Agenda: Hardy Weinberg Lab Hardy Weinberg Quiz Speciation Notes Objective: I can explain what speciation is and the different types. Agenda: Hardy Weinberg Lab Hardy Weinberg Quiz Speciation Notes Speciation Activity Exit ticket

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 Changes in allele frequency are so great that a new species is formed ____________________________ 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 5

How do new species originate? When two populations become reproductively isolated from each other. Speciation Modes: ____________ geographic separation __________ still live in same area

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 _________________________________________________________________________

Sympatric Speciation Formation of a new species without geographic isolation. Causes: ___________________________ Polyploidy (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

Sympatric Speciation Gene flow has been reduced between flies that feed on different food varieties, even though they both live in the same geographic area.

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.

PRE-Zygotic barriers Obstacle to mating or to fertilization if mating occurs geographic isolation ecological isolation temporal isolation behavioral isolation mechanical isolation gametic isolation

Post Zygotic Isolation Hybrid Inviability – __________________________________________ Hybrid Sterility – Adult individuals can be produced BUT they are not fertile Hybrid Breakdown – 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 Microevolution – changing of allele frequencies in a population over time. Macroevolution – patterns of change over geologic time. Determines phylogeny __________ – species are always slowly evolving Punctuated equilibrium – periods of massive evolution followed by periods with little to no evolution

Mass Extinctions At least 5 mass extinctions have occurred throughout history. Possible causes: dramatic climate changes occurring after meteorite collisions and/or continents drift into new and different configurations.

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 makes natural selection & evolution 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 advantage: specialization = increase efficiency 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 _____________________ engulfed aerobic bacteria, 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 origin of chloroplasts engulfed photosynthetic bacteria, but did not digest them _____________________ natural selection! photosynthetic bacterium chloroplast mitochondrion Endosymbiosis Eukaryotic cell with chloroplast & mitochondrion

Theory of Endosymbiosis Evidence structural mitochondria & chloroplasts resemble bacterial structure genetic mitochondria & chloroplasts have their own circular DNA, like bacteria functional _______________________ mitochondria & chloroplasts reproduce independently from the cell

Cambrian explosion Diversification of Animals (545 million years ago) within 10–20 million years most of the major phyla of animals appear in fossil record 543 mya