Habituation to disturbance in the fiddler crab (Uca annulipes) in its natural environment

Crabs of both sexes and of various sizes were subjected to a standardized test of ten consecutive disturbances in their natural habitat. Males and females reacted alike: 53 per cent became fully habituated within less than ten disturbances, and a further 12 per cent showed slower habituation. The remainder of the test individuals showed various other patterns of reactions. Reaction pattern and efficiency of habituation are size- (or age-) dependent, and they are modifiable by social interaction and by tide-determined activity phases. The structure and species composition (with regard to ocipodid crabs only) of the Uca habitat is considered briefly, and some observations on display and ‘rapping’ or drumming behaviour are reported.     

Künstliche Zwillingsbildung bei Äpfeln durch Samenteilung

Ohne ZusammenfassungMit 5 Textabbildungen     

Fehlen von Isoxanthopterin und Nicht-Autonomie in der Bildung der roten Augenpigmente bei einer Mutante (rosy2) von Drosophila melanogaster

Ohne ZusammenfassungMit 4 TextabbildungenHerrn Professor Dr. Karl v. Frisch zum 70. Geburtstag gewidmet. — Ausgeführt mit Unterstützung der Karl-Hescheler-Stiftung.     

Phasenverschiebungen der endogenen Tagesrhythmik beiPhaseolus durch Temperatur- und Lichtintensitätsänderungen

Ohne ZusammenfassungMit 13 Textabbildungen     

A Population Genomics Study of the Arabidopsis Core Cell Cycle Genes Shows the Signature of Natural Selection

Large-scale comparison of sequence polymorphism and divergence at numerous genomic loci within and between closely related species can reveal signatures of natural selection. Here, we present a population genomics study based on direct sequencing of 61 mitotic cell cycle genes from 30 Arabidopsis thaliana accessions and comparison of the resulting data to the close relative Arabidopsis lyrata. We found that the Arabidopsis core cell cycle (CCC) machinery is not highly constrained but is subject to different modes of selection. We found patterns of purifying selection for the cyclin-dependent kinase (CDK), CDK subunit, retinoblastoma, and WEE1 gene families. Other CCC gene families often showed a mix of one or two constrained genes and relaxed purifying selection on the other genes. We found several large effect mutations in CDKB1;2 that segregate in the species. We found a strong signature of adaptive protein evolution in the Kip-related protein KRP6 and departures from equilibrium at CDKD;1 and CYCA3;3 consistent with the operation of selection in these gene regions. Our data suggest that within Arabidopsis, the genetic robustness of cell cycle–related processes is more due to functional redundancy than high selective constraint.     

Predicting potential distribution of poorly known species with small database: the case of four‐horned antelope Tetracerus quadricornis on the Indian subcontinent

Information gaps on the distribution of data deficient and rare species such as four‐horned antelope (FHA) in Nepal may impair their conservation. We aimed to empirically predict the distribution of FHA in Nepal with the help of data from the Indian subcontinent. Additionally, we wanted to identify core areas and gaps within the reported range limits and to assess the degree of isolation of known Nepalese populations from the main distribution areas in India. The tropical part of the Indian subcontinent (65°–90° eastern longitude, 5°–30° northern latitude), that is, the areas south of the Himalayan Mountains. Using MaxEnt and accounting for sampling bias, we developed predictive distribution models from environmental and topographical variables, and known presence locations of the study species in India and Nepal. We address and discuss the use of target group vs. random background. The prediction map reveals a disjunct distribution of FHA with core areas in the tropical parts of central to southern–western India. At the scale of the Indian subcontinent, suitable FHA habitat area in Nepal was small. The Indo‐Gangetic Plain isolates Nepalese from the Indian FHA populations, but the distribution area extends further south than proposed by the current IUCN map. A low to intermediate temperature seasonality as well as low precipitation during the dry and warm season contributed most to the prediction of FHA distribution. The predicted distribution maps confirm other FHA range maps but also indicate that suitable areas exist south of the known range. Results further highlight that small populations in the Nepalese Terai Arc are isolated from the Indian core distribution and therefore might be under high extinction risk.     

Generation of in silico predicted coxsackievirus B3-derived MHC class I epitopes by proteasomes

Amino Acids - Proteasomes are known to be the main suppliers of MHC class I (MHC-I) ligands. In an attempt to identify coxsackievirus B3 (CVB3)-MHC-I epitopes, a combined approach of in silico...