Predatory marine snails and their prey provide a unique look at many aspects of predation events, allowing behavioral inference and studies of coevolution. This study examines differential predation patterns, rates, and success of two co-occurring gastropod predator families which drill two co-occurring species of Turritella (Turritellidae: Gastropoda) in the Gulf of California. Both naticid and muricid predators, identified by the shapes of their respective boreholes, attacked the thinner-shelled Turritella leucostoma more frequently than the thicker-shelled Turritella gonostoma. Both species were drilled more frequently and more successfully by naticid, as compared to muricid, predators. Naticids drilled prey in the 40- to 70-mm size class most frequently. Prey over 100 mm in length were relatively safe from all drilling predators. Predator size (estimated by borehole diameter) in naticids was correlated with prey size in both species, but for a given-sized prey, predators on T. gonostoma were proportionally larger. There was no size correlation for muricid predators. Unsuccessful attempts (incomplete drilling) were started on the suture more often than were completed holes, for both predator families on both prey species. Naticids began drilling T. leucostoma on the suture significantly less than expected by chance. We looked for possible changes over evolutionary time by analyzing prey shells from Pleistocene and Recent storm deposits. We found no evidence of change in any aspect of implied predatory behavior over the past 100 k.y.

Logged forests form an increasingly large proportion of tropical landscapes but disproportionately few studies have studied the impact of forest disturbance, e.g. lightly vs. heavily logged, on tree and seedling communities simultaneously. We sampled all trees (on 1 ha) and all recently germinated seedlings (on 90 m2) in three lightly and three heavily logged sites in each of the following three East African tropical forests: Budongo Forest and Mabira Forest in Uganda and Kakamega Forest in Kenya. We analysed species richness, diversity, abundance and community composition of late- and early-successional trees and seedlings. We recorded no difference in species richness or diversity of late-successional or early-successional trees between lightly and heavily logged sites. However, the abundance of late-successional species was lower in heavily than lightly logged sites. Moreover, there was no difference in species richness or diversity of trees among the three forests. Yet, abundances of late-successional trees were higher in Budongo Forest than in Mabira Forest and Kakamega Forest. Species richness, diversity and abundance of seedlings did not differ between lightly and heavily logged sites. Only the abundance of seedlings of late-successional species differed among the forests with more individuals in Budongo Forest than in Mabira Forest. This was corroborated by non-metric multidimensional scaling (NMDS) showing clear differences in composition of tree and seedling communities among the three forests. Thus, both, the tree and seedling communities differed significantly among the three forests but not between lightly and heavily logged sites.

Dioecious plant species differ in floral morphology and rewards between females and males. Pistillate flowers on female plants often lack pollen and can be less attractive to pollinators, which can have consequences for the visitation rates of the sexes. We studied the pollination ecology of the dioecious tree Commiphora harveyi in a coastal scarp forest in eastern South Africa. Floral display, visiting insect species, visitation rate and natural fruit set were recorded. Additionally, we pollinated flowers by hand to determine experimental fruit set. We found that male trees had more and larger flowers per inflorescence than female trees. Both sexes produced nectar in low amounts. During 203.5 h of observation we recorded 28 insect species visiting the flowers. No difference in mean visitation rate (0.20 visits per flower h−1) was recorded between the sexes. The daily and seasonal pattern was similar between the sexes. The natural fruit set was low (3.8%) and increased significantly with hand-pollination (45.5%), an indication of pollen limitation. We compared our results with the pollination ecology of C. guillauminii in Madagascar, a dioecious tree species on an island with a depauperate pollinator fauna. This comparison revealed a similar pattern with low visitation rates, low insect diversity and low fruit set, suggesting that this pattern may be more common in dioecious tree species than previously reported in the literature.

In dioecious plant species differences in morphology and resources between female and male flowers can have consequences for flower visitation rates. Female flowers sometimes lack pollen and can be less attractive to pollinators than male flowers. We studied the pollination ecology of the dioecious tree Commiphora guillauminii in a dry deciduous forest in western Madagascar. We recorded floral display, visiting insect species and visitation rates for female and male trees. The results showed that female trees produce significantly larger but fewer flowers per inflorescence than male ones. Number of flowers per tree did not differ between the sexes. During 270 observation-hours we observed 17 insect and two bird species visiting the flowers. Mean visitation rates of male flowers were 6.1 times higher than those of female flowers (1.07 vs. 0.18 visitors per flower h−1). Visitation rates to female and male trees showed similar daily and seasonal patterns. Fruit set (2.9%) was low, which could have been caused by pollinator or pollen limitation. This study suggests that dioecy may pose a risk for fruit set and, potentially, reproductive success for plant species with depauperate pollinator faunas on islands such as Madagascar.

For many tropical forests a tendency for fruit production to fluctuate seasonally has been established, with pronounced peaks of abundance and periods of fruit scarcity during which a few important resources maintain frugivore communities. However, there is a lack of studies in subtropical forests on community phenology and on the identification of important resources. In this study, community-wide fruit availability and its use by the local frugivore community was investigated in the subtropical coastal dry forest of Oribi Gorge Nature Reserve, South Africa over 13 mo from July 1997 to July 1998. Along 19.5 km of phenology trails, 940 individuals of 96 plant species bearing fleshy fruits were monitored twice per month and fruit-eating animals observed. Although some fruit was available all year round richness of both fruiting species and fruit abundance showed a seasonal pattern with peaks at the end of August to beginning of October (i.e. before the rainy season) and March to May (i.e. after the rainy season). Periods of fruit scarcity were found in July and August (i.e. during the long dry season) and in November and December (i.e. during the rainy season). Fruits of 23 plant species were observed being eaten by 18 species of bird and two of monkey. Highest animal numbers were attracted by Ficus thonningii, a species that fruited asynchronously during most of the year and during periods of fruit scarcity, and provided high overall fruit biomass. The importance of this species as a potential keystone resource for the frugivore community is discussed.