|
|
Supports
to Natural Selection: Anthropogenic Selection
Artificial
Breeding
Industrial
Melanism
Insecticide/Pesticide
Resistance
Resistance
to antibiotics
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Adaptive
Radiation: process of evolution of different species from a geographical
area, by moving into different geographical area (habitat).
E.g
Australian Marsupial
More than
one adaptive radiation in an area – Convergent evolution
e.g. Australian
Marsupial & Placental mammals
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Vestigial
organs: Organs present in non-functional forms.
e.g.
Vermiform appendix, Nictitating Membrane, hair on body
|
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Connecting
Links: organisms possessing characters of two different groups of organisms,
e.g.
|
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Missing
Links: Fossil evidence showing combined forms of two groups. E.g Archaeopteryx
(reptiles & Birds)
|
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Atavism:
reappearance of ancestral characters. E.g. short tail in human babies, winged
petiole in citrus
|
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|
|
Lamarck’s
Theory: Use & Disuse of organs
Characters
are acquired due to new needs in changing environment.
|
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|
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Mutation
Theory: Hugo de Vries (Evening Primrose)
New species
originate due to mutations or discontinuous variations
Mutations
subjected to natural selection
If unfavourable;
destroyed
|
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Synthetic
Theory: synthesis of Darwin’s & Hugo de Vries theories
Five basic
factors of evolution:
1.
Mutations
2.
Gene Recombinations
3.
Gene Migration / Gene Flow
4.
 Genetic
Drift Founder Effect
5.
Hybridisation
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|
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Types of
Natural Selection:
1.
Stabilising Selection: favours average
characteristics & eliminates extremes
2.
Directional/Progressive Selection: favors
non-average or extreme for of trait & pushes population in one direction
3.
Disruptive Selection: favours both extremes
and eliminates individuals with average traits. Forms two peaks in
population. Two different populations formed.
Disruptive
section leading to formation of two new species – adaptive radiation
|
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|
|
Hardy
Weinberg Principle:
Describes theoretical
situation where no evolution is occurring in a population
i.e.
frequency of alleles in a population is constant – genetic equilibrium
uses
algebraic equation:
For a gene
A with 2 alleles A & a
Genotypes Frequency
AA p
aa q
Aa 2pq
Where, p frequency of dominant allele in population
q frequency of
recessive allele in population
p2
Probability of occurrence of homozygous dominant
q2 Probability
of occurrence of homozygous recessive
2pq Probability of
occurrence of hetrozygous
Allele frequency: p+q=1
So genotype Frequency: p2+q2=2pq=1
|
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|
|
Conditions/Absence
of Genetic Equilibrium: Absence of
Mutation,
Gene Flow, Genetic Drift, genetic recombination, natural selection
Founder
Effect: Drifted population forming a new species (founder species) in the
new area.
|
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|
Lobefins (Coelacanth):
fish capable of traversing between land & water
Difference
in eggs of amphibians & reptiles?
|
Evolution
chronology:
3 eras:
Paleozoic, Mesozoic & Cenozoic
Age of
Ferns & Amphibians: carboniferous
Origin of
Angiosperms & Age of Dinosaurs: Jurassic
Current
Age: Quaternary
|
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|
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Evolution
of Man:
Dryopithecus:
15mya, knuckle walker
Ramapithecus:
14-15 mya, walked like gorilla
Australopithecus:
5mys, erect walker, omnivorous Cranial capacity 500cc
Homo
habilis: 2 mya, fully erect, vegetarian (no meat), tool maker Cranial capacity
650 – 800 cc
Homo
erectus: 1.5mya, meat eaters, used fire, Cranial capacity 900cc
Neanderthals:
40,000 to 100,000 yrs ago, Omnivorous, Cranial capacity 1400cc
Homo
sapiens: 25,000 yrs ago, Omnivorous, Cranial capacity 1300-1600cc
|
Showing posts with label Evolution. Show all posts
Showing posts with label Evolution. Show all posts
Saturday, 9 February 2019
Key Points: Evolution Part 3
Key Points: Evolution (Big Bang & Origin) Part 1
XII |
EVOLUTION
|
QUESTIONS |
NOTES |
|
|
Age of
universe: 20 bn yrs ago
Age of
Earth: 4.5 bn yrs ago
Life
appeared: 4 bn yrs ago
|
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|
Universe m/o clusters of galaxy. Galaxy m/o clusters of stars,
clouds of gases & dust.
BIG BANG THEORY: explains origin of
universe.
|
|
|
Composition
of Earth: Water vapour, methane, CO2, NH3 (frm molten
mass on Earth’s surface)
No atmosphere
|
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|
Processes on Earth post big bang led to formation
of CO2, water etc.
|
|
|
Theories
of Origin of Life:
·
Panspermia: Life came from outer space as ‘spores’
·
Spontaneous generation: Life originated from
decaying matter
·
Life comes from pre-existing life – Louis Pasteur
·
Abiological Origin of life: Oparin &
Haldane
·
Exp demo of above: Miller
|
|
Define Biogenesis
|
Biogenesis/
Chemical Evolution:
Inorganic
molecules  Non-living organic molecules s/a proteins,
RNA etc. Life
Conditions required: High temp, Volcanic
storms, reducing atmosphere containing CH4, NH3 etc
|
|
|
Miller’s
exp:
Flask with:
CH4, NH3, H2 (red. Atm)
Water vapour
Electric
Spark (high temp – 800°C)
Result: Amino acids formed
Further Proof:
·
Others obtained sugars, pigments, fats, N
bases in similar exp
·
Meteorite content reveals similar material
from other places in space
|
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