Download Chp 21 evidence for evolution notes

Evidence for Evolution Chp 21 notes
Darwin and finches - Correlation of species to food source. Finches
on different islands developed type beaks due to natural selection
according to type of food available.
Beak variation in Galapagos finches
(a) Cactus eater. The long, sharp beak of the cactus ground finch
(Geospiza scandens) helps it tear and eat cactus flowers and pulp.
(b) Insect eater. The green warbler finch (Certhidea olivacea) uses
its narrow, pointed beak to grasp insects
(c)Seed eater. The large ground finch (Geospiza magnirostris) has
a large beak adapted for cracking seeds that fall from plants to the
ground.
• Throughout many generations the beak shape changes
depending on the available food sources.
• The changes are reflected in the genetic differences of the finches.
• The finches adapt to the food source that is available
Natural selection requires three conditions to be met
 Variation must exist in the population
 These variations lead to differences in reproductive success of individuals
 These variations are transmitted to the next generation
The Peppered Moth
• Studied for the last two hundred years.
• Majority had light colors, camouflage while on trees and lichen.
• Pollution in England caused lichens to die during the Industrial Revolution.
• Trees became black with soot causing moths to die off due to predators.
• This helped the darker moths flourish because they were ability to hide on
dark trees.
Examples of Natural Selection
 Evolution of drug resistance in HIV
 Antibiotic Resistant bacteria
Artificial Selection –
• The breeding of domestic plants and animals
• The intentional breeding for certain traits
• Corn selected
Evidence for evolution –
1) Fossil Evidence
2) Anatomical Evidence
3) Vestigial structures
4) Embryological Homology
5) Molecular Homologies
1)
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Fossil Evidence –
Fossilization is an event that preserves evidence of past living organisms
Fossilization is relatively rare in softer tissue
There are fossils found that appear to be possible ancestors of modern organisms
Some transition fossils (intermediates) have been found, but never as many as Darwin
predicted
Archaeopteryx
Winged reptile. Possible link between reptiles and birds.
Probably a type of velociraptor
Horse evolution  Has more fossil evidence than any other but still has several gaps.
2) Anatomical evidence –
a. Homologous structures - _____________ Structural resemblance that possibly indicate
related ancestry of species. Ex. Bat wing, cat leg
b. Analogous structures – ______________- Structures that are similar in function but
different in development and don’t indicate relationship Ex. Bird wing and insect wing
c. Vestigial organs – organs still present and not used anymore. Ancestral evidence
Homologies – Homologous
Analogies- Analogous
Embryological homologies
 Haeckel (1874) Said all vertebrate classes pass through an identical evolutionarily
progression though out development. This is NOT the case
However  There are some similarities between all vertebrate embryos at early development.
Pharyngeal pouches (similar to gill slits) and tails
5. Molecular Homologies
• Similar DNA and Proteins
• The primary evidence to determine relatedness
Patterns of Evolution
C) Co-evolution – when 2 organisms evolve together
• Ex. star orchid and hawk moth
Each Have specific structures adapted to each other for pollination
 Host – parasite
 Hook worm – lives in humans
 Can provide humans with disease prevention and lower bad immune
response
B) Convergent evolution – Organisms that appear similar but are not
closely related
– Ex. Shark and porpoise = fish and mammal with similar
structures.
A) Divergent evolution – When related species become more and more
different.
– Ex. German shepherd and poodle = both dogs
 Elephant and mammoth - Called divergent parallel evolution
 Thought to have a common ancestor long ago, and then evolved similarly
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Biogeography - Geographic isolation leads to differences
 The flying lizards (genus Draco) of Southeast Asia. Differ in size according to location