Detail of topics included in pb295E, 'Topics in Plant Evolution'

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PB295E, Topics in Plant Evolution, emphasizes evolution and evolutionary mechanisms in Angiosperms. Because Paleobotany and Systematics courses are already offered at NCSU, PB295E emphasizes areas not usually contained in those two approaches to the study of Evolution in plants.
The course will involve 2 class meetings per week, reading assignments and two exams. Pertinent videos will be shown during class meetings.

Assignments will include readings from a Course Pac of selected articles and the book, Plant Variation and Evolution by D. Briggs and S. M. Walters, Cambridge Univ. Press.

Detail of TOPICS included in PB295E, 'Topics in Plant Evolution':
(1) What is Evolution?

Darwin's Theory of Natural Selection

Darwin's dilemma

Modern synthesis

Evidences of evolution (a) Artificial Selective Breeding (b) Comparative Anatomy

(c) Fossil Evidence (d) Molecular (DNA) and (e) Developmental Biology

Tempos of evolution: (a) Gradualism (b) Punctuated Equilibrium
(2) Plant - Green Algae Connection:

Plate Tectonics

Early Earth

Character indicators of algal/plant common ancestry

Proposed mechanism for the Evolution of the Algal Zygotic meiosis life cycle to the

Plant Sporic meiosis life cycle

(3) Sources of the Variation necessary for evolution to occur and how a species' variation potential is a function of its Breeding System:

Sources of the Variation: (a) Mutations (b) New sexual recombinations

(c) Introgression

Breeding Systems: (a) Out-crossing (b) Selfing and (c) Apomixis (vegetative &


Adaptations promoting/preventing (a) and (b) above {(1) self-incompatibility genes

(Gametophytic and Sporophytic) (2) Heterostyly (3) Gynodioecy (4) Temporal

(4) Types of Variation and the type that fuels evolution:

Genetic vs. Environmental variation {Turesson, Clausen, Keck and Hiesey} -

Common Garden Experiments

Ecotype concept and Challenge to Ecotype concept i.e., Clines

Methods of studying presence/absence/degree of genetic variation in plant

populations: (a) Isozymes (b) Chromatography (c) RFLP (d) RAPD (e) DNA

Sequencing (chloroplast, mitochondria and nuclear)

(5) Hardy-Weinberg Equilibrium:

Population Genetics definition of Evolution

Hardy-Weinberg Equilibrium - (a) the criteria necessary for no evolution to occur

in a population (b) Derivation of H-W Equilibrium equation,

Sample case studies illustrating usefulness of H-W

(6) Deviations from Hardy-Weinberg i.e., why evolution DOES occur in natural populations:

Case Studies of real plant populations illustrating reality of (a) mutations (b) gene

flow (c) non-random mating (d) chance events {Genetic drift e.g., founder

effects, bottlenecks} (e) natural selection {examples of stabilizing selection,

directional selection, disruptive selection}

(7) Species and Speciation:

Species (a) definitions (b) The Species Problem (c) Incipient species

(d) Species delimitation

Speciation modes - Allopatric, Sympatric

Examples of Pre and Post Zygotic isolating mechanisms in plants: (a) Temporal Isolation (b) Floral Isolation (c) Mechanical Isolation (d) Ecological Isolation

Results of isolating Mechanisms

Case Studies of Allopatric Speciation in Plants including Adaptive Radiation

(8) Hybridization:

Hybridization - definition

Hybridization in nature: (a) Role of habitat disturbance (both nature and man caused)

in hybridization (b) Hybrid Zones (c) Hybrid Swarms (d) Are all hybrids new

species? (e) Views on hybrid origins

Examples of Various Possible Consequences of Hybridization: (a) fully fertile

hybrid (b) semi-fertile hybrid (c) asexually reproducing sterile hybrid (d)

polyploidy (e) hybrid inviability

Introgression - (a) definition (b) methods of detection (c) evolutionary


Two detailed case studies - Natural Hybridization and Introgression in the Louisiana


(9) Polyploidy:

Polyploidy - (a) frequency in plants? (b) base numbers (c) ancient

polyploid series

Polyploid Detection Studies (a) Karyotypes (b) Isozymes (c) Chromatography

(d) Nuclear DNA content (e) Colchicine

Polyploidy Types - Allopolyploidy, Autopolyploidy, Segmental Polyploidy

Case studies of polyploidy including Tragopogon, and Triticum turgidum (bread


Polyploid Origins - 2 mechanisms (a) Somatic Doubling (b) Unreduced Gametes

Mechanisms of Meiotic Dysfunction

Persistence of Polyploids

(10) Flower and Fruit Evolution:

Appearance of Angiosperms

Plate Tectonics - continent positions at time of Angiosperm Appearance

Angiosperm Ancestry

Unique Angiosperm Characteristics

Old and New views of characteristics of earliest flower

Evolutionary Trends of Flowers - (a) ovary position (b) floral symmetry

Agents of floral evolution - pollinators

Evolution of floral characters in response to selective pressure of attracting

pollinators: (a) pigments (Carotenoids, Flavonoids, and Betacyanins) (b) flower

shape (c) fragrances (d) floral markings, (e) nectar production

Evolution of fruit characters in relation to the selective pressure of promoting fruit

dispersal: (a) wind, (b) water (c) self projected and (d) animal dispersed fruit


(11) Evolution of Secondary Metabolites - Evolution of chemical compounds in response to the selective pressures of herbivores and pathogens

Alkaloids - examples of plants having evolved (a) Morphine (b) Cocaine (c) Nicotine

(d) Caffeine

Terpenoids - examples of plants having evolved (a) Isoprene (b) Essential oils

(c) Rubber (d) Cardiac Glycosides

Phenolics - examples of plants having evolved (a) Tannins (b) Salicylic Acid

(c) Lignins

(12) Detailed Examination of Several Case Studies of Co-evolution - identifying the selective pressures exerted by both participants

Dodo bird and Sideroxylon grandiflorum tree on Mauritius- fruit and fruit disperser - FACT or FALACY - a controversy

Ants and Acacia trees in Central America

Mistletoe and the Mistletoe birds in Australia

Yucca plants and the Yucca moth in USA

Sycamore Fig and Fig Wasps in Africa

Goldenrod and the Gallfly in USA

(13) ABC Model of Flower Development - Genetics of Floral Evolution

Model research organism - Arabidopsis thaliana

Stages in floral development

Developmental fields of Gene Expression

5 genes specifying floral organ identity in Arabidopsis

Loss of gene function: (a) Loss of A function (b) loss of B function (c) loss of

C function

LEAFY gene and mutation of LEAFY

E function genes

Unanswered questions

(14) Evolution instigated by man's activities

Heavy metal pollution and evolution of resistant plants

Evolution for herbicide resistance in crop plants

Genetically modified organisms

Habitat disturbance favoring evolution by hybridization

Alien Introductions and evolution by hybridization/ introgression

(15) Evolutionary Stasis:

Three case studies: (a) Wollemi pine (b) Ginkgo biloba (c) Metasequoia

Characteristics associated with evolutionary stasis within a plant group

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