2.1 Individuals, Population, Communities, and Ecosystems

Biosphere

an ecological system composed of individuals, populations, communities, and ecosystems, it represents the parts of the earth where life exists

Individual organism

a member of a species

Population

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

Community

a collection of interacting populations within the ecoysytem

Habitat

the location in which a community, species, population, or organism lives

Ecosystem

open systems in which both energy and matter can enter and exit

Binomial name

first part: genus, second part: name of species

Classification of animals

Dichotomous Key

consists of a series of paired statements/clues that provide aa guide to identifying each entity

Factors that determine the distribution of populations can be..

abiotic or biotic

Abiotic factors

non-living physical factors

Biotic factors

living, biological factors

Niche

the particular abiotic and biotic conditions and resources to which an organism or population responds

Species interactions

Herbivory

consumption of plant species by an animal

Predation

consumption of one species (prey) by another

Parasitism

symbiotic relationship; one species is benefitted and the other is adversely affected

Mutualism

symbiotic relationship where both partners benefit

Disease

caused by pathogens like viruses, bacteria, or fungi

Competition

interaction between organisms trying to both get a resource

Sustainability is..

a natural property of ecosystems

Human activity can lead to…

tipping points in ecosystem stability

Keystones

a single species in an ecosystem that maintains the structure + function

Biosphere integrity

encompasses species and genetic diversity as well as ecosystem function

compromising biosphere integrity will lead to..

reduction in ecosystem services, cascading effects, loss of reslience

To avoid tipping points..

the loss of biosphere integrity needs to be reversed

Carrying capacity

the maximum size of a population, determined by competition for resources

Carrying capacity is affected by

human activity, and biotic/abiotic factors

Population size is regulated by

density dependent factors

Density dependent factors

limiting factors that tend to regulate population size around carrying capacity (eg. competition, predation, and disease)

Density independent factors

limiting factors that will have an affect on population regardless of the size and abundance (eg. natural disasters or human activity)

Population growth can be either

exponential or limited by carrying capacity

S Curve

J Curve

In reality…

combination of S and J

Human population

limiting factors have been eliminated

Eliminate limiting factors

Reduce natural predation, tech advancement, medical care, agriculture

Consequences for ecosystems

resource depletion, pollution, and habitat destruction

Human Carrying Capacity cannot be easily estimated due to

Broad/changing niches, tech advancements, mobility of resources, change in consumption patterns

Population abundance can be measured by

estimating, using random sampling, systematic sampling, or transect (stratified) sampling

Random sampling

each member of population has equal chance

Systematic sampling

study area includes an environmental gradient, transects used to systematically sample

Stratified sampling

proportionate number of observations taken from each part of population, divided into zones, samples from each zone

Random quadrant sampling for non motile organisms

population abundance, population density, percentage cover, and percentage frequency

For motile populations

capture-mark-release-recapture can be used

Capture-mark-release-recapture

capture organisms, mark, release back, recapture, and determine ratio of marked vs unmarked

Lincoln Index

(M x N) /R, m = number of individuals captured and marked, n = total number of individuals recaptured, r = marked indivdiuals recaptured