Introduction to Biology and Ernst Mayr

• Biology is the study of life forms and processes.
• Humans first distinguished between living and non-living things, attributing awe and fear to both.
• Early progress in biological knowledge was limited by anthropocentric views.
• Detailed systems for identification, nomenclature, and classification arose out of necessity
• Recognizing similarities among organisms led to the understanding that all life is related and spurred biodiversity conservation.

Ernst Mayr (1904-2004)

• Ernst Mayr, was an evolutionary biologist
• Described as the "Darwin of the 20th century"
• He was one of the 100 greatest scientists of all time.
• He researched ornithology, taxonomy, zoogeography, evolution, systematics, and the history and philosophy of biology.
• Credited with making species diversity a central question in evolutionary biology
• Pioneered the accepted definition of a biological species.
• Received the Balzan Prize in 1983
• Internation Prize for Biology in 1994
• and the Crafoord Prize in 1999
• Mayr died at the age of 100 in 2004.

The Living World

• The living world has a diversity of living types.
• Habitats range of living organisms, from cold mountains to hot springs.
• Life evokes wonder, from galloping horses to attacking sharks.
• Ecological interactions prompt reflection on the nature of life.
• The first question to what is life is distinguishing between living and non-living
• The second is a philosophical question about the purpose of life.
• Science addresses the former.
• Growth, reproduction, and the ability to sense and respond to the environment are unique features of living organisms, as is metabolism, self-replication, self-organization, interaction, and emergence.
• Growth is an increase in mass and number of individuals.
• Plants continue to grow throughout their life
• Animals grow to a certain age.
• Cell division replaces lost cells.
• Unicellular organisms grow through cell division.
• Body mass increasing is considered growth.
• Non-living things grow by accumulating material on the surface, while living organisms grow from within
• Growth alone cannot define living organisms.
• Reproduction is the production of offspring with similar features.
• Organisms reproduce asexually.
• Fungi spread through asexual spores.
• Lower organisms like yeast and hydra use budding.
• Planaria regenerate via fragmentation.
• Fungi, algae, and mosses multiply by fragmentation.
• In unicellular organisms like bacteria and amoeba, reproduction equals growth (increased cell number/mass).
• Growth and reproduction are synonymous in single-celled organisms, making it harder to define two terms.
• Some organisms (mules, sterile worker bees, infertile human couples) do not reproduce: reproduction is not an all-inclusive defining characteristic of living organisms.
• Non-living objects cannot reproduce.
• Metabolism is a attribute of life.
• Living organisms are made of chemicals constantly being converted into other biomolecules through metabolic reactions.
• Metabolism is the sum of all chemical reactions in the body.
• Non-living objects do not exhibit metabolism.
• Metabolic reactions can be demonstrated in cell-free systems, but isolated reactions are not considered living.
• The cellular organization of the body defines life forms.
• Living things sense and respond to physical, chemical, or biological stimuli via sense organs.
• Plants respond to external factors such as light, water, temperature, and pollutants.
• Prokaryotes and eukaryotes can sense and respond to environmental cues.
• Photoperiod affects reproduction in seasonal breeders.
• All organisms are aware of surroundings.
• Humans have self-consciousness, making it the defining property of living organisms.
• Defining the living in humans is complicated in cases of patients in comas supported by machines and lacking self-consciousness.
• Living phenomena arise from underlying interactions at different levels of organization.
• Properties of tissues arise from interactions among constituent cells.
• Properties of organelles arise from interactions among molecular components.
• Living organisms are self-replicating, evolving, self-regulating interactive systems that can respond to external stimuli.
• Biology is the story of life and its evolution, with all organisms linked by shared genetic material.

Diversity in the Living World

• The living world contains a range of organisms.
• The number of known species ranges from 1.7-1.8 million, described as biodiversity.
• New organisms are continuously identified.
• Plants and animals are known by local names that vary by region.
• Standardized naming is needed to communicate about organisms.
• Nomenclature is the process of standardizing names.
• Identification is correctly describing the organism.
• Scientific names follow procedures established by scientists and agreed upon by biologists.
• The International Code for Botanical Nomenclature (ICBN) governs plant names.
• The International Code of Zoological Nomenclature (ICZN) governs animal names.
• Scientific names ensure each organism has a unique name.
• Descriptions should enable people to identify the same name for an organism.
• Biologists use principles to provide scientific names.
• Each name has a generic name and specific epithet.
• Binomial nomenclature is a system of two-part naming developed by Carolus Linnaeus.
• The scientific name of mango is Mangifera indica.
  • Mangifera is the genus
  • indica is the species.
• Biological names are in Latin and written in italics, or Latinized regardless of origin.
• The first word is the genus, and the second is the specific epithet.
• Handwritten biological names are underlined separately, or printed in italics to show Latin origin.
• The genus starts with a capital letter, while the specific epithet starts with a lowercase letter.
• The author's name is abbreviated and written after the specific epithet.
  • For example, Mangifera indica Linn. means Linnaeus first described the species.
• Classification groups organisms into categories based on observable traits since it is nearly impossible to study all the living organisms.
• For instance, groups such as dogs, cats, or insects are recognizable.
• Each term carries associated characteristics.
• Scientific term for categories is taxa
• A dog is a mammal, and mammals are animals.
• 'animals', 'mammals', and 'dogs' are taxa at different levels.
• Taxonomy is the classification of all living things based on their characteristics.
• Includes external and internal structure, cell structure, developmental processes, and ecological information.
• Characterization, identification, classification, and nomenclature are basic to taxonomy.
• Human interest in taxonomy stems from the need to understand organisms, especially for food, clothing, and shelter.
• Early classifications were based on the uses of organisms.
• Systematics studies relationships among organisms, and their diversity.
• The word systematics comes from the Latin word 'systema'.
• Linnaeus used Systema Naturae as the title of his publication.
• Systematics includes identification, nomenclature, classification, and evolutionary relationships.

Taxonomic Categories

• Classification is a process with a rank or category at each step.
• The taxonomic category is part of the taxonomic arrangement.
• The taxonomic hierarchy is all of the categories.
• The unit of classification represents a rank and is called a taxon (taxa pl.).
• Insects are classified by having common features like three pairs of jointed legs.
• Organisms are classified into groups, which are assigned a rank or category.
• These taxonomic groups/categories are biological and morphological.
• Taxonomical studies have led to common categories such as kingdom, phylum/division, class, order, family, genus, and species.
• Species is the lowest category for plants and animals.

Species

• Taxonomic studies classify individual organisms with fundamental similarities as a species.
• Species are distinguished by distinct morphological differences.
• Higher level is taxon or category is represented by genera.
• Each genus may have one or more specific epithets.
• Organisms in a genus share morphological similarities.
  • Human are grouped in the genus Homo.
  • The scientific name for human beings is Homo sapiens.

Genus

• Genera are aggregates of highly related species.
• Potato and brinjal belong to the genus Solanum.
• All species of the genus Panthera are lion (Panthera leo), leopard (P. pardus) and tiger (P. tigris).
• Genus Panthera differs from genus Felis which includes cats.

Family

• Family has related genera with similarities compared to genus and species.
• Families are based on reproductive/vegetative features of plant species.
• The family Solanaceae includes Solanum, Petunia, and Datura.
• The family Felidae includes lion, tiger, leopard(genus Panthera) and cats in the genus Felis.
• Cats and dogs are in separate families, Felidae and Canidae, despite some similarities.

Order

• Categories like species, genus, and families are based on number of similar characteristics.
• Higher taxonomic categories are based on the aggregates of characters.
• An assemblage of families with similar character is an order.
• Character similarities decrease as you go up a family
• Plant families Convolvulaceae and Solanaceae are included in the order Polymoniales with floral characters.
• Animal order Carnivora includes families like Felidae and Canidae.

Class

• Class is a category that includes related orders.
• Primata (monkey, gorilla, gibbon)and order Carnivora are in the class Mammalia

Phylum

• Classes comprising animals like fishes, amphibians, reptiles, birds, and mammals constitute a phylum.
• The phylum Chordata has common features like notochord and dorsal hollow neural system.
• Classes with similar characteristics are assigned to the division in plants

Kingdom

• Animals of various phyla are in the Kingdom Animalia.
• Plants from various divisions are in the Kingdom Plantae.

Taxonomic Categories

• The taxonomic categories ascend from species to kingdom
• Taxonomists have developed sub-categories within the hierarchy.
• As the number of common characteristics increase as we go higher from species to kingdom

Taxonomical Aids

• Taxonomic studies of plants, animals, and other organisms help in agriculture, forestry, industry and resource management.
• Precise classification and identification are required.
• Laborious laboratory and field studies are required.
• Taxonomic studies require collection of plant/animal specimens.
• Systematics studies and training rely on a fundamental basis on prime source
• Information is stored along with specimens for classification.
• Specimens are preserved for future studies.

Herbarium

• Herbarium is a storehouse of plant specimens that are dried, pressed, and preserved on sheets then arranged by accepted classification.
• Descriptions are included on herbarium sheets, making them a repository.
• Herbarium sheets has the date, collection place, names, family, and collector's name as well as quick references in taxonomic studies.

Botanical Gardens

• Botanical gardens contain living plants for the purpose of reference.
• Plants are grown for identification
• Each plant is labeled with their scientific name and family.
  • Kew (England)
  • Indian Botanical Garden, Howrah (India)
  • National Botanical Research Institute, Lucknow (India)

Museum

• Biological museums are educational.
• Collections of preserved plant and animal specimens are available for reference.
• Specimens are preserved in containers with solutions.
• Dry preservation is also used for specimens.
• Insects are preserved in insect boxes.
• Larger animals are stuffed and preserved.
• Museums also hold collections of skeletons.

Zoological Parks

• Zoological parks are where wild animals are kept in protected environments while under human care giving insight into behavior.
• Animals are provided conditions close to their natural habitats.

Key

• A key is a taxonomic aid for identifying plants and animals based on similarities and dissimilarities.
• Keys use contrasting characters in pairs called couplets, where one option is chosen and the other is rejected.
• Each statement in the key is a lead.
• Separate keys are needed for each taxonomic category such as family, genus, and species.
• Keys are generally analytical.

Other means of recording descriptions

• Flora, manuals, monographs, and catalogues.
• Flora provides accounts of habitat and distribution of plants in a given area.
• Manuals provide information for identifying species in an area.
• Monographs contain information on one taxon.