Savanna Form Research Articles

Chimpanzees (Pan troglodytes verus) and their mammalian sympatriates: Mt. Assirik, Niokolo-Koba National Park, Senegal.

In intact, mosaic ecosystems, chimpanzees are sympatric with a wide range of other mammals, which may be predators, prey, or competitors. We delve beyond the nominal data of species lists to interval-level data on 35 medium-bodied and large-bodied mammals encountered at a hot, dry, and open field site in far West Africa. Frequency of encounter, habitat where found, and number of individuals encountered are analysed for species for which enough data were accumulated. Further, we compare findings over three periods (1976-1979, 2000, 2012). Species most often encountered were those normally classed as typical savanna forms. Even a crude classification into forest, woodland, and grassland ecotypes yields differences in species likely to meet apes. Comparison of encounter rates over time was surprisingly congruent, although not all species seen in the 1970s survived to the 2000s. Overall, Assirik's mammalian fauna is comparable to palaeo-faunal guilds sympatric with various extinct hominins.

Chromosome Inversions, Genomic Differentiation and Speciation in the African Malaria Mosquito Anopheles gambiae

The African malaria vector, Anopheles gambiae, is characterized by multiple polymorphic chromosomal inversions and has become widely studied as a system for exploring models of speciation. Near complete reproductive isolation between different inversion types, known as chromosomal forms, has led to the suggestion that A. gambiae is in early stages of speciation, with divergence evolving in the face of considerable gene flow. We compared the standard chromosomal arrangement (Savanna form) with genomes homozygous for j, b, c, and u inversions (Bamako form) in order to identify regions of genomic divergence with respect to inversion polymorphism. We found levels of divergence between the two sub-taxa within some of these inversions (2Rj and 2Rb), but at a level lower than expected and confined near the inversion breakpoints, consistent with a gene flux model. Unexpectedly, we found that the majority of diverged regions were located on the X chromosome, which contained half of all significantly diverged regions, with much of this divergence located within exons. This is surprising given that the Bamako and Savanna chromosomal forms are both within the S molecular form that is defined by a locus near centromere of X chromosome. Two X-linked genes (a heat shock protein and P450 encoding genes) involved in reproductive isolation between the M and S molecular forms of A. gambiae were also significantly diverged between the two chromosomal forms. These results suggest that genes mediating reproductive isolation are likely located on the X chromosome, as is thought to be the case for the M and S molecular forms. We conclude that genes located on the sex chromosome may be the major force driving speciation between these chromosomal forms of A. gambiae.

Indices of onchocerciasis transmission by different members of the Simulium damnosum complex conflict with the paradigm of forest and savanna parasite strains

Onchocerciasis in savanna zones is generally more severe than in the forest and pathologies also differ geographically, differences often ascribed to the existence of two or more strains and incompatibilities between vectors and strains. However, flies in the forest transmit more infective larvae than their savanna counterparts, even in sympatry, contradicting expectations based on the forest and savanna strains paradigm. We analysed data on the numbers of Onchocerca volvulus larvae of different stages found in 10 different taxonomic categories of the Simulium damnosum complex derived from more than 48,800 dissections of flies from Sierra Leone in the west of Africa to Uganda in the east. The samples were collected before widespread ivermectin distribution and thus provide a baseline for evaluating control measures. Savanna species contained fewer larvae per infected or per infective fly than the forest species, even when biting and parous rates were accounted for. The highest transmission indices were found in the forest-dwelling Pra form of Simulium sanctipauli (616 L3/1000 parous flies) and the lowest in the savanna-inhabiting species S. damnosum/S. sirbanum (135) and S. kilibanum (65). Frequency distributions of numbers of L1–2 and L3 larvae found in parous S. damnosum/S. sirbanum, S. kilibanum, S. squamosum, S. yahense, S. sanctipauli, S. leonense and S. soubrense all conformed to the negative binomial distribution, with the mainly savanna-dwelling species (S. damnosum/S. sirbanum) having less overdispersed distributions than the mainly forest-dwelling species. These infection patterns were maintained even when forest and savanna forms were sympatric and biting the same human population. Furthermore, for the first time, levels of blindness were positively correlated with infection intensities of the forest vector S. yahense, consistent with relations previously reported for savanna zones. Another novel result was that conversion rates of L1–2 larvae to L3s were equivalent for both forest and savanna vectors. We suggest that either a multiplicity of factors are contributing to the observed disease patterns or that many parasite strains exist within a continuum.

Functional traits of trees on and off termite mounds: understanding the origin of biotically‐driven heterogeneity in savannas

AbstractQuestionsIn African savannas, Macrotermes termites contribute to small‐scale heterogeneity by constructing large mounds. Operating as islands of high nutrient and water availability and low fire frequency, these mounds support distinct, diverse communities of trees that have been shown to be highly attractive to browsers. However, the distinct traits of tree species on termite mounds have hardly been studied, even though this may help to understand processes determining (1) their characteristic community structure and (2) attractiveness for browsers. Here, we compare functional trait and browser preference values between tree species on and off termite mounds.LocationHluhluwe‐iMfolozi Park, Kwazulu‐Natal, South Africa.MethodsWe recorded tree community compositions for 16 large Macrotermes natalensis mounds and 16 control plots of 100 m2 each in a paired design. For each observed tree species we measured 22 traits, related to water and nutrient use, fire tolerance, light competition and anti‐herbivore defence, and compared average trait values between mound and control communities. Furthermore, we investigated the feeding preferences of ungulate browsers for the most common tree species and how this was linked to their associated traits.ResultsTermite mounds supported tree communities that were distinct from the surrounding savanna vegetation. Mounds hosted more evergreen and less leguminous tree species than control communities, and the dominant species were less mechanically defended, less nutritious, had larger leaves and lower wood density than the species dominating control plots. Browsers preferred leguminous tree species with high leaf N and P content, which were relatively rare on termite mounds.ConclusionsOverall, we conclude that termite mounds in this savanna form small refuges for tree species that seem less adapted to fire (more evergreens), have low nutrient availability (less nitrogen fixers) and suffer from water stress (larger leaf sizes) than typical savanna trees. Surprisingly, despite their reputation as browsing hotspots, the tree species dominating mounds are less nutritious and less preferred by browsers than tree species of the surrounding savanna, which may be explained by the relatively nutrient‐rich nature of this savanna or intraspecific trait differences.

Differential Plasmodium falciparum infection of Anopheles gambiae s.s. molecular and chromosomal forms in Mali

BackgroundAnopheles gambiae sensu stricto (s.s.) is a primary vector of Plasmodium falciparum in sub-Saharan Africa. Although some physiological differences among molecular and chromosomal forms of this species have been demonstrated, the relative susceptibility to malaria parasite infection among them has not been unequivocally shown. The objective of this study was to investigate P. falciparum circumsporozoite protein infection (CSP) positivity among An. gambiae s.s. chromosomal and molecular forms.MethodsWild An. gambiae from two sites Kela (n = 464) and Sidarebougou (n = 266) in Mali were screened for the presence of P. falciparum CSP using an enzyme-linked immunosorbent assay (ELISA). Samples were then identified to molecular form using multiple PCR diagnostics (n = 713) and chromosomal form using chromosomal karyotyping (n = 419).ResultsOf 730 An. gambiae sensu lato (s.l.) mosquitoes, 89 (12.2%) were CSP ELISA positive. The percentage of positive mosquitoes varied by site: 52 (11.2%) in Kela and 37 (13.9%) in Sidarebougou. Eighty-seven of the positive mosquitoes were identified to molecular form and they consisted of nine Anopheles arabiensis (21.4%), 46 S (10.9%), 31 M (12.8%), and one MS hybrid (14.3%). Sixty of the positive mosquitoes were identified to chromosomal form and they consisted of five An. arabiensis (20.0%), 21 Savanna (15.1%), 21 Mopti (30.4%), 11 Bamako (9.2%), and two hybrids (20.0%).DiscussionIn this collection, the prevalence of P. falciparum infection in the M form was equivalent to infection in the S form (no molecular form differential infection). There was a significant differential infection by chromosomal form such that, P. falciparum infection was more prevalent in the Mopti chromosomal forms than in the Bamako or Savanna forms; the Mopti form was also the most underrepresented in the collection. Continued research on the differential P. falciparum infection of An. gambiae s.s. chromosomal and molecular forms may suggest that Plasmodium – An. gambiae interactions play a role in malaria transmission.

The ecology and biting activity of blackflies (Simuliidae) and the prevalence of onchocerciasis in an agricultural community in Ghana

Field studies on the ecology and biting activity of blackflies (Simuliidae), as well as an assessment of the prevalence status of Onchocerciasis diseases were conducted in a rural forest area of Ghana. It was observed that the blackfly vector Simulium damnosum s.l was the most abundant and widely distributed of the species encountered. The pH and flow rate of the breeding sites were significant factors influencing the distribution of the flies. The pattern of biting exhibited by S. damnosum s.l was bi-modal with morning and late afternoon peak activity. The savanna forms of the S. damnosum s.l were found to occur in the area representing 0.0–0.26% of the catch. The disease is endemic with the prevalence rate ranging between 0.0001 and 12.9% in the district and the frontline communities having infection rates exceeding 60%.

Spatial distribution of the chromosomal forms of anopheles gambiae in Mali

BackgroundMaps of the distribution of malaria vectors are useful tools for stratification of malaria risk and for selective vector control strategies. Although the distribution of members of the Anopheles gambiae complex is well documented in Africa, a continuous map of the spatial distribution of the chromosomal forms of An. gambiae s.s. is not yet available at country level to support control efforts.MethodsBayesian geostatistical methods were used to produce continuous maps of the spatial distribution of the chromosomal forms of An. gambiae s.s. (Mopti, Bamako, Savanna and their hybrids/recombinants) based on their relative frequencies in relation to climatic and environmental factors in Mali.ResultsThe maps clearly show that each chromosomal form favours a particular defined eco-climatic zone. The Mopti form prefers the dryer northern Savanna and Sahel and the flooded/irrigated areas of the inner delta of the Niger River. The Savanna form favours the Sudan savanna areas, particularly the South and South-Eastern parts of the country (Kayes and Sikasso regions). The Bamako form has a strong preference for specific environmental conditions and it is confined to the Sudan savanna areas around urban Bamako and the Western part of Sikasso region. The hybrids/recombinants favour the Western part of the country (Kayes region) bordering the Republic of Guinea Conakry.ConclusionThe maps provide valuable information for selective vector control in Mali (insecticide resistance management) and may serve as a decision support tool for the basis for future malaria control strategies including genetically manipulated mosquitoes.

Evidence for subdivision within the M molecular form of Anopheles gambiae.

The principal vector of malaria in sub-Saharan Africa, Anopheles gambiae is subdivided into two molecular forms M and S. Additionally, several chromosomal forms, characterized by the presence of various inversion polymorphisms, have been described. The molecular forms M and S each contain several chromosomal forms, including the Savanna, Mopti and Forest forms. The M and S molecular forms are now considered to be the reproductive units within A. gambiae and it has recently been argued that a low recombination rate in the centromeric region of the X chromosome has facilitated isolation between these forms. The status of the chromosomal forms remains unclear however. Therefore, we studied genetic differentiation between Savanna S, Forest S, Forest M and Mopti M populations using microsatellites. Genetic differentiation between Savanna S and Forest S populations is very low (F(ST) = 0.0053 +/- 0.0049), even across large distances. In comparison, the Mopti M and Forest M populations show a relatively high degree of genetic differentiation (F(ST) = 0.0406 +/- 0.0054) indicating that the M molecular form may not be a single entity, but could be subdivided into at least two distinct chromosomal forms. Previously it was proposed that inversions have played a role in the origin of species within the A. gambiae complex. We argue that a possible subdivision within the M molecular form could be understood through this process, with the acquisition of inversions leading to the expansion of the M molecular form into new habitat, dividing it into two distinct chromosomal forms.

The pyrethroid knock-down resistance gene in the Anopheles gambiae complex in Mali and further indication of incipient speciation within An. gambiae s.s.

In Mali the Anopheles gambiae complex consists of An. arabiensis and Mopti, Savanna and Bamako chromosomal forms of An. gambiae s.s. Previous chromosomal data suggests a complete reproductive isolation among these forms. Sequence analysis of rDNA regions led to the characterization of two molecular forms of An. gambiae, named M-form and S-form, which in Mali correspond to Mopti and to Savanna/Bamako, respectively, while it has failed so far to show any molecular difference between Savanna and Bamako. The population structure of An. gambiae s.l. was analysed in three villages in the Bamako and Sikasso areas of Mali and the frequency of pyrethroid resistance of the knock-down resistance (kdr) type was calculated. The results show that the kdr allele is associated only with the Savanna form populations and absent in sympatric and synchronous populations of Bamako, Mopti and An. arabiensis. This is the first molecular indication of barriers to gene flow between the Bamako and Savanna chromosomal forms. Moreover, analyses of specimens collected in the Bamako area in 1987 show that the kdr allele was already present in the Savanna population at that time, and that the frequency of this allele has gradually increased since then.

LACK OF TASK DIFFERENTIATION DURING PREY CAPTURE IN THE GROUP LIVING SPIDER STEGODYPHUS MIMOSARUM (ARANEAE, ERESIDAE)

Stegodyphus mimosarumof the African savanna form communal nests consisting of few to several hundred individuals and co-operate in nest construction and maintenance, brood care and prey capture. We tested large and small individuals for differential responses to different prey risk types. To date, there has been no conclusive evidence of tasking in these or other social spiders. If tasking occurs, small spiders should approach and attempt to subdue less dangerous prey items such as flies more often than the more dangerous prey items such as bees. Hungry individuals were significantly more willing to venture out of the nest refuge and thus accept the costs associated with prey capture than were satiated spiders. Apparent depletion of poison in previous prey captures did not significantly affect an individual's response to a prey item. Spiders treated more dangerous prey (bees) more carefully than less dangerous prey (flies), but there was no difference in the response of large versus small spiders to prey. The two- way interaction between spider size and prey type was never statistically significant, indicating a lack of tasking in this species.

Catalogue of the amphibians of Ethiopia, including a key for their identification

This review recognises 63 amphibian species in Ethiopia, a total that is sure to increase as many still remote regions come to be more adequately surveyed. It incorporates the following taxonomic changes: Bufo chappuisi Roux 1936 is considered a synonym of B. lughensis Loveridge 1932, Ptychadena largeni Perret 1994 a synonym of P. neumanni (Ahl 1924) and Rana schubotzi Sternfeld 1917 a synonym of Ptychadena tellinii (Peracca 1904). The ecological profile and zoogeographical affinities of every species is analysed and its recorded distribution within Ethiopia is mapped. More than half of these taxa are savanna forms, found in lowland areas around the margins of the central plateau and often widespread in other parts of Africa. In contrast, 25 species (40% of the total) are at present considered endemic; seven of the eight families include endemic representatives, amongst which are six endemic genera: Sylvacaecilia Wake 1987, Altiphrynoides Dubois 1987, Spinophrynoides Dubois 1987, Ericabatrachus Largen 1991, Balebreviceps Largen & Drewes 1989 and Paracassina Peracca 1907. Three species appear to be confined to lowland forest in southwestern Ethiopia, but the majority of endemics are most clearly associated with montane forest, grassland or moorland in the altitudinal range 1800–4000 m. Widespread environmental degradation by an ever-increasing human population is a severe problem in Ethiopia and the threat to montane and forest endemics, both known and yet to be discovered, gives particular cause for concern. National Parks, established to conserve selected environments for the benefit of entire communities, provide the best prospects for the protection of amphibian species in the immediate future. The Bale Mountains National Park alone provides a refuge for at least 17 amphibian taxa, including 48% of the endemic species and five of the six endemic genera.

Mapping distributions of chromosomal forms of Anopheles gambiae in West Africa using climate data

The mosquito Anopheles gambiae Giles sensu stricto (Diptera: Culicidae), the principal vector of malaria in West Africa, comprises several chromosomal forms (e.g. Bissau, Forest, Mopti, Savanna) associated with climatic zones. Here we show how climate data can be used to map the geographical distribution of these chromosomal forms. The climate at 144 sites surveyed for mosquitoes in West Africa between 1971 and 92 was determined using computerized climate surfaces. Forest and Bissau forms occurred at relatively wet sites: median annual precipitation 1325 mm and 1438 mm, respectively, interquartile ranges (IQR) 1144-1858 mm and 1052-1825 mm), whilst the Mopti form was found at dry sites (annual 938 mm, IQR 713-1047 mm) and the Savanna form at sites intermediate between the wet and dry forms (annual 1067 mm, IQR 916-1279). Logistic regression analyses of the climate variables were carried out on a stratified random sample of half the sites. The resulting models correctly classified over 80% of the sites for presence or absence of each chromosomal form. When these models were tested against excluded sites they were also correct at over 80% of sites. The combined data produced models that were correct at over 86% of sites. Mean annual precipitation, evapotranspiration, minimum temperature and maximum temperature were the most important climate variables correlated with the distribution of these forms of An. gambiae. We used the logistic models to map the distribution of each chromosomal form within the reported range for An. gambiae s.s. in West Africa employing a geographical information system. Our maps indicate that each chromosomal form favours particular climate envelopes in well-defined ecoclimatic zones, although these forms are sympatric at the edges of their ranges. This study demonstrates that climate can be used to map the distribution of chromosomal forms of insects across large areas.

Impact of irrigation on malaria in Africa: paddies paradox.

The high population growth rate of the African continent has led to an increased demand for food and is in danger of outstripping agricultural production. In order to meet this need, many governments have sought ways of improving food production by initiating large-scale irrigation projects, involving reclamation of arid and semi-arid areas for the cultivation of crops. Although crop irrigation promises one solution to alleviating hunger and encourages economic growth, irrigation has often been blamed for aggravating disease in local communities. Malaria is one of the major tropical diseases associated with irrigation schemes, and changes in the transmission pattern of this disease following irrigation development have been a perennial subject of debate. It has often been assumed that high numbers of malaria vector Anopheles mosquitoes (Diptera: Culicidae) resulting from irrigation schemes lead inevitably to increased malaria in local communities. However, recent studies in Africa have revealed a more complex picture. Increased numbers of vectors following irrigation can lead to increased malaria in areas of unstable transmission, where people have little or no immunity to malaria parasites, such as the African highlands and desert fringes. But for most of sub-Saharan Africa, where malaria is stable, the introduction of crop irrigation has little impact on malaria transmission. Indeed, there is growing evidence that for many sites there is less malaria in irrigated communities than surrounding areas. The explanation for this finding is still unresolved but, in some cases at least, can be attributed to displacement of the most endophilic and anthropophilic malaria vector Anopheles funestus Giles by An. arabiensis Patton with lower vectorial capacity, as the latter thrives more than the former in ricefields. Similarly, among members of the An. gambiae complex, some cytotypes of An. gambiae sensu stricto are more vectorial than others. For example, the Mopti form has high vectorial capacity and breeds perennially in irrigated sites, whereas the savanna form is often sympatric but more seasonal. Also we suggest that many communities near irrigation schemes benefit from the greater wealth created by these schemes. Consequently irrigation communities often have greater use of bednets, better access to improved healthcare and receive fewer infective bites compared with those outside such development schemes. Thus, in most cases, irrigation schemes in Africa do not appear to increase malaria risk, except in areas of unstable transmission. However, developers should take the opportunity to improve health-care facilities for local communities when planning irrigation schemes wherever they occur.

Molecular characterization of ribosomal DNA polymorphisms discriminating among chromosomal forms of Anopheles gambiae s.s.

The sequence of a 2.3 kb long DNA segment derived from the 5'-most end of the ribosomal intergenic spacer was determined in three chromosomal forms of Anopheles gambiae s.s. The analysis revealed that the sequence of the Mopti form differed from that of the Bamako and Savanna forms by a total of ten nucleotide substitutions. Using these sequence variations we set up a diagnostic polymerase chain reaction (PCR) assay to distinguish mosquitoes belonging to the three chromosomal forms, facilitating studies on the distribution and the ecology of these incipient taxa. The assay also allows to distinguish whether a given specimen could represent a heterozygote between Mopti and Savanna or Bamako.

Molecular evidence of incipient speciation within Anopheles gambiae s.s. in West Africa.

We karyotyped and identified by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis Anopheles gambiae s.s. samples collected in several African countries. The data show the existence of two non-panmictic molecular forms, named S and M, whose distribution extended from forest to savannahs. Mosquitoes of the S and M forms are homosequential standard for chromosome-2 inversions in forest areas. In dry savannahs, S is characterized mainly by inversion polymorphisms typical of Savanna and Bamako chromosomal forms, while M shows chromosome-2 arrangements typical of Mopti and/or Savanna and/or Bissau, depending on its geographical origin. Chromosome-2 inversions therefore seem to be involved in ecotypic adaptation rather than in mate-recognition systems. Strong support for the reproductive isolation of S and M in Ivory Coast comes from the observation that the kdr allele is found at high frequencies in S specimens and not at all in chromosomal identical M specimens. However, the kdr allele does not segregate with molecular forms in Benin.

Another new species ofPtychadenaBoulenger 1917 from Ethiopia (Amphibia Anura Ranidae)

Ptychadena wadei n. sp. is described from grassland at moderate elevation, south of Lake Tana in Ethiopia. The new taxon is distinguished from all NE African congeners with comparably restricted webbing by its small size, compact body form, the arrangement of skin folds on the back and details of colour pattern, particularly on the hindlimbs. It remains unknown whether P. wadei is a montane endemic, with a type locality perhaps near the lower limit of its altitudinal range, or a more widespread savanna form that has succeeded in penetrating the foothills of the Ethiopian plateau. Lake Tana and the surrounding mountains are a part of the country much in need of further herpetological study.

Análise da estrutura de duas unidades fitofisionômicas de savana (cerrado) no sul do Brasil

A região de Jaguariaíva. situada no Estado do Paraná, sul do Brasil, abriga os últimos remanescentes de savana no Estado e pode ser considerada como marco do limite meridional de distribuição deste tipo de vegetação no Brasil. O Parque Estadual do Cerrado (24º09" S; 50º18' WG) foi objeto deste estudo em que se analisou a estrutura da vegetação de duas fornias fisionômicas de savana, o campo cerrado e o cerrado sensu stricto. Estas duas formas são predominantes na área do Parque, ainda que este não seja coberto exclusivamente por vegetação savânica. Vinte parcelas com dimensões de 200m² (20 X 10m) foram alocadas sistematicamente em cada unidade fisionômica, onde todo indivíduo com perímetro basal (PB) igual ou maior a 15cm foi amostrado. Os resultados do levantamento apontaram para pequeno número de espécies lenhosas em ambos os tipos fisionômicos (33 espécies no cerrado sensu stricto e 18 no campo cerrado). As espécies mais importantes foram virtualmente as mesmas em ambas as formas fisionômicas, destacando-se Byrsonima coccolobifolia. Acosníium subelegans. Couepia grandiflora e Stryphnodendron adstringens. A densidade total, dominância total e diversidade foram mais elevadas no cerrado sensu stricto. Além disso, ficou aparente a maior semelhança florística com as savanas de São Paulo, especialmente aquelas situadas ao sul deste Estado.

An annotated checklist of the amphibians and reptiles of Eritrea, with keys for their identification

Most herpetological research in Eritrea was conducted during the period 1827–1930 and was almost exclusively the preserve of Italian enthusiasts, who concentrated their efforts within an 80 km radius of Asmara. Virtually no field work has been undertaken on the Eritrean mainland in the past 65 years and a great deal still remains to be learned about the composition, distribution and status of the herpetofauna. The 109 species provisionally listed in the present work (Anura 19, Testudines 9, Crocodylia 1, Sauria 45, Serpentes 35) are predominantly savanna (37.5%) and deserticolous (33.1%) forms and the Eritrean highlands are impoverished by aridity. Of eight taxa which extend into this region from the Ethiopian Plateau, only three appear to be genuinely montane and the ability of the remainder to colonise lowland sites elsewhere in their ranges is taken as evidence of their resistance to drought conditions. Rhinotyphlops erythraeus (Scortecci 1928), which is known only from the type locality at an altitude...

Catalogue of the mammals of Ethiopia and Eritrea. 7. Revised checklist, zoogeography and conservation

This review of the Ethiopian and Eritrean mammal fauna recognises provisional totals of 277 terrestrial and 11 marine species. The terrestrial fauna is dominated by savanna forms (47.2% of the total), most of which are widespread but with significant numbers being derived from either the East African savannas or the sub-Saharan savanna belt. Deserticolous species (16.2%) include many which are clearly associated with the Somali-arid zone. The 29 endemics are almost exclusively confined to the central plateaux at altitudes in excess of 1800 m and most are denizens of grassland or moorland habitats; few are forest species. Sylvicolous mammals are equally poorly represented amongst non-endemic forms (6.5%) and it is concluded that Ethiopian forests have an impoverished fauna compared with those of Uganda and Zaire. Conservation of wildlife, perennially starved of resources, has suffered greatly from neglect, poaching and destruction of property during the political crises of recent years. This situation is n...

Species composition and inversion polymorphism of the Anopheles gambiae complex in some sites of Ghana, West Africa

Samples of Anopheles gambiae s.1. were collected from eight localities belonging to four of the five main ecological strata of Ghana. Analysis of ovarian polytene chromosomes revealed the presence of A. gambiae s.s. in all the sites studied, while A. arabiensis was detected only in the extreme northern locality of Navrongo and A. melas in some southern sites. Anopheles arabiensis showed a degree of inversion polymorphism comparable to the one observed in other West African countries. The analysis of the chromosomal polymorphism of A. gambiae s.s. showed the presence of the FOREST form in the rain forest localities and the SAVANNA form in the coastal savanna sites. The MOPTI form occurred sympatrically with the SAVANNA form in the northernmost locality. The possible influence of the presence of various taxa of the A. gambiae complex and of their intra-specific variants on malaria vectorial system is discussed.