Biology Club Bulletin

THE WONDERS OF

evolution Bulletin by Biology Club

INSIDE: Examples of evolution Evolution FAQs Creationism vs Evolution Jokes for Valentine’s Day + a bonus crossword!

TABLE OF CONTENTS 1.

Definition and explanation of evolution

2.

Example: Evolution of vertebrates

3.

Example: Evolution of peppered moths

4.

Frequently asked questions about evolution

5.

Creationism vs Evolution

6.

Applications of evolution in daily life

7.

BONUS: Test understanding with a game!

Join upcoming Biology Club Activities in March: Hands-on Mouse Dissection Workshop 2nd Bulletin—Virus and Bacteria: The Deadly Killers I M P O R TA N T R E M I N D E R : B r i n g y o u r membership card to activities to redeem PRIZES at the end of term!

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WHAT IS EVOLUTION? Evolution is definitely not an unfamiliar term to you.

You may have heard it from peers, or read it from books. Besides, the evolutionism-christianity controversy still remains one of the hottest topics nowadays since it first sparked a furore across the world in 1859. But what exactly is evolution?

By definition, biological evolution is the process by which organisms change over time as a result of changes in heritable physical or behavioral traits.

Changes that allow an organism to better adapt to its environment will help it survive and have more offspring. Evolutionary processes give rise to diversity at every level of biological organization, including the levels of species, individual organisms, and molecules.

The central idea of biological evolution is that all life 2

on Earth shares a common ancestor, just as you and your cousins share a common grandmother.

Through the process of descent with modification, the common ancestor of life on Earth gave rise to the fantastic diversity that we see documented in the fossil record and around us today. Evolution means that we're all distant cousins: humans and oak trees, hummingbirds and whales.

Evolution by natural selection is one of the best substantiated theories in the history of science, supported by evidence from a wide variety of scientific disciplines, including paleontology, geology, genetics and developmental biology.

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Source: https://www.pinterest.com/alyflaherty3/evolution/

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EXAMPLE: VERTEBRATES To demonstrate the evolution, and thus, specialization of living organisms, we may look at the evolutionary pattern of vertebrates (animals with backbone), the very subphylum in which we, human beings, belong to.

When scientists describe vertebrate evolution, they most often frame it as a transition from water to land.

Once on land, the vertebrates are described as evolving to occupy diverse habitats and live very active lifestyles. The most distinctive adaptations that made these transitions possible, interestingly, are usually what differentiates the 5 classes of vertebrates: Fish, Amphibian, Reptile, Bird and Mammal.

1. JAWS: The earliest vertebrates in evolutionary history are the fish. The earliest fish, such as hagfish 5

and lampreys, had no jaws — they sucked and rasped flesh of their prey rather than biting it. Fish that arose later, including the sharks and the bony fish, have jaws. Jaws represent a much more efficient and effective mode of capturing, feeding on, and swallowing prey. Such advantage of jaw enables the latter fish evolves into more efficient predator.

2. LUNGS AND LIMBS: In order for vertebrates to succeed on land, they had to be able to breathe and move around. These adaptations are first seen in a primitive group of fish, of which a living example exists — the lungfish. Although they take in oxygen primarily through gills, they also have lungs. Their fleshy fins are supported by bone, and they can walk around in their habitats. The amphibians are thought to have evolved from fish like this. As their name implies – “amphibian” comes from the Greek word “amphibious,” meaning “double life” – the adaptations of amphibians truly reflect mixed habitats.

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3. WATERTIGHT SKIN AND EGGS. Although amphibians can be terrestrial, they cannot live exclusively on land due to the significant water loss through their wet skins. Evolving from amphibians, the reptiles are the first vertebrate group to show the adaptation of having dry hard scales as external coverage, acting as a watertight barrier that can minimize water loss.

Reptiles also have what is called an amniote egg.

Amniote eggs contain their own water supply and are surrounded by a leathery or hard shell. Through these adaptations, the reptile’s habitats are not restricted to aquatic ones. Such flexibility encourages the divergence of reptiles’ evolution.

4. ENDOTHERMY. Birds and mammals possess an adaptation known as endothermy, which can be roughly translated to “internal temperature”. This is what we typically call “warm-bloodedness.” This occurs as body temperature is regulated internally 7

using heat supplied by the burning of food for fuel.

Endothermy permits a degree of independence from environmental conditions. Since birds and mammals are homeotherms, they have further evolved to possess diverse ways of feeding, avoiding predators, finding suitable habitats, and reproducing.

5. MAMMARY GLAND: the key reason for the evolutionary success of mammals over the other vertebrates. Not only does the nutritional and antimicrobial properties of milk highly beneficial to the offspring’s health. Moreover, the extended period of interaction between mothers and their young, necessitated by the transfer of milk, has been suggested to afford the offspring the opportunity for more learning and the eventual development of the levels of intelligence. Other than physical adaptation, intelligence is a new breakthrough for survival in nature. Although intelligence is not only limited to mammals only, it is shown by figure that the average Intelligence Quotient (IQ) of mammals is 8

significantly higher than that of other vertebrates.

The extensive advantages brought by mammary gland and lactation makes mammals more competitive.

The above adaptation trend of vertebrates, combined with the paleontological findings such as fossils, provides a strong evidence that supports the Theory of Evolution.

SUMMARY OF VERTEBRATE EVOLUTION NEW FEATURE

SUBPHYLUM

JAWS

FISH

LUNGS AND LIMBS

AMPHIBIAN

WATERTIGHT SKIN & EGGS

REPTILES

ENDOTHERMY

BIRDS

MAMMARY GLAND

MAMMALS 9

EXAMPLE: MOTHS While the ancient evolution of vertebrates stretches over 420 million years, natural selection can be more current, rapid-paced and specific. The most famous example, is “The peppered moth evolution�.

Peppered Moth is a common moth species in England and Ireland, which is normally white with black speckles across the wings. This patterning

Pictures of the peppered moth from http://butterflyconservation.org/. They blend in well against bark!

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makes it well camouflaged against lichen-covered, pale colored-tree trunks when it rests on them. There is also a naturally occurring genetic mutation which causes some moths to have almost black wings, which are not as well camouflaged on the lichen as normal 'peppered' forms. Thus, they are more likely to be eaten by birds and other predators. This means that fewer black forms survive to breed and so they are less common in the population.

In the late eighteenth century, the Industrial Revolution begun. Coal mines and factories rapidly spread across the cities in England. However, in the nineteenth century, it was noticed that the black form of the moths was more common than the pale peppered form in urban areas. Industrialization and domestic coal fires had caused sooty air pollution, killing off lichens and blackening urban tree trunks and walls. So now it was the pale moths that were more obvious to predators, while the black ones were more likely to survive and produce offspring.

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As a result, over successive generations, the black moths came to outnumber the pale forms in our towns and cities. Since moths are short-lived, this evolution by natural selection happened quickly. The first black Peppered Moth was recorded in Manchester in 1848. By 1895 98% of Peppered Moths in the city were black.

The amazing story did not stop here. In the midtwentieth century controls were introduced to reduce air pollution. As the air quality improved, tree trunks became cleaner and lichen growth increased. Once again the normal pale Peppered Moths were camouflaged and the black forms were more noticeable. Now the situation in urban areas has again become the same as in the countryside, with normal pale Peppered Moths being far more common than the black forms. This shows that natural selection has been seen to work in both directions, always favouring the moth that is best suited to the environmental conditions.

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The examples of evolution is not restricted only to these two. In fact, more and more new examples of evolution are unearthed or discovered every day.

Unfortunately, the well-known constant debate between evolution and creation still exist: Are all the known species on Earth descended from one common ancestor, or are they individually created by a God?

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Source: http://msfrancoisap.weebly.com/bio-jokes.html

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DEBATE: some FAQs Despite the fact that evolutionism is widely accepted in the scientific field, people raise questions to challenge the authenticity of this theory. Here are a few of the common ones: 1. Well, it’s still a theory, isn’t it?

A theory might not be based on concrete evidence. It is only a proposed idea with logical deduction.

However in the field of science, a theory is a widely accepted explanation of a phenomenon. It is usually considered as a fact and other theories can be proposed based on the previous ones. So scientists are still trying to find more concrete evidence to prove it real, but at the same time it is considered to be real.

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2. How can such complex organisms be formed entirely by random processes?

A single cell is already complex enough with all its organelles serving different purposes, carrying out growth and metabolic activities. Not to mention that cells can group together to form tissues, tissues form organs, organs are grouped into systems and finally make a complete organism. If all kinds of organisms that exist in this world are evolved from a single cell by chance, you can imagine the chance of the process to have happened successfully to be extremely small.

This is why some people find this unconvincing.

Instead, some people believe that there is a designer behind all these amazing creatures.

3. How can organisms produce offsprings of a different species?

For everyone of you who possess some basic knowledge about living creatures, you would know 16

that only organisms from the same species can produce fertile offsprings. Human beings give birth to human beings, bears give birth to bears, but you would never see a cat mating with a dog and give birth to a whole new kind of animal. Occasionally gametes from two plants of different species undergo fertilisation and form a new species, but it is still not fertile. This means that the living things on earth are extremely unlikely to be formed by breeding two different species.

4. Why haven’t we ever seen organisms in the middle of an evolutionary process?

These are called the transitional organisms and they are yet to be observed by human beings. Seeing a half dog half cat might be crucial in proving the theory of evolution. But no, nobody has ever witnessed something like that. All the missing links are proposed creatures but are not proven to have existed. Instead, we can clearly classify the living 17

things on earth according to their characteristics. So how did the creatures undergo evolutionary processes? Yes, living things are proven to be able to adapt to the external environment by slightly changing their body features, but changing into a completely new species of creatures seems pretty impossible.

5. How can genetic mutation be beneficial and controlled?

DNA of living things control their physical appearances and behaviours. Therefore it is said that evolution is caused by change in the DNA content.

However, genetic mutation is proved to be completely random. It is impossible to control how they modify. Moreover, mutations are mostly harmful, seldom neutral and rarely beneficial. So if evolution occurs in order to adapt to the external environment, it seems pretty unconvincing to say that genetic mutation contributes to the process.

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Creationism vs Evolution As for debates over contradictory theories, creationevolution controversy is certainly the most heated one.

Creationism is proposed by christianity.

Creationism emphasises that all living things are created by God in 7 days, in contrast to evolutionism which believes that living things are formed by evolving constantly over time.

According to the Bible, God created all living creatures “according to their kinds�. This phrased is mentioned many times in Genesis and it shows creationism emphasizes that God created different kinds of living things separately. On the other hand, evolutionism emphasizes that all kinds of living things come from a single ancestral cell. They are formed by breeding over generations instead of being 19

created the way they are.

The Bible mentioned that human beings were created

by God on the sixth day of creation “in our image, in our likeness” (Genesis 1:26). In the Bible human beings are described as “a little lower than angels, crowned with glory and honour” (Psalm 8:5). Human beings are the most precious and prestigious creatures among God’s creations. They are granted spirits, and are only slightly lower than angels, which are spiritual creations by God. However, human beings are evolved from apes, according to evolutionism. Just like other living things, we come from our common ancestor called Homo Erectus. We are simply wiser organisms compared to other species - nothing else.

Some scientists suggested that evolutionism and creationism can co-exist. Although some of the ideas contradict with the opposite theory, there are 20

still parts which can compensate each other. When Darwin proposed the theory of evolutionism, he did not mention about God. God might have played a part in his theory, just that we haven’t thought about it. On the other hand, the Bible is not a book of science. It also doesn’t mention every single detail about the creation, which leaves blanks for people to imagine and deduce. For example, it is believed that time span of “one day” during creation might not be equivalent to 24 hours.

The debate will surely go on and on in the future. We do not know when it will come to an end, but one thing we know for sure is that more scientific discoveries have to be made before drawing any conclusions.

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VALENTINE’S DAY IS COMING! ARE YOU PREPARED?

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APPLICATIONS 1. Academic applications a) Taxonomy: The classification system used nowadays classify living things based on their evolutionary relationships. It was proposed by scientist Carl Woese in 1990. The probable sequences of evolution is deduced and helps classify all kinds of organisms in the world. b) Endosymbiosis: An evolutionary theory which explains how eukaryotic cells are formed from prokaryotic cells.

Cell organelles are originally individual bacteria.

However, they became part of another cell and function as a whole, becoming a eukaryotic cell. created the way they are.

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2. Technological application a) Artificial selection Human beings have modified genes of plants and animals for many years already. Recently, it has become a vital part in genetic engineering and has become much more efficient. b) Directed evolution Scientists have learned how to “breed� molecules by modifying genes, producing enzymes and other useful substances. c) Genetic algorithms Some evolutionary principles are the basis of genetic algorithms. It has many practical applications, such as engineering, architecture and finance.

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1 A widely accepted explanation of a phenomenon; usually considered as a fact 2 Homo ____ is an ancestor of the human species 3 "Internal temperature"; warm-bloodedness 4 Christian theory suggesting God created humans 5 Advantage of Peppered Moth against lichencovered tree trunks 6 The process by which organisms change over time as a result of changes in heritable traits 7 Evolution is caused by change in _____ content.

8 A theory that explains how eukaryotic cells are formed from prokaryotic cells 25

ANSWERS 1

THEORY

2

SAPIENS

3 4

ENDOTHERMY CREATIONISM

5 6

CAMOUFLAGE EVOLUTION

7 8

DNA ENDOSYMBIOSIS

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