BIODIVERSITY & EVOLUTION CHAPTER 4 BIODIVERSITY & EVOLUTION

Three Big Ideas 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). Human activities are decreasing the earth’s vital biodiversity by causing the extinction of species and by disrupting habitats needed for the development of new species. Each species plays a specific ecological role (ecological niche) in the ecosystem where it is found.

Biodiversity Is a Crucial Part of the Earth’s Natural Capital Species: set of individuals who can mate and produce fertile offspring 8 million to 100 million species 1.9 million identified Unidentified are mostly in rain forests and oceans Biodiversity Is a Crucial Part of the Earth’s Natural Capital

Classifying Homo Sapiens Figure 2 This diagram illustrates the taxonomic classification of the latest human species, Homo sapiens sapiens.

Natural Capital: Major Components of the Earth’s Biodiversity 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?

Coastal mountain ranges Mississippi River Valley Major Biomes Denver Baltimore San Francisco Las Vegas St. Louis Coastal mountain ranges Sierra Nevada Great American Desert Rocky Mountains Great Plains Mississippi River Valley Appalachian Mountains Coastal chaparral and scrub Coniferous forest Desert Prairie grassland Deciduous forest Figure 4.5: The major biomes found along the 39th parallel across the United States are shown in this diagram. The differences in tree and other plant species reflect changes in climate, mainly differences in average annual precipitation and temperature.

Biological Evolution by Natural Selection Explains How Life Changes over Time Fossils Physical evidence of ancient organisms Reveal what their external structures looked like Fossil record: entire body of fossil evidence Only have fossils of 1% of all species that lived on earth

Fossilized Skeleton of an Herbivore that Lived during the Cenozoic Era 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

Biological evolution: how earth’s life changes over time through changes in the genetic characteristics of populations Darwin: Origin of Species Natural selection: individuals with certain traits are more likely to survive and reproduce under a certain set of environmental conditions Verification: huge body of evidence Biological Evolution by Natural Selection Explains How Life Changes over Time

Evolution of Life on Earth Figure 1 This diagram provides an overview of the evolution of life on the earth into six major kingdoms of species as a result of natural selection. Supplement 5, Fig. 2, p. S18

Evolution by Natural Selection Works through Mutations and Adaptations Populations evolve by becoming genetically different from other populations Genetic variations First step in biological evolution Occurs through mutations in reproductive cells Mutations: random changes in DNA molecules Evolution by Natural Selection Works through Mutations and Adaptations

Evolution by Natural Selection Works through Mutations and Adaptations Natural selection: acts on individuals Second step in biological evolution Adaptation may lead to differential reproduction Genetic resistance: ability of one or more members of a population to resist a chemical designed to kill it

Evolution by Natural Selection Fig. 4-7, p. 87 (a) A group of bacteria, including genetically resistant ones, are exposed to an antibiotic (b) Most of the normal bacteria die (c) The genetically resistant bacteria start multiplying (d) Eventually the resistant strain replaces all or most of the strain affected by the antibiotic Normal bacterium Resistant bacterium 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.

Adaptation through Natural Selection Has Limits Adaptive genetic traits must precede change in the environmental conditions Reproductive capacity Species that reproduce rapidly and in large numbers are better able to adapt “Survival of the fittest” is not necessarily “survival of the strongest” Organisms do not develop traits out of need or want No grand plan of nature for perfect adaptation Adaptation through Natural Selection Has Limits

Geologic Processes Affect Natural Selection Tectonic plates affect evolution and the location of life on earth Locations of continents and oceans have shifted Species physically move, or adapt, or form new species through natural selection Earthquakes Volcanic eruptions

Movement of the Earth’s Continents over Millions of Years 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? Fig. 4-8, p. 89

225 million years ago 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? Fig. 4-8, p. 89

135 million years ago 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? Fig. 4-8, p. 89

65 million years ago 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? Fig. 4-8, p. 89

Present 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? Fig. 4-8, p. 89

225 million years ago 135 million years ago 65 million years ago Present Stepped Art Fig. 4-8, p. 89

Climate Change and Catastrophes Affect Natural Selection Ice ages followed by warming temperatures Collisions between the earth and large asteroids New species Extinctions

Changes in Ice Coverage in the Northern Hemisphere During the last 18,000 Years 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

How Do New Species Evolve? Speciation: one species splits into two or more species Reproductive isolation: mutations and natural selection in isolated populations lead to inability to produce viable offspring when members of two different populations mate Geographic isolation: one mechanism of reproductive isolation; happens first; requires physical isolation of populations for a long period How Do New Species Evolve?

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

Extinction is Forever Extinction Biological extinction Local extinction Endemic species Found only in one area Particularly vulnerable Background extinction: ongoing; low rate of extinction Mass extinction: rapid and devastating; 3-5 times over 500 million years

Changing the Genetic Traits of Populations Artificial selection Use selective breeding/crossbreeding Genetic engineering, gene splicing Consider Ethics Morals Privacy issues Harmful effects

Artificial Selection Figure 4.C: Artificial selection involves the crossbreeding of species that are close to one another genetically. In this example, similar fruits are being crossbred. Fig. 4-C, p. 92

Genetically Engineered Mice Figure 4.D: These mice are an example of genetic engineering. The 6-month-old mouse on the left is normal; the same-age mouse on the right had a human growth hormone gene inserted into its cells. Mice with this gene grow two to three times faster than, and twice as large as, mice without it. Question: How do you think the creation of such species might change the process of evolution by natural selection? Fig. 4-D, p. 92

Species Diversity: Variety, Abundance of Species in a Particular Place Species diversity is a combination of: 1. Species richness: The number of different species in a given area 2. Species evenness: Comparative number of individuals

Species Diversity: Variety, Abundance of Species in a Particular Place Diversity varies with geographical location The most species-rich communities Tropical rain forests Coral reefs Ocean bottom zone Large tropical lakes

Species-Rich Ecosystems Tend to Be Productive and Sustainable Species richness seems to increase productivity and stability or sustainability, and provide insurance against catastrophe How much species richness is needed is debatable

Each Species Plays a Unique Role in Its Ecosystem Ecological niche, niche Pattern of living: everything that affects survival and reproduction Water, space, sunlight, food, temperatures Generalist species Broad niche: wide range of tolerance Specialist species Narrow niche: narrow range of tolerance

Specialist Species and Generalist Species Niches 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

Specialized Feeding Niches of Various Bird Species in a Coastal Wetland Herring gull is a tireless scavenger Brown pelican dives for fish, which it locates from the air Ruddy turnstone searches under shells and pebbles for small invertebrates 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 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. Flamingo feeds on minute organisms in mud Scaup and other diving ducks feed on mollusks, crustaceans, and aquatic vegetation Louisiana heron wades into water to seize small fish Oystercatcher feeds on clams, mussels, and other shellfish into which it pries its narrow beak Knot (sandpiper) picks up worms and small crustaceans left by receding tide Piping plover feeds on insects and tiny crustaceans on sandy beaches Fig. 4-14, p. 96

Species Can Play Five Major Roles within Ecosystems Native species Nonnative species Indicator species Keystone species Foundation species

Indicator Species Serve as Biological Smoke Alarms Provide early warning of damage to a community Can monitor environmental quality Trout Birds Butterflies Frogs

Keystone Species Play Critical Roles in Their Ecosystems Keystone species: roles have a large effect on the types and abundances of other species Pollinators Top predators

Foundation Species Help to Form the Bases of Ecosystems Create or enhance their habitats, which benefit others Elephants Beavers