Biodiversity and Evolution Chapter 4

Core Case Study: Why Should We Care about the American Alligator? Largest reptile in North America 1930s: Hunters and poachers Importance of gator holes and nesting mounds 1967: endangered species 1977: comeback, threatened species

Concepts What is biodiversity and why is it important? Where do species come from? How do geological processes and climate change affect evolution? How do speciation, extinction and human activities affect biodiversity? What is species diversity and why is it important? What roles do species play in ecosystems?

4-1 What Is Biodiversity and Why Is It Important? 1) Biodiversity is crucial a) What is it? (Know these) includes species, genetic, ecological and functional diversity b) Biodiversity is a part of natural capital, that keeps us alive c) Preserves air and water quality and soil fertility

Figure 4.2: Natural capital. This diagram illustrates the major components of the earth’s biodiversity—one of the earth’s most important renewable resources and a key component of the planet’s natural capital (see Figure 1-4, p. 9). See an animation based on this figure at CengageNOW. Question: What role do you play in such degradation? Fig. 4-2, p. 82

4-2 Where Do Species Come From? 1) Evolution: Changes in the genes of a population overtime. 2) Darwin and Wallace are credited for the theory of Natural Selection as the process leading to evolution 3) Darwin wrote On the Origin of Species by Means of Natural Selection in 1850.

Biological Evolution by Natural Selection Explains How Life Changes over Time 4) Basic ideas a) Species constantly struggle to survive b) Those best suited to the environment survive and reproduce c) The trait is then passed to the next generation, increasing the occurrence of that trait in the population d) Tree of life (the kingdoms of living things as a result of evolution pg 81) (Still many unanswered questions & scientific debate)

5) The Fossil Record Tells Much of the Story of Evolution a) What is a fossil? (also found in polar ice) b) Fossil record: all fossils collected through out the world, it is uneven and incomplete c) Some forms do not leave fossils and other fossils have decomposed.

Figure 4.6: This fossilized skeleton is the mineralized remains of an herbivore that lived during the Cenozoic era from 26 to 66 million years ago. Fig. 4-6, p. 86

6) The Genetic Makeup of a Population Can Change a) Populations, not individual, evolve by becoming genetically different. b) Mutation: random changes in DNA leading to genetic diversity c) Mutations are accidental during mitosis or caused by mutagens d) Only those in reproductive cells can be passed on to next generation

b) Adaptation (adaptive trait): above 7) Individuals in Populations with Beneficial Genetic Traits Can Leave More Offspring a) Natural selection can only occur if individuals have a trait that increases their chance of survival, that can be passed on . b) Adaptation (adaptive trait): above c) Differentiated reproduction: selection for organisms with a specific trait d) Genetic resistance: ability to tolerate a chemical designed to kill it: (antibiotic resistance)

Figure 4. 7: Evolution by natural selection Figure 4.7: Evolution by natural selection. (a) A population of bacteria is exposed to an antibiotic, which (b) kills all individuals except those possessing a trait that makes them resistant to the drug. (c) The resistant bacteria multiply and eventually (d) replace all or most of the nonresistant bacteria. Fig. 4-7, p. 87

b) When the environment changes adapt, migrate or become extinct 8) Evolution Summary a) Genes mutate, individuals are selected, and populations evolve that are better adapted to survive and reproduce b) When the environment changes adapt, migrate or become extinct (Read case study page 83)

9) Adaptation through Natural Selection Has Limits a) Trait must already exist in the population’s gene pool b) Reproductive capacity: takes many generations for slow reproducing organisms 10) Common myths a) Survival of fittest means strongest b) occurs because the organism needs or wants them c) There is a grand plan of nature

4-3 How Do Geological Processes and Climate Change Affect Evolution? 1) Geological Processes affect natural selection a) The earth surface move on tectonic plates b) 2 effects 1. the location of continents & ocean basins influence climate 2. has allowed species to move, adapt and form new species 2) Earthquakes: can isolate populations leading to new species

Figure 4.8: Over millions of years, the earth’s continents have moved very slowly on several gigantic tectonic plates. This process plays a role in the extinction of species, as continental areas split apart, and also in the rise of new species when isolated island areas such as the Hawaiian Islands and the Galapagos Islands are created. Rock and fossil evidence indicates that 200–250 million years ago, all of the earth’s present-day continents were connected in a supercontinent called Pangaea (top left). About 180 million years ago, Pangaea began splitting apart as the earth’s tectonic plates moved, eventually resulting in the present-day locations of the continents (bottom right). Question: How might an area of land splitting apart cause the extinction of a species? www.learner.org/resources/series209.html Fig. 4-8, p. 89

3) Climate change & Catastrophes a) Over time the climate has changed leading to “ice ages” and warming periods b) Some species became extinct as the climate changed quickly c) Catastrophic events (asteroids) cause widespread destruction and extinction

Figure 4.9: These maps of the northern hemisphere show the large-scale changes in glacial ice coverage during the past 18,000 years. Other smaller changes in glacial ice on mountain ranges such as the European Alps are not shown. Question: What are two characteristics of an animal and two characteristics of a plant that natural selection would have favored as these ice sheets (left) advanced? (Data from the National Oceanic and Atmospheric Administration) Fig. 4-9, p. 89

1) How do new species evolve? a) Speciation: formation of new species 4-4 How Do Speciation, Extinction, and Human Activities Affect Biodiversity? 1) How do new species evolve? a) Speciation: formation of new species b) Geographic isolation usually causes speciation c) Reproductive isolation: occurs when organisms will no longer mate forming a new species. d) For most organisms this is very slow

Figure 4.10: Geographic isolation can lead to reproductive isolation, divergence of gene pools, and speciation. Fig. 4-10, p. 91

2) Extinction is Forever a) Endemic species are found only in 1 place and are more susceptible to extinction Golden toad of Costa Rica became extinct because of global warming

Extinction Can Affect One Species or Many Species at a Time b) Background extinction: low rate extinction c) Mass extinction: large groups of species become extinction (3 or 5 show in fossil record depending on definition) d) New species can fill in the niches left by mass extinction. e) Humans are increasing extinction rate

Science Focus: We Have Two Ways to Change the Genetic Traits of Populations Artificial selection Genetic engineering, gene splicing Consider Ethics Morals Privacy issues Harmful effects

4-5 What Is Species Diversity and Why Is It Important? a) Richness: number of different species b) Evenness: the number of members of each species

Species Diversity: Variety, Abundance of Species in a Particular Place 2) Geographical location: diversity decreases from tropics toward poles 3) Most diverse: tropical rain forests, coral reefs, ocean bottom zone and tropical lakes 4) Read species richness on islands pg 90 5) Richness tends to be more productive and have increased stability

4-6 What Roles Do Species Play in Ecosystems? 1) Niche: the role the organism plays in the ecosystem 2) Generalist: broad niche, live in many places, eat a variety of food, tolerate a wide range of conditions 3) Specialist: narrow niche, opposite 4) Which is more likely to become extinct? 5) Which is better depends on consistency of an ecosystem

Figure 4.13: Specialist species such as the giant panda have a narrow niche (left) and generalist species such as the raccoon have a broad niche (right). Fig. 4-13, p. 95

Case Study: Cockroaches: Nature’s Ultimate Survivors Generalists High reproductive rates Giant panda and tiger salamanders Specialists Low reproductive rates

6) Niches Can Be Occupied by Native and Nonnative Species a) Niches can be classified by the role 1. Native: normally live there 2. Nonnative (invasive, exotic alien) don’t 3. Indicator: provide early warnings 4. Keystone: have a large effect on other species in the ecosystem 5. Foundation: shapes communities by creating and enhancing their habitats to benefit other species

Case Study: Why Are Amphibians Vanishing? (1) Habitat loss and fragmentation Prolonged drought Pollution Increase in UV radiation Parasites Viral and fungal diseases Climate change Overhunting Nonnative predators and competitors

Case Study: Why Should We Protect Sharks? Keystone species Eat dead and dying fish in the ocean Strong immune systems Wounds do not get infected Almost never get cancer Could help humans if we understood their immune system

Figure 4.14: This diagram illustrates the specialized feeding niches of various bird species in a coastal wetland. This specialization reduces competition and allows sharing of limited resources. Fig. 4-14, p. 96