Detarieae sensu lato (Fabaceae) from the Late Oligocene (27.23 Ma) Guang River flora of north‐western Ethiopia

New species of caesalpinioid legumes, Cynometra sensu lato and Afzelia, are described from the Late Oligocene (27.23 Ma) Guang River flora in north‐western Ethiopia. Both taxa show leaf characteristics that are shared with extant species in the Guineo‐Congolian, Sudanian and/or Zambezian regions of Africa today. The presence of these two species in Ethiopia during the Palaeogene provides further evidence of the importance of the legume tribe Detarieae in northern and north‐eastern Africa throughout much of the Cenozoic, even although the clade is poorly represented in these regions today. The fossil record documents a significant palaeogeographical and evolutionary history of Detarieae in Africa, especially compared with that of Europe and Anatolia. Based on this evidence, it is unlikely that significant diversification of extant African Detarieae took place on the Eurasian landmass. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 163 , 44–54.     

Inter‐regional comparison of land‐use effects on stream metabolism

1. Rates of whole‐system metabolism (production and respiration) are fundamental indicators of ecosystem structure and function. Although first‐order, proximal controls are well understood, assessments of the interactions between proximal controls and distal controls, such as land use and geographic region, are lacking. Thus, the influence of land use on stream metabolism across geographic regions is unknown. Further, there is limited understanding of how land use may alter variability in ecosystem metabolism across regions. 2. Stream metabolism was measured in nine streams in each of eight regions (n = 72) across the United States and Puerto Rico. In each region, three streams were selected from a range of three land uses: agriculturally influenced, urban‐influenced, and reference streams. Stream metabolism was estimated from diel changes in dissolved oxygen concentrations in each stream reach with correction for reaeration and groundwater input. 3. Gross primary production (GPP) was highest in regions with little riparian vegetation (sagebrush steppe in Wyoming, desert shrub in Arizona/New Mexico) and lowest in forested regions (North Carolina, Oregon). In contrast, ecosystem respiration (ER) varied both within and among regions. Reference streams had significantly lower rates of GPP than urban or agriculturally influenced streams. 4. GPP was positively correlated with photosynthetically active radiation and autotrophic biomass. Multiple regression models compared using Akaike’s information criterion (AIC) indicated GPP increased with water column ammonium and the fraction of the catchment in urban and reference land‐use categories. Multiple regression models also identified velocity, temperature, nitrate, ammonium, dissolved organic carbon, GPP, coarse benthic organic matter, fine benthic organic matter and the fraction of all land‐use categories in the catchment as regulators of ER. 5. Structural equation modelling indicated significant distal as well as proximal control pathways including a direct effect of land‐use on GPP as well as SRP, DIN, and PAR effects on GPP; GPP effects on autotrophic biomass, organic matter, and ER; and organic matter effects on ER. 6. Overall, consideration of the data separated by land‐use categories showed reduced inter‐regional variability in rates of metabolism, indicating that the influence of agricultural and urban land use can obscure regional differences in stream metabolism.     

Modeling Wolverine Occurrence Using Aerial Surveys of Tracks in Snow

ABSTRACT We designed a novel approach to determining extent of distribution and area of occupancy for wolverines (Gulo gulo) by using aerial surveys of tracks in snow and hierarchical spatial modeling. In 2005 we used a small, fixed-wing aircraft with pilot and one observer to search 575 of 588 survey units for wolverine tracks in approximately 60,000 km² of boreal forest in northwestern Ontario, Canada. We used sinuous flight paths to scan open areas in the forest in the 100-km² survey units. We detected tracks in 138 (24%) of the 575 sampled units. There was strong evidence of occurrence (probability of occurrence >0.80) in 30% of the 588 survey units, weak evidence of occurrence (0.50–0.80) in 12%, weak evidence of absence (0.20–0.50) in 15%, and strong evidence of absence (< 0.20) in 43%. Wolverine range comprised 59% of the study area and area of occupancy was 33,400 km². With information on probability of occurrence and core areas of occupation for wolverines in our study area, resource managers and others can examine factors that influence wolverine distribution patterns and use this information to formulate best management practices that will maintain wolverines on the landscape in the face of increasing resource development. Comparing future survey results with those of our 2005 survey will provide an objective way to assess the efficacy of management practices.     

Climate change effects on walnut pests in California

Increasing temperatures are likely to impact ectothermic pests of fruits and nuts. This paper aims to assess changes to pest pressure in California's US$0.7 billion walnut industry due to recent historic and projected future temperature changes. For two past (1950 and 2000) and 18 future climate scenarios (2041–2060 and 2080–2099; each for three General Circulation Models and three greenhouse gas emissions scenarios), 100 years of hourly temperature were generated for 205 locations. Degree‐day models were used to project mean generation numbers for codling moth (Cydia pomonella L.), navel orangeworm (Amyelois transitella Walker), two‐spotted spider mite (Tetranychus urticae Koch), and European red mite (Panonychus ulmi Koch). In the Central Valley, the number of codling moth generations predicted for degree days accumulated between April 1 and October 1 rose from 2–4 in 1950 to 3–5 among all future scenarios. Generation numbers increased from 10–18 to 14–24 for two‐spotted spider mite, from 9–14 to 14–20 for European red mite, and from 2–4 to up to 5 for navel orangeworm. Overall pest pressure can thus be expected to increase substantially. Our study did not include the possibility of higher winter survival rates, leading to higher initial pest counts in spring, or of extended pest development times in the summer, factors that are likely to exacerbate future pest pressure. On the other hand, initiation of diapause may prevent an extension of the season length for arthropods, and higher incidence of heat death in summer may constrain pest population sizes. More information on the impact of climate change on complex agroecological food webs and on the response of pests to high temperatures is needed for improving the reliability of projections.     

Mitochondrial and nuclear markers support the monophyly of Dolichopodidae and suggest a rapid origin of the subfamilies (Diptera: Empidoidea)

Abstract. The Dolichopodidae is a species‐rich dipteran group with almost 7000 described species. The monophyly of the subfamilies and their relationships remain largely unknown because the polarities of key morphological characters are unclear and molecular data are available only for 9 of the 19 proposed subfamilies. Here we test whether molecular data from two nuclear (18S, 28S) and four mitochondrial (12S, 16S, Cytb, COI) genes can resolve the higher‐level relationships within the family. Our study is based on 76 Oriental species from 12 dolichopodid subfamilies and uses eight species of Empididae and Hybotidae as outgroups. Parsimony and likelihood analyses confirm the monophyly of the Dolichopodidae, as well as the monophyly of five of the ten subfamilies represented by more than two species [Sympycninae, Sciapodinae, Dolichopodinae, Hydrophorinae (excluding tribe Aphrosylini), Neurigoninae]. There is strong support for restoring the tribe Aphrosylini as a separate subfamily Aphrosylinae. The monophyly of Medeterinae, Peloropeodinae and Diaphorinae is dependent on which tree reconstruction technique is used, how indels are coded, and whether the fast‐evolving sites are excluded. Overall, we find that our sample of Oriental species is largely compatible with the subfamily concepts that were developed for the northern temperate fauna. However, our data provide little support for relationships between the subfamilies. Branch lengths, saturation, and distance plots suggest that this is probably the result of the rapid origin of dolichopodid subfamilies over a relatively short time. We find that genera that are difficult to place into subfamilies based on morphological characters are generally also difficult to place using molecular data. We predict that a dense, balanced taxon sample and protein‐encoding nuclear genes will be needed to resolve the higher‐level relationships in the Dolichopodidae.     

Repeated unidirectional introgression towards Populus balsamifera in contact zones of exotic and native poplars

As the evolutionary significance of hybridization is largely dictated by its extent beyond the first generation, we broadly surveyed patterns of introgression across a sympatric zone of two native poplars ( Populus balsamifera , Populus deltoides ) in Quebec, Canada within which European exotic Populus nigra and its hybrids have been extensively planted since the 1800s. Single nucleotide polymorphisms (SNPs) that appeared fixed within each species were characterized by DNA-sequencing pools of pure individuals. Thirty-five of these diagnostic SNPs were employed in a high-throughput assay that genotyped 635 trees of different age classes, sampled from 15 sites with various degrees of anthropogenic disturbance. The degree of admixture within sampled trees was then assessed through Bayesian clustering of genotypes. Hybrids were present in seven of the populations, with 2.4% of all sampled trees showing spontaneous admixture. Sites with hybrids were significantly more disturbed than pure stands, while hybrids comprised both immature juveniles and trees of reproductive age. All three possible F1s were detected. Advanced-generation hybrids were consistently biased towards P. balsamifera regardless of whether hybridization had occurred with P. deltoides or P. nigra. Gene exchange between P. deltoides and P. nigra was not detected beyond the F1 generation; however, detection of a trihybrid demonstrates that even this apparent reproductive isolation does not necessarily result in an evolutionary dead end. Collectively, results demonstrate the natural fertility of hybrid poplars and suggest that introduced genes could potentially affect the genetic integrity of native trees, similar to that arising from introgression between natives.