Evolution and Biodiversity Chapter 4

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

How Did We Become Such a Powerful Species So Quickly? Strong opposable thumbs Strong opposable thumbs Walk upright Walk upright Intelligence Intelligence

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) 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.” Biological evolution - first life 3.7 bya (prokaryotes) “Populations - not individuals - evolve by becoming genetically different.”

Animation- Chemical Evolution Stanley Miller's experiment animation

Fig. 4-3, p. 66 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) Biological Evolution of Life

How Do We Know Which Organisms Lived in the Past? How Do We Know Which Organisms Lived in the Past? Fossil record Fossil record Radiometric dating Radiometric dating Ice cores Ice cores DNA studies DNA studies

Biological Evolution Evolution = change in populations genetic makeup over time ( “Populations - not individuals - evolve by becoming genetically different. ”) 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 “Theory” of evolution = All species descended from earlier, ancestral species Microevolution = small genetic changes in a population Microevolution = small genetic changes in a population Macroevolution = long-term, large scale evolutionary changes (speciation, extinction) 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 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 3. Differential Reproduction - individuals w/ trait have more offspring Three Conditions: 1. Genetic Variability 2. Trait must be inherited 3. Differential Reproduction - individuals w/ trait have more offspring

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

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

Adaptive trait interaction Animation

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

Broad and Narrow Niches and Limits of Adaptation Generalist species - broad niche Generalist species - broad niche Specialist species - narrow niche, more extinction- prone under changing environmental conditions. Which is better? Specialist species - narrow niche, more extinction- prone under changing environmental conditions. Which is better? Limits of adaptation- gene pool & reproductive capacity Limits of adaptation- gene pool & reproductive capacity Refer to Spotlight, p. 72- cockroaches

Niche separation Specialist species with a narrow niche Generalist species with a broad niche Niche breadth Region of niche overlap Niches of Specialist and Generalist Species Resource use Number of individuals

Animation Stabilizing selection animation.

Animation Disruptive selection animation.

Specialized Feeding Niches for Birds 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 Piping plover feeds on insects and tiny crustaceans on sandy beaches Fig. 4-10, p. 72

Cockroaches: Nature’s Ultimate Survivors Fig. 4-11, p. 72

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 Evolutionary Divergence of Honeycreepers

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

Speciation What is speciation? What is speciation? Geographic isolation 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 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

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

Speciation on archipelago animation Animation

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

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

PANGAEA GONDWANALAND LAURASIA NORTH AMERICA ANTARTICA AUSTRALIA AFRICA EURASIA SOUTH AMERICA INDIA MADA GASCAR 225 million years ago135 million years ago 65 million years agoPresent Fig. 4-6, p. 66 “Continental Drift” (Plate Tectonics): The Breakup of Pangaea

Mass Extinctions of the Earth’s Past

Terrestrial organisms Marine organisms Quaternary Tertiary Cretaceous Jurassic Triassic Permian Carboniferous Devonian Silurian Ordovician Cambrian Pre-cambrain Number of families Millions of years ago Changes in Biodiversity over Geologic Time

Fig. 4-B, p. 69 Genetically Engineered Mouse Mouse on right has human growth hormone gene- grows 3x faster and 2x larger