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Lecture 4`

Lecture 4`. Evolution, Biodiversity, and Population Ecology. What will I learn today?. What is evolution Discuss your feeling about evolution Learn examples of biodiversity Learn basics of ecology necessary to understand environmental biology. Costa Rican Cloud Forest. Case study

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Lecture 4`

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  1. Lecture 4` Evolution, Biodiversity, and Population Ecology

  2. What will I learn today? • What is evolution • Discuss your feeling about evolution • Learn examples of biodiversity • Learn basics of ecology necessary to understand environmental biology

  3. Costa Rican Cloud Forest Case study There one year and gone the next!

  4. Monteverde cloud forest

  5. Golden toads of Costa Rica

  6. What happened? • Science wants to know the truth based on sound principles • Were the frogs hunted to death? • Were the frogs eaten by predators? • Were the frogs killed by a disease? • Did they leave the region? • Did they become something else? • Were they caught and sold to the pet trade? • ???? What else ????

  7. Scientific Analysis By looking over the data… conclusions could be drawn.

  8. Environment kills! • In late 1960’s lots of these frogs • The forests were moist and had lots of cloud cover • In late 1990’s all the frogs were extinct! • The forests were drier and there was little cloud cover • Something has caused a change in the climate…

  9. 1960’s 1990’s

  10. Global Warning The death of the frogs has been linked to the warming of the oceans and the resulting deflection of the clouds, reducing the amount of moisture. Frogs needs moisture to live. Actually, the real answer now is that the increased temperatures at night and lower temperatures in the day promote a fungus to grow and kill the frogs! This is our first example of GLOBAL WARMING killing species - remember!

  11. Evolution Introduction to evolution… Evolution by natural selection is one of the best-supported and most illuminating concepts in all of science, yet it has remained socially controversial among some nonscientists who fear it threatens their religious beliefs.

  12. What is evolution? • In the strict sense it is: “Change over time” Rivers change direction over time Mountains form and erode over time • Biological evolution is: “Change in the genetic information over generations” We will understand this over the course of the course…

  13. Evolution is our best supported scientific theory • LAYMAN - a theory is a hunch, a guess, a shot in the dark! • SCIENTIST - a theory is something well supported by evidence. • Watch this great definition of a scientific theory

  14. How are there so many life forms on Earth? • About 1.5 million plus species known • Expect to find up to 100 million • All arose due to Evolution • How? • By process of speciation…

  15. Many possible ways One method is by physical isolation:

  16. DNA damage • What causes the DNA to change? • Many factors alter DNA… • Cosmic radiation • Copying errors during DNA replication • Cellular heat • Chemicals in the environment • Any changes have to pass to offspring to be classified as evolution…

  17. Natural Selection • More babies are born than can be supported by the environment • Each baby is slightly different from the others in the population • Some are better suited to that environment over others • These survive and the others do not… • This video provides a great explanation

  18. Examples of Evolution • Selective breeding by humans • Dogs from wolf • Crops from weeds

  19. Microbes & real-time evolution • The time it takes for large creatures to evolve is very long. • However, since the discovery of microbes we can see evolution in action… • The video, about TB, provides and excellent example

  20. Massive death • The Earth has seen 5 mass extinction in the past • Each killed off between 50% to 95% of species alive at the time • Permian period 250 million years ago • Global warming • K-T event 5 million years ago • Killed the dinosaurs and was caused by a meteor impact

  21. Round 6 has started • Today we are seeing another round • Caused by humans • Population growth issues • Development • Resource depletion • Relocations • Species loss is forever!

  22. God and Evolution • Naturally, science is now trying to understand where we came from, who we are, and why? • These questions and the answers impinge on other human values… • This video presents an opinion on this topic

  23. Biodiversity

  24. Biodiversity • Biodiversity - refers to the sum total of all organisms in an area. • Species - is a particular type of organism that can freely breed and produce fertile offspring. • Population -is a group of individuals of a particular species that live in the same area.

  25. Ecology • Habitat - specific environment in which an organism lives • Both living and non-living parts • Niche - a habitat supplying the factors necessary for the existence of an organism or species • No two species can share the same exact niche - one will go extinct!

  26. Populations follow rules • Understanding these is important in predicting the future. • Age structure diagrams (age pyramids) can tell us how that population will develop in the future…

  27. The shape of the graph is very important

  28. Population demographics • Another key measure is growth rate • The rate of growth of a population is measured using this formula • (Crude birth rate + immigration rate) - (Crude death rate + emigration rate) = Growth rate • Thus, a growth rate of 6/1,000 would be expressed as: 6/1,000 × 100% = 0.6%

  29. Exponential Growth • A population that increases by a fixed percentage each year is said to exhibit exponential growth This form of growth cannot be sustained for long. Something (food, shelter, space, waste) will change it.

  30. Carrying capacity • Every population eventually is constrained by limiting factors, physical, chemical, and biological characteristics of the environment that restrain population growth. • The interaction of these factors determines the carrying capacity • the maximum population size of a species that a given environment can sustain.

  31. Carrying Capacity

  32. As we have seen, the global human population has risen from fewer than 1 billion 200 years ago to 6.7 billion today, and we have far exceeded our historic carrying capacity. What accounts for the increase in Earth’s carrying capacity for us? Do you think there are limiting factors for the human population? What might they be? Do you think we can keep raising our carrying capacity in the future? Might Earth’s carrying capacity for us decrease?

  33. Conclusions You may appreciate evolution theory a bit more. The evolutionary processes of natural selection, speciation, and extinction help determine Earth’s biodiversity. Understanding how ecological processes work at the population level is crucial to protecting biodiversity threatened by the mass extinction event that many biologists maintain is already underway.

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