evolution in science

1. Evolution
By Govinda Sunar

2. Evolution
• Birth of new organisms from pre-existing ones.
• It is gradual change. Take long time
• We can just imagine.
• The process of formation of new organisms from old organisms
over a long period of time

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• Evolution is a gradual change over time.
• There are two kinds:
• Geological – a change in the earth over time
• Organic – a change in species over time

4. Organic evolution
It was proposed by Charles Darwin
Organic evolution means the present complex life has evolved from an
earlier simpler form of life by gradual changes.
DNA alteration happen over long time.

5. Evidence of organic evolution
• Evidence from the study of fossils
• Evidence from comparative morphology and anatomy
• Embryological evidence
• Evidence from the study of vestigial organs
• Evidence from the bridge organisms or connecting links

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Evidence from the Past - Fossils
• A fossil is any trace or remains of an organism that has
been preserved by a natural process.
• Most fossils are in sedimentary rock which forms layers.
• If the layers are undisturbed the oldest is on the bottom
and the youngest on top. Therefore, the oldest fossils are
found in the bottom layer.
• This tells you which fossils are older.

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There are sequences in the fossil record that indicate that
later species developed from earlier ones through a
series of gradual changes passed on from generation to
generation.
These occurred over millions of years in the species. The
fossil record is considered the strongest evidence of
evolution.

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Evidence from Living Organisms
• The classification system that
we use is based on
similarities and differences in
anatomy, embryological
development, and
biochemistry.
• Similarities indicate a
common ancestor. The more
similarities between
organisms the more closely
related they are.

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Comparative anatomy
• Vestigial structures – parts that are reduced in size and
have little or no function.
• Human appendix, tail bone, wisdom teeth and muscles that
move the ears and nose
• Whale hip and leg bones

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Homologous Structures
• Parts that have similar structures and development
(are built the same way) but have different functions:
• Human arm
• Cat leg
• Whale flipper
• Bat wing
• Indicates a common ancestor

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Analogous Structures
• Parts that have the same function but a different
structure and development (they are made
differently):
• Bird wing
• Insect wing
• Indicates evolution along different lines

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Embryology
• The embryos of closely related species show similar
patterns of development.
• As development continues the
embryo resembles
the adult.
• The longer the embryos
resemble each other, the closer
related they are.

13. Connecting links
• The organism having the characteristics of two or more groups of
organisms is known as a bridge animal or connecting links

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Comparative biochemistry
• The ability to read the amino acid sequence of proteins and
the DNA of an organism letter by letter has enabled
biologists to confirm evolutionary relationships.
• The more closely related organisms are, the
greater the biochemical similarities will be in the
sequences of DNA, proteins, and enzymes.

15. 1.Which of the following is a form of evidence for evolution that involves
the study of anatomical similarities in different species?
2.a) Homologous structures b) Fossils c) Analogous structures d) Vestigial
organs
3.The study of fossils is significant in providing evidence for evolution
because:
a) It shows that species do not change over time.
b) It provides a record of extinct species and transitional forms.
c) It directly reveals the genetic makeup of ancient organisms.
d) It confirms the occurrence of sudden and unrelated changes in species.
1.Which of the following statements best describes a vestigial organ?
a) An organ that serves a crucial function in a species' survival.
b) An organ that has undergone recent adaptive radiation.
c) An organ that has no apparent function but resembles functional organs in
related species.
d) An organ that was once functional but has lost its original purpose over

16. 1.What is the primary reason that comparative embryology is considered
evidence for evolution?
a) Embryos of all species look identical during development.
b) Embryos show significant differences that cannot be explained by evolution.
c) Similarities in early embryonic stages suggest common ancestry among
species.
d) Embryos directly resemble the adult forms of their respective species.
1.The concept of homology is best exemplified by:
a) The wings of bats and the wings of birds.
b) The fins of fish and the flippers of dolphins.
c) The beaks of different bird species.
d) The eyes of insects and the eyes of mammals.
1.Which of the following is an example of convergent evolution?
a) Dolphins and sharks having similar body shapes for streamlined swimming.
b) Dogs and wolves sharing a common ancestor.
c) Humans and chimpanzees having a common genetic ancestor.
d) Birds and bats both having wings for flight.

17. 1.The term "biogeography" refers to the study of:
a) Biochemistry of different species.
b) Geological formations in different regions.
c) Distribution of species across geographic regions.
d) Evolutionary relationships between different species.
1.Which mechanism of evolution involves the accumulation of small genetic
changes over long periods of time?
a) Genetic drift b) Bottleneck effect c) Punctuated equilibrium d) Gradualism
1.A scientist studying the evolution of antibiotic resistance in bacteria is
examining which type of evolutionary mechanism?
a) Genetic drift b) Natural selection c) Gene flow d) Mutation
1.Which of the following is an example of a prezygotic reproductive isolation
mechanism?
a) Two bird species producing hybrid offspring that are sterile.
b) Two plant species producing flowers with different colors.
c) Two frog species mating at different times of the year.
d) Two fish species sharing the same breeding grounds

18. 1.What is organic evolution?
• Organic evolution is the process by which living organisms change over
time through the process of natural selection.
2.What are the different types of evidence for organic evolution?
• There are five main types of evidence for organic evolution:
• Fossil record
• Comparative anatomy and morphology
• Comparative embryology
• Biogeography
• Molecular biology

19. 3.What is the fossil record?
• The fossil record is a collection of preserved remains of organisms that lived
in the past. The fossil record provides evidence of the evolution of life over
time.
4.What is comparative anatomy and morphology?
• Comparative anatomy and morphology is the study of the similarities and
differences in the anatomy and morphology of different organisms. This
evidence shows that organisms that are closely related have similar body
structures, while organisms that are more distantly related have more
different body structures.
5.What is comparative embryology?
• Comparative embryology is the study of the development of embryos of
different organisms. This evidence shows that embryos of different
organisms have similar features early in development, but these features
become more different as the embryos develop.

20. 6.What is biogeography?
• Biogeography is the study of the distribution of plants and animals on
Earth. This evidence shows that organisms are distributed in a pattern
that can be explained by their evolutionary history.
7.What is molecular biology?
• Molecular biology is the study of the structure and function of
molecules in living cells. This evidence shows that organisms share
many similarities in their DNA and proteins, which is evidence of
their common ancestry.
8.What is a homologous organ?
• A homologous organ is an organ that has the same basic structure in
different organisms, even if it performs different functions. For
example, the forelimbs of humans, dogs, and bats are all homologous
organs.

21. 9.What is an analogous organ?
• An analogous organ is an organ that has a similar function in different
organisms, but has a different basic structure. For example, the wings
of birds and insects are analogous organs.
10.What is a vestigial organ?
• A vestigial organ is an organ that has lost its original function over
time. For example, the appendix in humans is a vestigial organ.

22. 11.What is the theory of natural selection?
• The theory of natural selection is the process by which organisms that
are better adapted to their environment are more likely to survive and
reproduce, passing on their genes to the next generation.
12.What is mutation?
• A mutation is a change in the DNA of an organism. Mutations can be
caused by environmental factors, such as radiation, or they can be
spontaneous.
13.What is gene flow?
• Gene flow is the movement of genes between populations of
organisms. Gene flow can occur through migration, hybridization, or
artificial selection.

23. 14.What is genetic drift?
• Genetic drift is the random change in the frequency of genes in a
population. Genetic drift can occur due to small population size or
founder effects.
15.What is speciation?
• Speciation is the formation of new species from a single ancestral
species. Speciation can occur through a variety of mechanisms,
including geographic isolation, reproductive isolation, and natural
selection.
16.What is punctuated equilibrium?
• Punctuated equilibrium is a theory of evolution that states that most of
the evolutionary change in a lineage occurs in short bursts, separated by
long periods of relative stability.

24. 17.What are the challenges to the theory of evolution?
• There are a few challenges to the theory of evolution, such as the origin of
life, the Cambrian explosion, and the lack of transitional fossils. However,
these challenges have been addressed by scientists, and there is
overwhelming evidence that supports the theory of evolution.
18.What is the importance of the theory of evolution?
• The theory of evolution is important because it helps us to understand the
diversity of life on Earth and how it has changed over time. It also helps us
to understand our own place in the natural world.
19.What are the ethical implications of the theory of evolution?
• The theory of evolution has some ethical implications, such as the debate
about abortion and stem cell research. However, these implications are
complex and there is no consensus on how they should be resolved.
20.What are the future directions of research on evolution?
• Future research on evolution is likely to focus on areas such as the origin of
life, the evolution of behavior, and the evolution of human beings

25. Lamarck’s theory of evolution

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Lamarck’s Theory of Evolution
• Jean-Baptiste Lamarck, 1809
• One Of First Scientists To
Understand That Change
Occurs Over Time
• Stated that Changes Are
Adaptations To Environment
acquired in an organism’s
lifetime
• Said acquired changes were
passed to offspring

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Lamarck’s Theory of Evolution
• Idea called Law of Use
and Disuse
• If a body part were
used, it got stronger
• If body part NOT used,
it disappear

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Lamarck’s Theory of Evolution
• Inheritance of Acquired Characteristics
• Proposed That By Selective Use Or Disuse Of Organs, Organisms
Acquired Or Lost Certain Traits During Their Lifetime
• These Traits Could Then Be Passed On To Their Offspring
• Over Time This Led To New Species

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Lamarck’s Theory of Evolution
• Use & Disuse - Organisms
Could Change The Size Or
Shape Of Organs By Using
Them Or Not Using Them
• Blacksmiths & Their Sons
(muscular arms)
• Giraffe’s Necks Longer from
stretching)

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copyright cmassengale

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Lamarck’s Theory of Evolution
• Inheritance Of Acquired Traits
• Traits Acquired During Ones Lifetime Would Be Passed To Offspring
Clipped ears of dogs could be passed to offspring!

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Lamarck’s Theory of Evolution
• Tendency Toward Perfection
• Organisms Are Continually Changing and Acquiring Features That
Help Them Live More Successfully In Their Environment
• Example: Bird Ancestors Desired To Fly So They Tried Until Wings
Developed

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Lamarck’s Mistakes
• Lamarck Did NOT Know how traits were inherited
(Traits are passed through genes)
• Genes Are NOT Changed By Activities In Life
• Change Through Mutation Occurs Before An
Organism Is Born

34. Darwinism
• English Naturalist and geologist Charles Robert Darwin.
• Darwin proposed regarding how evolution occurs is known as Darwinism.
• Theory of Darwin summarized in the following points.

35. Overproduction in the biosphere
• All organisms reproduce in large number of offsprings but
population remains fairly constant due to the struggle
between members of the same species or different species for
food space and mate

36. Struggle for existence
• The struggle of any organismT with
other for nature, food, habitat and
mating is called struggle for
existence.
• Types of struggle
• Intraspecific struggle:s struggle with
the species of same kinds
• Interspecific struggle-struggle with
the other species
• Struggle with nature-struggle with
climate , weather natural disasters

37. Variation and heredity
•The different in the structural and behavioral
characteristics of organisms is called
variation.

38. Natural selection
• Variations occurs in every organisms
• variation are two types favourable and
unfavourable
• Organisms having favorable variation flourish
and reproduce heathy organisms. which is
select by environment. Having unfavourable
variation were disappear.
• The process in which organisms with suitable
variations survive and those with unsuitable
variation die is called natural selection.

39. Origin of new species
• Long lasting variation rise to new characteristics, behaviours and
abilities.
• Finally organisms become different.
• In this way new species are evolved.

40. Criticism of Darwinism
• No scientific proven-it cannot observed directly
• Only Variations do not create new species.
• Darwin’s theory can’t explain the existance of vestigial
organs
• Unable to explain how variation occurs.

41. Variation and mutation
• No two organisms are identical in this world
• Organisms differ from each other
genetically, physically, behaviourally,
mentally and psychologically.
•The difference in genotype and
phenotype of the organisms in
each successive generation is
known as variation.

42. Major causes of variation
•Hereditaroy variation-variation
cause by the gene of parental
gametes is called hereditary
variation.
•70-80% variation occurs from
heredity in human beings.

43. Environmental Variation
• Variation caused by environmental factors like
climate nutrition, lifestyle, culture etc is known as
environmental variation.
• This enclude height weight skin colour, body size,
intellectuality etc
• 20-30% variations occurs from environment in human
beings

44. Hugo De vries’ Mutation theory
• Gene control phenotype of an organism.
• During sexual reproduction gene arrange themselves in
correct order
• But sometime there occurs duplication, deletation, and
replacement of gene.
• The changes gene cause unexpected variations like growth
of six finger, more than four legs in cattle, fused head etc
• This is called a mutation.
• A mutation is a sudden permanent change in genes that
alters the genotype or phenotype of an organisms.

45. Causes of mutation
• Radiation like X-rays, UV rays Gamma-rays, etc.
• Accidental deletion, duplication or dislocation of gene
during cell division.
• Certain chemicals.

46. Difference between variation and mutation
Variation Mutation
variations occurs in
all organisms
Mutation occurs in a
certain generation.
Variation brings out
usual changes
Mutation brings out
unusual or sudden
changes.
Variation caused due
to genetic and
environmental factors.
The mutation is cause
by radiation chemical
or accidentally change
in gene sequence.

47. Significance of mutation theory
• Raw material for evolution
• It is completely different from normal species.
• The same type of mutation can appear in several
individuals or species.
• Accumulation of variation produces new species.
• Useful mutation is selected by nature.
• Mutation are inheritable.

48. Criticism of Hugo De Vries’ mutation theory
• Mutation theory cannot single-handedly explain
evolution.
• it acts as evidence for other theories
• Most mutation are recessive.
• Mutation occurs in any random possible
direction.

49. Effect of mutation on evolution
• Mutation is one of the causes of evolution
• Mutation are either harmful or useful for the
organism,
• Some are neutral

50. • Name the branch of science that studies fossils.
• Paleontology
• What are the organs that are similar in anatomy and
different in function called?
• Homologous organs
• What are the organs that have lost their function during
evolution but are present in the body called ?
• Vestigial organ.
• For what is hugo de vries famous ?
• Mutation theory

51. • In which cell does blastogenic variation take place?
• Germ cells(sex cells)
• What is an example of a bridge animal?
• Archeopteryx , dog-billed platypus.
• Name any two biologist who propounded the theory of
organic evolution.
• Charles Darwin , Lemark , Hugo de vries.

52. Define the following terms.
• Organic evolution - gradual change of living beings from simple to
complex form.
• Fossils - the preserved remains of living organisms on sediments
rock is called fossils.
• Vestigial organs - the organs that have lost their function during
evolution but are present in the body is called vestigial organs.
• Darwinism- Darwinism a theory of biological evolution developed
by the English naturalist Charles Darwin.

53. • Bridge animals- the animals which possesses the
characteristics of two groups of animal.
• Natural selection- Natural selection is the process
by which organisms with advantageous traits are
more likely to survive, reproduce.

54. List difference between following
• Mutation and variation
Variation Mutation
variations occurs in
all organisms
Mutation occurs in a
certain generation.
Variation brings out
usual changes
Mutation brings out
unusual or sudden
changes.
Variation caused due
to genetic and
environmental factors.
The mutation is cause
by radiation chemical
or accidentally change
in gene sequence.

55. Homologous and analogous organ
Homologous organ Analogous organs
They have similar basic
structure and embryonic origin
They quite different in
fundamental structure and origin.
They perform different
functions.
They perform the same function.

56. Somatogenic variation and blastogenic
variation
Somatogenic variation Blastogenic variation
They occur only I
somatic cells of an
individual.
They occur in germinal
cell of reproductive
organ
These acquired during
lifespan
These occur at the time
of formation of gamates

57. Give reason
• Horse and human are considered to have developed from the
same ancestors.
• Both are mammal and having similar anatomy of body
structure that’s why horse and human are concidered to
have developed from the same ancestor.
• Mutation only is not the factor for the evolution of the
organism.
• Mutation is not only sole factor of evolution.evolution is
complex process by multiple mechanisms such as natural
selection,genetic recombination flow of gene etc.

58. • The number of flies is not higher in spite of their rate of
reproduction.
• Files compete themselves for food nature habitat and sex
during this some flies died due to this the number of flies is
not higher in spite of their rate of reproduction
• Fossils are considered an important source for
understanding evolution
• Fossil evidence provides a record of how creatures evolved
and how this process can be represented by a 'tree of life',
showing that all species are related to each other.

59. • Variations occurs in an organisms.
• Mutations, the changes in the sequences of genes in
DNA, effect of environment all happens in organisms due to
this variation occurs an organisms.
The human forelimbs and fore limbs of a horse are called
homologous organ.
The human forelimbs and fore limbs of a horse are called
homologous organ because both forelims are similar in
anatomy and different in function.

60. • The duck-billed platypus is called a bridge animal.
• Duck-billed platypus have many characteristics of two or
more than two groups.
• Canine teeth of human beings are called vestial organs.
• Human canine teeth lost their function during time of
evolution.so it is called vestigial organs.
• Archeopteryx is considered as the animal developed into a
bird from a reptile.
• It has wings, a beak, the particular structure of legs just like
the birds, and on the other hand, it has reptile-like teeth and
a tail. It also has reptile-like skin. So, you can say that it has
evolved from a reptile to a birds.

61. • List any two pieces of evidence of organic evolution.
Evidence from the study of fossils
Evidence from comparative morphology and anatomy
Embryological evidence
Evidence from the study of vestigial organs
Evidence from the bridge organisms or connecting links
• How embryonic evidence show evolution?
• Embryos of different species can have similarities that are not
visible when the organisms are fully formed. Many of these
similarities are homologous features. These features provide
evidence that the species are related through evolution

62. • Why is the theory of Darwin criticised? list any two reason
• Darwinism explained the survival of the fittest but not the
arrival of the fittest.
• Natural selection did not explain the evolution of terrestrial
animals from aquatic forms.
• It did not explain the effect of use and disuse of organs and
the presence of vestigial organs

63. • Explain how vestigial organs support evolution.
• s. They support evolution because they suggest that an
organism changed from using the structure to not using the
structure, or using it for a different purpose.
• Describe the role of fossils for understanding evolution.
• Fossils provide important evidence for evolution and the
adaptation of plants and animals to their environments.

64. • What is struggle for existence? describe it based on
Darwinism
• competition (as for food, space, or light) of members of a
natural population that tends to eliminate weaker or less
efficient individuals and thereby to increase the chance of
the stronger or more efficient individuals to pass on their
traits.
• List types of variation based on their effects.
• Genetic variation
• Environmental variation.

65. • What kinds of mutation support evolution?explain with
example.
• Beneficial mutation which can transfer from one generation to
another generation that can help the evolution.

66. • List the four major features of hugo de vries theory of
mutation
• Raw material for evolution
• It is completely different from normal species.
• The same type of mutation can appear in several individuals
or species.
• Accumulation of variation produces new species.
• Useful mutation is selected by nature.
• Mutation are inheritable

67. • Why hugo de vries theory of mutation been criticized?
• Mutation theory has been criticized due to following reason.
• The rate of mutation is very low
• Most mutations are harmful.
• Mutations are generally recessive
• Mutation theory does not explain the role of natural
selection

68. • Draw the chart showning the evolution of human from apes

69. • How does evidence obtained from the study of embryos
support the theory of organic evolution? Describe in brief.
• mbryos of different species have differences and
similarities in structures up to a certain period during
gestation. Human, pig, reptile, and bird embryos have
similar embryonic development but as they grow, they
transform into their respective species. This demonstrates
common ancestry.

70. • Despite enormous fertility rate, population of mosquitos
remain constant.describe it based on Darwin’s theory.
• Darwin explained that despite having the enormous potential
of fertility, the population of mosquito’s remains within a
limit. It is due to the struggle between the mosquitos for
food, space, and mate. Struggle eliminates the unfit
individuals.

71. • Which organs are shown in the figure? How does evidence
obtained from the study of these organs support the theory of
organic evolution describe in brief.
• Forelimbs of organisms
• Homologous organs of organisms it provide anatomical evidence of
evolution. Because organisms having similar structures but
different in function it proves that all of given organisms are
common ancestor.

72. • How did long- necked giraffe evolve? Describe based on
Darwinism.
• Long necked giraffes and short necked giraffes existed
together they compete for food long necked giraffes able to
get food but short once do not success to get food according
to this long necked giraffes evolve.

73. Distinguish between Lamarckism and Darwinism