MARIETTA BIOL 222 - Intro to Vertebrates/Evolution - The Basics (12 pages)

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Intro to Vertebrates/Evolution - The Basics



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Intro to Vertebrates/Evolution - The Basics

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Pages:
12
School:
Marietta College
Course:
Biol 222 - Vertebrate Zoology
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Evolution Basics Lecture Outline Page 1 of 12 Based on Pough et al 1989 Vertebrate Zoology 3rd Ed MacMillan Hickman et al 2001 Integrated Principles of Zoology 11th Ed William C Brown Publishers Biology 222 Vertebrate Zoology Intro to Vertebrates Evolution The Basics Theme The turtle as a typical vertebrate Demonstration Turtle Question what is a vertebrate characteristics size from 0 1 gram to 100 000 kg length to 60m all habitats all types of feeding strategies presence of a vertebral column and associated brain spinal cord etc 50 000 extant species up to 500 000 extinct species Some examples of vertebrates Myxini hagfish Cephalaspidomorphi lampreys 50 species with myxinoidea Elasmobranchii sharks skates rays 800 species Holocephali ratfish Cladista bichers reed fish Chondrostei sturgeon paddlefish Neopterygii gar bowfin Teleostei other ray finned fishes 21 000 species of fish Actinistia coelocanth 1 species Dipnoi lungfish 6 species Microsauria Caudata salamanders caecilians 350 species Temnospondyli Anura frogs and toads 3 500 species Testudomorpha Testudines turtles 225 species Lepidosauria tuatara lizards snakes 5 800 species Archosauria crocodiles 21 species crocs Aves birds 9 000 birds Synapsida mammals 4 000 species 17 groups 1EVOL01222 doc January 4 2001 Biology 222 Vertebrate Zoology 1EVOL01222 doc Evolution Basics Lecture Outline Page 2 of 12 January 4 2001 Biology 222 Vertebrate Zoology Evolution Basics Lecture Outline Page 3 of 12 Classification of the turtle Kingdom Animalia Plantae Fungi Protista Monera Phylum Chordata Class Anapsida Order Testudomorpha Family Emydidae Genus Terrapene box turtles species carolina eastern box turtle Terrapene carolina Linnaeus 1758 Note forms of order names family names proper handling of specific epithet including author Graptemys geographica Le Seur 1827 Note common names 1EVOL01222 doc January 4 2001 Biology 222 Vertebrate Zoology Evolution Basics Lecture Outline Go to Board Page 4 of 12 Taxa any hierarchical grouping a level Basic taxonomy Holotype part of species description must be deposited in museum must be mentioned in text is the basis for future assignment of the name paratype additional specimens representing the known variation of the species priority first description is the valid one each species must have unique specific epithet Commission of Zoological Nomenclature Evolution gene basic unit of selection DNA code for protein AKA locus allele differing form of gene same protein slightly different genotype all the genes of an individual Haploid only one allele for each gene sex cell diploid two alleles for each gene somatic cell Homozygous both alleles for a given locus are identical diploid cell Heterozygous two different alleles at a given locus phenotype the resulting traits structural behavioral etc of a given genotype Variation mutations are changes in the genetic code they give rise to new alleles alleles are combined into new genotypes and phenotypes through sexual reproduction and recombination Variation is the basis for evolution 1EVOL01222 doc January 4 2001 Biology 222 Vertebrate Zoology Evolution Basics Lecture Outline Page 5 of 12 1 There are differences in organisms evidence gathered on Beagle 2 3 There is a struggle for existence Malthus In the struggle certain differences will give those organisms possessing them an advantage Darwin s contribution These organisms will survive and reproduce in greater numbers differential reproduction 4 5 Over long periods of time Lyell the whole species will change evolution heritability any variation must exist in the genes be heritable if natural selection is to act on it Natural Selection differential reproduction of differing alleles genotypes phenotypes different levels selection of individuals and associated genes genic selection alleles going into sex cells group or interdemic selection species selection controversial Types of natural selection use bell drawings directional selection stabilizing selection driving force of allopatric speciation disruptive selection driving force of sympatric speciation 1EVOL01222 doc January 4 2001 Biology 222 Vertebrate Zoology 1EVOL01222 doc Evolution Basics Lecture Outline Page 6 of 12 January 4 2001 Biology 222 Vertebrate Zoology Evolution Basics Lecture Outline Page 7 of 12 Fitness measure of the reproductive success of an allele or individual Inclusive fitness fitness gained by the copies of your genes carried by relative s kin sometimes one can maximize his own fitness by foregoing reproduction to help kin rear offspring altruistic behavior 1EVOL01222 doc January 4 2001 Biology 222 Vertebrate Zoology Evolution Basics Lecture Outline Page 8 of 12 Types of variation 1 individual each individual has a unique assortment of genes genotype and thus a unique phenotype 2 polymorphism several discrete phenotypes exist in a population 3 sexual dimorphism a type of polymorphism where the phenotypes vary according to sex Often reinforced by sexual selection 4 geographic variation in populations according to geographic location polytypic a species with geographic variants pronounced enough to be subspecies monotypic a species which shows little variation over its range Speciation speciation the separation of a population into distinct breeding groups via natural selection and other genetic processes including chance biological species groups of actually or potentially interbreeding natural populations which are reproductively genetically isolated from other such groups gene flow the mixing of alleles in a population through breeding if effective gene flow exists then speciation cannot occur reproductive isolating mechanisms keep organisms of different species interbreeding 1 2 premating a b c d postmating a b c d 1EVOL01222 doc from habitat isolation temporal isolation behavioral isolation mechanical isolation gametic isolation zygote mortality hybrid sterility fitness of offspring January 4 2001 Biology 222 Vertebrate Zoology Evolution Basics Lecture Outline Page 9 of 12 effects of size if a population is large becomes subdivided strong but different natural selection on each pocket speciation assuming low gene flow if a population is small genetic drift speciation assuming low gene flow genetic drift the tendency for random chance to change allelic frequencies within a population pronounced in small populations effective population size the current population size may not be critical in the species evolution Often low population


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