Female mate preferences in Drosophila simulans: evolution and costs

Female mate preference is central to sexual selection, and all indirect benefit models require that there is genetic variation in female preference. This has rarely been tested however, with relatively few studies documenting heritable variation in female preference and even fewer that have directly selected on mate preference to unequivocally show that it can evolve. Additionally, costs of mate preference are poorly understood even though these have implications for preference evolution. We selected on female preference for ebony‐males in replicate Drosophila simulans lines, and generated a rapid evolutionary response in both replicates, with the proportion of females mating with ebony‐males increasing from approximately 5% to 30% after five generations of selection. This increase was independent of changes in ebony‐males as only females were included in our selection regime. We could detect no cost to mate preference itself other than that associated with the fitness consequences of mating with ebony males.     

Resistance to CO2 Fixation in the Submerged Aquatic Macrophyte Callitriche stagnalis Scop

The resistance to the photosynthetic carbon fixation in thefreshwater angiospcrm Callitriche stagnalis Scop was investigatedby gas exchange experiments in a closed water-flow system. Anelectrical analogue model was used to analyse uptake of carbonin terms of boundary layer resistance, cytoplasmic resistanceand carboxylation resistance. The most important rate-limitingfactor was the boundary layer resistance which was from 86%to 91 % of the total resistance of 852–1221 s cm^–1.The cytoplasmic and carboxylation resistances during activephotosynthesis were of minor importance being 89 s cm^–1and 24–30 s cm^–1, respectively. The calculated thicknessof the boundary layer surrounding the foliage of the shootswas 103–155 µm or 2–3 times the total thicknessof the leaves. The physiological and morphological characteristicsof submerged aquatic macrophytes are discussed as adaptationsto the low availability of carbon due to the high boundary layerresistance. Key words: Aquatic macrophytes, Resistance to carbon fixation, Adaptations     

Endemism and ecological islands: the ostracods from Jamaican bromeliads

1. The inhabitants of ecological islands, such as the phytolemata of bromeliad plants, provide an opportunity to examine the genetic patterns resulting from island radiations and draw inferences about modes of speciation.
2. Allozyme electrophoresis, as well as mitochondrial DNA and morphological analyses, were employed to delimit species boundaries and assess the population genetic structure of the ostracods from bromeliads on the island of Jamaica.
3. Nine species from the genus Elpidium were both sexually reproducing and endemic to the island. The other commonly encountered ostracod genus, Candonopsis , was represented by at least two sexually reproducing species.
4. Most Elpidium species showed very restricted distributions, low heterozygosity, and marked gene pool fragmentation, suggesting that population bottlenecks have occurred frequently. Whether founder events played a causal role in the diversification of these ostracods remains uncertain, but bromeliad habitats seem to be a source of high biodiversity, and may represent an ideal setting for extensive allopatric speciation.     

Synchronous Division of an Endosymbiotic Methanogenic Bacterium In the Anaerobic Ciliate Plagiopyla Frontata Kahl

ABSTRACT The life cycle of a methanogenic bacterium, symbiotic within the marine, free-living anaerobic ciliate Plagiopyla frontata , was studied using light microscopy and transmission electron microscopy (TEM). the bacteria are disc-shaped. During the growth phase of the host, bacteria and hydrogenosomes (organelles which ferment pyruvate into acetate and hydrogen) are arranged in conglomerates resembling stacks of coins in which bacteria and hydrogenosomes alternate; hydrogenosomes always cap the ends of the stacks. During the growth phase, numbers of hydrogenosomes and bacteria remain constant (about 5,000 and 3,500 per cell, respectively). Hydrogenosomes increase in volume shortly after cell division. Methanogens increase in volume slowly during the growth phase of the ciliate and rapidly when the ciliate begins to divide. the hydrogenosomes divide mainly during the initial phases of cell division while the methanogens divide synchronously during the last phase of ciliate division. the timing of reproduction of the symbionts is controlled by the host-cell cycle. the ciliate is known to receive an energetic advantage from its symbionts. the suppression of continuous bacterial reproduction may trigger the secretion of excess bacterial production as soluble organic compounds, for use by the ciliate.     

Historical incidence of Perthida leafminer species (Lepidoptera) in southwest Western Australia based on herbarium specimens

Examination of more than 500 herbarium specimens of Eucalyptus marginata and E. rudis for the presence of two species of leafminers, Perthida spp., indicated that these native insect species were very rare in southwest Western Australia until first recorded in metropolitan Perth in 1878 and 1897, respectively, when west coast populations of both leafminer species evidently increased dramatically. The first record from the south coast dates from 1901 near Albany. Evidence of leafminer populations on E. marginata remote from coastal settlements was not recorded until 1917, near Cranbrook. The first record in jarrah forest was in 1967, some 10 years after outbreaks of the pest insect are known to have occurred in the forest. The Perthida leafminer species on E. rudis was first recorded from inland areas in 1904 and appears to have increased more rapidly in abundance than the species found on E. marginata. These early geographical and species differences in incidence are discussed in terms of changing disturbance patterns, which have not been simultaneous across southwest Western Australia.     

Spatial variation in the magnitude and functional form of density‐dependent processes on the large skipper butterfly Ochlodes sylvanus

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Predicting Hot Spots of Herpetofauna Road Mortality Along Highway Networks

ABSTRACT Road mortality is often spatially aggregated, and there is a need for models that accurately and efficiently predict hot spots within a road network for mitigation. We surveyed 145 points throughout a 353-km highway network in New York State, USA, for roadkill of reptiles and amphibians. We used land cover, wetland configuration, and traffic volume data to identify features that best predicted hot spots of herpetofauna road mortality. We resampled 40 points an additional 4 times over 4 years to evaluate temporal repeatability. Both amphibian and reptile road mortality were spatially clustered, and road-kill hot spots of the 2 taxa overlapped. One survey provided a valid snapshot of spatial patterns of road mortality, and spatial patterns remained stable across time. Road-kill hot spots were located where wetlands approached within 100 m of the road, and the best predictor was a causeway configuration of wetlands (wetlands on both sides of the road). We validated causeways as predictors of road mortality by surveying 180 causeways and 180 random points across 5 regions (17,823 km²) of northeastern New York. Causeways were 3 times more likely than random locations to have amphibian and 12 times more likely to have reptile mortality present, and causeways had a 4 times higher total number of amphibian roadkill and 9 times higher reptile roadkill than did random points. We conclude it is possible to identify valid predictors of hot spots of amphibian and reptile road mortality for use when planning roads or when conducting surveys on existing roads to locate priority areas for mitigation.