Allometric Inference in Morphology

SYNOPSIS. Disparate rates of change in the surfaces and volumesof organisms with change in size combine with the interdependenceof surface-limited and volume-limited functional attributesto define criteria for the size-dependency of shapes. Size contributesto the specification of types of structures required, limitsto their functional range, and the scaling relationships amongcomponents of systems. Size-dependency may be stated in termsof a null hypothesis in morphology, with departures indicativeof special adaptations which may be of particular interest.The study of size-dependency in shape and function is approachinga general theory of form with content comparable in scope toa general theory of diversity.     

A novel simple extracellular leucine-rich repeat (eLRR) domain protein from rice (OsLRR1) enters the endosomal pathway and interacts with the hypersensitive-induced reaction protein 1 (OsHIR1)

Receptor-like protein kinases (RLKs) containing an extracellular leucine-rich repeat (eLRR) domain, a transmembrane domain and a cytoplasmic kinase domain play important roles in plant disease resistance. Simple eLRR domain proteins structurally resembling the extracellular portion of the RLKs may also participate in signalling transduction and plant defence response. Yet the molecular mechanisms and subcellular localization in regulating plant disease resistance of these simple eLRR domain proteins are still largely unclear. We provided the first experimental evidence to demonstrate the subcellular localization and trafficking of a novel simple eLRR domain protein (OsLRR1) in the endosomal pathway, using both confocal and electron microscopy. Yeast two-hybrid and in vitro pull-down assays show that OsLRR1 interacts with the rice hypersensitive-induced response protein 1 (OsHIR1) which is localized on plasma membrane. The interaction between LRR1 and HIR1 homologs was shown to be highly conserved among different plant species, suggesting a close functional relationship between the two proteins. The function of OsLRR1 in plant defence response was examined by gain-of-function tests using transgenic Arabidopsis thaliana . The protective effects of OsLRR1 against bacterial pathogen infection were shown by the alleviating of disease symptoms, lowering of pathogen titres and higher expression of defence marker genes.     

Response properties of the prothoracic AN2 auditory interneurone to model calling songs in the cricket Gryllus bimaculatus

Sound processing properties for calling song (CS) models, as described for the prothoracic L3 auditory neurone in Acheta domesticus, are investigated for the homologous auditory neurone 2 (AN2) in female Gryllus bimaculatus De Geer. AN2 of G. bimaculatus responds selectively to the syllable period (SP) of models of a male CS. The selectiveness of this response parallels the selectivity of phonotaxis females perform in response to the same SPs. Both, the responses of AN2 and female behaviour show clear interindividual variability. The SP‐selective responses of AN2 result from an SP‐dependent reduction in the spiking to subsequent syllables of the model CSs, measured as the percentage decrement. This SP‐dependent response does not primarily result from inbuilt properties of the AN2 membrane. Rather, it is dependent on inhibitory input to the AN2. However, clear inhibitory postsynaptic potentials in dendritic recordings of the AN2 are not encountered. This immediate response of AN2 to CSs is followed by an increased rate of tonic firing between stimulus CSs, which is termed the prolonged response, and is dependent on the carrier frequencies that make up the male CSs. With stimulation on the contralateral side of the soma of AN2s, more than 50% of AN2s exhibit a prolonged response. However, with stimulation from the ipsilateral side of the soma, most AN2s exhibit a prolonged response. The prolonged response of AN2 at 5 kHz may be even more sensitive than the immediate response. Thus, the AN2 neurone could provide a basis for phonotaxis that is selective for both the SPs and the carrier frequencies of potentially attractive calling songs.     

The Axial Tail Musculature of Recent Crocodiles and Its Phyletic Implications

The phylogenetic position of the Ganges Gharial (Gavalis gangeticus)among the living Crocodilia is reconsidered in the light ofnew biochemical and morphological data. The anatomical datasuggest a sister group relationship between Gavialis and allother living crocodilians. In contrast the biochemical evidenceindicates a sister group relationship between Gavialis and thefalse gavial, Tomistoma schlegelii, and the rest of the livingCrocodilia. The new morphological data from the dissectionsof the caudal musculature clearly favor the phylogenetic relationshipfor Gavialis as proposed by the comparative anatomists. In thisregard the findings of this study are concordant with thoseconcerning the skull construction of the living crocodilians.     

Genetic variation and phylogenetic relationships of a pantropical species group in Polystachya (Orchidaceae)

Amplified fragment length polymorphism (AFLP) markers were used to investigate the relationships among Polystachya accessions from a group of closely related pantropical tetraploids. Before starting with the fingerprinting analyses, the polyploid accessions were first included in a phylogenetic analysis using low‐copy nuclear DNA data to establish their relationships, which confirmed that they belonged to a species group of closely related allotetraploids. Neo‐ and Palaeotropical polyploid accessions formed two hybrid clades with apparently independent origins. Sampling for the AFLP analyses included single accessions from much of the range of the genus and populations from Costa Rica (CR) and Sri Lanka (SL) to compare population structure and genetic diversity in these two areas in more detail. A splits graph of the complete AFLP data showed three major clusters corresponding to three sources of population sampling (P. concreta, SL; P. foliosa, CR; P. masayensis, CR), with individual accessions from Africa and Indian Ocean islands showing a closer relationship to P. concreta from SL than to the two CR species. Individual accessions from the Neotropics occurred in more isolated positions in the splits network, with little resolution. Some P. foliosa accessions clustered with P. masayensis, suggesting some hybridization between the two species, and this was confirmed by Bayesian structure analysis. However, the splits network, structure and analyses of molecular variance indicated a generally high level of genetic divergence between the two CR species, despite their recent hybrid origin, occurrence in largely the same localities and occasional hybridization. Polystachya foliosa from CR had a higher degree of population‐level genetic structure (Φ_ST = 0.291) than P. masayensis from CR (Φ_ST = 0.161) and P. concreta from SL (Φ_ST = 0.138), possibly because of its occurrence within a larger and more environmentally diverse continuous range than the other two species. Genetic divergence between Neo‐ and Palaeotropical members of the pantropical tetraploid group of Polystachya and the nonmonophyly of P. concreta suggested that P. concreta s.l. should be split and the use of this epithet should be confined to the Neotropics (the type is from Martinique). Other names should be used in Africa and the Asian tropics. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 165 , 235–250.     

Effects of sample size,number of markers,and allelic richness on the detection of spatial genetic pattern

The influence of study design on the ability to detect the effects of landscape pattern on gene flow is one of the most pressing methodological gaps in landscape genetic research. To investigate the effect of study design on landscape genetics inference, we used a spatially‐explicit, individual‐based program to simulate gene flow in a spatially continuous population inhabiting a landscape with gradual spatial changes in resistance to movement. We simulated a wide range of combinations of number of loci, number of alleles per locus and number of individuals sampled from the population. We assessed how these three aspects of study design influenced the statistical power to successfully identify the generating process among competing hypotheses of isolation‐by‐distance, isolation‐by‐barrier, and isolation‐by‐landscape resistance using a causal modelling approach with partial Mantel tests. We modelled the statistical power to identify the generating process as a response surface for equilibrium and non‐equilibrium conditions after introduction of isolation‐by‐landscape resistance. All three variables (loci, alleles and sampled individuals) affect the power of causal modelling, but to different degrees. Stronger partial Mantel r correlations between landscape distances and genetic distances were found when more loci were used and when loci were more variable, which makes comparisons of effect size between studies difficult. Number of individuals did not affect the accuracy through mean equilibrium partial Mantel r, but larger samples decreased the uncertainty (increasing the precision) of equilibrium partial Mantel r estimates. We conclude that amplifying more (and more variable) loci is likely to increase the power of landscape genetic inferences more than increasing number of individuals.     

Testing for a decline in diversity prior to extinction: Languedocian (latest mid‐Cambrian) distribution of cinctans (Echinodermata) in the Iberian Chains,NE Spain

Abstract: The middle Cambrian strata of the Iberian Chains (north‐eastern Spain) and the Montagne Noire (southern France) record an adaptative radiation of cinctans and trilobites, which spanned the Leonian–early Languedocian interval. A diachronous diversity peak was reached by both benthic groups when favourable palaeoenvironmental conditions (clayey vs. silty substrates) were established. The acme in diversity was followed by a gradual decline and a barren interval associated with the onset of the mid‐Languedocian regression, well constrained throughout the western Mediterranean region. For trilobites, the aftermath of the regression is characterized by a late‐Languedocian major faunal turnover of families, followed by a renewed Furongian–early Tremadocian radiation related to the stepwise immigration of trilobite invaders from northern and eastern Gondwana, under persistent transgressive conditions. In contrast, the cinctans reappeared only patchily in late‐Languedocian monospecific coquinas and finally disappeared before the Furongian. Thus, the late Languedocian is a crucial interval in which to analyse the decline in diversity and final extinction of cinctans in the aftermath of the mid‐Languedocian regression.