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91.
Wilson R Gradstein SR Schneider H Heinrichs J 《Molecular phylogenetics and evolution》2007,43(1):270-282
With about 1000 species in approximately 90 genera, Lejeuneaceae are the largest family of liverworts and make up a large and important part of cryptogamic diversity in the humid tropics. Maximum parsimony, Maximum likelihood and Bayesian analyses of a dataset including four markers (rbcL, psbA, trnL-trnF region of cp DNA, nrITS region) of 134 accessions resulted in similar topologies that support the presence of four main lineages within Lejeuneaceae. Model-based analyses support a division of Lejeuneaceae into two lineages corresponding to the subfamilies Ptychanthoideae and Lejeuneoideae. The latter lineage splits into the tribes Lejeuneeae, Brachiolejeuneeae and the genus Symbiezidium. In contrast, the Maximum parsimony analysis resolves Brachiolejeuneeae and Symbiezidium in serial sister relationships to the remainder of Lejeuneaceae. Sporophyte characters support a split into two subfamilies as seen in the model-based analyses. Some deep nodes remain unresolved, possibly indicating a series of initial diversifications which occurred over a short time period. 相似文献
92.
RACK1 can act as a scaffolding protein to integrate IGF-IR and integrin signalling in transformed cells but its actions in regulating IGF-IR signalling in non-transformed cells are less well understood. Here, we investigated the function of RACK1 in the non-transformed cardiomyocyte cell line H9c2. Overexpression of RACK1 in H9c2 cells was sufficient to increase cell size, increase adhesion to collagen 1, enhance protection from hydrogen peroxide-induced cell death, and increase cell migration. However, cell proliferation was decreased in these cells. Small interfering RNA (siRNA)-mediated suppression of RACK1 in H9c2 cells resulted in decreased cell adhesion and migration, but had no effect on cell proliferation or size. Increased basal and IGF-I-mediated Erk phosphorylation was observed in RACK1-overexpressing H9c2 cells. Interestingly, contrary to observations in transformed cells, RACK1 was not observed to interact with the IGF-IR in H9c2 cells. Also in contrast to observations in transformed cells, IGF-I promoted recruitment of Src to RACK1 as well as recruitment of PKC, and PKC to RACK1. Overall, the data indicate that in H9c2 cells RACK1 can influence cell size, cell survival, adhesion, migration, but its responses to IGF-I are independent of an association with the IGF-IR. Thus, the composition of the RACK1 scaffolding complex and its effects on IGF-I signalling may be different in transformed and non-transformed cells. 相似文献
93.
94.
A key issue in ecosystem management in the western U.S. is the determination of the historic range of variability of fire
and its ecological significance prior to major land-use changes associated with Euro-American settlement. The present study
relates spatial variation in historical fire occurrence to variation in abiotic and biotic predictors of fire frequency and
severity across the elevational range of ponderosa pine in northern Colorado. Logistic regression was used to relate fire
frequency to environmental predictors and to derive a probability surface for mapping purposes. These results indicate that
less than 20% of the ponderosa pine zone had an historic fire regime (pre-1915) of relatively frequent fires (mean fire intervals,
MFI, <30 years). More than 80% is reconstructed to have had a lower frequency (MFI ≥ 30 years), more variable severity fire
regime. High fire frequency is clearly associated with low elevations. Lower and more variable fire frequencies, associated
with high and moderate severities, occur across a broad range of elevation and are related to variations in other environmental
variables. Only a small part of the ponderosa pine zone fits the widespread view that the historic fire regime was characterized
mainly by frequent, low-severity that maintained open conditions. Management attempts to restore historic forest structures
and/or fire conditions must recognize that infrequent severe fires were an important component of the historic fire regime
in this cover type in northern Colorado. 相似文献
95.
Hammock Bruce G. Hartman Rosemary Dahlgren Randy A. Johnston Catherine Kurobe Tomofumi Lehman Peggy W. Lewis Levi S. Van Nieuwenhuyse Erwin Ramrez-Duarte Wilson F. Schultz Andrew A. Teh Swee J. 《Hydrobiologia》2022,849(3):675-695
Hydrobiologia - Condition indices are key predictors of health and fitness in wild fish populations. Variation in body condition, therefore, can be used to identify stressful conditions that may... 相似文献
96.
Fonseca Bárbara Medeiros Câmara Paulo Eduardo Aguiar Saraiva Ogaki Mayara Baptistucci Pinto Otávio Henrique Bezerra Lirio Juan Manuel Coria Silvia H. Vieira Rosemary Carvalho-Silva Micheline Amorim Eduardo Toledo Convey Peter Rosa Luiz Henrique 《Molecular biology reports》2022,49(1):179-188
Molecular Biology Reports - Vega Island is located off the eastern tip of the Antarctic Peninsula (Maritime Antarctica), in the Weddell Sea. In this study, we used metabarcoding to investigate... 相似文献
97.
Danny A. P. Hooftman James M. Bullock Kathryn Morley Caroline Lamb David J. Hodgson Philippa Bell Jane Thomas Rosemary S. Hails 《Annals of botany》2015,115(1):147-157
Background and Aims Gene flow from crops to their wild relatives has the potential to alter population growth rates and demography of hybrid populations, especially when a new crop has been genetically modified (GM). This study introduces a comprehensive approach to assess this potential for altered population fitness, and uses a combination of demographic data in two habitat types and mathematical (matrix) models that include crop rotations and outcrossing between parental species.Methods Full life-cycle demographic rates, including seed bank survival, of non-GM Brassica rapa × B. napus F1 hybrids and their parent species were estimated from experiments in both agricultural and semi-natural habitats. Altered fitness potential was modelled using periodic matrices including crop rotations and outcrossing between parent species.Key Results The demographic vital rates (i.e. for major stage transitions) of the hybrid population were intermediate between or lower than both parental species. The population growth rate (λ) of hybrids indicated decreases in both habitat types, and in a semi-natural habitat hybrids became extinct at two sites. Elasticity analyses indicated that seed bank survival was the greatest contributor to λ. In agricultural habitats, hybrid populations were projected to decline, but with persistence times up to 20 years. The seed bank survival rate was the main driver determining persistence. It was found that λ of the hybrids was largely determined by parental seed bank survival and subsequent replenishment of the hybrid population through outcrossing of B. rapa with B. napus.Conclusions Hybrid persistence was found to be highly dependent on the seed bank, suggesting that targeting hybrid seed survival could be an important management option in controlling hybrid persistence. For local risk mitigation, an increased focus on the wild parent is suggested. Management actions, such as control of B. rapa, could indirectly reduce hybrid populations by blocking hybrid replenishment. 相似文献
98.
Important marine habitat off east Antarctica revealed by two decades of multi‐species predator tracking
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Ben Raymond Mary‐Anne Lea Toby Patterson Virginia Andrews‐Goff Ruth Sharples Jean‐Benoît Charrassin Manuelle Cottin Louise Emmerson Nick Gales Rosemary Gales Simon D. Goldsworthy Rob Harcourt Akiko Kato Roger Kirkwood Kieran Lawton Yan Ropert‐Coudert Colin Southwell John van den Hoff Barbara Wienecke Eric J. Woehler Simon Wotherspoon Mark A. Hindell 《Ecography》2015,38(2):121-129
Satellite telemetry data are a key source of animal distribution information for marine ecosystem management and conservation activities. We used two decades of telemetry data from the East Antarctic sector of the Southern Ocean. Habitat utilization models for the spring/summer period were developed for six highly abundant, wide‐ranging meso‐ and top‐predator species: Adélie Pygoscelis adeliae and emperor Aptenodytes forsteri penguins, light‐mantled albatross Phoebetria palpebrata, Antarctic fur seals Arctocephalus gazella, southern elephant seals Mirounga leonina, and Weddell seals Leptonychotes weddellii. The regional predictions from these models were combined to identify areas utilized by multiple species, and therefore likely to be of particular ecological significance. These areas were distributed across the longitudinal breadth of the East Antarctic sector, and were characterized by proximity to breeding colonies, both on the Antarctic continent and on subantarctic islands to the north, and by sea‐ice dynamics, particularly locations of winter polynyas. These areas of important habitat were also congruent with many of the areas reported to be showing the strongest regional trends in sea ice seasonality. The results emphasize the importance of on‐shore and sea‐ice processes to Antarctic marine ecosystems. Our study provides ocean‐basin‐scale predictions of predator habitat utilization, an assessment of contemporary habitat use against which future changes can be assessed, and is of direct relevance to current conservation planning and spatial management efforts. 相似文献
99.
Raina K. Plowright Peggy Eby Peter J. Hudson Ina L. Smith David Westcott Wayne L. Bryden Deborah Middleton Peter A. Reid Rosemary A. McFarlane Gerardo Martin Gary M. Tabor Lee F. Skerratt Dale L. Anderson Gary Crameri David Quammen David Jordan Paul Freeman Lin-Fa Wang Jonathan H. Epstein Glenn A. Marsh Nina Y. Kung Hamish McCallum 《Proceedings. Biological sciences / The Royal Society》2015,282(1798)
Viruses that originate in bats may be the most notorious emerging zoonoses that spill over from wildlife into domestic animals and humans. Understanding how these infections filter through ecological systems to cause disease in humans is of profound importance to public health. Transmission of viruses from bats to humans requires a hierarchy of enabling conditions that connect the distribution of reservoir hosts, viral infection within these hosts, and exposure and susceptibility of recipient hosts. For many emerging bat viruses, spillover also requires viral shedding from bats, and survival of the virus in the environment. Focusing on Hendra virus, but also addressing Nipah virus, Ebola virus, Marburg virus and coronaviruses, we delineate this cross-species spillover dynamic from the within-host processes that drive virus excretion to land-use changes that increase interaction among species. We describe how land-use changes may affect co-occurrence and contact between bats and recipient hosts. Two hypotheses may explain temporal and spatial pulses of virus shedding in bat populations: episodic shedding from persistently infected bats or transient epidemics that occur as virus is transmitted among bat populations. Management of livestock also may affect the probability of exposure and disease. Interventions to decrease the probability of virus spillover can be implemented at multiple levels from targeting the reservoir host to managing recipient host exposure and susceptibility. 相似文献
100.
Why is Madagascar special? The extraordinarily slow evolution of pelican spiders (Araneae,Archaeidae)
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Hannah M. Wood Rosemary G. Gillespie Charles E. Griswold Peter C. Wainwright 《Evolution; international journal of organic evolution》2015,69(2):462-481
Although Madagascar is an ancient fragment of Gondwana, the majority of taxa studied thus far appear to have reached the island through dispersal from Cenozoic times. Ancient lineages may have experienced a different history compared to more recent Cenozoic arrivals, as such lineages would have encountered geoclimatic shifts over an extended time period. The motivation for this study was to unravel the signature of diversification in an ancient lineage by comparing an area known for major geoclimatic upheavals (Madagascar) versus other areas where the environment has been relatively stable. Archaeid spiders are an ancient paleoendemic group with unusual predatory behaviors and spectacular trophic morphology that likely have been on Madagascar since its isolation. We examined disparities between Madagascan archaeids and their non‐Madagascan relatives regarding timing of divergence, rates of trait evolution, and distribution patterns. Results reveal an increased rate of adaptive trait diversification in Madagascan archaeids. Furthermore, geoclimatic events in Madagascar over long periods of time may have facilitated high species richness due to montane refugia and stability, rainforest refugia, and also ecogeographic shifts, allowing for the accumulation of adaptive traits. This research suggests that time alone, coupled with more ancient geoclimatic events allowed for the different patterns in Madagascar. 相似文献