Download History of Life and Evolution Notes – part I History of Life Biogenesis

History of Life and Evolution Notes – part I
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History of Life
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Biogenesis:
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All living things come from other living things
Spontaneous Generation:
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Living things could arise from nonliving things
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Redi’s experiment
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Previous idea: Flies were created from rotten meat
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Redi: Meat kept away from adult flies would not produce
maggots
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Spallanzani – tried to disprove that microorganisms arose from a “vital
force” in the air
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Pasteur – improved spallanzani’s experiment to eliminate the flaw of
“no air”
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What is Evolution?
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Dictionary:
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The gradual development of something; especially from a simple to complex
form.
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Text book:
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Generally, in biology, the process of change by which new species develop from
pre-existing species over time
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18th Century Ideas
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All species were permanent and unchanging
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The earth was only a few thousand years old and unchanging
Uniformitarianism
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Idea by Charles Lyell that said geologic processes happed slowly over time and that
some features of the Earth may take millions of years to form.
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Jean-Baptiste Lamarck
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French Naturalist
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1809
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Lamarck’s Hypothesis: by selective use or disuse of organs, organisms acquire or lose
certain traits. These traits could then be passed on to their offspring.
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Lamarck believed over time, this process led to change in a species.
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Tendency toward perfection - All organisms have an innate tendency toward
complexity and perfection, so they are continually changing to be more
successful in their environment
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Use and disuse - Organisms can alter their bodies/organs by use or disuse
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Inheritance of acquired traits - Organisms can pass on those altered body
parts/organs to the offspring
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Lamarck the Loser – he was wrong!
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First to develop a hypothesis of evolution
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First to realize organisms adapt to their environment
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But, Behavior has no effect on inheritable characteristics
Charles Darwin
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1809 – 1882
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Naturalist – study of nature and the natural world
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Sailed on the HMS Beagle in 1831
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Every time the ship docked, Darwin went ashore to collect plant and animal specimens
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Darwin’s observations piqued his interest in the diversity of life he observed.
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Darwin even found evidence that suggested species once present on earth had
vanished.
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Researchers today speculate that 99.9% of all species that ever inhabited earth are now
extinct.
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Galapagos Islands
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The islands were close together, but had very different climates
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Smallest and lowest islands = hot, dry & barren
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Hood Island = sparse vegetation
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Higher islands had greater rainfall and a different assortment of plants/animals
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Isabella Island = rich vegetation
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Darwin’s Idea
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Darwin observed that the plants and animals varied noticeably among the different
Galapagos Islands.
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However, Darwin wondered if animals living on different islands had once been
members of the same species – originating from the same South American ancestor
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Descent With Modification
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The Origin of Species by Means of Natural Selection – 1858
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Every species – living or extinct – descended by reproduction from preexisting species
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AND
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Species must be able to change over time
Darwin’s reasoning for Natural Selection
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Overproduction – more offspring produced than can survive
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Genetic Variation – within a population, individuals have different traits. New traits may
appear spontaneously.
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Struggle to survive – constant competition may cause some variations/traits to be
advantageous
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Differential Reproduction – Organisms with the best adaptations will survive and
reproduce, thus the advantageous adaptations will become most prevelant in the
population.
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Evolution by Natural Selection
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Struggle for existence – each member of a species competes regularly for food, living
space and other necessities of life.
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Survival of the Fittest
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How well suited an organism is to it’s environment
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Does fittest mean strongest?
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Does fittest mean in the best shape?
Fitness – the ability of an individual to survive and reproduce
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The result of adaptations
Fittest – the individuals most capable to survive and reproduce for multiple generations
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The traits selected as the most useful for survival and reproduction are determined by
the organisms environment
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Natural Selection accounts for Descent with Modification as species become better adapted to
different environments.
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Adaptation vs. Acclimatization
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Adaptation - Changes in traits in populations over time
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Example: White moth population becoming a black moth population after 5
generations.
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Acclimatization – individual organism changes physiologically
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Example: growing thicker fur in winter
Adaptations
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Any inherited characteristic that increases an organism’s ability to survive and
reproduce
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Anatomical or structural characteristics
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Porcupine quills - protection
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Longer necks in giraffes – find food
Physiological processes
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How a plant performs photosynthesis
Instinctual Behaviors
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Hunting in packs
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Living in burrows