Meiotic drive at the Om locus in wild-derived inbred mouse strains

Meiotic drive is an evolutionary force in which natural selection is uncoupled from organismal fitness. Recently, it has been proposed that meiotic drive and genetic drift represent major forces in the evolution of the mammalian karyotype. Meiotic drive involves two types of genetic elements, Responders and Distorters , the latter being required to induce transmission ratio distortion at the former. We have previously described the Om meiotic drive system in mouse chromosome 11. To investigate the natural history of this drive system we have characterized the alleles present at the distorter in wild-derived inbred strains. Our analysis of transmission of maternal alleles in both classical and wild-derived inbred strains indicated that driving alleles are found at high frequency in natural populations and that the existence of driving alleles predates the split between the Mus spicilegus and M. musculus lineages.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 84 , 487–492.     

Underground starch storage in Erica species of the Cape Floristic Region – differences between seeders and resprouters

Concentrations of starch in roots of seeder species of Erica from the Cape Floristic Region, South Africa were found to be considerably less than in resprouters. Shoot starch was highly variable but mean values were similar in both seeder and resprouter species of Erica . Three distinct patterns of starch storage in roots were recognized. All seeder species fell within definitions of Categories 1 (narrow major and minor parenchymatous rays, one to two cells wide with no inter-ray storage) or 2 (thick major rays up to seven cells wide and thin minor rays with small amounts of inter-ray storage) whereas resprouter species were consistently within Categories 2 or 3 (broad major and minor rays, up to eight cells wide and conspicuous inter-ray starch storage). Results are discussed in light of similar studies of the related Epacridaceae. 'Mixed' species (i.e. with seeder or resprouter individuals present, often in distinct populations) were always classified as belonging to Category 2. Studies of populations of three 'mixed' species confirmed that seeder forms had consistently lower amounts of root starch than resprouters. Rays of xylem parenchyma were the main sites for starch storage in roots of both seeders and resprouters and greater proportions of cross-sectional area of roots were consistently devoted to such storage tissues in resprouter forms of the three 'mixed' species. Analyses of a number of seeder and resprouter Erica coccinea populations showed that differences in amounts of realised and potential root starch storage are best explained by the effect of regeneration behaviour rather than by among-population variability.     

Nutritional versus genetic correlates of caste differentiation in a desert ant

1. In many ant species, caste differentiation stems from trophic differences at the larval stage. Adult workers that feed larvae have great control over the allocation of colony resources to growth (production of workers) versus reproduction (production of queens). However, larval caste fate may also be constrained very early on through direct genetic effects or non‐genetic maternal effects. 2. Here, we combined isotopic and genetic analyses to study the developmental origin of queens and workers in a desert‐dwelling ant, Cataglyphis tartessica (Amor & Ortega, 2014). Queens do not found new colonies alone but rather disperse with workers. As the latter are always wingless, selection pressures on specific queen traits such as flight ability have become relaxed. Though the phylogenetically related species, C. emmae (Forel, 1909) only produces winged queens much larger than workers, C. tartessica produces two types of small queens relative to workers: brachypterous (short‐winged) queens and permanently apterous ergatoid (wingless and worker‐like) queens. 3. Upon emergence, workers and ergatoids have similar δ15N isotopic values, which were lower than those of brachypters, suggesting the latter are fed more protein as larvae. Microsatellite analyses indicated that: (i) colonies are mostly monogynous and monandrous; (ii) both ergatoids and brachypters are equally related to workers; and (iii) in the few polyandrous colonies, patrilines were evenly represented across workers, brachypters and ergatoids. 4. Overall, there was no evidence of genetic caste determination. We suggest that, in contrast to brachypters, ergatoids are selfish individuals that escape the nutritional castration carried out by workers and develop into queens in spite of the colony's collective interests.     

Spring migratory routes of eight trans-Saharan passerines through the central and western Mediterranean; results from a network of insular and coastal ringing sites

Detailed information on spring migration routes of songbirds across the Mediterranean is still scanty. Results are presented here from a study on the occurrence of eight Palaearctic-African migrants across the western and central Mediterranean based on ringing data collected during the Progetto Piccole Isole, a co-ordinated project based on standardized mist netting at 21 islands and coastal stations. The species were Melodious Warbler Hippolais polyglotta , Icterine Warbler Hippolais icterina, Bonelli's Warbler Phylloscopus bonelli , Wood Warbler Phylloscopus sibilatrix , Pied Flycatcher Ficedula hypoleuca , Collared Flycatcher Ficedula albicollis , Red-backed Shrike Lanius collurio and Woodchat Shrike Lanius senator . Their capture frequencies were expressed as the frequency of each species relative to the total number of migrants ringed at each station in order to correct for differences in capture effort between stations. For most species, the detailed, quantitative results confirmed the scanty information available so far, whereas in the case of Melodious Warbler and Bonelli's Warbler, evidence of undescribed and unexpected migration routes was found. These results suggest that standardized mist netting provides an important method for studying the migratory routes of small birds, in particular for those species which are not frequently ringed in their breeding and wintering grounds.     

The function of aggressive chases by breeding Black and Red Kites Milvus migrans and M. milvus during the post-fledging dependence period

Black and Red Kites Milvus migrans and M. milvus chase other raptors approaching their nests. The study of this behaviour during the post-fledging period suggested that it reflects mainly, but not only, anti-predator behaviour. The frequency of vigilance and aggressive chases decreased through the post-fledging period as predicted by theoretical models of nest defence. Although predation risks were similar, Black Kites invested more time chasing intruders than did Red Kites. Black Kites, unlike Red Kites, chased away intruding juveniles, which may be interpreted as a behaviour to avoid investment in unrelated fledglings. Black Kites usually nest in loose colonies where the risk of, and selection pressures against, accidental investment in unrelated fledglings is likely to be greater than for Red Kites. Differences in aggressive chases by Black and Red Kites are better related to this than to different predation risks.     

Immunocytochemical Staining For the C-Erbb-2 Gene Product In Breast Aspirates: A Preliminary Report

The results of the determination of c-erbB-2 gene expression by immunocytochemical staining of cytological aspirates, prepared by cytocentrifugation, have been compared with paraffin-embedded tissue sections from the same tumour. Our results show equivalent staining in 20/22 cases, with six cases being both scored positive and fourteen cases being both negative. Two samples gave conflicting results. One case was scored as being positive on the cytological aspirate, whereas in the tissue sections taken from the same tumour positive staining was only seen in areas of non-invasive intraduct carcinoma. This sample was scored as being negative. In another case, cytoplasmic staining with less than 50% of the cells showing any positivity was observed in the cytospin sample, with negative staining in the corresponding tissue section. We conclude that expression of c-erbB-2 immunostaining is detectable on cytological preparations prepared by cytocentrifugation but must be interpreted with caution in tumours which may have a large intraduct component or which give predominant cytoplasmic staining.     

Eimeria diminuta sp. n. from the Ceylon Jungle Fowl,Callus lafayettei*

SYNOPSIS. Eimeria diminuta sp. n. is described from the Ceylon jungle fowl Gallus lafayettei. Its sporulated oocysts are 16.5 (16–17.5) × 14.5 (13.5 × 15.5) μm. The species produces patent infections in domestic fowl.     

Effects of sacbrood virus on adult honey-bees

Much sacbrood virus accumulates in the brains of infected bees, especially of drones, without causing symptoms. However, infected individuals fly earlier in life than healthy bees and most infected foragers fail to collect pollen, as do bees briefly anaesthetized with CO₂. The few infected bees that gather pollen contaminate their loads with much sacbrood virus. Infection does not shorten the lives of drones, or of workers that have been deprived of pollen, but it much shortens the prolonged lives of workers that have eaten pollen. Infected workers, healthy workers deprived of pollen, and senile individuals are unable to maintain the usual metabolic rates of bees at temperatures below 35^oC, or to resist chilling.