Post on 03-Feb-2022
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Wildflower population: Genetic drift1
Figure 1: Field of tulips (Image: Sakurai Midori, Source:
http://upload.wikimedia.org/wikipedia/commons/thumb/a/a2/Lily_flowered_tulip.jpg/800px-Lily_flowered_tulip.jpg)
There are 40 plants of one species on a meadow. They differ only in the colour of their flower (which
is inherited): there are 10 red flowers, 10 white flowers, 10 green flowers and 10 blue ones. A blind
snail that also lives on the meadow eats one plant a day, not preferring plants with a specific
coloured flower. Every time a plant has been eaten, another one is able to reproduce itself (by
producing a stolon, for example) and occupies the free space.
Tasks:
1a) Tick your hypothesis for the development of the population:
o There will be a major change in the composition of the population.
o The proportions of the flower colors will always range around 25%.
1 Game based on: Scheersoi, A. & Kullmann,H. 2007. さGWミSヴキaデ ┌ミS “WノWニデキラミ ゲヮキWノWヴキゲIエ ┗WヴマキデデWノミくさ Praxis der
Naturwissenschaften-Biologie in der Schule 7: 45-47.
Material: wooden beads, bag, petri dishes
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1b) Simulate the development of the population by following the game instructions. After each
turn, write down the composition of the population in Table 1.
1c) Tick how the wildflower population has evolved.
o There has been a major change in the composition of the wildflower population on account
of the snail.
o The proportions of the flower colors have always ranged around 25%.
1d) Note the assumptions of the model about the influence of evolutionary factors on the
wildflower population.
Game Instructions:
Put 10 beads of each colour (10 red ones, 10 white
ones, 10 green ones and 10 blue ones) in the bag.
They represent the different coloured flowers. Draw
one bead from the bag and put it in the petri dish. A
plant of this colour is eaten by the blind snail. Draw
a second bead, representing the flower which can
reproduce itself. Therefore you have to add a
second bead of this colour and put both of them
back in the bag. The number of beads in the bag
should be 40 after each move. Write the amount of
W;Iエ Iラノラ┌ヴ Sラ┘ミく Nラ┘ キデ キゲ デエW ミW┝デ ヮノ;┞Wヴげゲ デ┌ヴミく When you have finished, you should analyse how
the population has developed.
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1e) Optional task: Explain how you would change the game if the beads did not represent
different flower colours but different alleles.
Vocabulary list
English German
allele Allel
bead Perle
composition Zusammensetzung
evolve (from sth.) sich (aus etwas) entwickeln
flower Blüte
Genetic Drift Gendrift
meadow Wiese
petri dish Petrischale
proportion Anteil
range schwanken
reproduce sich fortpflanzen
stolon Ausläufer
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Table 1: Development of the wildflower population
number of
turns/days
number of flowers
red white blue green
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
number of
turns/days
number of flowers
red white blue green
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
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Cabbage: Artificial Selection
Several vegetables have been produced from the wild cabbage as a result of artificial selection
(domestication) that has begun about 2000 years ago. Today, kale, Brussels sprouts, broccoli,
kohlrabi, head of cabbage and cauliflower, amongst others, belong to its most popular cultivated
forms.
German English
Wildkohl wild cabbage
Grünkohl kale
Kopfkohl head of cabbage
Rosenkohl Brussels sprouts
Kohlrabi kohlrabi
Blumenkohl cauliflower
Brokkoli broccoli
German English
Endknospe terminal bud
Blütenstand peduncle
Blatt leaf
Hauptachse main axis
Seitenknospe lateral bud
Material: wild cabbage, kale, head of cabbage, Brussels sprouts, kohlrabi, cauliflower, broccoli, scissors
Figure 1: Vegetables derived from the wild cabbage (Saedler,
HWキミ┣く ヲヰヱヲく さ“WノWニデキラミくざWiS Begierig 4: 14.)
Figure 2: Plant organs in 1st
and 2nd
year (Saedler, Heinz.
ヲヰヱヲく さ“WノWニデキラミくざWiS Begierig 4: 11)
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Tasks:
1) Compare the different vegetables (Fig. 1) to the wild cabbage. Find out for each vegetable which
organ (Fig. 2) differs most from the wild cabbage and how. You may use scissors to cut parts of the
plants off to examine them. Write down your results by putting the terms below to the right place
in Table 1.
enlarged (x2)
thickened
transformed (x2)
crimped
Table 1: Which selection has led to which vegetable?
vegetable\ organ
1st
year 2nd
year
terminal bud main axis leaf peduncle lateral bud
kale
head of cabbage
kohlrabi
Brussels sprouts
cauliflower
broccoli
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Vocabulary list
English German
artificial selection künstliche Selektion
broccoli Brokkoli
Brussels sprouts Rosenkohl
cauliflower Blumenkohl
crimped gekräuselt
cultivated bebaut, kultiviert
domestication Domestikation
enlarged vergrößert
head of cabbage Kopfkohl
kale Grünkohl
kohlrabi Kohlrabi
lateral bud Seitenknospe
leaf Blatt
main axis Hauptachse
peduncle Blütenstand
scissors Schere
terminal bud Endknospe
thickened verdickt
transformed umgewandelt
wild cabbage Wildkohl
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Cacti: Natural Selection
Most cacti live on the American continent, in extremely dry environments like deserts. Since water is
scarce there, their habitat poses a challenge to them. They show several adaptednesses to drought.
Tasks:
1) How might the visible traits of cacti contribute to efficient water use? Examine the cacti
and assign the functions below to the adaptednesses listed in Table 1.
reduction of transpiration rate (x2)
protection from herbivores
provide shade (x2)
store water
photosynthesis
Table 1: Adaptednesses of cacti and their functions
adaptedness
functions of the structure
thick stems with cylindrical or spherical
shape (low surface area-to-volume ratio)
thick waxy coverings (cuticles)
ribs
green stems
modified leaves: spines
Material: cacti
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2) Put the statements below (a-e) in the right order to describe how the adaptation of the stem
shapes of cacti has occurred over a long period of time.
a. Plants with a rather spherical shape were more likely to survive and reproduce themselves
because they lost less water through transpiration. They had a greater relative fitness.
b. Originally, the individuals of the plant population had a non-spherical shape.
c. The frequencies of alleles for a spherical shape increased in the gene pool of the next
generations.
d. On account of further mutations and/or recombination, individuals with an even more
spherical shape appeared which lost even less water.
e. Plants with a rather spherical shape resulted from mutations.
3) Discuss in your group the different meanings of the terms adaptation and adaptedness in
the sentences a. and b. below. Try to come up with a short definition for both terms.
a. The adaptation of the stem shapes of cacti to the drought occurred over many generations.
b. The spherical shape of cacti stems is an adaptedness to drought.
Adaptation is
Adaptedness is
Figure 1: Barrel cactus (Source: http://www.garden-
services.com/gallery/cacti/images/cactusbarrel.jpg)
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Vocabulary list
English German
adaptation Anpassung
adaptedness Angepasstheit
cactus, pl.:cacti/cactuses Kaktus, pl.: Kakteen
cuticle Cutikula
cylindrical zylindrisch
drought Trockenheit
gene pool Genpool
herbivore Pflanzenfresser
surface area-to-volume ratio Oberfläche-zu-Volumen-Verhältnis
natural selection natürliche Selektion
photosynthesis Photosynthese
relative fitness Darwin-Fitness, evolutionäre Fitness
rib Rippe
scarce knapp
shade Schatten
spherical kugelförmig
spine Dorn
transpiration rate Transpirationsrate
waxy wachsartig
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Maize: Recombination
Chance events like mutation and sexual recombination are sources of genetic variation in the gene
pool of a population. They are also responsible for the great diversity of maize. Every grain of a maize
ear is produced from an individual fertilization. Thus, hundreds of offspring can be analysed on a
single ear. The phenotypes that will be studied in the following activity on interchromosomal
recombination (i.e. the assortment of chromosomes of the parents to the gametes) are the grain
colour and grain texture.
Tasks:
1a) The maize ears at hand are the F2 generation which results from the cross between a plant
homozygous for purple (R/R) and smooth (Su/Su) grains and a plant homozygous for yellow
(r/r) and wrinkled (su/su) grains. Assign the phenotypes to the genotypes in Table 1 by using
crayons: Indicate wrinkled grains by stripes and smooth grains by colouring the whole field
using a yellow (for yellow grains) or purple (for purple grains) crayon. Remember: Capital
letters indicate dominant alleles.
P: R/R Su/Su x r/r su/su
F1: R/r Su/su
F1 Cross: R/r Su/su x R/r Su/su
Table 1: Gametes of the F1 generation and genotypes of the F2 generation
F2:
gametes
R Su R su r Su r su
R Su
R/R Su/Su R/R Su/su R/r Su/Su R/r Su/su
R su
R/R Su/su R/R su/su R/r Su/su R/r su/su
r Su
R/r Su/Su R/r Su/su r/r Su/Su r/r Su/su
r su
R/r Su/su R/r su/su r/r Su/su r/r su/su
Material: maize ears of F2 generation from the heredity below, yellow
and purple crayons
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1b) State in which proportion you expect the phenotypes of the maize ear at hand.
1c) Count the grains of each phenotype. Calculate the total number of grains and the total of
each phenotype and record them in Table 1. Check if the numbers for each phenotype
correspond to the numbers you would have expected according to 1b).
Table 2: Numbers for each phenotype of grains
phenotype class purple,
smooth
purple,
wrinkled
yellow,
smooth
yellow,
wrinkled
total number
of grains
ear 1
ear 2
ear 3
total number for each phenotype
expected number for each phenotype
2) Optional task: How many possible combinations of interchromosomal recombination, i.e.
how many different gametes are there for maize with n= 10 chromosomes? Enter the outcome:
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Vocabulary list
English German
allele Allel
assortment Mischung
crayon Buntstift
diversity Vielfalt
fertilization Befruchtung
gamete Gamet/Keimzelle
gene pool Genpool
genetic variation genetische Variation
grain of maize Maiskorn
interchromosomal
recombination
interchromosomale
Rekombination
maize Mais
maize ear Maiskolben
offspring Nachkommenschaft
phenotype Phänotyp
population Population
proportion Anteil
recombination Rekombination
smooth glatt
wrinkled runzelig
purple violett
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Maize-Darts: Mutation
Chance events like mutation and sexual recombination are sources of genetic
variation in the gene pool of a population. They are also responsible for the
great diversity of maize. The indigenous peoples of the Americas domesticated
the wild crop relative Teosinte (Fig. 1) to maize. Although these two plants look
very different from each other, some of the major changes are due to only one
mutated gene each. As the natives had opened up of the new food source
maize, they could spend more time for cultural activities: civilizations of the
Americas known for their cultural achievements like the Maya came into being.
Tasks:
1a) The picture on the dartboard (Fig. 2) shows the maize
genome with its 10 chromosomes in a gamete. It is retraced
from the photo of an electron microscope. Step behind the
line on the floor, put the blindfold on so that you cannot
see anything and throw the darts at the dartboard (at
least 15 times). Write down in Table 1 how often you
threw the darts and how often you hit a chromosome.
Figure 1: Wild crop relative Teosinte ( Saedler,
Heinz. 2011 く さM;キゲ-DラマWゲデキニ;デキラミくざ WiS
Begierig: 7)
Material: dartboard with picture of maize genome, darts
More on the diversity of Maize: transposable elements
The great diversity of Maize results from the fact that its genome contains 85%
transposable elements which are responsible for 80% of spontaneous
mutations. Transposable elements are genes or parts of genes which can change
their position within the genome of a cell. They can either be copied
(retrotransposons) or cut out (DNA transposons) and pasted to a different
position. Their activity may lead to new sequences. Transposable elements are
pervasive in multi-cellular organisms.
Figure 2: Genome in a gamete of maize (modified
after Saedler, Heinz. 2012. WiS Begierig 4: 15)
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1b) Rates of spontaneous mutations in organisms range from 10-6 to 10-5 per gene and
generation. That means that only one cell of 1.000.000 to one of 100.000 cells have a mutation in
the considered gene. Most mutations can be repaired by mechanisms of the cell. If every throw
targeted another gamete of one generation, what would be the rate of spontaneous mutations
in Maize? Add the throws and hits of your group and gross up to 100.000 throws in Table 1.
Table 1: Darts results
1c) Name the characteristics of mutations which are represented by the dartboard model.
1d) Which characteristic of the genome is not considered in the dartboard model?
1e) Why is it important for evolution that the mutation occurs in the gamete?
Give reasons.
pupil 1 pupil 2 pupil 3 total
hits
throws
total hits per throws
hits per 100.000 throws
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Vocabulary list
English German
blindfold Augenbinde
crop Anbaupflanzen,pl.
dartboard Dartscheibe
dart Dartpfeil
diversity Vielfalt
DNA transposon DNA-Transposon
electron microscope Elektronenmikroskop
gamete Gamet, Keimzelle
genetic variation genetische Variabilität
gross up hochrechnen
hit Treffer
indigenous einheimisch
maize Mais
multi-cellular vielzellig
mutation Mutation
pervasive überall vorhanden
retrotransposon Retrotransposon
throw Wurf
transposable element Transposon
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Neolithic Revolution
About 12.000 years ago, people began to
cultivate plants in the region of the Fertile
Crescent (in parts of what today is Lebanon,
Syria, Turkey, Iraq, Iran, Jordan and Israel)
(Fig. 1). Thereby they laid the foundation
for the Neolithic Revolution.
Task:
1. Use the internet to find out about the Neolithic Revolution. Describe shortly what
the Neolithic Revolution was and how it affected human societies. You may use
ラミW ラa デエW ノキミニゲ HWノラ┘ ラヴ ┌ゲW ニW┞┘ラヴSゲ ノキニW さNWラノキデエキI RW┗ラノ┌デキラミざが さNWラノキデエキI Eヴ;ざが さNWラノキデエキI AェWざ aラヴ ┞ラ┌ヴ ケ┌Wゲデく
http://www.h2g2.com/approved_entry/A2054675
http://www.smm.org/catal/mysteries/what_were_they_eating/hunting_and_gathering/
http://history-world.org/agriculture.htm
Neolithic Revolution:
Vocabulary list
English German
fertile crescent Fruchtbarer Halbmond
Neolithic Age/Era Neolithikum
Neolithic Revolution Neolithische Revolution
Figure 1: Region of the Fertile Crescent (Saedler, Heinz. ヲヰヱヱく さA┌a SWマ WWェ ┣┌ヴ HW┝;ヮノラキSキWぎ EママWヴ ┌ミS DキミニWノくざ Wキ“ BWェキWヴキェ ヱ: 9.)
Material: computer with access to the internet
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Wheat: Artificial Selection
At the beginning of the Neolithic Era about 12.000 years ago, harvesting the wheat ancestor Wild
Einkorn was cumbersome as the ripe spikes were very brittle and shattered easily (shattering spikes)
into the single spikelets which contained only one grain each. These grains then had to be collected.
Afterwards, the protective tough glumes which enclosed the grains (hulledness) had to be removed.
These features enabled the spikelets and the grains to disperse. Many years of domestication passed
by until modern day wheat forms like soft and durum wheat have evolved. Their spikes do not
shatter easily (non-shattering spikes) and have light glumes (free-threshing).
Tasks:
1) Time travel: Think back to the time of the Neolithic Era was when agriculture expanded. Your
family is starving and tired from hunting and gathering. One day you meet a traveller from far away.
He sells wheat spikes to you which are different from the ones you know in some respects. He
promises that these spikes would mean an end to your food shortage. However, unfortunately you
have mixed them up with the spikes you already had. Now you have to decide about which grains to
sow and it is up to you to assure the survival ラa ┞ラ┌ヴ a;マキノ┞ぐ
Take the spikes labelled 1 and 2 in your hands and compare them regarding the features in table 1.
Then assign the numbers of the spikes to right blank in the wheat pedigree (Figure 2).
Table 1: features of spikes 1 & 2
Figure 1: Wheat spike (D) and spikelet (E) with lemma (d), outer glume (h) and palea (v) (modified after Strasburger, E. et al.
2008. Lehrbuch der Botanik. Heidelberg: Spektrum Akademischer Verlag: 867)
English German
palea Vorspelze
lemma Deckspelze
outer glume Hüllspelze
spike Ähre
spikelet Ährchen
spikes grains
shattering non-shattering hulled free-threshing
1
2
Material: spikes labelled 1 and 2
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2) Optional task: Would the modern wheat forms also survive in nature without human
intervention? Give reasons.
Vocabulary list
English German
agriculture Landwirtschaft
allopolyploidy Allopolyploidie
ancestor Vorfahre
artificial selection Künstliche Selektion
brittle brüchig
cumbersome mühsam
(to) cultivate anbauen
(to) disperse sich verteilen, ausbreiten
durum wheat Hartweizen
Emmer Emmer
food-shortage Nahrungsmittelknappheit
free-threshing freidreschend
Goatgrass Gänsefußgras
glume Spelze
grain Getreidekorn
(to) harvest ernten
hulled bespelzt
hybridization Kreuzung
lemma Deckspelze
Neolithic Era Neolithikum
outer glume Hüllspelze
palea Vorspelze
pedigree Stammbaum
polyploidy Polyploidie
ripe reif
shatter zerbrechen
soft wheat Weichweizen
sow aussäen
Spelt Dinkel
spike Ähre
spikelet Ährchen
Wild Einkorn Wildes Einkorn
Wild Emmer Wilder Emmer
Wild Spelt Wilder Spelzweizen
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Figure 1: Wheat pedigree (modified after Saedler, Heinz. ヲヰヱヱく さけFヴWキSヴWゲIエWミSげ キミ SキW Z┌ニ┌ミaデぎ H;ヴデ- ┌ミS WWキIエミ┘Wキ┣Wミくざ WiS Begierig 1: 11)
Durum wheat
Wild
Einkorn
Wild
Spelt
Wild
Emmer Goatgrass
Spelt
Soft Wheat
shattering spikes
non-shattering spikes
hulledness
free-threshing
years BC
Neolithic Era
Extension: Polyploidy
Abnormal cell division during meiosis may lead to organisms containing more than two sets
of chromosomes. Hybridization may result in polyploids with chromosomes from different
species (alloploidy). Polyploidy is common in plants. Hexaploid soft wheat results from
hybridization of a tetraploid wheat form and a diploid wild grass.