Transcript 01 Introduction

Plants – Targeted Review
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2
Order
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Part 1
http://www.youtube.com/
watch?v=ahXIMUkSXX0
Part 2
http://www.youtube.com/
watch?v=lOIP_Z_-0Hs
Part 3
http://www.youtube.com/
watch?v=14-NdQwKz9w
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Inner Life of The Cell
http://multimedia.mcb.harvard.edu/innerlifeseries
.html
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Largely beyond the scope of this class
Big Picture Stuff – not details!
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What is a Plant?
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2 kingdoms ….. Plant
& Animal
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Animals moved about;
Plants didn’t and were
photosynthetic
Fungi
Photosynthetic protists
(aka “algae”)
Land Plants
Elysia chlorotica :: solar-powered sea slug
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Division Phase of the Cell Cycle
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Division of the nucleus is karyokinesis
There are two types:
Mitosis - Duplication division
 Meiosis - Reduction division
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Division of the cytoplasm is cytokinesis
Centrioles/Centrosome
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Absent
Pinophyta
 Angiosperms
 Some fungi
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Present
Some fungi
 Male gametes of

o
o
o
o
o
Charophytes
Bryophytes
Ferns and fern allies
Cycads
Gingko
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Mitosis
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Four phases:
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Prophase
Metaphase
Anaphase
Telophase

I Proposed Marriage to Anna by Telephone,
Carefully

In or near meristem cells
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Less Common Types of Division
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Karyokinesis without
cytokinesis
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Multinucleate cells -coenocytes
Cytokinesis without
karyokinesis

Most common in algae,
fungi, and the nutritive
tissues of seeds
Unusual Mitosis
may represent
evolutionarily
older lines
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Cell Division: Prokaryotes

Division by binary fission
Circular DNA replicates
attached to the cell
membrane
 Replicates separated by
membrane growth
 Cytokinesis occurs by a
process of infurrowing
 The plasma membrane pulls
inward and pinches in two

Division: Chloroplasts and
Mitochondria
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DNA is replicated as in
prokaryotes
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Division occurs either by in
furrowing or by being pulled in
two
Replication -- not coordinated
with the cell cycle
Appears continuous
throughout interphase.
Gamete Types
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Gametes

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Process? It depends!
Meiosis …..
Animals
 Some protists
 Some Algae
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Mitosis
Plants
 Some Algae
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A brief note on ploidy …..
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Fertilization and meiosis alternate
in sexual life cycles

Life cycle -- generation-to-generation sequence of
stages in the reproductive history of an organism
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Sexual Reproduction -- Alternation of meiosis and
fertilization
Life cycles -- timing of meiosis and fertilization
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Gametic
Meiosis
Key
Haploid gametes (n = 23)
Haploid (n)
Ovum (n)
Diploid (2n)
Sperm
cell (n)

In animals, meiosis
produces gametes


The only haploid
cells in animals
Gametes fuse to
form a diploid
zygote
MEIOSIS
Ovary
FERTILIZATION
Testis
Diploid
zygote
(2n = 46)
Mitosis and
development
Multicellular diploid
adults (2n = 46)
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Gametic
meiosis
Animals, some
protists, some
algae
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Zygotic Meiosis
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In most fungi and some protists
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only diploid stage is the single-celled zygote
Zygote -- haploid cells by meiosis
Haploid cell grows by mitosis into a haploid
multicellular organism
The haploid adult produces gametes by mitosis
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Zygotic meiosis
Fungi, some algae
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Alternation of Generations
Sporic Meiosis
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Plants and some algae
Two multicellular “generations” -- one diploid and
one haploid
Sporophyte (diploid) -- makes haploid spores by
meiosis
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
Spore germinates -- haploid organism called a
gametophyte
Gametophyte (haploid) -- haploid gametes by
mitosis
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Sporic
meiosis
Plants, some
algae
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Taxonomy

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Naming and classifying
species
Early goals:
Develop natural
system of
classification –
grouping closely related
organisms
 Assigning plant names
based on phylogenetic
relationships

Concepts

Modern Goals
understanding evolutionary lines
 system of nomenclature reflecting phylogeny
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Taxonomy – study of how things are classified
Phylogenetics -- Reconstructing evolutionary
history

Phylogeny is reality; classification systems are
hypotheses.
Figure 1: Five recently published representative topologies among eudicots (Eud),
monocots (Mon), magnoliids (Mag), Ceratophyllaceae (Cer) and Chloranthaceae (Chl).
From: Zeng, L., Q. Zhang, R. Sun, H. Kong, N. Zhang and H. Ma. 2014. Resolution of deep angiosperm phylogeny using conserved
nuclear genes and estimates of early divergence times. Nature Communications 5, Article number: 4956 doi:10.1038/ncomms5956
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Concepts
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Phylogenetics -- Reconstructing hypothetical
evolutionary history
Knowledge incomplete and imperfect
classification systems are only approximations
 Phylogenies are only hypotheses
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A phylogeny is only as robust as the data!
Species
Panthera
Mephitis
Lutra lutra
Canis
Canis
pardus
mephitis
(European
familiaris
lupus
(leopard) (striped skunk)
otter)
(domestic dog) (wolf)
Genus
Systematists depict
evolutionary
relationships in
branching
phylogenetic trees
Panthera
Felidae
Order
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Family
Systematics:
Links Taxonomy and Phylogeny
Mephitis
Lutra
Mustelidae
Canis
Canidae
Carnivora
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Reading Trees
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Unrooted Trees
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Often drawn as network
No outgroup
Topology
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Equivalent
Direction of time
different
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Topology
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Order of terminal nodes
is irrelevant – only
branching order
important.
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Topology
B
D
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Topology
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A – cladogram: information
contained in branching order
B – phylogram: branch
lengths proportional to
measure of divergence
C – phylogram: branch
lengths scaled to time
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Species
Panthera
Mephitis
Lutra lutra
Canis
Canis
pardus
mephitis
(European
familiaris
lupus
(leopard) (striped skunk)
otter)
(domestic dog) (wolf)
Genus
Clades can be
nested in larger
clades, but not all
groupings or
organisms qualify
as clades
Panthera
Felidae
Order

Family
Cladistics / Phylogenetics
Mephitis
Lutra
Mustelidae
Canis
Canidae
Carnivora
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Phylogenetic Groupings
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Phylogenetic Groupings
What’s a
monophyletic
group?
How many
monophyletic
groups?
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Phylogenetic Terminology
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Apomorphy – derived
character
Plesiomorphy –
Ancestral character
Autapomorphy –unique
& characteristic to
monophyletic group
Synapomorphy – shared
derived characters
Homoplasy – similarity
not due to common
ancestry
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Grouping Species: The Basic
Idea

Kingdoms and domains -- broadest units of
classification

King Philip Cleverly Ordered Fried Green squid
…
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Species Genus Family
Order
Class Phylum Kingdom Domain
Ursus
americanus
(American
black bear)
Ursus
Ursidae
Carnivora
Mammalia
Chordata
Animalia
Eukarya
Levels of Taxonomic Hierarchy
Seven primary levels
(8 counting Domain!)
© 2009 W.W. Norton &
Company, Inc. DISCOVER
BIOLOGY 4/e
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Nomenclature
Taxonomic rank
Fungi
Algae
Plants
Phylum
-mycota
-phyta
-phyta
Subphylum
-mycotina
-phytine
-phytina
Class
-mycetes
-phyceae
-opsida
Subclass
-mycetidae
-phycidae
-idae
Order
-ales
-ales
-ales
Suborder
-ineae
-ineae
-ineae
Family
-aceae
-aceae
-aceae
Subfamily
-oideae
-oideae
-oideae
International Code of Botanical Nomenclature –
http://ibot.sav.sk/icbn/main.htm
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Families, Genera & Species
Family – Rosaceae (ca. 100 genera worldwide)
 Genera
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 Amelanchier
 Malus
 Prunus
 Pyrus
 Rosa
 Rubus
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Families, Genera & Species
Family Rosaceae – species Rosa multiflora
 Species in different genera

 Amelanchier
arborea -- serviceberry
 Malus pumila – common apple
 Prunus americana – American plum
 Pyrus communis – pear
 Rubus odoratus – wild blackberry

Species in the same genus
 Rosa
canina – Dog rose
 Rosa setigera – Prairie rose
 Rosa carolina – Carolina rose
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Binomial Scientific Names
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The scientific name -- genus name and specific epithet
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Names are treated as Latin and always underlined or
italicized
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The first letter of the genus name is always capitalized
The first letter of the species name is always lower case
Authorities, “variety,” etc. unitalicized.
Species name is always paired with its genus name

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Unique
Properly includes authority
Homo sapiens
Specie == Money
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Biological Diversity
Biologists have named about 2 million species
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Biological Diversity
Estimates of total species range from 10 million to over 200 million
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Early Biological
Thought

Expressed by ancient Greek
philosophers
Plato (427-347 B.C.)
 Aristotle (384-322 B.C.)
arranged all organisms on a
linear scale of increasing
complexity (“ladder of Nature”)

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History of Classification Schemes
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Until 1969 – 2 Kingdoms (Plant & Animal)
1969 – Robert Whittaker: 5 Kingdoms
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all bacteria in Kingdom Monera
1990 – Carl Woese: 3 Domains
ARCHAEA
BACTERIA
EUKARYA
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The Three Domains of Life
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At the highest level, life is classified into three
domains:
Bacteria (prokaryotes)
 Archaea (prokaryotes)
 Eukarya (eukaryotes)

o
o
o
o
Kingdom Protista
Kingdom Plantae
Kingdom Fungi
Kingdom Animalia
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The Five Kingdoms of Life
 Prokaryotes
 Archaea
– Domain Archaea
 Bacteria
– Domain Bacteria
 Cyanobacteria – Domain Bacteria
 Animals – Domain Eukarya
 Plants – Domain Eukarya
 Fungi – Domain Eukarya
 Protists – Domain Eukarya
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Taxonomy
A Constant State of Flux

Classifications Change ……
Systematists regularly propose changes in
classification
 Classifications Change When New Information Is
Discovered


A classification is …….
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The Three Domains of Life
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Keeting et al. 2005 Trends in Ecology & Evolution 20(12): 670-676
THE EUKARYOTIC TREE OF LIFE
Fungi
you are here
Slime Molds
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Another Classification Scheme
http://comenius.susqu.edu/biol/202/taxa.htm
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The Three Domains of Life
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Phylogenies of Bacteria, Archaea and eukaryotes
inferred from concatenated rRNA.
Eukarya
Archaea
Notice that
Eukaryotes are
embedded
within Archaea
in 3 of the 4
trees!
Bacteria
Williams T A et al. Proc. R. Soc. B
doi:10.1098/rspb.2012.1795
©2012 by The Royal Society