Yunnan is an excellent place to compare the maintenance of fig-fig wasp mutualisms across latitudes, as several species have a large latitudinal span, extending from the tropics north to the subtropical Nujiang (Salween River) region. The reproductive phenologies of figs and fig wasps are affected significantly by climate.
Researchers from Xishuangbanna Tropical Botanical Garden (XTBG) compared the phenology of both figs and their associated wasps in tropical Xishuangbanna and subtropical Liuku. They aimed to understand how figs and fig wasps respond to seasonal changes in climate along a latitudinal gradient. They further wanted to see what factor(s) determine the northern limits of fig distributions in southwest China; and how climate change is likely to affect the fog –fig wasp mutualism.
They compared the phenologies of Ficus altissima, F. racemosa and F. semicordata in tropical Xishuangbanna (21°55′N) and subtropical Liuku (25°50′N), SW China, to understand what factors limit fig distributions near their northern limits.
All species produced synchronous crops of syconia in Xishuangbanna but production in Liuku was continuous, which may help maintain pollinator populations. However, in general, they found decreased fitness at the northern site: slower syconium development, so fewer crops each year; fewer seeds per syconium (two species); and fewer pollinators and more non-pollinators per syconium, so less pollen is dispersed.
The results suggest that changes in phenology, as a result of plasticity or genetic variation, have allowed some tropical fig species to extend their ranges polewards.
The study entitled “Latitudinal effects on phenology near the northern limit of figs in China” has been published in Scientific Reports.
PENG Yanqiong Ph.D Principal Investigator
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China