Research Article
Relationships between roost preferences, ectoparasite density, and grooming behaviour of neotropical bats
- Hannah M. ter Hofstede, M. Brock Fenton
-
- Published online by Cambridge University Press:
- 20 July 2005, pp. 333-340
-
- Article
- Export citation
-
Evidence suggests that behavioural defences, such as habitat selection and grooming behaviour, have evolved in animals in response to the costs associated with ectoparasites. Bat fly and mite densities were compared among wild-caught bats in Belize with different roosting preferences (cavity, foliage, or both), and grooming behaviour was analysed for bat species with high and low ectoparasite density. Ectoparasites of bats were removed using forceps, and bat grooming behaviour was recorded with a camcorder. Because bat flies pupate on the surface of host roosts, bats that use cavity roosts (a sheltered environment for the pupae) were predicted to have higher densities of bat flies than those that use foliage (exposed environment). Cavity-roosting species generally had higher densities of bat flies and mites, although the relationship was more evident for bat flies. The grooming behaviour of bats was predicted to differ among species with high or low ectoparasite densities. Although there was no difference in the frequency of grooming behaviours for individuals with and without bat flies, there were differences in grooming behaviour at the species level. Bat species with high ectoparasite densities scratched more than those with low ectoparasite densities. These results suggest that ectoparasite densities and grooming behaviour are related to roosting preferences in bats.
Phylogeny, phylogeography, and geographic variation of Sylvisorex howelli (Soricidae), an endemic shrew of the Eastern Arc Mountains, Tanzania
- William T. Stanley, Link E. Olson
-
- Published online by Cambridge University Press:
- 20 July 2005, pp. 341-354
-
- Article
- Export citation
-
The Eastern Arc Mountains of eastern Africa are notable for the high levels of endemism exhibited by various forest-dwelling organisms of this ancient montane archipelago. There has been virtually no assessment of the variation among populations of small mammal species living on these unique mountains, but recent faunal surveys have produced sufficient material to initiate such studies. Cranial morphometric and DNA sequence data were examined from six populations of Sylvisorex howelli Jenkins, 1984, an endemic shrew found in several different massifs of the Eastern Arc Mountains, to assess variation across the archipelago in the context of various hypotheses of historical biogeography. Twenty-two cranial measurements were analysed using principal components analysis. Age classes (based on tooth wear) and sex had little effect on the variation exhibited by the variables studied. Overall, specimens of S. howelli from the East Usambara Mountains are smaller than specimens from other known populations. The mitochondrial ND2 and 12S rRNA genes from representatives of each montane population of S. howelli in addition to several crocidurine taxa from eastern Africa and three soricine outgroup species were sequenced to assess phylogenetic relationships among these taxa. Neither maximum likelihood, maximum parsimony, nor Bayesian analyses support monophyly of the genus Sylvisorex, but S. howelli populations were consistently recovered as a well-supported clade. Over 40 individuals of S. howelli from six disjunct montane ranges, comprising the entire known distribution of the species, were sequenced for 504 base pairs of ND2 to investigate phylogeographic patterns. Phylogenetic analysis recovered six reciprocally monophyletic haplotype clades grouped by locality. Branch lengths are consistent with relatively long periods of isolation among populations from the Uluguru, Ukaguru, Nguru, Nguu, East Usambara and West Usambara Mountains, with low levels of diversity observed within each population. These results are interpreted within the historical context of the Eastern Arc Mountains.
Ecomorphological analysis of the masticatory apparatus in the seed-eating bats, genus Chiroderma (Chiroptera: Phyllostomidae)
- Marcelo R. Nogueira, Leandro R. Monteiro, Adriano L. Peracchi, Alexandre F. B. de Araújo
-
- Published online by Cambridge University Press:
- 20 July 2005, pp. 355-364
-
- Article
- Export citation
-
Recent data have shown that owing to their seed-predator capacity Chiroderma doriae and Chiroderma villosum trophically depart from all previously studied species within the canopy fruit-bat ensemble. In this paper, the hypothesis that morphological adaptations related to granivory have evolved in these bats is investigated and discussed. A canonical variate analysis was used to search for possible divergent trends between the masticatory apparatus of Chiroderma and other stenodermatines currently recognized in the same ensemble. A total of 142 specimens representative of eight species was included in the analysis. Species of Chiroderma can be discriminated from all other species in the sample based on the increased development of masseter-related variables (height of the anterior zygomatic arch, masseter moment arm, and masseter volume), which, in conjunction with other morphological characteristics (dentition and gape angle) discussed herein, corroborates the evolution of durophagy in this group. A complementary analysis based on a Mantel test revealed that the pattern of morphological differentiation that emerged from the canonical variate analysis does not agree with the one expected based solely on the phylogenetic relationships adopted for the canopy fruit-bats studied here. This result is consistent with the hypothesis that morphological adaptations related to granivory have evolved in Chiroderma.
Home range of giant anteaters (Myrmecophaga tridactyla) in the Pantanal wetland, Brazil
- Ísis Meri Medri, Guilherme Mourão
-
- Published online by Cambridge University Press:
- 20 July 2005, pp. 365-375
-
- Article
- Export citation
-
To obtain data on home range, movements, activity and habitat use by giant anteaters Myrmecophaga tridactyla, seven animals were captured, radio-collared and monitored from March to December 2001 in a 104-km2 study area in the Pantanal wetland, Brazil. Four of five males used areas that covered 4.0–7.5 km2 (5.7±1.7 km2), and one of two females monitored occupied a larger area (11.9 km2) than the males, but none of the curves of cumulative area unequivocally reached the asymptote. Generally, there was considerable overlap among individual areas used. The home-range estimates were calculated using the 100% minimum convex polygon, and 95% adaptive kernel methods. The areas used by the giant anteaters in the Pantanal wetland were larger than home ranges of giant anteaters in the Serra da Canastra National Park, Brazil. The habitat types were generally used in the same order as they occurred in each home range. Two giant anteaters previously monitored with VHF radio-telemetry were subsequently tracked with a modified global positioning (GPS) system in different periods. The modified GPS acquired data on activity and habitat use for c. 9 days. Giant anteaters did not show a similar pattern of habitat use during the period of study using the modified GPS unit, but their activity patterns were similar. One of the ranges recorded over 9 days with this method was larger than the range obtained over 252 days by standard VHF radio-telemetry.
Long-term costs of using heavy shells in terrestrial hermit crabs (Coenobita compressus) and the limits of shell preference: an experimental study
- José Luis Osorno, Jorge Contreras-Garduño, Constantino Macías-Garcia
-
- Published online by Cambridge University Press:
- 20 July 2005, pp. 377-383
-
- Article
- Export citation
-
Terrestrial hermit crabs use mollusc shells to protect their soft bodies from predation and desiccation, but their use is costly. The energetic short-term cost of using shells has been demonstrated, yet this could theoretically be overcome by increasing feeding rate or food quality. In the long term, shells have the potential to constrain growth, which may in turn have a negative effect on fitness. Thus crabs should choose the lightest (least expensive to carry) shell amongst those of a size that permit growth. Since in nature lighter shells are also thinner-walled, these may provide insufficient protection from predation or desiccation, facing the crabs with a trade-off between protection and growth. This potential trade-off was investigated in the terrestrial hermit crab Coenobita compressus. Crabs were individually maintained in captivity for a variable period of between 1 and 7 months, during which light or heavy replicates of the preferred shell were available. In a second experiment, crabs were given a choice between a thick (and heavy) or a thin (and light) shell. In addition, the resistance and water retention capacity of thin and thick shells was compared. As predicted, crab growth was negatively correlated with the weight of the shell used, but crabs rejected the thin (light) shells. Thin shells were more likely to break when crabs used the normal ‘rolling’ behaviour in response to perceived threats. In addition, thin shells lost water at a faster rate than thick ones. Since two putative functions of shell use in terrestrial hermit crabs are protection against predation and against desiccation, it is inferred that the preference for shells of intermediate weight in C. compressus results from a balance between the need to grow and the cost of carrying a brittle shell that is not sufficiently water tight.
The inguinal macroglands of the frog Physalaemus nattereri (Leptodactylidae): structure, toxic secretion and relationship with deimatic behaviour
- R. Lenzi-Mattos, M. M. Antoniazzi, C. F. B. Haddad, D. V. Tambourgi, M. T. Rodrigues, C. Jared
-
- Published online by Cambridge University Press:
- 20 July 2005, pp. 385-394
-
- Article
- Export citation
-
Amphibian skin is characterized by the presence of mucous glands, related to cutaneous breathing, reproduction and water balance, and granular glands, related to the production of toxins used in defence. In some species the granular glands can form accumulations in certain regions of the body. This is the case for inguinal macroglands of the leptodactylid frog Physalaemus nattereri, where these structures form a pair of black discs associated with deimatic behaviour. The morphology of the inguinal macroglands and their secretion were studied in this species and correlated to deimatic behaviour. The inguinal macroglands are formed from elongated granular glands that, in contrast with the granular glands of the rest of the skin, have small spherical granules with a proteinic content. In the dermis of the whole body, except for the inguinal macroglands and the inguinal region, a well-developed calcified dermal layer is observed. During deimatic behaviour these macroglands discourage a potential predator from attacking, but if visual cues are insufficient and the predator persists in the attack, a toxic secretion is eliminated in its mouth. This elimination is favoured by the absence of a calcified dermal layer in the macroglands, which makes the dermal region softer than the rest of the dorsal skin.
Hoverfly mimicry deceives humans
- Yvonne Golding, Roland Ennos, Matthew Sullivan, Malcolm Edmunds
-
- Published online by Cambridge University Press:
- 20 July 2005, pp. 395-399
-
- Article
- Export citation
-
It is believed that the resemblance of many hoverflies to stinging hymenopterans is a case of Batesian mimicry, though there is little experimental evidence that it is effective in protecting them from predators. In this study the effectiveness of hoverfly mimicry was investigated for humans by presenting groups of university students and schoolchildren with a questionnaire which included pictures of stinging hymenopterans, mimetic hoverflies and dipteran controls. More people thought that the mimics would sting than either of the control flies, though fewer than those who thought that the mimics' hymenopteran models would sting. This showed that the hoverflies' mimicry worked but was not 100% effective. More people thought that the good mimics would sting than poor mimics which were black and yellow, showing that the reaction was not just due to their warning coloration. Students' identification skills were poor; only 77%, 66% and 50% were able to correctly identify wasps, bumblebees and honeybees, respectively, but even knowledgeable students were confused by mimetic hoverflies. Significantly more of the students who had been stung thought that the Hymenoptera would sting and identified Hymenoptera correctly. Students who thought a hymenopteran would sting were in turn more likely to think that its mimic would sting. This suggests that the mimicry is partly mediated by experience. However, even students who had never been stung showed the same pattern of discrimination as those who had, suggesting that information is also passed on culturally. These results suggest that mimicry is effective and might help hoverflies avoid predation by birds but, as many of the subjects said they would kill a stinging insect, this would actually increase their chances of being killed by humans.
Molecular systematics and phylogeography in the fairy shrimp Tanymastix stagnalis based on mitochondrial DNA
- Valerio Ketmaier, Rita Mandatori, Elvira De Matthaeis, Graziella Mura
-
- Published online by Cambridge University Press:
- 20 July 2005, pp. 401-410
-
- Article
- Export citation
-
Patterns of sequence divergence in about 1 kb of mitochondrial DNA coding for two genes (16s rRNA and cytochrome oxidase I, COI) were analysed in 13 populations of the fairy shrimp Tanymastix stagnalis from Norway, Germany, France, Italy (northern and central Italy plus insular populations from Sardinia and the Tuscan Archipelago) and Spain, and in one presumed population of Tanymastix stellae from Corsica. The latter species was originally known only from a single locality in Sardinia, which has been destroyed by urbanization; the Corsican population was referred to T. stellae by some French authors on the basis of the collection of several cysts from mud. mtDNA data revealed a very low level of genetic divergence between the presumed population of T. stellae and the other T. stagnalis populations included in the study. Our genetic findings do not support the presence of T. stellae in Corsica and are in line with previous SEM studies revealing that all species belonging to the genus Tanymastix produce cysts with identical morphology. The results indicate complex phylogeographic relationships and pronounced genetic differentiation among T. stagnalis populations. The islands of Corsica and Sardinia on the one hand and the island of Capraia (Tuscan Archipelago) on the other were probably colonized independently at different times. Genetic relationships among continental populations do not follow a clear geographical trend, indicating that geographical distance is not the main force shaping the pattern of genetic structuring of the species. Stochastic factors such as multiple and independent founder events probably contributed to the striking pattern of genetic differentiation along with subsequent local adaptation. These results agree with previously published molecular work on several groups of aquatic organisms and further support the high potential for dispersal–low gene flow paradox shown by a large array of animals living in lentic habitats.
The short-term effect of sheep grazing on selected invertebrates (Diptera and Hemiptera) relative to other environmental factors in an alpine ecosystem
- Atle Mysterud, Lars Ove Hansen, Chris Peters, Gunnar Austrheim
-
- Published online by Cambridge University Press:
- 20 July 2005, pp. 411-418
-
- Article
- Export citation
-
Grazing by large herbivores is well-known to influence plant communities, while much fewer studies have been carried out on grazing effects on invertebrates. In Norway, some 2.2 million sheep graze on outlying pastures during summer, most of them in the alpine zone, but no study has reported the relative impact of sheep grazing on invertebrate communities relative to other environmental factors such as the plant community and altitude. A fully replicated landscape-scale experiment (2.7 km2) was performed with no, low (25 per km2) and high (80 per km2) sheep densities in an alpine habitat of Norway (1050–1300 m a.s.l.). The increased vulnerability hypothesis (H1) predicts that the more folivorous invertebrates, the higher the grazing pressure by sheep, as large herbivore grazing may stress the plants so they are more vulnerable to insect herbivory. The increased defence hypothesis (H2) predicts increased levels of general anti-herbivore defences, and thus a lower abundance of invertebrates with increasing sheep densities. Contrary to both predictions, no evidence was found that sheep grazing affected invertebrate richness, or abundance of folivorous, predatory or detritivore invertebrates – in a community dominated by Diptera and Hemiptera. Demonstrating an effect will always be a function of sample size, but at least our study shows that other environmental variables (such as plant species richness and functional plant richness) are more important determinants than sheep grazing for the selected invertebrate groups. Our study was short-term (first year of grazing) mainly designed to test specific hypotheses related to induced plant defences; long-term effects are probably owing to the impact sheep may have on vegetation composition, primary production, litter cover and soil properties.
Avian assimilation and dispersal of carbon and nitrogen brought ashore by breeding Westland petrels (Procellaria westlandica): a stable isotope study
- D. J. Hawke, R. N. Holdaway
-
- Published online by Cambridge University Press:
- 20 July 2005, pp. 419-426
-
- Article
- Export citation
-
Only a small proportion of the marine nutrients brought ashore by breeding colonial seabirds is retained in colony soils. However, means by which these marine nutrients can be dispersed to the wider terrestrial ecosystem have rarely been identified. In this study, moulted feathers from Hemiphaga novaeseelandiae (an endemic pigeon; n=9) and Gallirallus australis (an endemic flightless rail; n=3) and from a Procellaria westlandica (Westland petrel) colony were analysed for 13C and 15N enrichment. Potential diet items from both the colony and a control location were also analysed, and their contributions to the diets of H. novaeseelandiae and G. australis calculated. Hemiphaga novaeseelandiae assimilated marine N but not marine C, and showed a wide range in the significance of different diet sources. Food for most H. novaeseelandiae came from within the colony, implying minimal transport of marine nutrients to the wider terrestrial environment. All G. australis food came from within the colony, but 29–39% was from petrel tissue, or invertebrates feeding on petrel material. Thus, both H. novaeseelandiae and G. australis assimilated nutrients brought ashore by P. westlandica, but neither was shown to disperse the nutrients much beyond the petrel colony. However, birds that are now locally extinct may have dispersed marine nutrients more widely. Future research should focus on the consequences of restoring these species to petrel colonies as part of attempts to re-establish the functioning of pre-human ecosystems in New Zealand.
The Proceedings of the Zoological Society of London, 1859–1900: an exploration of breaks between calendar years of publication
- Edward C. Dickinson
-
- Published online by Cambridge University Press:
- 20 July 2005, pp. 427-430
-
- Article
- Export citation
-
Duncan (1937) provided detailed information that has been widely used to date names of new taxa described in early volumes of the Proceedings. The examinations reported here suggest that at least at the point where the year of publication is important Duncan was usually correct, and although exceptions are reported they are not of great consequence (although 14 of 42 volumes are anomalous). These exceptions relate to cases where the published pages differed from a multiple of the signature size by a couple of pages or so. Over the 41 volumes examined, two or more techniques were used to provide, economically, text needed to complete an article that would have over-run the number of signatures planned for the issue. The importance of retaining wrappers and binding them in is demonstrated by what can be learned from them.