ENVIRONMENTAL SCIENCE CHAPTER 4: Biodiversity and Evolution

Core Case Study: Why Are Amphibians Vanishing? (1) Habitat loss and fragmentation Prolonged drought Increased ultraviolet radiation Parasites Viral and fungal diseases

Core Case Study: Why Are Amphibians Vanishing? (2) Pollution Climate change Overhunting Nonnative predators and competitors 33% of all amphibian species face extinction

Fig. 4-1, p. 61

4-1 What Is Biodiversity and Why Is It Important? Concept 4-1 The biodiversity found in genes, species, ecosystems, and ecosystem processes is vital to sustaining life on earth.

Biodiversity (1) Species diversity A set of individuals that can mate and produce fertile offspring 8-100 million species total; likely 10-14 million 2 million species identified ~50% in endangered tropical rainforests

Biodiversity (2) Genetic diversity Ecosystem diversity Biomes Distinct climate Certain species, especially vegetation Functional diversity

Fig. 4-2, p. 61

these types of biodiversity? Functional Diversity The biological and chemical processes such as energy flow and matter recycling needed for the survival of species, communities, and ecosystems. Ecological Diversity The variety of terrestrial and aquatic ecosystems found in an area or on the earth. Active Figure 4.2: Natural capital: the major components of the earth’s biodiversity—one of the earth’s most important renewable resources (Concept 4-1). See an animation based on this figure at CengageNOW. Question: Give two examples of how people, in their daily living, intentionally or unintentionally degrade each of these types of biodiversity? Genetic Diversity The variety of genetic material within a species or a population. Species Diversity The number and abundance of species present in different communities Fig. 4-2, p. 61

Fig. 4-3, p. 61

Fig. 4-4, p. 63

Coastal mountain ranges Sierra Nevada Great American Desert Rocky Average annual precipitation 100-125 cm (40-50 in.) 75-100 cm (30-40 in.) 50-75 cm (20-30 in.) 25-50 cm (10-20 in.) below-25 cm (0-10 in.) Denver Baltimore San Francisco St. Louis Las Vegas Coastal mountain ranges Sierra Nevada Great American Desert Rocky Mountains Great Plains Mississippi River Valley Appalachian Mountains Figure 4.4: Major biomes found along the 39th parallel across the United States. The differences reflect changes in climate, mainly differences in average annual precipitation and temperature. Coastal chaparral and scrub Coniferous forest Desert Coniferous forest Prairie grassland Deciduous forest Fig. 4-4, p. 63

Science Focus: Insects Around for ~400 million years Bad reputation Useful to humans and ecosystems Vital roles in sustaining life Pollinators Natural pest control Renewing soils

Fig. 4-A, p. 62

Fig. 4-A, p. 62

4-2 How Does the Earth’s Life Change over Time? Concept 4-2A The scientific theory of evolution explains how life on earth changes over time through changes in the genes of populations. Concept 4-2B Populations evolve when genes mutate and give some individuals genetic traits that enhance their abilities to survive and to produce offspring with these traits (natural selection).

Theory of Evolution Fossils Mineralized and petrified remains Skeletons, bones, and shells Leaves and seeds Impressions in rocks Fossil record incomplete: ~1% of all species Charles Darwin, On the Origin of Species, 1859

Population Changes over Time Populations evolve by becoming genetically different over time Genetic variability – mutations Random changes in DNA molecules in genes Can occur spontaneously External agents: radiation Can create a heritable trait

Natural Selection Adaptive traits - genetically favorable traits that increase the probability to survive and reproduce Trait – heritable and lead to differential reproduction Faced with environmental change Adapt through evolution Migrate Become extinct

Evolution through Natural Selection Summarized Genes mutate, individuals are selected, and populations evolve such that they are better adapted to survive and reproduce under existing environmental conditions.

Fig. 4-5, p. 65

and eventually (d) replace all or most of the nonresistant bacteria. A group of bacteria, including genetically resistant ones, are exposed to an antibiotic Most of the normal bacteria die The genetically resistant bacteria start multiplying Eventually the resistant strain replaces all or most of the strain affected by the antibiotic Figure 4.5: 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. Normal bacterium Resistant bacterium Fig. 4-5, p. 65

and eventually (d) replace all or most of the nonresistant bacteria. A group of bacteria, including genetically resistant ones, are exposed to an antibiotic Normal bacterium Resistant bacterium Eventually the resistant strain replaces the strain affected by the antibiotic The genetically resistant bacteria start multiplying Most of the normal bacteria die Figure 4.5: 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. Stepped Art Fig. 4-5, p. 83

Adaptation through Natural Selection Has Limits Humans unlikely to evolve and have skin that’s not harmed by UV radiation Desired trait must already be in the gene pool. Must have high reproductive capacity so adaptive traits can be spread rapidly

Three Myths about Evolution through Natural Selection Refuted “Survival of the fittest” does not mean “survival of the strongest” Organisms don’t develop traits just because they would be useful: giraffes and long necks There is no grand plan of nature to create more perfectly adapted species – no trend toward genetic perfection

Science Focus: How Did We Become Such a Powerful Species? Key adaptations – also enabled us to modify environment Opposable thumbs Walk upright Complex brains Transmit ideas to others Develop technologies to alter environment Technology dominates earth’s life support systems and NPP

4-3 How Do Geological Processes and Climate Changes Affect Evolution? Concept 4-3 Tectonic plate movements, volcanic eruptions, earthquakes, and climate change have shifted wildlife habitats, wiped out large numbers of species, and created opportunities for the evolution of new species.

Plate Tectonics Locations of continents and oceans determine earth’s climate Movement of continents allow species to move and adapt Earthquakes and volcanoes affect biological evolution by separating populations of a species and allowing new species to develop

Fig. 4-6, p. 66

an area of land splitting apart cause the extinction of a species? 225 million years ago 135 million years ago 65 million years ago Present Figure 4.6: 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). About 180 million years ago, Pangaea began splitting apart as the earth’s tectonic plates separated, eventually resulting in today’s locations of the continents (bottom). Question: How might an area of land splitting apart cause the extinction of a species? Fig. 4-6, p. 66

225 million years ago 135 million years ago Present 65 million years ago Figure 4.3: 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 land areas split apart and also in the rise of new species when once isolated land areas combine. Rock and fossil evidence indicates that 200–250 million years ago all of the earth’s present-day continents were locked together in a supercontinent called Pangaea (top left). About 180 million years ago, Pangaea began splitting apart as the earth’s huge plates separated, and their movements eventually resulted 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? Stepped Art Fig. 4-6, p. 66

Earth’s Long-Term Climate Changes Cooling and warming periods – affect evolution and extinction of species Change ocean levels and area Glaciers expanding and contracting Climate changes Opportunities for the evolution of new species Many species go extinct

Fig. 4-7, p. 67

Northern Hemisphere Ice coverage Legend 18,000 years before present Northern Hemisphere Ice coverage Modern day (August) Legend Continental ice Sea ice Land above sea level Figure 4.7: Changes in ice coverage in the northern hemisphere during the past 18,000 years. (Data from the National Oceanic and Atmospheric Administration) Fig. 4-7, p. 67

Science Focus: Earth is Just Right for Life to Thrive Life needs a temperature range that results in liquid water Earth’s orbit: right distance from sun Earth’s optimal gravity: keeps atmosphere Favorable temperature range over earth history has promoted evolution and biodiversity Favorable oxygen level in atmosphere

4-4 How Do Speciation, Extinction, and Human Activities Affect Biodiversity? Concept 4-4 Human activities decrease the earth’s biodiversity by causing the premature extinction of species and by destroying or degrading habitats needed for the development of new species.

Speciation Speciation Geographic isolation Reproductive isolation One species splits into two or more species that can no longer breed and produce fertile offspring Geographic isolation Reproductive isolation

Fig. 4-8, p. 68

Arctic Fox Northern population Early fox population Gray Fox Southern Adapted to cold through heavier fur, short ears, short legs, and short nose. White fur matches snow for camouflage. Arctic Fox Northern population Spreads northward and southward and separates Early fox population Different environmental conditions lead to different selective pressures and evolution into two different species. Gray Fox Adapted to heat through lightweight fur and long ears, legs, and nose, which give off more heat. Southern population Figure 4.8: Geographic isolation can lead to reproductive isolation, divergence of gene pools, and speciation. Fig. 4-8, p. 68

Science Focus: Changing Genetic Traits Artificial selection Selective breeding: crossbreeding varieties within same species to enhance desired traits Grains, fruits, vegetables, dogs, other animals Genetic engineering Add, delete, or alter DNA segments Add desirable genes from other species New drugs, pest-resistant plants Controversial

Extinction (1) Biological extinction Local extinction Entire species gone Local extinction All members of a species in a specific area gone Endemic species vulnerable to extinction Background extinction Speciation generally more rapid than extinction

Extinction (2) Mass extinction Earth took millions of years to recover from previous mass extinctions Balance between speciation and extinction determines biodiversity of earth Humans cause premature extinction of species

Human Activities and Extinction Cause premature extinction of species

4-5 What Is Species Diversity and Why Is It Important? Concept 4-5 Species diversity is a major component of biodiversity and tends to increase the sustainability of some ecosystems.

Species Diversity Species richness Species evenness Varies with geographic location Species richness declines towards poles

Richness and Sustainability Hypothesis Does a community with high species richness have greater sustainability and productivity? Research suggests “yes”

4-6 What Roles Do Species Play in an Ecosystem? Concept 4-6 Each species plays a specific ecological role called its niche.

Ecological Niche (1) Species occupy unique niches and play specific roles in an ecosystem Includes everything required for survival and reproduction Water Sunlight Space Temperatures Food requirements

Ecological Niche (2) Generalist species Specialist species Native species Nonnative species Spread in new, suitable niches

Fig. 4-10, p. 72

competition and allows sharing of limited resources. Ruddy turnstone searches under shells and pebbles for small invertebrates Herring gull is a tireless scavenger Brown pelican dives for fish, which it locates from the air Avocet sweeps bill through mud and surface water in search of small crustaceans, insects, and seeds Dowitcher probes deeply into mud in search of snails, marine worms, and small crustaceans Black skimmer seizes small fish at water surface Flamingo feeds on minute organisms in mud Figure 4.10: Specialized feeding niches of various bird species in a coastal wetland. This specialization reduces competition and allows sharing of limited resources. Louisiana heron wades into water to seize small fish Oystercatcher feeds on clams, mussels, and other shellfish into which it pries its narrow beak Piping plover feeds on insects and tiny crustaceans on sandy beaches Scaup and other diving ducks feed on mollusks, crustaceans, and aquatic vegetation Knot (sandpiper) picks up worms and small crustaceans left by receding tide Fig. 4-10, p. 72

Science Focus: Cockroaches Existed for 350 million years – 3,500 known species Highly adapted, rapidly producing generalists Consume almost anything Endure food shortage Survive everywhere except polar regions Avoid predation Carry human diseases

Fig. 4-11, p. 72

Indicator Species Early warning system Fish Birds Butterflies Amphibians

Fig. 4-12, p. 74

predators and competitors. Adult frog (3 years) Young frog Tadpole develops into frog Sperm Sexual reproduction Tadpole Figure 4.12: Life cycle of a frog. Populations of various frog species can decline because of the effects of harmful environmental factors at different points in their life cycle. Such environmental factors include habitat loss, drought, pollution, increased UV radiation, parasitism, disease, overhunting for food (frog legs), and nonnative predators and competitors. Eggs Fertilized egg development Egg hatches Organ formation Fig. 4-12, p. 74

Keystone Species Significant role in their food web: large affect on types and abundances of other species in an ecosystem Elimination may alter structure and/or function of ecosystem Pollinators Top predators

Foundation Species Create habitats and ecosystems Beavers Elephants Seed dispersers

Science Focus: American Alligator Highly adaptable Only natural predator is humans 1967 – endangered species list Successful environmental comeback Keystone species

Case Study: Why Should We Protect Sharks? Remove injured, sick animals Many are gentle giants Provide potential insight into cures for human diseases such as cancer Keystone species Hunted and killed by humans

Three Big Ideas from This Chapter - #1 Populations evolve when genes mutate and give some individuals genetic traits that enhance their abilities to survive and to produce offspring with these traits (natural selection).

Three Big Ideas from This Chapter - #2 Human activities are decreasing the earth’s vital biodiversity by causing the premature extinction of species and by disrupting habitats needed for the development of new species.

Three Big Ideas from This Chapter - #3 Each species plays a specific ecological role in the ecosystem where it is found (ecological niche).

Animation: Carbon Bonds

Animation: Stanley Miller’s Experiment

Animation: Evolutionary Tree of Life

Animation: Stabilizing Selection

Animation: Disruptive Selection

Animation: Moth Populations

Animation: Adaptive Trait

Animation: Speciation on an Archipelago

Animation: Evolutionary Tree Diagrams

Animation: Gause’s Competition Experiment

Animation: Species Diversity By Latitude

Animation: Humans Affect Biodiversity

Animation: Habitat Loss and Fragmentation

Animation: Transferring Genes into Plants

Video: Ancient Human Skull PLAY VIDEO

Video: Asteroid Menace PLAY VIDEO

Video: Bachelor Pad at the Zoo PLAY VIDEO

Video: Cloned Pooch PLAY VIDEO

Video: Creation vs. Evolution PLAY VIDEO

Video: Dinosaur Discovery PLAY VIDEO

Video: Glow-in-the-Dark Pigs PLAY VIDEO

Video: Hsing Hsing Dies PLAY VIDEO

Video: Mule Clones PLAY VIDEO

Video: New Species Found PLAY VIDEO

Video: Penguin Rescue PLAY VIDEO