Post on 16-Dec-2015
Lesson 6.1Objectives How scientists use fossils to learn about the history
of life How organisms evolved more complex forms over
time About mass extinctions
Fossil Record – information provided by fossil records and their location.
Fossil record lets scientists identify periods during which different species existed.
Cyanobacteria – earliest known organisms in the fossil record
◦ Contained chlorophyll and used photosynthesis to make sugars from carbon dioxide
◦ The bacteria produced oxygen as a by-product of photosynthesis
The first eukaryotes were single-celled
The oldest eukaryotes are from algae that lived 2 billion years ago.
600 mya the first multicellular animals (jelly-fish like) evolved.
Bacteria and algae – first life forms on land
Primitive insects – first land-dwelling animals
The loss of all the members of a species
Mass extinctions – several periods of huge numbers of species have become extinct in a very short time
Permian extinction – the largest mass extinction in Earth’s history.
Cretaceous Extinction – dinosaurs extinction
Lesson 6.2Objectives•About early ideas and observations on evolution•How Darwin developed his theory of natural selection•How new species arise
Refers to the process through which species change over time
French naturalist Proposed that during the
organism’s lifetime, they change in response to their environment
Example – giraffes long neck
British naturalist He published a book about a voyage in
Galapagos island Beagle – the name of a British navy ship
The book described his observations about how evolution works
Galapagos Island
Darwin observe several types of: Tortoises Finches
According to Darwin: Individuals that are best suited to their
environment survive and reproduce at a higher rate than other members of species in that environment
Overproduction
Variation
Adaptation
Selection
Population – is a group of similar species
In nature, organisms reproduce a lot but not many can survive.
Variation or differences among individuals
Genetic variation happens when offspring get a mix of chromosomes from both parents
An inherited trait that gives an organism’s an advantage in its particular environment
Individuals that adapted in their environment have a good chance of survival.
The adaptive trait will be passed on to their offspring.
Overtime, the useful trait will become more common in the population
The evolution of a new species from an existing species.
Isolation is the key factor that leads to speciation
Lesson 6.3Objectives•How populations increase and decrease in size•What factors affect population size and survival•How species can become extinct
All populations have the ability to grow rapidly over time
Populations tend to remain about the same size
Population increase through births and immigration
Immigration – the movement of individuals into a population
Emigration – the movement of individuals out of the population
Limiting factors:RESOURCESCOMPETITIONPREDATORSDISEASECATASTROPHIC EVENTS
Lesson 6.4Objectives•How scientists develop theories•About the evidence Darwin used to support the theory of natural selection•About additional evidence most scientists use today
Theory – is an explanation of natural phenomena based on a wide range of scientific evidence
Ancestor – is an early form of an organism from which later forms descend
Vestigial Organs – are structures that were fully developed in ancestral organisms but are reduced and unused in later species
Fossils provided evidence that species in the past were very similar to species living in Darwin’s time
Vestigial Organs - similar structures with different functions
Similarities in Development
DNA contains the information that organisms need to grow and to maintain themselves.
When organisms reproduce, they pass on their genetic material to their offspring