Gender and phase expression in Lloydia serotina: A query into ecological and evolutionary implications.

摘要

Lloydia serotina, the alplily, is an alpine perennial common to alpine and arctic regions throughout the Northern Hemisphere. It has been described as androdioecious, but upon examination, demonstrates a more labile expression system, likely andromonoecious---a labile gender system previously undescribed. By examining when gender determination is made and whether size and the environment I influence gender expression, I can begin to address whether this system could be adaptive in the alpine environment.; Many alpine perennials are known to preform structures one to several years m advance of their use. In L. serotina, preformation of flowers may mean that floral gender is determined prior to the season of presentation. Dissections indicated that, while the inflorescence is initiated two years prior to function and all structures are formed one year prior, determination is not likely made until the spring of floral expansion.; Plant size appears to be the most important factor in gender determination in the alplily. Larger plants are more likely to have hermaphrodite flowers and to produce more flowers in general, predicted by the size advantage hypothesis. Observational soil and topographic data did not indicate any influence on gender. However, soil nutrients positively affect phase expression (an increase in flower number and hermaphroditic flowers), while herbivory negatively affected expression in manipulated plots.; Because of the supposed severity of the alpine environment, it might appear maladaptive for a plant to have its reproductive capabilities affected by size and the environment. However, non-labile plants may experience increased mortality when seed is produced because of a loss of resources needed for survival. A labile plant reduces this risk by eliminating maternal function at periods of high risk for resource-caused mortality and reallocating these resources to survival and growth. If a plant is able to discern the local environment and only produces ovules when seed establishment has a higher chance of success, seeds are less likely to be wasted and the percent of successful seedling establishment would be high compared to non-labile forms. Both of these factors would contribute to maintenance of labile expression in the alplily.