Download Spores versus seeds, and then fruit

BIOL 1010 Introduction
to Biology: The
Evolution and Diversity
of Life. Spring 2011
Sections A & B
Steve Thompson: [email protected]
http://www.bioinfo4u.net
1
Monday, March 7, 2011
Spores versus seeds,
and then fruit.
Ferns and their allies ruled the plant world for 250
million years. Their deposits created our coal reserves.
But then along came a new evolutionary invention —
the seed, and then, even better, the fruit!
The evolution of the seed marks one of the most
important innovations in the history of land plants,
leading to enhanced survival and dispersal capabilities
and to greater mating control.
2
Monday, March 7, 2011
First came the “naked
seeded” Gymnosperms.
All seeds allow plants to live and reproduce
in drier habitats than the more ‘primitive’
plants can ever achieve. Plus . . .
Pollen grains produce sperm cells – they don’t
need free water for fertilization to occur.
The seed is the young sporophyte packaged
with a food supply in a tough outer coat.
Gymnosperm means naked seed – the seeds
are not enclosed in fruits.
3
Monday, March 7, 2011
Remember how they fit in the ToL.
Club mosses &
ferns & fern-like:
Seedless, vascular
plants
Vasculature
Terrestrial
the Bryophytes
Seeds
http://tolweb.org/Embryophytes/20582
All the Spermatopsida (seed plants) – a true clade –
separate from all the ‘primitive’ plants.
4
Monday, March 7, 2011
And within the
Spermatopsida . . .
Monday, March 7, 2011
Gymnosperms
http://
tolweb.org/
Spermatopsida/
20622
The
Gymnosperms are
a paraphyletic
grouping,
whereas, the . . .
Angiosperms are
a distinct
monophyletic
clade
?
5
However, that
Palmer, Soltis,
and Chase
article makes
Gymnosperms
monophyletic.
http://
www.amjbot.
org/cgi/
content/full/
91/10/1437
Either way,
the
Angiosperms
definitely are
a true clade.
6
Monday, March 7, 2011
And whatever scheme you choose to
use, an ancestor of the Gymnosperms
evolved into the Angiosperms.
7
Monday, March 7, 2011
So, first a little more about Gymnosperms.
There are around 800 – 1100 living species.
They arose in the late Carboniferous and
dominated the earth while the dinosaurs ruled.
They include the tallest tree (Redwood), most
massive tree (Giant Sequoia), and longest living
tree (Bristlecone Pine) on Earth.
They have huge genomes – at least ten times
the size of the human genome!
http://en.wikipedia.org/wiki/Gymnosperm
and . . .
http://www.huh.harvard.edu/research/
mathews-lab/atolHtmlSite/index.html
8
Monday, March 7, 2011
The conifers are the most
‘advanced’ and specious.
There’s about 700 – 800 living species.
They’re quite diverse, being trees or shrubs; with
leaves ranging through all types of needles, and
fronds, to just little reduced scales.
And they include pines, firs, spruces, junipers,
cedars, hemlocks, yews, and cypresses.
They all produce egg cells and pollen in cones.
Commonly known as evergreens because most do
not loose all their leaves at once in the Autumn.
http://en.wikipedia.org/wiki/Pinophyta
9
Monday, March 7, 2011
The conifers are also called the Pinophyta.
Pine, Spruce, Larch,
Douglas-Fir, true Fir,
some Cedars, Hemlock
ancient south
hemisphere trees
Japan’s Umbrella-pine
Cypress, some Cedars,
Juniper, Sequoia,
Redwood
Plum-yew
Yew
10
Monday, March 7, 2011
This is a conifer
from my home
state, Arizona, the
Pinon Pine. Looks
like it’s hanging on
the edge of Oak
Creek Canyon, near
Sedona. Some of
the largest forests
in the world are
coniferous: http://
www.youtube.com
/watch?
v=fnkTwWV1PwU
11
Monday, March 7, 2011
The Cycads are the second group of
Gymnosperms.
They may be a sister group to the conifers, and
are primarily tropical or subtropical. They
have . . .
Palm-like fronds with very large cones.
Many are used as ornamentals, e.g. the ‘Sago
Palm’ planted extensively here in the Deep South.
Many species are near extinction due to slow
growth, low reproductive rates, and habitat loss.
http://en.wikipedia.org/wiki/Cycad
12
Monday, March 7, 2011
Here’s a
picture and
a video . . .
Of cone
development
(time lapse).
http://
www.youtube.com
/watch?
v=Ryk6PEmDzfo
13
Monday, March 7, 2011
The third third group of
Gymnosperms is the Ginkgo.
This is also called the Maidenhair Tree; it is
a ‘living fossil,’ dating back unchanged for
270 million years, and has . . .
Only one living species: Ginkgo biloba.
And it’s extinct in the wild, but is highly
used in horticulture. And is . . .
Used as a traditional herb for memory and
concentration improvement.
http://en.wikipedia.org/wiki/Ginkgo
14
Monday, March 7, 2011
The Ginkgo (not
Gecko), and fossil
evidence from the
Eocene.
15
Monday, March 7, 2011
Finally, the Gnetophytes.
Either a sister group to the Gymnosperms, or
the Angiosperms,
depending on who you talk to!
They are perhaps the most distinctive and
bizarre of the seed plants. And comprise
three genera:
Some Gnetums are trees, but some are vinelike; Welwitschia is another ‘living fossil,’
that is a prostrate shrub in African deserts;
and Ephedra is an arid climate bush, a.k.a.
Mormon-Tea.
http://en.wikipedia.org/wiki/Gnetophyta
16
Monday, March 7, 2011
Ephedra (on right) is
common in the
Southwest USA
deserts.
Welwitschia (below) is
just plain weird.
17
Monday, March 7, 2011
Gymnosperm sex involves . . .
Large female sporophyte cones bear t wo sporangia; these are called ovules.
Each ovule produces four haploid megaspores using meiosis.
One megaspore develops into the female gametophyte.
The female gametophyte slowly produces t wo to six egg cells.
Separately, but simultaneously, small male sporophyte cones bear sporangia
that use meiosis to produce haploid microspores. The . . .
Microspores become pollen grains (immature male gametophytes).
The pollen is usually wind blown, sometimes for great distances.
Then the pollen grain settles bet ween scales of female cones and sticks to
the sticky exude located there. This is “pollination.” Then the . . .
Pollen grain germinates. This leads to the creation of the . . .
Pollen tube, which grows through the ovule toward the egg cell.
Inside the pollen tube a specialized cell divides mitotically to make t wo
haploid sperms (since the pollen are also haploid). One of those . . .
Sperm fertilizes the haploid egg resulting in the diploid zygote (sporophyte
generation). It’s really slow – sometimes 15 months from pollination.
Within the ovule, haploid tissue of the female gametophyte nourishes the
developing embryo (sporophyte generation) and then a tough seed coat is
formed (but no fruit).
18
Monday, March 7, 2011
That’s a
lot, here’s
the text’s
diagram.
19
Monday, March 7, 2011
Still a lot . . . how about a video?
http://www.youtube.com/watch?v=D9byVQxvMXs
20
Monday, March 7, 2011
On to the Angiosperms
These are the flowering plants (95%+ of all
‘advanced’ plants).
Flowers are reproductive structures that
produce pollen and egg cells.
After fertilization flower parts develop into
the fruit, which contains seeds.
Flowers and fruits help disperse pollen and
seeds. Fruits furthermore help protect the
seed(s).
But not all flowers are showy, nor are all
fruits yummy.
21
Monday, March 7, 2011
Remember where they come from.
22
Monday, March 7, 2011
There are several clades within the Angiosperms
(from the Palmer, Soltis and Chase paper).
23
Monday, March 7, 2011
And as seen at ToL:
Where’s there’s a great discussion of their characteristics,
phylogeny, and fossil history, with estimated divergence dates!
http://tolweb.org/Angiosperms/20646
24
Monday, March 7, 2011
And I even found a pretty cool video
about their origin.
http://science.discovery.com/videos/mammals-vsdinos-shorts-first-flowering-plants.html
25
Monday, March 7, 2011
And they’re very diverse.
From left to right: banana palm, red maple,
passion vine flower, and cattail.
26
Monday, March 7, 2011
Within all the Angiosperm clades, we’ll look at the
Monocots and the Eudicots a bit more closely.
The Monocotyledons are one clade.
It means “one cotyledon.” This is the first
leaf structure to appear in the embryo.
There’s about 70,000 species, including
orchids, lilies, grasses (including most grains),
palms (including banana), ginger, and lots
others (usually all with parallel venation in
the leaves).
http://en.wikipedia.org/wiki/
Monocotyledon and . . .
http://tolweb.org/Monocotyledons/20668
both have great articles.
27
Monday, March 7, 2011
And some
really nice
photo’s
http://tolweb.org/
images/
Monocotyledons/
20668,
but not all are so
showy, as most
grass flowers are
quite inconspicuous.
28
Monday, March 7, 2011
Eudicots
Dicotyledons are polyphyletic and have
almost 200 thousand species,
They all have t wo cotyledons. Dicots
include:
Magnolias, water lilies, oaks, tomatoes, on
ad infinitum.
Eudicots are monophyletic within the dicots.
http://en.wikipedia.org/wiki/Dicotyledon
and http://en.wikipedia.org/wiki/Eudicot
And http://tolweb.org/eudicots/20666
29
Monday, March 7, 2011
ToL has a ton
of great
images again.
http://tolweb.org/
images/eudicots/
20666
This is a Saguaro,
the icon of the
desert, but it only
grows in the
Sonoran Desert,
mainly south &
central Arizona!
Monday, March 7, 2011
30
Here’s a decent video on the differences
bet ween monocots and dicots.
http://www.youtube.com/watch?v=4uq5ybc4vts
31
Monday, March 7, 2011
Angiosperm sex is pretty similar to Gymnosperm’s.
The sporophyte is the only conspicuous generation.
Pollen grains (the male gametophyte) produce sperm cells.
But there are some important differences:
Flowers are the reproductive organs (not cones). Many are in a . . .
Tight coevolutionary path with a particular animal pollinator and a
particular angiosperm. But not all, some are wind or rain pollinated.
Angiosperm seeds develop inside the flower’s ovary following
fertilization.
Other floral parts develop into a fruit that houses the seed(s)
(that is the seeds are not “naked”).
A fruit’s main function is seed protection and dispersal by various
means, including by being tasty, being sticky, or being very light.
A double fertilization yields the embryo plus the endosperm.
The endosperm supplies nutrients to the germinating seedling.
32
Monday, March 7, 2011
What about a picture for this?
33
Monday, March 7, 2011
How about another video?
http://www.youtube.com/watch?v=ph7Ex8rQ-IA
34
Monday, March 7, 2011
And, if there’s time, here’s a very
nice overview video of all plants.
But it makes
one big
mistake –
Fungi are
not plants!
http://www.youtube.com/watch?v=i_QEPjNCSK8
35
Monday, March 7, 2011
Next time we move out of the
plant world into the
Unikonts, that clade that
contains the animals.
And look at that group that was
once thought to be related to the
plants, the Fungi. However, now
we know that it is actually a
sister clade to the ‘true animals!’
36
Monday, March 7, 2011