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1.
The effects of logging on three species of common skinks were estimated from censuses in four age classes of forest: unlogged, just logged, 1-year logged and 10–15 year regrowth. The effects of topography (ridge and gully) were examined in each age class. Afire in November 1980 occurred fust after the initial census was completed. Another census was taken in December 1980 to assess its immediate effects. Further censuses were carried out each December from 1981 to 1984. An intense drought overlapped from 1980 to 1983 with the census period. Lampropholis guichenoti occurred in about equal numbers in unlogged and recently logged forest, but its numbers were reduced in the 10–15 year regrowth forest. This was attributed to changes in the amount and pattern of sunlight reaching the ground. A similar pattern of response was found for Lampropholis delicata. The numbers of Eulamprus heatwolei, a gully species requiring partial shade, were lowest in the exposed, recently-logged forest, but had increased in the 10–15 year regrowth class to about equal their numbers in unlogged forest. Fire reduced the numbers ofL. guichenoti on ridges but had no immediate impact on numbers of tire other species, while drought markedly depressed numbers of all species. Lampropholis guichenoti recovered more quickly from the drought than did L. delicata, but the numbers of E. heatwolei were still declining 19 months after the drought broke. The drought also revealed a habitat (ridge/gully) difference between the two Lampropholis species. The management of these species in commercial forests requires that some areas, particularly gullies, be reserved and the logging sequence modified to prevent the creation of widespread stands of uniform regrowth. 相似文献
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Two new, closely related species of the genus Ackaeta, A. urbana sp.n. and A. microcosmi sp.n. , (Enchytraeidae, Oligochaeta) from meadow and pasture soils of Berlin and Frankfurt (Germany) are described. Both show the same form and length/width ratio of the seminal funnel and the same general shape of the spermathecal system. They are distinguishable by distributions of epidermal sacs: only dorsal (A. microcosmi) or dorsal and ventral (A. urbana) . Also the origin of the dorsal blood vessel is different. 相似文献
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Phylogenomic species delimitation and host‐symbiont coevolution in the fungus‐farming ant genus Sericomyrmex Mayr (Hymenoptera: Formicidae): ultraconserved elements (UCEs) resolve a recent radiation 下载免费PDF全文
ANA JEŠOVNIK JEFFREY SOSA‐CALVO MICHAEL W. LLOYD MICHAEL G. BRANSTETTER FERNANDO FERNÁNDEZ TED R. SCHULTZ 《Systematic Entomology》2017,42(3):523-542
Ants in the Neotropical genus Sericomyrmex Mayr cultivate fungi for food. Both ants and fungi are obligate, coevolved symbionts. The taxonomy of Sericomyrmex is problematic because the morphology of the worker caste is generally homogeneous across all of the species within the genus, species limits are vague, and the relationships between them are unknown. We used ultraconserved elements (UCEs) as genome‐scale markers to reconstruct evolutionary history and to infer species boundaries in Sericomyrmex. We recovered an average of ~990 UCE loci for 88 Sericomyrmex samples from across the geographical range of the genus as well as for five outgroup taxa. Using maximum likelihood and species‐tree approaches, we recovered nearly identical topologies across datasets with 50–95% matrix completeness. We identify nine species‐level lineages in Sericomyrmex, including two new species. This is less than the previously described 19 species, even accounting for two species for which we had no UCE samples, which brings the total number of Sericomyrmex species to 11. Divergence‐dating analyses recovered 4.3 Ma as the crown‐group age estimates for Sericomyrmex, indicating a recent, rapid radiation. We also sequenced mitochondrial cytochrome oxidase subunit I (COI) for 125 specimens. Resolution and support for clades in our COI phylogeny are weak, indicating that COI is not an appropriate species‐delimitation tool. However, taxa within species consistently cluster together, suggesting that COI is useful as a species identification (‘DNA barcoding’) tool. We also sequenced internal transcribed spacer (ITS) and large subunit (LSU) for 32 Sericomyrmex fungal cultivars. The fungal phylogeny confirms that Sericomyrmex fungi are generalized higher‐attine cultivars, interspersed with Trachymyrmex‐associated fungal species, indicating cultivar sharing and horizontal transfer between these two genera. Our results indicate that UCEs offer immense potential for delimiting and resolving relationships of problematic, recently diverged species. 相似文献
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MICHAEL KESSLER 《Botanical journal of the Linnean Society. Linnean Society of London》2008,157(2):165-167
Elaphoglossum praetrepidans M. Kessler, characterized by long-creeping rhizomes with entire rhizome scales, ill-defined phyllopodia, linear-elliptic, firmly chartaceous blades lacking hydathodes, and ovate to lanceolate, basifixed to peltate, denticulate blade scales, is described based on a single specimen from lowland Bolivia. This combination of characters suggests affinity to Elaphoglossum section Lepidoglossa , but precludes placement in any of the established subsections within that section. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 157 , 165–167. 相似文献
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Effect of soil water stress on soil respiration and its temperature sensitivity in an 18-year-old temperate Douglas-fir stand 总被引:5,自引:0,他引:5
RACHHPAL S. JASSAL T. ANDREW BLACK MICHAEL D. NOVAK DAVID GAUMONT-GUAY ZORAN NESIC 《Global Change Biology》2008,14(6):1305-1318
We analyzed 17 months (August 2005 to December 2006) of continuous measurements of soil CO2 efflux or soil respiration (RS) in an 18‐year‐old west‐coast temperate Douglas‐fir stand that experienced somewhat greater than normal summertime water deficit. For soil water content at the 4 cm depth (θ) > 0.11 m3 m?3 (corresponding to a soil water matric potential of ?2 MPa), RS was positively correlated to soil temperature at the 2 cm depth (TS). Below this value of θ, however, RS was largely decoupled from TS, and evapotranspiration, ecosystem respiration and gross primary productivity (GPP) began to decrease, dropping to about half of their maximum values when θ reached 0.07 m3 m?3. Soil water deficit substantially reduced RS sensitivity to temperature resulting in a Q10 significantly < 2. The absolute temperature sensitivity of RS (i.e. dRS/dTS) increased with θ up to 0.15 m3 m?3, above which it slowly declined. The value of dRS/dTS was nearly 0 for θ < 0.08 m3 m?3, thereby confirming that RS was largely unaffected by temperature under soil water stress conditions. Despite the possible effects of seasonality of photosynthesis, root activity and litterfall on RS, the observed decrease in its temperature sensitivity at low θ was consistent with the reduction in substrate availability due to a decrease in (a) microbial mobility, and diffusion of substrates and extracellular enzymes, and (b) the fraction of substrate that can react at high TS, which is associated with low θ. We found that an exponential (van't Hoff type) model with Q10 and R10 dependent on only θ explained 92% of the variance in half‐hourly values of RS, including the period with soil water stress conditions. We hypothesize that relating Q10 and R10 to θ not only accounted for the effects of TS on RS and its temperature sensitivity but also accounted for the seasonality of biotic (photosynthesis, root activity, and litterfall) and abiotic (soil moisture and temperature) controls and their interactions. 相似文献
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NANCY D. MONCRIEF RONALD A. VAN DEN BUSSCHE RAYMOND D. DUESER DUSTIN LOFTIS NOELLE E. COCKETT MELANIE CULVER 《The Journal of wildlife management》2008,72(1):320-323
Abstract The Delmarva fox squirrel (Sciurus niger cinereus) has been listed as endangered by the United States Department of Interior since 1967. A high-priority task for the recovery of this taxon is to determine its current geographic distribution. Toward this end, we have identified a microsatellite locus that unambiguously differentiates Delmarva fox squirrels from eastern gray squirrels (S. carolinensis), which frequently co-occur with Delmarva fox squirrels. Analysis of this marker in noninvasively collected hair samples will allow unequivocal identification of localities occupied by Delmarva fox squirrels with a minimum investment of funds, time, and effort because handling individuals will be unnecessary. This protocol will expedite site review in connection with the Endangered Species Act consultation process. 相似文献
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MECHANICS OF CILIARY LOCOMOTION 总被引:6,自引:0,他引:6
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