Barnacles are mostly sessile, hermaphroditic, internal-fertilizing and usually non-selfing crustaceans. They have the longest penis length, relative to body length, among all organisms. Because of their immobility, barnacles have to extend penes to reach mates and transfer the sperm. The longer the penis the more mates they can reach. However, maintaining long penes may be costly. How do barnacles allocate the reproductive investment and adjust the length of penes? Previous researches indicated that wave actions influenced the penis length of barnacles. Here we explore if biological factors are also involved in determining the penis length. Our hypotheses are that the penis length of Balanus amphitrite may be determined by (1) the presence of neighbors, (2) neighbor numbers, and (3) neighbor distance. Experimental results indicate that the neighbor distance could influence the penis length of B. amphitrite, and the penis length increase with increasing distance of neighbors. The neighbor numbers were not found to influence the penis length. In the treatment of lone individuals, the penis lengths first increased and then decreased, and they are significantly shorter than those in the treatment with neighbors. When neighbors exist, B. amphitrite detects the density by distance of neighbors. The greater the distance to neighbors, the lower the densities of neighbors. Because of the mates are enough to mate, the penes length decrease with increasing density to save cost. When neighbors do not exist, B. amphitrite may save cost by decreasing or not investing pens length . Our result shows that the plasticity of the penis length of B. amphitrite is an adaptation by natural selection.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0825110-154117 |
| Date | 25 August 2010 |
| Creators | Yu, Hui-ying |
| Contributors | Jin-hua Cheng, Keryea-yea Soong, Shyh-min Choa, Chen-chih Kao |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0825110-154117 |
| Rights | unrestricted, Copyright information available at source archive |
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