EVOLUTION Chapter 16

What is evolution? The process of change over time

Charles darwin Born in England February 12th, 1809 (same day as Abraham Lincoln!) Developed a scientific theory of biological evolution that explains how modern organisms evolved over long periods of time through descent of common ancestors

HMS Beagle 1831 Five year voyage Darwin planned to collect specimens of plants and animals

Observations aboard the beagle Species varied globally Species varied locally Species vary over time Observations aboard the beagle

What was Charles Darwin’s contribution to science? Key questions What was Charles Darwin’s contribution to science? What three patterns of biodiversity did Darwin note?

Found flightless, ground-dwelling birds Species vary globally Found flightless, ground-dwelling birds Rheas- South America Ostriches- Africa Emu- Australia Darwin noticed that different, yet similar, animals inhabited different, ecologically similar, habitats around the globe

Species vary locally Different, yet related, animal species occupied different habitats within a local area Galapagos Islands Close to one another but have very different ecological conditions Tortoises’ shells varied in predictable ways from one island to the other Hood Island Tortoise Shells are curved and open, long neck and legs Isabella Island Tortoise Dome-shaped shells, short necks

“ This wonderful relationship in the same continent between the dead and the living, will, I do not doubt, hereafter throw more light on the appearance of organic beings on our earth, and their disappearance from it, than any other class of facts.” – Charles Darwin Species vary over time Some fossils of extinct animals were similar to living species

Darwin found fossils of many organisms that did not resemble any living species. How might this finding have affected his understanding of life’s diversity?

16.2– Ideas that changed Darwin’s thinking

An ancient, changing earth James Hutton and Charles Lyell Geologists in Darwin’s time Concluded that Earth is extremely old and that the processes that changes Earth in the past are the same processes that operate in the present

Hutton and geological change Realized the connection between a number of geological processes and geological features Proposed that forces beneath Earth’s surface can push rock layers upward Mountain ranges Deep Time- the idea that our planet’s history stretched back over a period of time so long that it’s difficult for the human mind to imagine

Population growth Thomas Malthus Darwin connected Malthus’s ideas overcrowding of human population War, famine, and disease Darwin connected Malthus’s ideas Why don’t other species survive for several generations?

Population growth cont. Why was this realization important? Darwin was convinced that species evolved Needed a scientific explanation to explain how and why evolution occurred …Which organisms survive, and why?

16.3 – Darwin presents his case http://media.hhmi.org/biointeractive/interactivevideo/finchquiz/?_ga=2.233966298.538147384.1520437616-1917288444.1520437616 16.3 – Darwin presents his case

The struggle for existence Darwin realized that if more individuals are produced than can survive, members of a population must compete to obtain food, living space, and other limited necessities The struggle for existence

Variation Individuals have natural variations among their heritable traits Some variants suited life better than others Predators with longer claws, sharp teeth, and quick= more prey Camouflage for prey species = avoid being caught

adaptation Adaptation Any heritable characteristic that increases an organisms ability to survive and reproduce in its environment Can involve body parts or structures, colors, or physiological functions

The scarlet king snake is exhibiting mimicry– an adaptation in which an organism copies, or mimics, a more dangerous organism. Although the scarlet king snake is harmless, it looks like the poisonous eastern coral snake, so predators avoid it too.

scorpion fish A scorpionfish’s coloring is an example of camouflage– an adaptation that allows an organism to blend into its background and avoid predation.

Adaptations of behavior Adaptations often involve many systems and even behavior. Here, a crane is displaying a defensive behavior in an effort to scare off the nearby fox.

Survival of the fittest Fitness How well an organism can survive and reproduce in its environment High fitness Individuals with adaptations that are well suited to their environment can survive and reproduce Low fitness Individuals with characteristics that are not well suited to their environment either die without reproducing or leave few offspring