E VOLUTION E XAM R EVIEW. S PECIES AND P OPULATIONS Species a group of organisms mating between...
-
Upload
elwin-oneal -
Category
Documents
-
view
212 -
download
0
Transcript of E VOLUTION E XAM R EVIEW. S PECIES AND P OPULATIONS Species a group of organisms mating between...
EVOLUTION EXAM REVIEW
SPECIES AND POPULATIONS
Species a group of organisms mating between members of the group occurs
naturally offspring are healthy and fertile
Populations a group of individuals of the same species that
live in a particular area mating occurs between members of the same
population
GENETIC VARIATION
caused by differences in the genetic code of individuals
lots of variation allows for higher success success in biology is described as the ability of a
species to survive and produce healthy offspring sources of variation include mutations and
recombination (synapsis/crossing over)
http://www.dnalc.org/view/15117-Genetic-variations-in-humans-Kenneth-Kidd.html
http://www.dnatube.com/video/685/DNA--Duplication-and-Mutations
NATURE AND ARTIFICIAL SELECTION
Artificial Selection when specific organisms of a species are
bread to emphasize/enhance certain traits breeds of dogs
Natural Selection when certain traits are propagated in a
population due to their ability to increase survival and reproductive ability Darwin’s Finches
ARTIFICIAL SELECTIONADVANTAGES & DISADVANTAGES
Advantages increased food production increase in quality of food domestication pets with “desirable traits” creation of new species
Disadvantages reduced genetic variation loss of biodiversity “desirable traits” can cause reduced fertility and
healthhttp://www.youtube.com/watch?v=bi9Pa0DHG5Y http://www.youtube.com/watch?v=i7kbPsCdyQ0
Important Terms & Concepts
• Gene pool: consists of all the alleles in all the individuals that make up a population
• Sources of variation: 1. Mutation of DNA sequence
2. Sexual reproduction- crossing over/ random assortment
Important Terms & Concepts
• Changes to Gene Pools– Measured using Hardy-Weinberg equilibrium – Equilibrium of a gene pool means it is not evolving
and the frequencies of alleles are constant – Equilibrium will be maintained if:
• Must be random mating • Large population • No movement in or out of the population • No mutations • No natural selection
Types of Evolution• Evolution depends on the selection of favorable
traits• Several factors may disrupt the Hardy-Weinberg
equilibrium, and therefore cause microevolution
• Types of Evolution:– Microevolution – Changes within a population – Macroevolution – The origin of new species (aka
“speciation”)
Mechanisms of Microevolution1. Natural Selection (including Sexual Selection)2. Artificial Selection/ Selective Breeding3. Genetic Drift- The Bottleneck Effect4. Genetic Drift - The Founder Effect5. Gene Flow6. Human Influence
Group Activity - using your notes from Friday, or provided notes, write a point form note on the board and teach the concept to the class Homework p.223 #10, 11, 12, 16
Recall: Types of Evolution• Microevolution – changes
within a population of a particular species
• Macroevolution – changes that produce entirely new species = speciation– Speciation is evident in the
fossil record and can lead to an increase in biodiversity on Earth
Allopatric Speciation• Speciation caused by geographic isolation
1) Great distance between populations• Ancestors migrate to different islands (Galapagos
finches)
Allopatric Speciation (cont)
2) Physical barrier between populations• Isthmus of Panama divides Pacific Ocean and
Caribbean Sea • Formation of Rocky Mountains created
different environmental conditions on either side
• Human influence
http://www.youtube.com/watch?v=ATWE2Y5uOMw
http://www.youtube.com/watch?v=YCoEiLOV8jc
Sympatric Speciation
• A new species evolves within a large population; the new species coexist in the same environment.1) Gradual: Due to changes in behaviour
• Hawthorn flies vs Apple Flies
Sympatric Speciation (cont)2) Sudden: Due to mutation or polyploidy
• Polyploidy – organisms of the same species with different numbers of chromosomes (2n, 4n, etc.)
• Ontario’s eastern gray treefrog and Cope’s gray treefrog
Ontario variety is tetraploid (4n) while Cope variety is diploid (2n)
Orange day lily is triploid (3n) and produces 3x as many petals as diploid varieties
Patterns in Evolution• Natural selection leads to many predictable
outcomes• On a grander scale, these predictable
outcomes produce recognizable patterns in evolution
(A) Divergent Evolution(B) Convergent Evolution(C) Coevolution
Divergent Evolution
• Divergent evolution is also called adaptive radiation
• A common ancestor gives rise to many different species that each fill a different ecological niche.– Niche: All factors related to the role of an
organism in the environment (predators, prey, habitat, nocturnal/diurnal, etc)
Divergent Evolution (cont)
• Examples:– Ontario rodents– Galapagos finches
Convergent Evolution• Different species that do not share a recent common
ancestor have evolved similar traits because they experience the same selective pressures (analogous features)
Ex. 1 Eyes of spiders and humans
Ex. 2 Streamlined body shape of sharks and dolphins
Coevolution• Two species evolve simultaneously when the survival
of one species is influenced by the other• Examples:
– Predator-Prey: “evolutionary arms race”– Flowering plants and pollinators– Species that rely on mimicry for survival will continue to
evolve if the species they mimic changes
How Did Life Begin?
• Abiogenesis – The first living things arose from non-living matter– Theory initially proposed independently by two
different scientists in 1920’s– Suggested that first life forms arose spontaneously
once the first organic molecules were made in “primordial soup”
*Organic compounds include carbohydrates, fats, protein, and DNA, and are the building blocks of all living things
Young Earth Conditions• Geologic evidence suggests that
the atmosphere contained carbon monoxide, carbon dioxide, nitrogen, methane, hydrogen, ammonia, hydrogen sulfide, and water vapor (but little or no oxygen)– Oxygen is very reactive
• Energy from volcanic eruptions, lightning, and UV radiation would be more intense than they are today
First Cells on Earth• Prokaryotes: cells that do not have membrane-
bound organelles– Heterotrophs: feed on other cells– Chemoautotrophs: Make their own food from simple
inorganic molecules (without light)– Photosynthetic: Make their own food from carbon
dioxide and light (produce oxygen)
• Oxygen would have been toxic, – some cells adapted to survive in O2
– adapted further to using the oxygen for respiration as it accumulated in the atmosphere (aerobic prokaryotes)
Origin of Eukaryotic Cells• Eukaryotic cells have membrane-bound
organelles (including the nucleus) – Believed to have evolved from prokaryotes by inward
folding of cell membrane– Early eukaryotes did not contain mitochondria or
chloroplasts• Endosymbiotic theory: Explains the origin of
chloroplasts and mitochondria:– Early eukaryotes ingested aerobic prokayotes, but
were not digested; established “symbiotic relationship”
– Led to vast increase in multicellular organisms
Cladistics• Cladistics: The process used to
determine the sequence of branches in a phylogenetic tree
• Each branch of a phylogenetic tree is called a clade; it consists of an ancestral species and all of its descendants– Clades can nest within larger clades– A clade may represent an individual
species, genus, or family.– All members of a clade must share a
homologous feature that does not exist outside of the clade = derived characters (= synapomorphy)
Cladogram• Cladogram: A phylogenetic diagram that
specifies the derived characters of clades.
http://www.youtube.com/watch?v=46L_2RI1k3k
How to Draw a Cladogram
Spine Legs Hair Opposable Thumbs # of derived traitsWorm - - - - Fish + - - -
Toad + + - -
Lion + + + - Human + + + +
•Identify the “outgroup” that has no derived traits. •Use the number of derived traits (from lowest to highest) to help create your cladogram.
http://www.youtube.com/watch?v=ouZ9zEkxGWg
What derived traits make humans unique? Structural Differences
• Hairlessness• Skeletal structure
– Skull• Larger Brain Case• Less protruding mandible• Position of foramen
magnum
– Pelvis: Wider & shorter– Spine: Lumbar curve
What derived traits make humans unique? Cognitive Differences
• Ability to perform complex reasoning and exceptional ability to learn– Linked to longer
childhoods• Communicate using
complex language– Lower position of voice
box enables speech
Exam Review – Evolution Topics:•Species, Genetic Variation & Selection – natural selection & artificial selection •Mechanisms of Evolution – Hardy Weinberg equilibrium, genetic drift, gene flow •Microevolution vs macroevolution •Speciation – allopatric, sympatric •Patterns of evolution – convergent, divergent, co-evolution •Origin of Life – abiogenesis, endosymbiosis •Cladistics – create a cladogram p. 483-483•Human Evolution – characteristics of humans vs other primates/hominids Review Questions:•Evolution unit not in normal textbook – create your own notes and review homework questions•OR – sign out the other textbook