Patchy population structure in a short-distance migrant: evidence from genetic and demographic data

Species often occur in subdivided populations as a consequence of spatial heterogeneity of the habitat. To describe the spatial organization of subpopulations, existing theory proposes three main population models: patchy population, metapopulation and isolated populations. These models differ in their predicted levels of connectivity among subpopulations, and in the risk that a subpopulation will go extinct. However, spatially discrete subpopulations are commonly considered to be organized as metapopulations, even though explicit tests of metapopulation assumptions are rare. Here, we test predictions of the three models on the basis of demographic and genetic data, a combined approach so far surprisingly little used in mobile organisms. From 2002 to 2005, we studied nine subpopulations of the wetland-restricted reed bunting ( Emberiza schoeniclus ) in the southeastern part of the Canton Zurich (Switzerland), from which local declines of this species have been reported. Here, wetlands are as small as 2.7 ha and separated through intensively used agricultural landscapes. Demographic data consisted of dispersal of colour-banded individuals among subpopulations, immigration rates and extinction-/recolonization dynamics. Genetic data were based on the distribution of genetic variability and gene flow among subpopulations derived from the analysis of nine microsatellite loci. Both demographic and genetic data revealed that the patchy population model best described the spatial organization of reed bunting subpopulations. High levels of dispersal among subpopulations, high immigration into the patchy population, and genetic admixture suggested little risk of extinction of both subpopulations and the entire patchy population. This study exemplifies the idea that spatially discrete subpopulations may be organized in ways other than a metapopulation, and hence has implications for the conservation of subpopulations and species.     

Cryobanking of viable biomaterials: implementation of new strategies for conservation purposes

Cryobanking, the freezing of biological specimens to maintain their integrity for a variety of anticipated and unanticipated uses, offers unique opportunities to advance the basic knowledge of biological systems and their evolution. Notably, cryobanking provides a crucial opportunity to support conservation efforts for endangered species. Historically, cryobanking has been developed mostly in response to human economic and medical needs — these needs must now be extended to biodiversity conservation. Reproduction technologies utilizing cryobanked gametes, embryos and somatic cells are already vital components of endangered species recovery efforts. Advances in modern biological research (e.g. stem cell research, genomics and proteomics) are already drawing heavily on cryobanked specimens, and future needs are anticipated to be immense. The challenges of developing and applying cryobanking for a broader diversity of species were addressed at an international conference held at Trier University (Germany) in June 2008. However, the magnitude of the potential benefits of cryobanking stood in stark contrast to the lack of substantial resources available for this area of strategic interest for biological science — and society at large. The meeting at Trier established a foundation for a strong global incentive to cryobank threatened species. The establishment of an Amphibian Ark cryobanking programme offers the first opportunity for global cooperation to achieve the cryobanking of the threatened species from an entire vertebrate class.     

Representing Cumulative Germination. 1. A Critical Analysis of Single-value Germination Indices

Several single-value germination indices, including Kotowski'scoefficient of velocity, Maguire's speed of germination, Czabator'sgermination value, Diavanshir and Pourbiek's germination value,Timson's cumulative germination, Lehle and Putnam's Richardsfunction index, Smith and Millett's sprouting index, and Tuckerand Wright's regression index, were evaluated to test theirability to distinguish superior from inferior germination. Allexcept Timson's cumulative germination method were essentiallyno better for ranking germination responses than data on totalgermination; Kotowski's coefficient of velocity, Smith and Millet'ssprouting index, and Lehle and Putnam's Richards function indexwere markedly inferior. Because of the ambiguity inherent inany index that combines, into a single value, data about theonset, rate and extent of germination, none of the indices couldbe recommended as a way of summarizing germination. Cumulative germination, single-value germination indices, germination index, germination     

The Effect of Growth Regulators and Cu2+ on the Activation of Amylopectin-l,6-glucosidase Activity in Pea Seedlings

No evidence could be obtained for hormonal control of amylopectin-l,6-glucosidase activity in germinating peas for the first 72 hours of germination. The embryonic axis did not stimulate the appearance of enzyme activity. The autolytic system which releases amylopectin-l,6-glucosidase activity from the particulate fraction, in which it originates, was studied in greater detail. Using Cu²⁺ ions to inhibit a proteolytic enzyme in vivo, it was shown that enzyme activation can occur in the zymogen-like granules without liberation of the enzyme into the soluble cell fraction. Activity so formed is labile. Some of the data on proteolytic enzymes in peas is discussed and an attempt made to interpret the liberation of amylopectin-l,6-glucosidase in peas on the basis of the involvement of at least two distinct proteolytic enzymes.     

Respiration and Utilization of Storage Materials in Wild and Cultivated Pea Seeds during Germination

Breakdown of storage materials, oxygen uptake, respiratory control and ADP/O ratios in the cotyledons of the garden pea P. sativum and in the wild pea P. elatius were compared. Starch and protein degradation was slower in P. elatius than in P. sativum. Embryo growth began later in the wild pea. However, in the garden pea the mitochondria were uncoupled after about 48 h of germination, while in P. elatius the ability to carry out oxidative phosphorylation was maintained for 4 days. The respiratory control ratio was higher in the wild pea at all stages of germination and a steady level of oxygen uptake was maintained in the cotyledons for at least 3 days. The findings are discussed in relation to the ecological requirements for germination in the two species.     

Oscillations of the Membrane Potential of Pulvinar Motor Cells In Situ in Relation to Leaflet Movements of Desmodium motorium

The ultradian rhythmic movement of the lateral leaflets of Desmodiummotorium is accompanied by rhythmic changes of the extra- andintracellular electrical potentials in the pulvinus, which aremeasured in situ in the pulvinus against the bathing solutionof the petiole. Extra- and intracellular potentials oscillatewith 180'b0 phase difference to each other, as shown by simultaneousmeasurements of both types of potentials in the abaxial partof the pulvinus. Light-induced changes of these potentials movein opposite directions. The in situ membrane potential of themotor cells of the pulvinus was calculated from the differencebetween the extra- and intracellular potentials. It was foundto oscillate between –136 and –36 mV, in phase withthe intracellular and inverse to the extracellular potential.The phase relationship between the leaflet movement rhythm andthe in situ membrane potential rhythm was as follows: downwardmovement is preceded and accompanied by a strong depolarization,upward movement by hyperpolarization. Our results suggest that membrane depolarization in pulvinarmotor cells of Desmodium motorium drives and controls potassiumefflux and hyperpolarization potassium influx via potassiumchannels. Key words: Desmodium pulvinus, leaf movement, pulvinar motor cells, electrical potential