C. K. Yeo

Herbarium records do not predict rediscovery of presumed nationally extinct species

Rediscoveries of species previously thought to be extinct present a dilemma to conservation biology. On one hand, such instances offer the chance to change the course of events away from one that would have led to extinctions. On the other hand, public support for conservation may wane if scientists are frequently seen to overstate and prematurely declare extinctions. Recent studies have adopted a probabilistic approach to infer extinction, using sightings or collections and statistical models to calculate the chance that a species may still be extant. We conduct the first broad-scale test of such models using a recently compiled national red list and national herbarium collection records, including collections of presumed nationally extinct species made after the red list publication, which constitute “rediscoveries”. There was little evidence that the probabilities calculated by these models were associated with rediscoveries over a 3.5-year period. Current probabilistic models of extinction using sighting records could hence be inadequate for use with most natural history collection data.

Variation in reproductive output of Ficus superba despite aseasonal reproduction

Studies of Ficus reproductive phenology have focused on documenting its seasonality and dependence on meteorological factors. While there have been reports that duration of receptivity of syconia can be prolonged in response to pollinator limitation, the effect of pollination rate on the duration of phenological phases over a year has not been examined. Percentage of unpollinated syconia, number of foundresses per pollinated syconium, duration of receptivity, frequency of single-sex broods, crop size, frequency of parasitisation, persistence of ripe syconia, and mass abscission were recorded for Ficus superba at the crop level. Percentage of unpollinated syconia is significantly negatively correlated with the number of foundresses per syconium, and positively correlated with the duration of receptivity, and the persistence of ripe syconia. Despite the absence of sesonality in reproduction, the occurrences of receptive syconia and ripe syconia showed unimodal and bimodal peaks, respectively, owing to prolongment of these phases. This is attributable to meteorological factors, which are hypothesized to influence pollinator dispersal, or population dynamics, and thus pollination rate. This highlights the overlooked significance of pollinator, and possibly frugivore phenology in accounting for Ficus reproduction, and suggests that while reproduction may be aseasonal, reproductive potential may not be. Furthermore, crop size was shown to affect the number of foundresses per syconium, duration of receptivity, and persistence of ripe syconia. Possible adaptive value of producing crops of different sizes is discussed.

Pollination of Ficus elastica : India rubber re-establishes sexual reproduction in Singapore

Ficus elastica, otherwise known as India Rubber (although its geographical origins are unclear), was an important source of latex in the early 19th century and was widely cultivated in tropical Asia. Like all figs, F. elastica is dependent on tiny, highly specific wasps for pollination, and detailed studies based out of Singapore in the 1930s suggested that through the loss of its pollinator F. elastica was extinct in the wild. However, around 2005 wild seedlings of F. elastica began appearing in Singapore. We identified the pollinator as Platyscapa clavigera, which was originally described from F. elastica in Bogor in 1885. A visit to Bogor Botanical Gardens revealed that not only was F. elastica being pollinated by P. clavigera in the gardens, but there was clear evidence it had been reproducing naturally there over many decades. Although Singapore has a native fig flora of over 50 species, F. elastica went unpollinated for at least 70 years and probably from the time it was introduced during the 19th century. These observations illustrate the extraordinary specificity of this interaction and, through the fig’s ability to wait for its pollinators, demonstrates one way in which such highly specific interactions can be evolutionarily stable.