Evolutionary Genetics: Darwin's 'On the Origin of Species' Analysis

This essay provides a comprehensive overview of evolutionary genetics, primarily focusing on Charles Darwin's theory of evolution as presented in 'On the Origin of Species'. It explores the core principles of natural selection, emphasizing how heritable traits enable organisms to adapt to their environment and survive. The paper examines Darwin's observations of Galapagos finches and how their beak variations support the theory of adaptation and speciation. Additionally, it delves into the concept of survival of the fittest and genetic drift, highlighting the role of heritability in human evolution, such as the vestigial ear-wiggling feature. The essay also discusses the evolution of whales as an example of natural selection and sexual selection, as well as the controversies surrounding Darwin's theory and its importance in understanding genes and inheritance. The role of mutations and gene flow is also highlighted, providing a detailed understanding of evolutionary processes.

Running head: EVOLUTIONARY GENETICS
Evolutionary genetics. "On the origin of species by Charles Darwin
Name of the Student
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Author Note

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Introduction
Evolution is defined as a process in which the population or species change over time.
The theory of evolution by the natural selection was formulated by Charles Darwin in this
book, “On the Origin of Species” in 1859 (Aldhebiani 2018). Charles Darwin was a British
naturalist who penned this influential yet controversial book. The theory deals with the
process by which the organisms evolve or change over time as a result of the changes that is
heritable like the physical traits and behavioural traits (Aldhebiani 2018). These changes
allow organisms to better adapt to the evolving environment and help them to survive and
reproduce. Alternatively it can be stated that during the course of time, the species evolve and
all the living organisms can trace their descents to a common ancestor. Darwin in this book
also highlighted the overall mechanism of evolution through the theory of Natural Selection.
This theory deals with heritable traits that help organisms or species to survive and to
reproduce and thereby increasing the overall population (Aldhebiani 2018). The following
assignment aims to highlight the main findings of Darwin as highlighted in his book “On the
Origin of Species”. In doing so, the paper will focus on the Theory of Natural Selection,
Survival of the Fittest and genetic drift. At the end, the paper will focus on certain
controversies associated with the Darwin’s theory of evolution and other importance of
Darwin’s theory in showing light towards the concept of gene, its inheritance pattern and
heritability of traits.
Galapagos Finches and Darwin theory
During the course of his survey expedition in South America, Southern trip of Africa
and Australia, Darwin got an opportunity to study local flora and fauna. Over the course of
his expedition, Darwin began to notice intriguing patterns in the distribution and the overall
features of the organisms like finches in the Galapagos islands, in the cost of Ecuador (Grant
and Grant, 2011). Darwin notices that islands in the vicinity of Ecuador had similar yet non-
identical finches. For example, finches that feed on large seeds, tend to have large yet tough
beak. On the other hand, finches those feed on insects have sharp yet pointed beaks. Darwin
also noticed that the Finches that are found in the Galapagos islands are similar to the species
of finches located t the out-skirts of Ecuador in comparison to the finches residing in the
other parts of the world (Grant and Grant, 2011). This change is size or the structure of the
beak depending on the nature o the food is explained by Darwin by the theory of adaptation

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and this lead to the evolution of the species and speciation further. This observation of the
changing beak size of the Galapagos finches and the concept of adaptation, leads to the
foundation of the Darwin’s book, On the Origin of Species (Grant and Grant, 2011).
Darwin Theory of Natural Selection
Darwin’s theory of Natural selection was proposed in order to explain the mechanism
of evolution. The theory helped in explaining the how the population evolved or undergoes
decent modification and thereby becoming suitable for the environment. Darwin’s concept of
natural selection was based on numerous keys that are based on several observations. The
first observation stated that traits are often heritable (Wright, 2014). Heritability is the
measure of how well the difference in the individuals’ gene account for the differences in
their traits. The second observation of Darwin the theory of Natural Selection include as more
off-springs are produced, in comparison to the capacity of the environment, there occurs
survival of the fittest. The third observation include, the off springs vary in their degree of
heritable traits (colour, size and shape) (Wright, 2014). The differing body size, beak size and
the nature of the feathers of the Galapagos finches are an example of the varying degree of
heritability and thus helping to bring diversity in the species of Galapagos finches. Origin of
whales as explained by Darwin in his theory of Natural selection further helps in the
understanding of the heritability of the genes and how it help in the process of evolution and
speciation (Wright, 2014).
Heritability and Evolution in Humans
Heritability as indicted by Darwin in his first observation is measured from the range
of zero to one. Heritability that is closed to zero, highlights that difference and variation in
traits among the individual is due to the environmental factors and have little influence of
genetic differences (Richards, 2016). Characteristics like different language spoken, religion
and political preferences have zero heritability and they do not have genetic control.
Heritability factor close to one indicates that all variability in the trait comes from the genetic
differences and has negligible contribution of the environmental factors (U.S National
Library of Medicine 2020). The evolution of ear in Homo sapiens is an example of
heritability that leads to the process of adaptations. Mammals like dogs, cats and horse and
swivel their ears towards the direction of the sound. Group of muscles known as auriculares
helps in promotion of ear muscle movements (Richards, 2016). This group mainly include

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auricularis anterior which help in the upward and forward movements of ear where as
auricularis superior help in downward and backward movement of ear. In humans, wiggling
of ear is regarded as a vestigial feature. This signifies that this feature (moving of ear) was
prevalent in the ancestor of human (Richards, 2016). During, the Stone age, the ancestors of
man used to participate in hunting and thus were required to wiggle their ears towards the
direction of the sound. With gradual evolution, the hunting habits in the human ancestors
reduced gradually and thus flexibility of the ear muscle reduced and gene responsible for the
movements of ear muscles became inactive. This inactive gene failed to get transmitted into
the new lineage (Richards, 2016). This lack of inheritance of the inactive gene during the
process of evolution decreases the capability of the humans to swivel their ears. Thus
providing an example of how heritably helps in the promotion of evolution abased on
adaptation to the changing environment. Based on these simple observations, Darwin
concluded that inside a vast group of population, some of the individuals will express
heritable traits that will help them to survive and reproduce. The off-springs who have
expressed helpful traits will survive and will produce more off-spring in order to carry
forward the legacy. Darwin also concluded that since the helpful traits are heritable, and since
organisms with helpful trait will leave more off-spring these traits tend to become common or
are expressed in the large fractions in the next generation. These helpful traits further help to
being the process of speciation and at the same time, help them to adapt with the changing
environment (Richards, 2016).
Evolution of whales
The theory of evolution under Natural selection was also highlighted by Charles
Darwin in his book, “On the origin of Species”. This theory is further defined as Survival of
fittest. Darwin’s explanation of the theory of evolution through natural selection can further
be explained by the origin of whales. Darwin stated that how the process of natural selection
helps in the transformation of land mammal into whale (Tarizzo, 2012). The transition of
early whales from land to the water bodies mainly occurred through a series of steps that are
predictable (Tarizzo, 2012). Random genetic change like genetic drift and genetic shift
resulted in placing of the nostrils at the further back on the head of land whale. These genetic
drift and shift resulted in increase in the aquatic adaptations in whales as they are now not
required to surface their head to breathe in water. This was followed by more genetic drift
and genetic shift and this result in the evolution of the new species known as water whale

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(Tarizzo, 2012). Whale is thus a mammal, in-spite of having an active marine life are not
amphibians or fish. Apart from nose, evolution followed by genetic inheritance also occurred
in other parts of the body like front legs transforming into flippers and disappearance of back
legs and this was followed by streamlining of the body and development of tail flukes in
order to move swiftly through water (Tarizzo, 2012).
Natural selection in attracting mates
Darwin also described a form of Natural selection that mainly depends on the success
of the organism in attracting mate. This process is defined as sexual selection. The plumage
of the colourful peacock and male deer’s antlers are example of two characteristics that have
evolved during the process of natural selection (McGrath, 2011). Darwin however has no
significant knowledge about genes and its heritability. He only observed the overall pattern of
evolution and failed to highlight the mechanism underlying the same. This was later
explained with the discovery of genes. The physical and the behavioural changes that
promotes the process of natural selection mainly occurs at the DNA level or at the gene level.
Such changes at the gene or the DNA level are known as mutation (McGrath, 2011).
Mutations that are caused through random errors during DNA replication or DNA repair or
through radiation or certain chemical change might also help in bringing evolution (McGrath,
2011). Though mutations are random, the selection of the mutations that would survive in this
world is not random and this further highlights the survival of fittest. However, natural
selection is not the sole mechanism through which organisms evolve. The process of transfer
of genes can also occur through immigrations and this process is known as gene flow or flow
of the gene (McGrath, 2011).
Survival of the fittest
The phrase, survival of the fittest has originated from the Darwinian evolutionary
theory. It was an approach introduced in order to describe the process of natural selection. In
evolutionary biology, the concept of fitness is defined as a process of attaining reproductive
success (Richards, 2016). Under the light of Darwin’s explanation, it can be stated that
survival of the fittest mainly signifies that copies of gene that will pass on successfully to the
new generation are fit genes and thus they are helping to carry forward the lineages. Darwin
borrowed the term survival of fittest from the English Sociologist and philosopher Herbert
Spencer who first coined this phrase in this book name Principles of Biology (Richards,

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2016). Darwin however, did not considered the process of evolution as the survival of the
fittest. Darwin on the other hand, regarded it as the survival of the fitter under the light of the
struggle for existence. The phrase struggle for existence was first coined by the English
economist and demographer named Thomas Malthus. Darwin’s theory of evolution by
natural selection mainly highlighted three vital elements namely: variation, reproduction and
heritability. Variations in the physical features within the species help in bringing diversity
with the species. Moreover, an organism who has diverse gene or trait combination are more
likely to adapt efficiently under the changing environmental condition and thus helping to
survive (Richards, 2016). Thus one who is having variance in the genes or is flexible to
adaptation in the changing environment is considered to be fittest or fitter. Second element
includes reproduction. In order to carry forward the concept of speciation and diversity, it is
important to reproduce and fittest organisms will reproduce healthy off-spring and
inheritance of the healthy gene will help to carry forward the fit organism or species. Some of
the scientists and philosopher have highlighted that notion of the survival of the fittest as an
example of the circular reasoning and this popularly known as tautology (Richards, 2016).
The term tautology signifies that statements are framed in such a way that it cannot be
considered false without the presence of inconsistency. Darwin also noted that individuals did
not start with identical or same set of characteristics. Thus the forces affecting the survival
did not weight on the individuals and the other species equally. There are always certain ways
of variations and some of which might prove to be favourable and at the same time confer
overall fitness quotient over others and this justifying the survival of the fittest. Bouchard
(2011) stated that fitness occupies an important place in the conventional explanation of the
concept of Darwinism. The survivals of the fitter individuals will help in carrying forward a
healthy lineage in the long run (Richards, 2016).
Genetic Drift and underlying inheritance behind evolution
Genetic drift is defined as change in allele frequencies in a defined population from
one generation to the next and this occurs mainly due to chance events. Alternatively, it can
be said that genetic drift is a change that occur due to sample error in the selection of the
alleles for the next generation from the pool of genes present in the current generation. The
overall process of genetic drift is higher among the small population. The concept of genetic
drift helps in explaining the third principle of the Darwin’s process of Natural Selection and
this include : off springs vary in their degree of heritable traits (Masel, 2011).

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Bottle neck is an example of when the process of genetic drift occurs over the
population of extremely small size. Natural calamities like flood forest fire, drought can
decimate a population, killing majority of the species and thus leaving behind a random
assortment of the lucky survivors. The small population size thus, has differing allele
frequencies in comparison to the initial population along with the missing of few alleles. The
small population size is vulnerable to effects of genetic drift from generations and thus
resulting in the loss of further alleles. Genetic bottle neck is responsible for the reduction of
the genetic diversity (Masel, 2011).
Genetic Drift and Natural selection of Darwin’s finches
Abzhanov (2010) stated that one of the classic examples underlying the adaptive
radiation under the natural selection include evolution of the closely associated species of
Darwin finches (Passeriformes). Their primary diversity is reflected in the size and shape of
the beak. The study conducted by Petren et al. (2010) was first to highlight the genetic
analysis of specimens that are collected by Darwin. The authors mainly used genetic tools
like coning and DNA sequencing and multi-locus microsatellite markers in order extract the
genotype of both modern and historical finches at Galapagos. The aim of Patren et al. (2010)
was to investigate the loss of diversity and the study showed significant evidences behind the
loss of diversity of the Galapagos finches but none of the fiches have gone extinct. The
change in the genetic diversity among these finches was highlighted as the main reason
behind the loss of diversity.
Grant and Grant (2003) stated that Darwin’s finches present in the Galapagos Islands
are extremely compatible for raising several evolutionary questions associated to adaptation
and overall multiplication of species. A total of 14 species under the umbrella of Darwin
finches are related closely genetically as they are derived from the common ancestors, nearly
2-3 million years ago. They resides in the environment under which they evolved and none of
the species that are being identified by Darwin have extinct due to human invasion. The
principal factors underlying the evolutionary diversification include environmental change,
the process of natural selection and cultural evolution. Evolution mainly occurs by the
process of natural selection as proposed by Darwin and evolution in finches occurred during
the change in the food supply as a result of droughts. Change in the environment also resulted
in genetic drift resulting the evolution of species (Grant & Grant, 2003).

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Obstacles of Darwin’s theory
Darwin’s theory of evolution explained under the light of the natural selection is
regarded as central to the modern biology. However, it is refuted by numerous researchers.
Cognitive obstacles towards accepting evolution by the process of natural selection mainly
encompass conceptual difficulties and other methodological complications along with the
coherence of the problems that are being derived through intuitiveness of the alternative
theories. The prime emotional hurdle towards accepting the Darwin’s theory of evolution and
natural selection include apparent conflict with the valued belief about God, morality and
souls (Thagard and Findlay 2010).
Concept of evolution over psychology
Darwin has himself highlighted the role of cognitive evolution for the evolution of the
mind of an individual during a series of ages. This also helps in the promotion of the mental
adaptation during the changing needs of evolutionary era. Darwin also suggested that the like
any other human characteristics, the mental health or mental thought process are an outcome
of the evolution through sexual and natural selection. Darwin also insisted that these should
be understood under the light of common descent. Darwin mainly highlighted the
evolutionary interpretation of human cognition (Bolhuis et al., 2011).
Conclusion
Thus from the above discussion, it can be concluded that the Darwin's book "On the
Origin of Species" published in the year 1859 helped to open a new gate in the path of the
evolutionary biology. Darwin first identified the concept of evolution from his observation
while he was undertaken expedition in the coasts of South Africa, Australia and South
America. Observation of the Galapagos finches helped him first identify the concept of
evolution. This helped in coining of the Theory of Natural Selection and Survival of the
Fittest. This also helped in the later identification of the genetic drift. The overall concept of
Darwin's theory of evolution is,
In order to get accustomed with the changing environmental condition, the organisms
or different species undergoes certain degree of adaptations like formation of strong beak in
order to feed on hard fruits lead to the development of new traits and this new traits is then
pass on to the new generation and resulting in the process of evolution. The fitter organisms
who can easily adapt with the changing environment are successful to carry forward their

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lineage (reproduction) in the next generation. Darwin's theory of evolutionary biology, is
also applicable under the domain of the evolutionary psychology. The changing the
dimension of the cognition and thought process further helps to adapt mentally to the new
surrounding environment.

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References
Abzhanov, A. (2010). Darwin's Galapagos finches in modern biology. US National Library
of Medicines: Philosophical Transactions B.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2830240/
Aldhebiani, A.Y., (2018). Species concept and speciation. Saudi journal of biological
sciences, 25(3), pp.437-440.
Bolhuis, J. J., Brown, G. R., Richardson, R. C., & Laland, K. N. (2011). Darwin in mind:
New opportunities for evolutionary psychology. PLoS biology, 9(7).
Bouchard, F., 2011. Darwinism without populations: a more inclusive understanding of the
“Survival of the Fittest”. Studies in History and Philosophy of Science Part C: Studies
in History and Philosophy of Biological and Biomedical Sciences, 42(1), pp.106-114.
Grant, P.R. & Grant, B.R., (2011). How and why species multiply: the radiation of Darwin's
finches. Princeton University Press.
Grant, R.B. & Grant, P.R., (2003). What Darwin's finches can teach us about the evolutionary
origin and regulation of biodiversity. BioScience, 53(10), pp.965-975.
Masel, J., 2011. Genetic drift. Current Biology, 21(20), pp.R837-R838.
McGrath, A. E. (2011). Darwinism and the divine: evolutionary thought and natural
theology. John Wiley & Sons.
Petren K., Grant P. R., Grant R. B., Clack A. A.,& Lescano N. V.(2010). Multilocus
genotypes from Charles Darwin's finches: biodiversity lost since the voyage of
the Beagle. Phil. Trans. R. Soc. B 365, 1009–1018
Richards, R.J., (2016). Darwin’s theory of natural selection and its moral purpose. Debates in
Nineteenth-Century European Philosophy: Essential Readings and Contemporary
Responses, pp.211-225.
Tarizzo, D. (2012). Speculative Evolution: Darwin, Freud, and the Whale. The Yearbook of
Comparative Literature, 58(58), 71-94.

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Thagard, P. and Findlay, S., 2010. Getting to Darwin: Obstacles to accepting evolution by
natural selection. Science & Education, 19(6-8), pp.625-636.
U.S National Library of Medicine. (2020). What is heritability.Access date: 3rd April 2020.
Retrieved from: https://ghr.nlm.nih.gov/primer/inheritance/heritability
Wright, S., (2014). The genetical theory of natural selection. Essential Readings in
Evolutionary Biology, p.73.