Wild rabbits in Australia developed genetic resistance to the myxoma virus, which was introduced as a biological control agent. However, little is known about the rate at which this evolutionary change occurred. We collated data from challenge trials that estimated rabbit resistance to myxomatosis in Australia and expressed resistance on a continuous scale, enabling trends in its development to be assessed over 45 years up to 1995. Resistance initially increased rapidly, followed by a plateau lasting ten years, before a second rapid increase occurred associated with the introduction of European rabbit fleas as myxoma virus vectors. By contrast, in the United Kingdom, where rabbit flea vectors were already present when the myxoma virus initially spread, resistance developed more slowly. No estimates of rabbit resistance to myxomatosis have been made for almost 30 years, despite other highly lethal rabbit pathogens becoming established worldwide. Continued testing of wild-caught rabbits in Australia to determine current levels of resistance to myxomatosis is recommended to assess its current effectiveness for managing pest rabbits. Given the economic and environmental significance of invasive rabbits, it would be remiss to manage such biological resources and ecosystem services poorly.

The primary objectives of this research were (1) to characterize intraspecific variation in Powell amaranth seed germination and emergence response to nitrogen fertilization, and (2) to evaluate whether germination and emergence characteristics varied between seeds from populations originating on organic vs. conventional vegetable farms. We hypothesized that nonherbicide–based weed management and use of slower-releasing forms of N on organic farms may have selected for seeds with lower dormancy and lower germination sensitivity to N fertilization than seeds from conventional farms. Seeds were collected from five conventional and five organic vegetable farms in central New York State. A second generation of seeds, produced under common greenhouse conditions and stored for at least 3 mo at 5 C was tested for both germination in petri dishes and emergence in the field under multiple rates of ammonium nitrate (NH4NO3). Both seed germination and emergence were greater for seeds originating from organic compared with conventional vegetable farms. However, seed responsiveness to fertilization did not vary significantly by habitat of origin. Reduced rates or split applications of NH4NO3 significantly reduced emergence in the field in 2003 but had no significant effect on emergence in 2004. Large interpopulation variation in germination and emergence patterns suggests that for Powell amaranth and similar weed species, (1) species-level models of emergence may not be very robust across different farms, and (2) the effectiveness of manipulating emergence through soil fertility practices is likely to vary substantially according to farm and year.

The objectives of this research were to characterize the extent of intraspecifc variation in seed characteristics of Powell amaranth and to evaluate whether such variation was correlated with crop rotation history of the collection sites. We compared characteristics of seeds originating from dairy farms with a corn–alfalfa crop rotation history with seeds originating from farms with a history of intensive vegetable production. We hypothesized that (1) multiple years of perennial alfalfa would select for greater seed dormancy and longevity in seeds of the summer annual Powell amaranth, (2) earlier spring planting dates of corn and alfalfa compared with most vegetable crops would select for earlier emergence, and (3) greater competition and lower soil moisture in the nonirrigated corn–alfalfa rotation would select for greater seed size. Seeds from 10 to 20 plants from each of 10 farms from each habitat were collected in the fall of 2002 and 2003 in central New York. To control for maternal effects on seed dormancy, a second generation of seeds was produced from plants grown under common greenhouse conditions. Germination in petri dishes was greater for second-generation seeds from vegetable farms (46%) than for those from dairy farms (32%). Total emergence following overwinter burial in the field was greater for seeds originating from dairy farms (62%) compared with those from vegetable farms (52%). Neither seed weight nor the rate of emergence varied by habitat of origin. Our results suggest that perennial alfalfa in dairy rotations may have selected for greater dormancy and longevity of Powell amaranth seeds. The large intraspecific variation in seed characteristics observed, underscores the importance of considering multiple populations when making comparisons of germination characteristics across biotyes (e.g., resistant vs. susceptible) or species, or when developing and interpreting models of weed emergence or weed population dynamics.

Lice are obligate parasites of mammals and birds and have become an important model for studies of host-parasite co-evolution and co-phylogenetics. Population genetic and phylogeographic studies represent an important bridge between microevolution and co-phylogenetic patterns. We examine co-phylogeographic patterns in sika deer and their parasitic lice. Co-phylogeographic patterns in deer and lice were evaluated using homologous regions of mitochondrial COI sequences. The phylogeographic breaks recovered for deer populations matched those of previous studies. Comparisons of the phylogeographic tree topology for deer lice with that of their hosts revealed a significant level of congruence. However, comparisons of genetic distances between deer and lice suggested that one of the estimated co-divergence events is more likely a recent host switch. Taking into account genetic divergence, there is not strong evidence for complete phylogeographic co-divergence between deer and their parasitic lice. However, mitochondrial phylogenies only track genetic structure of female lineages, and the incongruence between deer and louse phylogeography may be explained by louse migration mediated by male deer. Morphological analysis of head shape variation based on an elliptic Fourier descriptor showed that overall morphological variation contained phylogenetic signal, suggesting that in general morphology of these lice evolves congruent to population history.

Morphology of both the valves and limbs of several parthenogenetic populations of the widespread non-marine ostracodCryptocandona vavrai Kaufmann (sensu lato) living in groundwater habitats of western (France) and south-eastern Europe(Romania) was examined for the extent of intra- and interpopulational variation. Geometric morphometrics and multivariatestatistics were employed for the description of the valve morphological disparity whereas the discriminant analysis wasperformed for the comparative analysis of the limb chaetotaxy. The ranges of the most studied limb traits principally overlappedamong the populations, however considerable differences in the carapace shape and size, reflecting microevolutionary changes ata macro-scale (inter-population) level, allowed distinguishing quantitatively some Romanian populations which deserve aseparate specific status. Hence, a new species Cryptocandona racovitzai sp. nov. is described which differs from C. vavrai sensustricto mainly in larger size, in more triangular valve shape as seen laterally and in less developed inner lamella of the valves.Finally, after examination of more material from Romanian groundwaters, we hypothesised the presence of more new specieswithin the studied lineage and concluded that Cryptocandona vavrai sensu lato is a polymorphic lineage consisting of severalgeographically differentiated species rather than just only one widely dispersed species.