2.1 Individuals, Populations, Communities and Ecosystems

How can natural systems be modeled, and can these models be used to predict the effects of human disturbance?

Natural systems can be modeled to predict the effects of human disturbance.

Place these words in order from smallest to largest in scale: Population, Species, Community, Biosphere, Biome, Ecosystem.

Smallest to largest: Species, Population, Community, Ecosystem, Biome, Biosphere.

What is a species?

A group of organisms that can interbreed and produce fertile offspring.

What is the key characteristic that defines a species?

Species can interbreed to produce fertile offspring.

What is a population?

A group of organisms of the same species living in the same area at the same time, and which are capable of interbreeding.

What is a community?

A collection of interacting populations within the ecosystem.

What is an ecosystem?

A community and the physical environment with which it interacts.

What is the biosphere?

An ecological system composed of individuals, populations, communities, ecosystems.

What are biotic factors?

Living components of an ecosystem.

What are abiotic factors?

Non-living physical factors that may influence organisms.

Give examples of abiotic factors.

Temperature, sunlight, pH, salinity, dissolved oxygen, and soil texture.

Describe the effect of high salinity in the Dead Sea.

High salinity increases the density of the water and increases the buoyancy making it easier for objects to float, it also makes it difficult for life to exist

How is turbidity measured using a Secchi Disk?

A Secchi Disk is lowered into the water until it is no longer visible, and that depth is measured

Name the zones in an aquatic ecosystem.

Littoral, Limnetic, Benthic

How do populations interact in ecosystems?

Predation, herbivory, parasitism, mutualism, disease, and competition.

What are biotic factors?

Interactions between organisms - such as predation, herbivory, parasitism, mutualism, disease and competition.

What is Intraspecific Competition?

Competition between members of the same species.

What is Interspecific Competition?

Competition between members of different species.

Define Symbiosis.

An ecological relationship between organisms of two different species that live together in direct contact.

What are the three types of symbiosis?

Mutualism, commensalism, and parasitism.

What is Mutualism?

Both organisms benefit from the interaction.

What is Commensalism?

One organism benefits but the other is not harmed nor is benefitted.

What is Parasitism?

One organism benefits and the other is harmed.

Give an example of Community dependance for survival purposes.

Lion depends on the availability prey species, such as Zebra and Antelope

Explain the Predator-Prey Cycle.

As prey numbers swell, predators find an abundant food source. Increased food availability boosts the predator population, putting pressure on the prey

What is herbivory?

Primary consumer feeding on a plant or other producer.

What is parasitism?

A parasite is an organism that lives on or in a host and obtains food from it. The host is always harmed.

What is an exercise used to find biotic and abiotic factors found in South Africa using a Termite article.?

To determine three types of biotic interactions (termites engage in) and three abiotic factors that are key to termite survival.

What are limiting factors?

Factors that control the maximum size of a given population

Favorable conditions are desired by an organism of its home environment. Because of this, an animal must search for the environment to fit its structure and lifestyle. What is this process called?

A habitat selection

What method is used to estimate population abundance?

Random sampling, systematic sampling, or transect sampling

How do the Prey Population and Predator's Population interact.

High number of prey as predator population decreases. More prey so predators increase, etc.

Define a sample.

A part of a population, part of an area or part of some other whole thing, chosen to illustrate what the whole population, area or other thing is like.

What organisms are suitable for Quadrat Sampling?

Suitable for plants that do not move around and are easy to find, but for field research the sampling strategy of choice will be systematic.

Define Percentage cover and frequency.

Percentage cover is an estimate of the area in a given frame size (quadrat) covered by the plant or animal in question, Percentage frequency is the number of occurrences divided by the number of possible occurrences.

What is a Line transect?

Tape measure laid out perpendicular to the gradient - only those touching tape counted.

What is a Belt transect?

Band (0.5 to 1 m) laid out perpendicular to the gradient all those - within area.

What are three main methods of analyzing populations of creatures that are sessile/do not move?

Frequency Percentage, Population Density, Percentage Cover

What is frequency?

Number of times a species is encountered.

What is coverage?

The proportion of ground that is covered by a species.

Drought Average rainfall Above average rainfall Using the Predator-Prey System Simulation what are the figures for these measurements.

A = 60 B = 14 C = 7

the Lincoln index

Population size estimate = 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.

Explain the Capture/Mark/Release/Recapture process.

1. Capture as many individuals as possible in the area occupied by the animal population, using netting, trapping or careful searching. 2. Mark each individual, without making them more visible to predators. 3. Release all the marked individuals and allow them to settle back into their habitat. 4. Recapture as many individuals as possible and count how many are marked and how many are unmarked.

What are assumptions of the Lincoln index

1. The population of organisms must be closed, with no immigration or emigration. 2. The time between samples must be very small compared to the life span of the organism being sampled. 3. The marked organisms must mix completely with the rest of the population during the time between the two samples.

What is a niche?

The role or job of a species in an ecosystem.

What is a habitat?

Place where an organism or population of organisms live.

What concept can be included when considering concept of habitat in a local ecosystem.

A description of the habitat of a species can include both geographical and physical locations, as well as the type of ecosystem required to meet all environmental conditions needed for survival.

What is an ecological niche?

The particular set of abiotic and biotic conditions and resources upon which an organism or a population depends.

Explain the niche concept using two examples.

Studies of the distribution of organisms and of interactions between organisms show that there are many different ways of existing in an ecosystem and how an organism makes a living

Define carrying capacity.

Maximum size of a population determined by competition for limited resources.

What is carrying capacity

The average population density or population size of a species below which its numbers tend to increase and above which its numbers tend to decrease because of shortages of resources

What curves can growth follow and why?

A J-curve (exponential growth) versus S-shaped (When density-dependent limiting factors start to operate)

Differentiate the population growth J and S curves.

J-shaped has no limiting factors

What regulates population size?

Density-dependent factors and negative feedback mechanisms.

What happens in an ideal environment?

Populations grow at an exponential rate

What factors increase population growth?

Includes effects of elimination of natural predators, technological advances, and degradation of the environment

Estimate the carrying capacity of an environment for a given species..

It is possible to estimate the carrying capacity of an environment for a given species

What should be considered when naming classification of organisms.

The first name is the genus, the second name is the species; species in the same genus have similar traits.

What tools do Taxonomists use to identify an organism?

Dichotomous keys, comparison of specimens, and DNA surveys.

What does identification mean?

Determining the species of an individual organism.

What are 2 descriptors used to make an adjusted to improve the accuracy of a classification system.

• is that generic terms such as Big or small are not useful. 2. comparative, quantitative descriptors and simple identification of the presence or absence of external features are most useful in keys.

In steady-state ecosystem, is sustainability is a natural property, so describe this process.

Inputs are balanced by outputs

What do tipping points lead to in ecosystem stability?

Tipping points lead to the collapse of the original ecosystem and development of a new equilibrium.

planetary boundaries model

Changes to biosphere integrity have passed a critical threshold

How do you avoid critical tipping points to species?

Protecting the integrity of ecosystems because Protecting ecosystems ensures the preservation of the niche requirements essential for the ongoing survival of a species.

What do keystone species do?

Have a disproportionate impact on community structure and the risk of ecosystem collapse if they are removed.

Define and name 2 ecosystem community drivers

Controlling mussel populations(purple sea stars) on the North Pacific coast that would otherwise overwhelm the ecosystem and feeding on shrubs and trees, and thus maintaining savannah Grasslands(elephants)

What is the fundamental niche of a species?

Describes the range of conditions and resources in which a species could survive and reproduce if there were no limiting factors.

What is the realized niche of a species?

The actual mode of existence, which results from its adaptations and competition with other species.

Describe K-strategists.

Thrive in stable communities by producing few offspring that have a high chance of survival.

Describe R-strategists.

Colonize new habitats rapidly and make opportunistic use of short-lived resources by producing many offspring with more limited provision for the individual’s survival.

Taxonomy's difficulty.

The traditional hierarchy of kingdom, phylum, class, order, family, genus and species does not always correspond with patterns of divergence generated by evolution.

How have organism have been classified?

Organisms have been classified on the basis of their morphology, but this can lead to errors; similarities in observable characteristics do not always mean that organisms share a recent common ancestor.

Define Phenology

Phenology is defined as the study of the timing of recurring biological events, the causes of their timing with regard to biotic and abiotic forces, and the interrelation among phases of the same or different species (Leith 1974).

Explain how do humans impact cycles?

Human impacts are contributing to climate change, which lead to a disruption in these cycles.