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5.3 Classification of 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 Understanding: The binomial system of names for species is universal among biologists and has been agreed and developed at a series of congresses When species are discovered they are given scientific names Taxonomists classify using taxa All organisms classified into 3 domains Principal taxa for classifying eukaryotes are: kingdom, phylum, class, order, family, genus, species In a natural classification the genus and higher taxa have all evolved from one common ancestor Taxonomists sometimes reclassify groups of species when new evidence shows a previous taxon contains species evolved from a different ancestor Natural classifications help in identification of species and allow the prediction of characteristics shared by species within a group Applications Classification of one plant and one animal species from domain to species level External recognition features of bryophytes, filicinophytes, coniferophytes and angiospermophytes Recognition features of porifera, cnidaria, platyhelminthes, annelide, mollusca and arthropoda, chordata Recognition of features of birds, mammals, amphibians, reptiles and fish Skills Construction of dichotomous keys for use in identifying specimens
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Why are supermarkets organised like this?
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All living things arranged into groups according to their similarities
Classification… All living things arranged into groups according to their similarities
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HOW DO WE IDENTIFY LIVING THINGS?
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Living things… Nutrition Metabolism Growth Response Excretion Homeostasis Reproduction
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The 3 domains Eukaryotes Eubacteria (prokaryote) Archaea (prokaryote)
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What is the difference? Feature Bacteria Archaea Eukaryota Histones associated with DNA Absent Proteins similar to histones bound to DNA Present Presence of introns Rare or absent Present in some genus Frequent Structure of cell walls Made of chemical called peptidoglycan Not made of peptidoglycan Not always present Cell membrane differences Glycerol-ester lipids; unbranched side chains; d-form of glycerol Glycerol-ether lipids; unbranched side chains; l-form of glycerol histones are highly alkaline proteins found that package and order the DNA into structural units called nucleosomes Introns are noncoding sections of an RNA transcript, or the DNA encoding it, that are spliced out before the RNA molecule is translated into a protein. The sections of DNA (or RNA) that code for proteins are called exons. 2 extra oxygens on D form Different bonds ester =
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What is the difference? Feature Bacteria Archaea Eukaryota
Histones associated with DNA Absent Proteins similar to histones bound to DNA Present Presence of introns Rare or absent Present in some genus Frequent Structure of cell walls Made of chemical called peptidoglycan Not made of peptidoglycan Not always present Cell membrane differences Glycerol-ester lipids; unbranched side chains; d-form of glycerol Glycerol-ether lipids; unbranched side chains; l-form of glycerol 2 extra oxygens on D form Different bonds ester =
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Eukaryotes are classified using principal taxa
Classification Eukaryotes are classified using principal taxa Kingdom Phylum Class Order Family Genus Species K P Crisps Only For Good Students
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Try to guess who this is…
Who am I? Try to guess who this is… Kingdom Phylum Class Order Family Genus Species Animalia Chordata Mammalia Carnivora Canidae Canis lupus
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The same species can have many different local names.
Naming species The same species can have many different local names. Lords and ladies Cuckoo pint Devils and angels Cows and bulls Willy Lily Snakes meat Arum maculatum
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Naming species Cooperation and collaboration between scientists
Ensures all scientists use same names Decided by different animal and plant congresses
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Use two names: the genus and species
Binomial system Use two names: the genus and species Rules: Genus name begins with upper case letter and species name with lower case Italics Can be abbreviated once if used already: A.maculatum
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Natural classification
Classify organisms in a way that closely follows evolution Members of a genus should have a common ancestor Members of the group share many characteristics Unnatural classification – grouping birds, bats and insects because they fly Flight evolved separately in these groups and they have very big differences otherwise
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Advantages of natural classification
Identification of species is easier Go through each taxa step by step – assign a kingdom, then a phylum etc… Dichotomous keys can be used to help with the process Could do no easily with unnatural classification 2. Prediction of characteristics Inherited similar characteristics from common ancestor Could not do this if we used unnatural classification E.G find a new species of bat – we know it has mammalian features (could not do if grouped with birds)
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Reclassification New evidence may show that members do not share a common ancestor Split group up into more taxa (or two groups are found to be more similar – merge the groups)
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Creating the dichotomous key
All living things are grouped due to their similarities…
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What are these? BIRDS
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What are these? MAMMALS
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What are these? FISH
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We can create a dichotomous key to split these animals up.
To do this we need to ask questions about them to find their differences. How are fish, mammals and birds different?
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BIRDS Feathers MAMMALS Fur FISH Scales
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This is how we construct a dichotomous key…
Does it have scales? yes Does it have feathers? no yes no
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Your task You need to be able to read both types of dichotomous key and be able to create your own. Complete the classification worksheet Create your own classification key using 5 animals of your choice Look at page 265 in your book turn your key from part 2 into the second type of key.
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