9309

• UCREFRP Catalog Number: 9309
• Author: Dangaea Times
• Title: Charophycean Algae Invade Land--Phototrophic Conquest of Pangaea Seems Certain
• USFW Year: 1996
• USFW - Doc Type: The Dangaea Times
• Copyright Material: YES

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Early Silurian morning edition

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Charophycean Algae Invade Land--Phototrophic
Conquest of Pangaea Seems Certain

Embryophytes likely to dominate--
Chlorophycean algae stunned

AP-Sometime between mid Ordovician and early
Silurian times, members of the charophycean clade
invaded land. Early reports indicate that these algae
maintained a haplobiontic life cycle, were monoplastidic
and displayed phragmoplast-based cytokinesis. While
representatives of metazoan clades could not be reached
for comment, it is assumed that plant terrestrialization
will have profound effects on the future evolution of
heterotrophic multicellular organisms, which have long
been dependent upon innovation among carbon-fixing
organisms. Indeed, several morphologically complex
members of the red and brown algal clades were willing
to speculate (without attribution) that the colonization
of land by plants may mark the starting point for a
radiation of photosynthetic and nonphotosynthetic
organisms of heretofore unseen proportions.

Although initial speculation centered on whether
members of this land based matrotorphic clade would be
able to withstand the significantly higher levels of UV
radiation on land, preliminary analyses of biochemical
pathways indicate that flavonoids with SPF values of
over 30 have been found among the invading
phototrophs. On an unrelated front, unconfirmed
reports suggest there may have already been trends
towards developmental delay of zygotic meiosis with
the effect that some members of this land plant clade
may now be displaying a distinct alternation of
generations and a significant increase in the number of
spores produced per successful fertilization event.

*********** N otice***********

All graduate students interested in participating
in EPOB 6110, "The Origin and Early
Evolution of Land Plants" (instructor:
Ned Friedman) must register for this course.
Time and place of organizational meeting will
be announced prior to Fall semester.

SEM view of invading Coleochaete, a member of the
outgroup of embryophytes.

Graduate Seminar, Fall Semester
1996--Proposed Topics Include:

* phylogeny of green algae with focus on land plant
outgroups (morphological and molecular cladistic
analyses)
* cell developmental properties and ultrastructure of
charophycean algae and early land plants (evolution
of mitosis, cytokinesis, phragmoplasts,
preprophase bands, plasmodesmata)
* biochemical key innovations/exaptations associated
with origin of land plants
* environmental conditions during the Ordovician and
Silurian
* origin and evolution of alternation of generations
* evolution of the matrotrophic embryo
* synapomorphies of embryophytes (land plants)
* paleobotanical perspective on early dispersed spore
and cuticle fossil record
* evolutionary innovations and trends in the
gametophytes and sporophytes of early land plants
* physiological ecology of early land plants (gas
exchange, water relations, "mycorrhizal" relations)