Threatened, Endangered and Extinct Species
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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
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