NCEA Level 3

2. Speciation
300 BIOLOGY
GB
2014

3. Introduction
 Complete 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

5. Achievement Standard
Evolutionary processes involve the following biological ideas:
 Role of mutation
 Gene flow
 Role of natural selection and genetic drift
 Modes 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 Zealand’s flora and
fauna, will be selected from:
 fossil evidence
 Comparative anatomy (homologous and analogous structures)
 Molecular biology (proteins and DNA analysis)
 Biogeography.

7. The Basics
Terms:
 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.

8. Changes in Allele Frequencies
 Bottleneck 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

12. Tasks
 Complete workbook pages 171-173
 Complete Worksheet: Gene Frequency
Questions
 Complete Gene Pools Moodle Quiz
http://learningon.theloop.school.nz/moodl
e/mod/quiz/view.php?id=68828
 Kahoots Genetic Drift Basics
https://play.kahoot.it/#/?quizId=a4f952ba-
9dcb-4995-a247-75d30a8af5d8

13. Natural Selection
Organisms 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

15. Variation
 Differences 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.

16. Cline Speciation
 Cline 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

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

19. Speciation
 One 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

21. Speciation
There are three ways in which new
species can evolve:
1. Instant Speciation
 Occurs within one generation as
a result of polyploidy
 more than two sets of
chromosomes
 Usually occurs in plants

22. Speciation
2. Sympatric Speciation
 Occurs when a new species arises in the SAME
territory as the parent species
 Often occurs as a result of niche differentiation
(ie finches living in top of trees vs forest floor)
3. Allopatric Speciation
 Occurs when a new species evolves as a result
of being isolated from the parent species
 NEW territory
 Often occurs when there is some kind of
geographical or environmental disturbance

24. 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

25. Polyploidy and Aneuploidy
 Poly – 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

26. Non Disjunction
 Non 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)

29.  Offspring formed from gametes with the incorrect number or chromosomes
can end up having:
 3 or more of an individual chromosome – aneuploidy
 3 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!)

30.  Aneuploidy in the sex chromosome in
humans can result in:
Turners Syndrome – XO
Klinfelters Syndrome – XXY
 Aneuploidy in an autosomal
chromosome in humans can result in:
Downs Syndrome – trisomy 21 – 3 number
21 chromosome
Edwards Syndrome – trisomy 18 – 3
number 18 chromosomes

31. Types of Polyploidy
 Polyploidy 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

33. Auto polyploidy
 Eg 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 fertilize
 If 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

34. Polyploidy
 https://cienciascondgerman.wikispaces.com/file/view/Poliploidia.swf

36. Allopolyploidy
 Eg 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 infertile
 If the offspring has an even number of chromosomes due to non disjunction occurring in both gametes
then the offspring will be fertile
 If 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

39. Tasks
 Complete workbook pages 161-163 and 182-184

40. Isolating Mechanisms
 In 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 etc
 Temporal –reproducing at different times of year, active at different times of day
 Ecological – live in different ecological niches
 Behavioural – different courtship behaviours
 Structural barriers – reproductive genitalia incompatible
 Gamete incompatibility – pollen grains don’t grow pollen tubes

43. 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

44. Tasks
 Complete workbook pages 173-178
 Complete workbook pages 190-198
 Complete Isolating Mechanisms Jigsaw Worksheet
 Complete Moodle Quiz Isolating Mechanisms
http://learningon.theloop.school.nz/moodle/mod/quiz/view.php?id=68829
 Complete the following online Activities:
http://ats.doit.wisc.edu/biology/ev/sp/t2_a.htm
 Kahoots Isolating Reproduction
https://play.kahoot.it/#/?quizId=18bcd549-da76-465e-b365-74c9b13239f9

46. Evolution
 Evolution - 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.

47. Patterns of Evolution
Speciation or evolution can occur in a variety of ways:
 Divergence (A)
 Common ancestor, but no longer look the same
 Humans and apes from a common primate ancestor
 Convergence (B)
 Unrelated ancestor, but look similar due to similar selction pressures due to living in similar environment
 Whales and fish look the same as both live in water but NOT related
 Parallel Evolution (C)
 Unrelated ancestor, dissimilar environment but still look similar
 Adaptive radiation
 Co-evolution
 Species which are unrelated but have a close ecological relationship exert selection pressures on each other
 Predator /prey eg flowers grow to allow certain birds to pollinate, birds develop long beaks so can get pollen

48. Tasks
 Complete 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 Evolution
http://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.htm
http://ats.doit.wisc.edu/biology/ev/sp/t3_a1_c.htm

50. Rate of Evolutionary Change
 Gradualism
 Slow progressive change over time
 Punctuated equilibrium
 Generally slow change but with periods of rapid
evolution
 Caused by rapid and extreme changes to the
environment
 Eg ice age, volcanic eruption
 Complete workbook pages 184-190

52. Evidence for Evolution
 Fossils – comparison to current day species
 Comparative Anatomy
 Homologous structures
 Same origins but different function
 Forelimb bones of birds, humans, whales, bats
 Analogous structures
 Different origins but similar functions
 Wings of bats, birds, and moths

53.  Embryology
 The more similar embryos are of different species the less time has past
since they diverged
 Bio geographical – geographical origins of current species
distributions
 Biochemical – similarities between DNA and proteins
 Complete workbook pages 153-160

54. Tasks
 Read 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 Evolution
http://learningon.theloop.school.nz/moodle/mod/quiz/view.php?id=68848
 Complete Evolution NZ Examples worksheets
 https://play.kahoot.it/#/?quizId=8e8173c1-cde2-4238-8de3-dc2651e875f4
 https://play.kahoot.it/#/?quizId=51375569-7666-4ac2-b57b-6c6dd5da647f
 https://play.kahoot.it/#/?quizId=e74b4ec1-9155-4ca2-82b4-a6da4f291982
 https://play.kahoot.it/#/?quizId=f3d74de6-5ae6-4480-8aec-cafc1224ce84

55. The End