History of Life and the Origin of SpeciesMrs. StewartHonors biologyCentral Magnet School
Standards:
CLE 3210.5.3 – Explain how genetic variation in a population and changing environmental conditions are associated with adaptation and the emergence of new species.
Objectives (today, I will…)
Differentiate between biogenesis and spontaneous generation
Differentiate between Charles Darwin and Jean-Baptiste Lamarck
Explain the idea of “natural selection” and determine “fittest”
History of Life
Biogenesis:All living things come from other
living things
Spontaneous Generation:Living things could arise from
nonliving things
Redi’s experiment
Previous idea: Flies were created from rotten meat
Redi: Meat kept away from adult flies would not produce maggots
Spallanzani & Pasteur
Spallanzani – tried to disprove that microorganisms arose from a “vital force” in the air
Pasteur – improved spallanzani’s experiment to eliminate the flaw of “no air”
Ch. 15.1 – 15.2
History of Evolution
Mrs. StewartHonors BiologyCentral Magnet School
What is Evolution?Dictionary:The gradual development of something;
especially from a simple to complex form.Text book:Generally, in biology, the process of change
by which new species develop from pre-existing species over time
Evolution of Dance
18th Century IdeasAbout living species:
About the Earth:
Uniformitarianism
All species were permanent and unchanging.
Earth was only a few thousand years old and unchanging.
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.
Jean-Baptiste Lamarck
French Naturalist1809 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.
Lamarck believed over time, this process led to change in a species.
Lamarck’s Hypothesis
1. Tendency toward perfection - All organisms have an innate tendency toward complexity and perfection, so they are continually changing to be more successful in their environment2. Use and disuse - Organisms can alter their bodies/organs by use or disuse 3. Inheritance of acquired traits - Organisms can pass on those altered body parts/organs to the offspring
Lamarck the Loser
First to develop a hypothesis of evolution
First to realize organisms adapt to their environment
But, Behavior has no effect on inheritable characteristics
Charles Darwin1809 – 1882Naturalist – study of nature
and the natural worldSailed on the HMS Beagle
in 1831Every time the ship
docked, Darwin went ashore to collect plant and animal specimens
Darwin’s observations piqued his interest in the diversity of life he observed.
Darwin even found evidence that suggested species once present on earth had vanished.
Researchers today speculate that 99.9% of all species that ever inhabited earth are now extinct.
Galapagos IslandsThe islands were close together, but had
very different climatesSmallest and lowest islands = hot, dry &
barrenHood Island = sparse vegetation
Higher islands had greater rainfall and a different assortment of plants/animalsIsabella Island = rich vegetation
Land Tortoise shell shapes could be used to identify which island it inhabited
What observations can YOU make about these species of land tortoise?
Pinta Island Tortoise
Isabella Island Tortoise
Hood Island Tortoise
Which island would you predict has only low-lying vegetation?
Pinta Island Tortoise
Isabella Island Tortoise
Hood Island Tortoise
Darwin’s Idea
Darwin observed that the plants and animals varied noticeably among the different Galapagos Islands.
However, Darwin wondered if animals living on different islands had once been members of the same species – originating from the same South American ancestor
Darwin’s FinchesDarwin observed many different types
of “finch” and noticed several different beak shapes.
Why?He began to notice different shaped
beaks were “adaptations” for different food sources
Religion’s RoleDarwin was a devout Catholic
He knew that his ideas, based on what he observed would provoke the catholic church
He debated over what to do for 25 years.
Descent With Modification
The Origin of Species by Means of Natural Selection – 1858
Every species – living or extinct – descended by reproduction from preexisting species
ANDSpecies must be able to change
over time
Natural Selection Mrs. StewartHonors biologyCentral Magnet School
Review
What was Lamarck’s hypothesis?
What did Darwin believe?
Inheritance of acquired traits
Species changed as environment changed – adaptation and survival of the fittest
Standards:
CLE 3210.5.3 – Explain how genetic variation in a population and changing environmental conditions are associated with adaptation and the emergence of new species.
Darwin’s reasoning for Natural Selection
1. Overproduction – more offspring produced than can survive
2. Genetic Variation – within a population, individuals have different traits. New traits may appear spontaneously.
3. Struggle to survive – constant competition may cause some variations/traits to be advantageous
4. Differential Reproduction – Organisms with the best adaptations will survive and reproduce, thus the advantageous adaptations will become most prevelant in the population.
Evolution by Natural Selection
Struggle for existence – each member of a species competes regularly for food, living space and other necessities of life. main needs: Food, water, living
space and ability to reproduceWho wins?
Survival of the FittestHow well suited an organism is to it’s
environmentDoes fittest mean strongest?Does fittest mean in the best shape?
Fitness – the ability of an individual to survive and reproduceThe result of adaptations
Survival of the FittestFittest – the individuals most capable to survive
and reproduce for multiple generations
The traits selected as the most useful for survival and reproduction are determined by the organisms environment
Natural Selection accounts for Descent with Modification as species become better adapted to different environments.
Adaptation vs. Acclimatization
Adaptation - Changes in traits in populations over timeExample: White moth population
becoming a black moth population after 5 generations.
Acclimatization – individual organism changes physiologicallyExample: growing thicker fur in winter
AdaptationsAny inherited characteristic that increases an
organism’s ability to survive and reproduceAnatomical or structural characteristics
Porcupine quills - protectionLonger necks in giraffes – find food
Physiological processesHow a plant performs photosynthesis
Instinctual BehaviorsHunting in packsLiving in burrows
Objectives (today, I will…)
Differentiate between biogenesis and spontaneous generation
Differentiate between Charles Darwin and Jean-Baptiste Lamarck
Explain the idea of “natural selection” and determine “fittest”
Evidence of EvolutionMrs. StewartHonors BiologyCentral Magnet School
Standards:
CLE 3210.5.3 – Explain how genetic variation in a population and changing environmental conditions are associated with adaptation and the emergence of new species.
Descent with Modification
Over long periods of time, natural selection produces organisms with different structures, niches or occupy different habitats than their ancestors.
Each living species has descended, with changes, from other species over time.Result: species today look/act different
from their ancestors
Common DescentLook back: Tigers, panthers and
cheetahs all share a common ancestorLook back further: you will find
ancestors that these cats share with horses, dogs and bats.
Farther back: common ancestors of mammals, birds, alligators and fishes.
Logic: looking far enough back we should find the common ancestor for all living things
Common Descent
Evidence of
Evolution
Fossil Records
Homologous Structures &
Vestigial Organs
Common Descent & Descent w/
Modifications
Comparative Embryology
Fossil Records
Compare fossils from older layers and younger layers and show changes in species over time
Fossils - preserved remains of ancient organisms
Fossil Records
Compare fossils found around the world and we can infer when and where different organisms existed.
Fossils also provide evidence about the environment in which the organism existed and for which the organism adapted
Transitional Species
Fossil records show species which have features that are intermediate between those of hypothesized ancestors and later descendant species
Homologous Body
Structures
Homologous Body Structures
The limbs of reptiles, birds and mammals (arms, wings, legs and flippers) vary greatly in form and function but are all constructed from the same basic bones.
Vestigial Organs – organs/body parts that were once used, but by natural or artificial selection, are no longer necessary
Vestigial OrgansAp
pend
ix
Vestigial Organs
Hip bone in a whale
Vestigial OrgansTa
ilbon
e in
hum
ans
Similarities in Embryology
The early stages, or embryos, of many animals with backbones are very similar.
Does this mean that a human embryo is ever identical to a fish, or a bird embryo?
NOBut, many embryos look especially
similar during early stages of development.
Fish Salamander Tortoise ChickenPig Man
Comparative Embryology
What do these similarities mean?
The same groups of embryonic cells develop in the same order and in similar patterns to produce the tissues and organs of all vertebrates.
Exit Ticket: Socrative.comRoom Number: Stewart 348
Question: How does the environment determine the “fittest” individual?