Evolution Presentation for Biology Keystone

Hello class my name is Ms. Fisher and I will be your substitute Science teacher for the next week. Get ready to have a fantastic discussion on the topic of Evolution!

Icebreaker: Before I became a substitute teacher do you want to know where I worked? Hmmmm ????????????

A Forensics Lab Gas Chromatography Department

Famous person I worked on while I was in forensics:Anna Nicole SmithAnna Nicole Smith had "high" amounts of chloral hydrate metabolites in her system. But she was also on prescription medication Ativan, Klonopin and Valium which are all central nervous system depressants. At higher amounts, these drugs depress respiratory centers and circulatory centers.

Friday: February 17th Agenda1.)Introductions (Icebreaker)2.)Awesome Answer Bin/Reward System (Explain)3.) Begin Evolution PowerPoint4.) Begin Evolution Packet5.) Show small segment of Darwin & the Galapagos Islands YouTube video I inserted into the Evolution PowerPoint.Objective for today:Explore the definition of evolution. Through open discussion and utilization of my PowerPoint, you will begin to complete your evolution packet.

Ms. Fisher 2/ 17/12Evolution and Natural SelectionReview Presentation for Biology Keystone Assessment

Table of Contents1) What is Evolution?2) Natural Selection 3) Evidence for Evolution4) Evolution in ActionImportant things to consider:No individual organism can evolve, but given the right conditions over enough time, traits within a population will gradually change until the entire population is different.Populations tend to evolve to external environmental factors such as predators, food sources, and changes in climate.New species arise through this very process, and all life on earth can be traced back to simpler common ancestors.1) What is Evolution?Evolution the process by which species gradually change over many generations through natural selection. Species Adaptation Micro-evolution Macro-evolution A group of organisms that evolved together and are genetically similar enough that they can mate and produce fertile offspring.A specific physical trait or instinctual behavior that has evolved within a species to help it survive in its environment.Evolution within a species over several generations.Long term evolution over thousands of generations or more, leading to the origination of new species (called speciation).Some More VocabularyIf one population becomes separated into two isolated groups, given enough time, the two groups will become different species.Common ancestor of species A1 and A2.Two distinct species, no longer capable of interbreeding.SpeciationKeep in mind, there really is no difference between micro and macro-evolution, except the amount of time. Species ASpecies A1Species A2Darwins Tree of LifeOuter twigs represent species.Kingdoms and phyla represented by the thicker branches of the tree.Splitting branches show new species branching off from a shared ancestor.Closely related species branched off from each other more recently.Distantly related species branched off much closer to the bottom.All the species share a common ancestor at the trunk of the tree.

Common ancestor (shared by all the descendants)Speciation & Darwin

http://www.youtube.com/watch?v=l25MBq8T77w

Finches (birds) are separated on different islands and eventually develop different traits.

Why? Each island has a slightly different environment therefore, the birds that dwell on each island must develop traits that will help them survive on that island.

The finches develop different beak sizes to successfully eat their food.All these species trace their lineage back to this common ancestor, essentially the first mammal.

A dead end branch represents an extinction.Where is the most recent common ancestor between squirrels and whales?The Mammalian Family Tree13sharkgoldfishfrogalligatorchickenplatypusmonkeypigcowMore related to a cowLess related to a cowPigs and cows have a relatively recent common ancestor.Sharks and cows have a very ancient common ancestorAll vertebrates trace back to this common ancestor.The Tree of Life: Another ViewNatural Selection The driving mechanism behind evolution, as explained in Darwins Origin of SpeciesCertain organisms survive to pass on their traits to successive generations, but most do not.Often summed up as survival of the fittest

2) Natural Selection Charles DarwinThomas Malthus

No population can grow indefinitely. Many more offspring are born than will actually survive to pass on their genes. Therefore, individuals must compete for resources to survive.Darwins work was heavily influenced by the previous ideas of other naturalists, including Malthus research on population.For example:

If every baby robin survived to adulthood and reproduced, it would only take a few decades before the entire planet would be overrun by robins!Struggle For Existence

Obviously, this does not happen!Darwin recognized that limited resources in any environment leadHowever slight this to a struggle for existence, in which the traits of some individualswill give them an advantage over others. advantage, it will lead to certain traits being selected by natureto survive and reproduceHence, natural selection! Artificial Selection

Darwin also realized that natural selection is basically the same process that humans have used for centuries in selective breeding of domesticated animals as well as plants for agriculture. These pigeons have all been bred by humans to have certain exaggerated characteristics. Artificial Selection

Selective breeding, or artificial selection is the same process that has led to all the variation we see in dog breeds today.In artificial selection, humans speed up the change in traits by doing the selecting themselves. In natural selection, nature itself is doing the selecting over thousands of generations.Where did all the millions of species come from?The mechanism (driving force) for evolution, as explained by Charles Darwin.Explains changes in an entire species or population (not individuals) over time.

Darwin knew thisNatural Selection

2) MutationsRandom changes in DNA are sometimes passed on to offspring.Some helpful; some harmful; some neutralOnly traits that increase reproductive fitness will continue to be passed on.

Darwin didnt know this because he didnt know about

DNA

ATGCDeoxyribonucleic Acid

DNAIronically, Darwin never found out about the work of Gregor Mendel, who was experimenting with pea plants right around the same time, in order to figure out how traits are inherited.

It was decades later that Mendel was finally recognized as the father of genetics.For Darwin, this was the one missing piece of the puzzle that would have vindicated his entire theory.It wouldnt be until 1953 that the genetic code itself was finally cracked by Watson and Crick in their discovery of the double-helix structure of DNA.Gene

Allele

Genotype

Phenotype A section of DNA that codes for a particular protein, physical trait, or functionOne of two (or more) different forms of a gene; For example, for the eye color gene, one allele codes for blue eyes, while the other codes for brown. Often, one allele is dominant over the other.The combination of alleles for a particular gene; one allele comes from the mother and the other from the father.The trait that results from the genotype Some Genetics Vocabulary

Genes are made up of complex combinations of the base pairs. Some genes code for proteins and enzymes. Some genes turn other genes on or off. Large sections of DNA code for NOTHING!Genes and ChromosomesA G TC

DNA replicationIf stretched out, the DNA from the nucleus of each cell in your body would be over 6 feet long!There are over 50 trillion cells in your body!Billions of DNA bases have to be copied every time your body makes new cells, which happens continuously.MutationsA mutation is simply when there is an error in this copying process.This happens all the time!When the right kind of mutation happens in the right kind of way, the mutated gene becomes part of the gene pool and natural selection continues.

MutationsKeep in mind:

Mutations themselves are random mistakes, but natural selection is not random! The tiniest genetic change will be favored if it increases an organisms chances for survival or reproduction, even the slightest bit.These tiny changes accumulate over the course of millions of years until the descendants have gradually diverged from their ancestors into a new species (or multiple different species).Assessment:Objective for today:Explore the definition of evolution. Through open discussion and utilization of my PowerPoint, students will begin to complete their evolution packet.What do we know about evolution? What is evolution?Evolution the process by which species gradually change over many generations through natural selection. Natural Selection the driving mechanism behind evolution as explained by Darwin. Survival of the fittest.

Ms. Fisher 2/17/12