Unit 8 Organization of Life, Plants, and Evolution
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What is Evolution? Darwins Theory of Evolution (Chapter 15) A.
Charles Darwin In 1831 Charles Darwin took a trip to the Galapagos
Islands as a naturalist aboard the HMS Beagle. This trip took 5
years, and allowed him to see and collect collections of animal
species. What evidence led Darwin to develop the theory of natural
selection and common descent to explain evolution? Similiarities
between fossils, the relationships between finches and tortoises on
the different islands.
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B. Natural Selection Darwins Theory of Evolution is based on
the mechanism of Natural selection. Artificial Selection is what
happens when humans choose who breed and survive. Natural Selection
is what happens when only the most fit survive and nature
determines who will breed and survive. The Four principles of
Natural Selection include:
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1. Variation - Organisms in a population are different from one
another 2. Heritability - Traits are passed from parent to
offspring 3.Overproduction Populations produce more offspring than
can survive, this creates competition for resources. 4.Reproductive
Advantage Variations make some organisms of a species more likely
to reproduce and have more offspring than others.
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Evolution means to change over time. C. Evidence of Evolution
Darwins theory states that evolution is a result of natural
selection Evidence includes: 1. The Fossil Record allows scientists
to study and compare traits. a. Derived traits newly
evolved/different traits found in organisms b.Ancestral traits
traits similar between ancestor and modern day organisms.
c.Radioactive Isotopes- used to track the age of fossils
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Comparative Anatomy Related structures between organisms. a.
Homologous Structures - Similar structures inherited from a common
ancestor Example animal forelimbs b.Vestigial Structures Structures
that have reduced or lost function Examples snake pelvis, kiwi
wings, human appendix c. Analogous Structures Similar structures
inherited from unrelated species Species- not from common
ancestors. Examples eagle/beetle wings
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Divergent Evolution Ex:
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Convergent Evolution
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3. Comparative Embryology Similarities between vertebrate
embryos. 4. Comparative Biochemistry Similar enzymes, amino acids,
DNA, RNA, and other molecules 5.Geographic Distribution - Related
organisms share geographical distribution D. Adaptation An
adaptation is a trait that increases an organisms fitness Fitness
the measure of an organisms ability to make reproductively viable
offspring
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Adaptations include: 1. camouflage - to blend with
environments. camouflage 2.Mimicry - to resemble other species
3.Antimicrobial resistance to be immune to antibiotics
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**Remember, and Allele is one of the two traits given by an
offspring's parents. It is one letter in a genotype: Bb-B dominant
allele and b-resesive allele
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E. Mechanisms of Evolution In addition to natural selection
other mechanisms affect evolution. These include: 1. The
Hardy-Weinberg principle allele frequencies stay Constant, a
population is in genetic equilibrium. Example- Screech owls come in
two colors: Brown and Gray. Since the number of alleles that code
for brown and gray are the same, there is an equal proportion of
brown and gray screech owls in a population
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Hardy-Weinberg Principle
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2. Genetic Drift-change in allele populations due to chance
(Random reception of alleles from Mom and Dad Example- A group of
butterflies comes in two colors: blue and brown. The brown
butterflies die out, leaving only blue butterflies to pass on their
alleles to the next generation
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Sulfur Butterflies
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3. Founder Effect-a small population settles in an area and is
separated from the larger populationFounder Effect Example:
Galapagos Finches settled on different islands and developed
different characteristics
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4. Bottleneck-when populations decline to very small numbers
and then rebound, several traits may disappear in the population
Example- Northern Elephant Seals over a period of time many died
out and when the population made a comeback, there was less genetic
diversity
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5. Gene Flow-When individuals from other areas migrate into a
population, the genetic diversity of the population increases.
Example-A Species of Bird that is blue colored, has an individual
migrate in that is red colored.
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6.Nonrandom Mating: Selecting a mate for particular traits that
are found desirable. Links Closely with Sexual Selection: Example
Peacock, Antlers on a deer, and Male Frigate Bird
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7.Mutation-changes in a genetic code that occur randomly
Example-Antibiotic resistance in bacteria
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Types of selection: 1.Directional Selection- when there is
pressure for resources, the population moves towards a certain
trait to adapt: Ex: Giraffe Necks 2.Stabilizing Selection-
eliminates the extremes of a population: Ex: Rabbits with long legs
and short legs 3.Disruptive Selection- Eliminates the average
selection for organisms in favor of the extremes. Ex: Acorn
size
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4.Sexual Selection-selection of organisms with sexually
attractive traits: (Ex. Deer antlers) 5.Balanced selection
(polymorphism)- genetic equilibrium has occurred: No evolution
occurs.
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Reproductive Isolation Prevents groups of organisms from
Reproducing Speciation - Causes a population to diverge and split
into two separate species. 1. Allopatric - a physical
barrier-prevents species from mating Examples-Two species of
squirrel separated by the grand canyon
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2.Sympatric - no geographic barrier- individual species evolve
from common ancestors in the same location Examples-Species of
fruit flies have evolved to feed on different apples in the same
regions:
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Patterns of Evolution 1. Adaptive Radiation (also known as
divergence) One species gives rise to many Example different finch
species adapt to different habitats 2.Coevolution - a species has a
close relationship with other species Example orchids/moths,
sharks/remoras, etc. 3.Convergent Evolution - 2 unrelated species
become similar Example placental and marsupial animals
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Adaptive Radiation
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Co-Evolution
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Convergent Evolution
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F. Sexual Reproduction vs. Asexual Reproduction- Sexual
Reproduction gives an evolutionary advantage to organisms because
it gives them diversity. Example: immune systems develop in
response to new experiences with microbes and evolves with each
experience.
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Genetic Isolation is the prevention one species from mating
with another: 1. Llama and Camel
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2. Polar Bear and Brown Bear
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3. Cheetah and Leopard
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4. Fox Squirrel vs. Black Squirrel
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Archaeopteryx
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Terror Birds
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Cuttlefish camouflage
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Something to think about If it takes many years for species to
evolve than is it individuals or populations that evolve?
Populations: It takes an individual with certain adaptations and
many generations for the adaptation to evolve in the population. In
the end natural selection can be simply defined as: Bono is from an
island that consists of 200 people, from what you learned, what are
some assumptions that you can make about Bono and the rest of the
people on his island compared to that of someone from New York
City.
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Classification of Living Things The study of life is Biology
Draw the kingdom of science, and how each area of science is
related.
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Biology and the Animal Science The science of grouping
organisms on the basis of their similarities is called Taxonomy
Aristotle (350 BC) was the 1st to subdivide into two groups: Plants
and Animals Aristotles system lasted 2000 years
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Carleus Linnaeus developed a new system based on 7 groups: 1.
Kingdom 2. Phylum 3. Class 4. Order 5. Family 6. Genus 7.
Species
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Most animals are now referred to by their Genus and Species
This is called their Scientific Name and is a practice known as
Binomial nomenclature Examples: Homo sapiens, Humans : Canus lupus:
Domestic Dogs
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Organisms also have a Common name, which can sometimes cause a
great deal of confusion such as mountain lion: puma, cougar,
panther, catamount or starfish silverfish, jelly fish (none of
which are fish). Modern taxonomists now group according to
chromosome structure, reproductive potential, biochemical
similarities, embryology, and evolutionary relationships. Members
of the same species that differ in some important way are called
subspecies Linnaeus divided according to two kingdoms: Plant
Kingdom (autotrophs) Animal Kingdom (heterotrophs)
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Now we have 5 (actually 6) Kingdoms 1.Monera (simple organisms
without nuclei bacteria) 2 domains Archaebacteria and Eubacteria
2.Protista (with nuclei many are unicellular) 3.Fungi
(multicellular heterotrophs absorb food through cell wall mushrooms
etc.) 4.Plantae nucleated, multicellular autotrophs chloroplasts
5.Animalia multicellular heterotrophs nuclei
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The study of taxonomy is huge. Computers have helped a lot.
Identifying Organisms The study of classifying according to
evolution Systematics The study of evolutionary relationships and
phylogenies Phylogenetics The results of studies in systematics are
used to construct a Tree of Life
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Evolution by Natural Selection What are some differences you
have noticed in the size and shape of the dogs in your
neighborhood? Do their differences make them better at some things,
but not well-suited for others? What would happen if the world
suddenly changed, so the only thing that dogs could eat was deer
and there was absolutely no way for a dog to eat if it wasnt big or
strong enough to catch deer? Most likely, smaller dogs would die
off and the bigger ones would survive and reproduce. After a while,
instead of a population of dogs of all sizes, most of the dogs in
the population would be large dogs.
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Living things that are well adapted to their environment
survive and reproduce. Those that arent well adapted dont survive
and reproduce. An adaptation is any characteristic that increases
fitness, which is defined as the ability to survive and reproduce.
What are some characteristics of animals or plants that affect
their fitness?
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If a mouses fur color is generally similar to its mothers color
what color fur would be most common among the pups?
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A more complete definition of fitness is the ability to survive
and produce offspring who survive and reproduce. Below are
descriptions of four male lions. According to this definition,
fitness, which lion would biologists consider the fittest? Explain
why.
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Suppose that Tyrone had genes that he passed on to his cubs
that helped his cubs to resist infection, so they were more likely
to survive to adulthood. These genes would be more common in the
next generation, since more of the cubs with these genes would
survive to reproduce. A characteristic which is influenced by genes
and passed from parents to offspring is said to be inherited. Over
many generations, heritable adaptive characteristics become more
common in a population. This process is called evolution by natural
selection. Evolution by natural selection takes place over many,
many generations.
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Evolution by natural selection leads to adaptation within a
population. The term evolution by selection does not refer to
individuals changing, only to changes in the frequency of adaptive
characteristics in the population as a whole. For example, none of
the mice had a change in the color of their fur, but tan fur was
more common for the pups than for the mother mice. In summary, a
heritable characteristic that helps an animal or plant to have more
offspring survive to reproduce will tend to become more common in a
population as a result of evolution by natural selection.
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Questions: 1.Explain why a characteristic which helps an animal
to live longer will generally tend to be more common in the
population as a result of evolution by natural selection. 2.Not all
characteristics which contribute to longer life become more common
in the population. Some characteristics contribute to long life,
but no more offspring. For example, a female which is sterile and
cannot have any offspring may live longer because she will not
experience biological stresses of repeated pregnancies. Explain why
a characteristic like this which contributes to a long life, but
with few or no offspring, would not become more common as a result
of evolution by natural selection.
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#1 #2 Key out the following organisms:
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#3 #4
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#5 #6
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#7 #8
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#9
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#10 #11
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#12 #13
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#14 #15
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#16 #17
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#18 #19
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#20 #21
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Vascular Plants Three parts of a vascular plant 1.Waxy outer
cuticle that retains water 2.Stomata that allow gas exchange 3.A
Vascular System (Xylem and Phloem)
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The Vascular System 1.Xylem (carries water) 2.Phloem (organic
materials food) This allows these plants to live successfully on
land farther away from direct sources of water. All produce
seeds
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Seed Plants: Gymnosperms (naked seeds) These plants have
needle-like leaves Cones are used to protect the seeds Most of
these plants do not lose leaves Examples include spruce, fir,
redwoods
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Angiosperms Angiosperms are the most successful of all plants
They have ovules that are totally enclosed They have colorful
flowers that contain both male and female reproductive parts
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Monocots: plants with 1 cotyledon: 1 Baby leaf Dicots: Plants
with 2 cotyledons: 2 Baby leaves
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Monocots vs Dicots
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Flowers and Fruit All angiosperms produces reproductive
structures called Flowers: Flowers contain both male and female
parts. Once Egg and Sperm are fertilized, the flower falls off and
the structures develop into fruits. This protects and disperses
seeds.
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Kinds of plant Tissue Epidermis outermost protective covering
of the plant. Secretes a waxy layer of cutin. Vascular Tissue
Plumbing system of xylem (water transport) and phloem (food
transport) Ground Tissue unspecialized tissue that serves as
protection and storage of food for the plants
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Roots Anchor the plant, absorb minerals from the soil and store
food produced in leaves.
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Stems: Woody Stems: transport food water and minerals between
roots and leaves and support the plant Buds a protective covering
of the sensitive growing leaves so plant tips wont dry out
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Leaves Blade: broad part of leaf, contains photosynthetic cells
Petiole: leaf stalk, supports the blade Simple leaf: single
un-divided blade Compound Leaf: divided into several parts
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Structure of the Leaf Epidermis: single layer of cells for
photosynthesis with waxy layer of cutin. Cutin: wax that helps slow
evaporation Stomata with Guard cells: opening allows gas exchange
with special cells that open and close stomata Mesophyll middle
portion of the leaf Leaves and Water Loss Transpiration process of
losing water
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Stomata and Guard Cells (371) GAS EXCHANGEGAS EXCHANGE
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L e af St r u ct u re Gas Exchange occurs here (CO 2 in O 2
out) (364)
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Reproduction
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Pollination The process in which flowers sexually reproduce
Fertilization The union of an egg and a sperm of a plant Fruits and
Seeds when the ovary of the plant swells and ripens to protect the
seed, it is a fruit
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Asexual Reproduction has the same genes as the parent plant
Natural Propagation producing new individuals from roots or stems
1.Runners: also called stolons, low growing stems above the soil to
make a new plant: strawberries 2.Rhizomes: long growing stems that
grow below the surface to make a new plant: Potatoes and Yams
3.Bulbs: short stems surrounded by layers, self reproducing: Onions
Artificial Propagation when humans reproduce vegetables
artificially 1.Cuttings: cut a piece of stem and put it in water,
and then, replant it. Lilac bushes 2.Grafting: cutting the stem of
one plant and attaching to another: Grapes
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How can you tell the age of a fossil? Radioactive isotopes-
Some Elements decay over time. Carbon-14 Decays at a rate of losing
part of its nucleus every 5,730 years. When checking the rate of
decay, Scientists can figure out how old fossils are. Scientists
not only take samples from the bones, but from the rock that was
found around the bones.
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Speciation evolutionary process that creates new species.
Divergent Evolution- when related organisms become less alike: Ex:
Brown Bears vs Polar Bears Adaptive radiation- members of a species
adapt to a variety of different habitats. Example: different finch
species Convergent Evolution- Distantly related organisms develop
similar features. Ex. Sharks and Whales Mimicry- Evolution of one
organisms to look like another
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What are some factors that decrease the chance of a population
to evolve? 1. Lack of pressure from predators 2. Enough food to
feed the population 3. No individuals migrating into the population
(In other words: No changes at all)