21.1.1 Reproductive Technologies

Blueprint of Life
Topic 21: Reproductive Technologies
Biology in Focus, HSC Course
Glenda Childrawi, Margaret Robson and Stephanie Hollis
 identify how the following current reproductive
techniques may alter the genetic composition of a
 artificial insemination
 artificial pollination
 Cloning (we will discuss this next lesson)
Selective breeding techniques are
reproductive technologies that may be
used to achieve hybridisation. Selective
breeding can be thought of as a form of
artificial selection imposed by humans,
when they conduct deliberate crosses
of living organisms to obtain a
combination of desirable characteristics
in the offspring. (This contrasts with
natural selection where environmental
conditions determine which individuals
produce the most offspring.)
Selective Breeding In Plants
 Selective breeding in plants is by
means of artificial pollination.
Records show that artificial
pollination is not only a modern
practice. It was used in ancient
times—an Assyrian carving that
dates back to 870 BCE shows the
artificial pollination of date palms.
Selective Breeding In Plants
Artificial pollination was used by Mendel in his experiments with
pea plants in the 19th century and was also used by scientists such
as Farrer who were involved in hybridisation studies; it is still
used today. In the past century, thousands of new breeds of plants
have been created using artificial pollination.
Selective Breeding In Plants
This process involves removing
the stamens of a flower and
dusting the pollen onto the stigma
of the same flower (selfpollination) or another flower
(cross-pollination). This, like the
other selective breeding processes,
gives the breeder a greater degree
of control over the breeding
Selective Breeding in Animals
 Selective breeding in animals
involves mating a male and female
with desirable characteristics in the
hope that some offspring will
inherit both characteristics.
For example, crossing a male of the
Friesian variety (known for the ability to
produce large quantities of milk) with a
Jersey cow (which produces creamy milk)
will create some offspring who
produce large amounts of creamy
Selective Breeding in Animals
Offspring that reflect this desirable trait are then selected for
further breeding. In selective breeding, both parent individuals
are different varieties of the same species, so the offspring
produced are fertile.
Selective Breeding in Animals
 The breeding of undesirable side effects.
For example a physical disadvantage arises when Friesian cattle
are crossed with Jersey cattle. Some of these hybrid cows have
such large udders that they can hardly walk.
Selective Breeding in Animals
 Costs (time and money).
Selective mating is time-consuming
and costly. It involves the transport
of large animals over long distances,
risking putting them together with a
breeding partner of the opposite sex,
hoping they will not injure each
other and then waiting for them to
mate. To overcome these problems, a
newer technology called artificial
insemination was introduced.
Artificial Insemination
 This process involves taking
sperm from a chosen male
and artificially introducing it
into several selected females.
This became widespread from
the 1980s onwards, with the
discovery of the effective
storage and transport of sperm.
Artificial Insemination
The semen containing sperm may be removed from the male
(using mechanical stimulation), and the fluid is first chilled and then
frozen in liquid nitrogen for long-term storage and transported.
Artificial Insemination
 Transportation is easier
 Its cost effective
 It reduces the danger to animals of
injury in transit or during mating.
 Many females can be inseminated and
so one male can sire offspring with
several females. Since the semen can be
frozen indefinitely, a male can be dead
but still produce offspring.
Artificial Insemination
Artificial insemination is also being used in conservation, to
increase the numbers of endangered species—Monash University
PhD student Jonathan Daly conducted the first artificial
insemination of a shark (he used a broad-nosed seven-gill shark as a
model species) to try to develop a technique to apply to grey nurse
sharks whose numbers are dwindling on the east coast of Australia.
Artificial Insemination
Myzuri, a male gorilla, is the first
successful gorilla produced using
this reproductive technology, which
was carried out at Melbourne Zoo
by Professor David Galloway of the
University of Melbourne.
Artificial Insemination
 If many offspring arise from one
father, it can lead to reduced
genetic variability.
Artificial insemination has become the
principal assisted reproductive
technology method for many types of
cattle, sheep and pigs, as well as
performance and sport horses around
the world, including in Australia.
In Vitro Fertilisation(IVF)
An egg is fertilised by a sperm outside the mother’s body (in an
artificially created environment, e.g. a Petri dish) and then transferred into
the biological mother, into a surrogate mother or frozen in liquid
nitrogen for later transplantation or for use in scientific research. This
method is often used in cases where there is decreased fertility in one
or both of the parents.
Genetic Impact
With the use of selective
breeding techniques, humans
alter the genetic composition of
the breeding population by
selecting organisms with traits
considered by the breeder to be
of advantage and carrying out
controlled breeding of these
Genetic Impact
The alleles that increase in frequency in the gene pool of the
population are therefore those that have been selected by the
breeder rather than by nature.
Genetic Impact
The survival and reproduction of an individual within the
population depend on the presence of alleles that enable them to
increase the output of a product that is useful to humans, rather
than alleles that increase their fitness in terms of suitability to the
environment or reproductive success.
Genetic Impact
There is a short-term increase in the genetic diversity when new
hybrid species are created, but in the longer term the continued
breeding of the same hybrid lines decreases genetic diversity.
Genetic Impact
Artificial pollination,
insemination and in vitro
fertilisation are technologies that
do not allow humans to
determine the exact
combination of genes that will
be passed on. Is there a way that
we can???

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