Population ecology

What is the definition of a species?

A species is a group of organisms with similar characteristics that can interbreed and produce fertile offspring.

Define individual

a single organism

What is population?

Population is a group of similar organisms of the same species living in the same place at the same time and interbreeding successfully to produce fertile offspring.

What is a community?

A community is a population of different species that inhabit and interact in a particular area.

What is an ecosystem?

An ecosystem is groups of different species of organisms that interact with each other and their environment.

What is an individual?

An individual is a single organism capable of independent existence.

What are population parameters?

Population parameters are represented by N (population size), M (mortality), I (immigration), and E (emigration).

What is a closed population?

A closed population is one where immigration (I) and emigration (E) are not included.

What is the lag phase?

The lag phase is the initial stage of population growth where organisms adapt to their environment, and growth is slow.

What is the log phase?

The log phase is a period of rapid, exponential population growth as resources are abundant.

What is the stationary phase?

The stationary phase is when population growth levels off as resources become limited and births balance deaths.

What is logarithmic growth?

Logarithmic growth is the exponential increase in population size during the log phase.

symbiotic relationship

close interaction between species in which one species lives in or on the other

N.I.M.E

Natality

Immigration

Mortality

Emigration

What is environmental resistance?

Environmental resistance is the total number of factors that stop a population from reproducing at its maximum rate.

What is carrying capacity?

Carrying capacity is the population density that the environment can sustainably support.

What is a stable population?

A stable population is one that oscillates around the carrying capacity once it is reached.

R strategies

large number of eggs, little investment of energy in offspring, little risk to the parents, but low survivor ship.

K strategies

few offspring, large investment of time and energy in offspring, survivor ship high. Parents ensure survival of fewer offspring by protecting the young from climatic extremes and predators, provision of food, shelter and etc.

Census

A complete enumeration of a population.

What is a population crash?

A population crash is a rapid and unstable decline in population size.

What are limiting factors?

Limiting factors are environmental components like water, space, and sunlight that restrict population growth.

What happens if a population exceeds the carrying capacity?

If a population exceeds the carrying capacity, disease will spread, space will become limited, and food will run out.

What is the mark-recapture method?

The mark-recapture method estimates population size by capturing, marking, and recapturing individuals. The formula is N = (C/R) × M, where M is the number marked, C is the captured sample size, and R is the recaptured marked individuals.

What is quadrat sampling?

Quadrat sampling involves dividing an area into quadrats, sampling randomly selected quadrats, and estimating population size by multiplying average density by the total number of quadrats.

What is a census?

A census is a direct count of individuals, typically used for large, visible, slow-moving, or stationary organisms, often in a small area.

How are aerial photography and helicopters used in population studies?

Aerial photography and helicopters are used to survey large areas and count large animals, such as elephants and buffalo.

What are indirect methods of population estimation?

Indirect methods include the Mark-Recapture method and Quadrat Sampling method.

What are the steps in the quadrat sampling method?

1. Measure the size of the total area. 2. Use a quadrat of known area. 3. Distribute quadrats randomly. 4. Count individuals in each quadrat and calculate the average per quadrat. 5. Use the formula: N = (number in sample × size of whole habitat) / area of quadrat.

What is exponential growth?

Exponential growth, also known as the J-shaped curve, is characterized by abundant resources, an unstable population, slow initial increase, and rapid later growth.

What prevents populations from growing indefinitely?

Limiting factors, also known as environmental resistance, prevent populations from growing indefinitely.

What is quadrat sampling?

Quadrat sampling involves estimating population size using random quadrats and the formula: N = (number in sample × size of whole habitat) / area of quadrat.

What is the S-shaped curve?

The S-shaped curve represents population growth that stabilizes over time, showing logistic growth.

What are the four phases of logistic growth?

1. Lag phase: Adjustment period. 2. Log phase: Rapid growth. 3. Decelerating phase: Slowing growth rate. 4. Equilibrium phase: Natality equals mortality.

What affects population size?

Population size is affected by population parameters (N, E, I, M), environmental resistance (resources and natural disasters), and competition and predation.

What is reliability?

Reliability means the experiment can be repeated, averaged, and requires a large sample size.

What is validity?

Validity means having controls in the experiment to ensure observed results reflect the relationship between dependent and independent variables.

What are the two survival strategies?

The two strategies are K-strategy (stable, slower reproduction, fewer offspring, parental care, long lifespan) and R-strategy (unstable, rapid reproduction, many offspring, no parental care, short lifespan).

What regulates population growth?

Population growth is regulated by changes in carrying capacity, density-dependent factors, density-independent factors, competition, and predation.

What are K-strategy species?

K-strategy species are stable, reproduce slowly, have fewer offspring, provide parental care, and have high survival rates of young.

What are R-strategy species?

R-strategy species are unstable, reproduce rapidly, have many offspring, do not provide parental care, and have high mortality rates.

What are density-dependent factors?

Density-dependent factors are environmental factors like competition for resources and disease that limit population growth as a result of population density.

What are density-independent factors?

Density-independent factors include natural disasters (earthquakes, floods) and environmental changes (temperature, rainfall) that affect populations regardless of their density.

What is density in population terms?

Density is the number of individuals per unit area.

What is competition?

Competition is a symbiotic relationship where species compete for the same resources.

What is predation?

Predation is a symbiotic relationship where one species, the predator, hunts and kills another species, the prey, for food.

What are intraspecific and interspecific competitions?

Intraspecific competition occurs between members of the same species, while interspecific competition occurs between members of different species.

What is competitive exclusion?

Competitive exclusion is a relationship where one species eliminates another species through competition for resources.

What is competitive co-existence?

Competitive co-existence is a relationship where species share resources to coexist peacefully.

What is resource partitioning?

Resource partitioning is when species share resources like food, light, and water by using different parts of the habitat or feeding at different times.

What is stratification?

Stratification is the arrangement of plants in a habitat, where taller plants take more light, and shorter plants like grass and ferns thrive underneath.

What is an ecological niche?

An ecological niche is a specific environment with all the necessary conditions for an organism to survive and reproduce.

What is a cyclic relationship in predator-prey dynamics?

A cyclic relationship is where prey decrease due to predator feeding, predators then decline due to less food, allowing prey to increase again.

What is primary succession?

It begins when we have a bare area of land with no growth.

What is secondary succession?

It results from a disturbance where all vegetation is dead, but the soil remains fertile, e.g., after a wildfire.

What happens during the pioneer species stage?

Early succession with bare conditions; durable species like bryophytes/moss establish rapidly and spread over long distances; they erode rocks, increasing nutrients.

What types of plants dominate in secondary succession?

Annuals like herbs, weeds, grasses, and climbers.

What fauna are considered pioneers in secondary succession?

Ants, mites, spiders, and herbivores.

What happens during the intermediate species stage?

Conditions stabilize, biodiversity increases, and woody plants, herbivores, and carnivores emerge.

What is the climax community stage?

It is the semi-stable endpoint of succession, determined by factors like rainfall, overgrazing, wetland drainage, and climate change.

How do group behaviors improve survival and reproduction?

They help avoid predator attacks, hunt as a pack, find mates, protect the colony, collect resources, and regulate population size.

What is the benefit of flocking?

Safety in numbers, more eyes watching for predators, mobbing predators, dilution effect, and confusing predators with scattering or distractions.

How does hunting as a pack increase efficiency?

Packs of 15+ individuals tire prey easily, immobilize prey by attacking together, and share the kill with young or non-hunting members.

What are the benefits of having a dominant breeding pair in a pack?

They keep the pack under control, maintain strong genetics, raise pups, care for the sick, and ensure resources and mates are shared by subordinates.

Flocking

Animals travel in groups for safety

Why is the human population size so large today?

Reduced environmental resistance and increased carrying capacity.

What are the characteristics of LDCs?

Rapid population growth and lower standards of living, e.g., many regions in sub-Saharan Africa.

What are the characteristics of MDCs?

Slow population growth and higher standards of living, e.g., countries like the USA and Germany.

What are the major groups in population demographics?

Pre-reproductive ages, productive ages, and post-reproductive ages.