Evolution and Biodiversity Chapter 4

Key Concepts Origins of life Evolution and evolutionary processes Ecological niches Species formation Species extinction

How Did We Become Such a Powerful Species So Quickly? Strong opposable thumbs Walk upright Intelligence Fig. 4-1, p. 63

Origin & Evolution of Life Chemical evolution - 1st billion yrs organic molecules, biopolymers & chemical rxns needed for formation of first cells (Age of Earth = 4.6 billion years) Biological evolution - first life 3.7 bya (prokaryotes) “Populations - not individuals - evolve by becoming genetically different.”

Animation- Chemical Evolution Stanley Miller's experiment animation

Biological Evolution of Life Modern humans (Homo sapiens) appear about 2 seconds before midnight Recorded human history begins 1/4 second before midnight Origin of life (3.6–3.8 billion years ago) Fig. 4-3, p. 66

How Do We Know Which Organisms Lived in the Past? Fossil record Radiometric dating Ice cores DNA studies Fig. 4-2, p. 65

Biological Evolution Evolution= change in populations genetic makeup over time (“Populations - not individuals - evolve by becoming genetically different.”) “Theory” of evolution= All species descended from earlier, ancestral species Microevolution= small genetic changes in a population Macroevolution= long-term, large scale evolutionary changes (speciation, extinction)

Natural Selection Definition: Process where particular beneficial trait is reproduced in succeeding generations more than other traits Three Conditions: 1. Genetic Variability 2. Trait must be inherited (selection occurs) 3. Differential Reproduction - individuals w/ trait have more offspring

Adaptations Structural- coloration, mimicry, protective, gripping Physiological - hibernate, chemical Behavioral - ability to fly, migrate

Animation Change in moth population animation “Genes mutate, individuals are selected, and populations evolve.”

Animation Adaptive trait interaction

Ecological Niches and Adaptation Ecological niche = occupation (role) Habitats = address Fundamental niche = no competition Realized niche = with competition

Specialized Feeding Niches for Birds Herring gull is a tireless scavenger Brown pelican dives for fish, which it locates from the air Black skimmer seizes small fish at water surface 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 Scaup and other diving ducks feed on mollusks, crustaceans, and aquatic vegetation Flamingo feeds on minute organisms in mud Knot (a sandpiper) picks up worms and small crustaceans left by receding tide 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 Louisiana heron wades into water to seize small fish Fig. 4-5, p. 68-69

Broad and Narrow Niches and Limits of Adaptation Generalist species - broad niche Specialist species - narrow niche, more extinction-prone under changing environmental conditions. Which is better? Limits of adaptation- gene pool & reproductive capacity Refer to Spotlight, p. 69- cockroaches

Niches of Specialist and Generalist Species Specialist species with a narrow niche Generalist species with a broad niche Niche separation Number of individuals Niche breadth Region of niche overlap End Pt 1 Resource use Fig. 4-4, p. 68

Stabilizing selection animation.

Disruptive selection animation.

Evolutionary Divergence of Honeycreepers Unknown finch ancestor Fruit and seed eaters Insect and nectar eaters Greater Koa-finch Kona Grosbeak Akiapolaau Maui Parrotbill Kuai Akialaoa Crested Honeycreeper Apapane Amakihi Fig. 4-6, p. 70

Misconceptions of Evolution “Survival of the fittest” OK if: Fitness = reproductive success ≠ strongest “Progress to perfection”

Speciation What is speciation? Geographic isolation Reproduction isolation mutation & natural selection operate independently in gene pools of geographically isolated populations original populations become genetically distinct- unable to produce live, fertile offspring

Geographic Isolation can Lead to Speciation Arctic Fox Adapted to cold through heavier fur, short ears, short legs, short nose. White fur matches snow for camouflage. 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 Fig. 4-7, p. 71

Animation Speciation on archipelago animation

Extinctions Background extinctions= 1-5 species per million Mass extinctions- five previous mass extinctions: 25% - 75% species go Mass depletions- > background, but < mass Human impacts - 6th major mass extinction???

Mass Extinctions of the Earth’s Past Fig. 4-9, p. 73

Factors Leading to Extinction Plate tectonics Climatic changes over time-most Natural catastrophes Human impacts

“Continental Drift” (Plate Tectonics): The Breakup of Pangaea GONDWANALAND LAURASIA NORTH AMERICA ANTARTICA AUSTRALIA AFRICA EURASIA SOUTH AMERICA INDIA MADA GASCAR 225 million years ago 135 million years ago 65 million years ago Present Fig. 4-8, p. 72

Changes in Biodiversity over Geologic Time 1600 Terrestrial organisms Silurian Devonian Permian Triassic Jurassic 1200 Cambrian Ordovician Cretaceous Pre-cambrain Carboniferous Marine organisms Number of families 800 Tertiary Quaternary 400 3500 545 500 440 410 355 290 250 205 145 65 1.8 Millions of years ago Fig. 4-10, p. 74

Future of Evolution Artificial selection (selective breeding) Genetic engineering (gene splicing) Genetic modified organisms (GMOs) Cloning Ethical concerns

Genetically Engineered Mouse Mouse on right has human growth hormone gene- grows 3x faster and 2x larger Fig. 4-12, p. 76

Genetic Engineering Links Genetic Engineering and Society, Lecture 1a, Honors Collegium 70A, UCLA http://www.youtube.com/watch?v=eg19FquatGo Watch This Lecture. Take Notes and turn in for 10 activity points Yale University online Lectures- Genetic Engineering http://www.youtube.com/watch?v=uUddHabtAzk&feature=relmfu Alternative to UCLA lecture. Future of genetic engineering - by Futurist Dr Patrick Dixon. http://www.youtube.com/watch?v=P_UoReSgz84