Null hypothesis.
- There will be no difference between the parasite and what host it infects, thus no host specificity.
- There will be no difference in the size of the host and the number of parasites that infect it.
- There will be no correlation between host habitat and parasite specificity.
Method.
Take four samples of each of the two specimens L.littorina and L. saxtilis and measure in mm the height of their shells. Gently take one sample at a time and gently tap with a hammer and remove the shell. Cut of the foot and mount the visceral hump on a glass slide. Using another glass slide gently press down on the other slide to spread out the sample. Under the light microscope examine the sample for infection and record the stage at which infection is occurring and the trematode that is infecting the sample. Carry out the procedure for all of the samples.
Results
Fig1 Percentage of infected and uninfected and determination of parasite
host specificity using Yates correction of continuity chi square.
Fig2 Fig3
Discussion.
With regards to Cercaria littorina saxatilis V and Microphallus pygmaeus the null hypothesis was rejected and thus there was a significant difference in host specificity for L. saxitilis. Therefore there may be an underlying factor influencing the reason for this result beyond the boundaries of this observation that is linking these two particular parasites with the above host species. The null hypothesis was accepted with regards to the size of the two specimens used and their parasite number and also their habitat type. Hence there is no specificity by the parasites found in the size and habitat type of their host. It seems likely that they are not infecting host species based on these two factors.
Conclusion
It seems evident that the two parasite species above would be worthy of further study to determine the reason why in this investigation they seemed to have host specificity for L. saxitilis. (Fig2) Evidence in this observation showed that it was not the size of the host or their particular (Fig3)habitat type that determined the infection. Hence another possible environmental factor may be influencing these particular parasites to infect L. saxitilis. There could possibly be factors such as temperature, desiccation, and salinity of the water that are influencing these results. It may become apparent with further study that there may well be some kind of host-parasite combination with their own set of rules associated with some other ecological and physiological factors. This may have laid the path to their possible co-evolution (Gorbushin and Lerakin 1999).
References:
A.M. Gorbushin and I.A. Lerakin , The effect of Trematode parthenitae on the growth of Onoba aculeus, Littorina saxtilis and Lobtudsata. Journal of Marine Biology (1999) 79: pp273-278
R.E Sorensen and D.J. Minchella, Snail-trematode life history interactions: past trends and future directions. Parasitology parasitology (2001) 123 S3-S18.
