Alternative reproductive tactics and the propensity of hybridization

One explanation for hybridization between species is the fitness benefits it occasionally confers to the hybridizing individuals. This explanation is possible in species that have evolved alternative male reproductive tactics: individuals with inferior tactics might be more prone to hybridization provided it increases their reproductive success and fitness. Here we experimentally tested whether the propensity of hybridization in the wild depends on male reproductive tactic in Calopteryx splendens damselflies. Counter to our expectation, it was males adopting the superior reproductive tactic (territoriality) that had greatest propensity to hybridize than males adopting the inferior tactics (sneakers and floaters). Moreover, among the territorial males, the most ornamented males had greatest propensity to hybridize whereas the pattern was reversed in the sneaker males. Our results suggest that there is fluctuating selection on male mate discrimination against heterospecific females depending on both ornament size and the male’s reproductive tactic.     

Perspectives from early career researchers on the publication process in ecology – a response to Statzner & Resh (2010)

1. Two senior ecologists summarised their experience of the scientific publication process ( Statzner & Resh, Freshwater Biology, 2010 ; 55 , 2639) to generate discussion, particularly among early career researchers (ECRs). As a group of eight ECRs, we comment on the six trends they described. 2. We generally agree with most of the trends identified by Statzner & Resh (2010) , but also highlight a number of divergent perspectives and provide recommendations for change. Trends of particular concern are the use of inappropriate metrics to evaluate research quality (e.g. impact factor) and the salami slicing of papers to increase paper count. We advocate a transparent and comprehensive system for evaluating the research. 3. We stress the importance of impartiality and independence in the peer review process. We therefore suggest implementation of double‐blind review and quality control measures for reviewers and possibly editors. Besides such structural changes, editors should be confident to overrule biased reviewer recommendations, while reviewers should provide helpful reviews but be explicit if a submission does not meet quality standards. Authors should always conduct a thorough literature search and acknowledge historical scientific ideas and methods. Additionally, authors should report low‐quality copy editing and reviews to the editors. 4. Both early and late career researchers should jointly implement these recommendations to reverse the negative trends identified by Statzner & Resh (2010) . However, more senior scientists will always have to take the lead with respect to structural changes in the publication system given that they occupy the majority of decision‐making positions.     

Pathways of Proton Transfer in Cytochrome c Oxidase

During the last few years our knowledge of the structure and function of heme copper oxidases has greatly profited from the use of site-directed mutagenesis in combination with biophysical techniques. This, together with the recently-determined crystal structures of cytochrome c oxidase, has now made it possible to design experiments aimed at targeting specific pump mechanisms. Here, we summarize results from our recent kinetic studies of electron and proton-transfer reactions in wild-type and mutant forms of cytochrome c oxidase from Rhodobacter sphaeroides. These studies have made it possible to identify amino acid residues involved in proton transfer during specific reaction steps and provide a basis for discussion of mechanisms of electron and proton transfer in terminal oxidases. The results indicate that the pathway through K(I-362)/T(I-359), but not through D(I-132)/E(I-286), is used for proton transfer to a protonatable group interacting electrostatically with heme a ₃, i.e., upon reduction of the binuclear center. The pathway through D(I-132)/E(I-286) is used for uptake of pumped and substrate protons during the pumping steps during O₂ reduction.     

A high degree of aneuploidy in frozen-thawed human preimplantation embryos

We have studied the chromosomal content in 68 normally fertilised freeze-thawed human embryos of good morphology from 34 patients with an average maternal age of 32,6 years. Forty embryos showed post-thaw cellular division and twenty-eight post-thaw cleavage arrest. After spreading of the embryos on microscope slides, analysis of chromosomes X, Y, 15, 16, 17 and 18 was performed using two rounds of fluorescent in situ hybridisation (FISH). According to the results, the embryos were divided into four groups: (I) normal, all nuclei uniformly diploid, (II) diploid mosaics, normal diploid blastomeres in combination with abnormal blastomeres, (III) abnormal, all nuclei abnormal, (IV) chaotic, the chromosome constitution varies randomly from cell to cell. Approximately 25% of the embryos had normal number of the chromosomes tested, while the majority of the embryos were abnormal. Most of the abnormal embryos were diploid mosaics (57%). This was true for the embryos showing cleavage division as well as the embryos showing cleavage arrest. Our data show a slightly higher incidence of abnormal embryos compared to those obtained with FISH in non-cryopreserved embryos and confirm that the majority of preimplantation embryos fertilised in vitro contain abnormal blastomeres. The results, mechanisms, significance and implications are discussed. Received: 19 November 1998 / Accepted: 4 March 1999     

Species extinction in finite replicator systems

Species extinction in finite random replicator systems is investigated as a function of within‐species interaction pressure. Extinctions are shown to increase with increased symmetry of among‐species interactions. The proportion of extinct species increases with increased system size. The effect of system connectance is reduced to a variability effect: connectivity geometry appears unimportant as long as closed subspaces are not formed. A small system can be interpreted as a closed subsystem of a larger system, which allows size‐scaling of the interaction pressure. At large interaction pressure, the scaling unifies the proportion of extinct species. At the limit of small within‐species interaction pressure, a small number of species survive, and the proportion of extinct species shows a system size effect. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 689–697.     

Ecological adaptations of grassland‐inhabiting flightless Orthoptera: Fulvoscirtes and Acanthoscirtes,two new genera of African Karniellina (Orthoptera,Tettigoniidae, Conocephalinae,Conocephalini)

Two new genera, Fulvoscirtes n.gen. and Acanthoscirtes n.gen. , are established within the subtribe Karniellina of Conocephalini. Fulvoscirtes is based on Xiphidion kilimandjaricum Sjöstedt, 1909 and Acanthoscirtes on Phlesirtes kevani Chopard from northern Kenya. The majority of Fulvoscirtes spp. are confined to open grasslands in the submontane zone of mountains. Fulvoscirtes contains eight species, seven of which are newly described in this paper. Three species and one subspecies occur on Mt Kilimanjaro. These are F. kilimandjaricum (Sjöstedt) constricted to the southern slopes, F. legumishera n.sp. confined to the northern side and F. sylvaticus n.sp. occurring on the western side of Kilimanjaro and on the eastern slopes of Mt Meru. Fulvoscirtes fulvus n.sp. is divided into two subspecies, F. fulvus fulvus n.ssp. found in the submontane zone of east Kilimanjaro and F. fulvus parensis n.ssp. in submontane to montane localities of the North and South Pare mountains. Fulvoscirtes fulvotaitensis n.sp. occurs in the Taita Hills of southern Kenya. Fulvoscirtes viridis n.sp. is described from savannah habitats between Mts Longido and Meru. Fulvoscirtes laticercus n.sp. is found in the Kenyan highlands, while the most southerly occurring species, Fulvoscirtes manyara n.sp. , is found on Mt Hanang and the Mbulu highlands of northwestern Tanzania. Acanthoscirtes contains three species, of which A. albostriatus n.sp. is described newly from savannah habitas of eastern Kilimanjaro. Information is given on the ecology and the acoustic behaviour of some of the species together with keys to the genera of the Karniellina and the species of Fulvoscirtes and Acanthoscirtes. The genera of Karniellina probably evolved at a time when grasslands spread in East Africa due to an increasing aridification of the climate. The earliest lineage, the genus Karniella, is adapted to more forested habitats while the majority of the genera of Karniellina prefer open grasslands. Major splits within Karniellina probably occurred with the emergence of savannah grasslands due to the ongoing fragmentation of forest habitats several millions years ago, but most species within the genera are geologically young, their radiation being boosted by climatic fluctuations of the past 1–2 Ma.     

Inferring the minimum pH of streams from macroinvertebrates using weighted averaging regression and calibration

1. Data on macroinvertebrates and stream chemistry were collected from sixty-four streams in Finland. Weighted averaging (WA) regression and calibration models were constructed to infer the minimum pH of streams from their invertebrate assemblages. The purpose was to develop an instrument for biological assessment and monitoring of stream acidification. The WA method was compared with simpler approaches, based on qualitative invertebrate data and pH tolerance limits, that are widely used.
2. Performance of the two approaches was assessed in terms of correlation between the inferred and observed minimum pH within the 'training set', and in terms of root mean squared differences (predicted – observed) (RMSEP) estimated by cross-validation or bootstrap resampling techniques. The models were further tested using independent data from the literature representative of a wide geographical range.
3. The predictive power of the WA models was reasonable (RMSEP 0.40–0.44 pH units) in the training set and consistently better than that of the tolerance limit method. In contrast to the latter, the WA models were able to infer a minimum pH above 5.5, suggesting they could detect the early stages of acidification.
4. The WA models performed better than the tolerance limit method in inferring pH from the independent literature, further demonstrating the superiority and generality of the WA approach.
5. The weighted averaging technique could be an effective and widely applicable tool for contemporary biological monitoring and assessment using aquatic invertebrates.     

Evolution of seed storage protein genes: Legumin genes of Ginkgo biloba

Legumin-like seed storage proteins have been intensively studied in crop plants. However, little is known about the molecular evolution of these proteins and their genes and it was assumed that they originated from an ancestral gene that already existed at the beginning of angiosperm evolution. We have evidence for the ubiquitous occurrence of homologous proteins in gymnosperms as well. We have characterized the major seed storage globulin from Ginkgo biloba by amino acid sequencing, which reveals clear homology to legumin-like proteins from angiosperms. The Ginkgo legumin is encoded by a gene family; we describe two of its members. The promoter regions contain sequence motifs which are known to function as regulatory elements involved in seed-specific expression of angiosperm legumins, although the tissues concerned are different in gymnosperms and angiosperms. The Ginkgo legumin gene structure is divergent from that of angiosperms and suggests that the evolution of legumin genes implicated loss of introns. From our data and from functional approaches recently described it becomes obvious that the posttranslational processing site of legumin precursors is less conserved than hitherto assumed. Finally, we present a phylogenetic analysis of legumin encoding sequences and discuss their utility as molecular markers for the reconstruction of seed plant evolution.Correspondence to: K.-P. Häger