Bio 3 Exam 4

What is ecology?

Study of interactions that living things have with each other and with their environment

Different levels of study

Individuals, population, community, ecosystem

Individuals

study of individual organisms within an environment

Population

all members of a single species living in the same geographic area at the same time

Community

Populations of all species that interact with one another in the same geographic area

Ecosystem

Community of organisms and the physical environment with which they interact

Demography

the study of factors that determine the size and structure of population through time

Four factors that determine the actual size of a population

Natality (birth rate)

Mortality (death rate)

Immigration (migrate into a population)

Emigration (migrate out of an area)

Fecunidty

The number of female offspring produced by each female in the population

Why is Fecundity important?

Actual reproductive rate of the population

Exponential growth

When the growth rate is unaffected by population size, the population’s size increases at a rate proportional to its current size, J-curve.

Logistic growth

the density-dependent decrease in growth rate as population size reaches the carrying capacity. S- shaped curve

Carry capacity (K)

the maximum population size of a certain species that a given habitat can support

Environmental resistance

forces of the environment that act to limit population growth

(competition for resources, predation, disease

Density dependent

When the density of the population becomes limited by factors that limit population growth

K-selected species

One whose population sizes tend to be limited by carrying capacity (density dependent)

r-selected species

One whose population size is limited by reproductive rate (density independent)

R- selected species

Unstable environment

Small organism size

Little energy is used to produce each offspring

Many offspring produced

early maturity

Short life expectancy

Single reproduction in lifetime

K-selected species

Stable environment

Large organism size

Large amount of energy used to produce each offspring

Few offspring produced

Late maturity (long parental care)

Long life expectancy

Multiple reproductions in lifetime

Competition

occurs when individuals use the same resources

Predation and parasitism

Occurs when one organism eats or absorbs nutrients from another

Mutualism

occurs when two species interact in a way that confers fitness benefits to both

Commensalism

Occurs when one species benefits but the other species is unaffected

Intraspecific competition

completion among members of the same species (resources,space,sunlight,food,mates)

Interspecific competition

Competition among individuals of different species for the same limited resources

Ecological niche

An organism’s place or role within a community

(space it requires, food it consumes, reproductive requirements)

Competitive exclusion principle

Two species cannot occupy the same ecological niche in the same area, because one species will always out compete the other

Fundamental niche

the full range of environmental conditions and resources an organism can possibly occupy and use in the absence of competitors (western gray squirrels can live urban area)

Realize niche

The part of the fundamental niche that an organism occupies as a result of competitors in the habitat (fox squirrels outcome gray squirrels in urban areas)

Resources paritioning

When species evolve to occupy different ecological niches to reduce the amount of competition between species

Leads to coexistence (different bill lengths in shorebirds allow different species to specialize in different prey types)

Character displacement

occurs when competition between species

parasitism

a non-mutual symbiotic relationship, where one species (the parasite) benefits at the expense of the other (the host)

Predator and prey relationships

Predator and prey populations are often linked in a dynamic relationship of population increase and decreases

Why are predators important

They control prey population

Keystone species

a species whose absence in community would bring about significant change in that community

What is an ecosystem engineers

Ecosystem engineers are organisms that alter the landscape and transform the community structure.

(key stone species

Elephants eat lots of vegetation and transport seeds in dung

Beavers create dams that flood landscapes

bison graze and trample ground which increase biodiversity of grasslands)

Coevolutionary arms race

a repeating cycle of reciprocal adaptation between predators and prey

example of coevolutionary arms race

Camouflage: blending into the background

Schooling: safety in numbers

Weaponry: fighting back

Coevolution

Interdependent evolution of two or more species

Biodiversity

the variety of plants and animals, or other living things, in a particular area or region

What are the three levels of biodiversity

Genetic diversity, Species diversity, Ecosystem diversity

Genetic diversity

genetic variation among individuals of the same species (adaptive potential

Disease resistance

Antibiotic resistance)

Species diversity

the variety of species within an ecosystem

Benefits of species diversity

Health of an ecosystem diverse + they have greater adaptive potential

Potential to benefit humans for medications

Food

products

Food chain

the linear transfer of energy between organisms in an ecosystem from producers to consumers (phytoplankton > krill > whale)

Food web

the interconnection of all the food chains within a particular ecosystem

Trophic levels

Primary producers

Primary consumers

Secondary consumers

Tertiary consumers

Primary producers

autotrophs (plants) that convert solar energy to chemical energy

Primary consumer

herbivores are animals that eat plants

Secondary consumers

Carnivores are animals that eat herbivores

Tertiary consumer

carnivores that eat other carnivores

How much biomass is transferred from one trophic to another?

10% is transferred

Biomagification

Toxic substances become increasingly concentrated within living things as they move up each level (DDT, thinned bird eggs)

Trophic cascade

occurs when predators limit the density of prey leading to indirect impacts on the lower trophic levels within can shape the entire ecosystem

Ecosystem diversity

Variation of the types of ecosystems in a given area

Many ecosystems are under threat in

Developing areas

Ecosystem services

All the processes through which natural ecosystems benefit human life.

(provide water, food and building material

Oxygen production and nutrient cycling

Medicinal benefits derived from plants

pollinators

Erosion control

water filtration

Decomposition of organism material

Recreation and cultural services)

Humans are currently experiencing exponential growth

true

Trophic cascade before removal of wolves

mix of large and small predators

diverse plant community

Diverse song bird community

fewer large herbivores

Trophic Cascade After removal of Wolves

Large predators absent; small predators dominate

simplified plant community

Lower songbird diversity

numerous large herbivores

Extrinsic value

The value to humans, ecosystem services

Intrinsic value

the worth of an entity independent from external circumstances or its value to human

how many mass extinctions events have occured in the past

Five

Whats causing the current mass extinction event

Humans

What mass extinction event resulted in the loss of dinosaurs?

Cretaceous

what mass extinction event resulted in the loss of most species

Permian

Biodiversity hotspots requirements

At least 1500 endemic plant species

70% of loss of original habitat

36 areas around the world

Endemic

Species found only in a distinct geographic area

Human impacts on biodiversity

Habitat destruction and loss (destroying natural habitats)

Fragmentation (separation of ecosystems into smaller ones)

Habitat degradation (invasive, pollution)

What type of animals are under greatest threat of extinction

Wild animals because of humans

The greatest threat to biodiversity is

Habitat destruction and loss (mostly by agriculture)

Deforestation

The clearing of forests and the conversion of the land for non-forests use

How is fragmentation associated with urbanization

Fragments of habitat may not be large or connect enough to support species that need a large territory where they can find mates and food

Aquatic species habitats have been fragmented by damns and water diversions

The loss of fragmentation of habitats makes it difficult for migratory species to find places to rest and feed along their migration routes

Eutrophication

excessive richness of nutrients in a lake or other body of water, frequently due to runoff from the land, which causes a dense growth of algae and bacteria resulting in the death of animal life from lack of oxygen

Hypoxia

The depletion of oxygen in the water often resulting in dead zones

Overfishing

Overexploitation of fish stocks in an unsustainable manner

30% of all commercial fish stocks are overfished

Factors that lead to overfishing

International waters are unregulated resulting in ocean access fisheries.

Poor fisheries management (fish caught by multiple countries, making data collection difficult to impossible)

Illegal fishing (catches are unreported)

Subsidized fishing fleets result in 2 times more fleets than necessary

Fishing down the food web

Process by which fisheries deplete large predatory fish then begin to catch smaller and smaller species

Bycatch

a fish or other species that is caught unintentionally

Aquaculture

Farming of aquatic organisms including fish, molluscs, crabs and algae

Marine plastics

are consumed by a variety of marine species

Shark finning

The removal of sharks fins often while the shark is still alive

Invasive species

a species that is non-native to an ecosystem and has caused or is likely to cause economic or environmental harm

Characteristics of successful invasive species

fast growth

rapid reproduction

tolerance to wide range of environmental conditions

high dispersal ability

lack of natural predators

Negative impacts of an invasive species

change of entire habitat

alter ecosystem dynamics

loss of genetic diversity

spread of diseases

Invasive species introductions

intentional introductions (pigs)

Unintentional introductions (rats on ships)

Horticulture (crop plants that later escape)

Ballast water (small marine organisms)

Pet trade (lion fish)

climate change

97% of scientist agree that climate trends over the last century are due to humans

4 main green house gases

Carbon dioxide

methane

Nitrous oxide

fluorinated gases

green house gases

reflect infrared radiation back to earth’s surface

Sources of greenhouse gases

carbon dioxide (burning of fossil fuels, solid waste, trees and wood)

Menthane (decomposition in landfills, production of coal, natural gas and oil, agriculture)

Nitrous oxide (agriculture and fertilizers, combustion of fossil fuels)

Fluoridated gases (aerosols)

since 1990 what green house gas has increased

carbon dioxide

U.S., Europe and Asia account for about

88% of total global emission

Carbon sequestration

the removal and storage of atmospheric carbon dioxide in oceans, terrestrial environments, or geologic formations.

Carbon sink

Anything that absorbs more carbon dioxide than it releases

Conservation Biology

Science developed to address the loss of biological diversity and focuses on protecting species, their habitats and ecosystems

Two primary goals of conservation Biology

Evaluate human impacts on biodiversity

Develop practical approaches to prevent the extinction of species

First legislation for converation of species was

the sea birds preservation act of 1869

National environmental policy act

requires all federal agencies to prepare environmental assessments and environmental impact statements to determine negative impacts associated with proposed projects.

California Environmental Quality Act

Requires all states and local agencies to analyze and disclose all potential environmental impacts of proposed projects, and adopt measures to mitigate any negative impacts to the environment