Presentation is loading. Please wait.

Presentation is loading. Please wait.

Understanding the Diversity of Life – Part 1

Similar presentations

Presentation on theme: "Understanding the Diversity of Life – Part 1"— Presentation transcript:

1 Understanding the Diversity of Life – Part 1
Evolution Understanding the Diversity of Life – Part 1

2 Evolution “Nothing in biology makes sense EXCEPT in the light of evolution.” Theodosius Dobzhansky Charles Darwin in later years

3 History of Evolutionary Theory

4 Early Ideas about Earth’s Organisms
Aristotle believed species were fixed creations arranged by their complexity

5 Early Ideas about Earth’s Organisms
Carolus Linnaeus 1st to group similar organisms and assign them Latin names Two word name (Genus species) Known as Binomial nomenclature

6 Early Ideas about Earth’s Organisms
Georges Cuvier Some species’ fossil records disappeared in more recent layers Stated that species disappear due to a catastrophic event of the earth’s crust

7 Early Ideas about Earth’s Organisms
James Hutton & Charles Lyell Stated that various geological forces constantly changed the planet Changes in Earth’s crust were due to slow continuous processes Idea Known as Gradualism or Uniformitarianism

8 Early Ideas about Earth’s Organisms
Hutton & Lyell, cont. Geological processes moved at uniform rates; building & wearing down Earth’s crust Proposed that the Earth was millions of years instead of a few thousand years old

9 Early Ideas about Earth’s Organisms
Reverend Thomas Malthus Studied macroeconomics Stated that populations could not grow indefinitely This growth would be stopped by: Disease Famine War

10 Lamarck’s Theory of Evolution
Jean-Baptiste Lamarck One of first scientists to understand that organisms change over time Put forth an idea called Inheritance of Acquired Characteristics through Law of Use and Disuse

11 Lamarck’s Theory of Evolution
Proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime Examples: blacksmiths & their sons (muscular arms) giraffe’s necks longer (from stretching) These traits could then be passed on to their offspring Over time this would lead to new species


13 Lamarck’s Mistakes Inheritance Of Acquired Traits
Traits Acquired During Ones Lifetime Would Be Passed To Offspring If true, clipped ears would pass to offspring!

14 Lamarck’s Mistakes Lamarck did NOT know how traits were inherited (traits are passed through genes) Genes are NOT changed by activities in the life of an organism Change occurs through mutations of genes These mutations occur before the organism is born

15 Charles Darwin the Naturalist

16 Charles Darwin Born Feb. 12, 1809 A naturalist Collector/identifier of plant and animal specimens Formed his ideas about evolution sailing on the HMS Beagle for the Galapagos Island in 1831

17 The Galapagos Islands Small group of islands 1000 km west of Ecuador
Very different climates and geography on each island Animals on each of the islands similar but unique

18 The Galapagos Islands Islands all formed by action of volcanoes
Island species varied from mainland species & from island-to-island species Each island had long or short neck tortoises

19 The Galapagos Islands Finches on the islands resembled a mainland finch Different types of finches appeared on the islands where the available food was different (seeds, nuts, berries, insects…) Finches had beaks adapted to their type of food gathering


21 The Struggle for Existence
Darwin’s Observations and Conclusions

22 Darwin’s Observations
Patterns of Diversity Unique adaptations in organisms Species not evenly distributed Examples: Australia: kangaroos South America: llamas Africa: elephants

23 Darwin’s Observations
Darwin collected living organisms and fossils on his voyage Took these back to England to study This species NO longer existed. What had happened to them?

24 Giant Ground Sloth

25 Glyptodon – Ancestor of Modern Armadillo

26 Darwin’s Observations
Unlimited resources will allow organisms increase exponentially, generation to generation In nature, populations tend to remain stable in size Environmental resources are what limits population size

27 Darwin’s Observations
Individuals of a population vary in their characteristics with no two individuals being exactly alike. Much of this variation between individuals is inheritable.

28 Darwin’s Conclusions Production of more individuals than can be supported by the environment leads to a struggle for existence Only a fraction of offspring survive each generation He called this “Survival of the Fittest”

29 Darwin’s Conclusions Individuals who inherit characteristics most fit for their environment are likely to leave more offspring than less fit individuals He called this “Natural Selection”

30 Ideas that Shaped Darwin’s Thinking

31 Ideas that Shaped Darwin’s Thinking
Hutton & Lyell Expanded Earth’s age from 6000 to billions of years Explained geological processes that shaped the earth Helped Darwin understand the presence of sea shells in the Andes mountains at 12,000+ feet

32 Ideas that Shaped Darwin’s Thinking
Malthus’ Influence Babies are born faster than people die Total population size limited by resources such as the food supply High birth rates & limited resources would force life & death competition Each Species Struggles For: Food Living Space Mates

33 Darwin’s Theory of Evolution
Organisms Change Over Time

34 Evolution: Defined Evolution is the slow , gradual change in the alleles of a population over time

35 Darwin’s Theory of Evolution
The unequal ability of individuals to survive and reproduce leads to a gradual change in a population, with favorable characteristics accumulating over generations (Natural Selection) This creates new species

36 Darwin’s Theory of Evolution
Descent with Modification: Organisms descended from common ancestors Organisms change with time, diverging from a common form

37 Darwin’s Theory of Evolution
Natural Selection: Driving force for evolution During the struggle for resources, strongest survive & reproduce Idea that at least some of the beneficial differences between individuals are inheritable .

38 Publication of: “On The Origin of Species”
Upon his return To England, Darwin spent 25 years developing his observations into the Theory of Evolution He hesitated to publish because: 1. He knew that his theory would be extremely controversial and would be attacked 2. His theory challenged established religious & scientific beliefs; particularly about the Creation of Man

39 “O’ no you didn’t! This was my Idea!” - Darwin
Alfred Russel Wallace Fellow naturalist Sent an essay of his work to Darwin to review Had independently come to the conclusion that species changed over time because of their struggle for existence When Darwin read Wallace’s essay, he knew he had to publish his findings

40 Publication of: “On The Origin of Species”
Darwin presented Wallace’s essay & some of his work at a conference in July of 1858 Then he started work on his book “Origin of Species” which was published in 1859 Spent the rest of his life refining his ideas about evolution Darwin died in 1882, the father of 10 children; 7 survived to adulthood


Download ppt "Understanding the Diversity of Life – Part 1"

Similar presentations

Ads by Google