Carbon dioxide and methane measurements from the Los Angeles Megacity Carbon Project - Part 1: calibration, urban enhancements, and uncertainty estimates.

We report continuous surface observations of carbon dioxide (CO) and methane (CH) from the Los Angeles (LA) Megacity Carbon Project during 2015. We devised a calibration strategy, methods for selection of background air masses, calculation of urban enhancements, and a detailed algorithm for estimating uncertainties in urban-scale CO and CH measurements. These methods are essential for understanding carbon fluxes from the LA megacity and other complex urban environments globally.

Spatial and temporal genetic structure in a hybrid cordgrass invasion.

Invasive hybrids and their spread dynamics pose unique opportunities to study evolutionary processes. Invasive hybrids of native Spartina foliosa and introduced S. alterniflora have expanded throughout San Francisco Bay intertidal habitats within the past 35 years by deliberate plantation and seeds floating on the tide.

Hybridization between invasive Spartina densiflora (Poaceae) and native S. foliosa in San Francisco Bay, California, USA.

Rapid evolution in contemporary time can result when related species, brought together through human-aided introduction, hybridize. The significant evolutionary consequences of post-introduction hybridization range from allopolyploid speciation to extinction of species through genetic amalgamation. Both processes are known to occur in the perennial cordgrass genus, Spartina.

Beta SSR loci cross-amplify in five Salsola taxa.

We investigated 20 previously developed Beta SSR markers for their utility in the cross-genera amplification of five morphologically distinct invasive tumbleweed (Salsola) taxa. Of these markers, 17 loci had successful amplification within Salsola taxa. Six loci were polymorphic and were useful in confirming the presence of five genetically distinct Salsola taxa.