Cryptic species,gene recombination and hybridization in the genus Spiraeanthemum (Cunoniaceae) from New Caledonia

The Oceanian plant genus Spiraeanthemum (Cunoniaceae) has a centre of diversity in New Caledonia, where it is represented by seven species. Its diversification was investigated using two low‐copy nuclear genes, ncpGS and GapC, and phylogenetic analyses were based on maximum parsimony, maximum likelihood and recombination networks. We detected several cases of gene recombination in both datasets, and these have obscured the history within the genus. For S. ellipticum and S. pubescens, accessions from southern populations on ultramafic soils were genetically distinct from accessions from northern populations on non‐ultramafic soils. Given that no obvious morphological characters distinguish northern and southern populations in either taxon, both may be considered as examples of cryptic species. Incongruence between gene trees and species' delimitation may be explained by the parallel evolution of similar morphology, differential lineage sorting leading to differential fixation of alleles or different introgression patterns in the north and south leading to allele displacement. In New Caledonia, some species with broad ecological preferences may thus be artificial concepts. This suggests that they should be treated more critically in monographs and that the species' richness of the New Caledonian flora may be underestimated. Problems associated with the typification of S. ellipticum and evidence of hybridization events in the history of Spiraeanthemum are also discussed. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 161 , 137–152.     

Selection of candidate coding DNA barcoding regions for use on land plants

An in silico screen of 41 of the 81 coding regions of the Nicotiana plastid genome generated a shortlist of 12 candidates as DNA barcoding loci for land plants. These loci were evaluated for amplification and sequence variation against a reference set of 98 land plant taxa. The deployment of multiple primers and a modified multiplexed tandem polymerase chain reaction yielded 85–94% amplification across taxa, and mean sequence differences between sister taxa of 6.1 from 156 bases of accD to 22 from 493 bases of matK. We conclude that loci should be combined for effective diagnosis, and recommend further investigation of the following six loci: matK, rpoB, rpoC1, ndhJ, ycf5 and accD. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159 , 1–11.     

Changes in the circadian flight activity of the mosquito Anopheles stephensi associated with insemination, blood-feeding, oviposition and nocturnal light intensity

Abstract. The circadian activity patterns of Anopheles stephensi Liston were examined before and after mating and throughout the gonotrophic cycle. In LD 12:12h, males and virgin females are active at dusk. After insemination, females are active at dusk and also for short bursts during much of the night. After blood-feeding, inseminated females are inactive for two nights. On becoming gravid, these females become highly active at dusk and, to a lesser extent, are also active later in the night. In contrast, blood-feeding and egg maturation have minimal effects on the activity pattern of virgin females, who continue to fly only during dusk periods, i.e. virgins continue with the activity pattern which would most likely lead to mating encounters. After oviposition, parous females resume the activity pattern characteristic of inseminated nulliparous females. In a light regime which simulates moonlit nights and normal days, inseminated females are more active overall and flight-burst durations are much longer than in LD 12:12h.     

Influences of edaphic factors on the distribution and abundance of a rare palm (Cyrtostachys renda) in a peat swamp forest in eastern Sumatra,Indonesia

Tropical plant community ecology is often assumed to be driven largely by stochastic disturbance, replacement and demographic processes despite a general lack of information about the physical environment. Tropical soils are more diverse, at regional, intermediate and local scales than usually is recognized. This study was conducted to test hypotheses about the importance of edaphic parameters in determining the abundance and distribution of the rare lipstick palm Cyrtostachys renda Blume and its co‐occurrence with other plants. Eight of 11 tropical tree species were positively associated with C. renda. For Gluta renghas, Shorea parvifolia, Eleiodoxa conferta, Pandanus terrestris and Korthalsia flagellaris, the association with the palm was strong. The palms E. conferta and K. flagellaris appeared to have similar ecological and habitat requirements. The lipstick palm is adapted to specific edaphic conditions related to soil quality and drainage. It prefers fine sand, well‐drained soil and low mineral content, reflected in associations between these variables and stem density, clump density, clump size, frequency, basal area and canopy circle area. High levels of soil Ca^{+ +}, Mg^{+ +} and K⁺ are associated with sites where the palm is absent. The C/N ratio of soils appears to influence palm densities and sizes. All known populations occur in habitats with C/N‐values less than 19, with the largest populations in areas with C/N‐values of 13. Our findings suggest that edaphic variables are important determinants of the abundance and distribution of this tropical peat swamp forest species.     

Effects of intermittent and continuous pheromone stimulation on the flight behaviour of the oriental fruit moth, Grapholita molesta

ABSTRACT. When male oriental fruit moths, Grapholita molesta (Busck) (Tortricidae), casting in clean air entered an airstream permeated with pheromone their flight tracks changed immediately on initial contact with pheromone, but after a few seconds returned to casting as if in clean air. The degree of change in the flight track was directly related to the concentration of pheromone. Although little net uptunnel movement occurred in response to the continuous stimulation provided by a uniformly permeated airstream, when an intermittent stimulus provided by a point-source plume was superimposed onto the permeated airstream moths were able to 'lock on' and zigzag uptunnel in the plume. The percentage of moths doing so corresponded to the difference between the peak concentration within the plume and the background concentration of pheromone permeating the airstream. Moths also locked onto, and flew upwind along the pheromone-clean-air boundary formed along a pheromone-permeated side corridor. Because a similar response was observed along a horizontal edge between a pheromone-permeated floor corridor and clean air, we conclude that the intermittent stimulation at the edge perpetuated the narrow zigzagging response to pheromone.     

Habitat Selection by Prairie Dogs in a Disturbed Landscape at the Edge of Their Geographic Range

ABSTRACT Although habitat attributes of black-tailed prairie dog (Cynomys ludovicianus) colonies have been described for central and northern portions of the species' geographic range, little is known about these associations at the southern edge of this species' distribution. Because high-quality habitats are expected to be scarcer at the edge of the species' geographic range, different patterns of habitat selection might emerge in these populations. We analyzed habitat selection by black-tailed prairie dogs in a human-disturbed mosaic of desert grasslands and shrublands in northwestern Chihuahua, Mexico. We contrasted 151 used and 133 unused habitat units producing 11 case-control logistic regression models to explain site occupancy by prairie dogs with different combinations of environmental variables. Prairie dogs from Chihuahua occupy sites similar in most respects to sites in more northern regions, although these prairie dogs appear to be more tolerant of increased shrub density and reduced herbage cover. We found that site occupancy was best modeled by positive effects of soil moisture level, cover of forbs, cover of unpalatable vegetation, cover of bare ground, and amount of prairie-dog colony area within 1 km and by the inverse of altitude, shrub density, herbage height, and amount of hostile habitat within 1 km. The 2 most significant variables were herbage height and shrub density, which might reflect the prominent role that visibility plays in habitat selection by prairie dogs. In contrast, we found weak evidence that human features have significant impacts on site occupancy by prairie dogs. Our results support the prediction that environmental conditions of sites used by prairie dogs in edge regions partially differ from those observed in more northern latitudes. We suggest that reserve managers focus conservation efforts on areas with short vegetation, low density of shrubs, and high herbage cover, conditions that could be promoted by controlled burns, herbage mowing, and mechanical removal of shrubs.