The AFLP (amplified fragment length polymorphism)technique was used to analyse the genetic diversity in four scallop species,Patinopecten yessoensis, Argopecten irradians, Chlamys nobilis and C. farreri. The genetic similarity indexes of these four species are 0.841 5, 0.786 3, 0.719 0 and 0.673 1, while Shannon diversity indexes are 43.52, 58.87, 80.16 and 92.83 ,respectively. As analyzed,the genetic diversities in two native species, i.e., C. farreri and C. nobilis, are higher than those in other two introduced species, A.irradians and P. yessoensis. The results also showed that C. nobilis and C. farreri shared the most common loci. The genetic distance indicated that C. nobilis and C. farreri are closely related. Moreover, out of 510 AFLP markers, 21 specific bands are found to distinguish the four species scallops and these markers may be applied to the specific germplasm characterization and molecular assistant classification in scallops.
Yucca baccata cheats in its obligate pollination/seed predation mutualism with yucca moths. Although all individuals use the pollination services of yucca moths, many individuals do not reciprocate in sustaining yucca moth larvae. Cheating is associated with the morphology of Y. baccata pistils. In Y. baccata , the apex of the ovary contains only inviable ovules, and there are two distinct flower types, one of which has twice as many potentially viable ovules as the other. Because yucca moths oviposit at the apex of Y. baccata ovaries, larvae in flowers with few viable ovules fail to encounter viable ovules and therefore perish. Inflorescences generally have just one flower type, implying that some individuals cheat whereas others maintain the yucca moth population. Our most surprising observation, however, is that although the proportion of cheaters should be low, over 70% of Y. baccata individuals cheat. We hypothesize that both density‐ and frequency‐dependent processes maintain a balance of cheaters and noncheaters in this system.
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