Chapter 4 Evolution and Biodiversity

Core Case Study Earth: The Just-Right, Adaptable Planet  3.7 billion years since life arose  average surface temperature of the earth has remained within the range of o C Figure 4-1

ORIGINS OF LIFE  1 billion years of chemical change to form the first cells, followed by about 3.7 billion years of biological change. Figure 4-2

Animation: Stanley Miller’s Experiment PLAY ANIMATION

Fig. 4-3, p. 84 Modern humans (Homo sapiens sapiens) appear about 2 seconds before midnight Recorded human history begins about 1/4 second before midnight Origin of life ( billion years ago) Age of mammals Age of reptiles Insects and amphibians invade the land First fossil record of animals Plants begin invading land Evolution and expansion of life

Animation: Evolutionary Tree of Life PLAY ANIMATION

How Do We Know Which Organisms Lived in the Past?  Our knowledge about past life comes from: Fossils Fossils chemical analysis chemical analysis cores drilled out of buried ice cores drilled out of buried ice DNA and protein analysis DNA and protein analysis Figure 4-4

EVOLUTION, NATURAL SELECTION, AND ADAPTATION  Biological evolution by natural selection change in a population’s genetic makeup through successive generations change in a population’s genetic makeup through successive generations genetic variability genetic variability Mutations: Mutations: random changes in the structure or number of DNA molecules in a cell that can be inherited by offspring.random changes in the structure or number of DNA molecules in a cell that can be inherited by offspring.

Animation: Stabilizing Selection PLAY ANIMATION

Natural Selection and Adaptation: Leaving More Offspring With Beneficial Traits  Three conditions are necessary for biological evolution: Genetic variability Genetic variability traits must be heritable traits must be heritable trait must lead to differential reproduction trait must lead to differential reproduction An adaptive trait is any heritable trait that enables an organism to survive through natural selection and reproduce better under prevailing environmental conditions.An adaptive trait is any heritable trait that enables an organism to survive through natural selection and reproduce better under prevailing environmental conditions. Survival of the Fittest Survival of the Fittest

Animation: Disruptive Selection PLAY ANIMATION

Animation: Moth Populations PLAY ANIMATION

Animation: Adaptive Trait PLAY ANIMATION

Hybridization and Gene Swapping: other Ways to Exchange Genes  Hybridization Can create new species Can create new species Occurs when individuals to two distinct species crossbreed to produce fertile offspring Occurs when individuals to two distinct species crossbreed to produce fertile offspring  Some species (mostly microorganisms) can exchange genes without sexual reproduction. Horizontal gene transfer Horizontal gene transfer

Limits on Adaptation through Natural Selection  Changes are limited by the population’s gene pool and how fast it can reproduce. Humans have a relatively slow generation time (decades) and output (# of young) versus some other species. Humans have a relatively slow generation time (decades) and output (# of young) versus some other species.

Common Myths about Evolution through Natural Selection  Organisms do not develop certain traits because they need them.  There is no such thing as genetic perfection.

GEOLOGIC PROCESSES, CLIMATE CHANGE, CATASTROPHES, AND EVOLUTION  movement of solid (tectonic) plates causes: volcanic eruptions volcanic eruptions earthquakes earthquakes can wipe out existing species and help form new onescan wipe out existing species and help form new ones Species movement/relocation Species movement/relocation locations of continents and oceanic basins influence climate locations of continents and oceanic basins influence climate

Fig. 4-5, p million years ago Present 65 million years ago 225 million years ago

Video: Continental Drift PLAY VIDEO

Climate Change and Natural Selection  Changes in climate throughout the earth’s history have shifted where plants and animals can live. Figure 4-6

Video: Dinosaur Discovery  From ABC News, Environmental Science in the Headlines, 2005 DVD. PLAY VIDEO

Catastrophes and Natural Selection  Catastrophies Asteroids and meteorites hitting the earth Asteroids and meteorites hitting the earth upheavals of the earth from geologic processes upheavals of the earth from geologic processes wipe out large numbers of species wipe out large numbers of species create evolutionary opportunities by natural selection of new species create evolutionary opportunities by natural selection of new species Adaptive radiationAdaptive radiation

ECOLOGICAL NICHES AND ADAPTATION Fundamental niche: Fundamental niche: the full potential range of physical, chemical, and biological conditions and resources a species could theoretically usethe full potential range of physical, chemical, and biological conditions and resources a species could theoretically use Realized niche: Realized niche: to survive and avoid competition, a species usually occupies only part of its fundamental nicheto survive and avoid competition, a species usually occupies only part of its fundamental niche

Generalist and Specialist Species: Broad and Narrow Niches  Generalist species tolerate a wide range of conditions species tolerate a wide range of conditions  Specialist species can only tolerate a narrow range of conditions species can only tolerate a narrow range of conditions Figure 4-7

SPOTLIGHT Cockroaches: Nature’s Ultimate Survivors  350 million years old  3,500 different species  Ultimate generalist Can eat almost anything Can eat almost anything Can live and breed almost anywhere Can live and breed almost anywhere Can withstand massive radiation Can withstand massive radiation Figure 4-A

Specialized Feeding Niches  Resource partitioning reduces competition reduces competition allows sharing of limited resources allows sharing of limited resources Figure 4-8

Fig. 4-8, pp Piping plover feeds on insects and tiny crustaceans on sandy beaches (Birds not drawn to scale) Black skimmer seizes small fish at water surface Flamingo feeds on minute organisms in mud Scaup and other diving ducks feed on mollusks, crustaceans,and aquatic vegetation 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 Louisiana heron wades into water to seize small fish Oystercatcher feeds on clams, mussels, and other shellfish into which it pries its narrow beak Dowitcher probes deeply into mud in search of snails, marine worms, and small crustaceans Knot (a sandpiper) picks up worms and small crustaceans left by receding tide Herring gull is a tireless scavenger Ruddy turnstone searches under shells and pebbles for small invertebrates

Video: Frogs Galore  From ABC News, Environmental Science in the Headlines, 2005 DVD. PLAY VIDEO

Evolutionary Divergence  Each species has a beak specialized to take advantage of certain types of food resource. Figure 4-9

SPECIATION, EXTINCTION, AND BIODIVERSITY  Speciation: A new species can arise when member of a population become isolated for a long period of time. A new species can arise when member of a population become isolated for a long period of time. Genetic makeup changes, preventing them from producing fertile offspring with the original population if reunitedGenetic makeup changes, preventing them from producing fertile offspring with the original population if reunited Reproductive Isolation Reproductive Isolation

Animation: Speciation on an Archipelago PLAY ANIMATION

Animation: Evolutionary Tree Diagrams PLAY ANIMATION

Geographic Isolation  …can lead to reproductive isolation, divergence of gene pools and speciation. Figure 4-10

Extinction: Lights Out  Extinction occurs when the population cannot adapt to changing environmental conditions occurs when the population cannot adapt to changing environmental conditions  The golden toad of Costa Rica’s Monteverde cloud forest has become extinct because of changes in climate. Figure 4-11

Fig. 4-12, p. 93 Tertiary Bar width represents relative number of living species EraPeriod Species and families experiencing mass extinction Millions of years ago Ordovician: 50% of animal families, including many trilobites. Devonian: 30% of animal families, including agnathan and placoderm fishes and many trilobites Cambrian Ordovician Silurian Devonian Extinction Paleozoic Mesozoic Cenozoic Triassic: 35% of animal families, including many reptiles and marine mollusks. Permian: 90% of animal families, including over 95% of marine species; many trees, amphibians, most bryozoans and brachiopods, all trilobites. Carboniferous Permian Current extinction crisis caused by human activities. Many species are expected to become extinct within the next 50–100 years. Cretaceous: up to 80% of ruling reptiles (dinosaurs); many marine species including many foraminiferans and mollusks. Extinction Triassic Jurassic Cretaceous Extinction QuaternaryToday

Effects of Humans on Biodiversity  The scientific consensus is that human activities are decreasing the earth’s biodiversity. Figure 4-13

GENETIC ENGINEERING AND THE FUTURE OF EVOLUTION  artificial selection Used to change the genetic characteristics of populations with similar genes through selective breeding Used to change the genetic characteristics of populations with similar genes through selective breeding  genetic engineering  Used to transfer genes from one species to another  Human to bacteria Figure 4-15

Genetic Engineering: Genetically Modified Organisms (GMO)  GMOs  use recombinant DNA genes or portions of genes from different organisms. genes or portions of genes from different organisms. Figure 4-14

Fig. 4-14, p. 95 Insert modified plasmid into E. coli Phase 1 Make Modified Gene Cell Extract DNA E. coli Gene of interest DNA Identify and extract gene with desired trait Genetically modified plasmid Identify and remove portion of DNA with desired trait Remove plasmid from DNA of E. coli Plasmid Extract Plasmid Grow in tissue culture to make copies Insert extracted (step 2) into plasmid (step 3)

Fig. 4-14, p. 95 Plant cell Phase 2 Make Transgenic Cell Transfer plasmid to surface of microscopic metal particle Use gene gun to inject DNA into plant cell Agrobacterium inserts foreign DNA into plant cell to yield transgenic cell Transfer plasmid copies to a carrier agrobacterium Nucleus E. Coli A. tumefaciens (agrobacterium) Foreign DNA Host DNA

Fig. 4-14, p. 95 Cell division of transgenic cells Phase 3 Grow Genetically Engineered Plant Transfer to soil Transgenic plants with new traits Transgenic cell from Phase 2 Culture cells to form plantlets

Animation: Transgenic Plants  From ABC News, Biology in the Headlines, 2005 DVD. PLAY ANIMATION

How Would You Vote?  Should we legalize the production of human clones if a reasonably safe technology for doing so becomes available? a. No. Human cloning will lead to widespread human rights abuses and further overpopulation. a. No. Human cloning will lead to widespread human rights abuses and further overpopulation. b. Yes. People would benefit with longer and healthier lives. b. Yes. People would benefit with longer and healthier lives.

THE FUTURE OF EVOLUTION  Cloning rebuild organisms from their cell components rebuild organisms from their cell components has lead to:has lead to: high miscarriage rates high miscarriage rates rapid aging rapid aging organ defects organ defects  Genetic engineering can help improve human condition can help improve human condition results are not always predictable results are not always predictable Do not know where the new gene will be located in the DNA molecule’s structure and how that will affect the organism.Do not know where the new gene will be located in the DNA molecule’s structure and how that will affect the organism.

Video: Cloned Pooch  From ABC News, Biology in the Headlines, 2005 DVD. PLAY VIDEO

Controversy Over Genetic Engineering  There are a number of privacy, ethical, legal and environmental issues.  Should genetic engineering and development be regulated?  What are the long-term environmental consequences?

Case Study: How Did We Become Such a Powerful Species so Quickly?  We lack: strength, speed, agility strength, speed, agility weapons (claws, fangs), protection (shell) weapons (claws, fangs), protection (shell) poor hearing and vision poor hearing and vision  We have thrived as a species because of our: opposable thumbs opposable thumbs ability to walk upright ability to walk upright complex brains (problem solving) complex brains (problem solving)