The Diversity of Life on Earth: Exploring Biodiversity and its Threats

1. KEY CONCEPT Biology is the study of all forms of life.

2. biosphere = everywhere life exists Earth is home to an incredible diversity of life. • Diversity = a wide variety of things. Biodiversity means the wide variety of living creatures on the planet. • The biosphere includes all living things and all the places they are found.

3. Earth is home to an incredible diversity of life. • Every part of the biosphere is connected with every other part. How are they connected? • The biosphere includes many environments. • Both land & water environments: list examples!

4. Tidepool Estuary • saltwater and freshwater environments • The biosphere includes many environments. • portions of the atmosphere also have living things, so it’s also part of the biosphere

5. A species is one particular type of living thing. • Members of a species can interbreed to reproduce. • There are about 2 million different living species have been identified. Their abdomens are filled with sweet nectar! Fat Ants!

6. Biodiversity is the variety of life. • Biodiversity means the number of kinds of organisms (the number of species in an area) • Ecosystems with high biodiversity are considered more healthy than ecosystems with only a few types of creatures • Biodiversity generally increases from the poles to the equator. (The tropics have more kinds of critters than the poles.) • Biodiversity is greater in areas with consistently warm temperatures. Biodiversity is greater closer to the equator.

7. Which environment has greater biodiversity? • Which group of organisms is the most diverse? The least? • Which group of vertebrates is the most diverse? • The desert has 10,000 bats living in it, but only 1,000 bats live in the jungle. All the desert bats are in the same species, but there are 3 different kinds of bats in the jungle. Which environment has a greater diversity of bats?

8. Types of biodiversity Species Diversity The number of different kinds of organisms in an area. (NOT the number of organisms in an area – that would mean the population, not the diversity). This is the usual type of biodiversity discussed by scientists and other people.

9. Types of biodiversity • Genetic Diversity = the number of different kinds of genes in a group of organisms. If there is low genetic diversity, the organisms suffer from inbreeding. This is a problem for endangered species like cheetahs.

10. Types of biodiversity • Ecosystem Diversity = the number of different habitats in an area. More habitats allow greater species diversity, since there are more options for organisms’ survival.

11. Types of biodiversity • Functional Diversity = the variety of ecological processes & natural services that occur in an area, such as nutrient cycling, air purification, pest control, water storage, soil formation….

13. Types of biodiversity F E G S

14. Threats to Biodiversity • Many species have gone extinct recently, and many more are endangered (likely to go extinct) • Once a species is extinct, it is gone forever! • When a species goes extinct, other species that depend on it for food, shelter, etc. are more likely to go extinct too, because all life depends on other living things

15. Causes of Extinctions • In the past, many different kinds of events caused extinctions, including ice ages, volcanic activity, and comets striking the Earth.

16. Causes of Extinctions • The main causes of extinction today include: habitat destruction by people, humans bringing non-native species into a region, hunting and poaching, pollution, and global warming

17. Mass Extinctions 1 • Normally, extinctions occur continuously at a rate that is known as the background rate of extinction – maybe a few species per century, as shown by the fossil record. • A “mass extinction” event occurs when the rate of extinction increases dramatically – maybe a few thousand species per century. • These extinctions seem to be caused by a variety of dramatic events: comet impacts, long-lasting volcanic eruptions, the beginning or ending of ice ages, even massive “burps” of methane that had been stored in ocean sediments. These all seem related to widespread changes in climate.

18. Mass Extinctions 2 • There are five major mass extinctions in the geologic record. • The most famous was the death of the dinosaurs, with strong evidence that it was caused by a comet striking the Earth near what is now the Yucatan peninsula of Mexico 65 million years ago. • The greatest mass extinction was at the end of the Permian period, 225 million years ago. Over 90% of all ocean organisms died! Plus tons o’ land critters! This opened a variety of niches, which allowed the dinosaurs to evolve and rule the globe for millions of years.

20. Evidence for the Comet that Killed the Dinosaurs A thin layer of sediments rich in iridium is found sandwiched between Cretaceous sediments (from dino time) and Tertiary rocks (right after dino death). Iridium is uncommon on Earth, but it is found in higher percentages in meteors, and the iridium layer is found in many locations across the globe. A crater of the correct age (65 mya) has been found on the edge of the Yucatan peninsula. Most of it is underwater. They have also found signs of an ancient tidal wave far inland in the southern US.

21. Mass Extinctions 3 • Many scientists argue that we are now in the sixth mass extinction event in Earth’s history. This is based on analyzing the number of organisms that have gone extinct since Europeans started colonizing other continents. These extinctions have occurred MUCH faster than background extinction rates. As our population continues to grow, and our demand for resources increases, and our production of pollutants increases, and our modification of habitats spreads far and wide, and, oh yeah, as we modify the climate, we can expect these human-caused extinctions to increase even more. Sad….

22. Extinction rates over time • Extinction is a natural process, but humans have increased the number of extinctions much beyond natural levels