More questions:

•What are the closest relatives of the Trentepohliales?

•Is the order Trentepohliales a monophyletic group?

•What evolutionary processes have occurred within the Trentepohliales?

• Two lineages in Viridiplantae

•Trentepohlialean taxa are unequivocally within the chlorophycean lineage

• The order Trentepohliales is included within the ulvophycean taxa

• The order Trentepohliales is a monophyletic group

• Phragmoplast?

Relationships within the Ulvophyceae• The marine orders are the most closely related to the Trentepohliales

In all phylogenetic analyses the Trentepohliales emerged as a sister group to the clade containing the Siphonocladales/Cladophorales complex and Dasycladales, both containing representatives mainly from the marine environment!

Relationships within the Trentepohliaceae

•What about the relationships inside of the family?

•Are the genera monophyletic?

•Is the species Cephaleuros virescens, with a world-wide distribution, a monophyletic taxon?

•What is the validity of several morphological characters used for separation at species and genus level?

Four main lineages in 18S rDNA:

Cephaleuros clade

Printzina lagenifera clade

Trentepohlia aurea clade (the generitype)

Trentepohlia iolithus clade

Molecular data challenge traditional classification schemes

Relationships within the Trentepohliaceae

On the basis of our results, Cephaleuros forms a well-defined monophyletic group, representing a more advanced clade

Conversely, Trentepohlia is non monophyletic and the other genera included in the analyses do not represent separate lineages, suggesting the possibility that a major rearrangement at the genus level may be necessary in the future

Relationships among Trentepohlialean genera

Printzina was proposed as a new genus for nine species previously belonging to Trentepohlia

The shape of the sporangia, the arrangement of the sporangiate-laterals, the extensive development of the prostrate parts of the thallus and the occurrence in shaded habitats were considered the key characters separating Printzina from Trentepohlia

The only feature that separates conclusively the two genera is the shape of the sporangia

•globular to reniform in Printzina

•ovoid in Trentepohlia)

The position of Phycopeltis is surprising

Importance of the position of the ostiole in the zoosporangium as key character

T. umbrina (as P. umbrina) with an ostiole opposite to the end of attachment too

T. abietina from Hawaii shows the ostiole clearly opposite to the end of attachment

Our results provide therefore some evidence that the position of the ostiole may be a good phylogenetic marker

•Cephaleuros virescens Kunze, the generitype of Cephaleuros, is generally considered to have a worldwide distribution in tropical and subtropical regions

•Strains of C. virescens do not form a monophyletic group; South Africa and Taiwan are more closely related to C. parasiticus than to other C. virescens

Relationships within a species: Cephaleuros virescens

•These data suggest that the circumscription of C. virescens should be reconsidered

•Morphological characters used to separate this species form similar taxa should be reassessed

•As currently circumscribed, C. virescens represents a complex of morphologically similar entities

•Suriname is the type locality of C. virescens, the actual distribution of this species might be restricted to tropical South and Central America

Current analyses using the chloroplast-encoded rbcL marker confirm 18SSU results

*

Lessons learned

A subaerial habit has developed within the class Ulvophyceae

Morphological criteria traditionally used for the circumscription of genera and species of Trentepohliales are not correlated with evolutionary patterns

Common and world-wide distributed species may represent a species complex of morphologically similar entities (cryptic species)

Many morphological characters used in taxonomy are not phylogenetically relevant

Another subaerial lineage has been found from a group containing representatives mainly from the marine environment

Evolution of the subaerial flora

From textbooks to popular articles there is an appreciation that terrestrial life emerged from the seas. And there is generally no explanation that by “seas” is meant from oceans and lakes – that is, from both marine and freshwater sources

Several representatives of the marine green algal class Ulvophyceae have been found to be members of the terrestrial algal flora

The order Trentepohliales and our newly described taxa are examples of a direct marine invasion of terrestrial environments!

This is in contrast with the general idea that terrestrial floras are descendents of freshwater ancestors and not directly from marine ancestors

A direct marine invasion?

One intriguing, even puzzling, question is:

How marine algae, from ulvophycean ancestors, “jump” into terrestrial habitats and became permanent representatives of the land flora?

A probable answer may came from independent bits of information:

• Fossils

• Ancient changes of sea level

• Pre-adaptive phenotypic plasticity

Records of fossils belonging to terrestrial microchlorophytes have been found as early as the late Eocene (ca. 50 mya)

Dilcher 1965

As Pelicothallus villosus

Described as a fungus

Dilcher 1965

As Pelicothallus villosus

Described as a fungus

Reynolds and Dilcher 1984

As Cephaleuros parasiticus

Re-described as an alga

Later transfer to C. villosus

By Thompson & Wujek 1997

Reynolds and Dilcher 1984

As Cephaleuros parasiticus

Re-described as an alga

Later transfer to C. villosus

By Thompson & Wujek 1997

Fossil subaerial microchlorophytes

Koeck 1939: Fossilie Kryptogamen aus der eocanean Barunkohle des Geiseltales. Nova Acta Leopoldina 6:333-351

Trentepohlia diffusaTrentepohlia diffusa

Trentepohlia aureaTrentepohlia aurea

Fossil trentepohlialean taxa have been reported from the German Eocene

Printz 1939: Vorarbeiten zu einer Monographie der Trentepohliaceen.S. Nytt Mag. Aturvidenskapene B. 80:137-210, Taf.I-XXXII

Koeck 1939: Fossilie Kryptogamen aus der eocanean Barunkohle des Geiseltales. Nova Acta Leopoldina 6:333-351

Trentepohlia rigidulaTrentepohlia rigidula

Trentepohlia aurea var. acutataTrentepohlia aurea var. acutata

Printz 1939: Vorarbeiten zu einer Monographie der Trentepohliaceen.S. Nytt Mag. Aturvidenskapene B. 80:137-210, Taf.I-XXXII

Reliable fossil records established trentepohlialean floras as far as the Eocene 50 mya

By the end of this epoch:

Continents moved closer to their present position

Tropical areas shrinking

A drying period commences

In subtropical latitudes, open woodlands with ferns and shrubby plants replaced forests

Whale ancestors left the land

Trentepohlialean taxa appeared on land over 400 my after the initial colonization of land plants in the Paleozoic (480 mya)

http://3dparks.wr.usgs.gov/

Falkowsky et al. 2004; sea level change

Ancient sea level changes

•Just before Eocene (50 mya) the sea level was at the highest and since then it has been receding

•Much of continental North America, Africa and Australia were exposed

Falkowsky et al. 2004; sea level change

Evolution of floras such as

• Diatoms• Grasses

• Intertidal marine algae live in a variable environment under great physical stress

• This may lead to a selection for a “plastic morphology” were the same genotype is expressing several morphologies under different ecological conditions

• Extant ulvophyceans are examples of this adaptive phenotypic plasticity:

Pre-adaptive phenotypic plasticity

Terrestrial ulvophytes express this adaptive phenotypic plasticity by their ecological ubiquity, ability to grow in several media, and their astonishing capacity to undergo morphological modifications:

Printzina

Trentepohlia

Phycopeltis

Cephaleuros

Information from fossils, ancient sea level changes, phenotypic plasticity and molecular data seem to indicate that:

• Terrestrial ulvophytes did not “jump” from marine to terrestrial habitats: they were “left behind” after sea levels receded during the Eocene

• Ancestors of terrestrial ulvophytes may had the pre-adaptive capabilities to exploit and diversify in the new habitat and become permanent members of the subaerial flora

Many questions still remain to be answered, for example: •Exclusively subaerial algae have a long evolutionary history compared to other green algal orders; however, their fossil evidence is relatively more recent; what is the evolutionary history of this lineage between their ancestral marine origin and their transition to land?

Cladophora-likePrecambrian 700-800 mya

Yakutina and DasycladsCambrian600 mya

TrentepohlialesEocene50 mya

Many questions still remain to be answered, for example:

•Exclusively subaerial algae have a long evolutionary history compared to other green algal orders; however, their fossil evidence is relatively more recent; what is the evolutionary history of this lineage between their ancestral marine origin and their transition to land?

•Another intriguing question is about evolutionary reversals: are there any examples of algae that originated in the continental environment and made a transition back to the sea?

Trebouxiophyceae: Stichococcus marinus?Chlorophyceae: Dunaliella spp. ?Trebouxiophyceae: marine Prasiolales (Prasiola and Rosenvingiella)

Some conclusions

The terrestrial habitat has been colonized by several lineages and more than one green algal group

The Charophycean, Trebouxiophycean and Chlorophycean algae made attempts to colonize the Land via freshwater habitats

The marine Ulvophycean taxa also made this conquest (at least twice)

Subaerial ulvophytes conquered the land using a direct strategy

The history of the conquest of terrestrial habitats by algae is more complex than previously recognized

New molecular techniques (environmental cloning and phylogenomics) may unravel more unknown lineages and unexpected discoveries!

Acknowledgments

Russell L. Chapman, Scripps Institution of OceanographyMike Guiry, National University of Ireland

Paul Broady, University of Canterbury, New ZealandThomas Friedl, University of Goettingen

Fred Brooks, American Samoa Community CollegeAlison Sherwood, University of Hawai’i at Mãnoa

Joe Zuccarello, Victoria University of Wellington, NZBruno De Reviers, Paris HerbariumRicardo Tsukamoto, Sao Paulo, BZ

Jirí Neustupa, Charles University of Prague, Czech Republic

Research at the Phycolab is funded by grants from NSF Systematics-DEB, NEP, MASGC, CA&S/UA and from a RAC/UA to JLB

Fieldwork funds to French Guiana, South Africa, Gabon, Panama, Suriname, Europe, and Southern Mexico partially provided by the Graduate School and the Department of

Biological Sciences at UA

Drs. Fabio Rindi and Sarah M. Noble, graduate students Daryl W. Lam and Haj A. Allali, several undergrads

The PhycoLab in the Web

http://bama.ua.edu/~jlopez

Ongoing Research at the PhycoLab

Subaerial microchlorophytes

South Africa

Morocco

Gabon

Southeastern USA

Panama

French Guiana

Suriname

Europe

and Australia

Assembling the Tree of Life Program:

M. Sc. Ruben Cabrera Marine Archeology

Dr. Ana Maria Suarez Inst. Marine Sciences

University of La Havana

Dr. Beatriz Martinez Oceanology Institute, CITMA

Antonio Vega, Holguin

Ivan Martin, Villaclara

Sandra Siret, Matanzas

Lidice Clero, CIM

Angel Moreira, Cienfuegos

Yusimi Alfonso, Acuario Nacional

Abdiel Jover, Santiago

Juan J. Lake, Camaguey

Mayrene Guimaraes, Cayo Coco

UA – CUBA Seaweed research collaboration