[Biology Class Notes] on Taxonomical Aids Pdf for Exam

The living world around us, consisting of billions of microorganisms, plants, and animal species, is extremely diverse. Hence, in our quest to learn about them, it is of utmost significance that these species are sorted into groups, based on similar features to make our work a little easier. Taxonomy can be defined as a scientific process to classify and arrange living organisms into groups based on their shared characteristics. The groups into which organisms are sorted are termed as taxa and they are designated a taxonomic rank to denote a hierarchy in the taxonomic classification.

The Swedish botanist Carl Linnaeus is considered as the founder of the modern taxonomy, a system termed as Linnaean taxonomy and includes ranks of kingdom, phylum, class, order, family, genus, and species in descending order. The modern system of taxonomy and the process of sorting organisms into the same taxonomic units has greatly advanced studies of phylogenetics and systematics and even established evolutionary relationships between individual organisms or species, both living and extinct. Collections of samples from organisms or the whole organism can be preserved under appropriate conditions to help in extensive research on the living world by identification of taxonomic ranks, called taxonomical aids. Common taxonomical aids include a herbarium, botanical gardens, zoological parks, museums, keys etc.

• Herbaria: A herbarium can be defined as a collection of preserved plant specimens along with the data corresponding to that plant. The earliest account of creating herbarium has been recorded in Italy in the year 1532, where Luca Ghini, the Italian physician and botanist, along with his students, came up with the method.

 

A Herbarium Sheet

The specimens that are stored can be either the whole plant or a part of the plant, for example, leaves, flowers etc. To ensure maximum shelf life for the stored specimen, it is of extreme significance that a proper method is followed. Usually, the plant or its parts after collecting are cleaned and dried before mounting on sheets of paper. This process is termed as exsiccatae. Other methods of storage are also employed for creating a herbarium depending upon the specimen, which is being preserved, sometimes the samples are kept in boxes or preserved in alcohol or other chemicals. A collection of fungi stored in a similar manner is termed as a fungarium and a collection wood specimen is called a xylarium.

Many universities, research institutions, museums around the world maintain herbaria for storing and preserving plant specimens for aiding taxonomical studies. The Natural History Museum in England, the National Museum of Natural History in France and Harvard University in the US are known to house some of the biggest herbarium collections in the world. 

• Botanical Gardens: A botanical garden can be defined as a garden with intent to collect, cultivate, preserve, and display various plant species together with their botanical information. The garden can be dedicated towards a specific type of collection like marine plants, cacti, alpine plants, medicinal plants etc. or may house general collections sorted into groups.

Universities, educational and research institutes or governmental organizations usually run botanical gardens. In most gardens, visitors are allowed to view the collection and to access the information available. Unlike herbaria, the plants in botanic parks are preserved as live specimens to aid the study of plant taxonomy and botany. Sometimes greenhouses and shade houses are also associated with the gardens to provide the plants optimum environmental conditions that are essential for their growth. Most botanical gardens also have an in-house herbarium collection for studying. 

The idea of a modern botanical garden, for growing and preserving live plant collections, was conceived as early as in the 16th century in Renaissance Italy. However, in those ancient times, the botanical gardens only housed collections of medicinal plants. It was only in the 18th century, after the concepts of classification and nomenclature was introduced, botanical gardens were established for educational purposes. Braunschweig Botanical Garden in Germany and Royal Botanical Gardens in Kew (England) are two of the most famous botanical gardens in the world. 

• Zoological Parks: A zoological park (also called the zoo, animal park or menagerie) can be defined as a facility where live animals are housed in an area or enclosures under proper conditions and are open to visitors.

The oldest record of a modern zoological garden dates back to the 3500 BCE in Egypt. Many kings and emperors were also known to house animal facilities (both private and or public) in their kingdoms. In recent times, most zoos are designated as conservation parks or bio parks and focus on preserving animals in their natural habitats in which they can thrive instead of cages or enclosures. Zoo authority mostly encourages the animals to breed in captivity and most zoological parks house nurseries and veterinary medical facilities to provide the care the animals need for a healthy life. Some zoos also have specially made in-house water bodies, nocturnal facilities, birdhouses and temperature-sensitive enclosures, as needed. Some of the largest and most well-known zoological parks include the Bronx Zoo (United States of America), the London Zoo (established in 1826 in England, it is also the oldest zoo in the world) and the San Diego Zoo (United States of America).

 

Zoological Parks

• Museums: A museum can be described as a facility that conserves artefacts and specimens of archaeological, cultural, artistic, and scientific significance. These exhibits are used for both research purposes as well as open for public display. The museum, some of which are dedicated to natural history, houses large collections of life-sized animal models, plant specimens, various fossils, geological samples, fungi etc. They not only act as aids in taxonomic studies but also assist in evolutionary studies and paleontological and geological research. The collections are preserved with utmost care under proper storage conditions and with maximum security. Some of the most prominent natural history museums around the world including the Natural Museum of China (Beijing, China), Swedish Museum of Natural History (Stockholm, Sweden), American Museum of Natural History (New York, United States of America), National Museum of Natural History (Paris, France) etc.

• Keys: Keys (also called identification keys) are tools that help in the study of taxonomy by aiding the process of identification of plants, animals and other biological beings based on their characteristics. Keys are either printed or computer-based devices. To identify the organism, the user is required to answer a question related to the features or characters of the biological entity. The keys usually are conventionally designated as single-access, which has a particular sequence of steps for the identification process, each of those steps has two or more alternatives and based on the option chosen in a step, the next step is determined. If in a step there are two alternatives, it is termed as a dichotomous key, if the number of alternatives is more than two, the key is polytomous. In dichotomous keys, the pair of alternatives is known as a couplet and each alternate is termed as a lead. In recent times, multi-access keys have been introduced in which the users are permitted to choose the steps for the identification of their organism as well as the order of the steps. Keys can also be used in the identification of various microorganisms and fossils.

 

Importance of Classification of Living Things

There are many benefits of classifying living things. Some of them are-

• Studying all living things can be a difficult task. Classification allows one to group the animals into suitable categories based on easily observable characters. This makes it easier to understand the patterns in them.

• Classification of living things helps to investigate phylogenetic relationships between all the organisms

• With classification, it is easier to deal with newly identified organisms by putting them into particular groups. This later also assists in identifying other features of the organism.

 

Binomial Nomenclature

The method of naming organisms is called Binomial Nomenclature. Giving scientific names to the organisms helps in their classification. This helps very much when a new organism is discovered. Different names assist in observing the relationship of the species with the other organisms placed in the same genus. That is why Binomial Nomenclature is important. The rules of binomial nomenclature are as follows-

The scientific name of any organism has 2 words. The 1st word is the name of the genus and the 2nd name refers to the name of the given organism’s species.The 1st word is given to the name of the ‘genus’ and it always starts with a capital letter. The 2nd word which is the specific name always starts with a small letter. Biological names are usually in Latin and written in italics.