Algae World: Sellaphora

Why choose Sellaphora?

Sellaphora is an attractive choice for observational and experimental studies of many kinds, but particularly for research into diatom speciation and biogeography, because: 

1. Sellaphora species are common in the epipelon (motile sediment-dwelling communities) in many different kinds of lakes and rivers (spanning a wide range of pH, for example) throughout temperate and tropical latitudes.
2. The cells are large enough (usually between 15 and 80 µm long) to allow many features of the cell and cell wall to be seen relatively easily with the light microscope.
3. Cells are motile and generally solitary, which makes it easier to homogenize cultures and natural populations for experiments.
4. Many species can be grown without difficulty in the laboratory and often achieve division rates of 1 per day.
5. Pairing of sexualized cells is active, providing early warning that meiosis and sexual reproduction are imminent.
   
6. Only one gamete is produced per gametangium and these are differentiated into male and female, providing useful markers during sexual reproduction.
7. DNA extraction is straightforward (in contrast to some other diatoms, such as Mastogloia)
8. The cell is topographically simple (basically an elongate box with flat top and bottom, like a date box), making photography  and observations of cell structure easy.
9. Cell shape and pattern provide enough characters for it to be possible to make preliminary classifications and identifications of species using the light microscope.
10. The taxonomy and nomenclature of the genus are fairly straightforward (compared to genera such as Navicula, Nitzschia and Pinnularia), although the position is deteriorating rapidly.
11. There is a fossil record.

As a result of the features listed above, other advantages have come about:

1. The fundamentals of cell and cell-wall structure, cytological changes during the cell-cycle, the life-history, sexual reproduction, mating systems and auxospore development are well-documented in easily accessible literature.
2. Molecular genetic studies have established a skeleton phylogeny for the genus within which more detailed studies can be planned.
3. DNA bar-codes have been developed for easy and ± certain identification of species.
4. Microsatellite markers are being developed to investigate genetic structure and gene flow within and between populations.
5. We have decided to make this website!