Threatened, Endangered and Extinct Species

Standard 4.7

How many species are on Earth?

Scientists identified about 1.75 millionCould be as many as 100 millionSpecies can appear and disappear

Extinction

An extinct species is one that no longer exists.

Extinction is a natural process.The rate of extinction is increasing due to

human activities such as pollution. Removing organisms will change

ecosystems.

Effects of Extinction

Causes a loss of animals that help cycle nutrients through the environment

Lose plants that provide food and oxygenLoss of organisms that could supply new

medications

Biodiversity

Biodiversity – refers to the great variety of organisms on Earth

Three major levels– Genetic– Species – Ecosystem

Biodiversity

Also involves genetic variation within a particular species

Human Examples– Physical Traits – hair

color, height, eye color and susceptibility to disease

Pennsylvania’s Biodiversity

More than 20,000 different species in PABesides animals other common organisms

in PA include:– Insects, plants, fungi and lichens

Scientists in PA are trying to maintain biodiversity by listing and monitoring as many species as possible.

Lichens

Pennsylvania’s Biodiversity

23%

47%

16%

3%

4% 7%

Plants/Algae

Insects

Fungi/Lichens

Vertebrates

Protists

Non-insect invertebrates

Interactions Among Organisms

Remember the food web – all organisms rely on other organisms

Predator-prey relationships help to keep an ecosystem in balance– An organism of one species (the predator) eats a living

organism of a different species (the prey)

Examples: polar bears eat fish, lions that eat zebras, robins that eat worms.

Examples Predator-Prey

Interactions Among Organisms

As the prey population increases, ecosystems can support more predators

As the prey population decreases, the lack of prey causes the predator population to decrease

This allows for a stable carrying capacityThis also allows the strongest and fittest

members of the community to survive

Other relationships

Symbiosis – organisms live closely together over a long period of time

Can be parasitic, mutualistic, or commensalistic

Other relationships

Parasitism – one species, the parasite, feeds on a second organism the host

Parasite harms the host by living in or on itExamples: ticks or mosquitoes that live off

of the hostParasitism promotes ecosystem stability by

preventing the populations of some organisms from becoming too large

Parasitism Example

Other relationships

Mutualism – both species involved in the symbiotic relationship benefit

Examples:– Bees and flowers – bees feed on flower nectar,

and spread flower pollen in the process– Lichens – are two organisms, alga and fungus

that grew together• The algae undergo photosynthesis and provide

food for the fungi and itself while the fungi gathers water and minerals to share with the algae

Mutualism Example

Other relationships

Commensalism – one organism benefits while the other is not affected

Example: Trees in the rain forest block sunlight from reaching the ground, therefore plants such as orchids establish roots high in tree branches, growing through the high canopy to reach sunlight– The orchid can receive moisture and nutrients

from the air and does not harm the tree

The Human Impact

When humans destroy habitats, kill off species or pollute the natural environment biodiversity often decreases

As a result ecosystems break down

Adaptations

Adaptation – special modification or characteristic that helps an organism better survive in its environment, and which typically develops over time or may be passed down from one generation to another

Adaptations can be structural (or physical), behavioral (or responsive)

Structural or Physical Adaptations

Examples: desert plants with thick, wax-coated leaves

Predator birds – bald eagles have keen eyesight and are capable of flying at great speeds in order to catch prey

Behavioral or Response Adaptations

Example: An animal that cannot regulate its internal temperature, such as lizards or snakes, sit in the sun on cool days to warm itself– Retreats to its burrow

on hot days to cool itself

Structural Adaptations

Structural adaptations - are physical characteristics that help an organism survive in its environment

They help animals to perform basic tasks, such as moving or eating

Examples – Meat-eating animals have sharp incisors for killing prey

Plant eating animals have large, flat teeth that allow them to grind plants into pieces that are easily swallowed

Structural Adaptation Examples

Animals in deserts thousands of miles apart have the same types of adaptations

Plants that grow in the deep shade of forests have dark green leaves that increase their ability to catch any light that reaches the forest floor

Chameleon is a lizard that changes its color to match its surroundings at the time

Chameleon

Butterflies

Mimicry – an adaptation in which one species copies the appearance or behavior of another species

Recall the “Animal Camouflage” Article– Viceroy butterfly protects

itself by looking like the monarch butterfly, which birds avoid because of their bad taste

Adaptation Advantages

Decreases competition

Allows species niche to be different

Allows species survival

Behavioral Adaptations

The way an organism acts or responds to its environment in order to survive

Can be reflexive or instinctive

Reflexive Behaviors

A behavior that is triggered automatically by something outside an organism

The behavior happens without the organism thinking about it– Example: Pulling your hand off of something

hot– Example: Running from a loud noise

Instinctive Behaviors

A behavior that an organism carries out because it is genetically prone to do so

These are natural reactions– Examples: Traveling in a group (safety in

numbers)– To look bigger and more frightening a

blowfish expands its body with air– Male bioluminescent fireflies flash light to

attract females

Other Adaptations

Hibernation – animals decrease their activity during winter months after constant eating during the fall

Estivation – to avoid the heat of summer some frogs, lizards and ground squirrels sleep through the summer in a dormant state

Other Adaptations

Migration – allows animals to find more favorable climates or feeding conditions after a change in climate

Courtship Rituals

Instinctive behaviors because they encourage animal reproduction– Male birds use songs to

attract female birds

Structural adaptations – Male peacock struts using

his colorful tail feathers so females will notice him

Survival of the Fittest

Which will survive in the snowy climate of northern Alaska?– White rabbit with long thick fur or– Gray rabbit with short fur

Natural Selection

Most helpful traits are passed on to future generations – Charles Darwin

Process that makes it more likely that organisms with the best characteristics for survival in a specific environment will survive, reproduce, and pass on their advantageous genetic traits to offspring

Populations

In order to evolve so the most advantageous adaptations become common three things must happen

1. Trait must vary within the species

2. The adaptation must be one that parents can pass on to offspring genetically

3. One version of the adaptation must benefit the members to that they survive and reproduce more than the members who do not have it

May occur quickly or take millions of years

Amazing Adaptations

Ice fish – Evolved to have no

red blood cells and no hemoglobin

– Oxygen dissolves in the blood

– Allows fish to survive in the extreme cold

Human Impact

Negative– Destroying habitat

– Polluting rivers, lakes

Positive– Repair damage

already done– Protect whole

ecosystems (conserve plants and animals)

– Maintain biodiversity– Wildlife refuges– Protect endangered

species

Protecting Endangered Species

Government protected habitats

Bred in captivity and then returned to wild– Examples: bald eagle,

California condor

Restrictions to hunting

Bald Eagle

In 1700s population of 100,000 in 1970 population of less than 3,000

Cause – unregulated hunting and habitat destruction, DDT pesticide

DDT – caused eagles to produce eggs with shells that were too thin

Solution – Government protected eagle’s nest, bred in zoos, banned use of DDT

Population increased but still endangered

Bald Eagle

PABS

Pennsylvania Biological Survey (PABS)– Helps to maintain state’s biodiversity – Tracks and monitors plants and animals– Coordinates programs, surveys and research

on PA wildlife– Developing bio-reserves throughout PA

• Help conserve ecosystems throughout the state

Endangered Species Act

ESA – US law that governs the protection of species whose populations are in decline and could be in danger of extinction

The law forbids hunting, killing, collecting or harming of species listed as endangered or threatened.

3 categories – Threatened, Endangered, Extinct

ESA Categories

Threatened– A species that still has

many individuals in the wild but whose numbers are dwindling to a point at which the species could become endangered

– Example: Green snake

Endangered– A species that has so

few individuals remaining that extinction is a possibility in the near future

– Example: Delmarva fox squirrel

ESA Categories

Extinct– A species that no longer exists– Example: Passenger pigeon

Factors Prone to Extinction

Specific food requirementsSpecific habitat or nesting requirementsHigh on food chain or food web

– These animals are more vulnerable to pollution

MigrationReproduce a low rateLimited habitat range Interference with human activities

Help for Species in Danger

National Marine Fisheries Service and US Fish and Wildlife Service– Propose species the ESA will protect– Can delist species if species is no longer in

need of protection• Happened to bald eagle in 1999

Humans have accelerated extinction between 1,000 and 10,000 times