Essential idea: Species are named and classified using an internationally agreed system. Evolution and Biodiversity 5.3- Classification and Biodiversity Nature of science: Cooperation and collaboration between groups of scientists scientists use the binomial system to identify a species rather than the many different local names. (4.3) International-mindedness: There are international codes of nomenclature and agreements as to the principles to be followed in the classification of living organisms. Puma All are Felis concolor Mountain Lion Cougar Florida Panther The adoption of a system of binomial nomenclature is largely due to Swedish botanist and physician Carolus Linnaeus (1707 1778). Published Systema Natura in 1758. Gave binomials for all species known at that time. Based on physical characteristics (morphology). Linnaeus also defined four groups of humans, and the divisions were based on both physical and social traits. "Europæus albus" (white European), "Americanus rubescens" (red American), "Asiaticus fuscus" (brown Asian) and "Africanus Niger" (black African). 1
By 21st-century standards, his descriptions can be regarded as racist. How does the social context of scientific work affect the methods and findings of research? Is it necessary to consider the social context when evaluating ethical aspects of knowledge claims? The binomial system of names for species is universal among biologists and has been agreed and developed at a series of congresses. The IBC of Vienna in 1905 voted to accept his naming convention. Since then both the IBC and ICZ have been the bodies that oversee the international efforts to maintain consistent naming conventions and use of taxon. Periodically the congresses meet to discuss issues affecting classification. When species are discovered they are given scientific names using the binomial system. Scientific name is written in italics or underlined. Genus is always capitalized, species is always lowercase. (Ex: Homo sapiens or Homo sapiens) When species are discovered they are given scientific names using the binomial system. ex: Canis = dog lupus = wolf latrans = to bark lupus = wolf familiaris = familiar Taxonomists classify species using a hierarchy of taxa. Is a Koala bear a bear? Is a Jellyfish a fish? Morphological Species Concept Used by Linnaeus Uses anatomical features Physically different Problem- individual variation 2
Biological Species Concept Proposed by Ernst Mayr (1942) Interbreeding natural populations that are reproductively isolated Produce viable, fertile offspring Problems o Asexual organisms o Geographically isolated populations o Extinct species? Alternative Concepts of Species Ecological-defined by its niche (role) Pluralistic-defined by the most important factors that distinguish the species Geneological- defined by the genetic history All organisms are classified into three domains. Domain Bacteria (Eubacteria) Domain Archaea (Archaebacteria) Domain Eukarya (Eukaryotes) Six Kingdom System Archaebacteria Eubacteria Protista Fungi Plantae Animalia The principal taxa for classifying eukaryotes are kingdom, phylum, class, order, family, genus and species. The principal taxa for classifying eukaryotes are kingdom, phylum, class, order, family, genus and species. Taxon : group with similar traits o Kingdom Phylum Class Order Family Genus Species Kids Play Chess On Freeways Get Smashed 3
In a natural classification, the genus and accompanying higher taxa consist of all the species that have evolved from one common ancestral species. Taxonomists sometimes reclassify groups of species when new evidence shows that a previous taxon contains species that have evolved from different ancestral species. Previously used a five kingdom classification. Previously placed archaebacteria as precursor to bacteria Today archaebacteria more closely related to eukaryotes Natural classifications help in identification of species and allow the prediction of characteristics shared by species within a group. Mountain Lion: Animalia-Chordata-Mammalia-Carnivoras-Felidae-Felis-concolor Wolf: Animalia-Chordata-Mammalia-Carnivoras-Canidae-Canis-lupus Dog: Animalia-Chordata-Mammalia-Carnivoras-Canidae-Canis-lupus-familiaris Application: Classification of one plant and one animal species from domain to species level. Human: o Eukaryote o Animalia o Chordata o Mammalia o Primate o Hominidae o Homo o sapiens Application: Classification of one plant and one animal species from domain to species level. Homework: Classify a plant of your choice and describe why it is in each taxa. (use chart as example) Taxa Level (List Specimen) Describe charateristics at this level Domain Kingdom Phyla Class Order Family Genus Species Application: Recognition features of bryophyta, filicinophyta, coniferophyta and angiospermophyta. 4
Application: Recognition features of porifera, cnidaria, platylhelmintha, annelida, mollusca, arthropoda and chordata. Application: Recognition of features of birds, mammals, amphibians, reptiles and fish. Skill Skill: Construction of dichotomous keys for use in identifying specimens Help organize organisms by characteristics Used to name organisms Skill Skill: Construction of dichotomous keys for use in identifying specimens Dichotomous Keys o Help organize organisms by characteristics o Used to name organisms 5