Dwarf males

Rouse GW, Goffredi SK, Vrijenhoek RC (2004) Osedax Bone-Eating Marine Worms with Dwarf Males. Science 305 668... 

Obst, M., Punch, P. (2003). Dwarf male of Symbion pandora (CycUophora). Journal of Morphology 255,261-278. 

The morphological data obtained for P. cygnisetum is based on the examination of herbarium specimens of this species that are preserved in L and hb. Blocher. All specimens examined come from Chile. Selected specimens are Crosby 11682 (L), 12155 (L), Deguchi BSE 994 (L), Neger s.n. (L, c. 1897, Anden von Villarica dwarf males), BlOcher 236 (hb. Blocher dwarf males). 

Morphological Studies within the Ptychomniales, with Emphasis on the Evolution of Dwarf Males... 

The objectives of this chapter are several first, to resolve phylogenetic relationships within the Ptychomniales using DNA sequence data second, to reconstruct ancestral character states within the Ptychomniales and third, to test whether the presence of dwarf males correlates to morphological characters and the epiphytic habitat. 

Tests of correlated evolution of dwarf males with the ranaining morphological features and the epiphytic habitat were conducted using Discrete (Pagel, 1999). This was accomplished by first fitting a model to the data in which the two characters were allowed to evolve independently. The likelihood of this model was then compared to the likelihood of a more complicated model in which the characters evolve in a correlated fashion, and a likelihood ratio was calculated between the dependent and the independent model to test if the more complicated model was a better fit to the data than was the model assuming independent evolntion. 

The evolution of dwarf males was significantly correlated with most of the morphological characters except seta length (Character 11), gemmae (13), endostome cilia (16), exostome development (17), and inner perichaetial leaf plication (18). In addition, there is no statistical support for correlated evolution of dwarf males with the epiphytic habit. The statistics of the correlation tests are presented in Table 18.4. 

Three character states were found to be significantly more likely to evolve in the presence of dwarf males, namely, teeth on dorsal leaf lamina (8), mitrate calyptrae (14), and furrowed capsules (15). With statistical support, the correlation tests suggest that dwarf males are more Ukely to evolve in the presence of rugose leaves (7) and paraphyllia (10). 

As mentioned above. Discrete can analyse only binary characters and any multistate character has to be either excluded from the analyses or transformed into binary ones. For some of the characters used in the present analyses, multistate codings are possible. For instance, the presence of dwarf males (character 1 state 1) can be coded as simple and unbranched, as for Garovaglia, or larger and branched, as for Euptychium, Glyphothecium and Cladomnion. It is therefore possible that the uncertainties in ancestral character state reconstructions might be an artifact of the binary... 

Likelihood Ratio Test Statistics (LRT) and Probabilities (p-Value) of Tests of Correlation of Dwarf Males with Morphological Characters and the Epiphytic Habitat... 

The results of the correlation tests suggest that the presence of teeth on the dorsal leaf lamina, mitrate calyptrae and furrowed capsules, are more likely to evolve when dwarf males are present. It seems reasonable that dorsal teeth, by providing further establishment points and protection for incoming spores, may be beneficial for taxa with dwarf males, but it is difficult to envision the benefits of mitrate calyptrae and furrowed capsules. It is worth mentioning, however, that correlation does not necessarily imply causation. 

Perhaps the most striking inference gained from the current study is that the evolution of dwarf males appears to be significantly correlated with several morphological traits. In addition, dorsal teeth are more likely to evolve when dwarf males are present whereas rugose leaves promote... 

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