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