Classification of Biodiversity - Biology 2515

Classification of Biodiversity - Biology 2515

Classification of Biodiversity Subtopic 5.3 The need for an universal naming system. About 8.7 million (give or take 1.3 million) is the new, estimated total number of species on Earth -- the most precise calculation ever offered -- with 6.5 million species on land and 2.2 million in oceans. Science daily news. Are the dogs below of same or

different species? Breeds The term breed refers to a domesticated variety of an organism that is a subgroup of a species. Species are often divided into subgroups. There are a lot of variations within species. What do you call this M animal? a

m u P Co r a ug O U

N TA IN LI O N r e h t n

a P An organism may have many common names. Common name Mountain lion, puma, cougar, or panther. Scientific name Felis concolor A common name may refer to different organism in

another country. In the United Kingdom, the word buzzard refers to a hawk. In the United States, buzzard refers to vulture. Hawk Vulture Sometimes common names are not very accurate. Starfish is not a fish bur rather an echinoderm.

Horned Owls do not have horns. Sea cucumbers are not fruits. Species are named and classified using an internationally agreed system. Aristotle (384322 BCE) divided the living world into plants and animals, but his system was hardly useful and workable. Carl Linnaeus, a Swedish botanist (1707-1778), was formalized a binomial (meaning two names) system to identify organisms.

He is considered the father of taxonomy, the science of naming organisms. TOK How does the social context of scientific work affect the methods and findings of research? Social context and sensitivities have great importance when considering the impact of scientific research and may even discourage research in certain areas. In his system of classification, Linnaeus regarded humans as one species but divided into four sub-groups. While his classification of other organisms was based entirely on physical features, his classification of humans also included social and behavioral

characteristics along racial lines and clearly favored those of 'Europeanus' origin. Such a classification was not controversial at the time when ethical and social issues were of little importance to scientists, but would be entirely unacceptable by present-day standards Late 19th century, the first international congress on the naming of plants and animals was held. Science is precise. When we talk about a particular organism, it is important that everyone understands exactly what organism we are referring to.

These conferences are still held every few years to confirm the names of newly found species, and to discuss the binomial system. Binomial System Is the common system for the naming of living organisms. It always follows the Genus species format. A genus is a group of species that share characteristics. For example, the genus Macropus, or 'big foot', is a genus of kangaroos that all have big hind legs. The species name is specific to that organism, and may refer

to a specific trait of that particular organism. For example, Macropus rufus is a red kangaroo. Rules that scientists follow when it comes to naming a species: Genus name starts with a capital (upper case) letter. Species name starts with a lower case letter. Genus name is always written before the species name.

The complete name, i.e. genus and species, should be written in italics or underlined. International Mindedness International nomenclature of organisms A scientist or group that discover a new species have the right to suggest a binomial name for their discovery. This name has to be approved by one of a number of international bodies before being accepted. These bodies have their roots in the International Zoological Congresses of the late 19th century. The International Code of Zoological Nomenclature is the global authority for animals and

there is a second body for plants, algae and fungi. These bodies decide on the binomial name. The need for such agreements is illustrated by the name Curculio fasciatus, which in the 18th century referred to seven different species of beetle around Europe. These species have now been reclassified with their own unique names using accepted binomial nomenclature. Taxonomy The branch of science concerned with classification, especially of organisms; systematics. The classification of something, especially organisms.

The hierarchy of taxa. The genus combines organisms that resemble each other in one or more characteristics. For example, the big hind legs in the kangaroo genus Macropus. The genera (plural of genus) can be grouped into families, and families can be grouped into orders. Each of the groupings is called taxon (plural taxa). As we go up each level, to the level of a domain, each higher level includes a larger group of organisms. In other words, there is a hierarchy of taxa.

Levels of Taxonomy Domain Highest level of taxonomy (most inclusive/broadest). Before DNA sequences could be used to classify organisms, there were only two groups: Prokaryotes (Latin: Prokaryota), organisms without a nucleus, and Eukaryotes (Latin: Eukaryota), those with a nucleus. In 1977, while using DNA sequencing information to group organisms, an evolutionary microbiologist called Carl Woese discovered that organisms grouped together into Prokaryotes actually had two separate ancestors).

In 1990 he proposed the division of organisms into three domains: eubacteria, archaea and eukaryote. Main characteristics of each domain: Characteristics Eubacteria Archaea Eukaryote Histones (proteins Absent associated with DNA)

Present in some species (similar to histones found in Eukaryota) Present Introns Absent Present in some genes

Present Cell membrane Glycerol-esters of lipids, D-form of glycerol Glycerol-ether lipids, L-form of glycerol

Glycerol ester lipids, D-form of glycerol Cell wall Peptidoglycan Not made of peptidoglycan Not made of peptidoglycan,

sometimes absent Domain Archaea Usually unicellular organisms that live in extreme habitats, such as hot water springs, deep earth sediments, and lakes or pools with extremely high salt concentrations. Phylogenetic Tree show evolutionary relationships and ancestry. Classification Of the three domains, only the Eukaryota have been further classified

into kingdoms. Animalia, Plantae, Fungi and Prototista are widely accepted by most biologists as the four kingdoms that make up the eukaryotic domain. Examiner Tip You are expected to know the classification of one animal and one plant species, from domain to species level. Animal (blue whale) and plant (garlic) classification. Taxon

Blue whale Garlic Domain Eukaryote Eukaryote Kingdom Animalia

Plantae Phylum Chordata Magnoliophyta Class Mammalia

Liliopsida Order Cetacea Asparagales Family Balaenopteridae Amaryllidaceae

Genus Balaenoptera Allium Species B. musculus A. sativum

Classification based on similarities and differences can be problematic. Crabs and barnacles share several characteristics that indicate they are more closely related to each other than either is to limpets Barnacle s Limpets Crabs

Natural Classification classification based on evolutionary relationships. A genus, and its accompanying higher taxa, consist of all the species that have evolved from one common ancestral species. This is called natural classification. Organisms may seem closely related at first, but when looking at other characteristics they do not. Ex: Whales, porpoises, sharks and other fish all have fins and swim. However, when considering other characteristics, this kind of grouping no longer makes sense. Whales and porpoises are mammals. Fish are a large group of freshwater and marine organisms that have bones, rather than sharks that have a skeleton made of cartilage. Today, the ancestry can also be confirmed by DNA and protein analysis, making the grouping of certain organisms much more reliable.

Sometimes new findings, such as DNA sequence analyses, reveal that the previous classification is wrong. Ex: the taxon may contain species that have evolved from different ancestors. In this case, taxonomists may reclassify groups of species according to the new evidence. Dichotomous Key A dichotomous key is a series of paired statements that guides the user to the identity (or allows the classification) of an item or organism. Dichotomy means splitting into two or a division into two groups. A dichotomous key can help you to quickly identify organisms. Dichotomous keys consist of a series of choices that lead the user to the correct name of a given item.

They may make use of yes or no questions, such as, 'Does the organism have 6 legs? Yes - go to step 3. No - go to step 2', but, there are always two choices in each step. Dichotomous keys in field guides rely on visible features to classify organisms. Each time you are given a choice of two features, but you should always follow the one that applies: each choice leads to another choice until the organism is narrowed down to its genus and finally to its species. Kingdom Plantae Consists of a large number of species (approximately 400,000), that can be grouped into several phyla. Be able to recognize features of the following four phyla:

bryophytes, filicinophytes, coniferophytes and angiospermophytes. Early plants The first plants evolved from an organism much like the multicellular green algae living today. The earliest plants were similar to todays mosses. They had simple structures and grew close to the damp ground.

How is the Plant kingdom organized? It is divided into four groups based on 3 features: Water-conducting tissue Seeds Flowers The 4 groups are: 1) Bryophytes 2) Seedless Vascular

plants Seed plants: 3) Gymnosperms 4) Angiosperms Flowering plants Bryophytes Mosses, liverworts and hornworts. Group of non-flowering plants. Typically 110 cm tall. Commonly grow close together in clumps or mats in damp or shady locations, such as swamps and moors.

Can tolerate really low temperatures, most common plant in polar regions. They do not have vascular tissue (the transport system in plants) for water transport. Draw water up by osmosis. At certain times, bryophytes produce spore capsules that are held above the plant on thin stalks. They do not have proper roots, but have rhizoids; thin threadlike outgrowths that hold them in the soil. However, these rhizoids are not used to absorb water or nutrients from the substrate. The leaves are not considered to be true leaves, due to the absence of vascular

tissue in most species. However, they contain chlorophyll and can carry out photosynthesis. Liverworts phylum Hepaticophyta Hornwort phylum anthocerophyta Filicinophytes Ferns and horsetails Have shallow roots. Their leaves are fronds.

Have a primitive vascular system. Made up of xylem carries (water upward from the roots to every part of the plant) and phloem (carries solutions of nutrients and carbohydrates produced by photosynthesis). They can grow in a small tree-like form, but do not have woody stems like trees. Their spores are produced in clusters on the underside of their fronds. Seedless vascular plants include: club mosses, horse-tails and ferns.

Seedless vascular plants have true leaves, stems and roots. Club mosses phylum Lycophyta Fossils formed coal beds. Horse-tails Ferns phylum Pterophyta Life cycle of Vascular Plants

Have a life cycle in which the diploid sporophyte is the dominant stage. Fertilization requires at least a thin film of water, allowing the sperm to swim to the eggs. Coniferophytes - conifers They are gymnosperms Their seeds are not enclosed in an ovary . They are cone-bearing seed trees with vascular tissue. The trees are made up of wood and often have narrow leaves with a thick waxy cuticle.

Conifers are monoecious plants. They produce both male and female reproductive structures or cones on the same plant. They reproduce sexually by releasing pollen from male cones, which is carried by the wind to the female cones where ovules are fertilized to form seeds. Typical examples of conifers include cedars, Douglas fir, cypresses, redwoods, spruces and yews. Gymnosperms cone bearers Include gnetophytes, cycads, ginkgoes, and conifers. Reproduce with seeds that are exposed.

Gymnosperms mean naked seed. Gnetophytes phylum Gnetophyta Cycads phylum Cycadophyta Found in tropical and subtropical places. Appeared in the Triassic Period. Ginkgoes phylum Ginkgophyta Common when dinosaurs were alive.

Conifers phylum Coniferophyta Most common gymnosperms. Most conifers are evergreens. Pines, spruces, cedars, sequoias, redwoods, junipers, and yews. Angiospermophytes flowering plants

There is a huge variety in this group, from small plants such as clover to massive oak trees. Many fruit trees and other important crop plants, such as wheat and cabbage, are included in this group. The stem may be woody as in the case of shrubs and trees. Flowering plants can be classified as monocotyledons or dicotyledons, and each of these has very specific leaf and root structures. Reproduction in angiosperms involves the transfer of pollen grains from anthers to the stigma of carpels, followed by fertilization of ovules found in the ovary. Once fertilized, the ovules form seeds, while the ovary

develop into a fruit. How angiosperms are classified: Monocots and Dicots. Named for the number of seed leaves, or cotyledons in the plant embryo. Monocots have one seed leaf, dicots have two. Woody and Herbaceous. Woody plants have a thick cell wall for support. Ex. Trees, shrubs, and vines. Herbaceous plants are smooth and nonwoody. Do not produce wood as they grow. Ex: dandelions, petunias, and sunflowers. Annual, Biennials and Perennials.

Plant life span. Annual plants grow, mature and reproduce in one season. Biennials grow, mature and reproduce for two seasons. Perennials live for more than two years. Monocots and dicots Woody and Herbaceous

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