Download presentation
Presentation is loading. Please wait.
Published byWilla Hodge Modified over 9 years ago
1
How do organisms adapt and change over time?
2
Charles Darwin (1809-1882) Sailed around the world 1831-1836
3
Galapagos Turtles
5
Darwin’s Travels Revealed The diversity of living species was far greater than anyone had previously known! These observations led him to develop the theory of evolution.
6
Natural Selection The process by which plants and animals with favorable traits survive and reproduce. Occur because of a mutation in the DNA or the environment. Ex. Organisms adapt to their environment.
7
Natural Selection is NOT Selective Breeding! Nature provides variation, humans select variations that are useful. Ex a farmer breeds only his best livestock
8
Natural Selection The traits that help an organism survive in a particular environment are “selected” in natural selection.
9
Example of Natural Selection Peppered MothsDarwin’s Finches The isolation of the birds on an island caused the finches to develop lots of different kinds of beaks. A study on different colored moths disappearing and appearing in an area.
13
Summary of Natural Selection 1. Organisms differ; variation is inherited. 2. Organisms produce more offspring than survive. 3. Organisms compete for resources. 4. Organisms with advantages survive to pass those advantages to their children.
14
Examples of Beneficial Traits: Mimicry Physically or actively looking like another organism. Ex. A walking stick insect.
15
Monarch Butterfly
16
Coral Snake
17
"Red on yellow, kill a fellow. Red on black, won't hurt Jack."
18
How do organisms ensure the survival of there species?
19
Natural Selection Must Haves: Overproduction of offspring (children) Inherited variation or differences Struggle to survive Successful reproduction
20
Possible Reasons for Natural Selection Variation In Genes Competition Pollution/Mutations Environmental Changes Separation Adaptation Division
21
What is a theory? A way to explain something in nature. Usually accepted by the scientific community. May or may not be true.
22
Different types of evolution? Micro-evolution –Changing of an organism within its kind –Basically the same thing as natural selection Macro-evolution Long-term change from one organism to another
23
Both involve change over a period of time. The BIG difference: –Micro-evolution has been observed to happen. –Macro-evolution has not.
24
Things used as evidence for macro-evolution:
25
Fossil Records Are solid remains or imprints of once-living organisms. Are formed from layers of sediment and minerals replacing bone.
27
Relative Dating Can determine a fossil’s relative age Performed by estimating fossil age compared with that of other fossils Drawbacks – provides no info about age in years
28
Absolute Dating Can determine the absolute age in numbers Is performed by radioactive dating – based on the amount of remaining radioactive isotopes remain Drawbacks - part of the fossil is destroyed during the test
29
Carbon-14 Dating
30
What do fossil records and skeletal records show Similarities!
31
Vestigial Structures Structures that do not appear to have a use. Ex. The hind-limb bones deeply embedded inside the whale.
32
Can you find the vestigial structure?
33
Homologous Structures Similar structures in different organisms. Ex. Bones See pg. 156
34
Homologous Body Structures
35
Embryonic Structures Embryos of vertebrates are not the same but look similar. (And, grow into different organisms.) Pg. 157
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.