2. At the end of this lessons, you will be able to:
define biodiversity and evolution;
cite the contributions of Charles Darwin to the theory of
evolution;
account for the evidence of evolution;
explain how biodiversity and evolution affect life;
demonstrate how biodiversity and evolution help an
ecosystem to function;
explain the role of natural selection in the evolutionary
process; and
relate evolution and speciation.
3. Assess Your Prior Knowledge
What is biodiversity?
What is evolution?
How is biodiversity and evolution related to each
other?
5. Charles Darwin
and Evolution
In the early 1800s, French naturalist Jean-
Baptiste Lamarck developed a more concrete
theory about organic evolution. He stressed
two important theme in his work.
First, he stated that animals adapt to the
changes in the environment. He cited that
giraffes necks elongate as a result of them
trying to reach leaves in higher places.
Second, bodies and all their different parts
make it probable for the organic movement
in animals, and that life (as how it came to be)
is organized and structured in an orderly
manner.
6. Charles Darwin and Evolution
Lamarcks ideas about the relationship of environment and
evolution helped set the stage for Darwins theory of evolution.
Charles Darwin was born in 1809, the same year that Lamarck
published his ideas on evolution. At the age of 22, Darwin
ventured on an expedition collecting thousands of specimens,
fossils, and other living animals and plants.
After five years of voyage, Darwin strongly questioned the
belief that Earth and organisms are unchanging and have been
specifically created a few thousands of years prior.
7. Charles
Darwin and
Evolution
He believed that Earth was indeed very old and
constantly changing.
Throughout the years and after writing several essays,
Darwin offered a great deal of evidence supporting
evolution.
He described his theory of natural selection, which
supported and provided an explanation of how evolution
occurs.
8. Evidence and
Evolution
Darwins On the origin of Species
paved the way of continuing knowledge
and biological research up to date.
Most of the evolutionary evidences
were grouped in the following
categories: fossil records, biochemical
evidence, comparative anatomy, and
observable events.
Fossil records. Darwin collected
traces and remains of organisms that
lived long ago. Fossils are usually found
in the sedimentary layers which means
the more the layers, the more
evidence there is of different
organisms.
9. Evidence and
Evolution
Biochemical evidence. The
nitrogen base sequences in the
genetic code are the same in
almost all organisms.
Comparative anatomy.
Comparative anatomy is seen
mainly in the biological structure
of animals. Most have similar
structures but have different
functions.
Observable events. Changes
have been observed in species
over time. These observable
changes show that evolution is an
ongoing process.
10. What is Evolution?
Evolution is defined as any change in the inheritable traits within a certain
population across generations.
These inheritable traits pertain to physical aspects such as color of petals in
flowers, spots on the wings of butterflies, or instinctive behaviours like migration
patterns of animals, among others.
DNA plays an important role in the evolution process. Changes in the genetic code
affect the characteristics and traits in the succeeding generations. As the certain
traits are manifested and are carried on in the next generations, evolution can be
observed.
12. Buzz Session
Divide the class into two groups.
Create a diagram of how you are connected to
the other life-forms (biodiversity) in your
locality.
Write the benefits derived from biodiversity.
After 10 minutes, each group will have a
representative to discuss the diagram.
13. Natural
Selection
Darwin recognized that all species produced quite a
number of offspring.
He reasoned that organisms possessing adaptive
characteristics have a better chance to survive and
reproduce, compared to individuals who do not have
such characteristics.
Darwin sought the basic and central mechanism of
evolution of reproduction in a process called natural
selection.
14. Natural
Selection
The environment plays an
important role in filtering
changes and variations in traits.
Favored traits are being
expressed compared to
unfavored traits which become
less and unlikely expressed in
the succeeding generations.
Natural selection can be
summed up through a famous
Filipino line: Matira ang
matibay.
Artificial selection is the
selective breeding of
domesticated plants and animals
with desirable characteristics.
15. Natural Selection
Genetic variation is extensive in most populations. It is
defined as the difference between cells, individual
organisms, and/or groups of organisms of any species.
caused by their genotypic and phenotypic variation.
Variation may be expressed largely in physical appearance
but can also be observed in behavior, metabolism, or mode
of reproduction.
Factors that affect genetic variation can be linked to
mutation, which is the permanent change in the chemical
structure of a gene.
16. Speciation
Most of Darwins theory of
evolution focused on natural
selection and the gradual
adaptation of a population in a
given environment
(microevolution).
Speciation is the evolutionary
process in which new species arise.
It is the process wherein a group
of one species will acquire new
characteristics, and eventually
make an entirely species.
17. Related
Concepts to
Speciation
Species
Species comes from the Latin word specio for
kind or appearance, as we can easily observe and
learn to distinguish between the different kinds of
animals and plants.
Taxonomy
Taxonomy is a branch of biology that deals with
naming and classifying the diverse forms of life.
Carolus Linneaus, the father of taxonomy,
introduced a binomial system of naming organisms
the Linnaean classification which is still used at
present.
18. Related Concepts to
Speciation
The two-word name given to an organism, also known as
scientific name, consists of the genus and species where
an organism belongs. In Zea mays, the scientific name of
corn, Zea is the genus and mays is the species. The
species, therefore, occupies the lowest taxonomic rank in
the biological classification of living things.
Biological Species Concept
The biological species concept views species as a
population or a group of populations whose members have
the ability and potential to interbreed and produce fertile
offspring.
19. Related
Concepts to
Speciation
Other Species Concepts
Morphological species concept is how scientists were
able to identify more than 1.8 million species. Scientists
make use of measurable phenotypic rates.
Ecological species concept identifies species based on
the ecological environments or niche.
Polygenic species concept defines organisms and
species based on unique genetic history. Biologists
compare a species genetic code and physical
characteristics with other organisms.
20. Related
Concepts to
Speciation
Adaptive radiation is a process wherein the
evolution of species from a common ancestor
diversify rapidly into different new forms due to
changes in the environment.
Being exposed to a new environment makes new
resources available, creating and opening various
opportunities and challenges for the survivors.
The final mechanism of speciation is the tempo of
speciation. Two models have developed for
interpreting and analysing evolutionary patterns. One
model indicates that differences in population
gradually evolve as a result of organisms adapting to
their environments. The formation of new species
gradually evolve from their parent or ancestor.
21. Related Concepts to Speciation
Gradualism is a slow, gradual accumulation of changes
over time. Over a short period of time, it is difficult to
notice.
In punctuated equilibrium, the change comes on spurts.
There may be period of no very little change then all of a
sudden huge changes take place through mutations.
Mutations are changes in the DNA that can be passed on
to succeeding generations.
23. Earth is home to a large number of diverse organisms.
Organisms evolve and adapt in many ways to survive in
their ever-changing environment.
How does the environment influence their evolution and
behavior?
In this chapter, you will learn how everything in the
natural world is connected and how living and nonliving
things work together to achieve stability.
24. In this chapter, you will find answers to the following questions:
1. What impact do my actions have in an ecosystem?
2. How do the different interactions of living and
nonliving things affect the ecosystem?
3. What role do humans play in an ecosystem?
25. At the end of this chapter, you will be able to:
define what an ecosystem is;
identify the components of ecological structures in an
ecosystem;
explain how diversity contributes to stability and survival;
cite examples of what helps and what disrupts the interaction
in an ecosystem;
analyze how the human population affects the different
ecosystems; and
apply the knowledge of biodiversity in the maintenance of an
ecosystem and vice versa.
26. Introduction: Ecosystem Structure
The interaction of living things in the physical
environment consists an ecosystem.
In an ecosystem, the flow of energy and matter moves
in one direction. The light coming from the sun is the main
source of energy for organisms living on Earth.
This radiant energy is used by plants to convert
inorganic compounds, such as carbon dioxide, and water,
into energy-rich compounds through photosynthesis.
27. Plants and other photosynthetic organisms can manufacture
their own food, they are called producers or autotrophs.
Examples of producers: phytoplankton in the ocean and algae
in the pond
Some producers called chemosynthetic autotrophs
synthesize organic compounds without the aid of sunlight.
They make their own food using the dissolved chemicals from
hydrothermal vents found on the ocean floor.
Consumers or heterotrophs are organisms that feed mainly
on producers because they cannot make their own food.
For instance, in a cornfield, corn crops are the producers and
the cutworms who feed on the leaves and stems are the
consumers.
28. A food chain illustrates the flow of energy and matter
in a given ecosystem.
For example, a grasshopper mainly feeds on leaves from
a cornstalk. The grasshopper in turn is devoured by the
maya bird, which is also a consumer. These organisms will
die, and their remains are broken down by decomposers
like bacteria and fungi.
The position an organism occupies in a food chain is
called a trophic level.
The first trophic level in a food chain are comprised of
the producers, and is typically composed of plants and
other autotrophic organisms.
29. The second trophic level is mainly composed of herbivores, or
organisms that feed only on plants. Since the herbivores feed
on producers directly, they are known primary consumers.
The third and fourth trophic levels in a food chain are either
comprised of carnivores (organisms that only eat meat) or
omnivores (organisms that feed on both plants and animals).
Depending on which organism they eat, they can either be
secondary consumers (those that feed on primary consumers)
or tertiary consumer (those that feed on the secondary
consumers).
Scavengers are consumers that feed on the tissues of dead
animals. Their trophic level in a food chain is highly dependent
on what they consume.
30. Decomposers such as fungus or bacterium, feed on dead
organic matter from all trophic levels. As decomposers
feed, dead organic matter is transformed and broken
down into simpler nutrients. These nutrients are returned
into the soil or water where the producers can cause
them again. This recycling process is very important to all
members of the food chain.
