Cloning and Aggression among Sea Anemones Essay

Cloning and Aggression among Sea Anemones - Essay Example These clones rapidly spread out and form large aggregations of individuals exhibiting polymorphism. Individuals present in the center of clones are larger with gonads, and reproduce sexually. Individuals at the edge of the colony are smaller, with larger fighting tentacles (acrorhagi), being defensive in nature reproduce asexually. This division of labor allows individuals in the center to expend more energy on sexual reproduction and individuals on the edges of aggregations to expend their energy on developing large acrorhagi to fight the individuals of adjacent clones. Aggression is provoked when individuals on the circumference come into contact with genetically different clones. Acrorhagi, which are large projections loaded with nematysts located at the base of the tentacles, are used to sting, injure, and even kill members of the other clone. This inter-clonal fighting results in clear boundaries between adjacent aggregations. This aggressive behavior is fused on non-clone mates , as members of each clone can distinguish their own clone mates and do not attack them. Intraspecific competition of the inference sort has also been observed in experiments where two adjacent clones competed over the resource of space. The significance level for shore position, clonal/aclonal growth, and aggressiveness... Rare species were excluded for consistency and simply sharpen the focus of the present study. Study sites The samples were collected from two long north-south gradients extending from subarctic to subtropical latitudes.(Further details see L.Francis,1988,p.243) Assignment to categories The samples are categorized based on habitat, individual body size, clonal, aggressive nature. Statistical method The significance level for shore position, clonal/aclonal growth, and aggressiveness acting simultaneously is determined by using a multi-way G-test. In addition, Fisher's exact test with critical alpha levels corrected to compensate for multiple use of data is also used since some of the theoretically possible sets are though empty, is permissible, if conservative, to use [comparison wise error rate = 1 - ( 1 - )1/c, where c is the number of comparisons and is the desired level of confidence; Sidak, 1967, cited in SAS guide, 1985]. (For three sets of comparisons, a comparison wise error rate of 0.0165 is equivalent to an experimental error rate of 0.05.) Development of a model A geometric model is developed to predict the relative energy efficiency of interference as a function of increasing size: (1) for growth through isometric increase in size (simulated growth of an aclonal adult), and (2) for growth without increasing in height (simulated growth and spread of a compact, encrusting clone). Results Correlations From the observations, it was evident that overall distribution of species was uneven with respect to shore position, clonal/aclonal growth and aggressiveness. Tested separately, two of the three pair wise interactions were significant (for cloning vs. aggression and