Morphometry of peridinioid dinoflagellates

24 July, 2009

In peridinioid dinoflagellates of the Maastrichtian (Upper Cretaceous) of Trelleborg (Scania, southern Sweden) analyses of the length/width ratio of the pericysts and the endocysts of different species also indicate that the variation of the pericysts generally is greater than that of the endocysts. The endocysts display a less elongated shape which is fairly constant within a species. The specific mean values of the length/width ratio of endocysts range between 0.8 and 1.4 with the median value = 1.0, while the specific mean values for the pericysts range from 1.3 to 4.5, with the median value = 2.1

In these peridinioid dinoflagellates the restricted variation in size and shape of the endocysts indicates that the endophragm was developed under strong genetic control inside the motile, vegetative theca. The pericysts, however, display a wide morphologic variation which may be the result of influences by environmentally controlled factors during the development of the periphragm. This development may have taken place also on the outer side of the motile theca, or even after its decay.

Analyses of the Trelleborg material of the length/width ratio of pericysts and endocysts by reduced major axis in scatter diagrams indicate that within a genus the slopes of the regression lines are close to each other within a genus with statistically significant correlation coefficients. Thus the slope of the regression lines may be used for taxonomical purposes.

See also >> Dinoflagellater: mätningar och klassifikation (in Swedish only)


Dinoflagellater: mätningar och klassifikation

24 July, 2009

 

Dinoflagellater är en grupp encelliga, mikroskopiska alger som kan variera kraftigt till utseendet. Dinoflagellaterna är kända från silur men förekommer främst från mellersta mesozoikum. De är i nutiden en viktig del av havens plankton men lever även i sötvatten.Dinoflagellaternas livscykel har två stadier: det vegetativa stadiet med en theca och ett vilstadium med en cysta. I thecastadiet är cellen aktivt rörlig och omges av ett cellulosaskal. I vilstadiet bildar cellen som skydd mot ogynnsamma miljöförhållanden ett hölje innanför thecan och omkring plasman. Cystan är orörlig.
Hos levande dinoflagellater är det främst theca-stadiet som studerats. Inom paleontologin är det vilstadiet som är intressant eftersom endast cystorna bevaras som fossil.
Eftersom cystan bildas innanför thecans vägg och eftersom båda är kontrollerade av samma genotyp är det naturligt att de kan uppvisa betydande likheter så att cystan motsvarar thecans morfologi. Cystornas form kan variera kraftigt. De kan vara sfäriska och släta, men de har ofta olika slags utskott. Flera former är tillplattade. Peridinioida dinoflagellater är tillplattade och försedda med horn (figur 1). Cystans vägg kan ha varierande uppbyggnad och bestå av ett eller två (eventuellt tre) lager. Den yttre väggen benämns pericyst och den inre väggen endocyst.
  figur 1

 

 

 

 

 

Figure 1. Peridinioid dinoflagellate with pericyst and endocyst.

Analyser av längden och längd/bredd-kvoten hos pericysten och endocysten av olika arter visar att pericystens variation i allmänhet är större än endocystens. Endocysten har en mindre långsträckt form som är tämligen konstant inom en art (figur 2). Medelvärdet för längd/bredd-kvoten för endocysten varierar för de arter jag undersökt mellan 0.8 och 1.4 med medianvärdet = 1.0, medan medelvärdet för längd/bredd-kvoten för pericysten varierar mellan 1.3 och 4.5, med medianvärdet = 2.1

figur 2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 2. Peridinioid dinoflagellate Deflandrea diebeli. Distribution of length (L) and length/width ratio (L/W) of endocyst (E) and pericycst (P). n = number of specimens.

 

En ändring av cystans form mellan olika stratigrafiska nivåer kan visa på ett utvecklingsförlopp som orsakar en morfologisk förändring av fenotypen (figur 3).

 figur 3

 

 

 

 

 

 

 

 

 

 

 

Figure 3. Peridinioid dinoflagellate Paleoperidinium pyrophorum. Scatter diagrams with regression line showing cyst length (L) to cyst width (W) in two different samples. The slope (m), correlation coefficient (r), and number of specimens (n) are recorded on the figure. The correlation betweenL and W is statistically significant on the 0.1% level

 

Förhållandet mellan formen hos pericysten och endocysten är relativt konstant inom ett släkte men varierar mellan olika släkten (figur 4 och figur 5).

 figur 4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 4. Peridinioid dinoflagellates Deflandrea diebeli and Isabelidinium cooksoniae. Scatter diagrams with regression line showing length/width ratio of pericysts (L/W P) to length/width ratio of endocysts /L/W E). The slope (m), correlation coefficient (r), and number of specimens (n) are recorded on the figure. The correlation between L/W P and L/W E is statistically significant on the 0.1 % level.

 figur 5_750

Figure 5. Regression lines based on reduced majoraxis in scatter diagrams showing length/width ratio of pericysts (P) to length/width ratio of endocysts (E) for species of peridinioid dinoflagellates of genera Deflandrea, Isabelidinium, Subtilisphaera, and Trithyrodinium from the Trelleborg boring core T-1 (southern Sweden). The slope (m), correlation coefficient (r) and its significance level (* = 5 %, ** = 1 %, *** = 0.1 %), and number of specimens (n) are recorded on the figure.

 

Den begränsade variationen av storleken och formen hos endocysten av de studerade dinoflagellaterna visar att den inre väggen utvecklades under genetisk kontroll inuti en theca. Pericysten visar en vid morfologisk variation som kan vara resultat av påverkan av miljöfaktorer under den yttre väggens utveckling.

De båda släktena Isabelidinium och Eurydinium skiljs genom formen hos endocysten. I Isabelidinium skall längden av endocysten vara lika stor som eller mindre än bredden (L/W<1.0) medan i Eurydinium skall längden av endocysten vara större än bredden (L/W>1.0).

 figur 6

 

 

 

 

 

 

 

 

Figure 6. Peridinioid dinoflagellate Isabelidinium cooksoniae. Distribution of length (L) and length/width ratio (L/W) of endocyst (blank) and pericycst (dotted). n = number of specimens.

 

I det material jag studerat varierar längd/bredd-kvoten hos en art mellan 0.6 och 1.2. Kvoten är normalfördelad och har medelvärdet = 0.9 (figur 6). Detta visar att det inte finns någon anledning att särskilja dessa två släkten med endocystens form som kriterium.

 

Referens

Lindgren, S., 1984.
Acid resistant peridinioid dinoflagellates from the Maastrichtian of Trelleborg, southern Sweden. (Summary in Russian.) Stockholm Contrib. Geol., 39(6): 145—201. Stockholm. ISSN 0585-3532. ISBN 91-22-00519-6. — Buy at the lowest prices among books in Sweden.

Morphometry of modern Chlorococcales and fossil Leiosphaeridia (algae)

24 July, 2009

 

The size is not a sole diagnostic character. Anyhow related modern taxa of the rank of genus as well as species seem to have a limited size range and measurements may be important features for determination of modern algae.

The size distribution in Leiosphaeridia may be compared to vegetative stages of modern unicellular Chlorococcales. The knowledge of size relations between vegetative cells and resting cysts is too fragmentary for comparisons.

For comparisons of dimensions among taxa a “size difference” value (SD) may be calculated as the size range value in per cent of the minimum size value (Lindgren 1981).

size


Figure 1
A. Cumulative diagram showing size differences in 49 genera of the Chlorococcales. Size difference of Leiosphaeridia is indicated by an L.
B. Cumulative diagram showing size differences in 257 species of the Chlorococcales (curve C), and in 55 species of Leiosphaeridia (curve L).
The size difference is calculated as the size range value in per cent of the minimum value. (From Stockholm Contrib. Geol., 38(1): 8, figure 1)


In 49 genera of the Chlorococcales tabulated from Philipose (1967) the size difference varies between SD = 4 and SD = 5400, with a median value of SD = 250 (fig. 1A). Only in six genera the size difference exceeds SD = 1000, and only in two it exceeds SD = 4000. Specimens of Ankistrodesmus Corda 1838 emend. Ralfs 1848 (seven species) range from 3 µm to 165 µm (SD = 5400), and specimens of Chlorococcum Fries 1820 (three species) range from 2 µm to 109 µm (SD = 5350).

In Leiosphaeridia the size range is recorded as 8—440 µm. The size difference is SD = 5400.

Thus the size difference for genus Leiosphaeridia is extremely high, but not quite impossible for a natural taxon. In described species of Leiosphaeridia, however, the size range is far more restricted than in modern Chlorococcales (fig 1B).

In 257 species of the Chlorococcales, also tabulated from Philipose (1967), the size difference in vegetative cells ranges between SD = 4 and SD = 1163, with a median value of SD = 100. 13.6 % of the difference values exceed SD = 200 and 4.7 exceed SD = 350.

In 55 species of Leiosphaeridia (including Protoleiosphaeridium) the size difference ranges from SD = 3 to SD = 203, with a median value of SD = 58.

The values of the size differences are summarized in table I

 


Table I
Size differences in modern Chlorococcales and fossil Leiosphaeridia

 

Number 

 

 

 

 

Size difference 

 

 

 

 

of taxa 

 

 

 

 

Minimum 

 

 

 

Maximum 

 

 

 

Median 

 

 

 

Mean 

 

 

 

Genera             
Chlorococcales

49

 

 

 

 

4

 

 

 

5400

 

 

 

250

 

 

 

557

 

 

 

Leiosphaeridia 

1

 

 

 

   

5400

 

 

 

   
             
Species             
Chlorococcales

257

 

 

 

 

4

 

 

 

1163

 

 

 

100

 

 

 

128

 

 

 

Leiosphaeridia 

55

 

 

 

 

3

 

 

 

203

 

 

 

58

 

 

 

62

 

 

 

 The size difference is calculated as the size range value in per cent of the minimum value.

 

 

 

 

  

 

 

 

 

  

BACK TO


Morphology and taxonomy
Botanical affinities
Diagnostic features in modern algae
  FORWARD TO


Genus Leiosphaeridia
Distribution of Leiosphaeridia

References

Lindgren, S., 1981.
Remarks on the taxonomy, botanical affinities, and distribution of leiospheres. (Summary in Russian) Stockholm Contrib. Geol., 38(1): 1—20. Stockholm. ISBN 91-22-00500-5. ISSN 0585-3532. — Buy at the lowest prices among books in Sweden.
Philipose, M.T., 1967.
Chlorococcales. Indian Counc. Agric. Res., New Delhi. 365 p.

 

 

Web Link

Steiner, M., 1997. Chuaria circularis Walcott 1899 — “megasphaeromorph acritarch” or prokaryotic colony? Acta Universitatis Carolinae, Geologica, 40: 645—665. Prague.



Morphometry of fossil algae

24 July, 2009

 

Morphometry is the study of form, shape, and size in organisms.

Biometry is the science and technology of measuring and statistically analyzing biological data. Biometry originates from statistical applications for agriculture, but its scope now includes diverse areas of the life sciences by the application of statistics, probability, mathematics, system analysis, and computer science.
In information technology, biometry usually refers to technologies for measuring and analyzing human body characteristics such as fingerprints, eye retinas, and voice patterns, especially for authentication someone.

Biostatistics usually refers to the application of statistics to the biological sciences. Statistics is a set of tools for collecting and summarizing data, and for using the data to draw inference from the population which it is supposed to represent. The statistical methods used in biostatistics do not differ substantially from those used in statistics.

 

Morphometry of modern Chlorococcales and fossil Leiosphaeridia (algae)

Dinoflagellater: mätningar och klassifikation  In Swedish

Web Links

 

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