General Zoology Unit One

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General Zoology Unit One
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Science
The observation of natural phenomena and the
methods used to determine how those phenomena
occur
Science is constrained by natural laws, therefore
science must be conducted within the realm of
these natural laws
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The Scientific Method
Steps
1. Observation (a question)
2. Hypothesis
3. Experimentation
4. Conclusion Reporting
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The Four Commonalities of All Organisms
Common genetic molecule
Common evolutionary forces
Natural Selection
DNA
Common unit of life
Common environment
The cell
Earth
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Chemical Evolution
The ancient atmosphere was a reducing one,
therefore hydrogen levels were great and oxygen
levels were miniscule
The ancient atmosphere contained mainly methane
and ammonia
Free energy to produce chemical reactions came
from UV light, lightning and volcanoes
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Chemical Evolution
Organic molecules are not stable in the presence
of molecular oxygen, so this atmosphere was
conducive to their formation
With exposure to the free energy, the methane and
ammonia mixture could then form sugars and amino
acids
In this hot soup mixture of the early oceans
the four organic types could have assembled
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Chemical Evolution
With the assemblage of the organics, some of them
would have had to become self replicating (RNA
DNA)
With the ability to self replicate, these
chemical systems could organize into living,
self reproducing cells
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Chemical Evolution
When these protocells began to respond to natural
selection, evolution of the genetic code and
protein synthesis followed and would meet the
requirements for being the common ancestor of
living things
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Domains
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Eukarya
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Archaea
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Eubacteria
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The Six Kingdom Classification System
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Eubacteria
Prokaryotic
Unicellular (single celled)
All have cell walls
Autotrophic (producer) or heterotrophic
(consumer)
Asexual reproduction (binary fission) and
conjugation (gene mixing)
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Archaebacteria
Prokaryotic
Unicellular (single celled)
All have cell walls
Heterotrophs and chemotrophs
Have some eukaryotic like genes and live in
extreme conditions
Asexual reproduction (binary fission) and
conjugation (gene mixing)
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Protista
Eukaryotic
Unicellular (single celled)
Many have cell walls
Autotrophic (producer) or heterotrophic
(consumer)
Asexual reproduction (binary fission) and
conjugation (gene mixing)
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Fungi
Eukaryotic
Multicellular (most)
All have cell walls
Heterotrophic (consumer)
Sessile
Asexual sexual reproduction
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Plantae
Eukaryotic
Multicellular
All have cell walls
Autotrophic (producer)
Sessile
Asexual sexual reproduction
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Animalia
Eukaryotic
Multicellular
None have cell walls
Heterotrophic (consumer)
Capable of movement
Asexual sexual reproduction
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Definitions
Systematics the study of the biological
diversity of organisms and their evolutionary
relationships
Taxonomy the study of the identification and
classification of species
Classification the system used to name and
order species and their related groups
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Definitions
Phylogeny the evolutionary history of a species
or group of related species
Homology similar characters found in related
groups due to a common ancestor
Homoplasy similar characters found in unrelated
groups with no common ancestor
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Homologous structures
Can
Divergent evolution
lead to
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Analogous structures
Convergent evolution
indicate
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Mutual adaptations
lead to
Parallel evolution
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Definitions
Clade a group consisting of an ancestral
species and all of its descendants
Plesiomorphic ancestral characters found in all
members of a clade
Symplesiomorphy the sharing of ancestral
characters in a clade
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Definitions
Derived character a character that arises after
the common ancestor
Synapomorphy the sharing of derived characters
among a clade
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Symplesiomorphy
Synapomorphy
Derived character
Plesiomorphic character
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Sources of Information for Reconstructing
Phylogeny
Comparative morphology
Comparative biochemistry
Comparative cytology
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Sources of Information for Reconstructing
Phylogeny
Comparative morphology
- examines the physical features of extinct and
extant organisms
- uses homologous and vestigial structures to
determine phylogeny
- vestigial structures are those that are
retained, but not longer used
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Sources of Information for Reconstructing
Phylogeny
Comparative biochemistry
- examines the sequences of amino acids and
nucleotides
- quantifies the similarities among extant
organisms
- usually cannot be used on extinct organisms
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Sources of Information for Reconstructing
Phylogeny
Comparative cytology
- examines the numbers and sizes of chromosomes
in extant organisms
- compares how cells and tissues develop
- usually cannot be used on extinct organisms
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A typical phylogenetic tree
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Definitions
Monophyletic group a group that contains all
the descendants of the most common ancestor
Paraphyletic group a group that contains the
common ancestor and some, but not all of its
descendants
Polyphyletic group a group that does not have a
recent common ancestor
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Taxon 1 - monophyletic
Taxon 2 - polyphyletic
Taxon 3 - paraphyletic
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Phenetics
Also known as numerical taxonomy
Quantitatively analyzes the number of phenotypic
characters
It makes no attempt to determine common ancestry,
therefore no grouping
Used today mainly by comparative biochemists
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Phylogenetic Taxonomy
Also known as cladistics
Uses derived characteristics to reconstruct
phylogenies
This approach emphasizes common ancestry
Groupings must be monophyletic
Results shown in a cladogram
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Evolutionary Taxonomy
Uses shared ancestral and derived characteristics
to reconstruct phylogenies
This approach emphasizes common ancestry, as well
as the extent of divergence
Groupings are monophyletic with some paraphyletic
Results shown in a phylogenetic tree
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Species Definitions
Biological a group of populations in which
genes are exchanged through reproductively
isolated breeding, producing viable offspring
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Species Definitions
Evolutionary a single lineage of populations
that maintains its identity from other lineages
and that has its own evolutionary tendencies and
historical fate
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Species Definitions
Phylogenetic a group of organisms that are
diagnosably distinct from other groups and in
which there is a parental pattern of ancestry and
descent
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Carolus Linnaeus
The Father of Modern Taxonomy
Hierarchical system of taxa
Latinized names
Binomial nomenclature
The scientific name
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Domain
Eukarya
Kingdom
Animalia
Phylum
Chordata
Class
Mammalia
Order
Carnivora
Family
Felidae
Genus
Panthera
leo
Species
Panthera leo
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Charles Darwin
Theory of Natural Selection descent with
modification
Influenced by his voyage on the Beagle, James
Hutton, Charles Lyell, Thomas Malthus and others
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HMS Beagle Voyage
Darwin noticed gradual changes in the same
species as he moved from north to south and up in
elevation, leading to the hypotheses of
gradualism and adaptive traits
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James Hutton
Hutton, a geologist, proposed the theory of
gradualism
Darwin took the ideas of Hutton and thought if
the earth can gradually change over long periods
of time, why not organisms?
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Charles Lyell
Lyell, a geologist, stated the concept of
uniformitarianism
Darwin took the ideas of Lyell and thought if the
earth can gradually change over long periods of
time, why not organisms?
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Thomas Malthus
Malthus was an economist that stated if a
population outgrew its resources, it would
restrain the population
Darwin applied this to organisms
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Erasmus Darwin
Darwin was Darwins grandfather who formulated
one of the first theories of evolution
Darwin wrote of life evolving from common
ancestors, but did not present a mechanism
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Jean-Baptiste Lamarck
Lamarck published his theory of evolution the
year Darwin was born
Larmarcks mechanism of evolution was acquired
characteristics
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Alfred Wallace
Wallace was a contemporary of Darwins and
developed the same theory of natural selection
Wallaces letters to Darwin prompted Darwin to
write and publish the theory first
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Darwins Four Postulates of Natural Selection
1. Each generation will produce more offspring
than can possibly survive
2. Inherited variations occur due to random
mutations. These can be harmful, helpful or
neutral
3. Because of limited resources, not all
offspring survive. Those with the most
advantageous variations will survive.
4. The adaptive traits are perpetuated in the
following generations non-adaptive are
eliminated
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Darwin - gradualism
Vs.
Eldredge Gould punctuated equilibrium
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Darwin - gradualism
Vs.
Eldredge Gould punctuated equilibrium
A combination of both is probably the most correct
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Sources of Evidences for Natural Selection
Comparative morphology
Comparative biochemistry
Comparative cytology
Biogeography
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Sources of Evidences for Natural Selection
Comparative morphology, comparative biochemistry
and comparative cytology were discussed earlier
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Sources of Evidences for Natural Selection
Biogeography
- examines the geographic distribution of
organisms
- implies that we find modern species where they
are because their ancestors lived there
- analyzed in the context of extinct and extant
organisms
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Mechanisms of Selection
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Stabilizing Selection
Intermediate forms of a trait are favored
Extreme forms of a trait are eliminated
Tends to counteract the effects of mutations,
gene flow genetic drift to preserve the most
common phenotype
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Directional Selection
Forms of a trait shift toward one extreme due to
environmental changes
Adaptive mutations can also cause this shift
Tends to reduce or eliminate the original most
common phenotype
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Disruptive Selection
Extreme forms of a trait are favored
Intermediate forms of a trait are eliminated
Tends to shift to the extreme forms due to
extremes in the environment
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Microevolution Macroevolution
Microevolution is the modification of a
population (gene pool) by small changes in allele
frequencies
These changes are brought about by mutation,
natural selection, gene flow and genetic drift
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Microevolution Macroevolution
Macroevolution is the appearance and extinction
of a species
Macroevolution is many times the result of
accumulating microevolutionary changes
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Microevolution Macroevolution
Macroevolution tends to span enormous time
frames, whereas microevolution happens rapidly
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Hardy-Weinberg Equilibrium
An unlikely situation which mathematically
describes what happens if evolution does not occur
Produces a baseline for comparison
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Hardy-Weinberg Equilibrium
Hardy-Weinberg conditions large population
mating is random no migration,
mutation or natural selection
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Hardy-Weinberg Equilibrium
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Hardy-Weinberg Equilibrium
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Natural Selection
A gene pool is all the genes found in an entire
population
In theory, this is a pool of genetic resources
shared by all members and passed on to the next
generation
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Natural Selection
Remember, each gene is present in two or more
forms called alleles
These different forms can create a tremendous
amount of variation
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Natural Selection
Allele frequency is the abundance of each kind of
allele in a population
Due to the size of a gene pool, the frequency
does not change rapidly, usually taking many
generations
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Natural Selection
Genetic equilibrium is a theoretical reference
point in which the allele frequency of a given
gene remains stable from one generation to the
next
If this stability continues, the population is
not evolving in respect to that gene
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Natural Selection
Crossing over, independent assortment,
fertilization, change in chromosome number or
structure will lead to new combinations of genes
BUT NOT NEW GENES!
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Natural Selection
Changes in gene frequencies occur through
mutations and gene flow
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Natural Selection
Mutations are changes in DNA sequence that can
produce new alleles
Mutations can be lethal, neutral or beneficial
Beneficial mutations are very rare, but can
increase fitness
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Natural Selection
Population members with the best adaptations
(beneficial genes) are the ones that survive to
reproduce
Over many generations the survivor genes can
alter the allele frequencies
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Natural Selection
Gene flow is the movement of genes into and out
of a population (gene pool)
Immigration new genes entering the pool
Emigration current genes leaving the pool
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Natural Selection
Genetic drift is the random change in allele
frequency brought about by chance alone
The larger the population, the less chance of
drift
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Natural Selection
Genetic drift can be caused by
inbreeding
bottleneck effect
founders effect
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Natural Selection
Inbreeding the constant mixing of genes among
closely related individuals
Inbreeding produces the effect of concentrating
alleles found only in the closely related group
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Natural Selection
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Natural Selection
Founders effect occurs when a small group breaks
away from the original population
The genes carried by these individuals may cause
a change in the allele frequency found in the
original population
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Natural Selection
Founders effect
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Natural Selection
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Biological Species Definition
A group of populations in which genes are
exchanged through reproductively isolated mating,
producing viable offspring
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Reproductive Barriers
Prezygotic reproductive isolation - six forms
Postzygotic reproductive isolation - two forms
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Reproductive Barriers
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Speciation Patterns
Allopatric Speciation
Sympatric Speciation
Parapatric Speciation
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Allopatric Speciation
This type of speciation occurs due to the
development of a physical barrier
The physical barrier splits the population,
preventing gene flow
Due to possible differences in the genetic
variations of the new groups, speciation may occur
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Sympatric Speciation
This type of speciation occurs within the home
range of the population
A very slight ecological separation may influence
sexual selection, leading to speciation
This speciation can also occur in plants through
polyploidy
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Parapatric Speciation
This type of speciation occurs when two
neighboring populations become distinct species
Interbreeding may occur in a hybrid zone between
the two populations
These adjacent populations may evolve into two
distinct species while maintaining contact along
a border
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Ecology
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Ecology
Organism a living thing
Population a group of like organisms living in
a given geographic location
Community a group of populations living in a
given geographic location
Ecosystem all the biotic and abiotic factors in
a given geographic location
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Ecology
Biome a large geographic area in which abiotic
conditions are similar, therefore inhabited with
similar species
Biosphere anywhere on earth in which life
exists
Ecology the study of the relationships between
organisms and their biotic and abiotic
environments
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Ecosystems
Habitat the physical area in which an organism
lives
Niche the total of all resources a species
exploits for it survival, growth reproduction,
and the effects of that exploitation
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Ecosystems
Food Chain a linear biological sequence of the
movement of energy through organisms
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Ecosystems
Food Web a collection of integrated food chains
found in an ecosystem
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Ecosystems
Ecological succession is the gradual and
directional process in which a community changes
by the replacement of species
Ecological succession occurs in two forms
primary and secondary
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Ecosystems
Ecological succession
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Ecosystem Energy Flow
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Ecosystem Energy Flow
The Ten Percent Rule
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Ecosystem Energy Flow
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Symbiosis literally means living together. It
is an umbrella term that describes a variety of
relationships that exist between members of
different species.
Symbiotic relationships are commonly found among
all organisms.
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Mutualism both members gain a benefit ( )
Commensalism one member gains a benefit while
the other is unaffected ( 0)
Parasitism one member gains a benefit while the
other is harmed ( -)
Competition neither member benefits due to
reduced fitness (- -)
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Predation one species consuming another ( -)
All of these relationships influence population
size, fitness and adaptation
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Population Growth and Limits
r-selected species
K-selected species
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Population Growth and Limits
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Population Growth and Limits
Density dependent factors crowding,
competition, predation, disease
Density independent factors natural disasters,
weather changes, human environmental disasters