be 3 examples of this.</p> Signup and view all the answers

What is a density-independent factor? Give 3 examples.

<p>They affect all populations, regardless of their density. Most are abiotic factors, such as temperature, storms, floods, drought, and habitat disruption. Another example would also be pollution. Temperature, storms, floods, and drought are some examples of this.</p> Signup and view all the answers

How does predation affect population? Give an example.

<p>When a predator consumes prey, it can affect the population size of the prey population. An example would be a swarm of locusts eats and destroys acres of lettuce on a farm.</p> Signup and view all the answers

How does competition affect population? Give an example.

<p>When only a few individuals compete for resources, no problem arises. When a population increases to the point at which demand for resources exceeds the supply, the population size decreases.</p> Signup and view all the answers

How does crowding and stress affect population? Give an example.

<p>As populations increase in size, individual animals begin to exhibit a variety of symptoms, including aggression, decrease in parental care, decreased fertility, and decreased resistance to disease.</p> Signup and view all the answers

Flashcards

Carrying Capacity

The maximum number of organisms an environment can support due to limiting factors.

Population Growth (under carrying capacity)

When birth rates exceed death rates, leading to population growth.

Population Decline (over carrying capacity)

When death rates exceed birth rates, causing the population to decline.

Rapid Life-History Organisms (R-strategists)

Organisms with short lifespans, small body sizes, and early reproduction. They thrive in unpredictable environments.

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Slow Life-History Organisms (K-strategists)

Organisms that reproduce slowly and often have longer lifespans. They thrive in stable environments.

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Competition

A density-dependent limiting factor that intensifies as population size increases. It occurs when resource demand exceeds supply.

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Predator-Prey Relationship

An interaction where one population (predator) consumes another (prey), influencing both populations.

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Population

A group of interbreeding organisms of the same species sharing the same habitat.

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Exponential Growth

A growth pattern characterized by rapid population increases that double during fixed time intervals, resulting in a J-shaped curve.

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Abiotic Factors (Affecting Carrying Capacity)

Non-living factors like water, sunlight, nutrients, and oxygen that influence carrying capacity.

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Biotic Factors (Affecting Carrying Capacity)

Living factors like food availability, predation, competition, and parasites that influence carrying capacity.

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Density-Dependent Factors

Factors (e.g., disease, competition) that have a greater impact as population size increases.

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Density-Independent Factors

Factors such as temperature, storms, and floods that impact populations regardless of density, often abiotic.

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Crowding and Stress (Population)

Stress-related behaviors among individuals due to high population density, leading to aggression, reduced parental care, lower fertility, and increased disease susceptibility.

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Study Notes

Population Growth Fundamentals

  • Populations cannot grow indefinitely due to limiting factors which impact survival rates.
  • Carrying capacity defines the maximum number of organisms an environment can support.

Population Dynamics

  • When a population is under carrying capacity, birth rates exceed death rates, leading to population growth.
  • Conversely, if a population exceeds carrying capacity, death rates surpass birth rates, causing decline.
  • The population will stabilize at or below carrying capacity.

Reproductive Patterns

  • Organisms' reproductive patterns significantly influence population growth.
  • Rapid life-history organisms have short lifespans, small body sizes, and reproduce early.
  • Slow life-history organisms tend to reproduce slowly and often have longer lifespans.

Limiting Factors

  • Competition is a density-dependent limiting factor that intensifies as population size increases.

Predator-Prey Relationships

  • Snowshoe hares serve as a primary food source for Canadian lynx; an increase in hare population leads to an increase in lynx population, while a rise in lynx results in a decrease in hare population.
  • This interaction exemplifies a predator-prey relationship.

Competition and Stress

  • Competition decreases population size when resource demand exceeds supply.
  • Overcrowding can induce stress in populations, leading to aggression, reduced parental care, lower fertility, and increased disease susceptibility.

Defining Populations

  • A population consists of a group of organisms of the same species that interbreed and share the same habitat.

Studying Population Growth

  • An effective method for analyzing population growth involves using bacterial cultures in petri dishes.

Growth Patterns

  • Biological populations can exhibit exponential growth, characterized by rapid increases that double during fixed time intervals.
  • A typical graph of exponential growth shows a J-shaped curve, reflecting slow, steady, and then rapid growth phases.

Factors Affecting Carrying Capacity

  • Factors that influence carrying capacity include:
    • Abiotic: Water, sunlight, nutrients, oxygen.
    • Biotic: Food availability, predation, competition, parasites.

Birth and Death Rates

  • When a population is under carrying capacity, the birth rate surpasses the death rate. When over, the situation reverses.

Life History Strategies

  • Rapid life-history organisms (R-strategists): thrive in unpredictable environments, e.g., bacteria and rabbits.
  • Long life-history organisms (K-strategists): thrive in stable environments, e.g., humans, elephants, and whales.

Density-Dependent and Density-Independent Factors

  • Density-dependent factors (e.g., disease, competition) become more impactful as population size increases.
  • Density-independent factors (e.g., temperature, storms, floods) impact all populations regardless of density, often abiotic in nature.

Effects of Predation

  • Predation can significantly affect prey populations. For instance, locusts devastate crops by consuming all available lettuce.

Impact of Competition

  • Increased population results in higher competition for limited resources, potentially leading to decreased population sizes.

Crowding and Stress

  • Crowding can result in stress-related behaviors among individuals, contributing to various negative effects on population health and viability.

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