Genetic variation in natural populations of Anthurium sinuatum and A. pentaphyllum var. pentaphyllum (Araceae) from north‐east Brazil using AFLP molecular markers

Genetic variation was investigated using AFLP markers in 12 populations of Anthurium sinuatum and A. pentaphyllum var. pentaphyllum (Araceae) in north‐east Brazil, Amazonia and the Brazilian Atlantic forest. Two unique genetic patterns characterized the populations of A. sinuatum as a group, but no correlation between genetic and geographical interpopulation distance was found; the Amazonian population was not separated from that in Ceará. The isolated Ceará brejo populations of A. sinuatum were genetically distinct, but genetic diversity levels were similar to populations elsewhere, with no evidence of genetic erosion. Anthurium pentaphyllum populations were significantly different from each other; Bayesian genetic structural analysis found no common genetic pattern, but revealed genetic clusters unique to subgroups and individual populations in the Atlantic forest and French Guiana. Anthurium pentaphyllum and A. sinuatum can be distinguished genetically, but individuals of both species formed intermediate genetic clusters that blurred their distinction. We suggest that genetic mixing of A. sinuatum and A. pentaphyllum has occurred in north‐east Brazil, possibly connected with cycles of humid forest expansion. The weak genetic structure in A. sinuatum is consistent with the natural fragmentation of continuous forest areas, possibly during the Holocene. This study highlights the scientific importance of the highly threatened brejo forests for tropical American biogeography. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159 , 88–105.     

Nitrogen deposition causes widespread loss of species richness in British habitats

We use national scale data to test the hypothesis that nitrogen (N) deposition is strongly negatively correlated with plant species richness in a wide range of ecosystem types. Vegetation plots from a national ecological surveillance programme were drawn from heathland, acid, calcareous and mesotrophic grassland habitats. Mean species number and mean plant traits were calculated for each plot and related to atmospheric N deposition. There was a significant reduction in species richness with N deposition in acid grassland and heathland even after fitting covarying factors. In acid grassland and heathland, evidence from trait changes suggested that acidification rather than increased fertility was responsible for species loss. In contrast, calcareous grassland showed evidence of eutrophication in response to increasing N deposition. Loss of species richness from chronic N deposition is apparent in infertile grasslands and heathland. Mechanisms associated with loss of species richness differ between habitats so mitigation of N deposition should be targeted to habitat type.     

WALKING AND JUMPING WITH PALAEOZOIC APTERYGOTE INSECTS

Abstract: Abundant arthropod walking and jumping traces, from the Lower Permian Robledo Mountains Formation of southern New Mexico, provide direct evidence of the locomotory techniques of monurans, an extinct group of archaeognathan apterygote insects. The jumping behaviour of monurans is compared with that of the extant machilid archaeognathan Petrobius. The jumping traces are referred to Tonganoxichnus robledoensis, and demonstrate that monurans were capable of forward progression via a linear succession of jumps of several times their body length. Petrobius also employs an unusual, fast, in‐phase, jumping gait for normal directed locomotion; however, unlike the T. robledoensis traces, these jumps are only about one body length. In‐phase trackways, referred to Stiaria intermedia from the Upper Carboniferous Tonganoxie Sandstone of Kansas, are found in association with Tonganoxichnus traces, indicating that monurans were also capable of such a fast jumping gait. Petrobius employs an escape jump that is more similar in terms of magnitude to those represented by T. robledoensis; however, the escape jump is essentially random in terms of direction and rotation of the body. Out‐of‐phase trackways from the Robledo Mountains Formation, also referred to Stiaria intermedia, are found preceding or following on from several Tonganoxichnus traces, and demonstrate that monurans also used normal, out‐of‐phase, walking gaits across open ground. Analysis of these trackways demonstrates that they used a variety of gaits ranging from very slow and stable gait ratios of 1·2 : 8·8 (i.e. the propulsive backstroke phase comprises 88 per cent of the step cycle) following jumps, to fast gait ratios of 3·3 : 6·7 and 5·0 : 5·0 preceding jumps. Petrobius tends not to use such normal walking gaits unless on the undersurface of rocks, preferring to use the unusual, fast, in‐phase, jumping gait over open ground. Monurans appear to have been capable of many of the same jumping behaviours as Petrobius, apart from the random escape jump. Archaeognathans are the most primitive group of true insects, and the presence of these similar types of jumping behaviours in monurans and machilids suggests that such behaviours were a primitive method of insect locomotion.     

The effects of foliage damage on casebearing moth larvae, Coleophora serratella, feeding on birch

ABSTRACT.

• 1 Mechanical damage to birch (Betula pendula Roth) leaves leads to an increase in the concentration of phenolic compounds, which spreads throughout the leaf within 8 days.
• 2 Coleophora serratella L. (Lepidoptera: Coleophoridae) apparently responds to this chemical change over a similar time scale. Within 24 h of pin-pricking leaves the casebearer moves from the immediate vicinity of the damage, but is just as likely to move to an undamaged portion of the damaged leaf as to vacate the leaf entirely. After 8 days mines on undamaged portions of damaged leaves were significantly smaller than mines on undamaged leaves.
• 3 Furthermore, Coleophora serratella reared on damaged trees took an average of 3 days longer to develop than those reared on undamaged trees.
• 4 It has been suggested that increased movement in response to damage-induced chemical changes causes hyperdispersed damage on plant foliage. Both within and between-leaf casebearer damage patterns were shown to be aggregated on birch.
• 5 Thus although mechanical damage can induce chemical and behavioural changes in the field, these are not reflected in the observed damaged patterns. We speculate on several possible reasons for this.

     

Dissociation of Lipid Components and Reconstitution at – 75° C of Mg<Superscript>2+</Superscript> Dependent,Na<Superscript>+</Superscript> and K<Superscript>+</Superscript> Stimulated,Adenosine Triphosphatase in Rat Brain

MEMBRANE enzymes, because of their lipid content, are insoluble in water and usually solubilized as micelles in aqueous solution by detergents for biochemical study. Direct study of lipid components by means of organic liquids in which they dissolve leads at once to the denaturation of the enzyme. At temperatures appreciably colder than 0° C, however, organic solvents may leave enzymatic activity intact^1–3, making it possible to study enzyme reactions.     

Interferon Induction: DNA–RNA Hybrid or Double Stranded RNA?

Interferon inducing capacity resides solely with double stranded RNA.     

The Unique Position of the Degenerating Macronucleus in Tetrahymena tropicalis1

In contrast to the situation in 13 other species of the Tetrahymena pyriformis complex, in which the condensed degenerating old macronucleus lies in the posterior end of the cell during the late stages of conjugation, in Tetrahymena tropicalis that nucleus is found in the anterior portion. This developmental characteristic may be useful for taxonomic purposes as well as being of value in investigations on nucleocytoplasmic interaction.     

Late Pleistocene and Holocene equid remains from Israel

Equid remains–mostly isolated teeth–from archaeological sites in Israel are described. Particular attention is paid to dental enamel fold morphology and criteria are established tor separating several Old World Quaternary equid species. Eauus hydruntinus , which is here considered a zebra rather than an ass, was present until 12,000 bp in northern Israel, while at the same time E-asinus/hemionus inhabited the arid regions in the south. Inirequent remains of E. caballus are also described. By 4000 years ago ass, probably the domestic form, was present in northern Israel.     

Genetic variation in natural populations of the aphid Rhopalosiphum padi as revealed by maternally inherited markers

A survey on 148 clones of the aphid Rhopalosiphum padi from 11 widespread localities has been carried out to study the genetic structure of populations of this species as revealed by mitochondrial DNA restriction site and length polymorphisms as well as by restriction site analysis of a maternally inherited plasmid carried by the aphid eubacterial endosymbiont Buchnera aphidicola. Our results support the existence in the area under study of two main aphid maternal lineages strikingly coincidental with the two main reproductive categories displayed by this species. Those aphid clones possessing an incomplete life cycle that lacks the sexual phase (anholocyclic or androcyclic clones) show mitochondrial DNA (mtDNA) haplotype I and plasmid haplotype I, whereas those clones displaying the complete life cycle (holocyclic clones) posses some other distinct mtDNA haplotypes closely related to each other and plasmid haplotype II. While restriction-site analysis of maternally inherited markers points to a relatively ancient origin of anholocycly/androcycly (between 460 000 and 1 400 000 years) followed by interrupted gene flow with respect to the ancestral holocyclic population, mtDNA size variation also suggests that historical stochastic processes have a different effect on the evolution of both main aphid lineages. Evidence of occasional nuclear gene flow between lineages and its consequences on the correspondence between maternally inherited haplotypes and life cycle are also presented and discussed.