Recombination landscape dimorphism and sex chromosome evolution in the dioecious plant Rumex hastatulus

There is growing evidence from diverse taxa for sex differences in the genomic landscape of recombination, but the causes and consequences of these differences remain poorly understood. Strong recombination landscape dimorphism between the sexes could have important implications for the dynamics of sex chromosome evolution because low recombination in the heterogametic sex can favour the spread of sexually antagonistic alleles. Here, we present a sex-specific linkage map and revised genome assembly of Rumex hastatulus and provide the first evidence and characterization of sex differences in recombination landscape in a dioecious plant. We present data on significant sex differences in recombination, with regions of very low recombination in males covering over half of the genome. This pattern is evident on both sex chromosomes and autosomes, suggesting that pre-existing differences in recombination may have contributed to sex chromosome formation and divergence. Our analysis of segregation distortion suggests that haploid selection due to pollen competition occurs disproportionately in regions with low male recombination. We hypothesize that sex differences in the recombination landscape have contributed to the formation of a large heteromorphic pair of sex chromosomes in R. hastatulus, but more comparative analyses of recombination will be important to investigate this hypothesis further.This article is part of the theme issue 'Sex determination and sex chromosome evolution in land plants'.Peer reviewe

Women's health groups to improve perinatal care in rural Nepal

BACKGROUND: Neonatal mortality rates are high in rural Nepal where more than 90% of deliveries are in the home. Evidence suggests that death rates can be reduced by interventions at community level. We describe an intervention which aimed to harness the power of community planning and decision making to improve maternal and newborn care in rural Nepal. METHODS: The development of 111 women's groups in a population of 86 704 in Makwanpur district, Nepal is described. The groups, facilitated by local women, were the intervention component of a randomized controlled trial to reduce perinatal and neonatal mortality rates. Through participant observation and analysis of reports, we describe the implementation of this intervention: the community entry process, the facilitation of monthly meetings through a participatory action cycle of problem identification, community planning, and implementation and evaluation of strategies to tackle the identified problems. RESULTS: In response to the needs of the group, participatory health education was added to the intervention and the women's groups developed varied strategies to tackle problems of maternal and newborn care: establishing mother and child health funds, producing clean home delivery kits and operating stretcher schemes. Close linkages with community leaders and community health workers improved strategy implementation. There were also indications of positive effects on group members and health services, and most groups remained active after 30 months. CONCLUSION: A large scale and potentially sustainable participatory intervention with women's groups, which focused on pregnancy, childbirth and the newborn period, resulted in innovative strategies identified by local communities to tackle perinatal care problems

Community mobilisation and health management committee strengthening to increase birth attendance by trained health workers in rural Makwanpur, Nepal: study protocol for a cluster randomised controlled trial

Background: Birth attendance by trained health workers is low in rural Nepal. Local participation in improving health services and increased interaction between health systems and communities may stimulate demand for health services. Significant increases in birth attendance by trained health workers may be affected through community mobilisation by local women's groups and health management committee strengthening. We will test the effect of community mobilisation through women's groups, and health management committee strengthening, on institutional deliveries and home deliveries attended by trained health workers in Makwanpur District. Design: Cluster randomised controlled trial involving 43 village development committee clusters. 21 clusters will receive the intervention and 22 clusters will serve as control areas. In intervention areas, Female Community Health Volunteers are supported in convening monthly women's groups. The groups work through an action research cycle in which they consider barriers to institutional delivery, plan and implement strategies to address these barriers with their communities, and evaluate their progress. Health management committees participate in three-day workshops that use appreciative inquiry methods to explore and plan ways to improve maternal and newborn health services. Follow-up meetings are conducted every three months to review progress. Primary outcomes are institutional deliveries and home deliveries conducted by trained health workers. Secondary outcome measures include uptake of antenatal and postnatal care, neonatal mortality and stillbirth rates, and maternal morbidity

Data from: Do animals living in larger groups experience greater parasitism? A meta-analysis

Parasitism is widely viewed as the primary cost of sociality and a constraint on group size, yet studies report varied associations between group size and parasitism. Using the largest database of its kind, we performed a meta-analysis of 69 studies of the relationship between group size and parasite risk, as measured by parasitism and immune defenses. We predicted a positive correlation between group size and parasitism with organisms that show contagious and environmental transmission, and a negative correlation for searching parasites, parasitoids, and possibly vector-borne parasites (based on the encounter-dilution effect). Overall, we found a positive effect of group size (r=0.187) that varied in magnitude across transmission modes and measures of parasite risk, with only weak indications of publication bias. Among different groups of hosts, we found a stronger relationship between group size and parasite risk in birds than in mammals, which may be driven by ecological and social factors. A meta-regression showed that effect sizes increased with maximum group size. Phylogenetic meta-analyses revealed no evidence for phylogenetic signal in the strength of the group size-parasitism relationship. We conclude that group size is a weak predictor of parasite risk except in species that live in large aggregations, such as colonial birds, where effect sizes are larger

Final Tree used

The phylogenetic tree used in our analysis. This tree is fully dichotomous, includes branch lengths, and has no non-zero branch-lengths. Tree structure and branch lengths were collected from the literature and estimated as described in the methods. The tree was edited in R and Notepad

Morning glory species co-occurrence is associated with asymmetrically decreased and cascading reproductive isolation.

Hybridization between species can affect the strength of the reproductive barriers that separate those species. Two extensions of this effect are (1) the expectation that asymmetric hybridization or gene flow will have asymmetric effects on reproductive barrier strength and (2) the expectation that local hybridization will affect only local reproductive barrier strength and could therefore alter within-species compatibility. We tested these hypotheses in a pair of morning glory species that exhibit asymmetric gene flow from highly selfing Ipomoea lacunosa into mixed-mating Ipomoea cordatotriloba in regions where they co-occur. Because of the direction of this gene flow, we predicted that reproductive barrier strength would be more strongly affected in I. cordatotriloba than I. lacunosa. We also predicted that changes to reproductive barriers in sympatric I. cordatotriloba populations would affect compatibility with allopatric populations of that species. We tested these predictions by measuring the strength of a reproductive barrier to seed set across the species' ranges. Consistent with our first prediction, we found that sympatric and allopatric I. lacunosa produce the same number of seeds in crosses with I. cordatotriloba, whereas crosses between sympatric I. cordatotriloba and I. lacunosa are more successful than crosses between allopatric I. cordatotriloba and I. lacunosa. This difference in compatibility appears to reflect an asymmetric decrease in the strength of the barrier to seed set in sympatric I. cordatotriloba, which could be caused by I. lacunosa alleles that have introgressed into I. cordatotriloba. We further demonstrated that changes to sympatric I. cordatotriloba have decreased its ability to produce seeds with allopatric populations of the same species, in line with our second prediction. Thus, in a manner analogous to cascade reinforcement, we suggest that introgression associated with hybridization not only influences between-species isolation but can also contribute to isolation within a species

APL Pipeline III

APL analysis scripts

Supplementary methods

Describes statistical methods omitted from paper because they were not relevant to the results presented

Final data used

The data used for the phylogenetic meta-analysis in Phylometa. The data file is formatted in accordance with the instructions in the Phylometa manual: it is tab-delimited and the columns are taxon name, taxon-specific effect size, effect size variance, and moderator grouping. In moderator grouping, 0=arachnid, lizard or fish, 1=mammal, 2=bird, and 3=insect