Ch 35 Population/ Community
Ecology
35.1 Population Density
Population density is the number of individuals of a particular species per unit area or volume.
Examples: 35 alligators per square km of a swamp
1,000,456 bacteria per cm2 of an agar plate
120 earthworms m2 of soil
Population density problems
On rare occasions you can count all the individuals ina population, such as the number of beech trees in aforest measuring 50 square kilometers (km2). Population density = Individuals = 1000 trees = 20 trees
Unit area 50 km2 km2
Population density is a helpful measurement for comparing populations in different locations.
Population DispersionPopulation Dispersion
35.2 There are limits to a population’s growth
Exponential growth: growth of a population that multiplies by constant factor
Limiting factor:condition that restricts a population’s growth, such as space, disease and food availability.
Carrying capacity: number of organisms in a population that an environment can maintain.
Exponential Growth Figure 35-5
This table shows how many bacteria are in a population that doubles every 20 minutes. The graph is another way to show the same data.
CARRYING CAPACITY
Figure 35-6Before the early 1900s, hunting kept this population of fur seals below the carrying capacity of the environment. Then, after hunting was reduced, the population grew almost exponentially for two decades. The population began to level off as it reached the carrying capacity.
Figure 35-6
Changes in Population Changes in Population SizeSize Growth factors (increase in pop.) Growth factors (increase in pop.)
Immigration: individuals moving into a population
Births Shrinking factors (decrease in pop.)Shrinking factors (decrease in pop.)
Emigration: individuals moving out of a population
Deaths
Growth factors (increase in pop.) Growth factors (increase in pop.) Immigration: individuals moving into a
population Births
Shrinking factors (decrease in pop.)Shrinking factors (decrease in pop.) Emigration: individuals moving out of a
population Deaths
Exponential Growth= J Exponential Growth= J curve curve
Early phase of growthEarly phase of growth High availability of High availability of
resourcesresources Little competitionLittle competition Little predationLittle predation
Early phase of growthEarly phase of growth High availability of High availability of
resourcesresources Little competitionLittle competition Little predationLittle predation
Logistic Growth= S curveLogistic Growth= S curverepresent Carrying capacityrepresent Carrying capacity
Limits on growth Limits on growth appearappear Competition for Competition for
resourcesresources Predation Predation ParasitismParasitism IllnessIllness
Limits on growth Limits on growth appearappear Competition for Competition for
resourcesresources Predation Predation ParasitismParasitism IllnessIllness
35.3 Human Population Growth
The human population is now growing at a rate of about: 3 people/second or 260 thousand/day or 1.8 million per week or 93 million/year
Earth’s Carrying Capacityabout 50 Billion
Human Population Human Population GrowthGrowth
Are humans in exponential or logistic growth?Are humans in exponential or logistic growth?
An elephant, cannot survive without other
organisms. elephant herd of elephants (population) an elephant’s community An elephant’s community = gazelles, giraffes, birds, ants, beetles, fungi,
bacteria, grasses, trees
Members of a population compete for limited resources in the environment.
-Competition within a single species limits the growth of the population.
Interspecific competition: when two or more species rely on the same limited resource
(competition between 2 different species) example:during times of drought in an African savanna community, grasses may
be in short supply, and competition becomes intense.
35.4 Interactions in Communities Competition Between Species
Competitive ExclusionCompetitive
exclusion: One species succeeding over another, when the growth of both species is limited by the same resource.
Figure 35-14Two similar species may each thrive in separate locations, but one may exclude the other when they are placed together. The results of an experiment with two Paramecium species demonstrate this principle of competitive exclusion.
NICHE
Niche: a unique living arrangement of
an organism defined by its living
place (habitat), its food sources, the
time of day it is most active, and
other factors The local loss of a species is likely to occur if 2 species have niches that are
very similar
niches are rarely identical.
Example: one lizard in a tropical forest feeds on insects in low shrubs, while
a similar lizard may eat insects high in the trees.
PredationPredation: an interaction in which one organism eats
another.
The lion attacks and eats an injured zebra or an
egret catches and eats a fish.
Predator: the organism that kills/ eats the prey.
Prey: the organism that gets eaten.
eating and avoiding being eaten are important to
survival,
many effective adaptations have evolved in both
predators and prey.
Predator/ Prey
Predator Adaptations
fast and agile camouflage teaming up in packs acute senses claws, teeth, fangs, and stingers
Ex. Rattlesnakes locate their prey with heat-sensing organs located between each eye and nostril.
Prey Adaptations
retreat to safe locations
flee from predators
camouflage to hide
"warning coloration" is a caution to
predators.
mimicry -look like organisms that are
poisonus or dangerous.
Plants have poisonous chemicals and
structures such as spines and thorns.
Warning Coloration
Monarch w/ warning coloration
Viceroy Butterfly- mimics Monarch
Symbiotic Relationships Symbiotic relationship is a close interaction between
species in which one of the species lives in or on the
other.
3 main types of symbiotic relationships: parasitism,
mutualism, and commensalism.
1.) Parasitism is a relationship in which the parasite
obtains its food at the expense of the host.
Usually the parasite is smaller than the host. (blood-
sucking mosquitoes and tapeworms)
Ticks
Mutualism: both organisms benefit from the symbiotic relationship.
Your large intestine is inhabited by millions of
bacteria.
The bacteria benefit by having a warm, moist
home and food.
Intestinal bacteria produce vitamin K. Vitamin
K is essential for blood clotting.
Both you and the bacteria benefit from this
relationship.
Mutualism
Pair of Coleman Shrimp on fire urchin
Manta Ray with Remoras
Commensalism is a relationship in which one organism benefits, while the other organism is neither harmed nor helped significantly.
Example:A spider crab may place seaweed on its back. The crab
benefits by being camouflaged from its predators. The seaweed is not affected.
commensalism in nature is rare, since most interactions harm one species (parasitism) or help both species (mutualism) to some degree.
Commensalism
35.5 Disturbances are common in communities
Ecological SuccessionEcological succession. Series of changes in the species of a community, often followed by a disturbance.
Primary Succession- process by which a community arises in a lifeless area that has no soil
barren ground lichen/mosses grass shrubs pine trees hardwood trees
Examples: Forest devastated by a fire, or volcano new islands created by erupting volcanoes bare rock left behind a retreating glacier.
Primary SuccessionPrimary Succession The establishment and development of an
ecosystem in an area that was previously uninhabited
The establishment and development of an ecosystem in an area that was previously uninhabited
Lichensand
mosses
GrassesAnd
small shrubs
Large shrubs and small trees
Large trees
Primary Succession
Surtsey: A Case StudySurtsey: A Case Study The island of Surtsey formed by volcanic
eruption off of the coast of Iceland during the period from 1963 - 1967
Surtsey – Post EruptionSurtsey – Post Eruption
Surtsey TodaySurtsey Today
Secondary Succession Secondary succession when a disturbance
damages an existing community but leaves the soil intact
Grasses shrubs trees similar to the original forest.
Example: when a forested area is cleared for farming and then
abandoned.
Secondary SuccessionSecondary Succession The recovery of a damaged ecosystem in
an area where the soil was left intact
The recovery of a damaged ecosystem in an area where the soil was left intact
FireweedFireweed Sequoia seedlingSequoia seedling
Case Study: Yellowstone National Case Study: Yellowstone National ParkPark1988 – Devastating forest fires burn much of
Yellowstone National Park.
Photo: National Parks Service
YellowstoYellowstone ne National National ParkPark1988 – Park mapshowing areas
(1.6 million acres)burned by theseries of fires.
Yellowstone National ParkYellowstone National Park1988 fires – The immediate aftermath.
Photo: National Parks Service
Yellowstone Yellowstone National National ParkPark
One year after the fires
Note the appearance of fireweed
Photo: National Parks Service
Yellowstone National Yellowstone National ParkPark
Ten years after the fires (1998)
Photo: National Parks Service
Yellowstone National Yellowstone National ParkPark
Twenty years after the fires (2008)
Case Study - ChernobylCase Study - Chernobyl
In April, 1986, a nuclear power plant in the former USSR experienced a core meltdown and a catastrophic release of radioactivity into the environment.
ChernobylChernobyl
Surrounding towns and villages had to be immediately, permanently abandoned.
Chernobyl – Twenty Years Chernobyl – Twenty Years LaterLater
Chernobyl – Twenty Years Chernobyl – Twenty Years LaterLater
Pripyat town square.
Chernobyl – Twenty Years Chernobyl – Twenty Years LaterLater
Pripyat Soccer Stadium opened in 1986.
Chernobyl – Twenty Years Chernobyl – Twenty Years LaterLater
A local highway.
Secondary succession: trees are colonizing uncultivated fields and meadows
Human Activities and Species Diversity
humans have had the greatest impact on communities worldwide.
60 % Earth's land is used by humans, mostly as cropland or rangeland.
Human disturbances have a negative effect on species diversity
Clearing the Land for lumber land for farming Land for building. paved over or eventually recolonized by weeds and
shrubs, as in abandoned city lots.
Invasive SpeciesInvasive Species
Courtesy www.lab-initio.com
Invasive SpeciesInvasive Species Introduced speciesIntroduced species: any organism that was brought to an ecosystem as the result of human actions
Invasive speciesInvasive species: A species that takes advantage of an unoccupied niche, or that successfully out-competes native species
Introduced speciesIntroduced species: any organism that was brought to an ecosystem as the result of human actions
Invasive speciesInvasive species: A species that takes advantage of an unoccupied niche, or that successfully out-competes native species
Kudzu:Kudzu: an invasive vinean invasive vine
Introduced Species Introduced species are organisms that
humans move from the species' native locations to new geographic areas, either intentionally or accidentally (exotic species).
Kudzu, a Japanese plant planted widely in the American South (1930s) to help control erosion. especially along irrigation canals. But kudzu soon grew out of control, taking over vast expanses of landscape.
Some introduced species gain a foothold and may disrupt their new community.
Some introduced species prey on native species or outcompete native species
Invasive species
Invasive species are "alien” species whose introduction does or is likely to cause economic or environmental harm or harm to human health"
U.S. Invasive Aquatic Plants U.S. Invasive Aquatic Plants
Partial list:Brazilian Waterweed Caulerpa, Mediterranean Clone Common Reed Eurasian Watermilfoil Didymo Giant Reed Giant Salvinia Hydrilla Melaleuca Purple Loosestrife Water Chestnut Water Hyacinth Water Lettuce Water Spinach
Partial list:Brazilian Waterweed Caulerpa, Mediterranean Clone Common Reed Eurasian Watermilfoil Didymo Giant Reed Giant Salvinia Hydrilla Melaleuca Purple Loosestrife Water Chestnut Water Hyacinth Water Lettuce Water Spinach
HydrillaHydrilla
U.S. Invasive Aquatic U.S. Invasive Aquatic AnimalsAnimals
Partial list:Partial list:Alewife New Zealand Mud Snail Northern Snakehead Asian Carps Nutria Asian Swamp Eel Quagga Mussel Bullfrog Round Goby Chinese Mitten Crab Rusty Crayfish Eurasian Ruffe Sea Lamprey European Green Crab Sea Squirt Flathead Catfish Spiny Water Flea Lionfish Veined Rapa Whelk
Zebra Mussel
Partial list:Partial list:Alewife New Zealand Mud Snail Northern Snakehead Asian Carps Nutria Asian Swamp Eel Quagga Mussel Bullfrog Round Goby Chinese Mitten Crab Rusty Crayfish Eurasian Ruffe Sea Lamprey European Green Crab Sea Squirt Flathead Catfish Spiny Water Flea Lionfish Veined Rapa Whelk
Zebra Mussel
Zebra MusselZebra Mussel
U.S. Invasive InvertebratesU.S. Invasive InvertebratesPartial list:Partial list:Africanized Honeybee Asian Citrus Psyllid Asian Long-Horned Beetle Asian Tiger Mosquito Cactus Moth Emerald Ash Borer European Gypsy Moth European Spruce Bark BeetleFormosan Subterranean Termite Giant African Snail Glassy-Winged Sharpshooter Hemlock Woolly Adelgid Light Brown Apple Moth Mediterranean Fruit Fly Mexican Fruit Fly Pink Hibiscus Mealybug Red Imported Fire Ant Russian Wheat Aphid Silverleaf Whitefly Sirex Woodwasp Soybean Cyst Nematode
Partial list:Partial list:Africanized Honeybee Asian Citrus Psyllid Asian Long-Horned Beetle Asian Tiger Mosquito Cactus Moth Emerald Ash Borer European Gypsy Moth European Spruce Bark BeetleFormosan Subterranean Termite Giant African Snail Glassy-Winged Sharpshooter Hemlock Woolly Adelgid Light Brown Apple Moth Mediterranean Fruit Fly Mexican Fruit Fly Pink Hibiscus Mealybug Red Imported Fire Ant Russian Wheat Aphid Silverleaf Whitefly Sirex Woodwasp Soybean Cyst Nematode
U.S. Invasive VertebratesU.S. Invasive VertebratesPartial list:Partial list: At Risk of Widespread At Risk of Widespread Brown Tree Snake IntrusionIntrusionCane Toad Constrictor snakesEuropean Starling Boiga snakesWild Boar Gambian pouch ratHouse SparrowNutria
Partial list:Partial list: At Risk of Widespread At Risk of Widespread Brown Tree Snake IntrusionIntrusionCane Toad Constrictor snakesEuropean Starling Boiga snakesWild Boar Gambian pouch ratHouse SparrowNutria
European StarlingEuropean Starling
Cane ToadCane Toad
U.S. Invasive PlantsU.S. Invasive Plants
Yellow Star ThistleYellow Star Thistle
U.S. Invasive MicrobesU.S. Invasive MicrobesAnimal Pathogens Animal Pathogens Avian Influenza Exotic Newcastle Disease Fowlpox Viral Hemorrhagic Septicemia West Nile Virus Whirling Disease Plant PathogensPlant PathogensCitrus Canker Citrus Greening Plum Pox Southern Bacterial Wilt Soybean Rust Sudden Oak Death
Animal Pathogens Animal Pathogens Avian Influenza Exotic Newcastle Disease Fowlpox Viral Hemorrhagic Septicemia West Nile Virus Whirling Disease Plant PathogensPlant PathogensCitrus Canker Citrus Greening Plum Pox Southern Bacterial Wilt Soybean Rust Sudden Oak Death
West Nile VirusWest Nile Virus
Citrus CankerCitrus Canker
Kudzu vines
Zebra Mussels clogging pipes
Zebra mussels clogging pipe
35.5 DISTURBANCES
DefinitionsDefinitions Bioaccumulation: Bioaccumulation: is the process by
which substances not readily broken down or excreted can build up and be stored in living tissue (usually in fatty tissue.)
BiomagnificationBiomagnification: : is the process by which substances become more concentrated in the bodies of consumers as one moves up the food chain (trophic levels).
Bioaccumulation: Bioaccumulation: is the process by which substances not readily broken down or excreted can build up and be stored in living tissue (usually in fatty tissue.)
BiomagnificationBiomagnification: : is the process by which substances become more concentrated in the bodies of consumers as one moves up the food chain (trophic levels).
Case Case Study: Study: PCBsPCBs
PCBs, or polychlorinated biphenyls, are a group of man-made chemicals.
Introduced in 1929 and widely used in electrical transformers, cosmetics, varnishes, inks, carbonless copy paper, pesticides and for general weatherproofing and fire-resistant coatings to wood and plastic.
The federal government banned the production of PCBs in 1976
PCBs can effect the immune system, fertility, child development and possibly increase the risk of certain cancers
PCBs, or polychlorinated biphenyls, are a group of man-made chemicals.
Introduced in 1929 and widely used in electrical transformers, cosmetics, varnishes, inks, carbonless copy paper, pesticides and for general weatherproofing and fire-resistant coatings to wood and plastic.
The federal government banned the production of PCBs in 1976
PCBs can effect the immune system, fertility, child development and possibly increase the risk of certain cancers
Case Study:Case Study:DDTDDT
DDTDDT is a pesticide that was widely used until being banned in the U.S. in 1972
DDTDDT accumulates in living tissue, particularly in fat tissue
High concentrations in some bird species caused failure of eggs by thinning the shells
DDTDDT is a pesticide that was widely used until being banned in the U.S. in 1972
DDTDDT accumulates in living tissue, particularly in fat tissue
High concentrations in some bird species caused failure of eggs by thinning the shells
U.S. Department of the Interior, U.S. Geological Survey, Center for Coastal GeologyThis page is: http://sofia.usgs.gov/sfrsf/rooms/mercury/achilles_heel/cause.html
Case Study:Case Study:Methyl MercuryMethyl Mercury
Mercury Health Effects