5.1_Intro to Evolution Lesson_3/27

Biodiversity

The variety of organisms in an area, by species, genes, populations, and communities, also called biological diversity.

Where did life begin?

endosymbiotic theory-

proposed that the organelles of eukaryotic cells were

once prokaryotic cells that have been engulfed by a
larger prokaryotic cell

evidence: mitochondria & chloroplasts reproduce like

bacteria

takeaway:

Life started simple
and became more
complex over time.

Explaining Endosymbiotic Theory: https://www.youtube.com/watch?v=FGnS-Xk0ZqU

Multiple Choice

The Endosymbiotic Theory explains

• the origin of prokaryotes

• how bacteria lives

• the origin of eukaryotes

• how species develop

Multiple Choice

Which of the following is evidence to support the endosymbiotic theory?

• Mitochondria and chloroplasts have their own DNA, which is similar to prokaryotic DNA.

• Fossil evidence shows that the first forms of life were prokaryotic cells.

• All eukaryotic cells have a double-layered membrane composed of phosplipids and proteins.

• Prokaryotes have the same number and types of enzymes as eukaryotes.

EARLY IDEAS ABOUT EVOLUTION

Evolution is a change in the inherited characteristics of

a group of organisms over generations.

 Evolutionary theory is the collection of scientific

facts, observations, and hypotheses that attempt to
explain the diversity of life on Earth.

 Modern scientists define

evolution as a heritable
change in the
characteristics within a
population from one
generation to the next.

Dalmanites myops, a trilobite found in 420-million-year-old

limestone rock

EARLY IDEAS ABOUT EVOLUTION

Much of today’s understanding of evolution is based

on Charles Darwin’s work in the 1800s.

However, Darwin did not

come up with the idea of
evolution himself.

Many other scientists

contributed important
ideas to the study of
evolution.

Alfred Russell Wallace

 Father of Biogeography

 Interested in the geographic

distribution of species

 Worked in the Amazon Rainforest

 Worked in Indonesian Archipelago

 The Wallace Line

 Co-discovered Natural Selection

with Darwin (though 30 years later)

 Stimulates Darwin to publish his work

The Origin of Species (1859).

EARLY IDEAS ABOUT EVOLUTION

 Jean-Baptiste Lamarck, a French naturalist, put forward his own

theory for how evolution works.

 He proposed that organisms inherited changes caused by use or

disuse in its parents.

 For example, if a parent giraffe

stretches its neck to get at leaves on tall
trees, its descendants are born with
longer necks, and so giraffes evolve
over generations to have long necks.

 While his theory was subsequently

disproven, aspects of his idea still float
around today.

Multiple Select

Lamarck's Theory state...

• Throughout their lifetimes animals improved themselves

• Changes are caused by the struggle to survive

• Acquired traits are passed to offspring

• Law of Use / Disuse

Multiple Choice

Which scientist thought that if you had tatoos you could pass them on to your children?

• Lamarck

• Darwin

EARLY IDEAS ABOUT EVOLUTION

 In 1831, English naturalist Charles

Darwin completed his college studies
and joined the crew of the HMS
Beagle for a 5-year trip around the
world.

 This trip would become one of the

most important voyages in the
history of science.

 On this voyage, Darwin would make

observations and collect evidence
that would lead him to propose his
theory of evolution about the way
life changes over time.

EARLY IDEAS ABOUT EVOLUTION

 During his voyage, Darwin made

many observations.

 For example, many of the plants

and animals he observed were
well-suited to the environment in
which they were living.

 He noted that adaptations seen in

desert organisms would not be
seen in organisms living in a
rainforest.

Adaptations are characteristics of organisms that enhance their

survival and reproduction in specific environments.

EARLY IDEAS ABOUT EVOLUTION

One key observation that Darwin made was the variation
of life.Variation is differences in traits among organisms.
The classic example is the variation of beaks in finches
(birds) in the Galapagos Islands.

These are all finches from the
Galapagos Islands. Notice that
their beaks vary in size, shape,

and thickness.

Why do you think
these finches would

have different

beaks?

DARWIN’S RETURN
HOME

•Darwin has already gained national recognition
before he returns

•1000’s of specimens of all types of living
things and fossils had been sent back to the
UK throughout his journey

•Many scientists and naturalists were already
studying these

•Darwin would spend the next ~30 years reflecting
on what he observed

•In 1858 Darwin would receive a letter from Alfred
Wallace (Working in Indonesia)

•Wallace conveyed the same concept of
Natural Selection in his field work.

•Charles Lyell encourages Darwin to publish
despite the controversy of his theory.

•Darwin and Wallace jointly present their findings
and both are recognized with discovering
evolution

EARLY IDEAS ABOUT EVOLUTION

 Darwin noted the similarities

and differences among many
different organisms.

 He became convinced that

organisms had changed over
time.

 Darwin noted that the

organisms found on each island
(Galapagos Islands) had special
adaptations that allowed them
to survive only on that island.

saddle-back tortoises

Pinta Island tortoises have shells that rise in the front like a saddle.

dome-shaped tortoises

The majority of tortoises on Isabela Island have dome-shaped shells.

Natural selection is a process in which organisms better suited to their environment are able to survive and reproduce more offspring

These favorable traits and characteristics are then passed on to their babies through a process called inheritance.

Multiple Choice

Charles Darwin’s observation that finches of different species on the Galápagos Islands have many similar physical characteristics supports the hypothesis that these finches.  

• have the ability to interbreed. have the ability to interbreed.

• acquired traits through use and disuse.

• all eat the same type of food.

• descended from a common ancestor.

Multiple Choice

Lamarck’s ideas about evolution include the concept that differences among the traits of organisms arise as a result of

• continual increases in population size.

• the actions of organisms as they use or fail to use body structures.

• an unchanging local environment.

• the natural variations already present within the population of organisms.

Multiple Choice

Darwin theorized that individuals having an advantage due to their traits or abilities will be more likely to survive and reproduce.  This theory is known as

• evolution

• speciation

• adaptation

• natural selection

Multiple Choice

Which of the following ideas is supported by Darwin’s observation of local variation among tortoises in the Galápagos Islands? 

• artificial selection

• adaptation

• acquired characteristics

• tendency towards perfection

Multiple Choice

Darwin wrote that organisms with traits that are best suited to the environment will ________________

• increase in number

• become extinct

Multiple Choice

What characteristic did Darwin observe about the finches on the Galapagos Islands?

• Their feathers 

• Genotypes 

• Their beaks

• Their body sizes

Let’s Visit the Galapagos Islands!

 Task: Today, we will take a field

trip to the Galapagos Islands via
Google Earth.

 You will observe the fauna

(animals) and flora (plants) on the
different islands to get an idea of
what Darwin saw in 1835.

 Then, you will pretend to be

Darwin and create a postcard to
send back to your family in
England.