3. What is Evolution
• It means that all living things on Earth are descended
from a common ancestor.
• The great diversity of organisms is the result of more than
3.5 billion years of evolution that has filled every available
niche with life forms.
• The millions of different species of plants, animals, and
microorganisms that live on Earth today are related by
descent from common ancestors.
4. The concepts of common descent and
natural selection were first proposed
by Charles Darwin in his famous book,
The Origin of Species in 1859
5. Evolution, the process by which living organisms diversify and adapt over
time, has captivated scientists for centuries. Understanding the mechanisms
and patterns of evolution is fundamental to various scientific disciplines,
including biology, paleontology, genetics, and ecology. In this essay, we will
explore the diverse array of methods used to study evolution, ranging from
observational studies to sophisticated laboratory techniques.
1.Observation and Field Studies
2.Fossil Record Analysis
3.Comparative Morphology and Anatomy
4.Molecular Genetics and Phylogenetics
5.Experimental Evolution
Methods to study evolution
6. 1. Observation and Field Studies: Observational studies involve direct
observation of living organisms in their natural habitats. Field studies allow
scientists to observe evolutionary processes such as natural selection,
adaptation, and speciation in real-time. Researchers may study population
dynamics, mating behaviors, and ecological interactions to gain insights into
evolutionary patterns. Long-term field studies, such as those conducted on
Galápagos finches by Charles Darwin and modern studies on peppered moths
and Darwin's finches, provide valuable data on evolutionary changes in natural
populations.
7. 2. Fossil Record Analysis: Paleontology utilizes the fossil record to
reconstruct evolutionary history and understand the emergence of
new species over geological time scales. Fossils provide tangible
evidence of past life forms and evolutionary transitions.
Paleontologists analyze fossil morphology, distribution, and
stratigraphic layers to infer evolutionary relationships and
evolutionary trends. Techniques such as radiometric dating and
sedimentary analysis help establish the chronology of evolutionary
events.
8. Fossils:
Traces of long-dead organisms
There are different types of fossils here are just a few.
A body fossil is the actual remains of the organism. The most
common body fossils found are from the hard parts of the body,
including bones, claws and teeth.
9. Types of Fossils
• A cast fossil occurs
when the mold is
filled in by
precipitating
minerals.
• A fossil mold is formed by
the impression left in rock
by the remains of an
organism.
10. Types of Fossils
• A trace fossil consists
of an imprint or mark
left by an organism,
such as a footprint or
a tunnel, in contrast
to a fossil of an
organism's remains.
Scientists sometimes find
unaltered remains. This does
not mean the organism is
unchanged, but that the original
material of the organism has not
been changed to another
substance. The fossil may have
lost water, or color.
11. PALEONTOLOGY = It is the part of
geology that studies fossils. FOSSILS =
They are the remains of living beings or
their activity preserved in rocks.
Fossilization (it is a rare ocurrence)
An organism dies and its body lays on the ground
The soft parts are decomposed
Sediments cover the remains
Diagenesis takes place and the minerals of the sediments substitute
the atoms of the bones, shell…
The sedimentary rock is eroded and the fossil appears uncovered
12. Importance of
fossils
information
A fossil species will only
They provide temporal appear in rocks for a
specific period of time
(when it lived)
They provide
paleoecological
information
Learn about the
environmental
conditions of a
particular age
INDEX FOSSILS
(fósiles-guía): fossils of
species that existed for
short periods of time
over large areas
Trilobites, ammonites
Ammonite Trilobite
14. Dating methods
in geology
Absolute
dating
They determine the
age of the events or
materials
Relative
dating
They put materials or
events in
chronological order
without specifying
exact dates
15. Absolute dating methods: RADIOMETRIC DATING
Method used to date an object by comparing the number of
specific radiactive isotopes it contains
Some atoms lose particles from their nucleus in a process of disintegration.
This process happens at fixed speeds.
16. The speed of disintegration is expressed as the HALF LIFE (T) of a substance. It is
the time required for half of a mass of radiactive isotopes to disintegrate.
(período de semidesintegración)
17.
18. Commonly used techniques
▪ Radiocarbon dating
▪ Uranium–lead (U-Pb) dating
▪ Uranium–thorium (U-Th)
▪ Potassium–argon (K-Ar) dating and argon–argon (Ar-Ar) dating
19. Carbon – 14 Datable Materials:
Charcoal, wood, twigs, seeds, bones, shells, leather, lake
mud, fabrics, soil, hair, pottery, peat, pollen, wall paintings,
corals, blood residues, paper or parchment, resins
21. Carbon-14 is naturally produced in the Earth's atmosphere through a fascinating interaction between cosmic
rays and nitrogen-14. Here's the breakdown:
1. Cosmic Rays: These are high-energy particles originating from outside our solar system. They constantly
bombard the Earth's atmosphere.
2. Interaction with Nitrogen: As cosmic rays crash into the atmosphere, they collide with various molecules,
including those of nitrogen (N₂).
3. Neutron Creation: These collisions sometimes break off neutrons (subatomic particles) from the nitrogen
atoms, creating free neutrons.
4. Carbon-14 Formation: When a free neutron collides with a nitrogen-14 (¹⁴N) atom in the atmosphere, a
fascinating phenomenon occurs. The neutron is absorbed by the nitrogen-14, converting it into a carbon-14 (¹⁴C)
atom and releasing a proton (p):
¹⁴N (neutron) → ¹⁴C + p
5. Conversion to Carbon Dioxide: Newly formed carbon-14 atoms quickly combine with oxygen molecules (O₂)
in the atmosphere, forming carbon dioxide (CO₂):
¹⁴C + 2O₂ → ¹⁴CO₂
6. Distribution and Cycle: This carbon dioxide containing radiocarbon (¹⁴C) enters the global carbon cycle,
circulating through the atmosphere, being absorbed by plants through photosynthesis, and then transferred
through the food chain as animals consume plants or other animals.
Therefore, the production of Carbon-14 in nature is a continuous process fueled by cosmic rays bombarding
the atmosphere. This process maintains a relatively constant ratio of Carbon-14 to the more common, stable
carbon isotope Carbon-12 (¹²C) in the atmosphere and living organisms. This constant ratio is crucial for the
application of Carbon-14 dating in archaeology and other fields.
Origin of Carbon – 14
22. How Radioactive Dating Works:
All living organisms accumulate C-14 while they are alive
Once the organism dies, it stops accumulating
carbon and the C-14 it has slowly decays into N- 14
(nitrogen-14)
Once the organism dies, it stops accumulating carbon and the
C-14 it has slowly decays into N- 14 (nitrogen-14)
We can measure the amount of C-14 left or N- 14
made to date any fossil
23.
24. 14C has a half-life of 5,730
years. In other words, after
5,730 years, only half of the
original amount of 14C remains
in a sample of organic material.
Carbon 14 half life
25. When Living organisms die, they all have the
same amount of carbon-14. When scientists find
fossils they will measure how much carbon-14 it
has left in its body.
28. Limitations of carbon dating
• Carbon dating cannot be used for samples older than 60,000 years.
• The material being dated must have measurable amounts of the parent
or the daughter isotopes.
• Carbon dating can only be done on some materials, hence is not useful
for determining the age of sedimentary rocks, and the method of
carbon dating can be prohibitively expensive.
• Samples can be contaminated by other carbon-containing materials.
• The dates obtained from radiocarbon dating are not infallible, that is,
in general, single dates should not be trusted. Thus, multiple samples
need to be collected and dated.
29. • 3. Comparative Morphology and Anatomy: Comparative morphology
involves the study of anatomical structures across different species to
elucidate evolutionary relationships. By comparing the anatomy of
organisms, researchers can identify homologous structures
(structures derived from a common ancestor) and analyze patterns of
divergence and convergence.
30. Similarities among related organisms:
Comparative Anatomy:
The study of Homologous
traits (ex. forearms)
features in different
species that are similar
because those species
share a common ancestor.
Homologous structures:
31. Embryonic development is also strikingly
similar among related organisms.
Comparative Embryology:
32. ANALOGOUS
·Dissimilar in anatomy
·Similar Functions
·Develop in unrelated animals
·Not inherited from a common ancestor
·Developmental pattern not similar
·Dissimilar in structure and origin
·HOMOLOGOUS
·Similar in anatomy
·Dissimilar functions
·Develop in related animals
·Inherited from a common ancestor
·Developmental pattern is similar
·Similar in structure and origin
Homologous structures share a similar embryonic origin; analogous organs have a similar function.
33. VESTIGIAL STRUCTURES are features that were adaptations for an organism’s
ancestor but have evolved to no longer perform their original function due to a
change in the organism’s environment.
Goose bumps
C Hind leg in whale
34. 4. Molecular Genetics and Phylogenetics: Advancements in
molecular biology have revolutionized our understanding of
evolution. Molecular genetics techniques allow researchers to
study DNA sequences, genetic variation, and gene expression
patterns across populations and species. Phylogenetics, the
study of evolutionary relationships based on molecular data,
reconstructs evolutionary trees (phylogenies) to depict the
evolutionary history of organisms. Methods such as DNA
sequencing, polymerase chain reaction (PCR), and
bioinformatics tools play crucial roles in phylogenetic analysis.
35. • Molecular Biology: is the strongest evidence for
evolution. Not even known in Darwin’s time, it
involves comparing the DNA of different species to
determine their relatedness.
• Just like our forelimbs or embryos are similar, so are
our genes.
• Genes are also homologous structures.
Evolution comes from molecular biology
37. And what is DNA?
The function of DNA is to store and transmit the
genetic information that tells cells which proteins
to make and when to make them
38. Does our DNA look like
the DNA of other species?
40. 5. Experimental Evolution: Experimental evolution involves
manipulating environmental conditions or genetic factors in
controlled laboratory settings to observe evolutionary
changes over short time scales. Researchers can study
evolution in action by subjecting organisms to selective
pressures, mutation rates, or reproductive strategies. Model
organisms like fruit flies (Drosophila melanogaster) and
bacteria (Escherichia coli) are commonly used in
experimental evolution studies due to their short generation
times and well-understood genetics.
41. Experiments also show that populations
can evolve. For example, biologist John
Endler conducted experiments with the
guppies of Trinidad that clearly show
selection at work. Female guppies prefer
colorful males as mates. However, colorful
males are also more likely to be eaten
by predators because they are easier to
spot. Some parts of the streams where the
guppies live have less dangerous predators
than others, and in these locations the
males are more colorful. In locations
where there are more dangerous
predators, males tend to be less
colorful. Of course, the likely explanation
for this observation is that the guppy
population in each area has evolved in
response to the competing preferences of
females and predators present in that
particular environment.
