Reproductive biology of theIlexspecies (Aquifoliaceae) in Hong Kong, China

Abstract

Fourteen wild species of shrubs and trees in the dioecious genus Ilex occur in Hong Kong (228N, 1148E). All species flowered and formed fruits once each year. Sex ratios at flowering were male biased in all but one large population studied and, in most cases, this bias could not be explained by earlier flowering in males or higher female mortality. Apis cerana accounted for >87% of flower visits in all species and there was a significant positive relationship across species between the number of visits per flower per hour and the estimated mean number of flowers on a plant. The large green fruits of Ilex chapaensis Merr. were consumed only by masked palm civets, Paguma larvata, while the red or black fruits of other species were consumed by birds. The rate of fruit removal across species was positively related to sugar content and negatively related to phenolic and saponin contents. The mean number of pyrenes per fruit was 4.0-6.2 and the mean percentage of pyrenes containing seeds was 49%-90%. Most embryos were immature (heart shaped) at fruit maturity, but <50% of embryos developed further in some species. Floral investment was 0.93-5.84 times higher in male plants, but total reproductive investment was 0.62-8.3 higher in females. Résumé :On retrouve 14 espèces d'arbustes et d'arbres sauvages du genre dioïque Ilex, à Hong Kong (228N, 1148E). Toutes ces espèces fleurissent et fructifient une fois par année. À l'anthèse, les ratios sexuels ont un biais mâle chez toutes sauf une grande population étudiée et, dans la majorité des cas, ce biais ne peut pas être expliqué par une floraison plus hâtive chez les mâles ou une mortalité plus importante chez les femelles. L'Apis cerana réalise >87 % des visites chez l'ensemble des espèces, et on observe une corrélation positive significative, chez l'ensemble des espèces, entre le nombre de visites par fleur et par heure et le nombre moyen estimé de fleurs sur un plant. Les gros fruits verts de l'Ilex chapaensis Merr. sont consommés uniquement par la civette palmiste masquée, Paguma larvata, alors que les fruits rouges ou noirs des autres espèces sont consommés par les oiseaux. Le taux de prélèvement des fruits, chez l'ensemble des espèces, est positivement relié à la teneur en sucre et négativement relié aux teneurs en phénols et en saponine. Le nombre moyen de pyrènes par fruit est de 4,0-6,2, et le pourcentage moyen des pyrènes contenant des graines est de 49 % -90 %. La plupart des embryons sont immatures (cordiformes) à la maturité des fruits, mais <50 % se sont développés plus complètement chez certaines espèces. L'investissement floral est 0,93-5,84 plus élevé chez les plantes mâles, mais l'investissement reproductif total est 0,62-8,3 plus élevé chez les femelles.

Seed dispersal in Hong Kong, China: past, present and possible futures

“…Fruit flesh also contains compounds that function in defense against microbes or invertebrates, and these may make them less attractive to vertebrate frugivores. The rate of fruit removal by birds across 9 species of Ilex in Hong Kong was positively related to the sugar content of the fruit flesh and negatively related to the content of phenolics and saponins (Tsang & Corlett 2005). Different fruit species in Hong Kong have evolved different solutions to the problem of defense, as shown by observations of fruit persistence under both natural conditions and when frugivores are excluded by mesh bags (Tang et al 2005).…”

“…There is less information available for P. larvata in Hong Kong because its feces are harder to locate (Wan 2009), but studies in central China (Zhou et al 2008a) and Japan (Matsuo & Ochiai 2009) suggest it prefers fruit when this is available. It was the only species seen to eat the large green fruits of Ilex chapaensis in Hong Kong, harvesting them directly from the tree and dropping many seeds from the mouth (Tsang & Corlett 2005). Chinese ferret badgers, Melogale moschata, are the most widespread small carnivores in Hong Kong (Pei et al 2010).…”

Seeds and the City: The Interdependence of Zoochory and Ecosystem Dynamics in Urban Environments

“…When the exclusive seed disperser is extirpated and not replaced functionally by other species, then the recruitment of plant species that rely on that disperser will completely subside. The absence of animal-dispersed plant species from otherwise suitable urban habitats (i.e., secondary urban forests) would suggest such seed dispersal failure (Tsang and Corlett, 2005). The local extinction of a seed disperser might be particularly disruptive in fragmented landscapes (Rodríguez-Cabal et al, 2007), such as urban areas, since animal species richness may be reduced and fragment isolation may limit disperser replacement by animals from other fragments.…”

“…In fact, in Sydney, Australia, invasive fruit species with similar seed size as native species were removed by ants at a similar rate (Grimbacher and Hughes, 2002). Seeds of a large number of native and alien species have been observed in the scats of urban canids, viverrids, and mustelids (Tsang and Corlett, 2005;Corlett, 2011;D'hondt, 2011;Tsuji et al, 2011;Cancio et al, 2017), suggesting that omnivorous predators are also important dispersers in urban areas. A disperser preference for alien plants may also disrupt the dispersal of some native species (Bermejo and Guitian, 2000;López-Bao and González-Varo, 2011;Rost et al, 2012), by dispersing alien seeds instead of native seeds.…”

Forensic value of pollen from ornamental indoor plants

“…Ilex sp. (Tsang & Corlett 2005) was placed in the entrance hall. With the exception of Euphorbia leuconeura, all these plants are entomophilous.…”