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1.
Background
Introductions of non-native tiger salamanders into the range of California tiger salamanders have provided a rare opportunity to study the early stages of secondary contact and hybridization. We produced first- and second-generation hybrid salamanders in the lab and measured viability among these early-generation hybrid crosses to determine the strength of the initial barrier to gene exchange. We also created contemporary-generation hybrids in the lab and evaluated the extent to which selection has affected fitness over approximately 20 generations of admixture. Additionally, we examined the inheritance of quantitative phenotypic variation to better understand how evolution has progressed since secondary contact. 相似文献2.
3.
Does maternal condition or predation risk influence small mammal population dynamics? 总被引:2,自引:0,他引:2
There is strong debate over whether the intrinsic traits of individuals or the extrinsic environment exert the greater influence on small mammal population dynamics. We test the roles of maternal effects (an intrinsic factor) and predation risk (an extrinsic factor) in the population dynamics of wild strain house mice using a 2-factor enclosure experiment. Pre-release supplemental feeding with a high-fat diet created female treatment founders that were 6–10% heavier than controls, a condition that we predicted would be passed on as a maternal effect. Predation risk was enhanced using regular application of predator (red fox Vulpes vulpes ) scats. Founder populations of six females and six males released into eight, 15×15 m enclosures showed near exponential population growth over 17 weeks (maximum 3 generations). But there were no responses to either treatment in terms of survival, inherited body weights, fecundity or population size. We suggest that elevated maternal condition may have only minor and transient intergenerational effects with little long-term consequence. We also suggest that the general significance of predator scats as a cue to predation risk to alter prey behaviour may have been overestimated. Hence our results question the role of either factor in causing long-term responses that influence condition to affect population processes. 相似文献
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Household‐level correlates of children's physical activity levels in and across 12 countries 下载免费PDF全文
Deirdre M. Harrington Fiona Gillison Stephanie T. Broyles Jean‐Philippe Chaput Mikael Fogelholm Gang Hu Rebecca Kuriyan Anura Kurpad Allana G. LeBlanc Carol Maher Jose Maia Victor Matsudo Timothy Olds Vincent Onywera Olga L. Sarmiento Martyn Standage Mark S. Tremblay Catrine Tudor‐Locke Pei Zhao Peter T. Katzmarzyk for the ISCOLE Research Group 《Obesity (Silver Spring, Md.)》2016,24(10):2150-2157
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Christina M. Giovas Michelle J. LeFebvre Scott M. Fitzpatrick 《Journal of Biogeography》2012,39(3):476-487
Aim This paper investigates the prehistoric introduction of five mammalian taxa to Carriacou (Lesser Antilles) and refines the known anthropogenic ranges for these fauna in the pre‐Columbian West Indies. The importance of such records for understanding the region’s historical biogeography and ecology is considered. Location Carriacou Island, Grenada (12°28′ N, 61°26′ W). Methods Zooarchaeological assemblages from Carriacou’s earliest documented prehistoric sites, Grand Bay and Sabazan, were analysed, and exotic taxa were identified and quantified. The timing of introductions was established based on multiple radiocarbon assays, including three new accelerator mass spectrometry (AMS) direct dates obtained on the bone of exotic taxa. Source species and location(s) are considered and compared with known prehistoric records for the Caribbean to synthesize anthropogenic distributions for the pre‐Columbian period. The contexts of the zooarchaeological remains are evaluated to better understand the nature and purpose of introductions. Results Zooarchaeological investigation on Carriacou reveals the occurrence of multiple mammal introductions from South American between c. ad 700 and ad 1400. This paper presents the first records for guinea pig (Cavia sp.), armadillo (Dasypus sp.), peccary (Tayassu/Pecari sp.), opossum (Didelphis sp.) and agouti (Dasyprocta sp.) from the island. Human‐mediated transport of these taxa is indicated by their absence from the record prior to human settlement of Carriacou. Several translocated species are either rare or entirely unknown for the region, and overall West Indian distributions are temporally and spatially discontinuous. Archaeological contexts indicate that mammalian introductions arose from human subsistence needs, but other social factors may have shaped the dispersal of these fauna. Main conclusions The taxonomic combination and richness of Carriacou’s introduced fauna are unusual within the region. Importantly, the new records significantly improve the known pre‐Columbian geographic range for peccary, guinea pig and armadillo. Integrated with regional records, these data augment our understanding of the Caribbean’s historical biogeography, and have the potential to improve our understanding of human mobility and anthropogenic environmental impacts in the West Indies prior to the arrival of Europeans. 相似文献
8.
There are too many kinds of organisms to be able to study and manage each, yet the loss of a single species can sometimes unravel an ecosystem. Such `fusewire species'– critical in the same sense that an electrical fuse can cut out a whole circuit – would be a rewarding focus for research and management effort. However, this approach can only be effective if these `fusewires' represent but a small proportion of the number of species in the system.
To demonstrate methods for measuring what proportion of the species in a system are critical to ecosystem function.
The prevalence of fusewire species was measured in manipulative experiments on an aquatic microcosm.
No single genus deletion caused changes in key characteristics of the system.
Comparison of these results with other published studies shows that the proportion of critical fusewire species varies amongst different ecosystems. The oxidation pond microcosms were shown to contain no single species indispensable to system function. They appear to be ill-suited to a management strategy which focuses on priority eukaryote species. However, a single study provides no evidence that this result is general or even typical of other kinds of ecosystems; it is presented here as an empirical model. Other methods of investigation are available; they are less experimentally rigorous but more practical. These could provide important guidance in planning an approach to management in a particular ecosystem. 相似文献
Aim
To demonstrate methods for measuring what proportion of the species in a system are critical to ecosystem function.
Methods
The prevalence of fusewire species was measured in manipulative experiments on an aquatic microcosm.
Results
No single genus deletion caused changes in key characteristics of the system.
Main conclusions
Comparison of these results with other published studies shows that the proportion of critical fusewire species varies amongst different ecosystems. The oxidation pond microcosms were shown to contain no single species indispensable to system function. They appear to be ill-suited to a management strategy which focuses on priority eukaryote species. However, a single study provides no evidence that this result is general or even typical of other kinds of ecosystems; it is presented here as an empirical model. Other methods of investigation are available; they are less experimentally rigorous but more practical. These could provide important guidance in planning an approach to management in a particular ecosystem. 相似文献
9.
In this note we outline some recent results on the development of a statistical testing methodology for inverse problems involving partial differential equation models. Applications to several problems from biology are presented. The statistical tests, which are in the spirit of analysis of variance (ANOVA), are based on asymptotic distributional results for estimators and residuals in a least squares approach.Research supported in part under grants NSF MCS 8504316, NASA NAG-1-517, and AFOSRF-49620-86-C-0111. Part of this research was carried out while the first author was a visiting scientist at the Institute for Computer Applications in Science and Engineering (ICASE), NASA Langley Research Center, Hampton, VA, which is operated under NASA contracts NASI-18107 and NASI-18605 相似文献
10.
E M Cornford A M Fitzpatrick T L Quirk C P Diep E M Landaw 《The Journal of parasitology》1988,74(1):116-128
Tegumental hexose transporters have been kinetically characterized in mated and separated male and female Schistosoma mansoni 8-12 wk postinfection. Significant gender-specific differences in Km and Vmax were observed. In mated males, the estimated constants (mean +/- SE) were: Km = 0.63 +/- 0.31 mM, Vmax = 0.93 +/- 0.44 nmol/mg worm water/min, and the Kd = 0.25 +/- 0.09 microliter/mg worm water/min. In mated females the kinetics were: Km = 0.99 +/- 0.40 mM, Vmax = 1.22 +/- 0.42 nmol/mg worm water/min, and Kd = 0.60 +/- 0.14 microliter/mg worm water/min. The influx of 2-deoxy-D-glucose and 3-O-methylglucose has been similarly characterized; these analogs share the same glucose transporter in male and female schistosomes. 2-Deoxy-D-glucose has a higher affinity, and 3-O-methylglucose a lower affinity, than does glucose. Because mated male schistosomes supply glucose to female partners, similarities between the free glucose concentration of the male and the affinity of the transporter determined for mated female schistosomes suggest that male-to-female transfer may be a potentially rate-limiting step in glucose utilization by the female. Permeability x surface are (PS) products and Vmax/Km ratios were significantly elevated in mated schistosomes, suggesting that the transporter is primarily localized to the dorsal surface of the male. Gender- and mating-specific analyses of PS products indicate that tegumental permeability to glucose is significantly increased in mated schistosomes, and compares very favorably to that of the host liver. 相似文献