Evolutionary Biologists and their contribution to the field of Science

1. Evolutionary Biologists and their
contribution to the field or
Evolution
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2. The Tree of Life
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• All living things share a common
ancestor.
• We can draw a Tree of Life to
show how every species is related.
• Evolution is the process by which
one species gives rise to another
and the Tree of Life grows

3. Evolution as Theory and Fact
Rodin’s “The Thinker”
• Confusion sometimes arises as to
whether Evolution is a theory or a fact.
Actually it is both!
• The theory of Evolution deals with how
Evolution happens. Our understanding
of this process is always changing.
• Evolution is also a fact as there is a
huge amount of indisputable evidence
for its occurrence.
Evolutionary processes give rise to diversity at
every level of Biological organization including
species, Individual organism and molecules such as
DNA and proteins

4. Charles Robert Darwin
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Voyage of the Beagle
• Naturalist Charles Robert Darwin was
born on February 12, 1809, in the tiny
merchant town of Shrewsbury,
England.
•He was the second youngest of six
children. Darwin came from a long line
of scientists. His father, Dr. R.W.
Darwin, was as a medical doctor, and his
grandfather, Dr. Erasmus Darwin, was a
renowned botanist.
•Darwin’s mother, Susanna, died when
he was only 8 years old. Darwin was a
child of wealth and privilege who loved
to explore nature.
•From 1831-1836, a young naturalist
called Charles Darwin toured the world
in HMS Beagle.
•

5. • English Naturalist
• Traveled Around The World On The Beagle – Famous In The Galapagos
Islands
• Observed Many Species And Fossils
• Why Did Some Species Survive While Others Became Extinct?
• He introduced the concept of Natural Selection
• The primary mechanism for evolution is natural selection.
• He established all species of life have descended over from common ancestor
and proposed the scientific theory that branching pattern of evolution.
• The struggle for existence has a similar effect to the artificial selection
involved in selective breeding
• Darwin’s Galapagos
finches are an example of this
process in action

6. • The main (but not only) driving force for evolutionary change is natural
selection, the survival of certain traits because they better adapt the
organism for its survival.
• Natural selection doesn’t just select against inferior organisms, it selects for
superior organisms and leads to even more superior organisms.
• Darwin continued working and writing the rest of his life (22 more years).
Many ideas that were omitted from On the Origin of Species (such as the
animal ancestry of humans) or only briefly mentioned (such as sexual
selection and the expression of the emotions) became the subject of other
books. Darwin’s Origin of Species released November 22, 1859
• Darwin received several scientific awards, but was never knighted. When
he died in April 1882, however, he was buried in Westminster Abbey in
London.

7. Alfred Russel Wallace (1823-1913)
• He was a British naturalist, explorer,
geographer, anthropologist, and biologist
• He is best known for independently
conceiving the theory
of evolution through natural selection.
• Wallace did extensive fieldwork, first in
the Amazon River basin and then in
the Malay Archipelago.
• where he identified the faunal divide now
termed the Wallace Line, which separates
the Indonesian archipelago into two distinct
parts
• A western portion in which the animals are
largely of Asian origin, and an eastern
portion where the fauna reflect Australasia.

8. • Wallace was one of the leading evolutionary thinkers of the 19th century
sometimes called "father of biogeography“
• He made many other contributions to the development of evolutionary
theory besides being co-discoverer of natural selection.
• These included the concept of warning colouration in animals, and
the Wallace effect, a hypothesis on how natural selection could
contribute to speciation by encouraging the development of barriers
against hybridization.
• His interest in natural history resulted in his being one of the first
prominent scientists to raise concerns over the environmental impact of
human activity.

9. Jean Baptiste LAMARCK
(1744 – 1829)
• Lamarck rejected fixity
• He proposed a theory of evolution
which is attractive but it was
eventually rejected because of the
way inheritance works.
• Lamarck noticed that organisms
adapted to a particular niche had
well developed specialised organs
• For example a carnivore will have
long canine teeth to grip its prey

10. • He proposed The Law of Use and Disuse and The Inheritance of Acquired
Characteristics. The classic example given is that of the giraffe’s neck
• Lamarck vs. Darwin
• Lamarck’s theory required adaptation to create new variations
• This was followed by the inheritance of these characteristics
• Darwin’s theory requires random hereditary variation first, followed by
selection of the variations
• The argument was over when Mendel’s laws of genetics were rediscovered at
the end of the 19th century
• Variations are due to hereditary traits passing from one generation to the next
in predictable frequencies
• Lamarckism in evolution theory today
• Some behaviour patterns are innate and will also evolve in by natural
selection
• learned behaviour patterns can be changed within a generation
• The evolution of learnt behaviour is much faster than genetic evolution and it
plays an important role in human cultural evolution

11. Gregor John Mendel (1822-1884)
• Responsible for the Laws governing
Inheritance of Traits
 Mendel was an Austrian monk and Biologist whose
work on heredity become basis of “The Modern
Theory of Genetics”
Studied the inheritance of traits in pea plants
Developed the laws of inheritance
Mendel's work was not recognized until the turn of the
20th century
Between 1856 and 1863, Mendel cultivated and tested
some 28,000 pea plants
He found that the plants' offspring retained traits of
the parents
Called the “Father of Genetics

12. • Mendel produced Hybrid strain of bees, which produce
excellent Honey
• In 1900 Mendel's work was recognized by three independent
investigators
• Hugo de Vries, Carl Correns and Erich von Tschermak
• Research in Population Genetics
• This experiments to make led him two generations the law of
segregation and law of independent assortment becomes
Mendel law of inheritance.

13. Barbara McClintock (1902-1992)
• Barbara McClintock (June 16, 1902 –
September 2, 1992) was an American
scientist and cytogeneticist who was
awarded the 1983 Nobel Prize in
Physiology or Medicine.
• There she started her career as the leader
in the development
of maize cytogenetics, the focus of her
research for the rest of her life.
• From the late 1920s, McClintock
studied chromosomes and how they
change during reproduction in maize.

14. • One of those ideas was the notion of genetic recombination by crossing-
over during meiosis-a mechanism by which chromosomes exchange
information.
• She produced the first genetic map for maize, linking regions of the
chromosome to physical traits
• She demonstrated the role of the telomere and centromere, regions of the
chromosome that are important in the conservation of genetic information.
• During the 1940s and 1950s, McClintock discovered transposition.
• She developed theories to explain the suppression and expression of
genetic information from one generation of maize plants to the next.
• Later, she made an extensive study of the cytogenetics and ethnobotany of
maize races from South America.
• Awards and recognition for her contributions to the field followed, including
the Nobel Prize in Physiology or Medicine, awarded to her in 1983 for the
discovery of genetic transposition; she is the only woman to receive an
unshared Nobel Prize in that category.

15. Sir Ronald Aylmer Fisher (1890-1962)
• Born: East Finchley in London
• Died: 29 July 1962
• Nationality: British
• Fields: Statistics, Evolutionary Biology,
Genetics.
• He was a British statistician and biologist who
used mathematics to combine Mendelian
genetics and natural selection.
• He established his reputation there in the
following years as a biostatistician.
• He is known as one of the three principal
founders of population genetics.

16. • He outlined Fisher's principle, the Fisherian
runaway and sexy son hypothesis theories of sexual
selection.
• Fisher is considered the founder of modern
genetics because of his many important
contributions to that field
• In 1992 he gave a new definition of Statistics
• He identified 3 fundamental problems:
Specification of the kind of population that the data
came from, parameter estimation, and
distributional problems.

17. Theodosius Grygorovych Dobzhansky
• Born: January 25, 1900
• Died: December 18, 1975 (aged 75)
• Fields: Evolutionary biology, genetics
• He is a Russian geneticist who moved to the
United States, provided laboratory evidence
for natural selection and variation where
previously there had been only field
observation.
• Dobzhansky's work with Drosophila, or fruit
flies, provided new evidence that
supported Darwin's theory that natural
selection, acting on genetic variation in
populations, is a driving force in evolution.

18. • In1930s that a number of scientists in different fields began to reconcile
the findings of genetics and inheritance with Darwin's theory and its
emphasis on natural selection.
• The resolution was called the “Evolutionary Synthesis" or “Modern
Synthesis," and one of its architects was Russian population geneticist.
• Later, Dobzhansky moved to the United States in 1927, and, through his
lifelong experiments with fruit flies, showed that natural populations of
the flies exhibited the same kinds of genetic variations that could be
produced artificially by mutation in the laboratory.
• His 1937 book Genetics and the Origin of Species was one of the
cornerstones of the modern synthesis.
•

19. G.H.HARDY
• Born: February 7 1877
• Died: December 1, 1947
• Residence: England
• Nationality: United Kingdom
• Field: Mathematics
• G. H. Hardy was an English
Mathematician, known for his
achievements in number theory &
Mathematical analysis.
• Starting in 1914, Hardy was the mentor
of the Indian mathematician Srinivasa
Ramanujan, a relationship that has
become celebrated.

20. • Hardy almost immediately recognised Ramanujan's extraordinary
albeit untutored brilliance, and Hardy and Ramanujan became close
collaborators.
• In an interview by Paul Erdos, when Hardy was asked what his
greatest contribution to mathematics was, Hardy unhesitatingly replied
that it was the discovery of Ramanujan
• He called their collaboration “The one romantic incident in my life“.
• Hardy also known for formulating the Hardy-Weinberg principle, a
basic principle of population genetics, independently from Weinberg in
1908.

21. Wilhelm Weinberg (1862-1937)
• Born: December 25, 1862 Stuttgart
• Died: November 27, 1937 (aged 74)
• Nationality: German
• Occupation: Obstetrician- Gynecologist
• He was a German obstetrician-gynecologist,
practicing in Stuttgart, who in a 1908 paper,
published in German.
• Much of his academic life he spent studying
genetics especially focusing on applying the
law’s of inheritance two populations
• Weinberg developed the principle of genetic
equilibrium independently of British
mathematician G.H. Hardy.

22. Julian Huxley (1887-1975)
• He was a British evolutionary biologist, eugenicist,
and internationalist.
•In the early 20th century, scientist started to
make sense of how evolution worked.
• Building on Mendel’s genetics, studies
showed how characteristics in a population
could be selected by environmental
pressures.
• This Modern Synthesis, as Julian Huxley
called it, brought Darwin’s Natural Selection
back to the centre of evolutionary theory.
en.wikipedia.org/wiki/Image:Hux-Oxon-72.jpg
Julian Huxley
and the
Modern Synthesis

23. J.B.S.HALDANE
• Born: Nov 5 1892
• Died: Dec 1, 1964
• Residence: United Kingdom, India
• Nationality: British, Indian
• Field: Biology
• As a scientist his best known contributions are in the
mathematical theory of evolution. He is one of the founders
of population genetics.
• Besides all the Sciences, He was interested in Western
Classics, Hindu philosophy, Linguistics, Economics & So on.
• Haldane major contributions to Science were in three
different fields Biology are Physiology, Genetics &
Biochemistry.
• In Cambridge he concentrated on the study of enzymes, he
calculated the rate at which enzyme reaction take place.
• His greatest contribution was in a series of ten papers on “A
Mathematical Theory Of Natural & Artificial Selection”.

24. HUGO DE VARIES
• Born: Februvary 6, 1848
• Died: May 21. 1935
• Residence: Netherland
• Field: Botany
• He was a Dutch Botanist, who independently
rediscovered the Laws of heredity developed
by the Mendel and brought the concept of
Mutation in to the Evolutionary theory.
• De Varies developed an early interest in
Botany. He received his Ph.D from the
University of Leiden in 1870, then went to the
University of Heiderberg to work with
German Plant Physiologist Julius Von Sachs.

25. • By the late 1880s De Varies had become interested in the
growing controversy surrounding plant heredity,
particularly with regard to Evolutionary theory. His
hybridisation experiments led him in 1900 to rediscover
Mendelian laws of heredity.
• He explained that the species changed over time most
likely through changes, which he called Mutation genes.
• According to him, new species arose primarily in this
manner, with no obvious transition forms.

26. SEWALL WRIGHT
• Born: December 16, 1889
• Died: March 3, 1988
• Nationality: United States
• Field: Genetics, Population genetics
• His papers on inbreeding, mating system, &
genetic drift make him a principal founder of
Theoretical population genetics, along with
R.A.Fischer and J.B.S.haldane.
• Their theoretical work is the origin of the
modern evolutionary synthesis or
Neodarwinian synthesis.
• Wright was the discovered the inbreeding
coefficient & F-Statistics, Standard tools in
population genetics

27. • He was the chief developer of the mathematical theory of
genetic drift. Which is sometimes known as Sewall Wright
effect.
• Wright was convinced that the Introduction of genetic drift &
the evolutionary forces was important in the process
adaptation.
• He did major work on the genetics of guinea pigs & many of
his students became influential in the development of
mammalian genetics

28. Birbal Sahani
• Born :14 November 1891, Bhera, Shahpur
• District: West Punjab
• Died: 1949
• Nationality: Indian
• Field:Paleobotany
• He was the third son of Ishwar Devi and Lala Ruchi
Ram Sahani who lived in Lahore.
• Birbal Sahni received his early education in India
at Govt. College University, Lahore (where his father
worked) and Punjab University (1911).
• He learnt botany under Shiv Ram Kashyap (1882-1934),
the "father of Indian bryology". He graduated from
Emmanuel College, Cambridge in 1914.
• He later studied under Albert Charles Seward, and was
awarded the D.Sc. degree of the University of London
in 1919.

29. He was also appointed as the fellow of the Royal Society of
London (FRS) in the year 1936, which is the biggest British
Scientific honor.
 Birbal Sahni was a paleobotanist and geologist of India who
studied the fossils of India sun continent.
 Sahni worked on living plants species and examining
evolutionary trends and geographical distributions.
 He recorded foreign pollen in the ovules of living Gingko
biloba and noted in the New Phytologist (1915), the problem
with assuming that fossil pollen in ovules belonged to a single
species.
He also described Glossopteris in detail and identified
differences between the flora of India and Australia with that of
China and Sumatra.

30. THANK YOU