Unit 2 – Diversity of Life • Millions of species (2-4.5 million) exist on planet earth (huge amount of biodiversity). • Classifying all these species helps make sense of all the biodiversity. • Many species have become extinct in the past. • Many existing species are becoming extinct before we even know they exist! Some of these species could be important for our species in terms of medical or ecological significance. • Taxonomy – the science of naming and classifying organisms • Taxon – a group of organisms in a classification system
Binomial Nomenclature Two-word standard naming system for all known organisms Based on the dead language latin – dead because it is not spoken any more and thus doesn’t change over time Two part name – genus + species: ex. Homo sapiens, Canislupis Universal over all languages so species identification cannot be mistaken from language to language. a scientific (biological) name can help distinguish common name confusion.
What is a Gopher? In Florida, a gopher is this: Species name: Gopheruspolyphemus Species name: Urocitellus richardsonii In Saskatchewan, a gopher is this:
Linnaeus Carl von Linne (Carolus Linnaeus – he “Latinized” his name) – Swedish botanist: developed the Linnaean system of classification (binomial nomenclature) His system of naming organisms is still used today 3 rules used: Genus – always capitalized, ex: Canis Species – always not capitalized ex: lupis Entire species name (genus and species) is underlined (if handwritten) or italicized (if typed) Underlined (or italicized) so that the scientific name stand out from rest of the text present
7 Levels of Classification (Taxons) Kingdom – ex: Animals Phylum (animals) / Division (plants) - ex: Chordata Class – ex: Mammalia Order – ex: Primates Family – ex: Hominidae Genus – ex: Homo Species – ex: sapiens “King Phillip Came Over For Graduation Speeches”
Questions 1-3, page 521 • What is binomial nomenclature? - It is a system that gives every species a unique two-part name that identifies it. The first part is the genus, and the second part is the species descriptor. • Name each taxon in the Linnaean system of classification, from most general to most specific. - kingdom, phylum, class, order, family, genus, species • What are some limitations of the Linnaean classification system? - It only accounts for physical and structural similarities between organisms, which can be the result of convergent evolution and therefore not indicative of relatedness.
Questions 4-5, p521 • How is a scientific name similar to an address that includes city and state? - A state (or province) has many cities as a genus has many species. Like species descriptors, city names cannot be used alone because the same city names can occur in different states (or provinces), as with Portland (Maine and Oregon). • Which two species are more closely related: Ursusmaritimus, Ursusamericanus, or Bufoamericanus? - Ursusmaritimus(polar bears) and Ursusamericanus (black bear) are most closely related; they belong to the same genus.
Question 6, p521 During his voyage, Charles Darwin collected thousands to organisms, which he classified using the Linnaean classification system. How did this system help him share his findings with other naturalists? - Others could understand the relationships between organisms, such as Darwin’s finches, and there was uniformity in temrs of language. Had he used common names alone, they would have required translation into many languages.
Dichotomous Keys Dichotomous keys are used to identify objects or organisms that have already been described by another scientist. As its name implies (di- means "two"), a dichotomous key is made up of paired statements. Each pair of statements divides the objects to be classified into two categories. This means that each object must fit into one category or the other, but not both.
# of Kingdoms? • 1753: Two kingdoms – Animalia & Plantae • 1866: Three kingdoms – Animalia, Plantae & Protista • 1938: Four kingdoms - Animalia, Plantae, Protista, & Monera • 1959: Five kingdoms - Animalia, Plantae, Protista, Monera & Fungi • 1977: Six Kingdoms - Animalia, Plantae, Protista, Bacteria, Fungi, & Archaea
3 Domains of Life • Domain – Bacteria • - One kingdom: Bacteria • Single celled prokaryotes (lack a nucleus and organelles) • One of the largest group of organisms on earth • Domain – Archaea • One Kingdom: Archaea • Single celled prokaryotes (lack a nucleus and organelles) • Live in extreme environments: deep sea vents, hot geysers, Antarctic waters, salty lakes, acidic environments
Domain – Eukarya • Four kingdoms: • Plantae • Protista • Fungi • Animalia • Single-celled (protista) or multicellular (fungi, plantae & animalia) • Eukaryotic: cells possess a nucleus and organelles
Questions 1-2, page 535 • Why is classification of life considered a work in progress? - Scientists are always finding more information about organisms that forces a re-examination of classification schemes. • What kingdoms are included in each of the three domains in the modern tree of life? • Bacteria: bacteria • Archaea: archaea • Eukarya: protista, fungi, plantae, animalia
Questions 3-4, page 535 • If you come cross across an unusual single-celled organism, what parts of the cell would you study to classify it into one of the three domains? - Nucleus (or lack thereof) and cell wall • Explain, using the traditional definition of species, why it is difficult to classify some bacteria and archaea at the species level. • A species can be defined as an interbreeding group of organisms that produce fertile offspring. But bacteria and archaea do not breed to produce offspring; they reproduce by binary fission. In reproduction, as it is generally defined, parents also pass genetic material to their offspring. However, many bacteria and archaea can take up genetic material from their environment – a transfer of genes outside of typical reproduction that does not occur in eukaryotes.
Question 5, p535 • History of Life – The Archaea lineage may include the first life on Earth, which began under much different environmental conditions from those present today. What characteristics of archaea help support this statement? - Archaea exist in extreme environments that are similar to those of early Earth.