reproduction strategies for success student trail (in … 27 days after mating the female lays one...

Reproduction: Strategies for Success– Student Trail

VCE Biology Units 1 and 2

Functioning Organisms/ Adaptations of Organisms Student Trail

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Reproduction: Reproduction:

Strategies for SuccessStrategies for Success

Student Trail

Introduction This program provides the opportunity for students to observe animals first hand to collect data related to reproduction, reproductive technology and captive breeding.

The program is designed to meet the requirements of the School-assessed Coursework (SAC) component for Unit 1 Outcome 2 and/or Unit 2 Outcome 1(practical activity). It addresses the key knowledge and skills related to Biology Unit 1, with particular emphasis on the mechanisms and systems of reproduction and also Biology Unit 2, with emphasis on reproductive adaptations, systems and strategies.

Aims • To develop an understanding of the ways in which animals reproduce

• To identify and describe reproductive strategies in selected animals

• To consider specific examples of reproductive technologies as they apply to captive breeding programs at Healesville Sanctuary.

Program instructions This trail has been designed to provide you with the opportunity to explore the Sanctuary and discover more about the diverse nature of reproduction in a variety of Australian animals.

There are two sections for you to complete:

• Detailed questions regarding reproductive strategies of various animals

• Conclusion (can be completed after the session).

VCE Biology Unit 1 Unity and

Diversity Area of Study 2: Functioning

Organisms VCE Biology Unit 2 Organisms and their Environment

Area of Study 1: Adaptatations of Organisms


Mammals

Amazing Marsupials

Kangaroos Most marsupials give birth to under developed young that migrate to the pouch to complete their development. In some marsupials such as the kangaroo, copulation can produce a fertilised egg that replicates (by mitosis) to form a group of undifferentiated cells called a blastocyst. At this stage, the blastocyst implants and commences development into an embryo. In unfavourable environmental conditions, some marsupials delay this implantation and this is referred to as diapause. Some kangaroos can, at any one time, have an embryo in diapause, a newborn joey and an older joey all dependent on the mother for nutrition, development and survival.

In order to determine the birth date of the young joey, the Keepers will measure the length of the hind limbs and then estimate the date of birth. Explain, with reasons, why the actual birth date is not known.

Suggest the reproductive and survival advantages of marsupial diapause.

Qualitative data collection

Find a kangaroo or wallaby mother with her joey.

Work with a partner. For a period of 5 minutes record everything the mother does.

At the end of the 5 minutes try to classify the behaviour into:

Parenting Behaviour Other Behaviour

Newborn Red Kangaroos are tiny and undeveloped.

(Diagram shows actual size.)


Did you know that after the breeding season, all male Antechinuses (shown below) die from exhaustion, leaving behind an all female population!

Other marsupials:

Not all marsupials have a forward opening pouch like a kangaroo.

Investigate how the pouch is different from that of a kangaroo in the following

animals. All of these mammals except the numbat can be seen at Healesville

Sanctuary: Tasmanian Devil, Wombat, Koala, Northern Quoll, Spot-tailed Quoll,

Antichinus and Numbat.

Marvelous Monotremes

Echidna and Platypus Monotremes includes both the platypus and the echidna (of which there are two species, one living in Australia and one in Papua New Guinea) Members of the order Monotremata, have only one orifice for the passage of urine, faeces and reproductive products. Echidnas lay eggs with a soft shell directly onto the ‘pouch’ of the mother. A muscular flap of skin folds over to form the pouch. The echidna hatchling emerges from the egg by using its ‘egg tooth’ and within hours it drinks milk. The platypus lays its eggs in a burrow.

What similarities are there between Monotremes and Reptiles and Birds?

What similarities and differences exist between Monotremes and Marsupials?

The Echidna Echidnas breed in the winter. During this times male echidnas will form a ‘train’ behind a female in the hope that she will become receptive to mating. Echidna trains can last up to six weeks and can have any number of echidnas from 2– 11 but 3– 4 is most common. During this time the echidnas forage together and the males occasionally nudge the female to determine if she is receptive. When ready she digs a trench. Males also dig beside her and try to push each other away. The echidna who digs himself in closest to the female will mate with her.

Comment on the reproductive advantage in forming a ’love train’.

Compile a list of the issues that would have to be resolved before the echidna could be bred successfully and hand raised in zoos and sanctuaries.


The Platypus Platypus mates from July to November. During this time the male’s spurs, present on the hind legs, are filled with venom. After an elaborate courtship where the male and female swim in circles, mating occurs. The female constructs a deep burrow which becomes the nest chamber. About 27 days after mating the female lays one to three eggs (usually two). These hatch 10 days later. The mother suckles the young for 3 months before the young emerge from the burrow.

Suggest a use of the venomous spur in the male platypus.

Ten days is a very short incubation time for platypus eggs compared to the eggs of birds which can take months to hatch.

Comment on the likely maturity level of the platypus on hatching.

What reproductive processes are in place to ensure the survival of the young platypus?

Compile a list of the issues that would have to be resolved before Platypus could be bred successfully and hand raised in zoos and sanctuaries.

Perfect Placentals

Dingo

The Dingo is a placental mammal which unlike the domestic dog has only one breeding season per year. Only the dominant alpha male and female will breed. The alpha female will kill any neighboring litters. Up to five young are born after a gestation of nine weeks. The young are cared for by both parents. Once weaned the young are fed meat which is regurgitated by the parents. The pups then learn to hunt for themselves.

The gestation period in placental mammals is considerably longer than in marsupials. What is the consequence for the offspring of placental mammals?

Can you see our new platypus babies?

Where would they be hiding?

The first platypus specimen sent back to England was thought to be a hoax and the work of a clever taxidermist!


What advantage is there in having only the dominant animals breeding?

As a result of interbreeding with dogs introduced by European settlers, the number of purebred dingoes is in decline. The Alpine dingo on display at Healesville Sanctuary is thought to be extinct in the wild due to interbreeding.

If two animals are similar, able to breed and produce fertile young they are said to be in the same species. What can be said of the domestic dog Canis lupis familiaris and the dingo, Canis lupis dingo?

At the Sanctuary there are 3 males and 3 females which are housed in male/female pairs. We are no longer breeding these animals.

Why do you think that the Sanctuary does not want to breed the dingoes? List as many reasons as you can.

What reproductive technology could be used to prevent dingoes from breeding?

Research question

Find out other ways that dingoes and domestic dogs differ. Include physical differences, behavioural and physiological differences.

Birds Some birds exhibit unusual strategies and elaborate courtship displays to attract a mate and entice copulation. After mating, all birds lay their shelled eggs on land (rather than in water).

Satin Bower Bird Look for the bower that is made by a Satin Bower Bird.

Draw a diagram of the bower and describe the materials from which it is made:

The Satin Bower Bird can be found in the Woodland Bird Aviary near the Goannas.


What is the significance of the shape of the bower and the presence of the blue

objects?

Choose another pair of birds and observe their behaviour for 5 minutes. Record your observations. Describe some other strategies used by birds to assist their reproduction.

Emu During pair formation the female dominates the male. He later becomes aggressive towards other males and the female and she disperses. The male gathers the eggs the female has laid and incubates the eggs for 55 days. A nest can contain the eggs of several females or even the eggs that other males have fathered.

The young are a cream colour with brown stripes. They leave the nest at 2– 7 days when they can feed themselves but remain with the male for up to 6 months. At 12 months they are fully grown. They can breed at 20 months.

Outline the advantages and disadvantages of this reproductive strategy in the table below.

How do you think their hatching is able to be synchronised? What advantage is there in the young hatching at the same time?

Reptiles

Snakes and Lizards Snakes and lizards are generally considered to be solitary, lay eggs (viviparous), usually produce a large number of young and show little parental care. Eggs have leathery shells and are laid on land. Some local

Did you know……

Whilst incubating the eggs, male emus do not eat, drink, defecate or leave the nest!

Advantages Disadvantages


reptiles such as the Tiger Snake and the Eastern Bluetongue Lizard and others from cooler areas are live bearers (ovoviviparous). The Shingleback Lizard is known to be monogamous, finding its mate each breeding season to mate again.

What advantage is there in having eggs with a leathery shell?

Comment on the relationship between the number of young produced and the level of parental care provided for the young of reptiles.

What advantages and disadvantages are there in being an :

Oviparous (egg laying) reptile?

Ovoviviparous (live bearing) reptile ?

How do you think the Shingleback Lizard would locate its previous mate during the breeding season?

Amphibians

Frogs Amphibians such as frogs do not mate but undergo external fertilisation of the eggs. After the male stimulates the female, she releases her many unfertilised eggs into the water. The male deposits sperm on top of the egg mass and the sperm can swim to fertilise the eggs. Frog’s eggs are very numerous and have a jelly like coating. The young tadpoles develop in the water and later go through metamorphosis to become adult frogs that can leave the water.

What are the connections between the habitat of the animal, the type of fertilisation shown and the nature of the eggs produced.

List at least two reasons for frogs eggs being so numerous.

Can you find out……

How do snakes mate?

How do keepers determine the sex of a reptile?

With external external external external fertilisation the sperm and egg unite outside the body.


Describe how frogs attract a mate of the same species during the breeding season.

What is the survival advantage for frogs in undergoing metamorphosis?

Climate change and its associated impacts is affecting many species of plants and animals around the world. Frogs are one of the animal groups particularly at risk. There is a global amphibian crisis with many species disappearing from the planet. With regard to reproduction comment on why this is the case.

What everyday actions can you implement to reduce the likelihood of climate change and its effect on amphibians.

Research questions:

Make a list of at least five other animals that undergo external fertilisation.

or

Find out about the reproductive strategy of either the Australian Water Holding Frog or the Corroboree Frog.

Invertebrates

Stick Insects Healesville Sanctuary exhibits several species of stick insect. Stick insects are very well camouflaged against the trees on which they feed. Sexual dimorphism is pronounced with the female much larger than the male. After mating, the female lays a large number of eggs which fall to the ground.

Locate a male and female stick insect and note the species name. Estimate and record your observations of the following:

1. length and width at the widest point of each stick insect in centimetres;

2. length of the abdomen of each stick insect in centimetres;

Can you find out….

the amazing story of the rediscovery of the Lord Howe Island Stick Insect

ARAZPA pro-claimed 2008 as ‘The Year of the Frog’ to raise awareness of the Global Amphibian Crisis.


Suggest a reason for the pronounced sexual dimorphism in the species you observed.

Examine some stick insect eggs.

Suggest some of the survival advantages conferred on the eggs, based on their appearance .

Parthenogenesis is a type of asexual reproduction found in some animals, including stick insects, where offspring develop from unfertilised eggs.

Explain the difference between sexual and asexual reproduction. Give some examples of other living things that undergo each type of reproduction.

Suggest the reproductive advantages and disadvantages of parthenogenesis in stick insects.

Zoos Victoria Conservation Breeding programs Zoos Victoria is involved in a number of important conservation projects. Research projects have involved investigating ways of maximising the breeding potential of many species which are threatened within Victoria.

Brush-tailed Rock Wallaby Research for reproduction of the Brush-tailed Rock Wallaby has involved investigations and trialling of a technique called ‘cross fostering’.

Watch the DVD of the Brush-tailed Rock Wallaby recovery program.

What species of wallaby is used as the surrogate mother for the Brush-tailed Rock Wallaby?

How does cross fostering accelerate breeding in the Brush-tailed Rock Wallaby?

For more information on the Brush-tailed Rock Wallaby research go to: http://www.zoo.org.au/conservation/btrw.htm


Melbourne Zoo Healesville Sanctuary Werribee Open Range Zoo Post Office Box 74 Badger Creek Road K Road

Parkville Vic 3052 Healesville, Vic 3777 Werribee, Vic 3030

Ph: 61 3 9285 9355 Ph: 61 3 5957 2819 Ph: 61 3 9731 9635

Fax: 61 3 9285 9340 Fax: 61 3 5957 2873 Fax: 61 3 9731 9644

© These sheets may be reproduced for teaching purposes. Permission to reproduce them for other pur-

poses may be obtained from Zoos Victoria.

reproduction strategies for success student trail (in … 27 days after mating the female lays one...

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