Characterization of seven polymorphic microsatellites for the study of two Ranunculaceae: Ranunculus nodiflorus L., a rare endangered species and Ranunculus flammula L., a common closely related species

Ranunculus nodiflorus and Ranunculus flammula are two closely related Ranunculaceae. In France, the first one is rare and endangered, whereas the second is common. To compare their population genetic structure, seven polymorphic microsatellite markers were characterized. We found no polymorphism in R. nodiflorus, whereas R. flammula was polymorphic at each locus. The total number of alleles per locus varied from three to eight. Observed heterozygosities ranged from 0 to 0.261. This set of microsatellites offers an efficient tool to study population genetic structure and to compare the results between closely related endangered and common species.     

Beak morphology and song features covary in a population of Darwin's finches (Geospiza fortis)

Animal mating signals evolve in part through indirect natural selection on anatomical traits that influence signal expression. In songbirds, for example, natural selection on beak form and function can influence the evolution of song features, because of the role of the beak in song production. In this study we characterize the relationship between beak morphology and song features within a bimodal population of Geospiza fortis on Santa Cruz Island, Galápagos. This is the only extant population of Darwin's finches that is known to possess a bimodal distribution in beak size. We test the hypothesis that birds with larger beaks are constrained to produce songs with lower frequencies and decreased vocal performance. We find that birds with longer, deeper, and wider beaks produce songs with significantly lower minimum frequencies, maximum frequencies and frequency bandwidths. Results from the analysis of the relationship between beak morphology and trill rate are mixed. Measures of beak morphology correlated positively with 'vocal deviation', a composite index of vocal performance. Overall these results support a resonance model of vocal tract function, and suggest that beak morphology, a primary target of ecological selection in Darwin's finches, affects the evolution of mating signals. We suggest that differences in song between the two modes of the distribution may influence mate recognition and perhaps facilitate assortative mating by beak size and population divergence.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 489–498.     

The tree, the network, and the species

To enrich the Hennigian internodal conception of species, a new formalization of the definition of the species concept is proposed. This rigorous definition allows for considerable unification of the various, and sometimes conflicting, techniques of species delimitation used in practice. First, the domain of such a definition is set out, namely, the set of all organisms on Earth, past, present, and future. Next, the focus is on the genealogical relationship among organisms, which provides the key to analysing the giant or global genealogical network (GGN) connecting all these organisms. This leads to the construction of an algorithm revealing the topological structure of the GGN, from families to lineages, ending up with a definition of species as equivalence classes of organisms corresponding to branches of the 'tree of life'. Such a theoretical definition of the species concept must be accompanied by various recognition criteria to be operational. These criteria are, for example, the ill-named 'biological species concepts', 'phylogenetic species concepts', etc., usually, but wrongly, presented as definitions of the species concept. Besides clarifying this disputed point, the definition in the present study displays the huge diversity of the scales (time-scale and population size) involved in actual species, thus explaining away the classical problems raised by previous attempts at defining the species concept (uniparental reproduction, temporal depth of species, and hybridization).  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 89 , 509–521.     

Particle-Based Axenic Media for Tetrahymenids*

SYNOPSIS. Autoclavable, natural particulate media simplify axenic cultivation of tetrahymenid ciliates and presumably favor selection for phagotrophy. Viability is at least 2 months at room temperature (24–26 C) for the lipid-sensitive tetrahymenids Tetrahymena setosa, T. corlissi, T. paravorax, T. limacis, and T. patula, also for T. rostrata and (at 12 C), for strains of the T. pyriformis complex and Glaucoma chattoni. A typical medium consists of crude soy “lecithin”+ skim milk powder +Saccharomyces cerevisiae cells. Other useful particules readily available commercially are: whole liver powder, cells of Micrococcus lysodeikticus and Escherichia coli, and powdered residue of liver which had been extracted with 70% ethanol (liver #2). Preliminary experiments indicate that some of these media are suitable for the maintenance of Paramecium octaurelia stock 299S and Colpidium campylum. Such mixtures may serve as points of departure for devising media for more fastidious phagotrophs.     

Bee visits and the nectar of Echium vulgare L. and Sinapis alba L.

Abstract. 1. The time-course of anthesis of Echium vulgare is described.
2. Diel changes in the sugar concentration of the nectar, the quantity of nectar and the quantity of sugar per flower are illustrated for E.vulgare and for Sinapis alba.
3. These changes are interpreted in terms of (a) the periodicity of secretion and (b) the influence of microclimate and insect visits on post-secretory changes in the composition and volume of nectar.
4. There was hour-to-hour and day-to-day variation in the species composition and the proportion of workers taking nectar rather than nectar plus pollen among the social bees visiting E.vulgare.
5. Honeybee visits to E.vulgare were more numerous in humid weather, when there was enough nectar per flower for their relatively short tongues to reach, and in an area where the corollas grew shorter than they did elsewhere.
6. The significance of changes in the caloric content, volume, concentration, viscosity and sugar composition is discussed from the points of view of insects and ecologists.     

Are electrostatic forces involved in pollen transfer?

Abstract. The measurements of Yes'kov & Sapozhnikov (1976) suggest that electrostatic potentials on foraging honeybees can reach hundreds of volts. Pollen grains of oilseed rape, Brassica napus L., subjected experimentally to potentials of this order, jumped a distance that increased approximately as the square of the voltage, between two pin electrodes on which, in some experiments, were impaled an anther or stigma of oilseed rape or a freshly-killed honeybee. Most floral surfaces were insulated, but there was a low-impedance path to earth via the stigma, and the electrostatic field due to an approaching charged bee must therefore concentrate there. Thus, if electrostatic potentials of this magnitude occur in nature they may increase the chance that pollen from bees will reach the stigma rather than other floral surfaces, as well as enabling pollen to jump from anther to bee and from bee to stigma across an air gap of the order of 0.5 mm.     

Impact of the fish Garra on the ecology of reservoirs and the occurrence of Microcystis blooms in semi-arid tropical highlands: an experimental assessment using enclosures

1. Many man‐made reservoirs in the semi‐arid highlands of Northern Ethiopia (Tigray) are characterised by the occurrence of intensive blooms of cyanobacteria and a dominance of small riverine fishes belonging to the genus Garra. 2. We carried out enclosure experiments to test for the effect of these small fish on abiotic characteristics, phytoplankton biomass and zooplankton community structure in the pelagic of two reservoirs (Gereb Awso and Tsinkanet). Two experiments were carried out in each of the reservoirs, one at the end of the rainy season (highest water level) and one at the end of the dry season (lowest water level). 3. The presence of Garra in general increased the amount of suspended matter, nutrient concentrations (total nitrogen and total phosphorus), phytoplankton and Microcystis biomass (including the proportion of Microcystis in the phytoplankton community), and reduced water transparency. The positive effect of the presence of Garra on nutrient concentrations and phytoplankton productivity indicate that Garra has the potential to affect food web functioning indirectly through bottom‐up effects, by enhancing nutrient concentrations through sediment resuspension and excretion of nutrients. Indeed, population densities of the cladoceran zooplankton taxa Ceriodaphnia and Diaphanosoma also showed an overall increase in enclosures with Garra. 4. However, our data also provide some evidence for a potential of Garra to exert top‐down control on large bodied daphnids (Daphnia carinata, D. barbata), although such effect varied among experiments. The limited capability of Garra to control zooplankton communities mainly reflects the low efficiency of these small, riverine and benthos‐oriented fish in foraging on zooplankton and suggests the existence of an unoccupied niche for zooplanktivorous fish in the majority of the reservoirs. 5. Although the main effects of Garra on the pelagic food web seemed to be mediated by bottom‐up mechanisms, our results also indicate that one of the key variables, the relative abundance of Microcystis, was impacted by Daphnia‐mediated trophic cascade effects.     

Characterization of 18 SNP markers for sperm whale (Physeter macrocephalus)

We report the characterization of 18 new single nucleotide polymorphism (SNP) markers for an endangered species, the sperm whale (Physeter macrocephalus), developed using a targeted gene approach. SNP markers were derived from autosomal regions of the genome using primers originally characterized for genome mapping in other mammals. These SNP markers are the first to be designed for genotyping sperm whale populations and will provide a necessary addition to the genetic tools employed for understanding population structure on a global scale and for developing a conservation management strategy for this endangered species.     

Evolutionary divergence of field and laboratory populations of Manduca sexta in response to host‐plant quality

1. The tobacco hornworm, Manduca sexta, has been an important model system in insect biology for more than 50 years. In nature, M. sexta successfully utilises a range of host plants that vary in quality. The consequences of laboratory domestication and rearing on artificial diet for fitness of phytophagous insects on natural host plants have not been explored. 2. We examine the evolutionary divergence of two domesticated laboratory populations and a field population (separated for more than 40 years, or > 250 laboratory generations) of M. sexta with respect to performance and fitness on two natural host plants: a typical host plant, tobacco (Nicotiana tabacum) and a novel host plant, devil's claw (Proboscidea louisianica). 3. For both field and laboratory populations, rearing on devil's claw resulted in animals with lower survival, smaller final size, longer development time, and reduced size‐corrected fecundity than animals reared on tobacco. Reductions in some fitness components (survival and fecundity) were greater for the laboratory population animals than the field population animals. 4. When reared on tobacco, the laboratory population animals had similar or larger pupal masses and slightly shorter development times than when reared on artificial diet, suggesting that laboratory domestication on artificial diet has not greatly affected the ability of M. sexta to perform well on a typical natural host plant. 5. Although field and laboratory populations exhibited qualitatively similar responses to host‐plant quality, i.e. reduced performance on devil‘s claw, the magnitude of this reduction differed across populations, with the domesticated laboratory populations having greater reductions in performance than the field population. The use of domesticated populations as models for responses of field populations may therefore be more appropriate for considering environmental conditions that are relatively benign or near‐optimal, than when exploring responses to extreme or stressful conditions.