Evolution, Natural Selection and the Diversity of Animals.
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Transcript of Evolution, Natural Selection and the Diversity of Animals.
![Page 1: Evolution, Natural Selection and the Diversity of Animals.](https://reader036.fdocument.pub/reader036/viewer/2022062516/56649e495503460f94b3c01e/html5/thumbnails/1.jpg)
Evolution, Natural Selection and the Diversity of Animals
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How do new species begin?
• DNA is instructions for all life
• DNA - RNA Protein Trait
• Mutations MAY cause changes in the production of proteins
• New traits can be passed to offspring– May be helpful, bad or cause no change at all
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Mutations• Changes in the DNA sequence of nucleotides:
A’s, G, C’s and T’s– Sickle cell anemia – Harmful? Helpful?– Albinism– Cystic fibrosis– Most diseases and deformities– Blond or brunette– 2 legs or 4 legs?– Fins or flippers?– Color of skin– All differences!
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Mutations: the good, the bad, and the indifferent
• Point mutations – one letter change; substitution
• Frame-shift mutations – insertion or deletion of one or more nucleotides that “shifts” information;
• each 3 code for 1 amino acid that makes up a protein• EX: cat ate the ratcatatetherat
• caatatetherat Caa tat eth era t
• Ctatetherat Cta tet her at
• Not all mutations are bad – some make bacteria ANTI-BIOTIC RESISTANT.
Good for the bacteria, not-so-good for you!
• Some mutations result in no change
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Mutations can change a population • If new traits is advantageous,
• those w/ trrait will have more successful offspring than those without it
• Over long periods of time…
• populations -- new species• Fish w/ lungs move onto land reptile humans!
• Species = groups that are so similar they can breed with each one another and produce VIABLE (capable of reproducing) offspring.
This is Natural Selection.
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New species can develop if…
• Members of a populations are separated from each other (GEOGRAPHIC ISOLATION)
• Members of two populations can no long breed successfully with one another (REPRODUCTIVE ISOLATION)
• Having an abnormal number of chromosomes (POLYPLOIDY)
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Divergent Evolution
• One ancestral species leads to 2 new species
Ancestral Green Iguana
Marine Iguana
Land Iguana
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Adaptive Radiation
• One ancestral species leads to 3 or more new species
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Types of Evolution
Two ideas of how new species develop
• Gradualism: lots of small changes in DNA over long periods of time
• Punctuated Equilibrium: fewer, larger changes over long periods of time.
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Gradualism
Punctuated Equilibrium
10 million years
10 million years
Notice the results of both are the same: CHANGE
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Evidence for evolution
• Antibiotic resistant bacteria
• Fossils
• Anatomy
• Embryology
• Biochemistry
All of these methods are used together to show relationships between species
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Fossil RecordUsed to observe early life:
• Incomplete – only hard parts fossilize in specific types of soil
• Like a puzzle – overall pattern
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Anatomy• Similarity in structures
suggests relationships between animal species
• Homolgous and Analogous structures – see diagram
• Vestigial structures – whale pelvis
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Homologous and Analogous Structures
• Homologous structures (homo=same) – alike because they are closely relatedExample: bird wings, bat wings, your arm and hand
• Analogous structures (not closely related, but same function)
- -bird wings and
insect wings
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Embryology• sperm + egg fertilization zygote (1
cell)
• blastula – about 64 cells
• gastrulation – when blastula begins to fold in– Forms opening into gastrula– gastrula – 2 cells layers = 2 tissue layers
• archenteron – opening into the gastrula
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Protostome vs Deuterostome
If the archenteron (opening) forms into:• a mouth first = PROTOSTOME• an anus first = DEUTEROSTOME• All invertebrates (no backbone) are
protostomes except echinoderms• Vertebrates (w/backbone) and echinoderms
= Deuterostomes• Humans?
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Living things are grouped according to similarities
• Embryology
The more similar the
embryonic
development pattern the
more closely related
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Embryology
Vertebrate embryos share developmental characteristics:– Post anal tails– Pharyngeal slits or pouches– Notochords– Nerve cords
DNA determines these characteristics!
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Biochemistry
• All organisms have DNA, ATP, and other enzymes/proteins in common
• DNA is made of 4 molecules: A,T,C, and G
• Similar DNA sequences = similar ancestry
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A cladogram is like a family tree showing how things have changed.
Shows relationships based on specific characteristics
Everything to the right of this point have Vertebrae
Point where common ancestors diverged
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Living things are grouped according to similarities
• Kingdom• Phylum• Class• Order• Family• Genus • Species
Few similarities Largest # of organisms
Most similarities Smallest # of organisms
Binomial Nomenclature: scientific names are Genus and Species Ex: Iguana iguana, Homo sapien
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HOMOLOGOUS structures, humans, birds, porpoises and elephants are considered more closely related to each other than any are to insects.
Living things are grouped according to similarities
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Dichotomous keys
• Species can be identified using a dichotomous key
• Series of “either / or” questions leading to the identification.
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Dichotomous keys
Example:
1. Does the flower have white or yellow petals?
-if yellow, it is a sunflower
-if white, go to question 2
2. Does the flower have a yellow or red center?
-if yellow, it is a daisy
-if red, go to question 3