Record Chromosome Number in a Mammal?

CROSS has reported^{1, 2} chromosome complements in rodents ranging up to 2n=84 (in the North American geomyid Geomys breviceps) and 2n=86 (in the heteromyid Dipodomys merriami). Matthey has contested³ this claim; he maintained that in Geomys bursarius 2n =70 or 72 and he doubted whether a higher number had been confirmed. Numbers in the 2n=70 to 80 range have since been reported⁴ in several genera of Canidae and Ursidae. In general, rodent chromosomes fall into the lower group numbers but, among murines, Lophuromys aquillus is reported to have a chromosome complement of 70 (ref. 5) and Cricetomys gambianus one of 78 (ref, 6). In the gerbilline, Meriones shawii, the number can vary up to 78 (ref. 7).     

The ecology and economics of damage to Brassicae by wood-pigeons Columba palumbus

Damage caused by wood-pigeons, Columba palumbus, to spring cabbage and Brussels sprouts was measured during three winters in two areas in the Vale of Evesham, Worcestershire. In one area (experimental) special attempts were made to reduce pigeon damage in addition to the normal efforts of the growers. In the other (control) area no such additional measures were taken. There was slightly more damage in 1969-70, but low market prices made it less important than in 1968-9 or 1970-1. There was no significant difference in any season between the damage in the control and experimental areas. No damage was caused to Brussels-sprout buttons as the birds ate only the tops of the plants; they preferred Brussels sprouts to cabbages and it is likely that the presence of the former helped to reduce the amount of damage to nearby cabbage fields. The amount of damage was not correlated with the amount spent on crop protection; actual damage was not correlated with the grower's estimates in the control area. In the second season a very intensive shooting campaign in the experimental area did not result in less damage, but the movements of local inhabitants and farm workers near a village did afford protection. The significance of the damage in the Vale and elsewhere is assessed in relation to the economics of crop production, the cropping pattern for cabbages and the behaviour and ecology of the wood-pigeon.     

OBSERVATIONS AND EXPERIMENTS ON THE HESSIAN FLY (MAYETIOLA DESTRUCTOR SAY)

Experiments showed that a stem midge collected locally on couch grass ( Agropyron repens ) and similar midges collected on wheat, barley and rye were of the same species, i. e. the hessian fly, Mayetiola destructor Say. There were three main flights per year, with some overlapping of the generations. In experiments, Aegilops ovata, Triticum compactum, T. dicoccoides, T. durum, T. spelta and T. turgidum were successfully used as host plants besides wheat, barley, rye and couch grass. Individual female midges when moved from plant to plant gave rise to families on the different host plants; similarly, succeeding generations of midges were able to breed on various host plants other than those from which they themselves were reared. Oviposition also took place on plants on which larvae failed to establish themselves.
Wheat seemed more favourable for the hessian fly than couch grass, and more midges were reared from young plants than from mature ones.
Unisexual families occurred in about half the experiments. The following parasites were bred: Trichacis didas Walker, Eupteromalus? hemipterus Walker, Platygaster sp., Chrysocharis sp. and Tetrastichus sp.     

Can Lactobacillus spp. Be a Factor Reducing the Risk of Miscarriage?

Pregnancy loss is a common obstetric problem. Significant causes of miscarriage include genetic and epigenetic disorders of the embryo, immunological and endocrine factors, uterine malformations, improper embryo selection, and lifestyle. Perhaps a hitherto underappreciated cause of miscarriage may be an abnormal microbiota composition of the female reproductive system. Lactobacillus spp. is the most common bacteria within the reproductive tract. However, the protective role of Lactobacilli in the vagina has been well described in the literature, while it is still unknown what function Lactobacilli may have in the uterus. Moreover, new research shows that Lactobacillus spp. can have a role in miscarriage. However, both molecular and immunological mechanisms of host-Lactobacillus spp. interactions are not fully understood. Understanding these relationships will help address the importance and extent of the protective role of Lactobacillus spp. in miscarriage.     

Phylogenetic relationships in the subgenus Mus (genus Mus, family Muridae, subfamily Murinae): examining gene trees and species trees

Over eight kilobases (kb) of sequence from eight genes including two mitochondrial loci, Cyt b and 12S, and six nuclear loci, B2m , Zp3 , Tcp1, Sry, Smcx and Smcy , were used to investigate phylogenetic relationships among 11 taxa representing eight species within the rodent genus Mus . Particular attention was given to discerning relationships among species within the subgenus Mus including members of a Palearctic clade ( M. musculus , M. spicilegus , M. macedonicus and M. spretus ) and members of an Asian clade ( M. caroli , M. cookii and M. cervicolor ), as previous studies using different datasets have produced different topologies for taxa within these two groups. While parsimony analyses of the combined eight-gene dataset yielded a single, fully resolved tree, support values were lower for nodes resolving relationships within the Palearctic and Asian clades than they were elsewhere in the tree. In addition, a maximum likelihood analysis of the same eight-gene dataset yielded different topologies for both the Palearctic and the Asian clades. Both observations are indicative of clade instability. The nature of this instability was explored through a comparison with our previous study in which we included the two mitochondrial loci and only four of the six nuclear genes, and through an analysis of partitioned data, specifically mitochondrial vs. nuclear genes. This study underscores the importance of considering among-site rate variation in phylogeny reconstruction. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 84 , 653–662.     

Plasticity of moult and breeding schedules in migratory European Stonechats Saxicola rubicola

Timing is crucial in seasonal environments. Passerine birds typically use a combination of physiological mechanisms and environmental cues to ensure that breeding, moult and migration occur without major temporal overlap and under the most favourable conditions. However, late in the breeding season some individuals initiate additional clutches , whereas others initiate moult. Such alternative strategies are thought to reflect trade‐offs between reproductive benefits and timely investment in maintenance and survival. The degree of seasonal plasticity differs between species, depending on the mechanisms that govern their annual routine. Migrants are generally under pressure to complete breeding and moult before the autumn departure and often show little plasticity. We studied seasonal plasticity of breeding and moult schedules in the European Stonechat Saxicola rubicola. This species, an obligate short‐distance migrant in Central Europe, sometimes initiates late clutches after typically at least two earlier breeding attempts. Based on life‐history theory and on observations in captivity, which revealed photoperiodic regulation of breeding and moult, we predicted relatively little seasonal plasticity in Stonechats. We further predicted that reproductive gains of late breeders should be offset by reduced survival. These predictions were tested on long‐term field data, using Underhill–Zucchini models to estimate moult. Late breeding occurred in c. 40% of pairs and increased their reproductive success by a third. Both sexes modified moult timing but in different ways. Late breeding females postponed moult approximately until chick independence without compensating for delay by faster moult. Males started moult on time and overlapped it with breeding, associated with markedly slowed plumage change. Sex differences in moult score increased with lay date, but due to their respective modifications, both sexes delayed moult completion. Nonetheless, we could not detect any evidence for survival costs of late breeding. Breeding and moult of European Stonechats appear relatively flexible, despite migratory schedules and photoperiodic programs for seasonal timing. Individuals can modify seasonal behaviour in late summer, presumably depending on their condition, and may profit considerably from extended breeding.