Canis lupus

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14 Δεκ 2012 (πριν από 4 χρόνια και 10 μήνες)

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Biological Change


over Time

Ms. Cowman

SBI3U

Mutations: The Source of Genetic Variation


All species exhibit genetic variation


Mutations create new genes that provide a
continual supply of new genetic information



Mutations may be:


NEUTRAL
-

provide no benefit or harm to the
individual


HARMFUL
-

reduce the reproductive success of an
organism, do no accumulate over time


BENEFICIAL
-

produce a change in the individuals
phenotype that gives the individual an
advantage, accumulate over time

Mutations can have significant
consequences


Bacteria have developed resistance to antibiotics
are becoming more widespread as less
-
resistant
strains are killed off.





Viruses can mutate to become more virulent
(harmful), which can increase its ability to spread.


Selective Breeding: Artificial Selection of
Traits


Domestication of Animals and Plants


Provide humans with the majority of our food
supply


Formed the basis for the development of modern
civilization



Domestication is the changing of members of a
species to suit human needs through controlled
captive breeding (Artificial Selection)


Examples of Artificial Selection

First species to be domesticated:
Canis

lupus,
the wolf

Wild Sea Cabbage

(1000’s of years) 7 vegetables

How does artificial selection work?


The breeder picks seeds from the plants that
have the best
flavour

or largest fruit and sows
them


The plants cross
-
pollinate each other
producing more fruit with the desired trait

Genetic Engineering


Transfer beneficial genes from an individual of
one species to an individual of another species


If successful, genetically modified individual is
mass produced

Power of Artificial Selection


Production of individuals that exhibit traits that
are far beyond the natural variability present in
the original population





Can reduce genetic diversity within a
population



Breeder
favours

only certain traits in a
population, then many alleles linked to other
versions of a particular characteristic are reduced
or eliminated

Implications for Natural Populations

What do we know about genetics?




-

All species exhibit genetic variation



-

Mutations produce heritable changes in

individuals, and these changes may be

beneficial, harmful, or neutral



-

Some species, such as bacteria and insects, can

change over relatively short periods of time



-

Some domesticated species have changed

dramatically under the influence of artificial

selection