Research in Selective
Breeding
Kiki LAM
Y9MA
What is Selective Breeding? [1]
● Selective breeding involves choosing
parents with particular characteristics
to breed together and produce
offspring with more desirable
characteristics.
● Selective breeding aims to adapt an
organism’s characteristics in a way that
is desirable to the humans that breed
What is Selective Breeding? [1]
●
Humans have selectively bred plants and animals for thousands of years
including:
○
crop plants with better yields
○
ornamental plants with particular flower
shapes and colours
○
farm animals that produce more, better
quality meat or wool
○
dogs with particular physiques and
temperaments, suited to do jobs like herd
sheep or collect pheasants.
How does selective breeding work?
● An organism’s characteristics are
partly determined by the
combination of gene variants that
are passed on from one generation
to the next.
● We can take advantage of this to
selectively breed animals or plants,
choosing parents with particular
characteristics to produce offspring
that have those characteristics.
Types of selective breeding [1]
Inbreeding
●
If we want to establish a population of organisms
with predictable characteristics we tend to “inbreed”.
●
Inbreeding is when the animals bred are very close
relatives, such as siblings.
●
Continued inbreeding results in offspring that are
very genetically alike.
●
After many generations of inbreeding, the offspring
will be almost genetically identical, and will produce
identical offspring. When this happens, an organism
is described as inbred or purebred.
Examples of purebred animals are
Labrador Retriever dogs and Siamese cats.
Types of selective breeding [1]
Linebreeding
● It involves breeding together more
distant relatives, such as cousins.
● This reduces the rate at which the
breed becomes ‘purebred’, reducing
the risk of ill-health that can
sometimes be seen with purebred
individuals.
Types of selective breeding [1]
Crossbreeding
● Crossbreeding involves breeding two
unrelated individuals.
● This is often used to produce offspring with
desirable characteristics from two different
individuals.
● Crossbreeding two purebred organisms
will produce offspring that display the
characteristics of interest.
Examples of selective
breeding
●
One of the earliest examples of selective breeding
is the domestic dog (Canis familiaris), which
humans have been breeding for at least 14,000
years [4].
●
Scientists believe that the domestic dog evolved
from the wild gray wolf (Canis lupus), and
through artificial selection, humans were able to
create hundreds of different dog breeds [4].
●
Poodles are crossed with Labrador Retrievers to
combine a Poodle’s low-shedding coat with the
Labrador’s calm, trainable temperament. The
resulting ‘Labradoodle’ is a guide dog suitable for
people with allergies [1].
Examples of selective breeding
●
●
Cabbage, broccoli, cauliflower, Brussels sprouts,
and kale are all vegetables derived from the same
plant, Brassica oleracea, also known as wild
cabbage. By isolating wild cabbage plants with
specific characteristics, farmers were able to create
a variety of vegetables from a single source, each
with different flavors and textures.
Broccoli, for example, was developed from wild
cabbage plants that had enlarged flower
development while kale was derived from Brassica
oleracea with larger leaves.
Examples of selective breeding
●
●
The earliest records of maize indicate that the
plant was developed in southern Mexico
6,000-10,000 years ago from a grass called
teosinte. Scientists believe that early farmers
selected only the largest and tastiest kernels of
teosinte for planting, rejecting punier kernels.
This process allowed the farmers to develop
corn very quickly, as small changes in the
plant's genetic makeup had dramatic effects on
the grain's taste and size. Despite their physical
dissimilarities, teosinte and corn only differ by
about five genes. [3]
Examples of selective breeding
Examples of selective breeding [2]
Traits that have been improved by crop breeding include :
1.
2.
3.
4.
5.
6.
7.
8.
Yield (increasing how much is safely grown on the same amount of land)
Resistance to pests and diseases
Adaptation to environmental stresses such as heat, drought, frost, and salty soils
Nutritional value
Ease of harvest
Efficiency of breeding techniques
Taste, color, and texture
Creation of seedless varieties of fruits and vegetables
Problems with selective breeding [1]
●
Selective breeding often results in a population of
animals or plants with very similar genetics.
●
Similar genetics means that the population will have
the same strengths but also the same weaknesses.
●
Infectious diseases are more likely to spread
through genetically similar populations because
they are vulnerable to the same diseases.
●
Inbred populations that involve breeding closely
related individuals, are more likely to suffer from
genetic conditions caused by recessive gene variants
because they are more likely to inherit two copies of
the recessive variants, one from each parent.
References
1.
2.
3.
4.
https://www.yourgenome.org/facts/what-is-selectivebreeding#:~:text=Selective%20breeding%20involves%20choosing%20parents,crop%20plants%20with%
20better%20yields
https://www.crops.org/about-crops/breeding
https://www.biointeractive.org/sites/default/files/PoppedSecret-Educator-film.pdf
https://www.treehugger.com/what-is-selective-breeding-4858804