Morphometric variation of Nitzschia frustulum var. symbiotica the most common endosymbiotic diatom in larger foraminifera
Lee, J.J.1,2 and Correia, M.1
1Department of Biology, City College of CUNY, Convent Avenue and 138th St.,
New York, NY 10031, USA
2 Department of Invertebrates, The American Museum of Natural History,
Central Park West at 79th St., New York, NY 10024, USA
Endosymbiotic diatoms of larger foraminifera are frustuleless in their hosts and they reproduce in that state for many generations. Asexual reproduction of hosts leads to serial passage of the diatoms, and their reproduction keeps pace as the juvenile hosts grow to maturity. Frustule characteristics would seem to have no adaptive value for the endosymbiotic diatoms within their
hosts, but they form frustules when they are released into culture media. Populations of Nitzschia frustulum var. symbiotica from two Caribbean hosts were quite different from those isolated earlier from Indo-Pacific hosts. The characters of each clone were stable. Nine populations, covering the extremes of character ranges, were measured and described. Principle component analysis showed variance among strains was significant. Greatest variance was found in keel puncta and striae, suggesting very little likelihood that the strains were identical in these characteristics.
The variation in the populations of Nitzschia frustulum var. symbiotica from Caribbean larger foraminiferan hosts piques curiosity about the genetic mechanisms by which this diversity was reached. What kinds of evolutionary drift should we expect to see in characters (frustule) which have no selection or survival value in these organisms, because they are not even formed while they are in their hosts? If this endosymbiont species complex is rare in nature, but common in particular hosts, could we use the observations on endosymbiont population diversity to explore questions of host/symbiont coevolution? This last question is quite complex because neither the hosts, nor the symbionts, have finical relationships with each other.
| LOCATION |
DATE |
TIME |
| Lecture Hall I |
Tuesday, April 7 |
02:20 pm |