Chapter 4

Chapter Three Section Three Biodiversity and Extinction

Introduction There is no exact number of how many species are on earth but there have been about 1.5 identified.

Biodiversity is the number of different species in an area.

What do these two pictures have to do with biodiversity?There are still organisms that are yet to be discovered!!!!

Think of all the areas that humans have a hard time getting to.Deep ocean Tropical rainforestDeep within the earths crust The Value of Biodiversity There are three main reasons to preserve biodiversity:

Source of beauty and recreation Economic value Ecological value Economic Value Many plants and animals are economically valuable for humans.

Economic Value What do plants and animals give humans:Food Clothing MedicineOther products as well

Economical Value The ecosystems in which the organisms live are also valuable.Ecotourism is an important source of jobs and money.

Ecological Value We know from past units that all organisms in an ecosystem are connected to one another.

Organisms depend on one another for food and shelter.When there is a change that affects one organism it is going to affect others.Ecological Value A keystone species is a species that influences the survival of many other species.

Ecological Value http://www.youtube.com/watch?v=cKB5cI7geCg- Keystone species the honey bee

Factors Affecting Biodiversity Factors that affect biodiversity are:Area Climate Diversity of niches AreaWithin an area a large area would contain more species of organisms than that of a smaller area.Climate The number of species increase from the poles to the equator

Climate The ecosystems of Latin America, Southeast Asia, and Central Africa are the most diverse in the world.Covers about 7% of the worlds land mass but contains about 50% of the worlds plants and animals.Coral Reefs are another example they make up less than 1% of the ocean but contain about 20% of the worlds fish.Niche Diversity Coral reefs are the second most diverse ecosystem in the world.

A coral reef supports many different niches of an organism. It allows many different species to live in the reef than in a ecosystem that would support all similar organims.Gene Pool Diversity Organisms in a healthy population have a number of different traits.These traits are determined by the organisms genes.Genes are the structures in its cells that carry its hereditary information Found in the nucleus of every single cell in your body!!!!!

Gene Pool Diversity Species that lack a diverse gene pool are less able to adapt in order to survive.

Species that have a diverse gene pool are more able to adapt in order to survive.Extinction of Species The disappearance of all organisms from earth is called Extinction

Extinction of species Species in danger of becoming extinct is called endangered species

Extinction of SpeciesSpecies that could become endangered in the near future are called threatened species

Causes of Extinction There are four major causes of extinction:Habitat destruction Poaching Pollution Exotic species Habitat Destruction The largest cause of extinction of species is habitat destruction or the loss of a natural habitat

Poaching The Illegal killing or removing animals from their natural habitat is called poaching.

Many endangered or threatened animals are hunted for their teeth, horns, skin, and fur.

Pollution Some species are endangered because of pollution.The pollutants affect the animals water they drink and the air the breath.

Exotic Species Introducing exotic species into an ecosystem can threaten biodiversity.http://www.youtube.com/watch?v=R2kV5uXLLu4 invasive species

Protecting Biodiversity There are three successful approaches to protecting biodiversity.Captive breeding Laws and treaties Habitat preservation Captive Breeding Captive breeding is the mating of young animals in zoos or animals preserves

Laws and Treaties The most important treaty protecting wildlife is the Convention of International Trade in Endangered Animals.More than 800 endangered or threatened animals cannot be traded for profit Habitat Preservation The most effective way to preserve biodiversity is to protect the whole ecosystem in which the organisms are found.Chapter 4Section One Fossils Introduction Fossils are the preserved remains or traces of living things

How a Fossil Forms Most fossils form when living things die and are buried by sediments. The sediments slowly harden into rocks and preserve the shapes of the organisms How a Fossil Forms Fossils are normally found in sedimentary rock.

Sedimentary Rock- is the type of rock that is made of hardened sediment

How a Fossil Forms Sedimentary rock is made of rock particles and the remains of living things.

Examples:CoalSandstoneLimestone

http://www.brainpop.com/science/diversityoflife/fossils/

How a Fossil Forms An animal dies and sinks into shallow waterSediment covers the animal The sediment becomes rock, (only the hard parts of the animals) preserving parts of the animal Weathering and erosion eventually expose the fossil at the surface.How a Fossil Forms Fossils found in rock include molds and casts, petrified fossils, carbon films and trace fossils

Other fossils form when the remains of organisms are preserved in substances such as tar, amber, or ice.Molds and CastsFossils fall into the following categories:Mold Cast Petrified Carbon films Trace fossil Preserved remains Mold and CastMold is a hallow area in sediments in the shape of an organism or part of an organism

Cast is a solid copy of the shape of an organism Opposite of the mold Both preserve details of the animals structure

Petrified Fossil The term petrified means turned to stone

Petrified Fossils are fossils in which minerals replace all or part of an organismOvertime minerals fill in all the spaces and harden to preserve the fossil

Carbon Films Carbon film an extremely thin coating of carbon on rockThis type of fossil preserves the delicate parts of plant leaves and insects

Trace Fossils Trace Fossils provide evidence of the activities of ancient organisms Example:Dinosaur footprint

Trace Fossils From fossil footprints, scientists can find answers to questions about an animals size and behavior.

Other trace fossils give evidence about where the organism lived or how it obtained its food Preserved Remains There are some fossils that preserve the organism with little or no change They can be preserved in:Tar AmberFreezing

Change Over Time Scientist who study fossils are called paleontologists

They use information to determine what past life forms were like Change Over TimeThe fossil record provides evidence about the history of life and past environments on earth.The fossil record also shows that different groups of organisms have changed over time.Fossils and the Past EnvironmentsInformation gathered from the fossils provide information so scientists build a picture of what environment was like.

Fossils tell about:Climate changes Changes to earths surface Change and the Fossil Record The fossil record reveals a surprising fact: Fossils occur in a particular order.Older rocks contain simpler organisms Younger rocks show more complex organism Change and the Fossil Record This Means:THE FOSSIL RECORD SHOWS THAT LIFE ON EARTH HAS EVOLVED OR CHANGED OVER TIME

Simple organisms, gave rise to more complex organisms The fossil record provides evidence to support the theory of evolution.

Evolution is the gradual change in living things over long periods of timeFossils show:Millions of types or organisms have evolved Millions of types of organisms have gone extinctChapter Four Section 2The Relative Age of Rocks Introduction There are two ways to express the age of a rock and any fossil in it contains.

Relative age of a rock is its age compared to the ages of other rocks

Absolute age is the number of years since the rocks formation The Position of Rock LayersIt can be hard to determine the absolute age of a rock.

Geologist use the law of superposition to determine age The Position of Rock LayersAccording to the law of superposition, in horizontal sedimentary rock layers the oldest layer is at the bottom.Each higher layer is younger then the layers below it

Determining Relative Age To determine relative age, geologists also study: extrusions of igneous rocks intrusions of igneous rocks faults Gaps in geologic record Clues From Igneous RockIgneous Rock forms when magma, or lava hardens

Lava that hardens on the earths surface is called extrusion An extrusion is always younger then the rocks below it.

Beneath the surface, magma may push into bodies of rock. There the magma cools and hardens into a mass of igneous rock called intrusion Intrusion is younger then the rocks around it

Clues From FaultsA fault is a break in earths crust.

Forces inside Earth cause movement of rocks on opposite sides of a fault

A fault is always younger then the rock it cuts through

Movement along faults can make it hard for geologists to determine the relative ages of rock layersGap in the Geologic Record Geologic record of sedimentary rock layers is not always complete

Sedimentary rock layers build on top of one another over time Some layers erode away exposing older rock Sedimentary rock build upon the exposed older rock

The surface where new rock layers meet a much older rock surface beneath them is called an unconformity Using Fossils to Date Rocks Certain fossils called index fossils, help geologists match rock layers.

To be useful as an index fossil, a fossil must be widely distributed and represent a type of organism that exists only briefly A fossil is considered widely distributed if it occurs in many different areas.

Index fossils are useful because they tell the relative ages of rock layers in which they occur Ammonite make good index fossilsWidely distributedMany evolved and then became extinct