Karyotype differentiation in Chromaphyosemion killifishes (Cyprinodontiformes, Nothobranchiidae): patterns, mechanisms, and evolutionary implications

Chromaphyosemion killifishes are a karyotypically highly diverse group of small, sexually dimorphic fishes living in rainforest rivulets in tropical West and Central Africa. In the present study, we used various chromosome banding and staining techniques to analyse the karyotypes of 13 populations representing seven described species ( Chromaphyosemion loennbergii , Chromaphyosemion punctulatum , Chromaphyosemion splendopleure , Chromaphyosemion volcanum , Chromaphyosemion malumbresi , Chromaphyosemion melanogaster , Chromaphyosemion bitaeniatum ) and two undescribed forms ( Chromaphyosemion cf. lugens , Chromaphyosemion sp. Rio Muni GEMHS00/41). Diploid chromosome numbers (2 n ) and the number of chromosome arms (NF) ranged from 2 n  = 24 in C. malumbresi to 2 n  = 40 in C. bitaeniatum and from NF = 40 in C. volcanum and C. cf. lugens to NF = 54 in one population of C. loennbergii . A tentative XX/XY sex chromosome system was revealed in C. loennbergii , C. melanogaster , C. malumbresi , and Chromaphyosemion sp. Rio Muni GEMHS00/41. Mapping cytogenetic data for all described Chromaphyosemion species onto a recently published mitochondrial DNA phylogeny revealed a complex pattern of chromosomal evolution with several independent reductions of 2 n and independent modifications of NF and nucleolus organizer region phenotypes. Together with the results of preliminary crossing and mate choice experiments, the cytogenetic and molecular phylogenetic data suggest that, contrary to previous hypotheses, chromosomal rearrangements are probably not the most important and certainly not the only factor driving speciation in Chromaphyosemion killifishes.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 143–153.     

MIDDLE LLANDOVERY (AERONIAN) GRAPTOLITES OF THE WESTERN MURZUQ BASIN AND AL QARQAF ARCH REGION, SOUTH-WEST LIBYA

Abstract:  The taxonomy and biostratigraphy of the Aeronian graptoloid graptolites of the Tanezzuft Formation (Murzuq Basin and Al Qarqaf Arch area) is presented and discussed with respect to their palaeoenvironmental setting and palaeobiogeographical links. The gregarius-libycus , ' leptotheca ', convolutus and sedgwickii assemblage biozones and tenuis Subzone are recognized and correlated with the generalized zonal scheme and with graptoloid successions in peri-Gondwanan Europe. The Rhuddanian/Aeronian boundary is tentatively placed at the base of the gregarius-libycus Biozone. Telychian faunas have not been identified. Fourteen of the 23 species recorded herein belong to the middle Aeronian convolutus Biozone assemblage. The overall low diversity may be the result of inhabiting unstable, occasionally turbulent and/or oxic environments. The lowest diversity, but with abundant graptoloid rhabdosomes, is observed in proximal silty and sandy deposits. The presence of ' Paraclimacograptus' libycus suggests biogeographical links to Aeronian graptolite faunas of Jordan and South America. The convolutus Zone assemblage is very similar to the coeval faunas of the Saudi Arabian Qusayba shales. The occurrence of several species endemic to northern and north-western Gondwana and peri-Gondwana provides further evidence for a distinct palaeoclimatic/palaeolatitudinal control on graptolite distribution.     

Geographical patterns of hoverfly (Diptera,Syrphidae) functional groups in Europe: inconsistency in environmental correlates and latitudinal trends

Abstract 1. Relationships between species richness in higher taxa and large‐scale environmental variables have been widely studied over the past 15 years. Much less is known about how different functional groups (FGs) of species with similar biological and life‐history traits contribute to the overall trends, or how they differ in species‐richness patterns. 2. Multivariate analysis clustered 641 species of Syrphidae into eight FGs on the basis of 10 life‐history features, revealing feeding strategy as the main factor separating the groups. 3. Geographical trends in species richness and determinants of species richness within the FGs were compared across Europe. 4. Total species richness showed no latitudinal trend. However, the richness of individual FGs revealed variable relationships with latitude, including positive, negative, and hump‐shaped ones. This appeared to be related to how different environmental factors affected species richness within FGs. 5. Functional groups differed in their responses to the environmental variables. Annual temperature, evapotranspiration, and elevation span were the most important variables separating the FGs in ordination analysis. The multiple regression models showed further differences between FGs and their responses to the environment. 6. The FG approach revealed important inconsistencies in latitudinal diversity gradients and diversity‐climate relationships.     

Ultraviolet and green parts of the colour spectrum affect egg rejection in the song thrush (Turdus philomelos)

Much attention has been devoted to understanding the evolution of egg mimicry in avian brood parasites. The majority of studies have been based on human perception when scoring the mimicry of the parasitic egg. Surprisingly, there has been no detailed study on the recognition and sensitivity towards differently coloured parasitic eggs. We investigated effect of different colours of the experimental eggs measured by ultraviolet (UV)-visible reflectance spectrophotometry on rejection behaviour in the song thrush ( Turdus philomelos ). We carried out a set of experiments with four blue model eggs representing mimetic eggs, whereas six other colours represented nonmimetic eggs. Our results revealed that two colours originally designed as a mimetic were rejected at a high rate, whereas one group of the nonmimetic was accepted. A multiple regression model of absolute differences between song thrush and experimental eggs on rejection rate showed that the level of mimicry in the UV and green parts of the colour spectrum significantly influenced egg rejection in the song thrush. To our knowledge, this is the first detailed study showing that different colour perception by the birds can affect their responses towards the parasitic egg. These findings suggest that the combination of UV and visible ranges of the spectra plays a major role in the evolution of discrimination processes, as well as in the evolution of the mimicry of the parasitic egg.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 92 , 269–276.     

Phylogeography of the greater horseshoe bat, Rhinolophus ferrumequinum: contrasting results from mitochondrial and microsatellite data

Phylogeographical studies are typically based on haplotype data, occasionally on nuclear markers such as microsatellites, but rarely combine both. This is unfortunate because the use of markers with contrasting modes of inheritance and rates of evolution might provide a more accurate and comprehensive understanding of a species' history. Here we present a detailed study of the phylogeography of the greater horseshoe bat, Rhinolophus ferrumequinum , using 1098 bp of the mitochondrial ND2 gene from 45 localities from across its Palaearctic range to infer population history. In addition, we re-analysed a large microsatellite data set available for this species and compared the results of both markers to infer population relationships and the historical processes influencing them. We show that mtDNA, the most popular marker in phylogeography studies, yielded a misleading result, and would have led us to conclude erroneously that a single expansion had taken place in Europe. Only by combining the mitochondrial and microsatellite data sets are we able to reconstruct the species' history and show two colonization events in Europe, one before the Last Glacial Maximum (LGM) and one after it. Combining markers also revealed the importance of Asia Minor as an ancient refugium for this species and a source population for the expansion of the greater horseshoe bat into Europe before the LGM.     

Does plant height determine the freezing resistance in the páramo plants?

Neotropical ecosystems between treeline and snowline, called páramos, stretch along Andean ranges from Costa Rica to northern Peru. The páramo climate is characterized by regular night frosts occurring throughout the year. Páramo plants use two strategies to deal with freezing temperatures. They either avoid ice formation in the tissues or tolerate extracellular ice formation. We tested the microclimate hypothesis, which suggests that the freezing resistance of the páramo plants is determined by plant height, that is, that taller plants experience a milder microclimate and avoid freezing, whereas smaller plants are exposed to the more extreme thermal conditions near the ground and tolerate them. We measured the temperature at which ice formed inside the plants (the ‘exotherm’), and compared it with the temperature at which 50% damage to the tissue occurred (Lt50); a significant difference between the exotherm and Lt50 would indicate freezing tolerance whereas the absence of a difference would indicate avoidance by supercooling. We analysed the freezing resistance of 38 common Ecuadorian páramo species. We found no correlation between plant height and freezing resistance mechanism or injury temperature and reject the microclimate hypothesis. Tolerant plants reach higher altitudes than avoidant plants, but their altitudinal ranges largely overlap and the Lt50 does not differ between them. These results suggest that there is no qualitative difference between the two strategies to survive the páramo frosts. Shrub leaves were injured at significantly lower temperatures than other life forms, such as herbs, which may reflect leaf anatomical differences among the plants.     

Larval morphology enhances phylogenetic reconstruction in Cetoniidae (Coleoptera: Scarabaeoidea) and allows the interpretation of the evolution of larval feeding habits

Abstract.  The Cetoniidae, the showiest of scarabs, comprises some 3900 species in 515 genera, distributed worldwide except for subpolar areas and some offshore New Zealand islands. Parsimony analysis of 76 larval and adult characters and 42 terminal taxa supports the monophyly of Cetoniidae (sensu Krikken, 1984 ), but not of the traditionally considered subfamilies Cetoniinae and Trichiinae (sensu Krikken, 1984 ). In the study taxon, larval characters are shown to be more informative than those of adults for deeper phylogeny. The evolution of some larval characters (head and legs) in relation to feeding habits is discussed on the basis of phylogenetic analysis. The results show an evolutionary shift from wood associations to a higher ecological plasticity that allows the larvae to feed on wide sources of organic matter (including compost, dung, gopher burrows, packrat middens, ant debris piles, etc.).     

Dung pellets used to identify the distribution and density of dik‐dik

Estimates of the population density of elusive animals based on counts of dung deposits are often inaccurate. We report a refinement of this technique for territorial ungulates which exploits variation in pellet characteristics between individuals. In a study of Kirk's dik‐dik ( Madoqua kirki ) we found that pellet size and shape were less variable within individuals than between individuals. These findings were used to census a Kenyan population entirely on the basis of uniquely identifiable pellet groups, without any prior knowledge of the identity and location of individuals. The estimates were later compared with the results of an extensive capture and radio telemetry study. Population density estimated by the pellet‐matching method and by telemetry differed by less than 5%. In addition, only one border of 18 territories was incorrectly assigned, and only one territory was not detected. This represents a significant improvement in accuracy over indiscriminate dung counting techniques. We suggest that this method may also provide an accurate and non‐intrusive way of estimating population density in other solitary ungulates.