Carolus Linnaeus’ System for Classifying Organisms Lecture

Carolus Linnaeus’ System for Classifying Organisms Students will be able to: • Outline the main taxonomic groups and classification of selected organisms. • State the conventions for naming a species using binomial nomenclature. Key Vocabulary: Binomial name/nomenclature, Class, Classification, Common name, Domain, Family, Genus, Kingdom, Life process, Order, Phylum, Species, Taxonomy, Carolus Linnaeus’ System for Classifying Organisms Classification • Classification categorizes organisms into smaller groups. • In the same way that the books in a library are sorted according to their respective topics, science also has a way of categorizing the 1.5 million species that have been discovered so far. Carolus Linnaeus’ System for Classifying Organisms The Importance of Classification All living organisms are made up of cells and demonstrate each of the seven key life processes below: • movement These 7 life • respiration processes can be • sensitivity remembered using the acronym: • growth MRS GREN • reproduction • excretion • nutrition Carolus Linnaeus’ System for Classifying Organisms The Importance of Classification: • uses a hierarchy of levels based on the degree of similarity between species and how they carry out their life processes. • makes studying populations of organisms easier as they have many shared features. • newly identified can be placed into an appropriate group by observing how they carry out each life process. Carolus Linnaeus’ System for Classifying Organisms Comprehension Check: Can you... 1. List the 7 life processes used to classify organisms? 2. Explain why organisms need to be sorted? Carolus Linnaeus’ System for Classifying Organisms Comprehension Check: Answers Can you... 1. List the 7 life processes used to classify organisms? Movement, Respiration, Sensitivity, Growth, Respiration, Excretion, Nutrition 2. Explain why organisms need to be sorted? It makes them easier to study as organisms will have shared traits. Carolus Linnaeus’ System for Classifying Organisms Classification systems • Aristotle was the first person to classify living organisms over 2300 years ago. • He grouped: • animals based on their habitat into those with red blood and those into another group which he termed ‘bloodless’. • Plants as trees, shrubs or weeds. Carolus Linnaeus’ System for Classifying Organisms Classification systems • Aristotle’s classification system was improved upon in the 18th century by Carolus (Carl) Linnaeus. • Linnaeus, a Swedish naturalist is known as the 'Father of Taxonomy' due to his contributions to classification. Carolus Linnaeus’ System for Classifying Organisms Classification systems • His two most important contributions to taxonomy were: 1. Creation of a hierarchical classification system. 2. Invention of the binomial nomenclature, still in use today. Carolus Linnaeus’ System for Classifying Organisms Carl Linnaeus • Linnaeus collected plant and animal specimens. • In 1735, he developed a standardized way of grouping and naming the species in his collection. Carolus Linnaeus’ System for Classifying Organisms Carl Linnaeus • This led him to publish the first edition of Systema Naturae (The System of Nature), a guide explaining his method of classifying organisms. • As he continued to collect specimens, more editions of Systema Naturae were published. Carolus Linnaeus’ System for Classifying Organisms Carl Linnaeus • By the time the tenth edition of his guide had been published in 1758, Linnaeus had classified approximately 4,400 animal and 7,700 plant species using his binomial naming system. • This edition, was formally known as “The System of nature through the three kingdoms of nature, according to classes, orders, genera and species” and some of the most significant work contributing to Biology of its time. Carolus Linnaeus’ System for Classifying Organisms Comprehension Check: Can you... 1. Name the two individuals who contributed to the classification or organisms? 2. Outline the contributions each individual made to classification? Carolus Linnaeus’ System for Classifying Organisms Comprehension Check: Answers Can you... 1. Name the two individuals who contributed to the classification or organisms? Aristotle Carolus (Carl) Linnaeus 2. Outline the contributions each individual made to classification? Aristotle – Produced the first classification system Linnaeus - Refined Aristotle’s classification system and developed a hierarchial and binomial system Carolus Linnaeus’ System for Classifying Organisms Linnaeus' proposed that… • All organisms fitted into three broad groups called ‘kingdoms’ - animals, plants, and minerals. • Kingdoms divided into classes, which divided into orders and then into genera. • Each genus was finally divided into species. Kingdom Class Order Genus Species Carolus Linnaeus’ System for Classifying Organisms Linnaeus' Classification System • Each subsequent level contains a smaller number of organisms that are more similar to each other than that of the previous level. • Although there have been some modifications made to Linnaeus’ method, this basic structure is still used for classification in Biology today. Largest number of organisms (most diversity) K P C O G S Smallest number of organisms (least diversity) Carolus Linnaeus’ System for Classifying Organisms Modifications to Linnaeus’ Classification • Linnaeus originally had five levels of organization within his classification system – kingdoms, classes, orders, genera and species. • This has been modernized to include seven levels of classification (shown right) due to advances in technology and the discovery of more organisms. Carolus Linnaeus’ System for Classifying Organisms Comprehension Check: Can you... 1. Give the seven levels of classification in order? 2. Describe how the diversity of organisms changes with each subsequent level of classification? Carolus Linnaeus’ System for Classifying Organisms Comprehension Check: Answers Can you... 1. Give the seven levels of classification in order. Kingdom Phylum Class Order Family Genus 2. Describe how the diversity of organisms changes with each subsequent level of classification? With each level organisms become increasing similar Species Carolus Linnaeus’ System for Classifying Organisms The Taxonomic Hierarchy – in Detail 1. Domain • Also sometimes called super kingdoms or empires. • Domains are the highest taxonomic level with the largest number of different organisms. • There are three domains Archaea, Bacteria, and Eukarya.. Carolus Linnaeus’ System for Classifying Organisms The Taxonomic Hierarchy – in Detail 1. Domain • Bacteria and Archaea contain prokaryotes or single-celled organisms whose cells have no true nucleus. • Eukarya, are eukaryotic organisms whose cells contain a true nucleus and membrane-bound organelles. These organisms are multicellular. Carolus Linnaeus’ System for Classifying Organisms 2. Kingdom • Domains are split into kingdoms. • There are five kingdoms which are covered in this course – Monera, Protists, Fungi, Plants and Animals. • The kingdom Monera includes bacteria and cyanobacteria and belongs to the prokaryote domain. • The other four kingdoms belong to the Eukarya domain. • A kingdom contains a number of phyla. Carolus Linnaeus’ System for Classifying Organisms 3. Phylum • Each kingdom is divided into phyla (singular: phylum). • Organisms belonging to the same phylum will have a similar general body plan, both externally and internally. For example, the Animal (or Animalia) kingdom contains 36 major phyla. Carolus Linnaeus’ System for Classifying Organisms Taxonomic hierarchy 3. Phylum • Chordata - organisms which possess a notochord, a large rod which extends the length of the organism during at least part of their development. Including humans and other mammals, bony fish, reptiles and birds. • Arthropoda - organisms which have a hard exoskeleton, segmented bodies and many limbs. Including spiders, insects and crustaceans. • Mollusca - organisms which have a soft body and in some cases, a shell. Including clams, snails, octopus and squid. Carolus Linnaeus’ System for Classifying Organisms Taxonomic hierarchy 3. Phylum Phyla have also been developed and rearranged as scientists discover more species, more categories and subcategories are put in place. Carolus Linnaeus’ System for Classifying Organisms 4. Class Each phylum contains a number of different classes. For example, classes within the Chordata phylum include • Mammalia -warm-blooded organisms which feed their young milk from mammary glands. For example, humans, cats, dogs and many livestock. • Reptilia - cold-blooded organisms with four limbs and scaly skin. For example, lizards, crocodiles and snakes. • Osteichthyes – aquatic organisms, which lay eggs and have gills. For example, bony fish. Carolus Linnaeus’ System for Classifying Organisms 5. Order A class contains a number of orders. For example, there are many orders in the Mammalia class, such as: • Cetacea (whales, dolphins and porpoises) • Carnivora (meat-eaters, e.g. lions) • Primates (those with larger than average brains, e.g. monkeys, apes and humans) • Chiroptera (mammals capable of flight, e.g. bats) Killer whales (above) belong to the Mammalian class Cetacea Brown bears (left) belong to the class Carnivora Carolus Linnaeus’ System for Classifying Organisms Carolus Linnaeus’ System for Classifying Organisms 6. Family From an order, organisms are grouped into families. For example, the order of Primates (seen in the image below) contains the families Hominidae and Cercopithecidae. Carolus Linnaeus’ System for Classifying Organisms 7. Genus • Finally, each family is classified into genera (singular genus). These are the names that are most commonly used to describe an organism. • Each genus is classified into a number of species. • For example, within the primate family, the genus Homo for all human species or Pongo for the genus of the orangutan. Carolus Linnaeus’ System for Classifying Organisms 8. Species • The smallest taxonomic group is the species. A species is typically defined as a group of organisms that can interbreed and produce fertile offspring. • Species share a common gene pool and are usually reproductively isolated from other species. • This means that interbreeding is unlikely for behavioral, genetic or morphological reasons. Carolus Linnaeus’ System for Classifying Organisms 8. Species • Subspecies sometimes exist within a species. These groups are often capable of interbreeding. • Species which are closely related, for example, members of cat families, dog families and horse families are often able to interbred and form hybrids. Sumatran Tiger Panthera tigris sumatrae Siberian Tiger Panthera tigris altaica Bengal Tiger Panthera tigris tigris Carolus Linnaeus’ System for Classifying Organisms 8. Species • In many cases, these hybrids produce sterile offspring which are unable to breed. For example: • A horse and a donkey will produce a mule. • A lion and a tiger will produce a Liger or Tigroid (depending on the gender). • A lion and a leopard will produce a Leopon. A mule – cross between a horse and a donkey Carolus Linnaeus’ System for Classifying Organisms Comprehension Check: Can you... 1. Explain what is meant by taxonomic group? 2. The class of mammals includes organisms such as humans, cats and dogs. Give two other examples of organisms which belong in this class? 3. Name two organisms which belong to the chordate phyla? Carolus Linnaeus’ System for Classifying Organisms Comprehension Check: Answers 1. Explain what is meant by taxonomic group? A groups of organisms which have some features in common 2. The class of mammals includes organisms such as humans, cats and dogs. Give two other examples of organisms which belong in this class? Cows, horses, lions, zebra, bears, apes, monkeys 3. Name two organisms which belong to the chordate phyla? Humans and any of the organisms in answer 2. Carolus Linnaeus’ System for Classifying Organisms Binomial Nomenclature system • Organisms are often called different names depending on the region that they are found in. These names are called the common names. • Linnaeus overcame this problem when he proposed a system for nomenclature of living organisms which he called the binomial naming system. Carolus Linnaeus’ System for Classifying Organisms Binomial Nomenclature system • In this method, an organism has a name consisting of two parts. • The first part of the name is the genus and is written beginning with a capital letter. • The second part of the name is the species and is written in lowercase letters. • Both the genus and species are Latin and written in italics or underlined. This allows them to stand out to the reader. For example, the binomial name of human is Homo sapiens. Genus: Homo (man in Latin) Species: Sapiens (wise in Latin) Carolus Linnaeus’ System for Classifying Organisms Binomial Nomenclature system • When the name is first introduced in a body of text, the name is written in full, e.g. Homo sapiens. • However, any subsequent mention of the name is typically written using the initial of the genus, followed by a full stop, then species in lowercase letters e.g. H. sapiens. • In the case where a number of species belonging to the same genus are being discussed, scientists will often refer to the group by the genus followed by the abbreviation ‘sp’. Carolus Linnaeus’ System for Classifying Organisms Binomial Nomenclature system • For example, multiple species of bear may be referred to as Ursus sp. • This indicates to the reader that the information applies to many species of bear, rather than just Ursus americanus, the American black bear. Carolus Linnaeus’ System for Classifying Organisms Comprehension Check: Can you... 1. Describe how the scientific name of an organism is written? 2. Define the terms: a. b. Species Hybrid Carolus Linnaeus’ System for Classifying Organisms Comprehension Check: Answers Can you... 1. Describe how the scientific name of an organism is written? As two parts: the genus (written with a capital letter) and the species (all lowercase). The name itself is written in italics or underlined. 2. Define the terms: a. b. Species - a group of organisms which belong to the same gene pool, are able to interbreed and produce fertile offspring. Hybrid – organisms that are produced when two different species interbreed. Carolus Linnaeus’ System for Classifying Organisms Lesson Summary • The species is the basic unit of taxonomy/ classification. • Each species has a binomial (two-part) name made up of the genus and the species. • A species is a group of organisms capable of successfully producing fertile offspring. • Related species are placed into genera, which are placed into families, which are placed into orders, which are placed into classes, which are placed into phyla, which are placed into kingdoms.