Leaf Spots Induced by Ascochyta pisi and Mycosphaerella pinodes

The leaf-spot pathogens, Ascochyta pisi and Mycosphaerella pinodes,both cause limited, necrotic lesions in detached pea leafletssuspended above water. When leaflets were floated on water A.pisi lesions were still limited, but those caused by M. pinodesspread rapidly to occupy all the leaflet tissue. Increasing the numbers of spores in inocula decreased numbersof mature lesions caused by A. pisi, but increased numbers ofspreading lesions caused by M. pinodes. Older leaflets weremore susceptible to both pathogens. Studies of penetration and colonization of leaves with the aidof light and electron microscopy showed that cell-wall-degradingenzymes were involved in the formation of A. pisi lesions andin spreading lesions caused by M. pinodes. There was littleevidence of cell-wall degradation in limited M. pinodes lesionsin which penetration of walls by hyphae seemed to be mechanicalin nature. No physical barriers developed in tissues surrounding limitedlesions. Nevertheless, A. pisi was rarely found beyond the necroticarea. This suggested that tissues beyond the lesion had becomeresistant to the parasite. In contrast, M. pinodes often grewoutside the necrotic area, sometimes many days after this hadstopped growing, but when it did so it caused no more necrosisunless leaflets were placed in conditions in which the spreadingtype of lesion could develop.     

Changes in sperm tail development associated with Y chromosome meiotic drive leading to an excess of males in the medfly Ceratitis capitata (Diptera: Tephritidae)

The Mediterranean fruit fly Ceratitis capitata (Wied.) normally produces the sexes in equal ratio but strains carrying the Y chromosome meiotic drive MP (male‐producing) factor show an excess of males. This is associated with a loss of sperm, and abnormal sperm structure in terms of multiple axonemes, atypical numbers of mitochondrial derivatives, and sometimes an incorrect initial orientation of paracrystalline bodies to the axoneme. Sperms are bundled together within spermatocysts, and those with depleted content and abnormalities occur in the same MP testes as normal spermatocysts. The maximum number of sperms per cyst in control strains was 256, each with a single axoneme originating from a single centriole (kinetosome). The maximum per cyst in MP strains was also 256 but MP cysts contained up to 300 axonemes, providing evidence of multiplication of centrioles. The structural changes in MP sperm are discussed in relation to similar abnormalities reported in the mosquito Aedes aegypti inheriting the Y chromosome meiotic drive haplotype MD. The evolutionary significance of this phenomenon is considered. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 351–359.     

中国马蓝属(爵床科)新组合和新分类群(英文)

采用广义的马蓝属(Strobilanthes Blume)概念,提出3个新组合:匍匐半插花(S.primulifolia(Nees)Y.F.DengJ.R.I.Wood),直立半插花(S.cumingiana(Forst.)Y.F.DengJ.R.I.Wood)和狭叶马蓝(S.atropurpurea var.stenophylla(C.B.Clarke)Y.F.DengJ.R.I.Wood);描述了8新种:南岭马蓝(Strobilanthes austrosinensis Y.F.DengJ.R.I.Wood)、冯氏马蓝(S.fengiana Y.F.DengJ.R.I.Wood)、陶氏马蓝(S.taoana Y.F.DengJ.R.I.Wood)、启无马蓝(S.wangiana Y.F.DengJ.R.I.Wood)、景东马蓝(S.atroviridis Y.F.DengJ.R.I.Wood)、西畴马蓝(S.rostrata Y.F.DengJ.R.I.Wood)、黄连山马蓝(S.spiciformis Y.F.DengJ.R.I.Wood)和匍匐马蓝(S.procumbens Y.F.DengJ.R.I.Wood)。对南岭马蓝、黄连山马蓝、景东马蓝和匍匐马蓝的花粉形态进行了观察。     

Climate change induced hybridization in flying squirrels

There is now unequivocal evidence for global climate change; however, its potential impacts on evolutionary processes remain unclear. Many species have responded to contemporary climate change through shifts in their geographic range. This could lead to increased sympatry between recently diverged species; likely increasing the potential for hybridization. Recently, following a series of warm winters, southern flying squirrels ( Glaucomys volans ) in Ontario, Canada rapidly expanded their northern range limit resulting in increased sympatry with the closely related northern flying squirrel ( Glaucomys sabrinus ). This provided the opportunity to test the prediction that contemporary climate change can act as a catalyst creating conditions for the formation of hybrid zones. Following extensive sampling and molecular analyses (nuclear and mitochondrial DNA), we identified the occurrence of hybridization between sympatric G. sabrinus and G. volans . There was evidence of backcrossing but not of extensive introgession, consistent with the hypothesis of recent rather than historic hybridization. To our knowledge, this is the first report of hybrid zone formation following a range expansion induced by contemporary climate change. This is also the first report of hybridization between North American flying squirrel species.