西双版纳地区4种榕树果实的资源分配及其种子萌发特性

为了解榕树果实的资源分配和种子萌发特征,对西双版纳地区的垂叶榕(Ficus benjamina)、高山榕(F.altissima)、聚果榕(F.racemosa)和无柄雅榕(F.concinna)的果实营养、繁殖资源分配,以及种子萌发特性进行了研究。结果表明,4种榕果的营养分配存在差异,榕果重的种类果肉亦多,榕果大者果腔较大,且种子数量较多,但雄花和榕小蜂数量不一定多。榕果分配给雌性功能及雄性功能繁殖的小花比例也不相同,聚果榕在雌性功能上的分配显著大于雄性功能,其它3种榕果则分配于雄性功能的资源比雌性功能的多,但程度不同。此外,4种榕树的种子大小及重量存在显著的种间差异,以至于影响到种子的萌发率及根茎生长,果实最大的聚果榕种子最多,萌发率高,但由于种子最小,其根茎生长缓慢且短;果实适中的垂叶榕和高山榕种子较大,不但萌发率较高,其根茎生长也较快;果实和种子都小的无柄雅榕,种子萌发率低,根茎生长慢。生长在水热环境好的榕树比生长在相对贫瘠环境的榕树,由于极少面临水热光照等限制,更容易进化出较小的种子,萌发能力和速度也相对较差。这说明不同生境中榕树进化出了不同的繁殖分配机制及资源利用策略来适应环境变化。     

鸡嗉子榕内传粉小蜂与非传粉小蜂的繁殖稳定共存机制研究

【目的】榕-蜂系统是自然界协同进化和互利共生的典型模型,榕-蜂之间如何实现繁殖分配从而实现稳定共存一直是倍受研究者关注的问题,但对传粉小蜂和非传粉小蜂的繁殖稳定共存研究较少。【方法】本文选取分布在西双版纳地区的雌雄异株榕树鸡嗉子榕Ficus semicordata的雄果,通过对榕果内唯一的传粉小蜂Ceratosolen gravelyi Grandi以及4种非传粉小蜂Philotrypesis dunia Joseph,Apocrypta sp.,Platyneura sp.,Sycoscapter trifemmensis Joseph的产卵时序进行了观察,并对5种小蜂的种群数量进行统计,以及对每种小蜂产卵小花的空间分布、瘿花体积等特征进行了研究。【结果】发现:5种小蜂在产卵时间上存在分离,且传粉小蜂的种群数量远大于其他4种非传粉小蜂的种群数量之和。5种小蜂的瘿花特征也存在差异:瘿花的子房大小不同,且花梗长度即分布空间也有差异,传粉小蜂最接近果腔而非传粉小蜂则更多地利用中层和内层的小花。【结论】结果说明在鸡嗉子榕有限的空间内,5种小蜂通过产卵时间和生长空间的分离,实现了减少竞争以及长期共存的特征,维持了榕-蜂系统的稳定性。     

夜间低温后日间光照对海桐和榕树叶片的光抑制以及光系统Ⅱ功能的影响

夜间低温导致海桐和榕树叶片光系统Ⅱ(PSⅡ)最大光化学效率(Fv/Fm)、PSⅡ光合电子传递量子效率(φPSⅡ)、天线转化效率(F'v'/Fm')、非光化学猝灭系数(NPQ)降低,其后日间光照先引起海桐叶片Fv//Fm、ΦPSⅡ、F'v'/Fm'稍微降低,其后又逐渐得到恢复,但NPQ却表现出相反趋势;夜间低温及随后的日间光照并未对海桐叶片光化学猝灭系数(qP)和初始荧光强度(Fo)产生影响.夜间低温后日间光照进一步引起榕树叶片Fv/Fm、ΦPSⅡ、Fv'/F'm、qp、NPQ下降,在午后光照减弱后仍不能得到恢复.     

夜间低温后日间光照对海桐和榕树叶片的光抑制以及光系统II功能的影响

夜间低温导致海桐和榕树叶片光系统II(PSII)最大光化学效率(Fv/Fm)、PSII光合电子传递量子效率(ΦPSII)、天线转化效率(Fv'/Fm')、非光化学猝灭系数(NPQ)降低,其后日间光照先引起海桐叶片Fv/Fm、ΦPSII、Fv'/Fm'稍微降低,其后又逐渐得到恢复,但NPQ却表现出相反趋势;夜间低温及随后的日间光照并未对海桐叶片光化学猝灭系数(qP)和初始荧光强度(Fo)产生影响。夜间低温后日间光照进一步引起榕树叶片Fv/Fm、ΦPSII、Fv'/Fm'、qP、NPQ下降,在午后光照减弱后仍不能得到恢复。     

Chemical composition of volatiles from the syconia of Ficus microcarpa and host recognition behavior of pollinating fig wasps

Aims Chemical communication plays a key role in host plant recognition of pollinators. There are two recognized types of chemical communication between syconia and their pollinating fig wasps: one is “generalization”, of which the wasps respond to the relative ratio of multiple compounds, and the other is “specialization”, of which the key signal is a single uncommon, possibly unique, compound. The aims of this study were to identify the chemical composition of volatiles from the syconia of Ficus microcarpa at different developmental phases, and to determine if the signaling between F. microcarpa and its pollinating fig wasp, Eupristina verticillata, is of generalized type, or of specialized type.Methods The volatiles from syconia of F. microcarpa were extracted using solid-phase micro extraction (SPME) at different developmental phases (pre-female, female (before and after pollination), interfloral, male and postfloral phases) and the chemical compounds were identified by gas chromatography mass spectrometry (GC-MS). We then tested the behavioral responses of E. verticillata to fresh syconia at different developmental phases using two-choice olfactometers.Important findings There were 21 volatile compounds identified from the syconia at different developmental phases, which were mainly fatty acid derivatives, terpenoids and aromatic compounds. The components of the volatiles apparently differed among the developmental stages. The contents of terpenoids declined, but the contents of fatty acid derivatives increased, from before the pollination to after the pollination. Especially, the characteristic compounds of 2-heptanone and 3-octanone before the pollination disappeared, D-limonene decreased after the pollination, but copanene, cyclohexane and 2-hexenal increased. The results of the two-choice olfactometer experiment showed that the pollinating fig wasps had higher selection ratio to chemicals found in the female phase syconia than those in other phases; whereas the volatile compounds from the male phase syconia had the function pushing the pollinating fig wasps to leave the natal syconia so that there existed the “push-pull” responses by fig wasps to volatiles released by their host syconia. We conclude that there are multiple chemical compounds playing the roles in host recognition of pollinating fig wasp E. verticillata. The mutualistic relationship between F. microcarpa and E. verticillata is maintained by the chemical communication of “generalization” strategy.