Populations and Communities

Flashcards about Populations and Communities, including ecosystems, interactions, and population dynamics.

What is an ecosystem?

Ecosystems are made up of complex interactions between organisms and their environment, where components interact and are dependent on each other.

What new properties arise as the number of individuals and number of species increase in a community?

Cooperation and competition, herbivory and predation.

What factors can limit populations or decrease their numbers?

Food, water, presence of predators and the introduction of diseases.

What is a population in biology?

A group of individuals of the same species living in the same geographical area at the same time and able to interbreed.

What characteristics can be used to describe a population?

Population size, population density, geographical distribution, and the maximum number of individuals that can be supported by the resources available.

What's the difference between systematic and random sampling?

Systematic sampling involves measurements at specified, regular intervals, while random sampling involves arbitrarily chosen zones.

What is sampling error?

The difference between an estimated population size and the true size of the whole population.

What is a quadrat?

A square of a particular dimension used to ensure the surface area of the sample size is the same for each count.

When is the capture-mark-release-recapture method used?

Estimate population size for motile organisms.

What is the Lincoln index formula for estimating population size?

M × N/R, where M is the number of individuals caught and marked initially, N is the total number of individuals recaptured and R is the number of marked individuals recaptured.

What is a key assumption of the capture-mark-release-recapture method?

No immigration or emigration.

What is carrying capacity (K)?

The maximum number of individuals that a particular habitat can support.

What are limiting factors that define the carrying capacity of a habitat?

Availability of resources, build-up of waste, predation, and disease.

What is the difference between density-dependent and density-independent factors?

Density-dependent factors influence populations based on their density, while density-independent factors affect populations regardless of density.

What is the difference between positive and negative feedback in population dynamics?

Positive feedback increases the population, while negative feedback prevents a system from going too far in one direction.

What are the three stages of population growth represented by a sigmoid curve?

The exponential phase, the transitional phase, and the plateau phase.

What are the reasons for exponential growth in a population?

Plentiful resources, little competition, favorable abiotic factors, and little predation or disease.

What causes the transitional phase in population growth?

Increasing competition for resources, predators moving into the area, and increased spread of disease.

What factors lead to the plateau phase in population growth?

The area is already occupied, limited food supply, and increased mortality from predators and disease.

What is a community?

A group of populations living and interacting with each other in an area.

What can 'interacting' mean when describing a community?

Populations feeding on each other, providing vital substances, protection, or habitat.

What are intraspecific relationships?

Relationships between individuals of the same species, involving cooperation or competition.

What is intraspecific cooperation?

An individual helps another from the same species to assure the survival of the individual and the group.

What is intraspecific competition?

Members of the same species compete for the same resources.

What are categories of interspecific relationships within communities?

Herbivory, predation, interspecific competition, mutualism, parasitism, and pathogenicity.

What is herbivory?

Eating plant material.

What is predation?

Killing and eating prey or eating something that has recently died (scavenging).

What is Interspecific competition?

Two species struggle to get the same food resource.

What is Mutualism?

Two species providing food or other resources where both benefit.

What is Parasitism?

One species living on or in a host and depending on the host for food for at least part of its life cycle. The host can be harmed by the parasite

What is Pathogenicity?

The ability of microbes such as bacteria and viruses to cause disease in other species

What organisms make up lichens and have a mutualistic relationship?

An alga providing food using photosynthesis and a fungus providing minerals.

How do parasites belonging to the genus Plasmodium cause malaria in humans?

They reproduce in the human liver and red blood cells.

What is mutualism?

A type of interspecific cooperation that benefits both species.

What are three examples of mutualism?

Plant root nodules and bacteria, mycorrhizae in Orchidaceae, and zooxanthellae in hard corals.

What is one genus of bacteria that can fix nitrogen?

Rhizobium.

How do Rhizobium bacteria benefit plants?

The bacteria convert nitrogen gas from the air into ammonia (NH3), an organic molecule that acts as a fertilizer for plants, helping them grow better.

What helps create Mycorrhizae in Orchidaceae?

Species of orchids rely on fungi for one or more stages of their life cycle.

How to coral polyps benefit zooxanthellae?

Coral polyps give the zooxanthellae carbon dioxide and minerals, which they need to photosynthesize and grow.

What is an endemic species?

A species is considered to be endemic in an area if it is only found there and nowhere else in the world.

What are invasive species?

Species that have been introduced into a new area from a distant origin and their populations grow so well that they start to cause problems for the species that are already living there.

What indicates Interspecific competition?

Tests for interspecific competition are indicated but not proven if one species is more successful in the absence of another.

How can hypotheses be tested?

Hypotheses can be tested by both experiments and observations and should understand the difference between them.

Give an example of Correlation (two phenomena are connected; when one happens, the other happens).

Night follows day.

What is the chi-squared test of association used for?

Statistical test used to see whether two species tend to occur together more often than they would by chance or if, on the contrary, they are never found coexisting or at least less frequently than would be expected by chance.

What is the null hypothesis for the chi-squared test?

The null hypothesis is that "the two categories (species 1, the goldenrod, and species 2, the aster) are independent of each other".

What factors affect large populations and small populations differently?

Density-dependent factors, such as food shortages, predation, and disease.

How are The Canada lynx (Lynx canadensis) and the snowshoe hare (Lepus americanus) are often cited as a classic example of a predator-prey interaction

Changes in the numbers of the lynx population are followed by changes in the numbers of the hare population.

What is the difference between top-down and bottom-up controls in communities?

Predation is a top-down control; scarcity of resources is a bottom-up control.

What are secondary metabolites?

Molecules produced to impede or kill competitors.

What is Allelopathy?

The production of secondary metabolites that influence the growth and success of other organisms.

What molecule does Garlic mustard produce?

Sinigrin.

How does Penicillium rubens use allelopathy in microbes?

In nature, this means that P. rubens can compete for space and food sources by releasing the allelopathic molecule penicillin into its surroundings.