BEANZPractice ExaminationLevel 3Biology2014

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BiologyNCEA Level 3

Achievement Standard 91605

B 3.5 Demonstrate understanding of evolutionary processes leading to speciation

Credits: 4Instructions: You should answer ALL the questions in this booklet Check that this booklet has pages 2 to 13 in the correct order and that none of these

pages is blank YOU MUST HAND THIS BOOKLET TO THE SUPERVISOR AT THE END OF THIS

EXAMINATION You are advised to spend 60 minutes answering the questions in this booklet

Achievement Criteria:

Achievement Achievement with Merit Achievement withExcellence

Demonstrate understanding of evolutionary processes leading to speciation.

Demonstrate in-depth understanding of evolutionary processes leading to speciation.

Demonstrate comprehensive understanding of evolutionary processes leading to speciation.

Overall Level of Performance:

2

Question 1 Gene pool changes in some NZ birds

Gene pool changes (changes in gene frequencies) can be the result of genetic drift and / or natural selection

Below are some examples of genetic drift in two NZ birds:

Example 1:The Silvereye or Wax-eye (Zosterops lateralis) is a very small bird found throughout the South-West Pacific.In New Zealand, the Silvereye was first recorded in 1832 after a small number of birds were swept eastwards from Australia by a storm. The original population of this self-introduced bird quickly grew and spread throughout the country.

Waxeye feeding on flax flowerswww.doc.govt.nz

Adult kaki www.doc.govt.nz

Example 2:Kaki (Black Stilts) are the world’s rarest wading bird; they are critically endangered.This is due to habitat destruction and introduced predators.In 1981 the entire species was reduced to only 23 adults. As a result of predator control and a captive breeding programme, with subsequent releases into the wild, the population has now increased. There are now about 80 adult birds.

a. Using the examples above explain the terms founder effect, bottleneck effect and genetic driftIn you answer you should

define each term, describe the relationship between the terms and explain why they occur, the conditions under which they occur and any possible consequences to the population they operate in

use the two examples above to illustrate and explain your answer

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Example 3:New Zealand birds evolved in the absence of predators. Therefore, many lacked the normal fear response and are poor flyers. They are thus extremely vulnerable to introduced predators.A commonly used conservation strategy is to transfer small populations of birds such as the South Island Saddleback to (predator free) offshore islands where populations can breed in relative safety.A total of 36 Saddlebacks have been transferred to 11 different islands and the total population is now over 700 birds.

South island Saddlebackwww.doc.govt.nz

b. When small populations are established on islands, there are genetic consequences for the species as a whole.Describe the effect on the gene pool of the isolated populations.Discuss strategies conservationists could use to ensure any detrimental effects are minimised both when populations are transferred to new islands or later, as the isolated populations increase in size.

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c. When European immigrants first settled New Zealand, a number of bird species were introduced, including chaffinches and goldfinches. These populations were often established from imports of fewer than a dozen birds.Comparisons of these new populations with their parent populations in Europe show that in the New Zealand populations:

o hatching failure due to embryo developmental problems are higher (by up to 10% of eggs)

o rates of parasite infections are higher (by up to 20%)

Now that these species have been in New Zealand for 150 years other changes have also been noted; in particular there have been changes in body size and proportions.

Relate these phenotypic characteristics to genetic drift and natural selection and elaborate on any possible future changes.In your answer you should:

explain how genetic drift has impacted on these populations explain how natural selection has impacted on these

populations discuss how and why changes in phenotype may occur in the

futureChaffinch (above) and goldfinch (below)

both photos www.doc.govt.nz

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Question 2 Polyploidy and hybridization in Pratia

The genus Pratia has about a dozen species native to New Zealand, Australia and Asia. The genus belongs to the Campanulaceae or bellflower family of flowering plants.New Zealand has four endemic species and a number of hybrids. The ancestor of the New Zealand species is thought to have had a chromosome number of 2n = 14. Once established in New Zealand speciation by polyploidy, hybridisation and adaptive radiation has occurred.

Table 1: Distribution and chromosome numbers of New Zealand’s Pratia species.

Pratia species Distribution Chromosome number

P. arenia Chatham islands, South Island 2n = 70

P. macrodonNelson, CanterburyOtago

2n = 142n = 28 (possible new species)

P. perpusilla Auckland, Canterbury 2n = 42

P. angulataNorth and South Islands - widespreadNorth and South Islands - widespread

2n = 702n= 140

Phylogeny of NZ Pratia species (numbers in brackets are chromosome numbers):

ancestor (14

time:

P. angulata (70)

Photo: P. angulata in flower

P. angulata (140)

P. arenia (70)

P. perpusilla (42)

P. macrodon (14)P. macrodon (28)

Hybrids of Pratia species can occur naturally or can be produced by deliberate cross-pollinations (transfer of pollen between flowers of different species).

Table 2: Chromosome numbers and seed viability of selected hybrids

Pratia species Chromosome number Hybrid germination rate

P. angulata (70) X P. angulata (140) 2n = 105 70 – 95 %

P. macrodon (14) X P. macrodon (28) 2n = 21 Nil

P. angulata (70) X P. perpusilla (42) 2n = 562n = 77

30 – 50 %30 %

P. angulata (140) X P. perpusilla (42) 2n =91 50- 80 %

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a. Many of the Pratia species above are polyploids. Discuss the significance of polyploidy in the genus Pratia.

In your answer you should: describe polyploidy explain how polyploid species arise naturally, using the information provided above to

identify possible polyploid species explain if this mechanism of speciation is allopatric or sympatric discuss any Reproductive Isolating Mechanisms (RIM’s) that usually operate between

polyploids and their parent species. Comment on the effectiveness of RIM’s in the genus Pratia using named examples in your answer.

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b. It is known that speciation and adaptive radiation in the Pratia genus is relatively recent. Discuss the significance of these processes.

In your answer you should: define the terms speciation and adaptive radiation explain the mechanism of adaptive radiation and evaluate the conditions required for this

process to occur.

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Question 3 Reproductive Isolating Mechanismsa. Match the examples of Reproductive Isolating Mechanisms in List II with the type of Reproductive

Isolating Mechanism from List I.List I (types) List II (examples)

GeographicA

Lacewing species of the genus Chrysoperla have distinctive songs. Males and females perform duets during courtship that culminate in mating. In some species it has been discovered that there are several forms isolated only by their distinctive songs.

Ecological

BThe synchronised spawning of many Coral species on marine reefs means that inter-species hybridisation is possible as millions of individuals of many different species release gametes simultaneously. However, physiological factors ensure that interspecific zygotes are rarely produced.

Temporal

Behavioural

CSheep-Goat hybrids are occasionally born. Sheep have 54 chromosomes and Goats have 60. Hybrids are known to have 57.Most offspring of these interspecific matings are stillborn and those that are born alive, die soon after birth.

Structural or Mechanical

GameticD

Grizzly bears and Polar bears very rarely produce hybrids. The distributions of the two genetically similar species overlap but whereas Grizzlies live and mate on land, Polar bears prefer water and ice, usually breeding on the ice.Hybrid

Inviability

EMany related related and sympatric plant species like Tradescantia canaliculata and Tradescantia subaspera flower at different times of the year. In these two species, one tends to occupy shady niches where lower temperatures delay flower development.

Hybrid Sterility

Use the letter A to E to fill in the blank column spaces in List 1Not all the spaces will be filled

c. “Speciation could not occur without Reproductive Isolating Mechanisms because they prevent gene flow”. Comment this statement.In your answer, you should:

describe the meanings of the terms gene flow and Reproductive Isolating Mechanism. explain the importance of Reproductive Isolating Mechanisms. You should use examples that

you know other than the ones in the table above to illustrate your answer.

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c. Reproductive Isolating Mechanisms can be grouped in a number of ways.They can be categorised as sympatric or allopatric or alternatively as pre-zygotic and post zygotic.

Compare these various groupingsIn your answer you should:

define sympatric and allopatric. Indicate which Reproductive Isolating mechanisms fall into these two categories

define pre-zygotic and post-zygotic. Indicate which Reproductive Isolating mechanisms fall into these two categories and evaluate the advantages of each in the process of speciation.

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Question 4 Patterns of Evolution

Each of the THREE examples below illustrates a common ‘Pattern’ of Evolution.

Example 1New Zealand Grey WarblerWhen the New Zealand Grey Warbler or Riroriro, was first discovered its similarities to Northern Hemisphere warblers was noted. However, it is an entirely unrelated bird belonging to a different family.The Northern Hemisphere warblers are also small, vocal, forest dwelling insectivores. Because they are dull brown or green colours they are more often seen than heard. The New Zealand bird has similar characteristics, but these do not indicate a common origin.

www.doc.govt.nz

a. Identify and describe the evolutionary pattern described above and explain how it is illustrated by Example 1.

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Example 2New Zealand Wood Pigeon3 species of Wood Pigeons (kereru or kukupa) inhabited New Zealand. All were derived from a common ancestor that dispersed here from Australia or Papua New Guinea. Within New Zealand subsequent dispersal to islands resulted in the three distinct species with different adaptations.Hemiphaga novaeseelandiae on the 3 main islands of NZ, Hemiphaga chathamensis on the Chatham islands to the East and Hemiphaga spadicea (now extinct) on Norfolk Island to the North. www.doc.govt.nz

b. Identify and describe the evolutionary pattern described above and explain how it is illustrated by Example 2.

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Example 3Host-parasite relationshipsThe New Zealand Mud Snail (Potamopyrgus antipodarum) has a number of internal Tremotode parasites (flukes). Long term studies have shown that parasites continually evolve adaptations that help them find and infect new host individuals. The snail is continually evolving mechanisms that help it avoid infection and immune responses to deal with infections should they occur.

http://commons.wikimedia.org/wiki/File:P_antipodarum.jpg

c. Identify and describe the evolutionary pattern described above and explain how it is illustrated by Example 3.

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Parasites and their hosts such as the New Zealand Mud Snail and its internal Trematode parasites, often appear to be in a constant ‘Arms-Race’ where each must evolve and adapt to maintain some advantage over the other. This dynamic is sometimes referred to the Red Queen Hypothesis. It is called this after Alice in Lewis Carroll’s ‘Through the Looking Glass’ declares to the Red Queen:“In this place it takes all the running you can do to keep in the same place”.

Experimental evidence for this hypothesis:This idea has been tested experimentally. In one experiment snails and parasites were collected from different lakes in Westland. Uninfected snails were separately exposed to parasites from both lakes to determine their susceptibility (An Infection Rate of 1.0 indicates that all snails in the group were infected).

Mode of reproduction:The New Zealand Mud Snail can reproduce asexually or sexually. Although individuals do not switch modes of reproduction during their lifetimes, a population usually has a mix of sexually and asexually reproducing individuals.

It is also noted that in the shallow margins of lakes parasite infections are heavier and more individuals will reproduce sexually.In deeper water (over 4 m), parasite infections are rare and individuals mostly reproduce asexually.

Inf

ectio

n R

ates

1.0 Host SourceL1 = Lake 1

0.8 L1 L2 = Lake 20.8

0.6 L20.6

0.4L2

0.2 0.3L1

0.0 0.1L1 L2

Parasite Source

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d. Discuss the apparent ‘Arms Race’ between the New Zealand Mud Snail and its Trematode parasites and the response of the snail, with respect to its changeable mode of reproduction.In your answer you should:

describe what the experimental evidence indicates (what is the overall conclusion) explain if the experiment provides evidence that supports or contradicts the Red Queen

Hypothesis. evaluate the advantages and disadvantages of the two modes of reproduction in the snail (in

the context of its need to avoid parasitic infections).

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