4-1: Biodiversity and Evolution

Transcription

1 4-1: Biodiversity and Evolution After this lecture you should be able to Explain the importance of biological diversity to an ecosystem. Classify species based on taxonomic categories. Explain how evolution works to increase biodiversity. Identify ways in which humans impact biological diversity.

2 Gotta Catch em All! Why are there so many Pokémon?

3 Biodiversity: What is it? Biological Diversity refers to the variety of life- forms in an area. It is commonly expressed in terms of the number of species or gene?c types/varia?ons within the community A QUICK REVIEW: Species: A group of organisms that are capable of interbreeding to produce offspring. Popula?on: A group of individuals of the same species in the same area. Community: A collec?on of different popula?ons (different species) in the same area. Ecosystem: All of the interac?ng, living and non- living components within a specific area.

4 Biodiversity Basics Biodiversity includes: Gene?c Diversity The number of gene?c characteris?cs of a species Includes sub- species, groups, breeds, and varia?ons. Habitat Diversity The different kinds of habitats (loca?ons where a species can exist.) Species Diversity Species Richness (number of different species) Species Evenness (abundance of species/number of individuals of a species) Species Dominance (the most abundant species)

5 Species Diversity The number of different species is not an accurate measure of biodiversity. Describe the diagrams above in terms of species richness, evenness, and dominance.

6 Taxonomic Classification Members of different species may have similar traits as each other. Biologists classify species based on these similari?es, which are recognized as evolu?onary rela?onships. The modern classifica?on system for all living things is based on grouping species into categories (or Taxa) based on their similari?es, then separa?ng them into other taxa based on their differences.

7 A History Lesson: Evolution In the 1830 s, a Bri?sh scien?st named Charles Darwin was traveling on the HMS Beagle in the Galapagos Islands. He was amazed and the diverse and unique organisms that he observed. He also noted that despite their diversity, almost all of the organisms had certain commonali?es. Darwin s Theory of Evolu?on concludes that species have the ability to change over?me, and those changes can become so varied that new species can be formed as a result of these changes. Furthermore, he was convinced that these organisms must have some ancestral link in their past.

8 Biological Evolution Organisms depend on each other and their environment for survival. If the environmental condi?ons change an organism has 3 op?ons: Migrate: Go to a place where the environmental condi?ons are more favorable. Adapt: Change pa\erns of behavior to respond to the new environment. Die: If an organism is unable to adapt to its environment or move to an environment in which it can survive then it will die. (IMPORTANT: Dead organisms do not reproduce.) Darwin proposed that organisms evolved as a result of natural selec?on. This is a process by which organisms with favorable traits survive longer and reproduce more. This has o^en been described as survival of the fi\est. Misconcep)on: Survival of the fi\est means survival of the strongest.

9 The Forces Behind N.S. There are 4 main factors that drive natural selec?on: Overproduc?on: A species has more offspring than can survive to reproduc?ve maturity. Gene?c Varia?on: The individuals in a popula?on have different traits ranging from color & size to strength& speed. Struggle to Survive: Individuals compete against each other for limited resources. Differen?al Reproduc?on: The organisms that survive due to their fitness for the environment reproduce and pass the favorable traits to their offspring.

10 Speciation Specia?on occurs when two species arise from one, in response to changes in environmental condi?ons. This can be accomplished by: Geographic isola?on Reproduc?ve isola?on Geographic isola?on occurs when a species or two groups of the same popula?on become physically separated for long periods. The result is some?mes referred to Allopatric Specia?on. Reproduc?ve isola?on occurs as muta?on and natural selec?on (survival of the fi\est) work independently in two geographically isolated popula?ons. The result is some?mes referred to as Sympatric Specia?on.

11 The Value of Biodiversity Instrumental value: a species or organism s existence or use benefits some other en?ty Food, raw materials, medicine, economics, recrea?onal, scien?fic Usually anthropocentric: beneficiaries are humans Ecological capital and value to the ecosystem (equilibrium) We preserve species to enjoy the benefits they provide Intrinsic value: something has value for its own sake It does not have to be useful to us Do animals have rights? Or are they simply property?

12 Human Impacts on Biodiversity Why is it going the wrong way?

13 End of Lecture Objectives Explain the importance of biological diversity to an ecosystem. Classify species based on taxonomic categories. Explain how evolution works to increase biodiversity. Identify ways in which humans impact biological diversity.