Semester 1: Unit 3ECOLOGY
• Ecology- scientific study of interactions among & between organisms & their physical environment.
3.1- What is Ecology?
• Ecology studies levels of organization:
*Specie- Individual organism
*Population- group of the same type of individuals that live in the same area
*Community- groups of different populations living together in a defined area
*Ecosystem- all the organisms that live together in a place with their physical environment
*Biome- a group of ecosystems that share similar climates & typical organisms
*Biosphere- entire planet
3.1- What is Ecology?
•biotic factors- biological influences on organisms (living factors)
• Examples of biological influences on a bullfrog- algae it eats as a tadpole, herons that eat bullfrogs, & other species competing for food or space.
3.1- What is Ecology?
• Abiotic factors- physical components of an ecosystem (nonliving factors)
• a bullfrog could be affected by abiotic factors such as water availability, temperature, & humidity.
3.1- What is Ecology?
• abiotic & biotic factors- not always clear
• Ex: pond muck contains nonliving particles, mold, & decomposing plant material that is food for bacteria & fungi
4.1- Climate
• Weather - day-to-day conditions of Earth’s atmosphere
• Climate- year-after-year patterns of temperature & precipitation.
• main force in climate= solar energy from sun• Some energy absorbed & converted into heat
• Some heat is trapped in the biosphere & determines average temperature
4.1- Climate
4.1- Climate• Earth’s temp controlled by 3 atmospheric gases- CO2,
methane, & water vapor
• “greenhouse gases”- allow light to enter but trap heat- the greenhouse effect
• Greenhouse gas concentrations rise, more heat trapped= Earth warms.
• Without greenhouse effect, Earth would be 30°C cooler than it is today.
4.1- Climate
4.2- Niches & Community Interactions
• Each species has its own tolerance- ability to survive & reproduce under a range of environmental circumstances.
• Cannot survive past upper & lower limits
4.2- Niches & Community Interactions
• Habitat- place an organism lives. (address)• Niche- conditions in which a species lives &
how it obtains what it needs to survive & reproduce. (job)
• resource - necessity of life- water, nutrients, light, food, mates, space
• Competition- organisms try to use the same limited resource in same place at same time
• competitive exclusion principle- no 2 species can occupy exactly the same niche in the same habitat at the same time
4.2- Niches & Community Interactions
Showing different species
in different niches in
same habitat
Competition:
winner? Loser?
4.2- Niches & Community Interactions• Predation- one animal (predator) captures &
feeds on another (prey)
• symbiosis- relationship in which 2 species live closely together
3 types of symbiotic relationships:• mutualism- both species benefit• parasitism- 1 organism lives in/on another &
harms it• commensalism- 1 organism benefits & other is
not helped or harmed
4.3- Succession
• Ecological succession- series of predictable changes that occurs in a community over time
1-primary succession- begins in areas with no soil or life (ex- volcanic explosion)
• pioneer species- 1st to colonize barren areas
4.3- Succession2-secondary succession- begins where soil remains
• rebuilds faster than primaryex-wildfire, hurricane, natural disturbance, or
human activities- logging & farming.
4.4- Biomes• Biomes- consist of
abiotic & biotic factors
• seasonal patterns
of temp & precipitation
in a- climate diagram
• Temp- line graph
• Precipitation- bar graph
5.1- How Populations GrowExponential Growth:
• Ideal conditions & unlimited resources, population grows exponentially
• the larger a population, faster it grows
• on a graph over time, a J-shaped curve
5.1- How Populations Grow
Logistic Growth:
• a population’s growth slows & then stops, following exponential growth.
• Natural populations do not grow long exponentially; something stops growth
• On a graph, curve has an S-shape
5.1- How Populations Grow• Carrying capacity- maximum # of individuals that a
particular environment can support.
• Where dotted line intersects the y-axis = carrying capacity.
5.2- Limits to Growth
• limiting factor- factor that controls the growth of a population
1. Density-dependent limiting factors -operate strongly when population density is large.
• D-D L F: competition, predation, herbivory, parasitism, disease, stress from overcrowding
Competition:
• populations become crowded, individuals compete-food, water, space, sunlight, etc.
• lower birthrates, increased death rates
5.2- Limits to Growth
Predation:
predator population affects prey population & vice-versa
Herbivore Effects:
To plants, herbivores are predators
5.2- Limits to Growth
Parasitism and Disease:
• Parasites & disease-causing organisms feed & harm hosts- weaken, cause disease, or death
• more dense host population, easier to spread
Stress From Overcrowding:
• species fight if overcrowded; increase stress & weaken body’s ability to resist disease
• Females neglect, kill, or eat own offspring
• decrease births, increase deaths, & increase emigration
5.2- Limits to Growth2- Density-Independent limiting factors- affect all
populations regardless of size & density
• D-I L F include: Unusual weather- hurricanes, droughts, floods, & natural disasters- wildfires
6.1- A Changing Landscape
• Sustainable development- provides for human needs & preserves ecosystems that produce natural resources.
• Goods- items that can be bought & sold
• Services- processes or actions that produce goods.
• ecosystem goods & services- produced by ecosystems that benefit human economy.
• Healthy ecosystems provide goods & services naturally & free of charge: air, water
6.2 Using Resources Wisely
Biological magnification- a
pollutant is picked up by
an organism & is not broken
down or eliminated from
its body.
• pollutant collects in body tissues &
build as it moves up
trophic levels
6.3 Biodiversity
• Biodiversity- total of all the genetically based variation in all organisms in biosphere.
• Ecosystem diversity- variety of habitats, communities, & ecological processes in the biosphere
• species diversity- number of different species in the biosphere or particular area
• Genetic diversity- sum total of all different forms of genetic information carried by a particular species, or all organisms on Earth.
6.3 Biodiversity• Humans reduce biodiversity by:
*altering natural habitats *hunting *introducing invasive/exotic species *releasing pollution into food webs*contributing to climate change
• To conserve biodiversity, we must protect species, preserve habitats & ecosystems
• ecological hot spot- place where large numbers of species & habitats are in immediate danger of extinction.
6.3 Biodiversity
• Development splits ecosystems into pieces- habitat fragmentation- leaving habitat “islands” - patch of habitat surrounded by a different habitat.
6.4 Meeting Ecological Challenges• ecological footprint- total area of functioning land &
water ecosystems needed to provide the resources an individual or population uses & to absorb the wastes that it generates.
6.4 Meeting Ecological Challenges
• Ecology can guide humans toward a sustainable future & have a positive impact on the global environment by:
(1) recognizing a problem in the environment
(2) researching the problem to determine its cause
(3) using scientific understanding to change our behavior