Evaluation of a modern-analogue methodology for reconstructing Australian palaeoclimate from pollen

Quantitative palaeoclimate reconstructions are widely used to evaluate climatemodel performance. Here, as part of an effort to provide such a data set for Australia, we examine the impact of analytical decisions and sampling assumptions on modern-analogue reconstructions using a continent-wide pollen data set. There is a high degree of correlation between temperature variables in the modern climate of Australia, but there is sufficient orthogonality in the variations of precipitation, summer and winter temperature and plant–available moisture to allow independent reconstructions of these four variables to be made. The method of analogue selection does not affect the reconstructions, although bootstrap resampling provides a more reliable technique for obtaining robust measures of uncertainty. The number of analogues used affects the quality of the reconstructions: the most robust reconstructions are obtained using 5 analogues. The quality of reconstructions based on post-1850 CE pollen samples differ little from those using samples from between 1450 and 1849 CE, showing that European post settlement modification of vegetation has no impact on the fidelity of the reconstructions although it substantially increases the availability of potential analogues. Reconstructions based on core top samples are more realistic than those using surface samples, but only using core top samples would substantially reduce the number of available analogues and therefore increases the uncertainty of the reconstructions. Spatial and/or temporal averaging of pollen assemblages prior to analysis negatively affects the subsequent reconstructions for some variables and increases the associated uncertainties. In addition, the quality of the reconstructions is affected by the degree of spatial smoothing of the original climate data, with the best reconstructions obtained using climate data froma 0.5° resolution grid, which corresponds to the typical size of the pollen catchment. This study provides a methodology that can be used to provide reliable palaeoclimate reconstructions for Australia, which will fill in a major gap in the data sets used to evaluate climate models

Genetic variation in British Campanula rotundifolia L.

The harebell (Campanula rotundifolia) is a short‐lived perennial native to the British Isles, where tetraploid, hexaploid and (rarely) pentaploid types occur. The hexaploid and tetraploid cytotypes show geographic separation; hexaploids are largely restricted to Ireland and the west coast of Britain. Here, we analyse morphometric and molecular genetic variation in harebell populations from across Britain and from three European locations, and assess quantitative genetic variation in phenology through a common garden trial, to determine levels of diversity and divergence, and test whether phenotypic divergence is associated with geographic variation in environment. Morphometric analysis resolves tetra‐ and hexaploids. Molecular data supported the separation of the cytotypes, with unique chloroplast DNA haplotypes in each cytotype and nuclear ITS data showing a single haplotype for hexaploids but numerous haplotypes in tetraploids. The molecular divergence between cytotypes suggests possible different origins and invasion pathways since the last glacial maximum

Can genetic bar-coding be used to identify aquatic Ranunculus L. subgenus Batrachium (DC) A. Gray? A test using some species from the British Isles

Aquatic Batrachium Ranunculus species are a key component of river macrophyte communities selected for protection under European Union legislation. The group’s simplified morphology and variable taxonomic interpretation often makes identification to species level very difficult. A genetic approach was trialled as an alternative, more reliable, means of identification. DNA barcoding using four markers (chloroplast and nuclear) was tested. The chloroplast sequence trnH-psbA worked best and allowed identification of three out of five species while nuclear sequences supported the identification of two hybrids. This method is amenable to simplification through techniques such as PCR-RFLP or RT-PCR. It has the potential to provide easy, rapid and inexpensive identification of Batrachium Ranunculus species

Grazing alters insect visitation networks and plant mating systems

* Many flowering plant species have a facultative or obligate dependence on insect pollination for reproductive success. Anthropogenic disturbance may alter these species interactions, but the extent to which structural changes to plant-pollinator networks affect plant species mating systems is not well understood. * We used long-term livestock grazing of a birch wood ecosystem to test whether disturbance of this semi-natural habitat altered floral resources, the structure of plant–insect visitation networks and the mating system of a focal plant species, Cirsium palustre. * Grazed habitat had a higher species richness of floral resources for pollinators. Visitation networks in grazed habitats were larger, more diverse, with an increase in the number of pollinators per plant species. Controlling for sampling effects, however, showed networks in grazed habitats were less nested and revealed a positive correlation between network connectance and floral species richness. * Network connectance was negatively related to C. palustre outcrossing rate within grazed and ungrazed sites. However, on average, the effects of grazing, including greater mean connectance, produced higher overall outcrossing rates and more pollen donors compared with ungrazed habitat. The number of different pollen donors, spatial genetic structure and mating among close relatives were all correlated with greater extent of suitable C. palustre habitat in the landscape, consistent with the effects of increasing plant population size but limited seed dispersal. * Pre-adaptation of C. palustre to disturbance coupled with a preponderance of highly dispersive flies attracted to the greater food resources in grazed habitat is a likely mechanism underpinning this increased pollen transport. * Habitat modification by long-term mammalian grazing fundamentally shifted visitation network structure and the state of a plant mating system, indicating how ecosystem disturbance can cascade across levels of biological organization through altered interspecific interactions. Cirsium palustre retains flexibility to bias reproduction towards selfing where pollen donor diversity is limited; such reproductive flexibility may be an important mechanism structuring plant populations in human-modified landscapes

Dataset associated with the manuscript in prep Wachowiak W, Telford A, Zucca GM, Gonzalez-Martinez SC, Cavers S. 2014. Do local adaptation and speciation involve the same genes in recently diverged taxa?

Dataset associated with the manuscript in prep Wachowiak W, Telford A, Zucca GM, Gonzalez-Martinez SC, Cavers S. 2014. Do local adaptation and speciation involve the same genes in recently diverged taxa

Does geographic origin dictate ecological strategies in Acacia senegal (L.) Willd.?: evidence from carbon and nitrogen stable isotopes

Background and aims: Acacia senegal, a leguminous dryland tree, is economically and ecologically important to sub-Saharan Africa.Water-use efficiency (WUE) and biological nitrogen fixation (BNF) are fundamental to plant productivity and survival.We quantify provenance differences in WUE, BNF, photosynthesis, biomass and gum arabic production from A. senegal assessing genetic improvement potential. Methods: Using stable isotope ratios, we determined WUE (δ13C) and BNF (δ15N) from provenances of mature A. senegal in field-trials (Senegal), sampling leaves at the beginning (wet) and end (dry) of the rainy season. Seedling provenance trials (UK) determined photosynthesis, and biomass and δ13C in relation to water table. Environmental data were characterised for all provenances at their sites of origin. Results: Provenances differed in both δ13C and δ15N. Gum yield declined with increasing WUE. Virtually no BNF was detected during the dry season and seedlings and mature trees may have different WUE strategies. Wind speed and soil characteristics at provenance origin were correlated with isotope composition and gum production. Conclusion: Provenance differences suggest that selection for desirable traits, e.g., increased gum production, may be possible. As ecological strategies relate to native locality, the environmental conditions at plantation site and provenance origin are important in assessing selection criteria