Download Chapter 16: Evolution, Final Exam Study Guide | PLB 105 and more Study notes Plant Taxonomy and Evolution in PDF only on Docsity! Ch 16: Evolution “The Inheritance of Acquired Characteristics” ‐ Ex: A giraffe long neck, stretched higher and higher over time ‐ Acquired traits passed on over time Puzzle of Life’s Diversity ‐ Variety of living things called biological diversity ‐ How are they related? They EVOLVED “Nothing in Biology makes sense except in the Light of Evolution” ‐ Theodosius Dobzhnsky Evolution (or change over time) is the process by which modern organisms have descended from ancient organisms. Evolution is change in allele frequency over time. ‐ Allele: alternate forms of a gene Natural Selection ‐ Primary driving force in evolution (changing allele frequency) ‐ Struggle for existence – resources are limiting ‐ FITNESS IS ALL THAT MATTERS Charles Darwin ‐ Theory of evolution based on his observations while voyaging on HMS Beagle ‐ Tried to explain similarities between animals and plants of arid Galapagos Islands and humid South American mainland Patterns of Diversity ‐ Well suited to environment ‐ Many ways organisms survive and reproduce ‐ Similar areas on different continents were inhabited by very different animals Thomas Malthus ‐ Population growth would quickly over run the earth ‐ Why don’t maple trees cover the earth since they each release 1000s of seeds? ‐ Darwin asked: “what causes the deaths of so many?” “Reproductive factors, why some survive compared to others” Adaptations: Any trait that increases fitness ‐ Allows organisms to adapt Darwin’s Premises of Evolution by Natural Selection 1. Overproduction: a. Each species produces more offspring than will survive to maternity 2. Inherited variation a. Individuals in a population exhibit inheritable variation in their traits 3. Limits on population growth: a. Organisms compete for life essentials 4. Differential reproductive success: a. Most favorable characteristics will survive/get passed on Natural Selection ‐ Results from NO human intervention, control, or direction ‐ Increases species fitness over time ‐ Results in the inherited characteristics of a population Sexual Selection ‐ Mate Choice: Maximize reproductive potential o Strength o Territory o Ornamental o ECT… Evolution is poorly understood ‐ Many Americans do not believe in evolution ‐ True of False: Human beings, as we know them, developed from earlier species ‐ Has never been observed Evolution Evidence ‐ Galapagos Finches ‐ Fossils o Provide a record or earlier plants and animals o Where and when organisms lived o Idea of lifestyles ‐ Geological formations ‐ Isotope/Carbon dating ‐ Geographic distribution of living species ‐ Homologous body structures ‐ Similarities in early development Population Genetics ‐ How evolution occurs ‐ Evolution: Change in gene frequencies through time ‐ Tracts the fate, across generations Hardy‐Weinberg Principle ‐ Mathematical prediction that allele and genotype frequencies do not change from generation to generation ‐ When in H‐W equilibrium, no change in gene frequencies, no evolution of the population ‐ H‐W Law: o p2+2pq+q2=1 & p + q = 1 p = dominate allele frequency q = recessive allele frequency p2 = % of homozygous dominate q2 = % of homozygous recessive 2pq = % of heterozygous o Assumptions No Natural Selection No Mutation No Migration All individuals contribute equally Mating occurs at random o Useful? Provides explicit statements about processes under simple conditions Facilitates further development of models Microevolution ‐ Mutation (alteration in a cell’s genetic material) is the source of new alleles in a gene pool ‐ Allele or genotype frequencies may be changed by mutation, genetic drift, gene flow, or natural selection Founder Effect ‐ Variation of genetic drift ‐ When small number of individuals from one population found a new population that is reproductively isolated from the original one. Biological Species Concept ‐ Problems o Applies only to sexually reproducing organisms o Two widely separated populations of the same species don’t interbreed in nature o Organisms assigned to different species may interbreed in a greenhouse, zoo, aquarmium Reproductive Isolation ‐ Occurs o When two species reproduce at different times of day, season, year o Structural differences in the reproductive organs of species ‐ Reproductive failure o Occurs even when fertilization takes place between gametes of two species Key Terms: Gene Pool ‐ All the alleles of the genes in a freely interbreeding population Microevolution ‐ Small‐scale evolutionary changes caused by changes in allele or genotype frequencies in a population over a few generations Genetic Drift ‐ Random change in allele frequencies in a small breeding population o Island, isolated areas especially o Large Populations = Small Effects o Small Population = Large Effects Gene Flow ‐ Movement of alleles between local populations due to migration and subsequent interbreeding o Ex: Bottlenecking Allele frequency is altered due to population crash Biological Species Concept ‐ Concept that a species consists of one or more populations whose members can interbreed to produce fertile offspring and cannot interbreed with individuals of other species Reproductive Isolation ‐ Situation in which reproductive barriers prevent members of a species from successfully interbreeding with member of another species Allopatric Speciation ‐ Evolution of a new species that occurs when one population becomes geographically separated from the rest of the species and subsequently evolves Sympatric Speciation ‐ Evolution of a new species that occur within the parent species’ geographic region ‐ In plants, may occur as a result of allopolyploid in a interspecific hybrid Interspecific Hybrid ‐ Offspring of individuals of different species ‐ Usually dies at an early stage of embryonic development ‐ If it survives to adulthood, it usually cannot reproduce successfully Allopolyploidy ‐ Situation in which an interspecific hybrid contains two or more sets of chromosomes from each of the parent species ‐ May enable to interspecific hybrid to reproduce successfully as a new species Extinction ‐ Death of every member of a species Mass Extinction ‐ Extinction of many species during a relatively short period of geologic time Ch 18: The Classification of Plants and Other Organisms Age of Exploration / Importance ‐ 16th – 17th century ‐ Toured world and brought back new specimens to name ‐ Greatly expanded knowledge ‐ Darwin’s voyage led to theories on natural selection Scientific Names ‐ Biologists use scientific names to precisely ID organisms ‐ Each organisms has only one scientific name o Avoids confusion Binomial Nomenclature ‐ Species o The basic unit of classification ‐ Generic name (genus) – Specific epithet (species) Molecular Characters ‐ Enormous number of characters ‐ Different parts of the genome accumulate mutations at different rates – possible to examine relationships at different levels Tree of Life ‐ Planet Earth is about 4.6 billion y.o. ‐ Oldest known rocks are about 3.8 billion y.o. ‐ Oldest fossils (prokaryotes) are about 3.5 billion y.o. ‐ All living organisms on this planet share a common ancestor ‐ The tree of life reflects the branching pattern of speciation that has occurred since the origin of life. EXAM Q: The Three Domains Sheet ‐ Domain Bacteria ‐ Domain Archaea ‐ Domain Eukarya Key Terms: Taxonomy: ‐ Science of describing, naming, and classifying organisms Binomial Nomenclature ‐ System for giving each organism a two‐word scientific name ‐ First used consistently by Carolus Linnaeus Systematic ‐ Scientific study of the diversity of organisms and their natural (evolutionary) relationships ‐ A systematist seeks to reconstruct phylogeny Phylogeny ‐ Evolutionary history of a species or other taxonomic group Monophyletic ‐ Said of a group consisting of organisms that evolved from a common ancestor CH 22: Introduction to the Plant Kingdom – Bryophytes Colonization of Land ‐ Plants required evolution of structural physiological, reproductive adaptations ‐ Plants produce gametes in multicellular gametangia that contain a protective layer or sterile cells Plant Ancestors 1 ‐ Plants probably evolved from green algae ‐ Similar biochemical characteristics: o Pigments o Cell‐wall components (cellulose) o Carbohydrate storage material (starch) Plant Ancestors 2 ‐ Similar fundamental processes o Cell Division ‐ Land plants probably descended from charophytes (stoneworts) o Based on molecular and structural data Plants are all derived from green algae Alternation of Generations ‐ A type of life cycle characteristics of plants and a few algae and fungi ‐ They spend part of their life in a multicellular n gametophyte generation and part in a multicellular 2n sporophyte generation The Gametophyte Generation ‐ Produces haploid gametes by mitosis o Antheridium – produces sperm cell o Archegonium – produces an egg ‐ Fertilization: Gametes fuse to form a diploid zygote The Sporophyte Generation ‐ 1st stage: Zygote o Develops into an embryo, protected and nourished by gametophyte plant ‐ Mature sporophyte plant has spore mother cells that undergo meiosis to produce haploid spores o Which is the 1st stage in gametophyte generation Key Terms: Cuticle ‐ A noncellular, waxy covering over the epidermis of aerial plants helping to prevent water loss Stoma ‐ A small pore in the plant epidermis that allows gas exchange to occur; for photosynthesis Antheridium ‐ Multicellular male gametangium that produces sperm cells Archegonium ‐ A multicellular female gametangium that produces an egg Spore ‐ A reproductive cell that gives rise to individual offspring in plants, fungi, and certain algae and protozoa Moss ‐ A member of the phylum of spore‐producing nonvascular plant in which the dominant n gametophyte alternates with a 2n sporophyte that remains attached to the gametophyte Protonema ‐ In mosses, a filament of n cells that grows from a spore and develops into a leafy moss gametophytes Capsule ‐ Portion of the bryophyte sporophyte in which spores are produced Liverwort ‐ A member of a phylum of spore‐producing, nonvascular, thalloid or leafy plants whit a life cycle similar to that of mosses Thallus ‐ A body that lacks roots, stems, or leaves Gemma ‐ A small body of tissue that becomes detached from a parent liverwort and is capable of developing into a new organism Hornwort Classification ‐ Whisk ferns and horsetails were considered distinct enough to be classified in separate phyla ‐ DNA comparisons and similarities Life Cycle of Ferns 1 ‐ Fern founds bear sporangia in clusters (sori) o Meiosis in sporangia produces haploid spores ‐ Fern gametophyte (prothallus) develops from a haploid spore o Bears both archegonia and antheridia Life Cycle of Ferns 2 ‐ Each archegonium contains a single, nonmotile egg; each antheridium produces numerous sperm cells ‐ Following fertilization, diploid zygote grows by mitosis into a multicellular embryo (immature sporophyte) 3 Groups of Lycophytes ‐ Spike Moss Sporophyte o Long, creeping rhizomes that typically branch dichotomously o Roots that branch dichotomously o Overlapping, scale‐like 3 Groups of Lycophytes ‐ Club Moss sporophyte o True roots o Rhizomes and erect or trailing aerial stems o Small, scalelike microphylls ‐ Spike Moss sporophyte o Long, creeping rhizomes that typically branch dichotomously o Roots that branch dichotomously o Overlapping, scalelike microphylls ‐ Quillwort o Underground corm o Cylindrical, quill‐like microphylls o Roots Among the seedless plants: ‐ Mostly homosporous ‐ Spike mosses and quillworts (both Lycophytes) Ecology and Economics 1 ‐ Ferns and lycophytes help form soil, prevent erosion o Branching underground rhizomes and roots or rhizoids hold soil in place ‐ Living species of limited economic importance o Many cultivated for aesthetic appeal Ecology and Economics 2 ‐ Coal deposits o Formed from remains of ancient ferns, club mosses, horsetails o Powered Industrial Revolution of 19th century, used today to produce electricity Key Terms: Xylem ‐ Vascular tissue that conducts water and dissolved minerals Phloem ‐ Vascular tissue that conducts dissolved sugar and other organic compounds Microphyll ‐ Type of leaf found in lycophytes ‐ Contains one vascular strand Megaphyll ‐ Type of leaf found in virtually all vascular plants except lycophytes ‐ Contains multiple vascular strands Ferns ‐ Phylum of seedless vascular plants that reproduce by spores produced in sporangia ‐ Undergoes alternation of generations between dominant sporophyte and gametophye ‐ Largest, most diverse group of seedless vascular plants ‐ Whisk ferns and horsetails classififed as ferns Lycophytes ‐ Phylum of seedless vascular plants, some of which are heterosporous ‐ Lycophytes included club mosses, spike mosses, quillworts Homospory ‐ Production of one type of n spore that gives rise to a bisexual gametophyte Heterospory ‐ Production of two types of n spores, microspores and megaspores ‐ Found in spike mosses, quillworts and some ferns ‐ Ch 24: Gymnosperms ‐ “naked seed” ‐ Conifers are largest division ‐ Characterized by: a. Thick cuticle b. Recessed stomata c. Long, thin leaves (needles) Spores: ‐ A spore is a single cell with a minimal food reserves to sustain the plant that develops from a germinating spore ‐ Seeds are reproductively superior spores Advantages of heterospory ‐ Ancestor of gymnosperms was heterosporous ‐ Evolution of heterospory… ‐ Female gametophyte greatly reduced in size, so much so that it could be enclosed and protected within ‐ Male gametophyte (n) is dispersed in seed plants, but is protected by a layer of sporophyte tissue (2n) ‐ The whole structure is called a pollen grain Advantages of seeds ‐ Protection ‐ Nourishment ‐ Dormancy: can germinate when conditions are good/ideal ‐ Dispersal: The seed coat can be modified for dispersal ‐ Angiosperm seeds are enclosed in a bribe (fruit) and animals move them 4 Phyla of Gymnosperms 1. Conifer a. Woody trees and shrubs with needlelike, mostly evergreen leaves, and seeds in cones 2. Cycads a. Palmlike or fernlike in appearance b. Pollen and seeds in conelike structures c. Relatively few living members 3. Ginkgoes a. Ginkgo biloba, only surviving species in phylum b. A deciduous tree c. Female ginkgoes produce fleshy seeds directly on branches 4. Gnetophytes a. Share traits with angiosperms b. More efficient water‐conducting cells (vessel elements) in xylem