Population Dynamics and Density Factors

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Questions and Answers

What does the term 'carrying capacity' refer to in population ecology?

The maximum population size an environment can sustain (correct)

The rate of population growth in a given area

The distribution of individuals within a population

The birth and death rates in a specific population

Which characteristic of populations helps predict future growth or decline?

Sex ratio (correct)

Density

Distribution

Size

What is the main focus of community level interactions in ecological terms?

Global processes affecting the biosphere

Dynamics and evolution of a population

Interactions among and between species (correct)

Survival and reproduction of individual species

Which of the following is an example of a density-independent factor affecting populations?

Natural disasters Signup and view all the answers

What does population density indicate about a species?

How many individuals live within a certain area Signup and view all the answers

Which level of ecological complexity focuses on global processes such as air and water movement?

Biosphere Signup and view all the answers

What factor is NOT included in density-dependent factors affecting populations?

Weather patterns Signup and view all the answers

What does 'age structure' in a population help to determine?

Potential future growth or decline of the population Signup and view all the answers

Which of the following factors limits the growth of a population?

Competition for resources Signup and view all the answers

What is indicated by a sex ratio that is significantly unequal from 50:50?

Increased chances of extinction for the population Signup and view all the answers

What characterizes populations that follow an exponential growth model?

Growth occurs under ideal conditions with unlimited resources. Signup and view all the answers

In the logistic growth model, what does the symbol K represent?

Carrying capacity of the environment Signup and view all the answers

What shape does the population growth curve take in the logistic growth model?

S-shaped Signup and view all the answers

Which of the following is a characteristic of K-selected species?

They provide extensive parental care. Signup and view all the answers

Which outcome is most likely for R-selected species?

They often experience large population overshoots and die-offs. Signup and view all the answers

Which statement accurately describes density-independent factors impacting populations?

They are factors that do not change with population size. Signup and view all the answers

What factor primarily determines the number of offspring produced by a K-selected species?

Carrying capacity of their habitat Signup and view all the answers

What is a key difference between density-dependent and density-independent populations?

Density-dependent factors increase with population size, affecting growth rates. Signup and view all the answers

Which of the following examples relates to an R-selected species?

Mice Signup and view all the answers

What could be a consequence of overshoots in population growth?

Increased competition for resources Signup and view all the answers

What characterizes a Type I survivalship curve?

High survival rate with a significant number dying in old age Signup and view all the answers

What is the primary risk for small populations in metapopulations?

Higher likelihood of extinction due to inbreeding depression Signup and view all the answers

Which type of species is characterized by a low survival rate and high numbers of offspring?

R-selected species Signup and view all the answers

What role do corridors play in metapopulations?

They facilitate movement and gene flow between populations. Signup and view all the answers

Which interaction is involved in parasitism?

One species lives on or in another, rarely causing death Signup and view all the answers

What is a characteristic of the Competitive Exclusion Principle?

It states that two species competing for the same resource cannot coexist. Signup and view all the answers

Which symbiotic relationship is described by a predator-prey dynamic?

Predation Signup and view all the answers

What is a common consequence of inbreeding depression in small populations?

Impaired ability to adapt to environmental changes Signup and view all the answers

Which of the following is an example of a Type II survivalship curve?

Squirrels Signup and view all the answers

What does the term 'metapopulation' refer to?

Multiple populations that are genetically connected through corridors Signup and view all the answers

What factor significantly affects species richness as one moves away from the equator?

Latitude Signup and view all the answers

Which process is NOT one of the basic processes determining species distribution?

Migration Signup and view all the answers

How does habitat size influence species richness?

Larger habitats hold more species Signup and view all the answers

Which of the following is an implication of the Theory of Island Biogeography?

Conservation efforts are influenced by colonization and extinction rates Signup and view all the answers

What condition might cause a decline in species richness in isolated habitats?

Limited colonization opportunities Signup and view all the answers

Which of the following statements about species richness is false?

Species are evenly distributed across habitats Signup and view all the answers

Which event can dramatically affect rocky intertidal zone ecosystems?

Major storms that turnover rocks Signup and view all the answers

The distribution of species in aquatic ecosystems is largely influenced by what process?

Dispersal limitations Signup and view all the answers

What primarily influences the importance of colonization, speciation, and losses by extension?

Latitude, time, and habitat size Signup and view all the answers

Which statement accurately describes the relationship between species richness and time?

Longer existing habitats generally exhibit more colonization Signup and view all the answers

What type of ecological interaction benefits one species without affecting the other?

Commensalism Signup and view all the answers

Which of the following interactions involves one species benefiting at the expense of another?

Herbivory Signup and view all the answers

What is an example of a keystone species?

Honey bees Signup and view all the answers

What type of succession begins on newly exposed rock without any soil?

Primary Succession Signup and view all the answers

In which type of succession does soil remain intact even after a disturbance?

Secondary Succession Signup and view all the answers

Which species type has a role that is not abundant but is crucial to the ecosystem?

Keystone species Signup and view all the answers

What happens during secondary succession following a disturbance?

Pioneer species quickly grow due to remaining sunlight Signup and view all the answers

What is the primary difference between primary and secondary succession?

Primary requires soil formation from rock Signup and view all the answers

What happens when two species have the same realized niche?

One species will become dominant and可能驅趕另一種. Signup and view all the answers

During which ecological interaction do both species benefit?

Mutualism Signup and view all the answers

What is a classic example of commensalism in nature?

Trees and bird nests Signup and view all the answers

What is resource partitioning?

When species specialize in different resources due to behavioral or morphological differences. Signup and view all the answers

What type of predation is characterized by laying eggs in a host?

Parasitoidism Signup and view all the answers

Which of the following is NOT a type of pathogen that can cause disease in a host?

Plants Signup and view all the answers

Which defense type involves altering physical features to avoid predation?

Morphological defenses Signup and view all the answers

What effect can herbivores have on plant populations?

Can lead to extinction of common species. Signup and view all the answers

What type of symbiotic relationship is mutualism?

Both species benefit from the interaction. Signup and view all the answers

What outcome may occur if the benefits of mutualism decrease for one party?

Natural selection may favor a change in the relationship. Signup and view all the answers

What is the primary consequence of competition between two species sharing the same resource?

One may become extinct or relocate. Signup and view all the answers

Which of the following is an example of chemical defense in animals?

Emitting toxins to deter predators Signup and view all the answers

Study Notes

Abundance and Distribution of Populations

Populations are made up of individuals that interact, die, and are born, and move between populations.
Population size (N) is the total number of individuals in a given area.
Population density is the number of individuals per unit area at a given time, showing if a species is rare or common.
Population distribution describes how individuals are arranged in a habitat.
Sex ratio is the proportion of males to females, which is often 50:50 but can vary; it influences future populations.
Population age structures show the number of individuals in each age category, predicting future growth or decline.

Density Dependent Factors

Density-dependent factors limit population growth when population density is high.
Examples include resources like water, food, shelter and nutrients.
Limiting resources affect population sizes.
Carrying capacity (K) represents the maximum population size that an environment can support sustainably given the available resources.
Resources influence density-dependent populations while external factors such as weather do not necessarily.

Density Independent Factors

Density-independent factors affect populations regardless of their density and include weather patterns, natural disasters, and human-caused disturbances.
Population size is not a factor when considering population growth in consideration of density independent factors
These usually affect the carrying capacity.

Population Growth Models

Exponential growth occurs when resources are unlimited.
Populations grow at a fixed rate without any limitations, and under these conditions the growth rate is at its maximum potential.
Populations under ideal conditions, with unlimited resources, high birth rates, and low death rates would exhibit exponential growth and would grow continuously.
A J-shaped curve describes exponential growth.
Logistic growth accounts for carrying capacity.
It reflects the realistic scenario of limited resources.
Growth initially happens at a fixed rate but slows down as it reaches the carry capacity (K).
A logistic growth model is an S-shaped curve.

Reproductive Strategies

K-selected species have low intrinsic growth rates, produce few offspring, and provide parental care.
Elephants, humans, and other large mammals are examples of K-selected species.
R-selected species have high intrinsic growth rates, make a lot of offspring; but do not provide much parental care.
Mice, insects, and bacteria are examples of R-selected species.

Survivorship Curves

Survivorship curves show patterns of survival for individuals over their lifetime.
Type 1 curves show high survivorship early in life, then a decline in older age (larger animals).
Type 2 curves show a fairly constant rate of survival throughout life (small organisms).
Type 3 curves show low survivorship early in life, then high survivorship in older age (plants).

Metapopulations

Metapopulations are groups of populations connected by occasional movements.
Animals within a metapopulation may travel between habitats to maintain larger populations and genetic diversity, or even avoid extinction.

Community Ecology and Negative Effects

Community ecology focuses on interaction among multiple species.
Competitive interactions occur when individuals compete for the same resources; those who can best utilize resources will outcompete other organisms.
Predation is when one organism consumes another.
Parasitism benefits one organism (parasite) while harming the other (host); for example, tapeworm, and mosquito.
Herbivory is when an animal eats a plant.
Symbiosis describes close relationships between two species, like mutualism (both benefit), commensalism (one benefits, one is unaffected) and parasitism (one benefits, one is harmed).
The exclusion principle states that two species competing for the same resources cannot coexist.
Resource partitioning describes how similar species adapt to reduce competition and efficiently utilize resources.

Succession

Succession is the gradual change in a community of species over time.
Primary succession begins in an area with no soil (e.g., bare rock), colonizing barren locations.
Secondary succession begins in an area with existing soil (e.g., after a fire, flood, or a forest clearing).
Climax community is the stable, final stage of succession, where conditions are favorable for a particular combination of species.

Species Richness

Species richness refers to the number of species in a given area.
Higher species richness tend to be found at and near the equator
Factors include habitat area, isolation from other habitats (islands), and presence of human activity.

Island Biogeography

Extinction and colonization rates, immigration and emigration influence species richness of islands.

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Description

This quiz explores the abundance and distribution of populations, focusing on key concepts such as population size, density, and age structures. It also examines density-dependent factors that influence population growth and the carrying capacity of environments. Test your understanding of these fundamental ecological principles.