scholarly journals Mechanical vs. Beetle-mediated Self-pollination in Gossypium Tomentosum (Malvaceae), an Endangered Shrub

2010 ◽  
Vol 2 ◽  
pp. IJIS.S4801 ◽  
Author(s):  
Kyra N. Krakos ◽  
Gary M. Booth ◽  
Peter Bernhardt
Keyword(s):  
Field Observations ◽  
Behavioral Experiments ◽  
Self Pollination ◽  
Pollen Vector ◽  
Output Field ◽  
Insular Endemic ◽  
Gossypium Tomentosum ◽  
Regular Contact ◽  
Anthophilous Insects

Experimental hand pollinations of the endangered, Hawaiian, endemic, Gossypium tomentosum Nutt. Ex. (Malvaceae) showed that it was self-compatible, but self-pollination resulted in reduced reproductive output. Field observations and pollen tube analyses using fluorescence microscopy showed that mechanical self-pollination in this species included a mechanism known as bending stigmas. A receptive stigma bent backwards and contacted dehiscent anthers in 7% of flowers found on 17 G. tomentosum plants. The yellow flowers were nectarless and were not visited by most anthophilous insects in situ except for the introduced, nitidulid beetle, Aethina concolor Macleay. Collections and insect GI-tract dissections showed that A. concolor carried and ate the pollen of the host flower. Field observations recorded regular contact between beetles and stigma lobes as these insects exited the flowers effecting self-pollination. Behavioral experiments showed that the beetles responded positively to a yellow visual cue. Under some circumstances, an introduced pollen vector may help maintain a low level of reproductive success in an insular endemic.

scholarly journals Ages and ablation and accumulation rates from 14C measurements on Antarctic ice

1995 ◽  
Vol 21 ◽  
pp. 139-143 ◽  
Author(s):  
J.J. Van Roijen ◽  
K. van der Borg ◽  
A.F.M. De Jong ◽  
J. Oerlemans
Keyword(s):  
Mass Spectrometry ◽  
Accelerator Mass Spectrometry ◽  
Ice Cores ◽  
Extraction Technique ◽  
Field Observations ◽  
Accumulation Rates ◽  
Yield Data ◽  
Surface Ice ◽  
In Situ Production

Shallow ice cores from an Antarctic blue-ice area at Scharffenbergbotnen were l4C-analyzed using a dry-extraction technique and accelerator mass spectrometry. The in situ production was determined from the 14CO component and used to deduce the natural 14CO2 component. The ages were measured at 10 000 ± 3000 BP. The accumulation and ablation rates determined from the in situ production are 7–20 and 10 cm a−1. respectively, showing agreement with field observations. The derived ages and air-yield data show a nearby origin for the surface ice.

scholarly journals Multiscale approach reveals that Cloudina aggregates are detritus and not in situ reef constructions

2018 ◽  
Vol 115 (11) ◽  
pp. E2519-E2527 ◽  
Author(s):  
Akshay Mehra ◽  
Adam Maloof
Keyword(s):  
Imaging System ◽  
Imaging Techniques ◽  
Minor Role ◽  
Multiscale Approach ◽  
Field Observations ◽  
3D Reconstructions ◽  
Physical Separation ◽  
A Minor ◽  
Globally Distributed

The earliest metazoans capable of biomineralization appeared during the late Ediacaran Period (635–541 Ma) in strata associated with shallow water microbial reefs. It has been suggested that some Ediacaran microbial reefs were dominated (and possibly built) by an abundant and globally distributed tubular organism known as Cloudina. If true, this interpretation implies that metazoan framework reef building—a complex behavior that is responsible for some of the largest bioconstructions and most diverse environments in modern oceans—emerged much earlier than previously thought. Here, we present 3D reconstructions of Cloudina populations, produced using an automated serial grinding and imaging system coupled with a recently developed neural network image classifier. Our reconstructions show that Cloudina aggregates are composed of transported remains while detailed field observations demonstrate that the studied reef outcrops contain only detrital Cloudina buildups, suggesting that Cloudina played a minor role in Ediacaran reef systems. These techniques have wide applicability to problems that require 3D reconstructions where physical separation is impossible and a lack of density contrast precludes tomographic imaging techniques.

scholarly journals Records of two toads Duttaphrynus scaber and D. stomaticus (Amphibia: Anura: Bufonidae) from southeastern India

2020 ◽  
Vol 12 (10) ◽  
pp. 16272-16278
Author(s):  
S.R. Ganesh ◽  
M. Rameshwaran ◽  
Naveen A. Joseph ◽  
Ahamed M. Jerith ◽  
Sushil K. Dutta
Keyword(s):  
Natural History ◽  
Morphological Data ◽  
Field Observations ◽  
Coastal Plains ◽  
Voucher Specimens ◽  
Incorrect Data

We document two toad species Duttaphrynus scaber and D. stomaticus from southeastern India, in the Coromandel Coastal Plains.  Owing to incorrect data presented in previous reports denoting the occurrence of these toad species, their occurrence in the said region has remained obscure.  Our results, presented here, on both the species are based on morphological data from 15 preserved voucher specimens and direct field observations made by the authors in situ.  In this work, we report D. scaber from Chengelpet and D. stomaticus from Thoothukudi.  We revisited these places after studying the labeled specimens in Chennai Snake Park Trust Museum, to confirm their occurrences in the respective region and provide natural history notes based on our field observations.

scholarly journals Ages and ablation and accumulation rates from 14C measurements on Antarctic ice

1995 ◽  
Vol 21 ◽  
pp. 139-143 ◽  
Author(s):  
J.J. Van Roijen ◽  
K. van der Borg ◽  
A.F.M. De Jong ◽  
J. Oerlemans
Keyword(s):  
Mass Spectrometry ◽  
Accelerator Mass Spectrometry ◽  
Ice Cores ◽  
Extraction Technique ◽  
Field Observations ◽  
Accumulation Rates ◽  
Yield Data ◽  
Surface Ice ◽  
In Situ Production

Shallow ice cores from an Antarctic blue-ice area at Scharffenbergbotnen were l4C-analyzed using a dry-extraction technique and accelerator mass spectrometry. The in situ production was determined from the 14CO component and used to deduce the natural 14CO2 component. The ages were measured at 10 000 ± 3000 BP. The accumulation and ablation rates determined from the in situ production are 7–20 and 10 cm a−1. respectively, showing agreement with field observations. The derived ages and air-yield data show a nearby origin for the surface ice.

Isotopic insights into smoothening of abandoned fan surfaces, Southern California

2006 ◽  
Vol 66 (1) ◽  
pp. 109-118 ◽  
Author(s):  
Ari Matmon ◽  
Kyle Nichols ◽  
Robert Finkel
Keyword(s):  
Surface Sediments ◽  
San Andreas Fault ◽  
Field Observations ◽  
Cosmogenic Nuclide ◽  
San Andreas ◽  
The Difference ◽  
Topographic Relief ◽  
Geomorphic Processes ◽  
Over Time

AbstractCosmogenic nuclide concentrations measured on abandoned fan surfaces along the Mojave section of the San Andreas Fault suggest that sediment is generated, transported, and removed from the fans on the order of 30–40 kyr. We measured in situ produced cosmogenic 10Be, and in some cases 26Al, in boulders (n = 15), surface sediment (n = 15), and one depth profile (n = 9). Nuclide concentrations in surface sediments and boulders underestimate fan ages, suggesting that 10Be accumulation is largely controlled by the geomorphic processes that operate on the surfaces of the fans and not by their ages.Field observations, grain-size distribution, and cosmogenic nuclide data suggest that over time, boulders weather into grus and the bar sediments diffuse into the adjacent swales. As fans grow older the relief between bars and swales decreases, the sediment transport rate from bars to swales decreases, and the surface processes that erode the fan become uniform over the entire fan surface. The nuclide data therefore suggest that, over time, the difference in 10Be concentration between bars and swales increases to a maximum until the topographic relief between bars and swales is minimized, resulting in a common surface lowering rate and common 10Be concentrations across the fan. During this phase, the entire fan is lowered homogeneously at a rate of 10–15 mm kyr−1.

scholarly journals Free Ocean CO<sub>2</sub> Enrichment (FOCE) systems: present status and future developments

2014 ◽  
Vol 11 (3) ◽  
pp. 4001-4046 ◽  
Author(s):  
J.-P. Gattuso ◽  
W. Kirkwood ◽  
J.P. Barry ◽  
E. Cox ◽  
F. Gazeau ◽  
...  
Keyword(s):  
Indirect Effects ◽  
Laboratory Experiments ◽  
Experimental Approach ◽  
Co2 Enrichment ◽  
Field Observations ◽  
Biological Communities ◽  
Precise Control ◽  
Future Developments ◽  
The Impact

Abstract. Free Ocean CO2 Enrichment (FOCE) systems are designed to assess the impact of ocean acidification on biological communities in situ for extended periods of time (weeks to months). They overcome some of the drawbacks of laboratory experiments and of field observations by enabling (1) precise control of CO2 enrichment by monitoring pH as an offset of ambient pH, (2) consideration of indirect effects such as those mediated through inter-specific relationships and food-webs, and (3) relatively long experiments with intact communities. Bringing perturbation experiments from the laboratory to the field is however extremely challenging. The goal of this paper is to provide guidelines on the general design, engineering, and sensors required to conduct FOCE experiments. Present and existing FOCE systems are briefly described and examples of data collected presented. Future developments are also addressed as it is anticipated that the next generation of FOCE systems will include, in addition to pH, options for oxygen and/or temperature control. FOCE systems should become an important experimental approach for projecting the future response of marine ecosystems to environmental change.

Sign in / Sign up

Export Citation Format

Share Document