BIO 203 1st Edition Lecture 13 Outline of Last Lecture I 3 Features Define and Animal s Body Plan A The number of tissue types in embryos B The type of body symmetry C The way in which the earliest events of embryo development proceed II About Fungi III Characteristics of Fungi IV Chytridiomycota V Zygomycota VI Glomeromycota VII Basidiomycota VIII Ascomycota Outline of Current Lecture I Cost of sexual reproduction II Red Queen hypothesis for the maintenance of sex III Advantages Asexual vs Sexual Reproduction IV Disadvantages Asexual vs Sexual Reproduction V Types of Asexual Reproduction VI Sexual Reproduction Current Lecture I II III Cost of sexual reproduction a Sex results in recombination good for populations potentially bad for individuals Very advantageous combinations of genes in the parent may get split up in the offspring b Sex requires extra energy expenditure finding a mate can be costly and risky Red Queen hypothesis for the maintenance of sex a Proposed by Van Valen in 1973 b In Alice in Wonderland Alice runs as fast as she can to stay in the same place c The analogy to nature is that organisms evolve as fast as they can just to keep pace with their co evolving competitors parasites predators and pathogens d Evolution requires genetic variation which can arise through sexual recombination Advantages Asexual vs Sexual reproduction 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 IV V VI a Sexual i Generates novel gene combinations ii Advantage in the face of antagonistic biotic interactions competition predation parasitism iii It reduces the expression of potentially harmful genes b Asexual i Fast Simple mitotic nuclear division followed by cytokinesis Meiosis takes time ii All cells can reproduce iii Favorable gene combinations are maintained Disadvantages Asexual vs Sexual Reproduction a Sexual i The production of males is a cost to the rate of reproduction relative to rates by asexual populations ii Recombination breaks up favorable gene combinations iii Male and female gametes must be brought into contact b Asexual i In a changing environment adaptation is severely restricted by asexual reproduction ii Risk of extinction by biotic interactions Types of Asexual Reproduction a Mitotic Parthenogenesis apomixes reproduction by single cells that are derived by mitosis i Offspring are clones ii Parthenogenesis is widespread among animals iii Obligate parthenogenesis only asexual reproduction is found in the bdelloid rotifers and darwinulid ostracods b Fission or Vegetative reproduction reproduction by detachment and subsequent differentiation of groups of mitotically derived cells or tissues i Production of offspring without recombination of genetic material ii Takes place by subdividing an existing body into 2 or more multicellular parts budding or fission c Incomplete fission can give rise to colonial organisms Sexual Reproduction a Reproductive processes in which the recombination of genetic material derived from more than one parent is possible b In animals sexual reproduction always involves meiosis and the formation of a gametes c Sexual reproduction with fertilization processes of reproduction in which meiotically derived haploid eggs and sperm fuse to create a diploid zygote d Gonochorism dioecy sexes are separated and individuals are either exclusively male or female e Hermaphroditism Both reproductive tissues in an individual