Habitat preference of the Preuss's guenon<Emphasis Type="Italic">(Cercopithecus preussi), on Bioko island,Equatorial Guinea</Emphasis>

The Press's guenon (Cercopithecus preussi) is considered to be one of the most threatened African primates. There is little information on the ecology and status of this primate on Bioko island, where it is found in the form of an endemic subspecies. The Press's, guenon shows preference for theSchefflera forest and the mountain habitat on Bioko island. As on the mainland they also have semitterrestrial habits and are found usually at the understorey of the forest. Competitive exclusion between this guenon and other guenon species could be an explanation of these ecological preferences. Habitat use and vertical stratification of the activity in the forest canopy seem to reduce competition with other sympatric primate species that inhabit on the island. Habitat destruction, and isolation in a reduced habitat, show to be the major threats for the survival of this primate on Bioko island.     

A simple non-parametric GIS model for predicting species distribution: endemic birds in Bioko Island, West Africa

Species mapping is a useful conservation tool for predicting patterns of biological diversity, or identifying geographical areas of conservation significance. Mapping can also improve our understanding of the appropriateness of habitat areas for individual species. We outline a computer-based methodology, PREDICT, for the analysis of the habitat requirements of species in a combined GIS-statistical programming environment. The paper details the statistical background to the approach adopted, the program structure and input file information and then applies these techniques to bird data from Bioko Island, West Africa. It produces images and statistics that assess the potential of unstudied areas for wildlife for which presence/absence data and basic habitat information are available. Suitability for target species is determined within surveyed and non-surveyed squares by a form of weights of evidence. The program measures the degree of association between habitat factors and presence/absence of target species by means of ² tests. The overall suitability weighting of each square, as the sum of all individual habitat factor weightings, is finally displayed in maps depicting areas of highly suitable, suitable, unsuitable and highly unsuitable habitat. Statistical relations between vegetation, rainfall and landscape features on Bioko Island and the location of 9 endemic bird taxa are presented herein. Final confirmation of the accuracy of predictions of the studied bird taxa will ensue from future field observations. However, in a series of misclassification tests of the program, actual distribution detection rate was in excess of 90%. The use of PREDICT can guide investigations of little known species in remote areas and provide a practical solution to identify areas of high rare species diversity in need of conservation.     

Distribution and conservation status of primates in Bioko island,Equatorial Guinea

Ten species of non-human primates are indigenous to Bioko; half of these are endangered and between five and eight are endemic subspecies. Recent data on their status and distribution have been lacking. In 1986, a ten-week survey of the island was carried out to determine the distribution and status of the primates and the natural vegetation, and to evaluate the effects of man on them. This paper presents the results of that survey, gives an update of conservation achievements since 1986, and highlights current concerns. Between 1974 and 1986 it is probable that numbers of all Bioko primates rose as a result of an increase in habitat and of reduced hunting. At the time of the survey there was considerably more natural, undisturbed, vegetation remaining in Bioko tran expected. Much of this vegetation occurs within two large blocks that are of outstanding importance to the conservation of species in tropical Africa, particularly of plants and primates.     

The blackflies (Diptera: Simuliidae) of Bioko (Republic of Equatorial Guinea) and the Gulf of Guinea with a description of the larvae of the 'Pomeroy' form of Simulium cervicornutum

Abstract.  Like many other organisms, Simuliidae often show a high degree of endemism on oceanic islands, and the Gulf of Guinea, including its islands, is a region of general biogeographical interest in view of the uniqueness of its flora and fauna. This paper presents a comprehensive review of the Simuliidae in the region, and is the first faunistic record of blackflies from Bioko. Simuliidae (larvae, pupae and neonate adults) were collected from Bioko and from around Mount Cameroon and compared with previous findings from Mount Cameroon, Príncipe and São Tomé. Twenty-seven species are known from the region. Twenty-five species have been recorded around Mount Cameroon, eight species on Bioko, three species on São Tomé and one species on Príncipe. Two taxonomic 'forms' (one on Bioko alone, and one on both Bioko and around Mount Cameroon) and one species (found only on São Tomé) are endemic to the region. A study of the variation in the morphology of Simulium cervicornutum revealed two morphotypes, one from Bioko and around Mount Cameroon and the other from the rest of Africa. The speciation and biogeography of the Simuliidae in the Gulf of Guinea are discussed.     

Temperate migrants and resident bird species in Afro‐tropical savannahs show similar levels of ecological generalism

The specificity of an animal's habitat requirements will determine its ability to deal with anthropogenic climate and habitat change. Migratory birds are thought to be particularly vulnerable to such change, but theory predicts that they should be largely generalists. This prediction was tested with the aim of assessing whether migratory Palaearctic‐breeding birds wintering in the savannah biome of Africa are more or less generalist in their habitat use compared with taxonomically and ecologically similar Afro‐tropical resident species. The degree of specialization of these species groups to certain habitat characteristics was assessed and compared by calculating the relative occurrence of the species along habitat gradients, where wide occurrence indicates generalism and narrow occurrence indicates specialism. Palaearctic migrants as a group could not clearly be distinguished as generalists relative to Afro‐tropical residents with respect to habitat attributes. The only indication of greater flexibility in Palaearctic migrants was a significant tendency to use habitats over a wider latitudinal range. The results suggest that migrants are generalists, but not necessarily more generalist than taxonomically similar resident species that also occur over a wide range of habitat types within the savannah biome. The availability of specific habitat requirements on the wintering grounds in Africa is therefore unlikely to be a primary limiting factor for many Afro‐Palaearctic migratory bird species.     

Three acoustic forms of Allen's galagos (Primates; Galagonidae) in the Central African region

This study identifies populations currently classified as Allen's galago (Galago alleni) at ten locations in Gabon, Cameroon and Bioko Island. Morphological diversity was evident both within and between populations. Attention to the loud calls revealed three distinct vocal profiles which are consistent within biogeographical regions. This work is based on the Recognition Concept of Species which refers to a Specific Mate Recognition System. Galagos rely less on visual signals than diurnal primates and recognise each other principally by means of auditory and olfactory signals. Galagos possess repertoires of loud calls relating to contact and alarm which are thought to be species-specific. Other studies of nocturnal prosimians (galagos, tarsiers) have demonstrated that the unique loud call repertoires are reliable indicators of species boundaries; whereas characters such as body size and pelage coloration are highly variable, even within populations. The vocal data in this study provide evidence of at least three acoustic forms of galago within the Allen's group which are predicted to represent three distinct species: the Allen's form on Bioko Island and south-west Cameroon, the Gabon form in southern Cameroon and northern Gabon and the Makandé form in Gabon south of the Ogooué river. Some populations may be vulnerable to extinction due to limited distributions and habitat destruction. Electronic Publication     

Biogeographical considerations of fish diversity in Bioko

The present study on the fish fauna of Bioko reports a total of 43 species of 21 families; 18 of which are new records for the island. Bioko's icthyofauna is made up of 17 freshwater and 26 saltwater and brackish water species. Freshwater fishes are primarily restricted to a narrow belt along the north and west of the island, similar to the adjacent volcanic region around Mount Cameroon. The rest of the island, however, is inhabited by salt tolerant fishes, as found in São Tomé, Príncipe and Annobón. Fish communities also vary according to elevation since rivers on Bioko are characterized by steep gradients from source to sea. Pressures on Bioko's river systems are not alarmingly high but may increase in the future because of the use of toxic products (lime and insecticides) for fishing. There is no doubt that this is having a significant effect on northern and western rivers which are precisely the most species-rich. Aphyosemion oeseri, which is endemic to Bioko, and which has a distribution restricted to the small northern rivers is in great danger of extinction. P. monkei is in a similarly precarious situation, given that it is extremely rare and will probably disappear altogether in a few years from the island's rivers. Before the situation becomes irreversible urgent measures must be taken to improve matters through educational campaigns as well as through cleaning up heavily-polluted rivers and re-stocking them with fish species from neighbouring river basins.     

DO CONSTANT ENVIRONMENTS PROMOTE COMPLEXITY OF FORM?: THE DISTRIBUTION OF BRYOZOAN POLYMORPHISM AS A TEST OF HYPOTHESES

The distribution of cheilostome bryozoans on the Caribbean reefs of Panama was surveyed to test the hypothesis that physically constant environments favor increased morphologic complexity, expressed as the number of zooid types within a colony. The proportion of species within defined grades of complexity did not vary significantly with locality, depth, or substratum. Some differences were found in grade-specific ecological success, measured by colony abundance and spatial cover, but these were not consistently related to habitat type. There was no inverse correlation between morphologic complexity and range of distribution: morphologically specialized cheilostomes were not more stenotopic than generalized forms. Patterns of distribution and total space occupation indicate a sensitivity to local habitat conditions, but relative success of species was not correlated with level of polymorphism. In a bryozoan fauna from Florida, the frequency of polymorphic species was weakly associated with constancy of habitat. In estuaries, polymorphic cheilostomes are almost absent at salinities below 18‰, but this pattern is strongly confounded taxonomically. All species tolerant of low salinities are encrusting anascans; within this group, polymorphism does not decrease significantly with declining salinity. Bryozoan faunas from different biogeographic zones may vary in frequency of avicularian polymorphism, but not along a simple latitudinal cline. These large-scale comparisons may be strongly biased historically and taxonomically. The distribution of cheilostome polymorphism on a local and geographic scale provides no evidence for a causal relationship between habitat constancy and morphologic specialization at the zooidal level. This is in striking contrast to the strong habitat dependence of colony form, which suggests that selective processes may operate differently at the zooidal and colonial levels.     

Biodiversity in the Gulf of Guinea: an overview

Patterns of species-richness and endemism in the Gulf of Guinea reflect the region's biogeographic history. Bioko is a continental-shelf island that was recently connected to the African mainland, whereas Príncipe, São Tomé and Annobón are truly oceanic and have never been connected with each other or with the mainland. As a result, Bioko supports a much more diverse flora and fauna but with relatively low levels of endemism at the species level, whereas the oceanic islands are relatively depauperate because of their isolation but rich in endemic taxa. Species endemism is 0–3% on Bioko for angiosperms, bats, birds, reptiles and amphibians, compared with much higher values on Principe for these same taxa of 8% (plants) to 100% (amphibians), on São Tomé between 14% (plants) and 100% (amphibians), and on Annobón 0% (bats) to 71% (reptiles). On a global scale, for their size both Príncipe and São Tomé support unusually high numbers of single-island endemic species of birds, reptiles and amphibia. For its tiny size, Annobón is also notable for its endemic birds and reptiles. Among terrestrial molluscs the rates of endemism are in general higher than for plants and vertebrates, from ca 50% on Bioko to ca 80% on the oceanic islands. In contrast and as might be expected, only Bioko supports a rich freshwater fish fauna and it contains many endemic taxa, whereas the oceanic islands support only a few salt-tolerant species. The Gulf of Guinea islands are also important for their marine organisms, amongst which coral reef fish and marginellid molluscs show high levels of endemism, though they are not especially species-rich. The Gulf of Guinea islands are of great interest to conservationists and evolutionary biologists. Each island, of greatly differing size and degree of isolation, has acquired its unique sub-set of plants and animals separately from the neighbouring mainland, followed by adaptive radiations in situ. For this reason the conservation value of the archipelago as a whole is greater than the sum of the biodiversity contained in its individual islands. Conservation initiatives in the Gulf of Guinea should therefore ensure that representative terrestrial, freshwater and marine habitats and groups of organisms are targeted in a co-ordinated manner among the islands.     

Genetic isolation within the malaria mosquito Anopheles melas

Anopheles melas is a brackish water–breeding member of the Anopheles gambiae complex that is distributed along the coast of West Africa and is a major malaria vector within its range. Because little is known about the population structure of this species, we analysed 15 microsatellite markers and 1161 bp of mtDNA in 11 A. melas populations collected throughout its range. Compared with its sibling species A. gambiae, A. melas populations have a high level of genetic differentiation between them, representing its patchy distribution due to its fragmented larval habitat that is associated with mangroves and salt marsh grass. Populations clustered into three distinct groups representing Western Africa, Southern Africa and Bioko Island populations that appear to be mostly isolated. Fixed differences in the mtDNA are present between all three clusters, and a Bayesian clustering analysis of the microsatellite data found no evidence for migration from mainland to Bioko Island populations, and little migration was evident between the Southern to the Western cluster. Surprisingly, mtDNA divergence between the three A. melas clusters is on par with levels of divergence between other species of the A. gambiae complex, and no support for monophyly was observed in a maximum‐likelihood phylogenetic analysis. Finally, an approximate Bayesian analysis of microsatellite data indicates that Bioko Island A. melas populations were connected to the mainland populations in the past, but became isolated, presumably when sea levels rose after the last glaciation period (≥10 000–11 000 bp ). This study has exposed species‐level genetic divergence within A. melas and also has implications for control of this malaria vector.     

The Holes of Moles: Osteological Correlates of the Trigeminal Nerve in Talpidae

Talpidae consists of small insectivorous mammals exhibiting a range of environmental preferences. As all its members rely on a highly developed somatosensation system, they are an ideal study-group for investigating osteological correlates of the trigeminal nerve. We quantitatively studied cranial anatomy in 22 species of desman, shrew-mole, and true mole using microscopy and micro-CT imaging to investigate whether the infraorbital foramina within Talpidae is enlarged in semiaquatic forms and more broadly associated with habitat preference. We also investigated whether associated foramina were covariant. In order to account for a phylogenetic basis for any correlations, we reconstructed the best taxonomically sampled phylogeny for talpids in the literature to date, based on cytochrome b. Relationships among genera and species are broadly congruent with previous analyses; however, we report new placements for Neurotrichus gibbsii and Mogera tokudae. Although no correlation was found between habitat and the caliber of the V₃ associated mandibular canal and foramen ovale, our results indicate that semiaquatic forms show larger infraorbital foramina in comparison to terrestrial species, and that the caliber of the sphenorbital fissure can also serve as a proxy for habitat preference. This work, therefore, supports the use of certain osteological features to infer habitat preferences in fossil species and indicates this can be achieved even when studying ecologically diverse, closely related species within the same family.     

Correlation between phylogenetic structure and function: examples from deep-sea Shewanella

The genus Shewanella is one of the typical deep-sea bacterial genera. Two isolated deep-sea Shewanella species, Shewanella benthica and Shewanella violacea, were found to be able to grow better under high hydrostatic pressure conditions than at atmospheric pressure. These species are not only piezophilic (barophilic), but also psychrophilic. Many psychrophilic and psychrotolerant Shewanella species have been isolated and characterized from cold environments, such as seawater in Antarctica or the North Sea. Some of these cold-adapted Shewanella were shown to be piezotolerant, meaning that growth occurs in a high-pressure habitat. In this review, we propose that two major sub-genus branches of the genus Shewanella should be recognized taxonomically, one group characterized as high-pressure cold-adapted species that produce substantial amounts of eicosapentaenoic acid, and the other group characterized as mesophilic pressure-sensitive species.     

Host range testing of a prospective classical biological control agent against cabbage maggot,Delia radicum,in Canada

The introduction of a European natural enemy, Aleochara bipustulata L. (Coleoptera: Staphylinidae), is being considered for control of cabbage maggot, Delia radicum (L.) (Diptera: Anthomyiidae) in canola in Canada, and the host specificity of this pupal parasitoid must first be studied. Contemporary guidelines were used to select 18 species of Diptera to represent non-target species taxonomically related or ecologically similar to reported hosts of A. bipustulata, or beneficial species. No-choice tests were used to determine which of the 18 species are within A. bipustulata’s fundamental host range, and whether puparial structure or mass or duration of pupal development influence their acceptability and suitability as hosts. Five species were consistently suitable as hosts, and these were either relatively small or were taxonomically closely related to the target host. The probability that a puparium would be entered by a parasitoid larva was greatest for small puparia, but was unaffected by pupal duration. The probability of completing parasitoid development once a puparium was entered was influenced by both puparial mass and duration of pupal development. Pitfall traps to assess habitat associations caught A. bipustulata adults in a variety of crop habitats but none were caught in forests. Host range and habitat data are used to argue that there is little risk of parasitism to beneficial taxa. Non-target species taxonomically closely related to the target D. radicum or with small puparia may fall within the fundamental host range of A. bipustulata. However, risk to many of these species may be minimal because of the habitat preferences of the parasitoid and its cues for host-finding and recognition.     

Distribution of the Simulium damnosum complex on Bioko island, Equatorial Guinea, and the potential for onchocerciasis elimination by vector eradication

Onchocerciasis is endemic on the island of Bioko, Equatorial Guinea, where it is transmitted by the 'Bioko form' of the Simulium damnosum complex, a cytospecies unique to the island. To determine the distribution of vector breeding, three dry season and two wet season expeditions were made in 1989, 1996 and 1997, and 226 of the island's 247 rivers (91.5%) were visited. Of these 226 rivers, 130 (58%) were flowing during the dry season, forty-five (20%) supported aquatic stages of Simuliidae of any species and twenty-five (11%) contained larvae or pupae of the S. damnosum complex. The twenty-one rivers not prospected were in the mountainous south of the island, where an additional seventeen rivers were reached but not satisfactorily prospected. Of these thirty-eight rivers, twenty-nine were considered highly likely to support vector breeding, bringing the total number of rivers which could harbour the vector during the dry season to fifty-four (21.9% of the island's total). Breeding was believed to be limited to river stretches below 1000 m altitude, and during the dry season the total length of those stretches which could support breeding on Bioko was estimated to be 1020 km. A combination of factors, including low river discharges during the dry season, the relatively low water temperature on Bioko, the suitability of limited stretches of most rivers as vector breeding sites and the close proximity of many rivers within a small geographical area, render the vector vulnerable to eradication by aerial treatment of rivers with insecticide. The isolation of the Bioko form of the S. damnosum complex suggests that reinvasion following treatment would be unlikely, and eradication of the vector might be achieved by a dry season larviciding programme in one or two years.     

Exploring morphological evolution in relation to habitat moisture in the moss genus Fissidens using molecular data generated from herbarium specimens

Morphological evolution in mosses has long been hypothesized to accompany shifts in microhabitats, which can be tested using comparative phylogenetics. These lines of inquiry have been developed to include target capture sequencing, which can yield phylogenomic scale data from herbarium specimens. Here, we test the relationship between taxonomically important morphological characters in the moss genus Fissidens, using a 400-locus data set generated using a target-capture approach in tandem with a three-locus phylogeny generated using Sanger sequencing. Phylogenetic trees generated using ASTRAL and Bayesian inference were used to test the monophyly of subgenera/sections. These trees provide the basis for ancestral character state reconstructions and phylogenetic correlation analyses for five morphological characters and characters related to the moisture habitat, scored from the literature and by specimen inspection. Many of these characters exhibit statistically significant phylogenetic signal. Significant correlations were found between the limbidium (phyllid/leaf border of the gametophyte) and habitat moisture niche breadth, which could be interpreted as the more extensive limbidium enabling species to survive across a wider variety of habitats. We also found correlations between costa anatomy, peristome morphology, and the limbidium, which could reflect the evolutionary recruitment of genetic networks from the gametophyte to the sporophyte phase. The correlation found between average habitat moisture and the sexual system indicates that dioicous and polyoicous species are more likely to be found in moist habitats and that these higher moisture levels could be particularly, reproductively advantageous to species with separate sexes.     

Abundance–occupancy relationships in deep sea wood fall communities

The generally positive relationship between the number of sites a species occupies and its average abundance within those sites provides an important link between population processes occurring at different spatial scales. Although such abundance–occupancy relationships (AORs) have been documented across a very wide range of taxa and in many different environments, little is known of such patterns in Earth's largest ecosystem, the deep sea. Wood falls – derived from natural or anthropogenic inputs of wood into the oceans – constitute an important deep‐sea habitat, habouring their own unique communities ultimately entirely dependent on the wood for chemical energy. In this study we take advantage of the unique features of an experimental wood fall deployment to examine AORs for the first time in deep‐sea invertebrates. The study design combines advantages of both experimental (tractability, control of key environmental parameters) and observational (natural colonisation by taxonomically diverse communities) studies. We show that the interspecific AOR is strongly positive across the 48 species occurring over 32 wood fall communities. The precise form of the AOR is mediated by both species‐level life history (body size) and by the colonisation stage at which communities were harvested, but not by environmental energy (wood fall size). Temporal dynamics within species are also generally consistent with positive intraspecific AORs. This support for positive AORs in the deep sea is an important extension of a macroecological generality into a new environment offering considerable potential for further testing and developing mechanistic macroecological theories.     

Habitat associations of juvenile fish at Ningaloo Reef, Western Australia: the importance of coral and algae

Habitat specificity plays a pivotal role in forming community patterns in coral reef fishes, yet considerable uncertainty remains as to the extent of this selectivity, particularly among newly settled recruits. Here we quantified habitat specificity of juvenile coral reef fish at three ecological levels; algal meadows vs. coral reefs, live vs. dead coral and among different coral morphologies. In total, 6979 individuals from 11 families and 56 species were censused along Ningaloo Reef, Western Australia. Juvenile fishes exhibited divergence in habitat use and specialization among species and at all study scales. Despite the close proximity of coral reef and algal meadows (10's of metres) 25 species were unique to coral reef habitats, and seven to algal meadows. Of the seven unique to algal meadows, several species are known to occupy coral reef habitat as adults, suggesting possible ontogenetic shifts in habitat use. Selectivity between live and dead coral was found to be species-specific. In particular, juvenile scarids were found predominantly on the skeletons of dead coral whereas many damsel and butterfly fishes were closely associated with live coral habitat. Among the coral dependent species, coral morphology played a key role in juvenile distribution. Corymbose corals supported a disproportionate number of coral species and individuals relative to their availability, whereas less complex shapes (i.e. massive & encrusting) were rarely used by juvenile fish. Habitat specialisation by juvenile species of ecological and fisheries importance, for a variety of habitat types, argues strongly for the careful conservation and management of multiple habitat types within marine parks, and indicates that the current emphasis on planning conservation using representative habitat areas is warranted. Furthermore, the close association of many juvenile fish with corals susceptible to climate change related disturbances suggests that identifying and protecting reefs resilient to this should be a conservation priority.     

Shared and unique features of diversification in Greater Antillean Anolis ecomorphs

Examples of convergent evolution suggest that natural selection can often produce predictable evolutionary outcomes. However, unique histories among species can lead to divergent evolution regardless of their shared selective pressures-and some contend that such historical contingencies produce the dominant features of evolution. A classic example of convergent evolution is the set of Anolis lizard ecomorphs of the Greater Antilles. On each of four islands, anole species partition the structural habitat into at least four categories, exhibiting similar morphologies within each category. We assessed the relative importance of shared selection due to habitat similarity, unique island histories, and unique effects of similar habitats on different islands in the generation of morphological variation in anole ecomorphs. We found that shared features of diversification across habitats were of greatest importance, but island effects on morphology (reflecting either island effects per se or phylogenetic relationships) and unique aspects of habitat diversification on different islands were also important. There were three distinct cases of island-specific habitat diversification, and only one was confounded by phylogenetic relatedness. The other two unique aspects were not related to shared ancestry but might reflect as-yet-unmeasured environmental differences between islands in habitat characteristics. Quantifying the relative importance of shared and unique responses to similar selective regimes provides a more complete understanding of phenotypic diversification, even in this much-studied system.