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Classification

Classification. Learning Objectives. The biological classification of species To include the taxonomic hierarchy of kingdom, phylum, class, order, family, genus and species AND domain. The binomial system of naming species and the advantage of such a system

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Classification

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  1. Classification

  2. Learning Objectives • The biological classification of species • To include the taxonomic hierarchy of kingdom, phylum, class, order, family, genus and species AND domain. • The binomial system of naming species and the advantage of such a system • (i) the features used to classify organisms into the five kingdoms: Prokaryotae, Protoctista, Fungi, Plantae, Animalia to include the use of similarities in observable features in original classification. • (ii) the evidence that has led to new classification systems, such as the three domains of life, which clarifies relationships to include the more recent use of similarities in biological molecules and other genetic evidence AND details of the three domains and a comparison of the kingdom and domain classification systems. • The relationship between classification and phylogeny (covered in outline only at AS level)

  3. Classification, phylogeny and taxonomy Key definitions to match up and learn! Taxonomy Phylogeny Classification The process of sorting living things into groups The study of principles of classification The study of evolutionary relationships between organisms

  4. Early systems Aristotle – Plants or Animals Animals split into groups: • Live and move in the water • Live and move on land • Move through the air Linnaeus and other scientists: • Observable features • Use of microscopes

  5. Grouping species together – principles of classification • Classification –the grouping of organisms often on the basis of simple observable features • Taxonomy – the study of biological classification • Artificial classification Divides organisms by what is useful at the time e.g. Colour, size, no of legs (analogous features) • Natural classification Based on the evolutionary relationships between organisms and their evolutionary descent e.g. Shared features and derived from ancestors (homologous characteristics)

  6. The concept of a species Mule – result of horse & donkey mating. Hybrid. Mule has 63 chromosomes & is nearly always infertile A species is the basic unit of classification. Individuals of the same species are capable of breeding to produce living offspring which themselves are fertile Horse – 64 chromosomes in a body cell, 32 chromosomes in a gamete Donkey – 62 chromosomes in a body cell, 31 in a gamete

  7. Naming species Carl Linnaeus – father of taxonomy • Binomial naming system Uses two Latin names: Generic (genus organism belongs to) Specific (species that the organism belongs to) There are rules! Handwritten – Generic name starts with a capital, both parts underlined. In type – in italics, generic name starts with a capital

  8. The five kingdoms Can you name them?

  9. Ordering taxonomic ranks – using eight taxa Number of similarities Largest group Distant ancestor • Do I have Domain • King Kingdom • Prawn Phylum • Curry Class (e.g. Mammals) • Or Order • Fat Family • Greasy Genus • Sausages Species Smallest group Recent ancestor

  10. June 2010 F212

  11. Phylogeny The study of how closely different species are related. Grouping based in evolutionary relationships and evolutionary history A species is the smallest group that share a common ancestor Common ancestor of humans and chimpanzees

  12. Classifying organisms based on their phylogeny is known as cladistics

  13. Molecular Evidence • DNA Comparison of DNA sequences in common genes • Cytochrome C A protein used in respiration. All organisms except chemosynthetic organisms must respire so therefore contain this protein.

  14. DNA and protein analysis can give evidence for phylogenies • The lengths of the branches in this tree are drawn proportional to the number of differences in the primary sequence. • The tree clearly reveals the three main kingdoms of eukaryotes: fungi, animals, and plants. • Such trees tend to agree closely with those constructed by evolutionary biologists using morphological data, and provide independent evidence of common descent.

  15. LUCA • Last Universal Common Ancestor • All life had one common ancestor – we know this because all life on earth uses the same genetic code to determine the amino acid sequence of its proteins

  16. The three domains Carl Woese 1990 Ideas based on new evidence from detailed studies of RNA Bacteria are fundamentally different from Archaea and the Eukaryotae

  17. The three domain model Within the eukaryota, the classification from Kingdom-species remains UCMP History of Life Animation re 3 domains

  18. Bacteria • Very different to everything else • Different cell membrane structure • Different structure to the flagella • Different enzymes to make RNA e.g. RNA polymerase • Naked DNA without proteins (histones) • Different method of DNA replication and building RNA

  19. Archea • Share some features with eukaryotes • Similar enzymes to make RNA • Similar method of DNA replication and building RNA • Production of some proteins that bind to DNA UCMP Intro to Archea

  20. Bacteria Archea Eukarya LUCA

  21. Adaptations Organisms need features which help them survive in the environment. Natural selection is the mechanism that enables them to adapt. Adaptations can be • Anatomical • Behavioural • Physiological

  22. Anatomical Adaptations Examples include • Size • Body shape • Camouflage • Mimicry • Colour • Surface covering

  23. Behavioural Adaptations • Courtship rituals • Migration patterns • Hibernation • Innate and learned behaviour • Survival strategies such as playing dead Possum playing dead

  24. Physiological Adaptations • Making venoms and poisons • Making antibiotics • C4 plants use a different metabolic pathway to carry out photosynthesis to reduce water loss

  25. Convergent Evolution Some anatomical adaptations in different species are very similar although have arisen via different paths. This creates Analogous Structures Examples include • Fish and whale fins, • Octopus and mammalian eyes Convergent evolution leads to different species appearing to have similar features because they are subject to similar selection pressures e.g. moving in water.

  26. Marsupials and Placentals The division between marsupials and placentals occurred about 100MYA They have very different reproductive strategies but there is much evidence for convergent evolution between the 2 groups Mammals that lay eggs Duck billed platypus/ Echidna

  27. Marsupial and Placental Moles • Both live in burrows and need to dig them with well adapted front limbs • Streamlined body shape • Soft fur reduces friction

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