There’s something you need to know… The Origin of Species Mom, Dad… There’s something you need to know… I’m a MAMMAL! 2010-2011

Speciation __________________________________________________________________ Can be slow and gradual or in “bursts” Extinction rates can be rapid and then adaptive radiation follows when new habitats are available

Correlation of speciation to food sources Seed eaters Flower eaters Insect eaters Rapid speciation: new species filling niches, because they inherited successful adaptations. Adaptive radiation

So…what is a species? Population whose members can interbreed & produce viable, fertile offspring ___________________________ Distinct species: songs & behaviors are different enough to prevent interbreeding Humans re so diverse but considered one species, whereas these Meadowlarks look so similar but are considered different species. Meadowlarks Similar body & colorations, but are distinct biological species because their songs & other behaviors are different enough to prevent interbreeding Eastern Meadowlark Western Meadowlark 4

How do new species originate? When two populations become reproductively isolated from each other. Speciation Modes: ___________ geographic separation “other country” _____________ still live in same area “same country”

Allopatric Speciation Physical/geographical separation of two populations _______________________ After a length of time the two population are so different that they are considered different species _________________________interbreeding will still not occur due to pre/post zygotic isolation

Sympatric Speciation Formation of a new species without geographic isolation. Causes: ____________ barriers exist to mating _____________ (only organism with an even number of chromosomes are fertile…speciation occurs quickly) Hybridization: two different forms of a species mate in common ground (hybrid zone) and produce offspring with greater genetic diversity than the parents….eventually the hybrid diverges from both sets of parents

Pre-zygotic Isolation Sperm never gets a chance to meet egg ____________________: barriers prevent mating Ecological isolation: different habitats in same region _____________________: different populations are fertile at different times Behavior Isolation: they don’t recognize each other or the mating rituals ________________: morphological differences Gamete Isolation: Sperm and egg do not recognize each other Sea urchins release sperm & eggs into surrounding waters where they fuse & form zygotes. Gametes of different species— red & purple —are unable to fuse.

Post Zygotic Isolation ______________– the embryo cannot develop inside the mothers womb Hybrid Sterility – Adult individuals can be produced BUT they are not fertile ____________– each successive generation has less fertility than the parental generation Species of salamander genus, Ensatina, may interbreed, but most hybrids do not complete development & those that do are frail. Even if hybrids are vigorous they may be sterile; chromosomes of parents may differ in number or structure & meiosis in hybrids may fail to produce normal gametes Horse(64) x donkey(62) = mule (63 chromosomes) In strains of cultivated rice, hybrids are vigorous but plants in next generation are small & sterile. On path to separate species.

Evolutionary Time Scale _______________ – changing of allele frequencies in a population over time. ______________ – patterns of change over geologic time. Determines phylogeny Gradualism – ______________________ Punctuated equilibrium – periods of massive evolution followed by periods with little to no evolution

What must Earth have been like before living things took over? Origin of the Earth What must Earth have been like before living things took over?

The Primitive Earth Atmosphere: All chemicals/compounds necessary are thought to have originated on earth Inorganic precursors: Water vapor Nitrogen Carbon dioxide Small amounts of hydrogen and carbon monoxide These were the monomers for forming more complex molecules. Experiments have shown that it is possible to form organic from inorganic.

Key Events in Origin of Life Origin of Cells (Protobionts) lipid bubbles  separate inside from outside  metabolism & reproduction Origin of Genetics __________________________ multiple functions: encodes information (self-replicating), enzyme, regulatory molecule, transport molecule (tRNA, mRNA) makes inheritance possible ______________________ Origin of Eukaryotes endosymbiosis Life is defined partly by two properties: accurate replication and metabolism. Neither property can exist without the other. Self–replicating molecules and a metabolism–like source of the building blocks must have appeared together. How did that happen? The necessary conditions for life may have been met by protobionts, aggregates of abiotically produced molecules surrounded by a membrane or membrane–like structure. Protobionts exhibit some of the properties associated with life, including simple reproduction and metabolism, as well as the maintenance of an internal chemical environment different from that of their surroundings. Laboratory experiments demonstrate that protobionts could have formed spontaneously from abiotically produced organic compounds. For example, small membrane–bounded droplets called liposomes can form when lipids or other organic molecules are added to water.

Prokaryotic ancestor of eukaryotic cells First Eukaryotes ~2 bya Development of internal membranes create internal micro-environments _________________________________ natural selection! nuclear envelope endoplasmic reticulum (ER) plasma membrane infolding of the plasma membrane nucleus DNA cell wall plasma membrane Prokaryotic cell Prokaryotic ancestor of eukaryotic cells Eukaryotic cell

internal membrane system 1st Endosymbiosis Evolution of eukaryotes ___________________ ____________________, but did not digest them mutually beneficial relationship natural selection! internal membrane system aerobic bacterium mitochondrion Endosymbiosis Ancestral eukaryotic cell Eukaryotic cell with mitochondrion

photosynthetic bacterium chloroplast & mitochondrion 2nd Endosymbiosis Eukaryotic cell with mitochondrion Evolution of eukaryotes ____________________ engulfed _______________ bacteria, but did not digest them mutually beneficial relationship natural selection! photosynthetic bacterium chloroplast mitochondrion Endosymbiosis Eukaryotic cell with chloroplast & mitochondrion

Theory of Endosymbiosis Evidence structural mitochondria & chloroplasts resemble bacterial structure genetic ______________________________________________________________________________________ functional mitochondria & chloroplasts move freely within the cell mitochondria & chloroplasts reproduce independently from the cell

Evidence Supporting Evolution 2006 Fossil Discovery of Early Tetrapod “Tiktaalik” “missing link” from sea to land animals Evidence Supporting Evolution

Evidence for Evolution Paleontology – fossils show change in a species over time Biogeography – Similar species are found in similar ecosystems around the world Morphology – Comparing structures __________________– body parts with similar structure but possible different function. Shows common ancestry Analogous structures – similar structure develops in organisms that share a common ecosystem but not a common ancestry Biochemical or Molecular - __________________________________

Fossils Preserved remains of living things Paleontology is the study of the fossil record Most organisms do not leave a fossil after death Explains the “missing links” Sedimentation Fossils As the organism decomposes the spaces will be filled with the minerals from the silt

Fossil Evidence of Evolution Fossils are the preserved remains of once-living organisms Rock fossils are created when three events occur _______________________ calcium in bone or other hard tissue mineralizes surrounding sediment hardens to form rock

How old is that fossil? Relative Dating _______________ ____________________________________________ _______________ Age of fossils determined by analyzing the content of radioactive isotopes found in the fossil. Half-life: The length of time required for half of the radioactive elements to change into another stable element. Unaffected by temperature, light, pressure, etc. All radioactive isotopes have a dependable half life. Ex: C14 decays into N14

Patterns of Evolution Divergent Evolution (adaptive radiation) _________________ Is it a shark or a dolphin??

Divergent vs. Convergent Types of EVOLUTION Divergent vs. Convergent

DIVERGENT EVOLUTION __________________________. Think of other words that use the same root word. “Dissect, Divide, Divorce” Could two or more different species have shared a common parental species?

ADAPTIVE RADIATION - In some circumstances, many separate groups will break off from the main population to form their own isolated gene pools. These individual gene pools will undergo their own changes due to Genetic Drift, Mutation and Natural Selection. During these circumstances, many new species may form from one Parental Species. This is known as ADAPTIVE RADIATION

CONVERGENT EVOLUTION __________________________. Think of other words that use the same root word. “Congregate, Concert, Connect” Could two or more different species that look similar and have similar traits, be totally unrelated To one another?

Anatomical Evidence for Evolution Homologous structures: structures with different appearances and functions that all derived from the same body part in a common ancestor The bones in the forelimb of mammals are homologous structures __________________________________

Anatomical Evidence for Evolution Analogous structures: ___________________________________________________________________ Same functions, different ancestor structure

Anatomical Evidence for Evolution Vestigial structures: __________________________, but resemble structures their ancestors possessed Vestigial structures of a whale

Coevolution _______________________________________________________ predator-prey disease & host competitive species mutualism pollinators & flowers