Unit 5: Evolution Notes

Unit 5: Evolution of Living Things 5.0 Fossils provide evidence of earlier life. 5.1 Scientists use the information in rocks and fossils to learn about the changes in life on Earth.

5. 2 The first living things appeared on Earth about 3 5.2 The first living things appeared on Earth about 3.8 billion years ago. 5.3 The first living things on Earth were single-celled organisms that lived in the ocean called cyanobacteria.

5.4 The earliest life forms were Prokaryotes. 5.5 Prokaryotes: a single-celled organism without a nucleus. 5.6 Eukaryotes: a single or multicellular organism with a nucleus.

5.7 The first animals were jellyfish. 5.8 For most of the history of life on Earth, life existed only in the ocean. 5.9 The first animals on land were insects.

5.10 Extinction: is the loss of all the members of one type of animal. 5.11 Mass Extinction: One of several periods in Earth’s history when large numbers of different animals become extinct at nearly the same time.

5.12 Mass Extinctions may be caused by volcanoes or by asteroid impacts.

5.13 Biological Evolution: is the process by which animals change over time. 5.14 Biological evolution is the result of changes in genetic material (DNA). 5.15 The changes in DNA are passed on from one generation to the next.

5.16 Charles Darwin: was a naturalist who studied evolution and developed an explanation for the process which he called natural selection. 5.17 Charles Darwin published the book: The Origins of Species. This book was about his 5 year journey around the world describing his observations and collections about nature.

5.18 Natural Selection: the process in which individuals with certain traits survive and reproduce more than individuals without these traits.

5.19 Population: is a group of individuals of the same species that live in a particular area. 5.20 Overproduction: is the process in nature where organisms usually produce more offspring that their environment can support. Example: Fish lay thousands of eggs.

5.21 Genetic Variation: Differences in DNA in a population. 5.22 Genetic Variation comes from the mix of DNA from both parents. **Just think are you exactly like your brother or sister? Everyone is a little different.

5.23 Adaptation: An inherited trait that gives an organism an advantage in its environment. Example: A fish tail to swim faster. A long bird beak to get food.

5.24 Environmental Factors: Conditions that affect survival, such as food, predators, and disease. 5.25 Animals with an adaptation useful in their environment have a good chance of living long enough to reproduce and pass on their DNA to offspring.

5.26 Speciation: The evolution of a new animal from an existing animal. 5.27 Darwin’s observations studied how the isolation of populations may lead to the rise of new species or animals. 5.28 When populations are too genetically different to reproduce, they are considered to be different animals.

5.29 Population size is limited by environmental conditions. 5.30 Populations increase through births and immigration. 5.31 Immigration: is the movement of individuals into a population.

5.32 Many factors limit population size such as deaths or emigration. 5.33 Emigration: is the movement of individuals out of a population.

5.34 Limiting Factor: a factor or condition that prevents the continuing growth of a population. 5.35 These factors include food, water, space, shelter, predators, storms, or fires.

5.36 Competition: is a contest between individuals or animals for a location and resources. 5.37 Competition occurs naturally between living organisms which live in the same environment. Example: Animals compete over water, food, and mates.

5.38 Predator: An organism that lives by eating other organisms. 5.39 Disease: is an abnormal condition of an organism that destroys bodily functions.

5.40 Catastrophic Events: is an event that causes large destruction and kill lots of organisms. Example: Fires, Earthquakes, Floods 5.41 The survival of a species depends on its ability to adapt to change.

5.42 The extinction of one animal allows room for another animal to live better. 5.43 Extinction is apart of the cycle of life on Earth.

5.44 Scientific Theory: An explanation about the natural world that is based on a wide range of scientific evidence. 5.45 Scientific Theories are widely accepted by scientists around the world.

Evidence to Support Evolution 5.46 The theory of evolution is supported by many types of evidence including: fossil evidence, biological evidence, and genetic evidence.

Fossil Evidence 5.47 The fossil record shows the history of life on Earth and the evolution of modern animals. 5.48 Ancestor: An early form of an organism from which later forms evolve. 5.49 Scientist use fossils to compare how different animals looked throughout time.

Biological Evidence 5.50 Biological similarities among animals give evidence that animals evolved from a common ancestor. 5.51 Some animals share similar organs and bones, which could mean they came from a common ancestor.

5.52 Vestigial Organs: are structures that were fully developed in ancestral organisms but are small and unused in later animals. Example: Whales have tiny leg bones.

5.53 Comparative Anatomy: The study of the similarities and differences of the physical structures of animals. 5.54 Different animals may have similar structures but use the structures in different ways.

5.55 Embryo: is an animal in an early stage of development. 5.56 The study of embryos show that animals that look very different as adults are similar during early development.

Genetic Evidence 5.57 Scientists compare DNA between different animals. The closer the DNA demonstrates that the animals are more closely related and share a common ancestor.