Cues from a common predator cause survival-linked behavioral adjustments in Mojave Desert tortoises (Gopherus agassizii)

Behavioral Ecology and Sociobiology - Adult animals of many species often behave in a cannibalistic manner when encountering conspecific offspring. Kin discrimination is critical for avoiding the...     

Isotopic composition (C & N) of the suspended particles and N uptake by phytoplankton in a shallow tropical coastal lagoon

The spatial distribution of the C/N ratios and variations in δ¹³C and δ¹⁵N of suspended particulate matter were used to characterise their source in Asia’s largest brackish water lagoon, Chilika, India. In addition, the significance of re-mineralised nutrients in the primary productivity of the shallow lagoon was also determined through quantification of the subsurface nitrogen uptake conditions at two relatively stable locations in the lagoon. The results indicated that the influence of terrestrial organic matter was the maximum in the northern sector and was relatively limited at the central and southern part of the lagoon. In situ ¹⁵N uptake experiments (daytime) under biogeochemically stable conditions revealed that the N uptake by phytoplankton ranged between 0.24 and 1.01?mM?m^?3?h^?1 during pre-monsoon and post-monsoon seasons. New production and regenerated production in the shallow lagoon was also estimated by calculating f-ratios (ratio of nitrate assimilation by phytoplankton to total nitrogenous nutrient assimilation, have been estimated), which varied from 0.52 in the post-monsoon to 0.38 in the pre-monsoon. Lowering of the f-ratio from post- to pre-monsoon indicated a dominance of mineralisation over the new production.     

Fine‐resolution conservation planning with limited climate‐change information

Climate‐change induced uncertainties in future spatial patterns of conservation‐related outcomes make it difficult to implement standard conservation‐planning paradigms. A recent study translates Markowitz's risk‐diversification strategy from finance to conservation settings, enabling conservation agents to use this diversification strategy for allocating conservation and restoration investments across space to minimize the risk associated with such uncertainty. However, this method is information intensive and requires a large number of forecasts of ecological outcomes associated with possible climate‐change scenarios for carrying out fine‐resolution conservation planning. We developed a technique for iterative, spatial portfolio analysis that can be used to allocate scarce conservation resources across a desired level of subregions in a planning landscape in the absence of a sufficient number of ecological forecasts. We applied our technique to the Prairie Pothole Region in central North America. A lack of sufficient future climate information prevented attainment of the most efficient risk‐return conservation outcomes in the Prairie Pothole Region. The difference in expected conservation returns between conservation planning with limited climate‐change information and full climate‐change information was as large as 30% for the Prairie Pothole Region even when the most efficient iterative approach was used. However, our iterative approach allowed finer resolution portfolio allocation with limited climate‐change forecasts such that the best possible risk‐return combinations were obtained. With our most efficient iterative approach, the expected loss in conservation outcomes owing to limited climate‐change information could be reduced by 17% relative to other iterative approaches.     

Biogeography of soil nematodes

Biogeography is the study of distributions of organisms, plus an attempt to explain the distributions. Two approaches to explanation of biogeographic patterns may be termed ecological biogeography and historical biogeography. Most nematologists have taken the ecological approach, with a goal of determining why a particular species is restricted to certain areas, and not present in nearby areas. Historical biogeography is based on the premise that present-day patterns of taxa result largely from the history of the taxa and of the areas of the earth in which they have lived. Nematologists generally adhere to the classic view of dispersal in which a center of origin is postulated and long-range dispersal over barriers is invoked. The dispersal mechanism is often assumed to be man himself. Challenges to this approach exist in the form of methods which infer the biogeographic history from phylogeny. Vicariance biogeographers postulate fragmentation of widespread ancestral biotas, resulting from geological, climatic or other disjunctions, and further allopatric speciation among descendant biotas. Distributions amenable to general explanation can be distinguished from those which require unique dispersal events. Biogeography of soil nematodes is hampered by present limitations in systematics, including our inability to determine species limits with certainty.     

The selection of management strategies for controlling nematodes in cereals

Several genera and species of plant-parasitic nematodes cause losses in grain yield in cereals; some are of relatively minor importance (e.g. Anguina tritici (Steinbuch) Chitwood, the cause of “ear cockle” in wheat), while others such as the cereal cyst nematode (CCN) (Heterodera avenae Woll.) have a wide geographic distribution, infest extensive areas, and may cause losses valued at millions of dollars. Some of these nematodes are difficult to control because the measures that might be used are uneconomic to apply or are impractical. The control of CCN, however, can be achieved, and several successful strategies have been developed in parts of Europe and in Australia. The various measures available to Australian cereal growers include: crop rotation, resistant cultivars, manipulation of sowing dates, use of nematicides, and reduced cultivation. The selection of an appropriate management strategy for the control of CCN is influenced by factors such as: climate, cereal species grown, yield potential, rotations practised and the availability of alternative crops, pathotype present, farm size, availability of resistant cultivars, nematicides registered, and the availability of suitable equipment for their application.     

Prenatal diagnosis of campomelic dysplasia by ultrasonography

Consanguineous partners had a boy with campomelic dysplasia who died of increasing respiratory distress soon after birth. The next pregnancy was monitored frequently by ultrasonography and a healthy male infant was born at term. During a further pregnancy, ultrasonography suggested campomelic dysplasia in the 16th week of gestation. This was confirmed in the 18th week. The pregnancy was terminated and the fetus showed the typical radiological, anatomical and histological findings.     

Prenatal pleural effusion associated with congenital pulmonary lymphangiectasia

A pleural effusion associated with congenital pulmonary lymphangiectasia was detected in a fetus in utero but was absent at the time of delivery. The pleural effusion was unilateral although the disease involved both lungs. In this case there was an association between polyhydramnios and congenital pulmonary lymphangiectasia.     

The cerebro-hepato-renal (Zellweger) syndrome: Prenatal detection based on impaired biosynthesis of plasmalogens

Prenatal diagnosis of the cerebro-hepato-renal (Zellweger) syndrome has been performed in 10 pregnancies at risk by measuring both the activity of acyl CoA: dihydroxyacetonephosphate acyltransferase (DHAP-AT) and the de novo plasmalogen biosynthesis, either in cultured amniotic fluid cells or in fibroblasts cultured from a chorionic villus biopsy. In 7 of the pregnancies both tests indicated no abnormality. All 7 continued to term and normal infants were delivered. However, in amniotic fluid cells from 2 fetuses affected by Zellweger syndrome unequivocal differences from control values were found. The activity of DHAP-AT was clearly deficient and the de novo plasmalogen biosynthesis was impaired. In one pregnancy at risk prenatal diagnosis was performed during the first trimester by measuring both the DHAP-AT activity and the de novo plasmalogen biosynthesis in fibroblasts cultured from a chorionic villi biopsy. From the deficient DHAP-AT activity and the impaired de novo plasmalogen biosynthesis it was concluded that the fetus was affected. This was confirmed biochemically after induced abortion. It can be concluded that measurement of the DHAP-AT activity and the de novo plasmalogen biosynthesis provides convenient methods for the early prenatal detection of Zellweger syndrome.