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Evolutionary Processes
Workbook 5
Year 13 Science
2016
Patterns of evolution
The fossil record
demonstrates
macroevolution as
structural changes in
hard body parts are
seen.
The fossil record
shows
transitional forms
in whale
evolution.
To show
relationships
taxonomists arrange
organisms into
phylogenetic trees
based on their
primitive and more
specialised structural
characteristics.
1. What does the
original walking
front limb evolve
into?
Flipper
Recently DNA
evidence has
become important.
Rate of Change – gradualism and punctuated equilibrium
In species selection, the species that survive the longest in evolutionary history:


produce most new species
have the greatest effect on a pattern
If environmental conditions change, the trend may reverse or stop - as macroevolution takes place,
new groups of species arise, change and become extinct over time.
Evolution proceeds by gradualism, punctuated equilibrium, or a combination of both.
In gradualism, there is a slow, constant rate of change in species over time in response to various
selection pressures – as shown by transitional forms in the fossil record.
In punctuated equilibrium, there may be very long periods of stasis, perhaps brought about by
stabilising selection, where there is hardly any evolutionary change for millions of years, followed by
short burst of rapid speciation. This often involved the formation of many different species that are
no longer closely related. There are few transitional fossils because of the rapid pace of change.
2.
Which evolutionary tree shows slow, continual change?
gradualism
3.
Which evolutionary tree shows periods of rapid change?
punctuated equilibrium
4.
Name the pattern of evolution for each of the following situations.
a.
The tiny foraminiferan plankton Globotalia, found in New Zealand waters, had a compressed
shell and a keel 7 million years ago. The plankton microfossil record shows the many tiny
changes towards the modern form, which has a rounded shell with no keel. gradualism
b.
gradualism
c.
A punctuated
B gradualism
d.
d. punctuated
5.
a.
b.
c.
d.
Write a definition for each of the key words in the table - in your own words
Keyword
gradualism
punctuated
equilibrium
phylogenetic
tree
stasis
Definition
slow, constant rate of change in species over time in response to various
selection pressures
very long periods of stasis, followed by short burst of rapid speciation
branching diagram that shows evolutionary change
hardly any evolutionary change for a long time
6. Does the evolutionary tree shown
support a model of gradualism or a model
of punctuated equilibrium? Explain your
answer.
Model of punctuated equilibrium
Periods of no change and then periods of
change
Divergent and Convergent Evolution
Divergent evolution is the diversification of a single common ancestral species into two or more
species.
In convergent evolution, species have different ancestral starting points, but they evolve similar
adaptations because they occupy similar ecological niches.
Parallel evolution occurs when species that share a common ancestor but are not closely related
evolve in a similar way independently of each other.
Adaptive radiation is a burst of divergent evolution in which a number of related species diverge
from a common ancestor to fill a variety of different ecological niches, often in different
geographical areas.
An ecological niche is the role that members of a species fill within their biological community e.g.
nocturnal carnivorous birds,
Each new species in adaptive radiation occupies its own niche, separated from the other species by
reproductive isolating mechanisms.
7.
a.
b.
c.
d.
e.
Write a definition for each of the key words in the table - in your own words
Keyword
divergent
evolution
convergent
evolution
parallel
evolution
adaptive
radiation
ecological
niche
Definition
diversification of a single common ancestral species into two or more
species.
species have different ancestral starting points, but they evolve similar
adaptations because they occupy similar ecological niches
species that share a common ancestor but are not closely related evolve
in a similar way independently of each other
burst of divergent evolution in which a number of related species
diverge from a common ancestor t
the role that members of a species fill within their biological community
8.
What happens in the period of stasis?
there is no change
9.
What event demonstrates adaptive radiation?
species 2 changes into 3 and 4
10.
Is there any demonstration of convergent evolution?
no
11.
Is there any demonstration of divergent evolution?
yes
12.
Name the pattern of evolution for each of the following situations.
a.
At least 10 moa species evolved from a single moa ancestor, which lived about 30 mya.
Some moa were very small (29 kg) and others were much larger (250 kg). They occupied
habitats from the coast to alpine areas.
divergent evolution
b.
Organs that have the same function because of similar selections pressures, but have
different structures are analogous organs e.g. wings of insects and birds. They do not have a
common ancestor but have the same function.
convergent evolution
c.
Homologous organs have similar origin and structure e.g. wings on reptiles, bats, birds –
similar bone structure and evolved from a common ancestor. divergent evolution
d.
Hebes are endemic New Zealand plants growing from the coast to high alpine environments.
They have evolved from a low-growing ancestral population that arrived from the northern
hemisphere. There are now more than 120 species that live in distinct habitats. Leaves are
larger where conditions are mild, and smaller in cold dry conditions. There were two bursts
of adaptive radiation.
divergent evolution
13.
There is debate over whether over whether ratites (a group of flightless birds) lost their
ability to fly, or could never fly. One idea is that ratites shared a common flightless ancestor.
They then dispersed and evolved in geographic isolation, so that modern ratites (emu, kiwi,
ostrich) are all very different from one another. However, a researcher in America has
suggested each species became unable to fly after evolving from ancestors that could fly.
a.
What pattern of evolution would ratites show if they had developed over a long time from a
common flightless ancestral species?
divergent evolution
b.
What evolutionary pattern is suggested if ratite species each evolved from an ancestor that
could fly?
parallel
14.
Seabirds such as albatross, mollymawk,
titi and petrel make up at least half the
native bird species in New Zealand.
The diagram opposite shows the
relationship between five main groups of
albatross.
a.
Name the evolutionary pattern illustrated in the albatross group.
divergent evolution
b.
One major characteristic of the albatross group is the amount of time they spend out at sea,
- are many hundreds of different sea birds alive today.
i.
Suggest a factor that could have produced different ecological niches in the marine
environment.
different ecological niches occur because of physical factors – sea temperature, storms,
and the way the birds have adapted to the biological factors – food supply, predators
ii.
Suggest a factor that could have prevented gene flow, allowing speciation to occur
in the albatross.
gene flow may be prevented because breeding usually occurs on land – different mating
and breeding places may be geographically isolated (islands) enabling populations to
evolve allopatrically - also times of breeding may be different (temporal)
15.
Early taxonomists classified the riroriro (New Zealand grey warbler) into the same family as
warblers in the Northern Hemisphere, because of similarities in their beak shape and feeding
behaviour. After DNA analysis, the New Zealand grey warbler has been reclassified into a
genetically unrelated group,.
a.
Give the term that describes two genetically unrelated groups that over time evolve similar
adaptations.
convergent evolution
b.
Give a reason why the New Zealand grey warbler and the Northern Hemisphere warbler,
although genetically unrelated, have evolved similar adaptation for feeding.
similar evolutionary pressures / same natural selection – similar requirements for food,
type of food, and other niche requirements
both forms had structurally similar forms to begin with
16.
New Zealand’s bird species became adapted to a range of habitats. The curved-beak wren
(now extinct) had a long curved beak adapted to extracting grubs from crevices in tree
trunks. Other bird species, such as the wood creepers in South America and some tree
creepers in Australia, have similar beaks to the curved-beaked wren, they also feed by
probing cracks in tree trunks.
Explain how these unrelated species could have evolved their physical similarities.
these birds have unrelated ancestors but have evolved similar adaptations because they
occupy similar niches – this is called convergent evolution
birds have evolved to resemble each other
each bird feeds by extracting grubs from cracks in tree trunks – each has evolved a long
curved beak suited for this method of feeding – beak adapted to this niche
17.
Beside each of the following, write whether the structures are homologous or analogous.
a.
bird wing and human arm
homologous
b.
lungs of mammals and trachea (air tubes) of insects
analogous
c.
bat wing and butterfly wing
analogous
d.
fantail’s eye and cow’s eye
homologous
18.
Write either true or false alongside each of the following statements.
If the statement is false, write the statement correctly.
a.
The wing of a bee is homologous to the wing of a finch.
analogous
b.
Convergent evolution can result in ecological equivalents.
true
c.
Punctuated equilibrium is a theory than can account for the lack of transitional forms in the
fossil record.
true
d.
Species undergoing convergent evolution occupy similar ecological niches.
true
e.
Worldwide, areas with similar climates have similar plant communities, but the plants are
from very different taxa (phylogenetic groups). The similarities result from parallel
evolution.
convergent
19.
The two species of Howea palm on Lord Howe Island evolved there from a common ancestor
between one and two million years ago. Scientists have found that the two Howea species
grow in the same area.
a.
Identify the pattern of evolution that could give rise to these two palm species.
divergent evolution
b.
Identify the type of speciation that is most likely to have occurred in Howea palms.
sympatric speciation - does not involve geographic barrier
c.
Palms are wind pollinated flowering plants. Explain how wind pollination could be related to
the two Howea species being reproductively isolated.
could release pollen at different times , so pollen from one species would not be available
to pollinate the other – temporal isolation
20.
Seals and penguins both have flippers and streamlined bodies for swimming.
Name and describe the pattern of evolution that this shows, and using the examples above, explain
how this type of evolution can occur.
pattern of evolution is convergent
seals and penguins are not closely related but have evolved to live in the same
environment so are subject to similar selection pressures
these pressures have resulted in both species evolving steamlined bodies which facilitate
movement through the water
flippers – from forelimbs in seals
flippers – from wings in penguins
both types of flippers are analogous structures needed to move the body through the
water
Co-evolution is reciprocal evolutionary change – a change in the trait of one species acts as a
selection pressure for a change in a trait of another unrelated species.
Example:
An evolutionary change in the structure of a plant might act as a selection pressure
to bring about a change in a herbivore that eats the plant. This change in the herbivore then acts as
a selection pressure for a change in the structure in the plant to reduce herbivory.
Co-evolution is more likely when different species interact with one another.





predator and prey
parasite and host
species that compete for food, shelter, nesting sites
species that have a mutualistic (symbiotic) relationship
pollinators and flowering plants
21.
Snapdragon plants have evolved flowers whose shape and colour make them attractive to
bumblebees. The bees have evolved sense organs and mouthparts that enable them to find and
extract pollen from snapdragon flowers. Suggest how the snapdragon and bumblebee might have
evolved.
both may be the product of co-evolution
snapdragon plant developed flowers that were visited by bumblebees – this resulted in pollination
and produced more plants with similar flowers
those bumblebees with mouthparts and sense organs best suited for extracting pollen from
snapdragons were selected for in areas where bumblebees and snapdragons were both present
if a change in snapdragon flowers occurred, there would be strong selection pressures for
bumblebees to change
22.
Leapard seals are a predator of Antartic species of penguin. It is possible that these seals
and penguins may have co-evolved. Explain how co-evolution may have occurred in this example.
leopard seals are predators of penguins – any feature of the seal that improves its success as a
predator makes it more likely to survive and breed and pass on successful alleles
greater predatory success of the seals acts as selection pressure on penguins – penguins that
reduce the predatory success of seals are more likely to survive and pass on their successful alleles
onto their offspring – these alleles will increase in frequency in the gene pool
these changes act as selection pressures on the seals – and so on – penguins and seals are coevolving