Key Thinking Skills of Evolution for Today These key thinking skills will be used today as we go through the lesson on biodiversity and biological evolution.

Key Thinking Skills of Evolution for TodayKey Thinking Skills of Evolution for Today • These key thinking skills will be used today as we go through These key thinking skills will be used today as we go through

the lesson on biodiversity and biological evolution. Keep the the lesson on biodiversity and biological evolution. Keep the following questions in mind as we go through the material.following questions in mind as we go through the material.• DetailsDetails

• What features characterize biodiversity and biological What features characterize biodiversity and biological evolution?evolution?

• Language of the DisciplineLanguage of the Discipline• What terms or words are specific to the study of What terms or words are specific to the study of

biodiversity and biological evolution?biodiversity and biological evolution?

Quote for Today“It is not the strongest of the species that survives,nor the most intelligent, but the one most responsiveto change.” – Charles Darwin

Essential Question & TermsEssential Question & Terms• Essential Question:Essential Question:

• Be able to describe how the Be able to describe how the earth is earth is ““just rightjust right”” for life. for life.

• What is evolution? What is evolution?

• How has evolution lead to the How has evolution lead to the current diversity of organisms?current diversity of organisms?

• What is an ecological niche?What is an ecological niche?

• How does it relate to adaptation How does it relate to adaptation to changing environmental to changing environmental conditions?conditions?

• How do extinction of species How do extinction of species and formation of new species and formation of new species affect biodiversity?affect biodiversity?

• Terms:Terms:• BiodiversityBiodiversity• Biological evolutionBiological evolution• ExtinctionExtinction• Chemical evolutionChemical evolution• Natural selectionNatural selection• AdaptationAdaptation• Prokaryotic cellsProkaryotic cells• Eukaryotic cellsEukaryotic cells• Gradualism punctuated Gradualism punctuated

equilibriumequilibrium• KingdomsKingdoms• Background extinctionBackground extinction• Mass extinctionMass extinction• Adaptive radiationAdaptive radiation

What types of Life What types of Life exist on the Earth? exist on the Earth?

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Types of OrganismsTypes of Organisms

• Prokaryotic Kingdom: Prokaryotic Kingdom: single-celled single-celled organisms containing no internal structures organisms containing no internal structures surrounded by membranes (therefore there surrounded by membranes (therefore there is no nucleus) is no nucleus) • MoneraMonera – bacteria and cyanobacteria – bacteria and cyanobacteria

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Types of OrganismsTypes of Organisms• Eukaryotic Kingdoms: Eukaryotic Kingdoms: all organisms consisting of all organisms consisting of

cells which contain membrane-bound nucleicells which contain membrane-bound nuclei• ProtistaProtista - mostly - mostly one-celled organisms – have one-celled organisms – have

characteristics of all three other Eukaryote Kingdomscharacteristics of all three other Eukaryote Kingdoms• Fungi - Fungi - organisms which decompose stufforganisms which decompose stuff • Plantae - Plantae - organisms which use photosynthesis to make organisms which use photosynthesis to make

their own food their own food • AnnualsAnnuals complete complete life cycle in one seasonlife cycle in one season• Perennials Perennials live for more than one seasonlive for more than one season

• Animalia - Animalia - organisms which must get organic organisms which must get organic compounds from food they eat - most are able to movecompounds from food they eat - most are able to move

• Invertebrates – Invertebrates – no backboneno backbone• Vertebrates – Vertebrates – Fish, Amphibians, Reptiles, Birds and Fish, Amphibians, Reptiles, Birds and

MammalsMammals 77

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Naming Naming SpeciesSpecies

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NAMING OF SPECIES

The system of naming species was first developed by Swedish botanist and physician, Carolus Linnaeus in the mid- 1700s•Taxonomy, which seeks to describe, name and classify organisms•begins with assigning all species a two-part Latin name called a binomial•first word of the binomial is the genus name of the species, • second word is the specific epithet for the species. 

• scientific name for the blue crab  is Callinectes sapidus• Callinectes, the genus name, is the collective term which

includes many species of crabs closely related to the blue crab

• sapidus, describes exactly which of the Callinectes species is being identified

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A phenotype is any observable characteristic or trait of an organism: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior (such as a bird's nest). •Phenotypes result from the expression of an organism's genes as well as the influence of environmental factors and the interactions between the two.The genotype of an organism is the inherited instructions it carries within its genetic code. •Not all organisms with the same genotype look or act the same way because appearance and behavior are modified by environmental and developmental conditions. •Similarly, not all organisms that look alike necessarily have the same genotype.

Definition of SpeciesDefinition of Species• Morphological Species Concept (MSC) Morphological Species Concept (MSC)

• traced back to the philosophies of Plato and traced back to the philosophies of Plato and Aristotle, and which Aristotle, and which continued to be used continued to be used until the first half of the twentieth centuryuntil the first half of the twentieth century

• defines species purely by their phenotypic defines species purely by their phenotypic traits rather than their genetic complement traits rather than their genetic complement or potential interbreedingor potential interbreeding

• number of species classified was large number of species classified was large because each group of individuals that because each group of individuals that exhibited a slight phenotypic difference exhibited a slight phenotypic difference were considered a different specieswere considered a different species

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Definition of Species• Biological Species Concept (BSC) Biological Species Concept (BSC)

• ‘‘a species is a group of interbreeding a species is a group of interbreeding populations that are genetically isolated populations that are genetically isolated from other groups by reproductive isolating from other groups by reproductive isolating mechanisms such as hybrid sterility or mate mechanisms such as hybrid sterility or mate acceptabilityacceptability’’

• Western meadowlarks (Western meadowlarks (Sturnella neglecta) and Sturnella neglecta) and Eastern meadowlarks (Sturnella magna) look Eastern meadowlarks (Sturnella magna) look almost identical to one another, yet do not almost identical to one another, yet do not interbreed with each other—thus, they are separate interbreed with each other—thus, they are separate species according to this definition.species according to this definition.

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Eastern MeadowlarkWestern Meadowlark

Definition of SpeciesDefinition of Species

• Phylogenetic Species Concept (PSC)Phylogenetic Species Concept (PSC)• Each population of sexually reproducing Each population of sexually reproducing

organisms that possesses at least one organisms that possesses at least one diagnostic character present in all diagnostic character present in all population members but absent from all population members but absent from all closest relatives is considered a speciesclosest relatives is considered a species

• each geographically distinct form is each geographically distinct form is classified as a speciesclassified as a species

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Definition of Species• Phylogenetic Species Concept (PSC)Phylogenetic Species Concept (PSC)

• In this example, In this example, Ensatina salamander lineages A and B Ensatina salamander lineages A and B are separate species. Each has a common ancestor that are separate species. Each has a common ancestor that individuals of other species do not. Even though it has individuals of other species do not. Even though it has diversified a lot, Lineage C is a single species, according diversified a lot, Lineage C is a single species, according to the phylogenetic species concept. None of the to the phylogenetic species concept. None of the subspecies of Lineage C has a single common ancestor subspecies of Lineage C has a single common ancestor separate from the other subspecies.separate from the other subspecies.

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EVOLUTIONisGradual Change

EVOLUTIONisGradual Change

OPARIN HYPOTHESISIn the 1930s, a Russian scientist, Alexander Oparin, hypothesized that life began in the oceans on early earth between 3.9 to 3.5 billion years ago. He suggested that first, simple organic molecules containing carbon formed. Energy from the sun, lightning, and earth's heat triggered chemical reactions to produce small organic molecules from substances present in the atmosphere. These molecules were organized by chance into complex organic molecules such as proteins, carbohydrates, and nucleic acids that are essential to life.

Chemical EvolutionOparin Hypothesis (early 1930s)Oparin Hypothesis (early 1930s)

1) 1) Formation of the planetFormation of the planet with gases in the with gases in the atmosphere that could serve as the raw atmosphere that could serve as the raw materials for life. materials for life. • most widely accepted astronomical theory for most widely accepted astronomical theory for

the origin of the earth and the rest of the solar the origin of the earth and the rest of the solar system is that the solar system formed about system is that the solar system formed about 4.7 billion years ago from a diffuse dust cloud 4.7 billion years ago from a diffuse dust cloud (Nebular Theory)(Nebular Theory)

• central portion probably condensed to form the central portion probably condensed to form the sun and areas in the outer parts of the cloud sun and areas in the outer parts of the cloud condensed to form the planetscondensed to form the planets

• beginning of the universe according to the "Big beginning of the universe according to the "Big Bang" theory occurred about 15 billion years Bang" theory occurred about 15 billion years agoago

Chemical EvolutionOparin HypothesisOparin Hypothesis

2) 2) Random synthesis of simple organic moleculesRandom synthesis of simple organic molecules (such as amino acids that make up proteins) (such as amino acids that make up proteins) from the gases in the surrounding atmosphere.from the gases in the surrounding atmosphere.

3) 3) Formation of larger, more complex moleculesFormation of larger, more complex molecules (Macromolecules) from the simple organic (Macromolecules) from the simple organic molecules, e.g., the formation of simple proteins.molecules, e.g., the formation of simple proteins.

4) 4) Formation of coacervatesFormation of coacervates - unique droplets - unique droplets containing the macromolecules , i.e., a containing the macromolecules , i.e., a coacervates consists of chemicals suspended coacervates consists of chemicals suspended within a liquid surrounded by a membrane, e.g. within a liquid surrounded by a membrane, e.g. a droplet consisting of chemicals in water a droplet consisting of chemicals in water surrounded by an oil layer membrane.surrounded by an oil layer membrane.

Chemical EvolutionOparin HypothesisOparin Hypothesis

5) 5) Development of some type of chemical Development of some type of chemical organizersorganizers that function to give these droplets that function to give these droplets the ability to take in molecules, discharge other the ability to take in molecules, discharge other molecules, and control and maintain a molecules, and control and maintain a characteristic chemical pattern. These chemical characteristic chemical pattern. These chemical organizers would probably be similar to nucleic organizers would probably be similar to nucleic acids (that make up chromosomes).acids (that make up chromosomes).

6) 6) Development of controlled reproductionDevelopment of controlled reproduction to to insure that resultant daughter cells have the insure that resultant daughter cells have the same chemical capabilities. The droplets could same chemical capabilities. The droplets could now be considered to be primitive cells.now be considered to be primitive cells.

7) 7) Beginnings of evolutionary developmentsBeginnings of evolutionary developments so so that a group of cells could adapt to changes in that a group of cells could adapt to changes in the environment over time.the environment over time.

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A phenotype is any observable characteristic or trait of an organism: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior (such as a bird's nest). •Phenotypes result from the expression of an organism's genes as well as the influence of environmental factors and the interactions between the two.The genotype of an organism is the inherited instructions it carries within its genetic code. •Not all organisms with the same genotype look or act the same way because appearance and behavior are modified by environmental and developmental conditions. •Similarly, not all organisms that look alike necessarily have the same genotype.

Definition of SpeciesDefinition of Species• Morphological Species Concept (MSC)

– traced back to the philosophies of Plato and Aristotle, and which continued to be used until the first half of the twentieth century

– defines species purely by their phenotypic traits rather than their genetic complement or potential interbreeding

– number of species classified was large because each group of individuals that exhibited a slight phenotypic difference were considered a different species 26

http://www.falcons.co.uk/mefrg/Falco/13/Species.htmhttp://www.falcons.co.uk/mefrg/Falco/13/Species.htm

Definition of Species• Biological Species Concept (BSC)

– ‘a species is a group of interbreeding populations that are genetically isolated from other groups by reproductive isolating mechanisms such as hybrid sterility or mate acceptability’

• Western meadowlarks (Sturnella neglecta) and Eastern meadowlarks (Sturnella magna) look almost identical to one another, yet do not interbreed with each other—thus, they are separate species according to this definition.

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http://www.falcons.co.uk/mefrg/Falco/13/Species.htmhttp://www.falcons.co.uk/mefrg/Falco/13/Species.htm

Eastern MeadowlarkWestern Meadowlark

Definition of SpeciesDefinition of Species• Phylogenetic Species Concept (PSC)

– Each population of sexually reproducing organisms that possesses at least one diagnostic character present in all population members but absent from all closest relatives is considered a species

– each geographically distinct form is classified as a species

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http://www.falcons.co.uk/mefrg/Falco/13/Species.htmhttp://www.falcons.co.uk/mefrg/Falco/13/Species.htm

Definition of Species• Phylogenetic Species Concept (PSC)

– In this example, Ensatina salamander lineages A and B are separate species. Each has a common ancestor that individuals of other species do not. Even though it has diversified a lot, Lineage C is a single species, according to the phylogenetic species concept. None of the subspecies of Lineage C has a single common ancestor separate from the other subspecies.

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http://www.falcons.co.uk/mefrg/Falco/13/Species.htmhttp://www.falcons.co.uk/mefrg/Falco/13/Species.htm

EVOLUTIONis

Gradual Change

EVOLUTIONis

Gradual Change

Miller-Urey Experiment• conducted in 1953 by Stanley Miller with Harold

Urey• the first experiment about the evolution of

prebiotic chemicals and the origin of life on Earth– mixture of methane, ammonia,

hydrogen, and water vapor introduced into a 5-liter flask (simulate the Earth's primitive, reducing atmosphere)

– energized by an electrical discharge apparatus to represent ultraviolet radiation from the Sun

– products were allowed to condense and collect in a lower flask which modeled a body of water on the Earth's surface

Miller-Urey Experiment– heat supplied to this flask recycled the water

vapor just as water evaporates from lakes and seas, before moving into the atmosphere and condensing again as rain

– after a day of continuous operation

•a thin layer of hydrocarbons on the surface of the water

– after about a week of operation

•a dark brown scum had collected in the lower flask and was found to contain several types of amino acids, including glycine and alanine, together with sugars, tars, and various other unidentified organic chemicals

The Just-Right Planet

Let’s test your knowledge!!!Play the animation above to see if you can get bacteria to form!!

Review of Miller-Urey Experiment

• What you need to make primitive Earth’s atmosphere:– Water vapor– Methane– Ammonia– Hydrogen– Spark (UV from the sun)

• What you get:– Collects and condenses to make water (Earth’s oceans)– Makes a dark brown scum (amino acids)

• Glycine• Alanine• Sugars• Tars• Other unidentified organic chemicals

Fossils• Oldest fossils are the

approximately 3.465 billion-year-old microfossils from the Apex Chert, Australia– colonies of

cyanobacteria (formerly called blue-green algae) which

built real reefs

Fossils1600's - Danish scientist Nicholas Steno studied the relative positions of sedimentary rocks

– Layering is the most obvious feature of sedimentary rocks• formed particle by particle and bed by bed, and

the layers are piled one on top of the other• any sequence of layered rocks, a given bed must

be older than any bed on top of it– Law of Superposition is fundamental to the

interpretation of Earth history, because at any one location it indicates the relative ages of rock layers and the fossils in them.

Half-life for a given radioisotope is the time for half the radioactive nuclei in any sample to undergo

radioactive decay

Half-life for a given radioisotope is the time for half the radioactive nuclei in any sample to undergo

radioactive decay