Ecology

The behaviour of the beetle Stenus comma hunting three species of springtails was investigated. In almost half the attacks on prey, the beetle used its protrusible labium to catch the springtail. However, attacks using the labium were less successful when the springtail was large or was covered in scales or setae, as the prey item was more likely to become detached from the sticky tip of the labium. Thus the beetle was more likely to attack large springtails without using its labium.

Aim  The effects of logging and habitat degradation on the richness and abundance of small mammals in Asian rain forests are largely unknown. This work compares the species richness, dominance and evenness of small non-volant mammals between logged and unlogged forests, and assesses whether assemblage variability (β-diversity) is similar between forest types.Location  Southeast Asia, northern Borneo (Sabah, Malaysia), Sunda-shelf.Methods  We surveyed species-rich assemblages of small non-volant mammals in three unlogged and three logged forests for 2 years. At each forest site, we sampled a permanently marked transect and two additional sites in three trapping sessions. All analyses were performed at both levels to include the effects of local abundances and point estimates, separately from the relative abundances of species on a more regional scale.Results  We trapped a total of 1218 individuals of 28 species. Eleven common species accounted for 95% of all captures. Species richness and diversity were significantly higher in unlogged forest (27 species) than in logged forest (17 species). This was mainly attributable to the smaller number of rarely recorded species in logged forest (five compared with 16 in unlogged forest, with a total of fewer than 10 captures). However, all common species were present in both logged and unlogged forests, and our analyses revealed similar patterns of dominance, evenness and fluctuations in abundance. Hence overall assemblage composition in multivariate space did not differ greatly between forest types. Assemblages of Muridae and Tupaiidae showed similar population fluctuations in space and time, indicating that the ecology of these taxa may be partially driven by the same environmental factors.Main conclusions  Although species were distributed patchily within sites, analyses at local and regional scales revealed similar patterns in diversity and assemblage variability, suggesting that effects of forest modification did not differ extensively locally and regionally, but had a profound effect on rare species. Our results emphasize the importance and conservation value of logged forest stands that are able to hold a large proportion of the small mammals also found in unlogged forests. Rare and more specialized species are more vulnerable to forest degradation than commonly caught species, resulting in the complete loss, or a decrease in numbers, of certain groups, such as arboreal small mammals and Viverridae.

The oil palm, Elaeis guineensis, is a native of West Africa and is now extensively grown in south-east Asia. In 2005, the crop covered four million ha of Malaysia. We examined the arboreal ant fauna in two oil palm plantations that had been farmed with integrated pest management practices for at least 10 yr. Having cut and examined palm fronds from 595 and 503 palms in Borneo and Peninsular Malaysia respectively, we studied diversity in ant assemblages, analysed composition of ant mosaics by stepwise use of null-models, and explored the influence of exotic vs native species on community structure. Altogether we sampled 52 species of canopy ants, of which 23 species were shared between Borneo and Peninsular Malaysia. Seventeen species in Borneo and 24 species in Peninsular Malaysia accounted for 95% of all species occurrences (SOCs). Fortysix percent of all SOCs belonged to 12 tramp ant species with pan-tropical distributions. Forty percent of all SOCs were exotic ants. Six dominant species were found in Borneo, five in the Peninsula. The three most abundant species, Anoplolepis gracilipes, Oecophylla smaragdina and Technomyrmex albipes were dominant in both sites. Three dominants were invasive species that were found on more palms than the native group. Dominant tramp species coexisted with non-dominants more often and tolerated more species of non-dominant ants than native dominants. Null model analyses indicated that species were arranged in mosaics at both the Peninsular Malaysia and Borneo sites. Dominant species showed much less co-occurrence than expected by chance, pointing towards species segregation (even in presence of introduced, invasive species). Similar results were obtained for all species. Non-dominant ants were either positively associated with their dominants, or co-occurred randomly in the presence of dominant species. In contrast, ant assemblages on palms without dominants showed species segregation.

Aim  Ants (Hymenoptera/Formicidae) have strong influences on ecosystems especially in arid regions. However, little is known about ants of the vast steppe and desert regions of Central Asia. Here we provide the first comprehensive study of ant communities in Mongolia, conducted along a north-to-south gradient in climate. We examined ants’ distribution patterns, assessed the impact of climatic parameters on community structure and species diversity and investigated the influence of the corresponding communities of plants.Location  Mongolia (Central Asia).Methods  We observed 31,956 ants at seed baits at 11 study sites along a transect from steppe to Gobi desert for which we attained meteorological data (mean yearly precipitation: 197 to 84 mm). Extra sampling was conducted at sugar and protein baits and by the inspection of different microhabitats. Vegetation patterns of each plot were recorded. Statistical evaluation comprised ordination and correlation.Results  We observed 15 species of ants at seed baits. Three faunal complexes of ants could be distinguished by detrended correspondence analysis (DCA): (1) in steppe baits were dominated by Formica- and Myrmica-species, (2) in semi desert we found mostly species of Tetramorium, Myrmica, Proformica, Plagiolepis, and Leptothorax, and (3) in desert Cataglyphis aenescens and Messor aciculatus dominated, and Lasius was exclusively found there. Another 11 rare ant species were sampled by hand and at sugar baits. Altogether five ant species were new to the Mongolian fauna: Cardiocondyla koshewnikovi, Myrmica koreana, Myrmica pisarskii, Polyergus nigerrimus, and Proformica kaszabi. Assignment of taxa to functional groups showed that in steppe cold climate specialists dominated, in semi desert we found mainly opportunists, and in desert hot climate specialists. Several functional groups know from arid zones in other parts of the world were missing. In desert certain species were highly dominant. First DCA scores of ant- and plant-communities were highly correlated with each other and with climatic parameters. While plant species diversity was positively correlated with increasing northern latitude, ant diversity and ant species richness were not correlated with latitude and responded neither to precipitation, nor to any other climatic parameter. Semi desert was a transition zone between steppe and desert, with high species richness. Ant genus composition of the ecotone overlapped with both other regions. However, beta diversity between pairs of plots within this zone was low, indicating a small-scale mosaic pattern.Main conclusions  The ant communities in the Mongolian steppe and desert zones were strongly influenced by low temperatures and differed in many aspects from the ant fauna in other arid ecosystems, especially in terms of species richness, diversity of feeding guilds, and richness of functional groups.

1Non-volant animals in tropical rain forests differ in their ability to exploit the habitat above the forest floor and also in their response to habitat variability. It is predicted that specific movement trajectories are determined both by intrinsic factors such as ecological specialization, morphology and body size and by structural features of the surrounding habitat such as undergrowth and availability of supportive structures.2We applied spool-and-line tracking in order to describe movement trajectories and habitat segregation of eight species of small mammals from an assemblage of Muridae, Tupaiidae and Sciuridae in the rain forest of Borneo where we followed a total of 13 525 m path. We also analysed specific changes in the movement patterns of the small mammals in relation to habitat stratification between logged and unlogged forests. Variables related to climbing activity of the tracked species as well as the supportive structures of the vegetation and undergrowth density were measured along their tracks.3Movement patterns of the small mammals differed significantly between species. Most similarities were found in congeneric species that converged strongly in body size and morphology. All species were affected in their movement patterns by the altered forest structure in logged forests with most differences found in Leopoldamys sabanus. However, the large proportions of short step lengths found in all species for both forest types and similar path tortuosity suggest that the main movement strategies of the small mammals were not influenced by logging but comprised generally a response to the heterogeneous habitat as opposed to random movement strategies predicted for homogeneous environments.4Overall shifts in microhabitat use showed no coherent trend among species. Multivariate (principal component) analysis revealed contrasting trends for convergent species, in particular for Maxomys rajah and M. surifer as well as for Tupaia longipes and T. tana, suggesting that each species was uniquely affected in its movement trajectories by a multiple set of environmental and intrinsic features.Non-volant animals in tropical rain forests differ in their ability to exploit the habitat above the forest floor and also in their response to habitat variability. It is predicted that specific movement trajectories are determined both by intrinsic factors such as ecological specialization, morphology and body size and by structural features of the surrounding habitat such as undergrowth and availability of supportive structures.We applied spool-and-line tracking in order to describe movement trajectories and habitat segregation of eight species of small mammals from an assemblage of Muridae, Tupaiidae and Sciuridae in the rain forest of Borneo where we followed a total of 13 525 m path. We also analysed specific changes in the movement patterns of the small mammals in relation to habitat stratification between logged and unlogged forests. Variables related to climbing activity of the tracked species as well as the supportive structures of the vegetation and undergrowth density were measured along their tracks.Movement patterns of the small mammals differed significantly between species. Most similarities were found in congeneric species that converged strongly in body size and morphology. All species were affected in their movement patterns by the altered forest structure in logged forests with most differences found in Leopoldamys sabanus. However, the large proportions of short step lengths found in all species for both forest types and similar path tortuosity suggest that the main movement strategies of the small mammals were not influenced by logging but comprised generally a response to the heterogeneous habitat as opposed to random movement strategies predicted for homogeneous environments.Overall shifts in microhabitat use showed no coherent trend among species. Multivariate (principal component) analysis revealed contrasting trends for convergent species, in particular for Maxomys rajah and M. surifer as well as for Tupaia longipes and T. tana, suggesting that each species was uniquely affected in its movement trajectories by a multiple set of environmental and intrinsic features.

... Worker size and seed size selection in 'seed'-collecting ant ensembles (Hymenoptera: Formicidae) in primary rain forests on Borneo Martin Pfeiffer ∗1 , Jamili Nais† and K. Eduard Linsenmair‡ ... Page 2. 686 MARTIN PFEIFFER, JAMILI NAIS AND K. EDUARD LINSENMAIR ...

Journal of Tropical Ecology (2007) 23:35–43. Copyright © 2007 Cambridge University Press doi:10.1017/S0266467406003804 Printed in the United Kingdom ... Impact of rain-forest logging on helminth assemblages in small mammals ... Konstans Wells ∗1 , Lesley R. Smales † , ...

... In each run we calculated the mean Pianka index (Pianka 1973) from 30 000 iterations. The two most important randomization algorithms (RAs) RA 3 and RA 4 are described in Winemiller & Pianka (1991) and Albrecht & Gotelli (2001). ...

1. Deceptive species are a characteristic trait of insect–plant mutualisms. Deception of pollinators is essential for reproduction in diverse plant species; however, mimicry in seed dispersal is almost unknown. Myrmecochory, the dispersal of diaspores by ants, is a mutualism in which the elaiosome, a lipid-rich seed appendage, works as an ant reward. This coevolved interaction may be exploited by cheating, non-rewarding diaspores that mimic elaiosomes.2. Our study assesses the impact of the morphology and fatty acid composition of diaspores on ant dispersal in rewarding and cheating myrmecochores and non-myrmecochorous species. Four elaiosome types (defined by Sernander 1906) were included in our research: the ‘Viola odorata type’, with a clearly defined elaiosome, the similar but diplochorous ‘Euphorbia type’ with an additional ballistic dispersal of diaspores, and the ‘Puschkinia’ and ‘Hepatica’ types, which we classify as ‘cheaters’ as they mimic ant rewards by chemical cues.3. We tested the influence of morphology, chemical composition of diaspores and presence of rewards on removal rates of diaspores, dummies impregnated with seed extracts and pure fatty acids and scent-standardized diaspores in a population of Formica polyctena ants with 10 European spring ephemerals, mostly Ranunculaceae. The main free fatty acids of diaspores were identified by gas chromatography and mass spectrometric analysis.4. Removal rates of diaspores and dummies treated with seed extracts were significantly influenced by their fatty acid composition. Discriminant function analysis confirmed oleic acid as the main trigger substance eliciting seed-removal behaviour by ants in most species. Oleic acid content and removal rates differed among elaiosome types and were highest in rewarding myrmecochores, lower in cheaters and smallest in non-myrmecochorous seeds. Removal rates of scent-standardized diaspores did not differ among mutualists and cheaters suggesting a selective pressure for morphological adaptation and were lowest in non-myrmecochorous species, thus corroborating an influence of diaspore morphology on ant-removal patterns.5. For the first time, we demonstrate chemical mimicry in myrmecochory as a means of seed dispersal. Evolutionary stability of the ant–seed mutualism is maintained by the ability of ants to discriminate between certain types of rewards and to respond with differential diaspore distribution rates.

Knowledge of how animals move through the environment is important for predicting effects of habitat change on faunal distributions. Logging of tropical rain forests produces habitat changes on multiple scales that may affect movement and habitat use by small mammals. To ...