This image cannot currently be displayed. Unit 5 - Evolution 2. Mr.Yeung

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1 This image cannot currently be displayed. Unit 5 - Evolution 2 Mr.Yeung

2 Who is Charles Darwin? Charles Darwin ( ) English lad Has a degree in Theology from Christ s College in Cambridge Was a naturalist and geologist Set sail on HMS Beagle in 1831 to South America and then to Galapagos Islands (West of Peru) over the span of 5 years.

3 Other key players that contributed to the idea of evolution James Hutton ( ) and Charles Lyell ( ) Concluded that the Earth is very old and has changed slowly over time due to natural processes. Erasmus Darwin ( ) Charles Darwin s grandfather.) suggested that competition between individuals could lead to changes in species. Jean Baptiste Lamarck ( ) He hypothesized that living things evolve through the inheritance of acquired characteristics.

4 Thomas Malthus ( ) observed that human populations cannot keep growing indefinitely. If the human birth rate continued to exceed the death rate, eventually humans would run out of living space and food. Alfred Russell Wallace proposed a Theory of Evolution by natural selection similar to that of Darwin s theory. But was not remembered for his contributions.

5 Galapagos Islands Collected various birds such as finches, mockingbirds and other animals. Interesting point was that he noticed that different islands have their own varieties of animals.

6 Voyage of the Beagle

7 Jean Baptiste Lamarck Change through use and disuse: If an animal began to use an organ more than they had in the past, it would increase in its lifetime. Example: If a giraffe stretched its neck for leaves, its offspring would inherit the longer neck, and continued stretching would make it longer still over several generations. Doctrine of Acquired Characteristics

8 Development of the Theory of Evolution At the time, Darwin believed that animals were static (no changes) But observed that animals can be artificially selected by breeding the desired traits. He extended this to nature where organisms would do the same. This is called Natural selection where nature selects the favourable traits

9 Main points of Darwin s theory of evolution If given enough time, a population, could be modified. The main points of Darwin s theory of evolution 1. Overproduction More offspring are produced by an organism than can possibly survive 2. Variations between individuals can be inherited and passed down 3. Competition Competition between organisms 4. Natural selection The most fit (best adapted) survive and reproduce 5. Speciation new species form from ancestral species by natural selection.

10 Variation in traits Differential reproduction Surviving brown beetles Brown adaptation will be carried on

11 Survival of the Fittest How adaptations help a species survive.

12 What makes an organism fit? Survival of the fittest describes a struggle for life in which only those organisms best adapted to existing conditions are able to survive and reproduce. These organisms are considered fit for their environment. The fit has adapted to the environment.

13 Adaptation vs. Acclimatization Adaptation: the result of natural selection. Species that are well adapted to their environments tend to be successful. Successful means they survive and reproduce, but again they are not perfect. If the environment changes, they may not be well-suited anymore and may die. Acclimatization: this occurs when an organism becomes accustomed to changing environmental conditions. It is NOT the result of natural selection. It does NOT cause a change in the gene pool of the species.

14 Examples of Acclimatization Many plants, such tomatoes, can survive freezing temperatures, if the temperature gradually drops lower and lower each night over a period of days or weeks. The same drop might kill them if it occurred suddenly!

15 Types of Adaptation We are going to look at three different kinds of adaptations 1.Behavioral 2.Structural 3.Physiological

16 Types of adaptations Camouflage (Structural) Blending in to its surroundings Mimicry (Behavioural) Copying another organism for protection, reproduction or aggressive behavior. Antimicrobial resistance (Physiological) Becoming resistant to antibiotics

17 Camouflage Pygmy seahorses

18 Leafy Sea dragon

19 Blue Ringed Octopus

20 Flounder

21 Leaf Frog

22 Mimicry Plain tiger (left) next to mimic butterfly (Hypolimnas missipus)

23 Hooded malpolon showing Cobra like defensive behaviour

24 This jumping spider uses color and shape to mimic the ants that it hunts.

25 How natural selection leads to changes to populations Organisms are adapted in how they respond to the environment. These behaviors are the result of natural selection those individuals that survive a change in environment, pass the genes responsible for the behavioral trait to their offspring.

26 Male Bowerbirds create elaborate courtship displays to entice females

27 Videos Jumping spider (ant) Bower Bird Mimic Octopus Darwin s Dangerous Idea