Unit 5 - Evolution.

La geosfera
Unit 5: Evolution
Unit 10 from the book.

Vocabulary
La geosfera
Fixism: Gene flow:
Evolutionism: Genetic drift:
Trend: Patterns:
To evolve: Hominisation:
Common: Common:
Phylogenetic tree: Phylogenetic tree:
Uphold: Acquired:
2
Brainstorm
Do humans come from

monkey?
1. La
1. geosfera
The concept of evolution: fixism and evolutionism.
The enormous biological variety on Earth is the result of

the evolutionary process and the adaptation of
organisms to different habitats.
Fixist theories: they uphold the idea that the species

that current exists on Earth were created by God in the
form that we can see today, they didnt change. This
theories dominated until the 18th century and their main
proponents were Linnaeus and Cuvier.
4
1. 1. The concept of evolution: fixism and evolutionism.
Cuvier proposed the theory of Catastrophism. According to this

theory Earth had experienced many catastrophes in its history
that led to the disappearance of many species.
George Cuvier (1769-1832) Carl Von Linnaeus (1707-1778)

1. geosfera
La 1. The concept of evolution: fixism and evolutionism.
Evolutionary theories: from the 18th century onwards
several naturalists maintained that the species undergo a
process of transformation that which results in the
appearance of new species.
6
2. Evidence of evolution.
Evolutionary theories propose that the similarities observed

between living things are due to the ancestral relationships between
them:
1. Comparative anatomy (anatomical evidence).
2. Biogeographical evidence.
3. Palaeontological evidence.
4. Biomolecular evidence.
5. Embriological evidence (not in the book).
1. Comparative anatomy: relation between the organs in different

species.
Vestigial organs: were used in the past but not anymore.
Homologous organs: the have the same structure and origin but
different shape and function.
Analogous organs: they have a different origin but the same
function.
Homologous organs
Analogous organs
https://www.youtube.com/watch?v=2N3OPRodRvk
2. Biogeographical evidence: when populations are isolated

they evolve in a more different way.
3.Palaeontological evidence: it
is based on the fossil record,
comparing extinct and current
species in order to identify
similarities and differences.
Archaopteryx
4. Biomolecular evidence: the fact that all living things are

made up by the same type of molecules tell us that we have a
common origin. Also the genetic code, the nucleotide sequence
and metabolic routes.
5. Embriological evidence:
the different forms that an
organism´s embryo displays
during development reflect
the form that their ancestors
had. In the early phases, the
embryo´s of all vertebrates
exhibit many similarities.
Phylogenetic tree
A phylogenetic tree is a diagram that shows the ancestors and the evolutive
relationship between different species, current and extint.
An speciation event is a moment in which the evolutionary lineage

splits, starting two different ways with new species.
Phylogenetic tree
3. Theory of acquired characteristics.
The first evolutionary theory was the the theory of acquired
characteristics or transformism, proposed mainly by J.B. Lamarck
3. Theory of acquired characteristics.
The first evolutionary theory was the the theory of acquired

characteristics or transformism, proposed mainly by J.B.
Lamarck
According to the transformism,
the new environmental
conditions force the species to
develop new characteristics
more adapted to the habitat,
and these characteristics are
inherited by the descendants.
The genetic advanced has showed that the characteristics

developed during life are not passed to the offspring. However
this theory was an important step in the evolutionary thinking.
4. Theory of natural selection.
In the mid-19th century Charles Darwin and Alfred R. Wallace

proposed the Natural selection as a source of biodiversity and
evolution.
https://www.youtube.com/watch?v=JOk_0mUT_JU
According to Darwin, natural selection is based on the following:
Sexual reproduction increases the variability between
individuals.
The struggle for existence between organisms in a population.
Limited resources lead to a struggle to survive, which means
individuals have to compete for the resources they need to stay
alive.
Survival of the best-suited: individuals with advantageous
variations survive and reproduce more successfully.Less well-
suited individuals with a disadvantageous trait do not mature, or
leave fewer descendants. As a result, those traits disappear from
the population
The origin of species as a result of adaptation of organisms
to the environment: with time, an accumulation of modiﬁcations
leads to new breeds and varieties, which eventually results in new
species
https://www.youtube.com/watch?v=Cz6VTtlQksE&t=58s
https://www.youtube.com/watch?v=XucJAhlWLFw
Exercises I.
1. According to Darwin, why do

individuals compete against each
other? What are the the
consequences of this constant
competition?
2. Many species that live in the

Arctic have white feathers or fur.
How would Darwin explain this
fact.
5. Updates on natural selection.
With the advances of genetics, the concept of natural
selection has been broadened, more theories have appeared.
The synthetic or neo-darwinism theory propose that:

- The evolutionary unit is not the individual, but the
population itself.
- This genetic variability is the result of mutations and
recombination processes that take place during sexual
reproduction.
The neutral theory uses the

advances in molecular biology and
claims that:
- Most mutations are neither

beneficial nor disadvantageus,
they are neutral, so natural
selection do not affect them. T. Ohta
- The rhythm of evolution is

constant.
M. Kimura
The puntuated equilibrium theory try to explain the

absence of species in the fossil record. I does not deny
the natural selection but the way in which new species
are produce.
Puntuated equilibrium
The
palaeontologists
N. Eldredge and
S.J. Gould
6. Genetics mechanisms of evolution
The genetic recombination that occurs in organisms with

sexual reproductions lead to a new combination of genes in the
offspring, increasing the variability.
Mutations are random changes in genetic material that mean a

new variant in genes. that occurs in organisms with sexual
reproductions lead to a new combination of genes in the offspring,
increasing the variability.
6. Genetics mechanisms of evolution
Mutations are beneficial, neutral and detrimental. Only the

mutations in the sex cells are passed onto the offspring.
6. Genetics mechanisms of evolution.
Other mechanisms of evolutionary change:

Evolution always occurs at the population level, when the allele
frequency of a certain gene change.
6. Genetics mechanisms of evolution.
7. Speciation and patterns of evolution.
Speciation is the process of formation on new species. It often

happens when it exist reproductive isolation, a group of individuals
can not reproduce with others, splitting the population in two.
It exists different models of speciation.
https://www.youtube.com/watch?v=HPQF9BQnw2A
Exercises II
1. Explain the difference between gene flow and genetic drift.

2. Exercise in the digital book page 217
3. Related to the speciation process order the following
statements:
a) Each group accumulates varions on which natural
selection acts.
b) The difference between the groups become so great
that they evolve into two different species.
c) One or more group of organisms in a population with the
same genetics become isolated.
4. Page 226 ex 47.
The populations of the same species, when are isolated, can evolve in
different ways:
Coevolution: two or more species influence each other´s evolutionary
process.
Divergent evolution: it occurs when species with a common ancestor
evolve differently. Alteration in environmental conditions in which the
organisms live.
● Migration of organisms into different habitats.
● Different mechanisms of adaptations of the organisms for their
survival.
● Genetic changes including mutations. Ex genus Panthera.
Convergent evolution: it occurs in species with different ancestor but they

have evolved to adapt to similar environments. Ex: shark and dolphin.
● Exposure to the same environmental conditions.
● Similar adaptive mechanism to the conditions they need for survival.
● Genetic changes due to mutation occur simultaneously in the different
Coevolution, divergent evolution or convergent evolution?
A B C
D E F
9. Human evolution
Hominisation is the process that describes the progressive transformation of
a given primate into humans
9. Human evolution
Significant changes in hominisation

9. Human evolution
opposable thumb
9. Human evolution
sole´s foot
9. Human evolution
Skull, foramen magnum and development of the brain

9. Human evolution
pg 224
Resources
https://phet.colorado.edu/sims/html/natural-selection/latest/natural-selection_es.html
https://www.youtube.com/watch?v=qt2f5_Pg_QE
https://www.youtube.com/watch?v=8pEitdhI2oY
https://www.youtube.com/watch?v=mZt1Gn0R22Q&t=115s
https://www.youtube.com/watch?v=udZUaNKXbJA&t=354s
Hominisation:
https://www.youtube.com/watch?v=ehV-MmuvVMU&t=67s
https://www.youtube.com/watch?v=HwnB8aCn8yE (animation)
https://www.youtube.com/watch?v=_ANNQKKwWGk
https://www.youtube.com/watch?v=SGxDv7XybSo

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La geosfera

Unit 10 from the book.

Fixism: Gene flow:

Evolutionism: Genetic drift:

Phylogenetic tree: Phylogenetic tree:

Do humans come from

The enormous biological variety on Earth is the result of

Fixist theories: they uphold the idea that the species

Cuvier proposed the theory of Catastrophism. According to this

George Cuvier (1769-1832) Carl Von Linnaeus (1707-1778)

Evolutionary theories propose that the similarities observed

1. Comparative anatomy: relation between the organs in different

2. Biogeographical evidence: when populations are isolated

4. Biomolecular evidence: the fact that all living things are

An speciation event is a moment in which the evolutionary lineage

The first evolutionary theory was the the theory of acquired

The genetic advanced has showed that the characteristics

In the mid-19th century Charles Darwin and Alfred R. Wallace

1. According to Darwin, why do

2. Many species that live in the

The synthetic or neo-darwinism theory propose that:

The neutral theory uses the

- Most mutations are neither

- The rhythm of evolution is

The puntuated equilibrium theory try to explain the

The genetic recombination that occurs in organisms with

Mutations are random changes in genetic material that mean a

Mutations are beneficial, neutral and detrimental. Only the

Other mechanisms of evolutionary change:

Speciation is the process of formation on new species. It often

1. Explain the difference between gene flow and genetic drift.

Convergent evolution: it occurs in species with different ancestor but they

Coevolution, divergent evolution or convergent evolution?

Significant changes in hominisation

Skull, foramen magnum and development of the brain

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