Speciation

Speciation 300 Biology Gb2014

IntroductionComplete the Moodle pretopic Quiz: http://learningon.theloop.school.nz/moodle/mod/quiz/view.php?id=68826

http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html

Achievement StandardEvolutionary processesinvolve the following biological ideas:Role of mutationGene flowRole of natural selection and genetic driftModes of speciation (sympatric, allopatric)Reproductive isolating mechanisms that contribute to speciation (geographical, temporal, ecological, behavioral, structural barriers, polyploidy)Patterns such as divergence, convergence, adaptive radiation, co-evolution, punctuated equilibrium, and gradualism.Scientific evidence for evolution, which may include examples from New Zealands flora and fauna, will be selected from:fossil evidenceComparative anatomy (homologous and analogous structures)Molecular biology (proteins and DNA analysis)Biogeography.

The BasicsTerms:Genes carry the genetic information required for cell growth, functioning and replication

Alleles alternative form of a gene (creates variation)

Gene Pool all the alleles of a population

Gene Flow movement of alleles in and out of a population

Speciation - evolution of new species, new species cannot reproduce with old species

Mutation change in the base sequence in DNA, must occur in gametes to be passed on. Creates totally NEW phenotypes.

Changes in Allele FrequenciesBottleneck Effect massive loss of alleles due to natural disaster, leaves a non representative population

Founder Effect small non representative group migrate to a new habitat

Genetic Drift random loss of alleles due to chance in a small population

TasksComplete workbook pages 171-173

Complete Worksheet: Gene Frequency Questions

Complete Gene Pools Moodle Quizhttp://learningon.theloop.school.nz/moodle/mod/quiz/view.php?id=68828

Kahoots Genetic Drift Basicshttps://play.kahoot.it/#/?quizId=a4f952ba-9dcb-4995-a247-75d30a8af5d8

Natural SelectionOrganisms best suited to their environment mate and pass on their genes to the next generation increasing the number of these helpful genes in the gene pool, meanwhile those unsuited do not mate and those genes disappear from the gene pool.

Stabilizing selects against the two extremes and favors the middle (2)

Directional selects against one of the extremes (3)

Disruptive selects against the middle and favors the two extremes, this can lead to speciation (1)Complete Workbook pages 164-170

VariationDifferences between individuals in a species, caused by differences in the DNA base sequence

The more differences in a species the greater chance that some of the species will survive changes within their environment

Variation is created during sexual reproduction, meiosis (crossing over, independent assortment, segregation) immigration and mutations

Variation must occur within the gametes in order to be passed on

Variation is reduced by natural selection, genetic drift (bottleneck effect, founder effect), emigration and natality.

Cline SpeciationCline Speciation continuous gradient of different but interbreeding organism

Ring Speciation continuous gradient that moves in a circle and meets up at the two ends at which point the two species rarely interbreed as have evolved differently

TasksRead pathfinder pages 11-15, answer questions 2, 4, 6, 7Complete Moodle Natural Selection Quiz http://learningon.theloop.school.nz/moodle/mod/quiz/view.php?id=68847Complete the following online activitieshttp://ats.doit.wisc.edu/biology/ev/ns/t2_a1.htmhttp://ats.doit.wisc.edu/biology/ev/ns/t3_a1.htm

SpeciationOne species evolves into two or more species that can no longer interbred.

Usually occurs as a result of adaptation to new ecological niches and in response to the occurrence of new variations within the species that make an organism better able to survive and reproduce

SpeciationThere are three ways in which new species can evolve:

Instant SpeciationOccurs within one generation as a result of polyploidy more than two sets of chromosomesUsually occurs in plants

Speciation2. Sympatric SpeciationOccurs when a new species arises in the SAME territory as the parent speciesOften occurs as a result of niche differentiation (ie finches living in top of trees vs forest floor)

3. Allopatric SpeciationOccurs when a new species evolves as a result of being isolated from the parent speciesNEW territoryOften occurs when there is some kind of geographical or environmental disturbance

Tasks:Complete worksheet: More Speciation Questions

Complete workbook pages 178-181

Complete this online activities:http://ats.doit.wisc.edu/biology/ev/sp/t1_a.htm http://ats.doit.wisc.edu/biology/ev/sp/t2_tabs.htm

Kahoots: Speciation https://play.kahoot.it/#/?quizId=f29c2dc5-9acb-4615-96c8-8f5c887a6573

Polyploidy and AneuploidyPoly many, polyploidy = more than one set of chromosomes

Aneu one, aneuploidy = one chromosome is represented three times instead of the usual two (one from each parent)

Homologous Chromosomes usually separate during meiosis to create two gametes with haploid (n, half the original) chromosomes

Non DisjunctionNon disjunction when homologous pairs of chromosomes fail to separate during meiosis the gametes can end up with:Having two copies of a single chromosome (aneuploidy)Having a missing chromosome (aneuploidy)Having 2 whole sets of chromosomes (polyploidy)Having NO chromosomes (zygote is unlikely to form in this case)

Offspring formed from gametes with the incorrect number or chromosomes can end up having:3 or more of an individual chromosome aneuploidy3 or more sets of chromosomes polyploidy

Polyploidy generally only occurs in plants and can be advantageous as often results in bigger better crops, or seedless crops (infertile plants have no seeds!)

Aneuploidy in the sex chromosome in humans can result in:Turners Syndrome XOKlinfelters Syndrome XXY

Aneuploidy in an autosomal chromosome in humans can result in:Downs Syndrome trisomy 21 3 number 21 chromosomeEdwards Syndrome trisomy 18 3 number 18 chromosomes

Types of PolyploidyPolyploidy can result in both sterile and fertile offspring

In order to be fertile an organism needs to have an EVEN number of chromosomes (so they can line up in homologous pairs and separate during meiosis

Autopolyploids organisms with multiple sets of chromosomes from the SAME species

Allopolyploids organisms with multiple sets of chromosomes from DIFFERENT species

Auto polyploidyEg a potato produces gametes with polyploidy (more than one set of chromosomes) and mates with another potato giving rise to a new potato with autopolyploidy (3 sets of chromosomes but all from the potato family, and likely to be sterile as uneven number of chromosomes)Often occurs when plants self fertilize

If both gametes have undergone non disjunction then the offspring will be fertile as it will be have an even number of chromosomes -4n or tetraploid, happens when plants self fertilizeIf only one gamete has undergone non disjunction it will result in infertile offspring as there will be an uneven number of chromosomes 3n or triploid

Polyploidyhttps://cienciascondgerman.wikispaces.com/file/view/Poliploidia.swf

AllopolyploidyEg a wheat plant fertilizes a rye plant If the offspring has an uneven number of chromosomes due to non disjunction having occurred in one of the gametes then the offspring will be infertileIf the offspring has an even number of chromosomes due to non disjunction occurring in both gametes then the offspring will be fertileIf the uneven numbered gamete manages to fuse with another normal gamete and a plant with even chromosomes arises then it will be a fertile hybrid this usual occurs as a result of self fertilisation. Hybrid made from two different species

TasksComplete workbook pages 161-163 and 182-184

Isolating MechanismsIn order for a new species to arise it must not be able to reproduce with the parent species.Prevention of reproduction can occur in several ways:

1. Pre Zygotic (before a zygote is formed)Geographical separated by space, river, ocean, mountain, road etcTemporal reproducing at different times of year, active at different times of dayEcological live in different ecological niches Behavioural different courtship behavioursStructural barriers reproductive genitalia incompatibleGamete incompatibility pollen grains dont grow pollen tubes

2. Post Zygotic (once zygote has formed)Polyploidy multiple sets of chromosomes, in an uneven number so that offspring are infertile

Hybrid Inviability zygote is aborted as has chromosomal incompatibility

Hybrid Sterility off spring survives but is sterile mule

Hybrid breakdown hybrid is fertile but its offspring are sterile

TasksComplete workbook pages 173-178

Complete workbook pages 190-198

Complete Isolating Mechanisms Jigsaw Worksheet

Complete Moodle Quiz Isolating Mechanismshttp://learningon.theloop.school.nz/moodle/mod/quiz/view.php?id=68829Complete the following online Activities:http://ats.doit.wisc.edu/biology/ev/sp/t2_a.htm

Kahoots Isolating Reproductionhttps://play.kahoot.it/#/?quizId=18bcd549-da76-465e-b365-74c9b13239f9

EvolutionEvolution - the gradual change in species over long periods of time resulting in establishment of a new species, (lots of speciation's occurring one after the other over millions of years!)

Variation of alleles exists within the population

The organisms are exposed to a selective pressure such as a changing environment

Those with favorable phenotypes are more likely to survive and reproduce while those with less favorable phenotypes have less chance of surviving and reproducing. survival of the fittest

Each generation will be better adapted to the current environment.

Patterns of EvolutionSpeciation or evolution can occur in a variety of ways:Divergence (A)Common ancestor, but no longer look the sameHumans and apes from a common primate ancestor

Convergence (B)Unrelated ancestor, but look similar due to similar selction pressures due to living in similar environmentWhales and fish look the same as both live in water but NOT related

Parallel Evolution (C)Unrelated ancestor, dissimilar environment but still look similarAdaptive radiation

Co-evolutionSpecies which are unrelated but have a close ecological relationship exert selection pressures on each otherPredator /prey eg flowers grow to allow certain birds to pollinate, birds develop long beaks so can get pollen

TasksComplete worksheets cut and paste match, Patterns of Evolution - Divergence

Read Pathfinder pages 18-22, answer questions 1-9 (these are similar to what you will get in the exam!)

Read pathfinder pages 25-28, complete questions 1-6

Complete Moodle Quiz Patterns of Evolutionhttp://learningon.theloop.school.nz/moodle/mod/quiz/view.php?id=68842

Complete the following online activities:http://ats.doit.wisc.edu/biology/ev/sp/t3_a1_a.htmhttp://ats.doit.wisc.edu/biology/ev/sp/t3_a1_c.htm

Rate of Evolutionary ChangeGradualismSlow progressive change over time

Punctuated equilibriumGenerally slow change but with periods of rapid evolution Caused by rapid and extreme changes to the environmentEg ice age, volcanic eruptionComplete workbook pages 184-190

Evidence for EvolutionFossils comparison to current day species

Comparative Anatomy

Homologous structures Same origins but different functionForelimb bones of birds, humans, whales, bats

Analogous structuresDifferent origins but similar functionsWings of bats, birds, and moths

EmbryologyThe more similar embryos are of different species the less time has past since they divergedBio geographical geographical origins of current species distributionsBiochemical similarities between DNA and proteins

Complete workbook pages 153-160

TasksRead Pathfinder pages pages 18-22, answer questions 1-9 (these are similar to what you will get in the exam!)Read pages 25-28

Complete Evidence for Evolution Jigsaw worksheet

Complete Moodle Quiz Evidence for Evolutionhttp://learningon.theloop.school.nz/moodle/mod/quiz/view.php?id=68848

Complete Evolution NZ Examples worksheetshttps://play.kahoot.it/#/?quizId=8e8173c1-cde2-4238-8de3-dc2651e875f4https://play.kahoot.it/#/?quizId=51375569-7666-4ac2-b57b-6c6dd5da647fhttps://play.kahoot.it/#/?quizId=e74b4ec1-9155-4ca2-82b4-a6da4f291982https://play.kahoot.it/#/?quizId=f3d74de6-5ae6-4480-8aec-cafc1224ce84

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