BOTANY 400 - Lecture Exam 2

Thomas Burnet

• 1681

• Typical Pre-18th Century View of Earth, its Changes, & Truth

• Wrote The Theory of the Earth

• Believed finding the Truths of the Natural World was respecting God’s Truth

Jean Baptiste Lamarck

• 1744 to 1829

• Author of Zologische Philosophie

• Early Evolutionary Thought of “Ladder Thinking”

• Used a Scalae Naturae or Ladder Model

• Eventually used a Tree Model

Lamarck’s Ladder

• Continuum between Physical & Biological World

• Transmutation: Life progresses Upward due to Internal Drive towards Perfection

• Current Primitive Organisms due to Constant Spontaneous Generation of New Life

• Inheritance of Acquired Characters leads to Change

• Hierarchy of Fourteen Levels

Georges Cuvier

• Critic of Jean Lamarck

• Argued there is No One Linear Ladder

• Led to Creation of Lamarck’s Tree

Lamarck’s Tree

• Two Lines of Spontaneous Generation with Subsequent Branching

• Branching as Fundamental Pattern of Evolution in 1815

• Some Odd Branches connecting Very Different Groups of Animals

Robert Chambers

• 1844

• Author of Vestiges

  • Only Pre-Darwin “Evolution” Book in English in 1840s & 1850s

• Began setting Acceptance of Evolution & Origin of Species

• Denied Special Creation for Each Species

  • Received Criticism from Biblical Scholar Bosanquet

Charles Darwin

• 1859

• Formulation of Evolutionary Theory

• Refers to Evolution as “Descent with Modification”

• Used Tree-Thinking

• Author of Origin of Species 1859

The Three Main Claims of Darwinian Evolution

• Descent: Living Species are Related by Common Ancestry

• Change through Time occurs not at the Organism Level but at the Population Level

• Modification: Main Cause of Adaptive Evolution is Natural Selection

Definition of Evolution

• Change of Genetic Materials

  • Genotype: DNA, Genes, Chromosomes, Genomes

• Change in Genotype leading to Change in Physical Attributes

  • Phenotype: Morphology & Physiology

• Occurs within & among Populations of Species through Time & Space

Evidence for Evolution

• Classification & Hierarchical Distribution of Traits

• Homology & Vestigial Structures

• Fossil Record & Biogeography

• Variation Among Populations & Speciation

• Agreement between Gene Trees

Hierarchical Classification

• Evidence of Evolution

• Species within Groups appear more similar than they do to Other Groups

• Shared Morphological Features amongst Group

• More likely that Traits evolved Once in Common Ancestor

  • Characters as “Fossil” Footprints

• Distribution of Characters can be Explained by Trees

• Clades are Nested within Larger Clades

• Same Genes in Same Places in Genomes of Species with Common Ancestor

Clades

Monophyletic Groups defined by Shared Characteristics

Homology

• Evidence of Evolution

• Modification of Shared Character

• Derived from Same Structure, but Diverged to Match Niche

• Shown through EvoDevo Studies

Convergence

Phenomena of Unrelated Species in Very Similar Niches having Similarities in Morphology or Other Characters

Darwin’s Orchids

Group of Flowers that all possess Basic Homologous Floral Parts but are Highly Modified for Specific Pollinators

EvoDevo

• Provides Genetic Basis for Basic Features

• Reveals Modification of Homologous Genes

• ABC Model of Angiosperms

  • Only a Few Gene Differences involved in Very Different Looking Flowers

  • Transcription Factors Important

Vestigial Structures

• Homologous Parts with No Known Function

• Found in Highly Diverged Species in Different Niches

• Examples: Pelvic Girdle in Whales & Non-Functional Chloroplasts in Parasitic Dodder Plants

Fossil Record

• Evidence of Evolution

• Missing Links as Transitional Forms

• Rich & Consistent with Information from Hierarchical Relationships based on Morphology & DNA

• Archaefructus in Plants

Archaefructus

Plant Fossil consistent in Terms of Age & Morphology with Basal Angiosperms

Missing Links

• “Transitional” Forms

• Not Truly Intermediate

• Each Descendant Species is Own Tip with its Own Derived Traits & Equal Time to Evolve/Diverge

Biogeography of Life

• Evidence of Evolution

  • Large Amount of Evidence

• Law of Representative Species

• Convergent Forms in Similar Environments on Different Continents

• Distribution of Extinct Organisms as Fossils provides First Evidence of Continental Drift

  • Similar/Closely Related Species found Across Continents that would’ve been Next to Each Other or Connected

Law of Representative Species

• Evidence of Evolution

• Part of Biogeography

• Closely Related Species replace Themselves across a Continent

• Ranges Neighbor Each Other but do Not Overlap

Direct Observation of Evolution

• Evidence of Evolution

• Documented Change due to Human/Artificial Selection

• Change within & among Populations due to Directional Selection

• Example: Origin of New Polypoid Species in Tragopogon

Pam & Doug Soltis

• Discovered Origin of New Polypoid Species in Last 150 Years

  • Occurred Multiple Times in Different Places

• Study the Genus Tragopogon

• Botanist Spotlight #4

Molecular Evolution

• Evidence of Evolution

• Fossil Footprint of DNA in Organisms

• Mitochondria, Nucleus, & Chloroplasts all Originally Bacteria absorbed by an Early Eukaryote

Genetic Variation within Species

• Required for Evolution

• Driven by Selection or Random Events

• Variation in Flowers, Pollinators, Light Regimes, Moisture Regimes, and Chromosome Numbers

• Substantial Amount within & among Populations

Natural Selection

Mechanism by which Populations are Modified in Response to their Environment

Adaptation

Adjustment in a Population to their Environment

Spring Beauty (Claytonia)

• Single Species

• High Variety in Flowers based on Different Environments

• Highest Variation in Number of Chromosomes in a Single Species

• Example of Genetic Variation within Species

Random Events

• One Driver of Evolution

• Gene Frequencies may fluctuate despite Natural Selection

• Caused by Random Sampling of Genes

• Genetic Drift & Founder Events

Study by Clausen, Hiesey, & Keck

• Studies on Variety of Plant Species during 1940s to 1950s

• Conducted by Three American Botanists in California

• Work on Achillea millefolium & Potentilla glandulosa Best Known

• Used reciprocal transplant design by setting up common garden site across elevation gradient.

  • Common Garden: Plants from different environments/gene pools grown in same garden.

  • Examines if phenotypical differences are genetic or environmental.

• Phenotypic plasticity in Achillea clinal genetic.

Common Garden Experiments

Plants from Different Environments/Gene Pools are grown in the Same Conditions to examine if Phenotypical Difference are Genetic or Environmental

Ecotypes

Genetic Variations adapted to Different Ecological Conditions

Cladogenesis

• Formation of New Species Lineages

• One Population branches to form New Species

• Darwin’s Descent

Anagenesis

• Evolution within a Species Lineage

• Species continues to diverge from Ancestral State

• Darwin’s Modification

Overview of Chemosystematics

• Use of Chemical Compounds to tell how Plants are Related

  • Pigments, Volatiles, Deterrents

• Type of Molecular Systematics

• Uses Secondary Compounds or Micromolecules instead of Macromolecules like DNA & Protein

Reasons for Chemosystematics

• Unequal Rates of Morphological Divergence in Different Lineages

  • Faboid & Mimisoid Legumes are Highly Modified but from Same Common Ancestor of Caesalpinoids

• Issues of Homology & Character Divergence vs. Analogy & Convergence

  • Independent Origin of Yellow Perianth in Marsh Marigolds & Buttercups

  • Independent Origin of Swollen & Green Barrel Stems in Cacti & Spurges

Plant Pigments

• Predominantly Green from Chlorophyll

  • Absorb Red & Blue Wavelengths while Reflecting Green & Some Yellow Wavelengths

  • Important in Systematics at Deepest Levels of Tree of Life

• Other Colors that contrast Green attract Animals

  • Aids in Pollination, Seed Dispersal, or Warning Coloration

• Types: Anthocyanins, Yellow Flavonoids, Colorless Flavonoids, Betalains, & Carotenoids

Challenges of Using Plant Pigments

• Often Unstable: Breakdown & Fade in Herbarium Specimens

• Environmental Variation: Effected by pH, Elevation, UV, Etc.

• Chemical Mimicry & Convergence

Flavonoids

• Usually Most Important Source of Non-Green Color in Plants

• Benzene Rings with Infinite Variety of Side Chains

• Important in Yellow, Blue, White, & “Black” Flowers

• Potentially have Health Benefits for Humans

• Absorb UV & Appear Dark to Insects

  • Guide Pollinators to Nectar

Anthocyanin Flavonoids

• Most Important & Widespread Group of Coloring Matter in Plants

• Found in Almost All Families of Angiosperms

• Replaced by Betalains in Most Members of Caryophyllales

  • Present instead of Betalains in Families Caryophyllaceae & Molluginaceae

Yellow Flavonoids

• 20+ Families in Distribution

• Give Yellow Colors to Flowers (In Part)

  • Also Found in Leaves but Masked

• Works with Yellow Carotenoids

  • Chemical Mimicry

  • Absorbs UV while Carotenoids reflect UV

  • Creates Bull’s Eye Pattern for Insect Pollinators

• Utility in Classification of Gesneriaceae

  • Present in Subfamily Gesneriopodeae in addition to Carotenoids

  • Absent in Subfamily Cytrandroideae which only has Carotenoids

Colorless Flavonoids

• Most Important Secondary Compound in Systematics

• Contributes to Body or Expression of Anthocyanins

• Strongly Absorbs UV

• Detectable with Gas/Gel/Paper Chromatography

  • 2D Spot Pattern is Specific for Each Type

• Used to prove Physalis lanceolata is Not a Hybrid between P. heterophylla & P. virginianum

  • Chromatography Pattern Not Additive

Betalains

• Named after the Beet Genus, Beta

• Nitrogen-Containing Pigments different from Flavonoids

• Absent in Plants with Anthocyanins

• Only Found in Families of Core Caryophyllales

  • Beets, Cacti, Pokeweeds, Amaranths

  • Absent from Families Caryophyllaceae & Molluginaceae which have Anthocyanins Instead

• 4 Parallel Origins discovered by Samuel Lopez-Nieves & Hiroshi Maeda in 2019

Betacyanins

Red & Violet Betalains

Betaxanthins

Yellow & Orange Betalains

Some Uses of Floral Pigments in Phylogenetics

• Classification of Salvia within Sage & Mint Family

• Evolution of Red Color correlated with Origin of Hummingbirds

  • All form One Clade

• Blue Flowers evolved for Bee Pollination

Overview of Volatile Compounds

• Often Restricted to Families, Genera, or Even Species

• Form the Taste of Plants

• Attract or Repulse Animals

• Used Consciously or Unconsciously in Classical Taxonomy

  • Conifers, Mints, & Carrots

  • “Sensual System” used by Linnaeus

Sensual System

• Artificial System of Classification

• Used by Linnaeus

• Based on Scent

• Aromatic, Fragrant, Musk-Like, Garlic-Like, Goat-Like, Foul, or Nauseating

Six Major Volatile Groups

• Terpenes: Pinenes, Menthol, & Catnip

• Aliphatic Oils: Magnolia & Amyl Acetate in Orchids

• Aromatics: Wintergreen

• Aminoid: Nitrogen Containing & Offensive, Found in Aristolochiaceae & Araceae

• Sulphides: Sulfur Containing, Found in Onions & Garlic

• Glucosinolates: Sulfur Containing, Found in Mustard

  • Chewing/Damage forms Isorhiocyanates

Mustard Oil

• Glucosinolates form Isothiocyanates as an Anti-Herbivore Defense

• Shared by 18 Different Looking Families

• Dalhgren believed Families Related and it Evolved Only Once or Twice

  • Denied by Cronquist

• DNA proved Two Evolutionary Origins

• 17 Families in Brassicales & 1 Family in Malpighiales

Caryophyllids (Order Caryophyllales)

• Member of Core Eudicots

• Order including Carnations, Cacti, & Chenopods

• 11,155 Species in 34 Families

  • 6% of Eudicot Diversity

  • Unusual Group that was Not Previously Thought to Form a Monophyletic/Natural Order

• Sister Clade to Asterids

• Arose about 110 to 100 Million Years Ago

Characteristics of Caryophyllids

• Usually Only have Perianth of Sepals

  • If Petals Present, they appear to be of Staminal Origin

• Often Live in Extreme Environments

  • Arid Regions, High Salt, & Low Water

• Often Weedy

• Adaptations: Succulence, Absent Leaves, Salt Excretion, and C4 & CAM Photosynthesis

• Specialized Photosynthesis: Convergently Evolved to Reduce Water Loss during Photosynthesis

  • Spatial Separation of Steps in C4

  • Temporal Separation of Steps in CAM

• Very High Diversity

Examples of Caryophyllids

• New Desert Families: Frankeniaceae, Simmondsiaceae, Tamaricaceae, Halophytaceae

• Halophytes: Salt Tolerant Plants like Glasswort

• Cushion Plants: High Latitude/Elevation Adapted Plants like Chickweed & Spring-Beauty

• Many of the Carnivorous Plants: Plants that Grow in Low Nitrogen Environments like Sundews & Asian Pitcher Plants (Nepenthes)

• Weeds: Tamarix & Baby’s Breath (Gypsophila)

Antarctic Pearlwort (Colobanthus quitensis)

• One of Two Flowering Plant Species in Antartica

  • Other is Hair Grass

• Grows on North Facing Slopes

• Cushion Plant in Order Caryophyllales

• Plant of the Day #4

Core Caryophyllales Characteristics

• Betalains: Nitrogen-Containing Pigments instead of Anthocyanin Flavonoids

  • Evolved Four Times within Group

• Centrospermae: Free-Central (or Basal) Placentation

• Produce Capsule Fruits

  • Pyxis: Capsule with Lid & Many Seeds Inside

  • Utricle: Capsule with Lid & One Seed Inside

• Difficult to Recognize/Classify Families

Family Caryophyllaceae (Carnations & Pinks)

• 2300 Species in 87 Genera

• Distributed through Temperate Regions of Northern Hemisphere

• Herbaceous & Often Weedy

• Dichasium Inflorescence

  • Usually Cyme with 3-Way Split & Oldest Flower in Middle

• Opposite Leaves with Swollen Nodes

• Urn-Shaped Capsule Fruit that Opens by Teeth or Valves

  • Often Surrounded by Calyx

• Family in Order Caryophyllales

Flowers of Caryophyllaceae

• 5-Merous Flower

• Unfused Corolla with Often Deeply Lobed Petals of Potentially Staminal Origin

• 1 to 2 Whorls of Anthers

• Syncarpic Pistil with 2 to 5 Carpels

• Free-Central or Axile Placentation

Floral Formula of Caryophyllaceae

CA5,(5) CO5 A5,10 G(2-5)

Examples of Caryophyllaceae

• Mouse-Ear Chickweed (Cerastium)

• Campions (Silene)

• Deptford Pink (Dianthus)

• Soapwort (Saponaria)

Family Amaranthaceae (Amaranths)

• 2050 Species in 174 Genera

• Herbaceous & Often Halophytes or Weeds

• Worldwide Distribution

• One-Seeded Utricle Capsule Fruit or Basal-Seeded Achene

• Family in Order Caryophyllales

Flowers of Amaranthaceae

• Small, Bracted, & Congested

• Corolla Absent

• Bisexual or Unisexual

  • Unisexual Plants Monoecious or Dioecious

• Superior & Syncarpic Pistil with 2 to 4 Carpels

Floral Formula of Amaranthaceae

CA5 CO0 A5 G(2-4)

Examples of Amaranthaceae

• Desert Specialists & Tumbleweeds: Saltbush (Altriplex) & Russian Thistle (Salsola)

• Native, Weedy, & Horticultural Species: Amaranth, Cottonseed, Winged Pigweed, Summer Cypress

Family Cactaceae (Cacti)

• 1400 Species in 100 Genera

• North & South American Distribution

  • One Taxon Dispersed in Africa

• Stem Succulents protected by Spines

• Often Epiphytes that Grow in Trees

• Leaves Absent except in Genera Pereskia & Rhodocactus

• Spines or Glochids at Areoles

• Berry Fruit that is Sometimes Semi-Dry

• High Diversity

• Family in Order Caryophyllales

Flowers of Cactaceae

• Epigynous Flower

• Hypanthium with Many Tepals & Stamens

• Inferior Syncarpic Pistil with 4 Carpels

• Parietal Placentation

Floral Formula of Cactaceae

P♾ A♾ ^-G^-(4)

Examples of Cactaceae

• Peyote (Lophophora)

• Queen of the Night (Selenicerius)

• Prickly-Pears (Opuntia)

Family Phytolaccaceae (Pokeweed)

• Small Family in Tropical & Temperate Regions

• Shrubs & Trees

• Raceme Inflorences

• Berry Fruits

  • Often Poisonous & Good Dyes

• Family in Order Caryophyllales

Flowers of Phytolaccaceae

• Five Small Petaloid Sepals

• Corolla Absent

• Twice as Many Stamens as Sepals

• Semi-Fused Carpels each with One Ovule

Floral Formula of Phytolaccaceae

CA5 CO0 A10 G(5+)

Examples of Phytolaccaceae

• American Pokeweed (Phytolacca americana)

• Indian Poke (Phytolacca acinos)

Family Polygonaceae (Smartweeds & Allies)

• 1100 Species in 61 Genera

• Herbs or Some Shrubs

• Wet OR Arid Regions

• Alternate & Simple Leaves at Swollen Nodes

• Ocrea: Stipules Modified into Sheath

• One-Seeded & Three-Angled Achene Fruit

• Non-Core Caryophyllid

• Family in Order Caryophyllales

Flowers of Polygonaceae

• Congested Flowers

• Basically 3-Merous

• Petaloid Tepals

• Superior Syncarpic Pistil with 3 Carpels

Floral Formula of Polygonaceae

P3+3or5 A1-3X G(3)

Examples of Polygonaceae

• Smartweeds (Persicaria)

• Docs (Rumex)

• Horticultural Taxa: Rhubarb (Rheum) & Buckwheat (Fagopyrum)

Ynés Mexía

• 1870 to 1938

• Mexican American with Dual Citizenship

• Joined Sierra Club after a Hard Time in Life

• Began Professionally Collecting Plants at 55 Years Old

• One of the First Female Botanists to Explore the Americas

• Collected Over 145,000 Plant Specimens in 13 Years

  • Collected 50 New Species

  • Many New Species Named in Honor of Her

• Died from Cancer

Rosids

• Part of Core Eudicots

• One of Two Very Large Groups of Eudicots

• Petals Generally Separate

• Usually More Stamens than Petals

• High Diversity

Order Saxifragales

• 2500 Species in 16 Families

• Sister Clade to Rosids

  • Diverged 120 Million Years Ago

• Identified by 2+ Separate or Semi-Fused Carpels

Other Families in Saxifragales

• Paeoniaceae: 33 Species in 1 Genus with Primitive Features, Hypogynous Flowers, and 5 to 8 Carpel

• Cercidiphyllaceae: 2 Species in 1 Genus of Small Trees with Unisexual & Wind-Pollinated Flowers

• Hamamelidaceae: 80 Species in 27 Genera of Trees & Shrubs with Inferior Ovaries & Woody Fruits

• Grossulariaceae: 150 Species in 1 Genus with Lobed Leaves, Raceme Inflorescences, Inferior Ovaries, and Fleshy Fruits

• (Potentially) Cynomoriaceae: Small Family of Holo-Parasites

Family Saxifragaceae (Saxifrages & Allies)

• 700 Species in 30 Genera

• Northern Hemisphere Distribution

• Herbs with Basal Leaves

• Prefer Wet Woods, Swampy Conditions, or Drippy Cliffs

• Family in Order Saxifragales

Flowers of Saxifragaceae

• 5-Merous & Perigynous Flowers

• Superior Syncarpic Pistil with 2 Carpels & Styles

• Hypanthium Often Present

Floral Formula of Saxifragaceae

CA5 CO5 A5or10 G(2)

Examples of Saxifragaceae

• Genus Micranthes

• Cool Wort (Sullivantia)

• Bishop’s Cap (Mitella)

• Prairie Alumroot (Heuchera)

Family Crassulaceae (Stonecrops & Jades)

• 1370 Species in 34 Genera

• Distributed in Warm Temperate Regions Worldwide

• Succulent Herbs or Some Small Shrubs

• Perform CAM Photosynthesis

• Follicle Fruits

• Major Radiation in Mediterranean Climates

• Family in Order Saxifragales

Flowers of Crassulaceae

• Mainly 5-Merous Flowers

  • Some 3, 4, or 6-Merous Species

• Twice as Many Stamens as Sepals

• Superior Apocarpic Pistil with usually 5 Carpel

  • Nectary Scales usually at Base of Each Carpel

Floral Formula of Crassulaceae

CA5 CO5 A10 G5

Examples of Crassulaceae

• Jade Plants

• Sedum

• Aeonium

• Rhodiola

• Echeveria

• Kalanchoe

Order Rosales

• Order in the Rosids

• Not Well-Defined Morphologically

• Includes Roses, Elms, Mariguana, Hops, Figs, Nettles, Etc.

• Nitrogen-Fixing via Actinomycetes

• Corolla Absent in Most Families

• Serrated & Sometimes Glandular Leaves

• Many Members with Unisexual & Wind-Pollinated Flowers

Family Rosaceae

• Almost 3000 Species in 100 Genera

• Worldwide Distribution but Most Common in North Temperate Regions

• Herbs, Shrubs, and Trees

• Includes Many Commercial/Culinary Fruits

• Alternate & Simple or Compound Leaves

• Four Basic Groups based on Gynoecium & Fruit Type

  • Spirea, Rose, Cherry, and Apple

• Family in Order Rosales

Flowers of Rosaceae

• 5-Merous Flowers

• Non-Fused Petals of Staminal Origin

• Many Stamens

• Variable Gynoecium used to Define Groups

• Hypanthium Present in All Species

  • Forms Rose Hip

Floral Formula of Rosaceae

CA5 CO5 A♾ G[Variable]

Spiraea Group

• Group in Family Rosaceae

• Condensed & Congested Inflorescences

• Follicle Fruits

Flowers of the Spiraea Group

• Perigynous & 5-Merous Flowers

• Relatively Small & Congested

• Short Hypanthium

• Superior & Apocarpic Pistil with 2 to 8 Carpels

Floral Formula of the Spiraea Group

CA5 CO5 A♾ G2-8

Examples of the Spiraea Group

• Meadow-Sweet

• Hardhack

• Ninebark (Physocarpus)

Rose Group

• Group in Family Rosaceae

• Herbs & Some Shrubs

• Compound Leaves

• Produce Stolons or Rhizomes

• One-Seeded Achenes Common

  • Often Modified into Aggregate of Achenes (Strawberry)

  • Modified into Aggregate of Drupelets in Genus Rubus

Flowers of the Rose Group

• Perigynous & 5-Merous Flowers

• Usually Showy

• Hypanthium Well-Developed or Receptacle Elongated

• Superior & Apocarpic Pistils with Many Carpels

Floral Formula of the Rose Group

CA5 CO5 A♾ G♾

Examples of the Rose Group

• Strawberries (Fragaria)

• Raspberries & Relatives (Rubus)

• Prairie Smoke (Geum)

• Agrimonia & Potentilla

• Wild Roses (Rosa)