Bimodal karyotype in Cynomorium coccineum L. and its systematic implications

The presence of a bimodal karyotype in Cynomorium coccineum (2n = 28) is used to support its separation from Balanophoraceae and the maintenance of Cynomoriaceae as a separate family.     

Scaling-up knowledge of growing-season net ecosystem exchange for long-term assessment of North Dakota grasslands under the Conservation Reserve Program

Scaling‐up knowledge of land‐atmosphere net ecosystem exchange (NEE) from a single experimental site to numerous perennial grass fields in the Northern Great Plains (NGP) requires appropriate scaling protocols. We addressed this problem using synoptic data available from the Landsat sensor for 10 growing seasons (April 15 to September 30) over a North Dakota field‐site, where we continuously measured CO₂ exchange using a Bowen Ratio Energy Balance (BREB) system. NEE observed during the growing season at our field‐site from 1997 to 2006 vacillated with drought and deluge, with net carbon (C) losses to the atmosphere in 2006. We used stepwise linear regression with 10 years of Landsat and NEE data to construct and validate a model for estimating grassland growing‐season NEE from field to landscape scales. Eighty‐nine percent of the variability in NEE was explained by year, live biomass, carbon : nitrogen ratio, day of image acquisition, and annual precipitation. We then applied this model on 20 620 ha of North Dakota perennial grass fields enrolled in the Conservation Reserve Program (CRP), including 1272 fields east of the Missouri River and 165 fields west‐river. Growing‐season NEE for individual CRP fields was highly variable from 1997 to 2006, ranging from ?366 to 692 g C m^?2 growing season^?1. Mean annual growing‐season fluxes over 10 years for CRP fields located east‐river and west‐river were 317 g C m^?2 growing season^?1 and 239 g C m^?2 growing season^?1, respectively. Average cumulative growing‐season NEE modeled for fields east‐ and west‐river diverged from one another in 2002–2006, when west‐river fields received < 70% of the long‐term annual average precipitation during these years. Results indicate assessment of conservation practices on grassland CO₂ exchange during the growing season can be remotely estimated at field and landscape scales under variable environmental conditions and should be followed up with similar, spatially explicit investigations of NEE during the dormant season.     

Examining growth rate and starvation endurance in pit‐building antlions from Mediterranean and desert regions

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The effect of sand depth,feeding regime,density, and body mass on the foraging behaviour of a pit‐building antlion

Abstract 1. Pit‐building antlions are small sit‐and‐wait arthropod predators, which dig conical pits in sandy soils. We studied how biotic (conspecific density and feeding regime) and abiotic (sand depth) factors affect pit diameter and depth, while taking into account the larval body mass. 2. Pit diameter increased with larval body mass at a decelerating rate. In addition, larger larvae tended to relocate less frequently than smaller ones. 3. Sand depth positively affected overall pit size, while increasing conspecific density had a weaker but negative effect on pit size. 4. Feeding the antlions resulted in an increase in pit diameter compared with an unfed control group. However, as prey size increased this positive effect diminished. This result suggests that the existence of prey provides information about the quality of the microhabitat, triggering pit extension. However, similarly to the reduction in the foraging effort of saturated predators, antlions provided with large prey invested only little effort in pit enlargement. 5. Antlions were previously shown to be sensitive to prey and conspecific vibrations in the sand. We thus expected the feeding regime of the neighbour to affect antlion behaviour – surrogate of discriminating between local and global shortage of prey. Nevertheless, antlions with fed neighbours (a local prey shortage) did not show different behaviour compared with a control group in which both antlions were unfed (a global prey shortage).     

Effect of spatial pattern and microhabitat on pit construction and relocation in Myrmeleon hyalinus (Neuroptera: Myrmeleontidae) larvae

Abstract.  1. In two sets of enclosure experiments, we studied the spatial pattern, relocation rates, pit construction rates, and microhabitat preference of Myrmeleon hyalinus larvae.
2. We showed that M. hyalinus larvae actively prefer shady sites and often relocate to shady areas when exposed to the sun. This behaviour may constitute a life-saving strategy in desert environments.
3. The initial spatial pattern in a cluster of antlion larvae did not affect the final pattern, relocation rate, or the pathway moved while relocating. We interpret this finding to mean that the spatial pattern of M. hyalinus larvae is mainly influenced by factors operating at large time-scales, such as exploitation competition and physical-microclimatological constraints, rather than those operating at shorter time-scales, such as interference competition.
4. In contrast, the likelihood of pit construction was positively correlated with nearest neighbour distance, possibly as a result of interference competition.
5. Pit construction rates were constant throughout the experiment, while relocation rates decreased with time.
6. Contrary to previous studies, we found no correlation between body mass and spatial position inside the cluster, suggesting that these differences are the products of slower processes (e.g. exploitation and body condition).     

Swimming out of Africa: mitochondrial DNA evidence for late Pliocene dispersal of a cichlid from Central Africa to the Levant

The rich Levantine fauna and flora were shaped by millions of years of migration across the region, from Africa to Eurasia and vice versa. Most large-scale processes that led to this diversity have been relatively well studied. However, small-scale processes, and details such as the area of origin of particular groups, and the route and time of dispersal are often not as clear. This is the case with the endemic Levantine representatives of the fish family Cichlidae. In this work we combine genetic, palaeontological and geological data in an attempt to understand the dispersal of the cichlid fish Astatotilapia flaviijosephi (Lortet, 1883) from sub-Saharan Africa to the Levant. A. flaviijosephi is unique among the Levantine cichlids in being the only non-tilapiine. It is also the only haplochromine cichlid to be found out of Africa. A partial sequence of the control region of the mitochondrial DNA was used to determine A. flaviijosephi 's phylogenetic relationships with other African haplochromines, and to estimate its time of divergence from this group. Combining our findings with palaeontological and geological data, we suggest that A. flaviijosephi separated from the other haplochromines during the middle to late Pliocene (2.5–3.3 Mya) and probably dispersed from Africa to the Levant via the Nile.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 82 , 103–109.     

Tracking palustrine water seasonal and annual variability in agricultural wetland landscapes using Landsat from 1997 to 2005

Wetlands densely populate the ecoregion transecting the center of the Prairie Pothole Region (PPR) known as the Missouri Coteau and epicenter to the most productive waterfowl‐breeding habitat in North America. These palustrine, depressional basin waters vacillate with regional drought and deluge, so surface water fluctuations over time modulate wetland productivity, habitat, and water quality functions. Models predict formidable effects of climate change on glacial basin surface waters, yet large‐scale, long‐term observation data are lacking to compare against predicted changes. Current, optical‐based water detection models do not delineate marsh vegetation from shallow, turbid, high‐chlorophyll waters common to the region. We developed a palustrine wetland spectral model for tracking open surface waters using Landsat imagery, which we evaluated for a 2500 km² landscape that estimates seasonal and annual open water variability for thousands of individual wetlands in the Missouri Coteau ecoregion. Detection accuracy of 96% was achieved for water bodies greater than a half‐pixel in size. We identified shifts in the distribution of water permanence classes within and between years for waters emerging in spring, mid‐summer, and late summer from 1997 to 2005 and identified a maximum of 19 047 basins with open water (12% of the landscape) populating 2500 km². For the 2005 growing season, we observed only 8757 basins with open water (6% of the landscape) for the same area. Declines were greatest for water bodies detected only in spring, suggesting a loss of those wetlands functioning to recharge groundwater stores early in the season and a high sensitivity to observed reductions in snowfall. If landscape factors driving open water coverage and wetland density are similar for the entire Missouri Coteau, we estimate the number of basins containing at least a pixel of water for this region declined from 577 600 to 266 000 between 1997 and 2005.