BIOL 112 1st Edition Lecture 8 Outline of Last Lecture I Condition 2 No Mutations II Condition 3 No Emigration or Immigration III Condition 4 Reproductive Success IV Mathematical Models of Natural Selection V Different Types of Selection VI Allopatric Speciation VII Physical Isolation Leads to Genetic Isolation Outline of Current Lecture VIII Observed Speciation IX Questions X Shift in Host Availability XI Divergence of Fly Populations XII Speciation in Action XIII Classification and Diversity XIV Naming Organisms XV Carl von Linn XVI Systema Naturae XVII Binominal System of Nomenclature XVIII Genus Name XIX Specific Epithet Descriptor XX Proper Use of Binominal XXI What is a Species XXII Ways of Defining XXIII Larger Linnaean Categories Current Lecture I Observed Speciation Has anyone seen a species emerge Several cases documented of the generation of genetically isolated populations species in the laboratory But also a number of examples of what appears to be speciation in action in field populations Documented Therio example of speciation with intermediate types in fossil record These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute S yellowstonensis descendent from S niagarae Centric diatom alga found only in Lake Yellowstone Diatom species defined by details of silica cell wall structures Apparent directional selection is to produce new species Extremely rapid evolution of an organism speciation in about 3 000 to 4 000 years followed by no subsequent change Rapid speciation perhaps driven by rapid climactic shift at the end of the Ice Age II Questions Why speciation only in Lake Yellowstone and not adjacent lakes Did climactic shift drive rapid speciation How What selective pressures Does this apply to other diatoms protists Another Example Rhagoletis Pomonella Railroad worm or apple maggot Parasitic fly native to N America Lays eggs on fruit of hawthorn tree Maggots eat fruit pupate over winter and emerge as adult flies to mate and lay eggs on new fruit Timing of mating and egg laying depends on time tree sets fruits III Shift in Host Availability Apples and other domestic fruit trees imported to N America and planted during expansion European settlements in late 18th early 19th Century Apple Malus domesticus not a native North American species Johnny Appleseed John Chapman 1774 1845 went around selling Apple trees By mid 19th Century observers noticed that the these maggots Rhagoletis were infesting apples which had not happened before IV Divergence of Fly Populations Two different population of flies races now identified Those attacking the hawthorns Those attacking the apples Hawthorn population does not infest apples apple population does not infest hawthorns Timing of mating egg laying and life span of larval stage are all coordinated to specific tree host species and are very different V Speciation in action Two populations are distinct in behavior genetic content and life cycle Blooming and fruiting times of apples and hawthorns are very different Fly populations have shifted their mating egg laying timing to match host tree species Populations differ at several genetic loci Little hybridization perhaps as little as 4 6 genetic exchange between two populations very little gene flow Two populations could be in the process of becoming genetically isolated which is in the definition of speciation Systematics Taxonomy Chapters 25 26 VI Classification and Diversity Categorize living things into groups but why do we need to do this Uses for systematics Aids understanding of structures and functions of components and organs Aids understanding of evolution and family tree of organisms good systematics should reflect evolutionary history Aids rapid identification of relatives of previously unknown organisms Provides a framework to learn and remember different types of organisms Taxonomy science of naming organisms and groups of organisms one part of the larger activity which is systematics Systematics science of developing and evaluating classification schemes VII Naming Organisms Frog Leopard Frog used in the North Grass Frog in other parts of the country Use of common names gives problems Language differences Different regional names We can solve this by giving this particular creature an unambiguous scientifically significant name Older Approach Elaborate Descriptions Long descriptions in Latin Example Honeybee Apis pubescens thorace subgriseo abdomine fusco pedibus posticis glabris utrinque margine ciliatis Unwieldy system and too many words obviously Needed innovation and reform VIII Carl von Linn 1707 1778 Carolus Linnaeus latinized version of name Son of Swedish clergyman grew up poor was thought to be stupid because he was more interested in natural sciences than in the standard curriculum latin greek nearly apprenticed to be a shoemaker 1728 went to University of Uppsala sweden for medical training Showed outstanding promise and was giving lectures on botany while still a sophomore 1732 sent by Academy of Sciences of Uppsala on collecting expedition to Lapland unexplored territory by the arctic circle In 6 months he covered 1 200 miles on foot and by horse collecting botanical geological and anthropological information about country and people Lap people S mi 1735 received M D from University of Hardewyk Holland 1735 Major scientific contribution first published Systema Naturae First edition was 12 pgs so more like a pamphlet The 10th Edition 1758 is regarded as definitive nearly 1 400 pgs 1741 appointed Professor of Botany at University of Uppsala scientific work won him world wide reputation 1761 granted title of nobility by Swedish crown allowed the addition of the von to his name IX Systema Naturae Organized all plants animals and rocks into hierarchical scheme of nested categories Tenth Edition 1758 is regarded as most developed definitive version Established major innovations to the science of systematics basic set of rules for organization and naming still used today His books were originally kept away from students because it was regarded as pornographic because of focus upon sexual life cycles as important identification characters Linnaean Innovations Linnaean system of classification what we see today as systematics Brevity of writing style Development of and focus upon concept of species as fundamental biological unity X Binominal System of Nomenclature