LIFE SCIENCES PII
EVOLUTION
Origin of Ideas About Origins
Evidence of Evolution
Fossil Records
– Fossils are the remains, imprints, or footprints of an organism, usually preserved in rock
– Fossils indicate organisms, climate, and environments of the past
– The fossil record is the accumulation of all listed and known fossils
– Specific conditions are necessary for fossilisation: rapid burial, high pressure, low oxygen,
hard bodies.
– Fossils become older the deeper that they are buried. The timeline of organisms is
indicated by the fossil record. Simpler organisms with less biodiversity are found in deeper
rock strata, while greater biodiversity and complex organisms are found in shallower rock
strata
– Transition forms which show the transition state from one type of organism to another are
rare
Modification by Descent
– The basic body plans of different plants and animals are similar with various adaptations
for different habitats
In Vertebrates
– Pentadactyl limbs in various vertebrates have different functions but similar structures
– Functions include digging, flying, running, swimming, and climbing
– Shared characteristics
– One proximal bone (humerus)
– Two distal bones (radius/ulna)
– Number of wristbones (carpals)
– Five metacarpals in the palm
– Five phalanges
– Homologous structures - same body plan, different functions - may have come from (a)
shared ancestor/s.
– Divergent evolution: common ancestor develops differently in different environments.
– Analogous structures: same function, different structure
– Convergent evolution: unrelated organisms develop structures with similar functions
Modification within a Species
– Species change within themselves to get to modern day species
– E.g. the evolution of the horse
, Biogeography
– The geographical distribution of extant and extinct species show that closely related
species occur in the same geographical regions.
– New species may form as a result of geographical barriers:
– Large mountain ranges
– Large masses of water
– Small landmasses
– Deserts
– Some regions with similar conditions in different places on the globe contain different
species which are very similar to each other
Genetics
– Closely related organisms have more similarities in their DNA
– Explains the source of variation necessary for evolution
– Shows how characteristics are passed from generation to generation
Comparative Biochemistry
– Most living organisms have similar molecular compositions
– DNA structure
– Coding for protein synthesis/nitrogenous bases
– Process of protein synthesis
– Common set of amino acids
– Metabolic processes/enzymes
– ATP as an energy carrier
– Hox/master control genes determining bodily development
– Phospholipid membranes
Vestigial Structures/Organs
– Structures/organs that have reduced/decreased in size with disuse in some organisms
while others still use them fully indicate common ancestors
Comparative Embryology
– Hypothesis proposing that embryonic development of various vertebrates was very similar
– Proven to be inaccurate, and no longer used to in support of evolution
Development of the Theory of Evolution
Erasmus Darwin
– Ideas influenced his grandson, Charles Darwin
– Proposed that:
– All life on Earth shared a single common ancestor
EVOLUTION
Origin of Ideas About Origins
Evidence of Evolution
Fossil Records
– Fossils are the remains, imprints, or footprints of an organism, usually preserved in rock
– Fossils indicate organisms, climate, and environments of the past
– The fossil record is the accumulation of all listed and known fossils
– Specific conditions are necessary for fossilisation: rapid burial, high pressure, low oxygen,
hard bodies.
– Fossils become older the deeper that they are buried. The timeline of organisms is
indicated by the fossil record. Simpler organisms with less biodiversity are found in deeper
rock strata, while greater biodiversity and complex organisms are found in shallower rock
strata
– Transition forms which show the transition state from one type of organism to another are
rare
Modification by Descent
– The basic body plans of different plants and animals are similar with various adaptations
for different habitats
In Vertebrates
– Pentadactyl limbs in various vertebrates have different functions but similar structures
– Functions include digging, flying, running, swimming, and climbing
– Shared characteristics
– One proximal bone (humerus)
– Two distal bones (radius/ulna)
– Number of wristbones (carpals)
– Five metacarpals in the palm
– Five phalanges
– Homologous structures - same body plan, different functions - may have come from (a)
shared ancestor/s.
– Divergent evolution: common ancestor develops differently in different environments.
– Analogous structures: same function, different structure
– Convergent evolution: unrelated organisms develop structures with similar functions
Modification within a Species
– Species change within themselves to get to modern day species
– E.g. the evolution of the horse
, Biogeography
– The geographical distribution of extant and extinct species show that closely related
species occur in the same geographical regions.
– New species may form as a result of geographical barriers:
– Large mountain ranges
– Large masses of water
– Small landmasses
– Deserts
– Some regions with similar conditions in different places on the globe contain different
species which are very similar to each other
Genetics
– Closely related organisms have more similarities in their DNA
– Explains the source of variation necessary for evolution
– Shows how characteristics are passed from generation to generation
Comparative Biochemistry
– Most living organisms have similar molecular compositions
– DNA structure
– Coding for protein synthesis/nitrogenous bases
– Process of protein synthesis
– Common set of amino acids
– Metabolic processes/enzymes
– ATP as an energy carrier
– Hox/master control genes determining bodily development
– Phospholipid membranes
Vestigial Structures/Organs
– Structures/organs that have reduced/decreased in size with disuse in some organisms
while others still use them fully indicate common ancestors
Comparative Embryology
– Hypothesis proposing that embryonic development of various vertebrates was very similar
– Proven to be inaccurate, and no longer used to in support of evolution
Development of the Theory of Evolution
Erasmus Darwin
– Ideas influenced his grandson, Charles Darwin
– Proposed that:
– All life on Earth shared a single common ancestor
