Diversity in the Living World: Biology

Diversity in the Living World

• Biology studies life forms and processes.
• The living world has a great diversity of organisms.
• Early humans differentiated between living and non-living things.
• They worshipped inanimate objects and organisms.
• Humans later described living organisms.
• Anthropocentric views limited biological knowledge.
• Detailed life form descriptions led to systems for identification, nomenclature, and classification.
• Studies revealed similarities among organisms, both horizontally and vertically.
• The idea that all organisms are related humbled humans.
• Cultural movements for biodiversity conservation emerged.
• The unit describes animal and plant classification from a taxonomist's view.

Ernst Mayr (1904–2004)

• Ernst Mayr, born July 5, 1904, in Kempten, Germany, was a Harvard evolutionary biologist.
• He was called "The Darwin of the 20th century" and one of the 100 greatest scientists.
• Mayr joined Harvard in 1953 and retired in 1975 as Alexander Agassiz Professor of Zoology Emeritus.
• His 80-year career covered ornithology, taxonomy, zoogeography, evolution, systematics, and the history/philosophy of biology.
• He focused evolutionary biology on the origin of species diversity.
• Mayr pioneered the current definition of a biological species.
• He won the Balzan Prize (1983), the International Prize for Biology (1994), and the Crafoord Prize (1999).
• Mayr died in 2004 at age 100.

The Living World

• The living world is amazing and diverse.
• Habitats like cold mountains, forests, oceans, lakes, deserts and hot springs evoke awe.
• Examples include a galloping horse, migrating birds, and an attacking shark.
• Ecological interactions and molecular processes prompt reflection on the nature of life.
• There are two questions withing it. The first is technical and seeks answer to what living is as opposed to the non-living, and the second is a philosophical one, and seeks answer to what the purpose of life is.

Diversity in the Living World

• There is a huge variety of living things all around.
• This includes visible organisms such as plants, insects, birds, pets, and also unseen organisms.
• Observing larger areas increases organism variety such as in dense forests.
• Each unique organism represents what are known as a species.
• Described species range from 1.7 to 1.8 million.
• This range refers to biodiversity the number and types of organisms present on Earth.
• New species are identified as new areas are discovered.
• Millions of plants and animals have local names specific to regions or countries.
• Standardization is needed to give a particular organism one universal name.
• Nomenclature is the process of standardizing names for living organisms.
• Nomenclature relies on correct organism description and identification.
• Scientists follow procedures to assign a scientific name to each organism.
• The International Code for Botanical Nomenclature (ICBN) governs plant scientific names which are based on agreed upon principles and criteria.
• The International Code of Zoological Nomenclature (ICZN) governs animal naming.
• Scientific names ensure each organism has a unique name.
• Organism descriptions should allow anyone to assign the same name.
• Scientific names have generic names and specific epithets.
• Binomial nomenclature is a two-component naming system.
• Carolus Linnaeus developed binomial nomenclature.
• Mango's scientific name is Mangifera indica and demonstrates binomial nomenclature.
• Mangefera is the genus, and Indica is a species, or a specific epithet.
• Biological names are generally in Latin and written in italics irrespective of their origin.
• The genus is the first word in a biological name, followed by the specific epithet.
• Underline the words in the biological name separately when handwritten, or print in italics to indicate Latin origin.
• The genus starts with a capital letter, and the specific epithet starts with a small letter, ex Mangifera indica.
• The author's name is written in an abbreviated form after the specific epithet, ex Mangifera indica Linn, and the species was first described by Linnaeus.
• Organism study is difficult because of the amount of living organisms, so it's necessary to make it possible.
• Classification groups organisms into categories based on observable characteristics which is a process of classification.
• These terms link characters with that organism group.
• Categories like 'Dogs,' 'Cats,' 'Mammals,' 'Wheat,' 'Rice,' 'Plants,' and 'Animals' are convenient for studying organisms.
• The scientific term for these categories is taxa.
• 'Plants' and 'Wheat' also are taxa.
• 'Animals', 'mammals', or 'dogs'are taxa at different levels.
• Organisms can be classified into different taxa based on characteristics.
• Taxonomy describes the classification process.
• Modern taxonomic studies use external/internal structure, cell structure, development, and ecological information.
• Characterization, identification, classification, and nomenclature are basic to taxonomy.
• Humans have always been interested in knowing more and more about organisms, particularly with reference to their own use such as early classifications that were based on the 'uses' of various organisms for basic needs of food, clothing and shelter.
• Humans were also interested in relationships among organisms' diversities.
• Systematics describes the study of organism relationships.
• Systema comes from the Latin word 'systema' and means systematic arrangement of organisms.
• Systema Naturae was used by Linnaeus as the title of his publication.
• Systematics later included identification, nomenclature, and classification.
• Systematics considers evolutionary relationships between organisms.

Taxonomic Categories

• Classification is a multi-step process involving a hierarchy where each step represents a rank or category.
• A taxonomic category is part of an overall taxonomic arrangement.
• Taxonomic hierarchy includes all categories.
• A taxon is each category as a unit of classification.
• Taxon is plural.
• Insects have three pairs of legs.
• Insects can be recognized, classified, ranked, and categorized.
• Groups represent categories.
• Categories denote rank.
• Taxonomical studies have led to common categories such as kingdom, phylum/division, class, order, family, genus, and species.
• Both plant and animal kingdoms have species as the lowest category.
• The basic need is the knowledge of individual or group characteristics for identifying similarities and dissimilarities.

Species

• Taxonomic studies group individual organisms with similarities as a species.
• One should be able to distinguish one species from another species based on morphological differences.
• Indica, tuberosum, and leo are specific epithets.
• Mangifera, Solanum, and Panthera are genera.
• Genera represent a higher taxon level with one or more than one specific epithet which represent different organisms, but having morphological similarities.
• Panthera has species called tigris.
• Solanum has species like nigrum and melongena.
• Humans belong to the species sapiens and the genus Homo.
• The scientific name for humans is Homo sapiens.

Genus

• Genus is a group of related species with common characters.
• Genera have clusters of closely related species.
• Potato and brinjal are species and belong to the genus Solanum.
• Lion (Panthera leo), leopard (P. pardus), and tiger (P. tigris) have common features species are of the Panthera genus.
• Felis includes cats.

Family

• A family has genera that are related that have less similarities compared to genus and species.
• Families are characterized on both characteristics of both vegetative and reproductive features of plants.
• Three genera Solanum, Petunia, and Datura are plant genera which are placed in the Solanaceae family.
• Genera Panthera and Felis are animal genera which are in the felidae family.
• Cat and dog similarities and differences place them in the Felidae and candidae families.

Order

• Species, genera, and families are based on similar characters.
• Higher taxonomic categories like order are based on character aggregates.
• An order as a high category family has similar characters.
• Characters are less similar in genera included in a family.
• Plant families Convolvulaceae and Solanaceae belong to the order of Polymoniales based on floral characters.
• The order Carnivora contains animal families Felidae and Canidae.

Class

• This category includes related orders.
• The order Primata with monkeys, gorillas, and gibbons, is in class Mammalia.
• Order Carnivora is also in the Mammalia class.
• Mammalia include other orders.

Phylum

• Classes of animals, including fishes, amphibians, reptiles, birds and mammals constitute the next higher category known as Phylum.
• Chordata describes the notochord and dorsal hollow neural system.
• Division describes plants with classes with a few similar characters.

Kingdom

• Animals with various phyla belong to Kingdom Animalia.
• Kingdom Plantae has all plants from various divisions.
• The two groups are animal and plant kingdoms.
• Species to kingdom are ascending taxonomic categories.
• Taxonomists developed sub-categories for scientific placement of taxa.
• Arrangement is based on characteristics.
• Going higher from species to kingdom reduces characteristics.
• Lower taxa share more characteristics.
• Relationship determination is harder if the category is higher.
• Classification becomes more complex.

Taxonomy Summary

• Millions of identified plants and animals exist, but many are unknown.
• Organism range in size, color, habitat, physiology and morphological features define living things.
• Biologists use rules and principles to identify, name, and classify organisms.
• Taxonomy is knowledge of these aspects.
• Agriculture, forestry, and industry benefit from taxonomic studies.
• International codes govern taxonomy basics (identification, naming, and classification).
• Resemblances and differences identify organisms by their scientific name with two words.
• Organisms have a place in the classification system with many categories/ranks called taxonomic categories or taxa.
• Categories constitute a taxonomic hierarchy.