Plasticity to simulated shade is associated with altitude in structured populations of Arabidopsis thaliana

Plants compete for photosynthesis light and induce a shade avoidance syndrome (SAS) that confers an important advantage in asymmetric competition for light at high canopy densities. Shade plasticity was studied in a greenhouse experiment cultivating Arabidopsis thaliana plants from 15 populations spread across an altitudinal gradient in the northeast area of Spain that contain a high genetic variation into a reduced geographical range. Plants were exposed to sunlight or simulated shade to identify the range of shade plasticity. Fourteen vegetative, flowering and reproductive traits were measured throughout the life cycle. Shade plasticity in flowering time and dry mass was significantly associated with the altitude of population origin. Plants from coastal populations showed higher shade plasticity indexes than those from mountains. The altitudinal variation in flowering leaf plasticity adjusted negatively with average and minimum temperatures, whereas dry mass plasticity was better explained by negative regressions with the average, maximum and minimum temperatures, and by a positive regression with average precipitation of the population origin. The lack of an altitudinal gradient for the widest number of traits suggests that shade light could be a driver explaining the distribution pattern of individuals in smaller geographical scales than those explored here.     

Isolation,characterization and cross‐species amplification of microsatellite loci in the cycad genus Dioon (Zamiaceae). Potential utilization in population genetics studies of Dioon edule

Dioon edule (Zamiaceae) is an endemic Mexican cycad. Nineteen microsatellite loci were isolated from three enriched genomic libraries of D. edule var. angustifolium, D. tomasellii, and D. caputoi. Seven of these loci showed polymorphisms in D. edule. Levels of polymorphism were assessed using 16 individuals from each of seven populations throughout the range of this species. The number of alleles per locus ranged from two to five and the observed and expected heterozygosities ranged from 0.0 to 0.9821 and from 0.0088 to 0.6318, respectively. All loci show significant linkage disequilibrium. Three loci depart significantly from Hardy–Weinberg equilibrium.     

A NEW EARLY ORDOVICIAN CONODONT GENUS FROM THE SOUTHERN MONTAGNE NOIRE, FRANCE

Abstract:  Two species of a new Tremadocian (Early Ordovician) conodont genus from the Saint Chinian Formation of the southern Montagne Noire, France, are erected: Hammannodus sarae gen. et sp. nov. and Hammannodus juliae gen. et sp. nov. They were found within a single storm-induced limestone nodule interbedded with offshore shales belonging to the regional Shumardia ( C .) pusilla (trilobite) Biozone, and to the Paltodus deltifer deltifer (conodont) Subzone. This conodont record is associated with the episodic development of carbonate productivity in temperate waters of the Montagne Noire platform, a process absent in neighbouring platforms of north-west Gondwana. The apparatus is composed of five coniform pyramidal elements occupying P and S positions and one bicostate element in the M position, having three or two sharp costae, respectively, with a subtriangular basal outline.     

SERPUKHOVIAN CONODONTS FROM NORTHERN SPAIN AND THEIR BIOSTRATIGRAPHIC APPLICATION

Abstract:  Conodont collections from late Viséan–early Bashkirian deposits include numerous elements related to the cosmopolitan species Gnathodus bilineatus (Roundy) in the Cantabrian Mountains. Arnsbergian beds yield the taxa Gnathodus bilineatus leonicus subsp. nov., G. millarensis sp. nov., G. truyolsi sp. nov. and Gnathodus sp. nov. A. Almost all are also found in limestones of similar age in the Pyrenees, and the G. truyolsi conodont Zone is defined for the upper Serpukhovian of the northern Iberian Peninsula. In addition, numerous references to the proposed taxa come from Austria, Eastern Europe, Northern Africa and Asian localities. The increase in gnathodid diversity and abundance in northern Spain is related to a local Arnsbergian drowning episode of the carbonate platform. G. truyolsi is possibly derived from G. b. bilineatus , and there is morphological convergence with Gnathodus kiensis Pazukhin.     

Gene Cloning and Biochemical Characterization of an Alcohol Dehydrogenase from Euglena gracilis1

ABSTRACT. Euglena gracilis is a freshwater free‐living organism able to grow with ethanol as carbon source; to facilitate this metabolism several alcohol dehydrogenase (ADH) activities have been detected. We report the gene cloning, over‐expression, and biochemical characterization of a medium‐chain NAD⁺‐dependent ADH from E. gracilis (EgADH). The enzyme's amino acid sequence displayed the highest percentages of similarity and identity with ADHs of bacteria and fungi. In the predicted three‐dimensional model, all the residues involved in Zn²⁺, cofactor, and substrate binding were conserved. A conventional signal peptide for import into mitochondria could not be clearly identified. The protein of 37 kDa was over‐expressed, purified to homogeneity, and kinetically characterized. The enzyme's optimal pH was 7.0 for ethanol oxidation displaying a V_m of 11.7±3.6 U/mg protein and a K_m of 3.2±0.7 mM for this substrate. Isopropanol and isopentanol were also utilized, although with less efficiency. It showed specificity for NAD⁺ with a K_m value of 0.39±0.1 mM and Mg²⁺ or Zn²⁺ were essential for activity. The recombinant EgADH reported here may help to elucidate the roles that different ADHs have on the metabolism of short‐ and long‐chain alcohols in this microorganism.     

Habitat effects on resource tracking ability: do wintering Blackcaps Sylvia atricapilla track fruit availability?

If resource availability shapes population distribution, changes in resource abundance should cause parallel changes in population numbers. However, tracking ability may be disrupted by different environmental and behavioural factors that act at different spatial and temporal scales. Here we analyse the ability of wintering Blackcap Sylvia atricapilla populations to track spatio-temporal variation in fruit availability in southern Spain in two habitats (forests and shrublands) with different population structure. Former studies had shown that forests are equally used by both adult migrant and local Blackcaps, whereas shrublands are nearly monopolized by juvenile migrants. These differences might affect resource tracking: it should be disrupted in forests, as local birds remain over winter in their breeding territories, but not in shrublands where similarly competitive juvenile migrants can freely track the spatial distribution of fruits. We analysed the fruit-tracking ability of Blackcap populations among sites and years in both habitat types using a habitat-matching model, which predicts spatio-temporal changes in population abundance proportional to changes in resource availability. We counted Blackcaps and fruiting shrubs (dominated by Lentiscs Pistacia lentiscus and Wild Olives Olea europaea sylvestris ) during four winters in forest and shrubland patches. The abundance of fruits was always higher in shrublands than in forests. In shrublands, Blackcaps seemed to move freely across fruit-rich habitat patches, tracking changes in fruiting-shrub abundance among sites and years. However, such tracking was not observed in forests. This supports the view that fruit-tracking ability may be constrained by local factors, such as the social structure of populations occurring in different habitat types, which introduces spatio-temporal variation in the way fruit availability shapes the abundance distribution of these birds in their Mediterranean wintering grounds.     

Fatty acids of leaf wax esters in Coincya Rouy (Brassicaceae)

A total of 46 populations belonging to the genus Coincya Ruoy (Brassicaceae) from the Iberian Peninsula was examined for their wax ester fatty acids composition. Size of ester fatty acids in the genus Coincya varies between 14 and 28 carbon atoms. This series is dominated by acids with an even number of carbon atoms. The most abundant acids are Ojg, C^y, C^^o and C₂₆ among evens and C₁₇ and C₂₁ among odds. A positive correlation was observed between chemical composition and environmental adaptation, and also with certain morphological characters. Changes relate to low temperatures or to high relative humidity, and there is a positive correlation between chemical composition and leaf glaucousness.     

Primary growth and morphological markers of interannual growth limits in Cupressaceae from Patagonia

The present study shows experimentally that primary growth of the native Patagonian Cupressaceae Austrocedrus chilensis (D. Don) Pic.-Serm et Bizz., Fitzroya cupressoides (Molina) I. M. Johnst. and Pilgerodendron uviferum (D. Don) Florin is potentially continuous. External morphological markers of interannual growth limits have been identified for the main axes of these species after several years of observation. Such limits correspond with axis portions in which internodes are relatively short and leaves have a small distal free end forming an acute angle with the axis. The causality of these results and their utility for studying the productivity, adaptation to different environments, population management and conservation of these threatened species are discussed.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society, 2004, 146 , 285–293.     

Sex ratio, reproductive mode and genetic diversity in Triops cancriformis

1. Aquatic invertebrates display a wide array of alternative reproductive modes from apomixis to hermaphroditism and cyclical parthenogenesis. These have important effects on genetic diversity and population structure. Populations of the 'living fossil' Triops cancriformis display a range of sex ratios, and various reproductive modes are thought to underlie this variation. Using sex ratio information and histological analyses European populations have been inferred to be gonochoric (with separate males and females), selfing hermaphroditic and androdioecious, a rare reproductive mode in which selfing hermaphrodites coexist with variable proportions of males. In addition, some populations have been described as meiotic parthenogens.
2. Here we use population genetic analysis using microsatellite loci in populations with a range of sex ratios including a gonochoric population, and marker segregation patterns in heterozygote individuals reared in isolation, to clarify the reproductive mode in this species.
3. Our data show that populations in general have very low levels of genetic diversity. Non-gonochoric populations show lower genetic diversity, more heterozygote deficiencies, higher inbreeding coefficients and stronger linkage disequilibria than the gonochoric population. The maintenance of some heterozygosity in populations is consistent with some male influence in T. cancriformis populations, as would be expected from an androdioecious reproductive system. Results of marker segregation in eggs produced in isolation from non-gonochoric populations indicate that meiosis occurs and are consistent with two reproductive modes: selfing hermaphroditism and a type of ameiotic parthenogenesis.
4. Overall, our data indicate that androdioecy and selfing hermaphroditism are the most likely reproductive modes of non-gonochoric European Triops populations. Triops populations are strongly structured, suggesting high genetic drift and low levels of gene flow.     

Phylogeny of western Mediterranean Leptodirini, with an emphasis on genital characters (Coleoptera: Leiodidae: Cholevinae)

Abstract The tribe Leptodirini (Leiodidae: Cholevinae) is one of the largest radiations of Coleoptera in the subterranean environment. Although subjected to systematic and evolutionary studies, the phylogeny remains poorly understood. We assessed the phylogeny of the western Mediterranean lineages (Iberian Peninsula, Pyrenees and Sardinia) based on a cladistic analysis of fourteen characters of external morphology and twenty characters of the male and female genitalia, studied in 182 species belonging to thirty‐nine genera. We tested the monophyly of the traditional two main divisions of the group (infraflagellates and supraflagellates), as well as that of some ‘phyletic series’. The final matrix contained fifty‐eight terminal taxa, twenty‐four of which had different character state combinations. The strict consensus of the sixty most parsimonious trees recovered a monophyletic Leptodirini, but not their separation into infraflagellates and supraflagellates. The supraflagellates formed a paraphyletic group with respect to the infraflagellates (corresponding to our sampled ‘Speonomus’ series), with Notidocharis sister to all other included Leptodirini, and Speonomidius sister to Leptodirini excluding Notidocharis. The series ‘Spelaeochlamys’, including the Sardinian genera but excluding Pseudochlamys, was recovered as monophyletic with weak support. The ‘Quaestus’ series formed a polytomy with Pseudochlamys plus the ‘Speonomus’ series (including Bathysciola), which was recovered as monophyletic with strong support. Speonomus, Bathysciola, Quaestus and Troglophyes were para‐ or polyphyletic. Our results suggested the respective monophyletic origin of the Leptodirini from the Pyrenees (Pseudochlamys plus the ‘Speonomus’ series) and the Mediterranean coast plus Sardinia (series ‘Spelaeochlamys’). On the contrary, the Leptodirini of the Atlantic north coast of the Iberian Peninsula (series ‘Quaestus’ and ‘Speonomidius’) were not monophyletic.