Plant connectivity underlies plant-pollinator-exploiter distributions in Ficus petiolaris and associated pollinating and non-pollinating fig wasps

Peer reviewedPostprin

Transcriptome-Facilitated Development of SNPs for the Sonoran Desert Rock Fig, Ficus petiolaris (Moraceae)

Premise of the study: Single-nucleotide polymorphism (SNP) primers were developed for a native North American desert fig, Ficus petiolaris (Moraceae), to provide markers for population genetic studies designed to quantify patterns of gene flow across a complex landscape. Methods and Results: Transcriptome sequencing and bioinformatic protocols were implemented to discover SNPs in single-copy protein-coding genes. Multiplexes of 30 nuclear and 24 organellar (chloroplast and mitochondrial) SNPs were selected for primer development and genotyping on the Sequenom MASSArray System. Of these 54 loci, 49 reliably amplified across a panel of 96 F. petiolaris individuals. Conclusions: This study has provided SNP primers that can be applied in future studies investigating population genetics of F. petiolaris and its coevolution with associated pollinating and nonpollinating fig wasps

Exchange rates and fundamentals: a generalization

Exchange rates have raised the ire of economists for more than twenty years. The problem is that few, if any, exchange rate models are known to systematically beat a naive random walk in out-of-sample forecasts. Engel and West (2005) show that these failures can be explained by the standard present value model (PVM) because it predicts random walk exchange rate dynamics if the discount factor approaches one and fundamentals have a unit root. This paper generalizes the Engel and West hypothesis to the larger class of open economy dynamic stochastic general equilibrium (DSGE) models. The Engel and West hypothesis is shown to hold for a canonical open economy DSGE model. We show that all the predictions of the standard PVM carry over to the DSGE PVM. The DSGE PVM also yields unobserved components (UC) models that we estimate using Bayesian methods and a quarterly Canadian-U.S. sample. Bayesian model evaluation reveals that the data support a UC model that calibrates the discount factor to one, implying the Canadian dollar–U.S. dollar exchange rate is a random walk dominated by permanent cross-country monetary and productivity shocks.Foreign exchange rates

The present-value model of the current account has been rejected: Round up the usual suspects

Tests of the present-value model of the current account are frequently rejected by the data. Standard explanations rely on the "usual suspects" of nonseparable preferences, shocks to fiscal policy and the world real interest rate, and imperfect international capital mobility. The authors confirm these rejections on postwar Canadian data, then investigate their source by calibrating and simulating alternative versions of a small open economy, real business cycle model. Monte Carlo experiments reveal that, although each of the suspects matters in some way, a "canonical" RBC model moves closest to the data when it features exogenous world real interest rate shocks.Balance of payments ; International finance ; Econometric models

Trade-offs and coexistence: A lottery model applied to fig wasp communities

Ecological communities in which organisms complete their life cycles on discrete ephemeral patches are common and often support an unusually large number of species. Explaining this diversity is challenging for communities of ecologically similar species undergoing preemptive competition, where classic coexistence mechanisms may not readily apply. We use nonpollinating fig wasps as a model community characterized by high diversity and preemptive competition to show how subadditive population growth and a trade-off between competitor fecundity and dispersal ability can lead to coexistence. Because nonpollinator species are often closely related, have similar life histories, and compete for the same discrete resources, understanding their coexistence is challenging given competitive exclusion is expected. Empirical observations suggest that nonpollinating fig wasp species may face a trade-off between egg loads and dispersal abilities. We model a lottery in which a species’ competitive ability is determined by a trade-off between fecundity and dispersal ability. Variation in interpatch distance between figs generates temporal variability in the relative benefit of fecundity versus dispersal. We show that the temporal storage effect leads to coexistence for a range of biologically realistic parameter values. We further use individual-based modeling to show that when species’ traits evolve, coexistence is less likely but trait divergence can result. We discuss the implications of this coexistence mechanism for ephemeral patch systems wherein competition is strongly preemptive

Genetic diversity and population structure of the threatened temperate woody bamboo Kuruna debilis (Poaceae: Bambusoideae: Arundinarieae) from Sri Lanka based on microsatellite analysis

Species of the temperate woody bamboo genus Kuruna Attigala, Kathriar. & L.G. Clark (Poaceae: Bambusoideae) distributed in Sri Lanka and southern India, are threatened due to deforestation and habitat fragmentation. The current study focused on the tetraploid woody bamboo Kuruna debilis (Thwaites) Attigala, Kathriar. & L.G. Clark, using twelve variable microsatellite loci to assess the genetic diversity and population structure in six known Sri Lankan populations. Due to the rarity of the species, an exhaustive sampling of accessible plants resulted in a total of only 28 individuals. Nonetheless, the allelic diversity was high at most loci and given the limited distances separating populations (\u3c 65 km apart), they exhibited a fairly high genetic differentiation (FST = 0.113) and strong isolation by distance. Structure, neighbour-joining, and neighbour-net analyses concur in grouping the six K. debilis populations into three genetic clusters consistent with the spatial proximity of the populations: one cluster comprised populations from the Piduruthalagala Mountain and Horton Plains, the second cluster consisted of the population from Adams Peak and the last comprised the populations from the Handapan Ella Plains. Due to multiple indicators of high allelic diversity, the population from the northern Horton Plains (LA124) should be targeted for conservation. Moreover, the population found in Adams Peak (LA159) is also genetically important and critical to the conservation of these species due to its unique genetic diversity. As the first population genetics study of Bambusoideae in Sri Lanka, we anticipate that our results will provide a foundation for future comparative population genetics and conservation studies in the country

Phenotypic Plasticity of Native vs. Invasive Purple Loosestrife: A Two-state Multivariate Approach

The differences in phenotypic plasticity between invasive (North American) and native (German) provenances of the invasive plant Lythrum salicaria (purple loosestrife) were examined using a multivariate reaction norm approach testing two important attributes of reaction norms described by multivariate vectors of phenotypic change: the magnitude and direction of mean trait differences between environments. Data were collected for six life history traits from native and invasive plants using a split-plot design with experimentally manipulated water and nutrient levels. We found significant differences between native and invasive plants in multivariate phenotypic plasticity for comparisons between low and high water treatments within low nutrient levels, between low and high nutrient levels within high water treatments, and for comparisons that included both a water and nutrient level change. The significant genotype × environment (G × E) effects support the argument that invasiveness of purple loosestrife is closely associated with the interaction of high levels of soil nutrient and flooding water regime. Our results indicate that native and invasive plants take different strategies for growth and reproduction; native plants flowered earlier and allocated more to flower production, while invasive plants exhibited an extended period of vegetative growth before flowering to increase height and allocation to clonal reproduction, which may contribute to increased fitness and invasiveness in subsequent years

Development and Characterization of Microsatellite Loci for Ficus hirta (Moraceae)

Microsatellite primers were developed to investigate population genetic structure in Ficus hirta (Moraceae). Sixteen microsatellite primers were developed and optimized for F. hirta using Illumina paired-end sequencing of pre-receptive and receptive developmental-phase female flowers. Out of 16 primers, nine were found to be polymorphic in four populations of F. hirta. Alleles per locus ranged from two to 15 across the 94 F. hirta individuals, while within-population observed and expected heterozygosity per locus ranged from 0.000 to 0.955 and from 0.000 to 0.882, respectively. In addition, the 16 primers were tested in 29 additional Ficus species, with all found to amplify in at least 11 of these species and with most amplifying in a majority of the species. This set of microsatellite primers is the first specifically developed for F. hirta and will facilitate studies of genetic diversity within and genetic differentiation among populations of Ficus species

Measuring the Effectiveness of Isolation of Brassica napus L. Accessions During Caged Germplasm Regeneration

Gene flow, which is the successful movement of genes among populations by mating or migration of seeds or other propagules, has gained much interest in agriculture in recent years because of the widescale adoption of transgenic crops and concerns over transgene escape into the wild (James 2004; Messeguer 2003; Stewart et al. 2003). Brassica napus (rapeseed), together with maize and sugar beet, have been identified among the species for which cross-pollination and transgene escape are concerns (Treu and Emberlin 2000)