Chapter 2.3 Biogeography
What is biogeography? Bio-geography- is the study of where organisms live. Bio- a living thing Geography – Earth or places on Earth
Continental drift One reasons why there are so many species is that continents on Earth move very slowly. Earth has plates that move very slowly for millions of years. A long time ago, there was one continent called “Pangaea” that has split and drifted to different places.
Pangaea Look at the textbook page 55
Continental drift (con’t.) Continental drift had a great impact on the distribution of species. Areas that were isolated long ago developed unique species, but species could disperse across and between continents close to one another.
Australia Millions of years ago Australia drifted way from other landmasses. Over time, animals were isolated for a long time and adapted to the environment and changed into new species- like kangaroo or koala.
Means(ways) of dispersal Dispersal – is a movement of organisms from one place to another HOW? by wind by water by other living things, including humans
By wind and water Wind can help disperse (move) seeds, small spiders, spores of fungi Water can disperse objects that can float in water like coconuts or leaves Small animals may move on the top of floating logs (wood) or rafts
By living things Birds can eat berries and fly somewhere else to leave their seeds in their wastes Your dog or cat can move seeds to other places in their fur Humans can disperse intentionally or unintentionally Insects are moved by airplane Europeans took corn and potatoes from America to Europe
By living things (con’t.) Exotic species – is an organism that is carried into a new location by people
What can limit dispersal? Physical barriers Competition Climate
Physical barriers Water Mountain Desert These features can limit the movement of organisms. Example: Australia drifted away and animals could not move easily from or to Australia.
Competition When organisms enter a new area, they must compete with other animals for food, water and place to live.
Climate Climate – is a the typical weather in an area over a long time Different plants and animals live in different climates. For example: the climate changes dramatically as you move up a tall mountain (textbook pg 57)
Checking concepts: What is a Pangaea? Pangaea is a large landmass that split and moved into different places.
How do animals move to different places? by wind by water by other living things, including humans
How do water help disperse (move) living things? Water can carry coconuts or leaves to different plances Small animals may move on the top of floating logs (wood) or rafts
What are exotic species? Exotic species – is an organism that is carried into a new location by people
What is a continental drift? Continental drift is a process by which the continents move slowly across Earth’s surface.
How do humans disperse species? Humans intentionally or accidentally disperse species as they travel.
What are three ways that will block the dispersal of a species? Physical barriers (water, mountain, desert) Competition Weather
What will happen to a seed that landed on a dry area? The seed will not grow because the dry area has not enough water to feed the seed.
Section 2.3 Assessment 1a. What is continental drift? 1b. How has continental drift affected the dispersal of organisms? 1c. How can continental drift explain why unique species are often found on islands? 2a. What are three ways in which organisms can be dispersed? 2b. What role do humans play in the dispersal of species?
Assessment con’t. 2c. Do you think the role of humans in the dispersal of species will increase or decrease in the next 50 years? Defend your answer. 3a. What are three factors that can limit the dispersal of a species? 3b. Suppose that a new species of insect were introduced to your area. How might competition limit its dispersal?