The five-principal group of organisms is prokaryotes, protists, fungi, plants, and animals

Biodiversity:

Biodiversity is a measure of the variety of organisms present in different ecosystems.

The term “biodiversity” has been derived from 'bio' and ‘diversity’. Formerly it was called “natural diversity”.  “Diversity” means variety within a species and among species.

Importance of biodiversity and natural ecosystem:

Plants and animals (flora and fauna) diversity depends on the climate, altitude, soil, and the presence of other species. Biodiversity is not distributed evenly on Earth. It is richer in the tropics while there are fewer species in the polar regions. In the year 2006 large number of the Earth's species were classified as endangered or threatened species.

Examples:

1. Most of the hotspots are located in the tropics and most of the established species, are forests. For example, Brazil's Atlantic Forest contains' roughly 20,000 plant species, 1350 vertebrate species, and millions of insect species about half of which occur nowhere else in the world.
2. Biodiversity found on Earth today is the result of 4 billion years of evolution. The origin of life is not well known to science, though limited evidence suggests that until 600 million years ago, all life consisted of bacteria and similar single-celled organisms.
3. Biodiversity provides food for humans. A significant proportion of drugs are derived, directly or indirectly, from biological sources.
4. A wide range of industrial materials e.g. building materials, fibers, dyes, resins, gums, adhesives, rubber, and oil are derived directly from biological resources.
5. Biodiversity plays important role in making and maintaining ecosystems.
6. It plays a part in regulating the chemistry of our atmosphere and water supply.
7. Biodiversity is directly involved in recycling nutrients and providing fertile soils.

Evolutionary tree:

Since 1960 a trend has emerged, arranging groups of organisms in an evolutionary tree, if a group includes all the descendants of the same ancestral form it is called monophyletic. Other groups are called Polyphyletic.

Classification:

Biological classification is a method by which biologists group and categorize species of organisms.

Aims of Classification:

Taxonomy:

The branch of biology that deals with classification are called taxonomy.

Systematic:

The branch which deals with classification and also traces the evolutionary history of organisms is known as systematics. The main aims of both these branches are:

1. To determine similarities and differences among organisms so that they can be studied easily.
2. To find the evolutionary relationships among organisms.

Principles of Classification/Basis of Classification:

1. Classification is based on the relationship amongst organisms and such a relationship is got through similarity in form or structure.
2. These similarities suggest that all organisms are related to one another at some point in their evolutionary histories. However, some organisms are more closely related than others. For example, sparrows are more closely related to pigeons than to insects. It means that the former two have common evolutionary histories.
3. Biologists have classified all the known organisms and subgroups based on similarities. These similarities are seen in structures, biochemistry, cytology, and genetics.
4. Modern genetics has provided another type of information to taxonomists. The genetic differences between two studied organisms can be determined and can be used for getting the idea about similarities and differences in their structures and functions.

Carolus Linnaeus (1707-1778) divided nature into three kingdoms minerals, vegetables, and animals. Linnaeus used five ranks: Class, Order, Genus, Species, and variety. Linnaeus is best known for the introduction of his method still used to formulate the scientific names of every species.

Taxonomic hierarchy:

The groups into which organisms are classified are known as taxonomic categories or taxa (singular “taxon”) and these taxa form a ladder called taxonomic hierarchy. All the organisms are divided into five kingdoms:

The base for Establishing five Kingdoms:

Based on similarities, each kingdom is further divided into smaller groups in the following way:

1. Phylum (Division: for plants and fungi):

A phylum is a group of related classes.

2. Class: A class is a group of related orders.
3. Order: A order is a group of related families.
4. Family: A family is a group of related genera.
5. Genus: A genus is a group of related species.
6. Species: A species consists of similar organisms.

Note: Each category (taxon) is more than one below it and has emergent properties. Member of its lower taxon resembles one another more than do the members of the higher taxon.

1. The fruit fly so familiar in genetic laboratories (Drosophila melanogaster)
2. Humans (Homo sapiens)
3. The Peas used by Gregor Mendel in his discovery of genetics (Pisum sativum)
4. The Mushroom (Amanita muscaria)
5. The bacterium (Escherichia coli)                                                                                                                                                                                                                                                                                                                                                                                                                                                           

   Simple Classification of Five representative Organisms
   Taxa	Fruit Fly	Human	Pea	Amanita	E. coli
   Kingdom	Animalia	Animalia	Plantae	Fungi	Monera
   Phylum	Arthropoda	Chordata	Magnoliophyte	Basidiomycota	Proteo-bacteria
   Class	Insects	Mammalia	Magnoliopsida	Homobasidiomycete	Proteobacteria
   Order	Diptera	Primates	Fabaies	Agaricales	Enterobacterial
   Family	Drosophilae	Hominidae	Fabaceae	Amanitaceae	Enterobacteriaceae
   Genus	Drosophila	Homo	Pisum	Amanita	Escherichia
   Species	D.melanogaster	H. sapiens	P. Sativa	A. muscarine	E. coli

In 1967, Robert Whittaker introduced the five-kingdom classification system. This system is based on:

1. The levels of cellular organization i.e. prokaryotic, unicellular eukaryotic, and multicellular eukaryotic.
2. The principal modes of nutrition i.e. photosynthesis, absorption, and ingestion. On this basis, organisms are classified into five kingdoms: Monera, Protista, Fungi, Plantae, and Animalia.

Species- The Basic Unit of Classification:

Species are the basic unit of classification. “A species is a group of organisms which can be interbred freely among them and produce fertile offspring but are reproductively isolated from all other such groups in nature”. Each specie possesses its own distinct structural, ecological, and behavioral characteristics.

A mule is produced through an unnatural cross between a male donkey and a female horse.

History of classification systems:

Greek Period:

The earliest known system of classification of organisms comes from the Greek philosopher Aristotle who classified all living organisms known at that time as either in the group “plants or in animals”.

Muslim Period:

In the 700’s Abu-Usman Umer Aljahiz described the characteristics of 350 species of animals in his book. He wrote a lot about the life of ants. In 1172 Ibn e Rushd (Averroes), who was a judge (Qazi) in Seville, translated and abridged Aristotle’s “De Anima (on the soul)” into Arabic. His original commentary is now lost, but its translation into Latin is available.

Modern Period:

1. An Italian Botanist Andrea ceaselpino (1519-1603) proposed the first methodical arrangement of plants. He divided plants into 15 groups called “genera”
2. An English Naturalist John ray (1627-1705) published important works on plants’ classification.
3. Augustus Quirinus previous (1652-1723; German Botanist) and piston de Tournefort (1656-1708; French Botanist) introduced the practice of naming the plants according to their genera.
4. The category of order and Tournefort introduced even more sophisticated categories of class, section, genus, and species
5. Modern classification has its roots in the work of a Swedish biologist, Carolus Linnaeus who grouped species according to similar physical characteristics.

Two Kingdom classification system:

It is the oldest system and classifies all organisms into two kingdoms i.e. Plantae and             Animalia. According to it, all organisms that can prepare food from simple inorganic materials and thus can store energy, are autotrophs and are included in Kingdom Plantae. On the other hand, the organisms that cannot synthesize their food and depend on autotrophs or others are heterotrophs and are included in the kingdom Animalia. According to this system, bacteria, fungi, and Algae were included in Kingdom Plantae.

Drawbacks of Two-Kingdom Classification system:

Some taxonomists found the system unworkable because; many unicellular organisms like Euglena have both plant-like (presence of chlorophyll) and Animal-like (Heterotrophic mode of nutrition in darkness and lack of cell wall). Characters so there should be a separate Kingdom for such organisms. This system also ignores the difference between organisms having prokaryotic and those having Eukaryotic cells.

Three-kingdom Classification System:

In 1866, Emst Hackel solved the first objection and proposed a third kingdom; Protista to accommodate Euglena-like organisms. He also bacteria in the kingdom Protista. In this system, Fungi were still included in the Kingdom Plantae.

Drawbacks of Three-kingdom Classification System:

This system didn’t clarify the difference between Prokaryotes and Eukaryotes. Some Biologists disagreed about the position of Fungi in Kingdom Plantae. Fungi resemble plants in many ways but aren’t Autotrophs. They are a special form of Heterotrophs that get their food by absorption. They do not have cellulose in their cell walls but rather possess chitin.

The Five Kingdoms:

The general characteristics of the Five kingdoms are as follows:

1. Kingdom Monera:
2. It includes Prokaryotic organisms i.e. they are made of prokaryotic cells
3. Monerans are unicellular, although some types form chains, clusters, or colonies of cells.
4. Prokaryotic cells are radically different from eukaryotic cells.
5. Most are Heterotrophic but some perform Photosynthesis because they have chlorophyll in their cytoplasm.
6. Within this Kingdom there are two vastly different kinds of organisms i.e. Archaebacteria and Eubacteria. Many biologists believe that these two groups should be considered separate Kingdoms.
7. Kingdom Protista:

It includes Eukaryotic unicellular and simple multicellular organisms. There are three main types of Protists:

1. Algae are unicellular, colonial, or sometimes simple multicellular. They resemble plant cells with cell walls and chlorophyll in chloroplasts. Simple multicellular means that they do not have multicellular sex organs and do not form embryos during their life cycles.
2. Protozoans resemble animals whose cells lack chlorophyll and cell walls.

Some Protists are like the Fungi

• Kingdom Fungi:

It includes Eukaryotic multicellular reducers for example mushrooms. Fungi are Heterotrophic organisms that are absorptive in their nutritional mode. Most Fungi are decomposers. They live on organic material, secrete digestive enzymes, and absorb small organic molecules formed by the digestion of enzymes.

• Kingdom Plantae:

It includes Eukaryotic multicellular Autotrophs. Plants are autotrophic in nutritional mode. Making their food by photosynthesis they have multicellular sex organs and form embryos during life cycles.  Mosses, Ferns, and flowering plants are included in this Kingdom.

• Kingdom Animalia:

It includes Eukaryotic multicellular consumers. Animals live mostly by ingesting food and digesting it within specialized cavities. They lack cell walls and show movements.

Note:

Biologists believe that Kingdom Protista evolved from Monera and then it gave rise to the other three Eukaryotic Kingdoms i.e. Fungi, Plantae, and Animalia.

1. Kingdom Monera includes organisms with prokaryotic cells and
2. Kingdom Protista, Fungi, Plantae, and Animalia includes organisms with Eukaryotic cells.

Status of Viruses:

Viruses are acellular i.e. they do not possess cellular organization yet show some characteristics of living. Viruses are infectious entities that contain either RNA or DNA, normally encased in a protein coat, and reproduce only in living cells, where they cause several diseases. They are not considered organisms and thus are not included in the five-kingdom classification system. Prions and viroids are also acellular particles and are not included in the five-kingdom classification system.

In 1937, E-Chatton suggested the terms, “Procariotique” to describe bacteria and “Eukariotique” to describe animal and plant cells.

Modification of the five-kingdom classification:

In 1988, Margulis and Schwartz modified the five-kingdom classification of Whittaker. They considered genetics along with cellular organization and mode of nutrition in classification. They classified the organisms into the same five kingdoms as proposed by Whittaker.

Prions:

Prions are composed of protein only and act as infectious particles in plants.

Viroids:

Viroids are composed of circular RNA only and act as infectious particles and cause diseases in certain plants.

Binomial nomenclature:

Binomial nomenclature is the method of giving scientific names to living organisms As the word "binomial" suggests, the scientific name of a species consists of two names: the first is the genus name and the second one is the name of the species Swedish biologist Carolus Linnaeus (1707-1778) first introduced and adopted the system of binomial nomenclature.

Principles of binomial nomenclature:

1. Scientific names are usually printed in italics, such as Homo sapiens. When handwritten they are underlined. it.
2. The first term (generic name) always begins with a capital letter, while the species name is never capitalized (even when derived from a proper name).
3. In scientific journals, the main entry for the scientific name is followed by the surname of the scientist who first published the classification. For example, Passer domesticus (Linnaeus, 1758).
4. When used with a common name, the scientific name usually follows in parentheses. For example, "The house sparrow (Passer domesticus) decreasing in Pakistan."
5. v. The scientific name is generally written in full when it is first used. But when several species from the same genus are being listed, it may then be abbreviated by just using an initial for the genus, for example, Canis lupus becomes lupus.
6. The abbreviation "cf." is used when the identification is not confirmed. For example, Corvus cf. splendens indicates a bird similar to the House Crow but not certainly identified as a species.
7. The genus name and specific name may come from any source whatsoever Often they are Latin words, but they may also come from Ancient Greek, from a place, from a person (preferably a naturalist), a name from a local language, etc.

Aims of binomial nomenclature:

The value of this system is due to its widespread use and the stability of its name. In binomial nomenclature, every species can be unambiguously identified with just two words. The same name can be used all over the world, in all languages, avoiding difficulties of translation.

Distinguishing characteristics of the Five kingdoms of life:

Sometimes organisms are named in honor of the research workers who describe and classified them. For Example, the Orchid tree (Mountain-Ebony) was named Bauhinia Variegata after the swiss botanists Bauhin. Bauhinia Variegata is an ornamental tree found in Southeast Asia.

In rare cases, this abbreviation form has spread to more general use for example the bacterium Escherichia coli is often referred to as E. coli.

Extinct:

A species is called extinct when there is no doubt that the last individual of that species has died.

Threatened:

A species is called threatened when it is at risk of extinction in near future. The threatened species may be:

1. Vulnerable:

Likely to become Endangered unless the circumstances improve.

1. Endangered:

At the risk of becoming extinct because few members are left.

1. Critically endangered:

At extremely high risk of becoming extinct

Plant and animal species have gone extinct in Pakistan:

Many plant and animal species have gone extinct in Pakistan. Examples of extinct animal species are Lion, Tiger, Asiatic cheetah, Indian horned Rhinoceros, Swamp deer, Indian Wild ass, Hangul, Black Buck, etc.

Impact of human beings on biodiversity:

To improve the living conditions for 600 million humans, we are imposing serious threats to the survival of much biodiversity.

1. Habitat loss and deforestation:

Habitat loss and deforestation (cutting down of trees) are important causes of species extinctions. As deforestation proceeds in tropical forests, it becomes the main cause of the mass extinction of species. All species have specific food and habitat needs.

Importance of Tropical forests:

Tropical forests are important because they harbor at least 50 percent of the world's biodiversity. Direct observations prove that these forests are declining. The original extent of tropical rain forests was 75 million square km. Now there remains about 7.5-8 million square km, so half is gone.

The closed canopy forest in the North West Frontier Province NWFP (KPK) of Pakistan is reported to be shrinking at approximately 1 % per year. More significant is the persistent spread of farmers into the forests: the killing of trees through lopping, burning, and tapping the development of small agricultural plots among the trees, and excessive grazing by domestic animals.

1. Over-hunting:

Over-hunting has been a significant cause of the extinction of hundreds of species and the endangerment of many more, such as whales, ibex, urial, Markhor (the national animal of Pakistan) etc. Commercial hunting, both legal and illegal, is the principal threat.

1. Introduction of new species:

Introduction of non-native species is an important and often overlooked cause of extinction. When new species are introduced to ecosystems the established species in that ecosystem may not survive. The new organisms may be predators, parasites, or simply aggressive species that deprive the established species of nutrients, water and light. For example, Eucalyptus plants were imported from Australia and introduced in Pakistan. These plants consume more water and have disturbed the water table (level of underground water). It harms other small plants that grow near Eucalyptus trees.

1. Domino effects:

Domino effects occur when the removal of one species (an extinction event) or the addition of one species (an invasion event) affects the entire biological system.

Domino effects are especially likely when two or more species are highly interdependent. For example, a starfish, facilitates the coexistence of many other invertebrates by eating mussels, which otherwise would harm other organisms. If starfish are eliminated from an ecosystem, mussels grow in number and prey on other animals.

1. Pollution:

Pollution from chemical contaminants certainly poses a further threat to species and ecosystems. While not commonly a cause of extinction, it harms those species whose range is extremely small.

1. Climate change:

A changing global climate (due to pollution and global warming) threatens species and ecosystems. The distribution of species (biogeography) is largely determined by climate. When changes in climate disturb the distributions of species, many species find it difficult to adjust themselves in new climates.

Deforestation:

Deforestation means cutting down of trees for the conversion of a forest to non-forest land. It is done for using the land for various purposes such as pasture, urban use etc. The destruction of significant areas of Forest has resulted in a degraded environment with reduced biodiversity.

Causes of deforestation:

1. Sometime there is slow forest degradation and sometime sudden and catastrophic clear-cutting for urban development.
2. Deforestation can be the result of the deliberate removal of forests for agriculture or urban development, or it can be a consequence of grazing animals.
3. The utilization of forest products, including timber and fuel wood, have played a key role in human societies.

Effects of deforestation:

Erosion: Deforestation affects the amount of water in the soil and the moisture in the atmosphere. When there are no trees to keep the soil in place, the soil becomes exposed for erosion.

Less protection from wind and rain:

There is less protection from wind and rain and heavy rainfall washes the soil into rivers. Washing of essential nutrients: Essential nutrients are washed out of the soil all together. Rivers become choked up with mud and silt, which can cause floods.

Silted water:

The silted water gets stored in dams and it reduces their water storage capacity and thus their lives.

Reduces the sources of rains:

Deforestation also contributes to decreased transpiration, which lessens cloud formation and less humidity. This ultimately reduces the sources of rains.

More than 260,000 people are to the world population each day, or more then 180 each minute!

The northern areas provide habitats to musk, deer, snow leopard, Astore, Markhor and Himalayan Ibex, Woolly Flying Squirrel and the brown Bear.

Following are a few examples of environmental work that has been carried out in Pakistan in order to conserve species and the associated habitats.

1. National Conservation Strategy:

   In 1980's the IUCN and the government of Pakistan formulated the National Conservation Strategy for Pakistan for the conservation of Pakistan's biodiversity.

2. UN Convention on Combating Desertification (CCD):

   This is an international treaty against damage and poverty in drylands. Pakistan signed this in 1997.

3. Himalayan Jungle Project (HJP):

   It started in 1991 in the Palas Valley, in NWFP. It aimed at protecting one of the richest areas of biodiversity in Pakistan.

4. Conservation of biodiversity of the Suleiman Range, Balochistan:

   The Suleiman Range Chilghoza Forest is the largest Chilghoza forest in the world. In 1992 the WWF-P started its conservation program.

5. Northern Areas Conservation Project:

   The northern areas of Pakistan serve as a habitat for a number of wildlife species the survival of these species is under threat. The NACP is a project of WWF-P which is successful in implementing a ban on the hunting of these species.

6. Conservation of migratory birds in Chitral, NWFP(KPK):

   Chitral lies on the migratory route of several important bird species. These birds face enormous hunting pressure. WWF-Pakistan initiated efforts to reduce the hunting pressure in 1992. The efforts proved successful vii. Conservation of Chiltan Markhor: Hazarganji National Park is located close to Quetta and is the only remaining habitat of Chiltan Markhor in the country. WWF-Pakistan developed the management plan of the park.

7. Bear-baiting in Pakistan:

   Bear-baiting is an old game in the subcontinent that came with the Britishers, WWFPakistan has been successful in imposing a ban on this illegal practice. The government of Pakistan played an active role in putting an end to this cruel sport.

It is estimated that 200,000 of one million migratory birds passing through Chitral are killed during migration.

Endangered Species in Pakistan:

Here are a few examples of endangered species in Pakistan:

Indus dolphin:

Indus Dolphin is a fresh water river mammal. According to WWF-P only 600 animals of this species are left today in the Indus river in Pakistan. The population of the species declined because of various factors, including water pollution, poaching, and destruction of habitats due to bridges and dams etc. WWF-P has started the Indus Dolphin Rescue Operation. Indus Dolphin has a long beak, round belly, very small dorsal fin and large flippers. Although, its eyes do not have lenses (that is why it is also called the “Blind Dolphin”), the dolphin still uses its eyes to differentiate between light and dark. It relies on echolocation (Sound Sensors) to find its prey in the bottom mud. In this method it emits sound and hear its echo to locate its prey. After every 30-60 secs it needs to breathe, it comes to the surface, takes in the air and swims back to the water.

Marco polo Sheep:

Marco polo sheep are scattered in Karakorum Mountain range and Hindukush. In Pakistan, they are mostly found in the Khunjerab national park and adjoining areas. The sheep have an endangered status and their numbers have been rapidly decreasing in the last two decades. WWF-P has started projects for its conservation and identification for additional sites where Marco polo sheep occurs.

Houbara Bustard:

It is a large bird (about 60cm long with 140 cm wing span). It is omnivorous and eats seeds, insects and small animals. Houbara Bustards are migratory birds that fly to Pakistan in Winter season from former soviet territory. Large number of these birds settles down for the season in Cholistan and Thar desserts. There is decline in the number of Houbara Bustards and it is and Endangered Bird in the Thar area. It is hunted by the foreigners and this bird is popular among the Arabs. Now, the Government of Pakistan allows only limited hunting. By 1975, this bird was declared an endangered species in Pakistan. The decline in its Population is not only as a result of hunting but due to the destruction of its natural habitat.

Markhor.

Chakor Partridge.