Classification of Living Things Taxonomy Hierarchical Classification Binomial

Classification of Living Things Taxonomy, Hierarchical Classification, Binomial Nomenclature, Genetic Variation, Relatedness, Phylogeny

Prokaryotes & Eukaryotes b Two main types of cell types based on differences in size, structure and other characteristics b Fossil evidence • • • Prokaryotic cells – 3. 5 billion years ago Eukaryotic cells – 1. 5 billion years ago Multicellular organisms – 700 million years ago

Hierarchy of Groups b Horse is more like a dog then a shark • Horses and dogs are mammals b Horse is more like a shark then an oyster • Vertebrates vs. invertebrates b Each kingdom is broken down into smaller groups called taxon (plural taxa) to assist with categorization b Kingdom is largest down to species

Hierarchy of Groups Plantae--includes all plants Magnoliophyta--flowering plants Magnoliopsida--dicots Magnoliidae--subclass for Magnolia-like plants Magnoliales--order for Magnolia-like plants Magnoliaceae--family for Magnolia-like plants Magnolia--genus includes all Magnolias grandiflora--specific epithet b b The name for a species consists of the genus name and the specific epithet. **Notice that the endings will always tell you what rank you are dealing with, even if you don't recognize the word. For example, the word "Sterculiaceae" could only refer to a family. As you go up, each category is made of groups of members of the category below it-e. g. , there are many types of Magnolia but they all fit into the genus Magnolia. The Magnolias and their relatives are all in the Magnoliaceae. Orders are made up of families, subclasses are made of orders, etc.

Binomial Nomenclature b Using two words for each species • Genus and species names used • Canis lupus (wolf); Canis latrans (coyote); Canis familiaris (domestic dog) b Common Names • Problematic because they are not standard – Mountain lion, puma and cougar – P. 395, fig. 11. 13

Origins of Diversity b Similar to others in your species but not exactly the same – Diversity between species begins within a species – Certain different characteristics found between two populations in response to their environment may allow new species to develop • First described in 1859 by Charles Darwin in his book: On the Origin of Species by Means of Natural Selection

Genetic Variation b Changes in characteristics are produced by: 1. Random genetic mutations – Introduce variety – Especially important in asexual organisms 2. Selection for a particular characteristic that increases the organisms chance of survival and breeding in a particular environment

Determining Relatedness b Taxonomy involves evolution • A need to determine the evolutionary history of groups of organisms – Comparing different species living today with those that lived in the past b Ways by which scientists determine relatedness • Anatomy, development, biochemistry, DNA

Evidence from Anatomy b Classification between major classes can be difficult • Archaeopteryx – 150 million years ago b Fossils not required to find anatomical evidence of evolution • Human arm, horse’s leg, bat’s wing and whale’s flipper • All specialized for what they do but they have the same evolutionary origin - homologous

Evidence from Anatomy

Further Evidence b Development • Relatedness due to appearance can be a dangerous mistake – Larval and adult forms of organisms can be very different and they are the same species!

Further Evidence b Biochemistry • Comparisons due the molecules from which organisms are made • Comparisons of proteins and hormones – Horseshoe crab is more similar to spiders then to other crabs

Further Evidence b DNA • Genes consist of sequences of nucleotide bases in a segment of DNA • Human single strands of DNA are compared to other organisms and the amount of complementary base pairing that occurs indicates relatedness – 93% match with the macaque monkey – 98% match with the chimpanzee • DNA can also help to determine how long ago species began to diverge from a common ancestor – Mitochondrial DNA – mother to offspring – It mutates at a predictable rate so it provides a molecular clock for measuring rates of evolution

Phylogeny b “True” evolutionary history of groups of organisms b Common ancestors share characteristics of all organisms that come after in a phylogenetic tree b Smaller differences help to distinguish genus’ from each other

Phylogeny b Order Artiocactyla • Even number of hoofed toes on hindfoot; specialized teeth and digestive systems for vegetation b b Family Bovidae – horns Family Cervidae – antlers • Genus Cervus – highly branched antlers • Genus Rangifer – broad, palmate antlers (hand shaped)

Phylogenetic Tree