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?