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A new cytotype of Simulium squamosum Enderlein (Diptera: Simuliidae) (here named S. squamosum'D') is described from around Mount Cameroon in south-west Cameroon on the basis of sex-chromosome differences on the short arm of chromosome I. Two polymorphic inversions, IS-To (a new inversion) and IS-2, are partially Y linked. These inversions usually occur together, although IS-To has a higher frequency and is more strongly Y linked than IS-2. This sex-chromosome system has not been previously described and the occurrence and evolution of sex-chromosome systems in S. squamosum is discussed. 相似文献
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Zhang Fakui 《古脊椎动物学报》1994,(4)
Theatheriansandthetherianshavebothinheritedthesquamosa1fromthecyno-dontidancestry,theprimitivepropertyofthesquamosa1intheatherianlineagehavebeenmaintainedfromthebeginning(theLateTriassic,Morganucodontids)totheend(Cretaceous,Triconodontids).Inthetherianlineage,thelowertherianshavethesamesquamosalastheatherians,however,thehighertherianshaveapeculiarsquamosal,so,thechangeofthepropertyofthesquamosaImaytakeplacelntheevolutionaryphasefromthelowertherianmammals(Symmetrodonta,Eupan-totheria,Multitu… 相似文献
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M. Traore-Lamizana S. Somiari H. B. Mafuyai C. G. Vajime R. J. Post 《Medical and veterinary entomology》2001,15(2):219-223
On the basis of sex chromosome variation, three cytotypes of Simulium squamosum (Enderlein) (Diptera: Simuliidae) are described from Cameroon and Nigeria. Simulium squamosum A is the typical form as originally described by Vajime & Dunbar (1975) with chromosome I as the sex chromosome. It occurs throughout most of Cameroon and south-east Nigeria. A second cytotype, S. squamosum B, is described from the river Sanaga (Cameroon). It also has chromosome I as the sex chromosome, but the nature of the sex differential region is different. Simulium squamosum C has no sex-linked chromosomal rearrangements. It is widespread in Nigeria and occurs near Mount Cameroon, where it seems to hybridize with S. squamosum A. 相似文献
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S. E. O. MEREDITH D. A. BOAKYE J. N. RAYBOULD R. A. CHEKE † 《Medical and veterinary entomology》1987,1(2):193-199
Abstract. Males of the Beffa form of Simulium soubrense Vajime and Dunbar were successfully crossed with female S.squamosum V. & D. and S.sanctipauli V. & D. Fertile eggs from both crosses were reared to larvae and, in the case of the BeifaXsquamosum cross, to adults.
Larval chromosomes from the Beffa x sanctipauli cross had normally paired homologues but those of the Beffa xsquamosum cross showed extensive asynapsis and large heterozygous loops. The morphology of the larval and adult hybrids from the BeftaXsquamosum cross were more characteristic of squamosum , but the adult males had scutal patterns typical of the Beffa form and retained this form's laboratory-mating propensity. 相似文献
Larval chromosomes from the Beffa x sanctipauli cross had normally paired homologues but those of the Beffa xsquamosum cross showed extensive asynapsis and large heterozygous loops. The morphology of the larval and adult hybrids from the BeftaXsquamosum cross were more characteristic of squamosum , but the adult males had scutal patterns typical of the Beffa form and retained this form's laboratory-mating propensity. 相似文献
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Abstract. A vehicle-mounted net was used to make hourly catches of blackflies at 700–1000 m altitude in the River Assob valley, central Nigeria, on 20 days during the dry season. Pearson Correlation Matrix analysis of the collection data and meteorology showed that the main factors affecting flight activity of each of the four most abundant blackfly species were primarily light intensity and secondly wind velocity, whereas relative humidity was the least important factor. Right activity showed a negative linear regression against wind, with some activity occurring in wind speeds up to 15 km/h. Distance-weighted least-squares (DWLS) regressions showed little correlation of temperature with activity for Simulium hargreavesi and S.adersi , but S.squamosum and S.vorax had small peaks at 28C and 31C, respectively. DWLS regression against light intensity showed an activity peak at 6000 lux, except in Simulium adersi. 相似文献
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