Diversity, Adaptation and Diversity, Adaptation and Change in EcosystemsChange in Ecosystems

Biodiversity and ClassificationBiodiversity and Classification • Scientists estimate that there are between Scientists estimate that there are between

2 and 4.5 million different types of 2 and 4.5 million different types of organisms on the planet. Likely there are / organisms on the planet. Likely there are / were many more. To organize, name and were many more. To organize, name and group these organisms based on similar group these organisms based on similar characteristics, scientists use a system characteristics, scientists use a system called taxonomy.called taxonomy.

• Taxonomy Taxonomy – the science of – the science of classification according to presumed classification according to presumed relationships among organisms.relationships among organisms.

• Scientists use a hierarchical system, Scientists use a hierarchical system, where organisms are classified in a where organisms are classified in a series of smaller groups.series of smaller groups.

Hierarchical SystemHierarchical System

• Domain- Bacteria, Eukarya, ArcheaDomain- Bacteria, Eukarya, Archea• Kingdom Kingdom – Monera, Protista, Plantae, Fungi, – Monera, Protista, Plantae, Fungi,

AnimaliaAnimalia• PhylumPhylum – sub-groups of each kingdom – sub-groups of each kingdom• Class Class • OrderOrder• FamilyFamily• GenusGenus • SpeciesSpecies – organisms that are very similar – organisms that are very similar

and can naturally interbreed to produce and can naturally interbreed to produce fertile offspringfertile offspring

Most General

Most Specific

Binomial NomenclatureBinomial Nomenclature• When organisms are assigned a scientific When organisms are assigned a scientific

name, the name is given in two parts, name, the name is given in two parts, Genus species,Genus species, and the name is either and the name is either written in written in italicsitalics or or underlinedunderlined. This . This system is called system is called binomial binomial nomenclature.nomenclature.

• Genus name indicates organisms that are Genus name indicates organisms that are similar, and is always capitalized.similar, and is always capitalized.

• Species name indicates organisms that are Species name indicates organisms that are different, and is written in lower case.different, and is written in lower case.

• Ex. Ex. Canis lupisCanis lupis wolfwolf Canis domesticusCanis domesticus dogdog

The 5 KingdomsThe 5 Kingdoms• ProkaryotaeProkaryotae – includes the bacteria – includes the bacteria

(eubacteria and archaebacteria (unicellular (eubacteria and archaebacteria (unicellular with no cell nucleus)with no cell nucleus)

• ProtistaProtista – includes single celled plants and – includes single celled plants and animals and algae (unicellular with a nucleus)animals and algae (unicellular with a nucleus)

• FungiFungi – includes the mushrooms, yeasts, – includes the mushrooms, yeasts, moulds (multicellular, decomposers)moulds (multicellular, decomposers)

• PlantaePlantae – includes the trees, flowers, mosses – includes the trees, flowers, mosses and ferns (multicellular, photosynthesizers)and ferns (multicellular, photosynthesizers)

• AnimaliaAnimalia – includes sponges, worms, – includes sponges, worms, crustaceans, insects, and mammals crustaceans, insects, and mammals (multicellular and heterotrophic)(multicellular and heterotrophic)

• Naming some 2 – 5 Naming some 2 – 5 million organisms million organisms presents a challenge to presents a challenge to scientists. To scientists. To overcome this overcome this challenge, challenge, dichotomous keysdichotomous keys are used to identify and are used to identify and classify organisms classify organisms based on their based on their characteristics.characteristics.

• Dichotomous Key

• Scientists today believe Scientists today believe that organisms that organisms changed over time. changed over time.

PhylogenyPhylogeny • the history of the history of

evolution of a evolution of a species or group species or group of organisms. of organisms. This history, and This history, and the evolutionary the evolutionary relationships relationships between between organisms is organisms is often shown in a often shown in a phylogenetic phylogenetic tree.tree.

EvolutionEvolution

The theory that changes occur and can been seen in the inherited traits of a population from 1 generation to another

Evidence of Evolution – FossilsEvidence of Evolution – FossilsPaleontologyPaleontology (the study of fossils) has (the study of fossils) has

provided scientists with an historical record provided scientists with an historical record of organisms that once lived. Fossil of organisms that once lived. Fossil evidence has also revealed a number of evidence has also revealed a number of patterns:patterns:

1. In the past, the earth was home to species 1. In the past, the earth was home to species that are very different from those that exist that are very different from those that exist today. today.

2. The complexity of living organisms seems 2. The complexity of living organisms seems to have increased from the past to the to have increased from the past to the present in a systematic manner.present in a systematic manner.

3. Living species and their fossil matches are 3. Living species and their fossil matches are found in the same geographical regions.found in the same geographical regions.

Dating the PastDating the Past

• Radioactive elements lose particles (and Radioactive elements lose particles (and mass) as they decay at a constant rate mass) as they decay at a constant rate (despite temperature, moisture or (despite temperature, moisture or pressure). Radioactive decay can be used pressure). Radioactive decay can be used as an accurate a measure of the age of an as an accurate a measure of the age of an object. The half-life of an object is the object. The half-life of an object is the length of time it takes for half the sample length of time it takes for half the sample to decay and become stable. By to decay and become stable. By measuring the age of rock in which fossils measuring the age of rock in which fossils are found, paleontologists can estimate are found, paleontologists can estimate the age of the fossils, creating a the age of the fossils, creating a chronological evolutionary scale.chronological evolutionary scale.

BiogeographyBiogeography

• Biogeography studies the distribution of Biogeography studies the distribution of different organisms on the surface of the different organisms on the surface of the earth. Over long periods of time, the Earth’s earth. Over long periods of time, the Earth’s continents have shifted position, re-continents have shifted position, re-distributing living organisms. The continents distributing living organisms. The continents can be matched up geographically and can be matched up geographically and biologically. Some islands are far away from biologically. Some islands are far away from land and host a unique set of organisms. The land and host a unique set of organisms. The evolutionary pressures and past of these evolutionary pressures and past of these isolated organisms can also be studied.isolated organisms can also be studied.

• Essentials of Geology : Chapter 2 : Animations• Example: Pangea and the idea that similar Example: Pangea and the idea that similar

organisms exist on 2 different continents organisms exist on 2 different continents (Bison in Northern Canada and Bison in Russia)(Bison in Northern Canada and Bison in Russia)

Anatomical EvidenceAnatomical Evidence

• Scientists can study similarities and Scientists can study similarities and differences in the anatomy of differences in the anatomy of organisms and in their embryological organisms and in their embryological development to determine ancestral development to determine ancestral links between organisms.links between organisms.

Homologous structuresHomologous structures

- features with similar - features with similar structures, and different structures, and different functions that indicate functions that indicate an evolutionary an evolutionary relationship between relationship between organisms. organisms.

- Shows evolution from a - Shows evolution from a common ancestorcommon ancestor

Ex. bat wing and human Ex. bat wing and human handhand

Ex. dolphin flipper and Ex. dolphin flipper and forelimb of a dogforelimb of a dog

Analogous structuresAnalogous structures

– – features with similar features with similar functions, but very functions, but very different structures different structures that indicate there is that indicate there is little evolutionary little evolutionary link between link between organisms.organisms.

-Shows no common -Shows no common ancestorancestor

Ex. bat wing and Ex. bat wing and butterfly wingbutterfly wing

Vestigial featuresVestigial features

• rudimentary structures that have no clear rudimentary structures that have no clear function that may have once been function that may have once been important, but are evolving out of important, but are evolving out of existence.existence.

• Ex. Appendix & tailbone of humans, small Ex. Appendix & tailbone of humans, small foot found on some snakesfoot found on some snakes

Biochemical EvidenceBiochemical Evidence • Scientists believe that the Scientists believe that the amino acidamino acid

sequences in sequences in proteinsproteins or related organisms or related organisms are more similar than those in unrelated are more similar than those in unrelated organisms. organisms. DNA sequencesDNA sequences that make up that make up different genes control the traits an organism different genes control the traits an organism will have. More similar organisms will have will have. More similar organisms will have more similar DNA.more similar DNA.– Ex. Monkeys and humans share about 94% of the Ex. Monkeys and humans share about 94% of the

same genetic information and about 90% of the same genetic information and about 90% of the same amino acids.same amino acids.

• Other examples are: waste products Other examples are: waste products (nitrogenous waste), hormones, chromosomes(nitrogenous waste), hormones, chromosomes

Theories of EvolutionTheories of Evolution

Lamarck –Inheritance of Lamarck –Inheritance of Acquired CharacteristicsAcquired Characteristics

• Lamark believed that organisms Lamark believed that organisms would would desiredesire to evolve and to evolve and develop a certain trait that they develop a certain trait that they required required withinwithin a life time to a life time to survive and would lose un-survive and would lose un-necessary traits necessary traits (‘Use-Disuse’ (‘Use-Disuse’ TheoryTheory). He also suggested that ). He also suggested that these traits could be passed down these traits could be passed down to offspring (to offspring (InheritanceInheritance). Ex. if a ). Ex. if a giraffe needed along neck to giraffe needed along neck to reach food, the long neck would reach food, the long neck would evolve as the giraffes spent many evolve as the giraffes spent many generations reaching for food.generations reaching for food.

Giraffe EvolutionGiraffe Evolution

Darwin – Natural Selection, Darwin – Natural Selection, Survival of the FittestSurvival of the Fittest

• Darwin believed that there were Darwin believed that there were many many variationsvariations among organisms. among organisms. Traits that were better adapted to Traits that were better adapted to survival and reproductive success, survival and reproductive success, would be passed down to future would be passed down to future generations generations (Inheritance).(Inheritance). Darwin’s Darwin’s theory required that:theory required that:

Darwin’s theory required that:Darwin’s theory required that:

1. 1. VariationsVariations exist among organisms. exist among organisms.2. In a changing environment, specific 2. In a changing environment, specific

variations were better variations were better adaptedadapted to to survival than others.survival than others.

3. Only those organisms that survive (and 3. Only those organisms that survive (and have the adaptive traits) will sexually have the adaptive traits) will sexually reproduce. reproduce. ‘Survival of the Fittest’‘Survival of the Fittest’

4. The adaptive traits will be passed down 4. The adaptive traits will be passed down to the offspring.to the offspring.

5. **5. **Natural SelectionNatural Selection always occurs, each always occurs, each trait has a chance to be passed on, but trait has a chance to be passed on, but its likely the better trait would be passedits likely the better trait would be passed

Sources of VariationSources of Variation

• MutationsMutations – are random changes in the – are random changes in the DNA sequence of a chromosome. DNA sequence of a chromosome. Mutations may be:Mutations may be:– neutral – have no effect on an individualneutral – have no effect on an individual– harmful – hinder survival or reproductive harmful – hinder survival or reproductive

success (selected against and may disappear)success (selected against and may disappear)– beneficial – improve survival or reproductive beneficial – improve survival or reproductive

success (selected for and accumulate)success (selected for and accumulate)

•Example: Bacteria mutating to become Example: Bacteria mutating to become resistant to drugs like antibiotics.resistant to drugs like antibiotics.

– Most biological diversity in organisms is due to Most biological diversity in organisms is due to mutationsmutations

• Sexual ReproductionSexual Reproduction – involves the – involves the production of an organism from two different production of an organism from two different parents. The offspring inherits ½ the genetic parents. The offspring inherits ½ the genetic characteristics of both parents, increasing characteristics of both parents, increasing variability.variability.– Each parent has two (different) copies of Each parent has two (different) copies of

each gene, but only passes one copy to the each gene, but only passes one copy to the offspring.offspring.

– The copy that is inherited by the offspring is The copy that is inherited by the offspring is randomlyrandomly determined. determined.

– Sexually reproducing organisms choose Sexually reproducing organisms choose different mates giving rise to many different different mates giving rise to many different possible combinations (variation). possible combinations (variation).

– Sexual reproduction usually removes/masks Sexual reproduction usually removes/masks abnormal/faulty genesabnormal/faulty genes

• Asexual ReproductionAsexual Reproduction – involves – involves the production of an individual from the production of an individual from one parent. The offspring is one parent. The offspring is genetically identicalgenetically identical to the parent. to the parent.

• Example: CloningExample: Cloning– Cloning decreases genetic Cloning decreases genetic

diversity/variation and could possibly diversity/variation and could possibly cause an unstable population.cause an unstable population.

Speciation and EvolutionSpeciation and Evolution• SpeciationSpeciation is the formation of a new species. It is the formation of a new species. It

can occur by a step by step process known as can occur by a step by step process known as allopatric speciationallopatric speciation..1. A 1. A physical barrierphysical barrier separates a population into separates a population into two isolated groups.two isolated groups.2. 2. Environmental pressuresEnvironmental pressures on the two groups on the two groups are very different causing the populations to are very different causing the populations to evolve independently.evolve independently.3. Over time the accumulated differences 3. Over time the accumulated differences between populations become so extreme, the between populations become so extreme, the populations can populations can no longer interbreed to no longer interbreed to produce fertile offspringproduce fertile offspring. (They are two . (They are two different species).different species).

Tutorial 24.1 Speciation Mechanisms

• Theory of gradualism –Theory of gradualism –speciation speciation takes place very slowly. Due to takes place very slowly. Due to Natural selectionNatural selection

• Theory of punctuated equilibrium Theory of punctuated equilibrium –– species evolve in bursts very rapidly, species evolve in bursts very rapidly, followed by longer periods of stability followed by longer periods of stability (little change). Again, due to natural (little change). Again, due to natural selectionselection

• Divergent evolutionDivergent evolution – the – the evolution into many different evolution into many different species.species.– Due to Due to differentdifferent environmental environmental

pressurespressures– Usually due to a Usually due to a barrier:barrier:

•Physical: island Physical: island formation/wall/mountain/etcformation/wall/mountain/etc

•Biological:pheromones/Biological:pheromones/enemiesenemies

• Convergent evolutionConvergent evolution – the – the development of similar development of similar appearance, structure or appearance, structure or behaviors in unrelated species behaviors in unrelated species due to due to similarsimilar environmental environmental pressurespressures..