A Brief History of Natural Diversity · system have permitted remarkable breakthrough in our...

A living fossil: Gymnocrinus richeri

Chapter I

A Brief History of

Natural Diversity

How a few key persons and

discoveries have changed our

vision of life on Earth

The Diversity Of Life On Earth

2010 © Sylvain Richer de Forges. All rights reserved. 11

Our knowledge of biology and the diversity of life on Earth

has significantly improved over the past century.

This chapter intends to highlight the key elements in the

discovery of species and our understanding of the living

world.

Some key findings such as the process of natural selection;

the discovery of DNA or the Linnaeous nomenclature

system have permitted remarkable breakthrough in our

understanding of the living world.

Today, many key findings have led to entire new disciplines

of biology such as evolutionary biology, molecular biology,

behavioral biology, ecology or zoology.

Introduction Chapter I:

A Brief History of Natural Diversity

In this chapter you will learn about key historical dates and

discoveries which have led to the current understanding of

life forms on Earth.

Biology in general is a complex field. Many breakthrough

discoveries that have occurred in the past where made by

accident while investigating other aspects. It is likely that

further breakthrough will be made in a similar way.

Therefore the importance of persevering in scientific

research efforts.

The problem with scientific research is that it works on

funding basis. However, in any real fundamental research we

do not really know what it is that we are searching for,

despite that there is certainly something to be found.

Because funds are allocated on specific targets basis,

fundamental research is disappearing and at the same time

the chances of making real breakthrough discoveries.

© Sylvain Richer de Forges

Chapter I: A Brief History of Natural Diversity



I.1 Succession of Life Forms

Over Time

Life forms have evolved over time. Numerous factors have played a role in the history of the successions of life forms on Earth. Major geological eras have been identified. Many of them mark a mass species extinction event or the apparition of new life forms. The succession of life forms in the fossil record have in fact served to define geological eras (“zoic”). From fossil observations made in the geological record we know that life on Earth has existed for at least 3.5 billion years and that many successions of life forms have occurred throughout time.




Life originated on Earth between 3.5 and 4 billion

years ago.

4 billion years ago the Earth was very different than it

is today. The atmosphere contained no oxygen. It was a

mixture of nitrogen and carbon dioxide with traces of

other gases such as methane and ammonia. Under such

conditions, there were probably no life.

The earliest fossils of living organisms are dated (using

carbon isotopes) at 3.5 billion years old from Western

Australia. They resemble present day cyanobacteria

and were probably photosynthetic.

Very early on (about 3 billion years ago), life

diversified into two major domains, Bacteria and

Archea. A third domain, the Eukarya originated 1.3

billion years later.

Life has evolved overtime through a series of steps.

The steps can be very briefly summarized as follows:

- The apparition of simple cells

- Cells became more complex

- RNA then DNA developed as the support of the

genome

- Complication and differentiation of species

overtime through natural selection

This long natural history which started about 3.5

billion years ago has resulted in the incredible

diversity of life that we observe today.

However, we are only observing today a small

fraction of all the life forms that have existed on

Earth as most species have become extinct over

time through natural events and during critical

periods which have led to mass extinctions.

Many scientists agree that we are now experiencing

a new era of mass species extinction which is for

the first time in history almost entirely the result

of one single species (humans).

I.2 Ancient Life





Fossils are the preserved remains or traces of

animals, plants, and other organisms from the

remote past.

Fossils are formed when animal remains are

deposited on sedimentary substrates (e.g. mud).

Fossils range in age from the youngest at the start

of the Holocene Epoch to the oldest from

the Archaean Eon several billion years old.

Fossils vary in size from microscopic, such as single

bacterial cells only one micrometer in diameter, to

gigantic, such as dinosaurs and trees.

Most of the knowledge that we have of ancient life

that has inhabited the planet results from the

study of fossils.

I.3 (a) Fossils: an

Historical Record of

Succession of Life Forms





I.3 (b) The fossil record provides a snapshot of the types

and successions of life forms that inhabited the

planet millions of years ago throughout the

geological eras. The oldest fossils found can be

dated at 3.5 billion years old.





Buffon is considered to be one of the main precursors in

the field of natural history.

Georges- Louis Leclerc, Comte de Buffon (7 September

1707-16 April 1788) was a French naturalist,

mathematician, biologist, cosmologist and a writer. His

theories have influenced two generations of naturalists

among whom Jean-Baptiste de Lamarck and Charles

Darwin.

Buffon is mostly known for his major work which was

published in 36 volumes from 1749 to 1789. He included

all the knowledge of the time in the field of natural

sciences. In this publication, he revealed a resemblance

between man and apes and the possibility of a common

genealogy.

Buffon is also considered to be one of the precursors of

comparative anatomy.

I.4 The Field of Natural

History: George Louis

Leclerc, comte de Buffon




Carl Linnaeus (23rd May 1707- 10 Jan 1778) was a

Swedish naturalist who has set the basis for the modern

system of binomial nomenclature. He his referred to as

the father of modern Taxonomy

Linnaeus has put into place his system of binomial

nomenclature which allows referring with precision to

all species of animal and vegetal

The system is based on a combination of 2 Latin names

which comprises of:

A name for the Genus

A specific character which often relates to a

characteristic of the species.

This nomenclature system is still widely used and

accepted today by Taxonomists.

I.5 Linnaeus & the Origin

of Species Nomenclature




I.6 Naming Species

Nomenclature is very important. All species

need to have a name in order to be referred to.

The naming of species has become a very useful

and reliable process with the implementation of

the Linnaeous nomenclature.

Each species name is formed out of Latin and

has two parts: the genus name and

the species name.

For example, Homo sapiens is the name of the

human species.

Names are often derived from ancient

Greek word roots, or words from numerous

other languages. Frequently species names are

based on the surname of a person, such as a

well-regarded scientist, or are a Latinized

version of a relevant place name.





Taxonomy: Taxonomy is the science of species

classification within their evolutionary history.

Phylogenetics: Today, the alternative to the

traditional rank-based biological classification

is phylogenetic systematics, which is

postulating phylogenetic trees, rather than

focusing on taxa to delimit.

Taxonomy is based on the principle that we

need to study species in order to understand

how they have evolved overtime and how all

species are connected to one another.

I.7 (a) Taxonomy and

Phylogeny





I.7 (b)

Studying species requires to keep specimens in alcohol

so that their anatomy and key features can be

preserved, looked into and serve as reference over time

for comparison purposes.

Collections of the British Museum preserved rare specimens, some

of them from the private Charles Darwin’s collections. © Sylvain Richer de Forges




Charles Darwin (12 feb 1809-19 april 1882) was an

English naturalist who’s work on the evolution of

living species. He has revolutionized the field of

biology.

Darwin was famous by the scientific community of

his time for his field work and his researches. He

has formulated the hypothesis that all living

species have evolved over time from common

ancestors through a process referred to as natural

selection.

His theory on natural selection had to wait until

the 1930’s for it to become generally accepted as

the driving mechanisms of the evolution process.

Darwin’s scientific discovery remains the

foundation of modern biology as it explains in a

logical and unified way the diversity of life on

Earth.

I.8 (a) Natural Selection:

Charles Darwin




Alfred Russel Wallace (8 Jan 1823-7 Nov 1913) was a

naturalist, geographer, explorer, anthropologist and

a British biologist. He is the co-discoverer of the

evolution theory by natural selection along with

Charles Darwin.

Wallace is mostly known to have proposed a theory

on natural selection which has pushed Darwin to

publish his own theory. Wallace was also one of the

main evolutionary thinkers of the 19th century which

has contributed to the evolution theory mostly on

the basis of colour displays in animals.

Wallace was also considered as an expert in the field

of geographic repartition of animal species and is

referred to as the father of biogeography.

I.8 (b) Natural Selection:

Alfred Russel Wallace




The first microscope to be developed was the optical microscope,

although the original inventor is not easy to identify. An early

microscope was made in 1590 in Middelburg, Netherlands.

The greatest contribution which has led to modern day microscopes

came from Antoine van Leeuwenhoek.

Van Leeuwenhoek is mostly known for the ameliorations he made to

the microscope and is one of the precursors of modern cell biology and

microbiology. Throughout his life, he made a number of significant

observations with his home-made microscopes which he reported to the

London Royal Society.

One of his earlier observations was on moulds and bee darts. Among

others he first observed and discovered Bacteria, Spermatozoids, flow

of blood in capillaries and muscle fibres.

Many of his observations and deductions at the time where

controversial as they went against the general belief of “Spontaneous

Generation”.

=> The use of the microscope has been a revolution in significantly

broadening our vision of the natural world and our understanding of

the biodiversity of life on Earth. Species of the macro level could

now be observed.

I.9 The Rise of the Microscope




I.10 Pasteur and

Micro-Organisms

Louis Pasteur (27 December 1822-28 September 1895)

was a French scientist, chemist and physicist by

formation who then became a pioneer of microbiology.

He has achieved remarkable breakthroughs in the causes

and preventions of diseases such as puerperal fever, and

he created the first vaccine for rabies and anthrax. His

experiments supported the germ theory of disease.

He has investigated a method to stop milk and wine from

causing sickness, a process that came to be

called pasteurization. Pasteur also made many

discoveries in the field of chemistry, most notably the

molecular basis for the asymmetry of certain crystals.

=>The discoveries of Pasteur further enhanced our

understanding and discovery of how bio-diverse the micro

world is but also how the observation of nature can lead

to remarkable breakthroughs and applications that can

benefit humans, a field now referred to as biomimetics.




The commercial value of biodiversity came apparent

during the period of great explorations.

The commerce of exotic spices as well as the trade of

exotic animals where major commerce trades at the time

(and still remain).

During that time it became rapidly apparent that trading

species would play a major part of the world economy.

This is still valid today, the trade of species account for

one of the largest economical trades worldwide.

=> At the time, the amount of trade was manageable.

However, as the trade expended (beyond spices) and the

world population grew, the trade of species is today a

major drive of species extinction as these exploitations

go much beyond the populations regeneration rates.

I.11 Spice Trade and the

Commercial Value of

Biodiversity




During the 19th century, the quest for

exploration and knowledge of the

natural world through observations

and field studies has led to numerous

breakthroughs in our understanding

of nature.

Field studies remain of crucial

importance and should not be

replaced by other disciplines.

I.12 (a) The Era of

Great Explorers




The expedition of the Challenger was the first great

oceanographic worldwide mission. It was realized

aboard the HMS Challenger between December 1872

and May 1876.

The ship travelled more than 120 000 km around

the world. The main goal of the mission was to

study marine animals and to understand the

circulation of currents.

The mission resulted in a major report. One of the

outcomes was the discovery of 4000 unknown

species of animals. The challenger expedition was a

remarkable breakthrough in the discovery of

species.

=> Such expedition model demonstrated that a lot

of knowledge can be gained at once if the resources

and efforts are allocated for this purpose.

I.12 (b) The Expedition

of the Challenger




I.12 (c) The great explorations of

the 17th and 18th century

have brought an incredible

amount of knowledge. As a

result of these explorations

we came to realize how

bio-diverse the world is.

As a consequence the world

also came to realize the

commercial benefits of

exploiting biodiversity.




Johann Gregor Mendel (22 July 1822-6 January

1884) was a monk and a Tchek Botanist. He his

renown as the father of modern genetics. Today a

law has been named after him “the Mendel Law’

that defines the way genes are being transmitted

from generation to generation.

Most of the discoveries of Mendel where made on

observations and logical deductions by studying

reproduction patterns in peas.

=> The discovery of genetic principles have led

the path to a greater understanding of evolution

and a mechanism conducting to the diversity of

life on Earth.

However a clearer understanding of genetic

principles really came with the discovery of DNA in

the 20th century.

I.13 Origins of Genetics:

Gregor Mendel




Desoxyribonucleic acid (or DNA) is a molecule present

in all living cells that contains all information

necessary for the development and function of a

given organism.

It is also the support for heredity as it is transmitted

during reproduction. DNA holds the genetic code and

constitute the genome of living organisms.

DNA was discovered by James D. Watson and Francis

Crick in 1953. By using x-ray diffraction data they

were able to propose the double helix or spiral

staircase structure of the DNA molecule.

=> The discovery of DNA led to remarkable

breakthrough in our understanding of genetics

which also provides a mechanism for the

transmission of genes and therefore the diversity of

life.

I.14 The Discovery of DNA




The expression “biological diversity” was first

introduced by Thomas Lovejoy in 1980 while the

word “biodiversity” itself was invented by

Walter G.Rosen in 1985 while preparing the

National Forum on Biological Diversity organized

by the National Research Council in 1986; the

word “biodiversity” first appeared in a

publication in 1988 when American Entomologist

E.O Wilson accounted for this forum.

Edward Osborne Wilson is a current entomologist

and biologist renown for his work on evolution

and socio-biology.

Wilson is the world expert on ants and in

particular their utilisation of pheromones as a

mean for communication. He has also studied

the massive extinctions of the 20th century and

their relations with modern society.

Edward.O.Wilson. Photo from Jim Harrison 2003

I.15 The Modern

Concept of Biodiversity




As highlighted in this first chapter, a few key

persons and great explorations have led the

way to the modern knowledge and on-going

researches to gain a better understanding of

the natural world that surrounds us.

We have come a long way since these early

days key discoveries. Despite that great

achievements have been realized, the more

we study nature, the more we come to

understand that we have only just started to

learn and exploit the potential that is within

the living environment.

Despite that many have the misconception

that we have already discovered all there is to

know, the amount of useful information still

remaining to be explored is unmatched and

virtually infinite.

Overall, it is very apparent that we still know

very little about the living environment…

Conclusion Chapter I



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