1. Changes in Organisms Over Time1

2. Where do I live? 4 What type of environment am I best “fit” for?
Hot/cold????
Wet/dry???
Why
Organisms have traits (GENES) that help them to survive in different environments.

3. A is a small change in a trait that makes an individual slightly different from other members of its species.
All organisms in a population are not the same. Variation/diversity exist.
What causes this variation??

4. What is Fitness? 5
Fitness is a measure of (survive long enough to reproduce)
Reproductive success: Having traits so that an organism is able to pass on genes onto the next generation (and in a way so that the next generation can also pass those genes on)
Any trait that promotes survival — at least until one's reproductive years are over — fitness.
Such traits are called adaptations.
GAME

5. What if an organism has a trait
What if an organism has a trait. that makes it impossible to live in its environment? 6
The organism will not survive.
If it does not survive— it CANNOT reproduce.
If it does not reproduce—its genes are not passed to the next generation.

6. What if the environment changes?7
If they do not have the traits (genes) that enable them to survive…they die, and DO NOT reproduce.
If they do have the traits, then they survive…and reproduce.
SO… the next generation has more of the “fit” traits for THAT environment. .
This is a very slow process….does not occur over night…many generations must past before any change in the population can be seen.
Natural Selection

7. Current Theory … Natural Selection8
Also know as “ ”
Only certain members of the population will survive and .
Ones that survive are most suited to the environment—they are the most fit!!.
survival of the fittest

8. Humans have been doing this for 1000s of years!9 .
provides a model that helps us understand natural selection. People have been artificially selecting domesticated plants and animals for thousands of years.
Broccoli and brussels sprouts bear little superficial resemblance to their wild mustard relatives (left).

9. Humans select and breed for certain traits.
Dog Breeds
Corn
Pigs
Humans select and breed for certain traits.
Examples: The largest hog, the cow that gives the most milk, fastest horse, or cutest dog.

10. Where do NEW traits come from?10
Where do NEW traits come from?

11. How do new traits arise? Mutations. Sexual Reproduction. 11
Mixing of genes makes new combinations
A combo of traits may be necessary for survival……so… sexual reproduction and crossing over can create new combination of traits.

12. Decent with modifications12
Overtime natural selection produces organisms that have different structures, established different niches, or occupy different habitats.
Organisms that were once the same have now grown “apart” and have become different organisms.
These changes increase a species’ fitness in their environment.

13. These traits will be passed on to the next generation. 13
THE BASICS: A review
ADAPTATIONS (traits) that are become more prevalent within that population.
These traits will be passed on to the next generation.
The GENE POOL of a population CHANGES in favor of the “FITTEST” phenotype & genotype!!!

14. Environment selecting “good” traits for THAT environment.
Natural
Selection
Examples 14

15. Example: Peppered Moth15
Two versions of the moth-
Black and peppered
During the industrial revolution on England
Population of moths changed

16. the larger birds were favored over the smaller ones
From 1976 through 1977, a severe drought struck an island in the Galapagos. 17
Sampling the birds that died as well as those that survived showed that
the larger birds were favored over the smaller ones
those with larger beaks were favored over those with smaller ones.
of Small beaks
Beak length (mm)
Beak depth (mm)
Dead birds
10.68
9.42
Survivors
11.07
9.96
Some phenotypes are more fit than others when it comes to competing for resources will survive and have the possibility of passing its alleles to the next generation.

17. 18

18. 19

19. History Thomas Malthus -1798-22
Thomas Malthus
Proposed that populations outgrew their food supplies, causing competition between organisms and a struggle for one species to survive against another
This "struggle for existence" drives population change.

20. History Jean-Baptiste Lamark -1809-23
Jean-Baptiste Lamark
Believed that all life forms evolved and that the driving force of evolution was the inheritance of acquired characteristics.
He believed that organisms changed due to the demands of their environment.

21. What we understand now:24
What we understand now:

22. Charles Darwin -1859- Publishes “On the Origin of Species”27
Charles Darwin Publishes “On the Origin of Species”
Believed that Natural Selection is the driving force for evolution.

23. Charles Darwin British Naturalist 1809 -1882 28
“I have called this principle, by which each slight variation, if useful, is preserved, by the term Natural Selection.” —Charles Darwin from "The Origin of Species"

24. From 1831 to 1836 Darwin served as a naturalist aboard the H. M. S
From 1831 to 1836 Darwin served as a naturalist aboard the H.M.S. Beagle on a British science expedition around the world.
In South America Darwin found fossils of extinct animals that were similar to modern species.
On the Galapagos Islands in the Pacific Ocean he noticed many variations among plants and animals of the same general type as those in South America. 29
CLIP

25. Summary of Darwin’s Ideas30
Individual organisms differ, and some of this variation is heritable.
Organisms produce more offspring than can survive, and many that do survive do not reproduce.
Because more organisms are produced than can survive, they compete for limited resources.
Individuals best suited to their environment survive and reproduce most successfully.

26. Summary of Darwin’s Ideas31
These organisms pass their heritable traits to their offspring. Other individuals die or leave fewer offspring.
This process of natural selection causes species to change over time.
Species alive today are descended with modification from ancestral species that lived in the distant past.
This process, by which diverse species evolved from common ancestors, unites all organisms on Earth into a single tree of life.
Review Clip

27. Review Clip: 10min 32
Evidence
Whale Video Clip- Intro to evidence

28. Evidence for Change Over Time33
Fossil Record
Fossils that show how the same organism looked millions of years ago.
Paleontology
Use rock layers
1) Isotope dating
Clip

29. Fossil Record 34

30. 2) Relative Dating 35

31. Homologous structures 37
Structures that have in different organisms but have developed from the same type of tissue.

32. Homologous structures38

33. Analogous versus Homologous Structures

34. 39
Embryology
Early development of the organism

35. 40
Stages of Development