This document presents an overview of evolution through natural selection. It defines evolution as cumulative heritable changes in a population over time. It provides evidence for evolution through fossil records showing changes over generations, as well as examples of artificial and natural selection leading to changes in populations. Specifically, it discusses how overproduction of offspring combined with variation and environmental pressures results in natural selection of traits increasing the chance of survival, and gives examples of antibiotic resistance in bacteria and pesticide resistance in rats evolving through this process.

1. Evolution
BIOLOGY PRESENTATION
DONE BY: LAILA BANGWAR &
LUJANE PAGGANWALA

2. What is Evolution
“Defined as a process of Cumulative change in
the Heritable characteristics of a population.”

4. Evidence for evolution by Fossil records
• There are several ways of proving evolution
through the process of natural selection.
• Fossil records are one of the ways.

6. Artificial Selection
• Another way to prove evolution is by artificial
selection.
• What is artificial selection?

8. Homologous anatomical structures
• Homologous anatomical structures is another
way that evolution is proven
• What is Homologous anatomical structures?

10. Over-production of offspring
• Many times populations over produce
offspring, more then what the environment
can handle or support.
• Some organisms which do so are:
-Plants
-Mushrooms
-Fish

12. Why the environment cannot support the
over production of off springs
• The environment cannot support all the
offspring due to lack of availability of water
and other nutrients in order for the offspring
to survive.

13. Consequences of over-production
• The result of overproduction causes a
competition between the organisms in order
to survive. Also known as the struggle of
survival.
• It could be explained as survival of the fittest,
as Charles Darwin himself referred it, though
it is much more complicated then just that.

14. Variation
• Some members of a species show variation.
• Usually those who sexually reproduce, show
more variation

16. Natural selection
• Charles Darwin’s most famous theory.
• What is natural selection?
• Steps involved in evolution by natural selection:
-overproduction of offspring
-Variation in offspring, both harmful and beneficial
-environmentally adapted genetic characteristics
-Passing on of favorable genetic characteristics
-All this accumulates to result in evolution.

17. Examples of evolution-in response to
environmental change
• Evolution usually is a time consuming process,
but sometimes natural selection may take
place quicker, in months or decades, instead
of a million years.
• Two examples of natural selection could be:
- Antibiotic resistance in bacteria
- Pesticide resistance in rats

18. Antibiotic resistance in bacteria
• Antibiotics are basically medications which kill
bacteria.
• In certain conditions, some bacteria may
become resistant to the antibiotic.
• This takes place due to two reasons which are:
-Mutations
-Plasmid transfer

20. Pesticide resistance in rats
• Pesticides are those chemicals which are used
to kill organisms that are pests such as rats.
• Just like how bacteria become resistant to
some antibiotics, pests (in this case, rats)
become resistant to pesticides, in some
conditions.

22. Evolution

23. Bibliography
• Charles Darwin & Evolution. (n.d.). Charles Darwin &
Evolution. Retrieved August 14, 2014, from
http://darwin200.christs.cam.ac.uk/pages/index.php?page_
d3
• Introduction to Evolution. (n.d.). Vimeo. Retrieved
August 17, 2014, from http://vimeo.com/19451460
• Ward, W., & Damon, A. (2007). Pearson baccalaureate:
higher level (plus standard level options) : biology
developed specifically for the ib diploma. Harlow,
[England: Pearson Education.

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