63 research outputs found
Male-female interactions drive the (un)repeatability of copula duration in an insect.
Across the animal kingdom the duration of copulation varies enormously from a few seconds to several days. Functional explanations for this variation are largely embedded within sperm competition theory in which males modulate the duration of copula in order to optimise their fitness. However, copulation is the union of two protagonists which are likely to have separate and often conflicting reproductive interests, yet few experimental designs specifically assess the effect of male-female interactions on the duration of copulation. This can result in inexact assertions over which sex controls copulatory behaviour. Here we analyse the repeatability of copulatory behaviour in the seed beetle Callosobruchus maculatus to determine which sex exerts primary influence over copulation duration. In C. maculatus, copulation follows two distinct phases: an initial quiescent phase followed by a period of vigorous female kicking behaviour that culminates in the termination of copulation. When males or females copulated with several novel mates, copulatory behaviour was not significantly repeatable. By contrast, when males or females mated repeatedly with the same mate, copula duration was repeatable. These data suggest copulatory behaviour in C. maculatus to be largely the product of male-female interactions rather than the consistent, sex-specific modulation of copula duration of one protagonist in response to the phenotypic variation presented by the other protagonist
Intra-ejaculate sperm selection in female zebra finches
Among internal fertilizers, typically fewer than 1% sperm survive the journey through the oviduct. Several studies suggest that the sperm reaching the ovum-the 'fertilizing set'-comprise a non-random sub-population, but the characteristics of this group remain unclear. We tested whether oviductal selection in birds results in a morphologically distinct subset of sperm, by exploiting the fact that the fertilizing set are trapped by the perivitelline layer of the ovum. We show that these sperm have remarkably low morphological variation, as well as smaller head size and greater tail length, compared with those inseminated. Our study shows that the morphological composition of sperm-rather than length alone-influences success in reaching the ovum
Effects of different segmentation methods on geometric morphometric data collection from primate skulls
1. An increasing number of studies are analysing the shapes of objects using geometric morphometrics with tomographic data, which are often segmented and transformed to threeâdimensional (3D) surface models before measurement. This study aimed to evaluate the effects of different image segmentation methods on geometric morphometric data collection using computed tomography data collected from nonâhuman primate skulls. 2. Three segmentation methods based on a visually selected threshold, a halfâmaximum height protocol and a gradient and watershed algorithm were compared. For each method, the efficiency of surface reconstruction, the accuracy of landmark placement and the level of variation in shape and size compared with various levels of biological variation were evaluated. 3. The visualâbased method inflated the surface in highâdensity anatomical regions, whereas the halfâmaximum height protocol resulted in a large number of artificial holes and erosion. However, the gradientâbased method mitigated these issues and generated the most efficient surface model. The segmentation method used had a much smaller effect on shape and size variation than interspecific and interâindividual differences. However, this effect was statistically significant and not negligible when compared with intraâindividual (fluctuating asymmetric) variation. 4. Although the gradientâbased method is not widely used in geometric morphometric analyses, it may be one of promising options for reconstructing 3D surfaces. When evaluating small variations, such as fluctuating asymmetry, care should be taken around combining 3D data that were obtained using different segmentation methods
Genetic distinctiveness of rye in situ accessions from Portugal unveils a new hotspot of unexplored genetic resources
Rye(SecalecerealeL.)is a cereal crop of major importance in many parts of Europe and rye breeders are presently very concerned with th e restrict pool of rye genetic resources available.Such narrowing of rye genetic diversity results from the presence ofâPetkus âpool in most modern rye varieties as well as âPetkusâĂâCarstenâ heterotic pool in hybrid rye breeding programs.Previous studies on ryeâs genetic diversity revealed more over a common genetic background on landraces(exsitu) and cultivars,regardless of breeding level or geographical origin.Thus evaluation of in situ populations is of utmost importance to unveil âonfarmâ diversity,which is largely undervalued.Here,we perform the first comprehensive assess ment of ryeâs genetic diversity and population structuring using cultivars,exsitu landraces along a comprehensive sampling of insitu accessions from Portugal,through amolecular-directed analysis using SSRs markers.Rye genetic diversity and population structure analysis does not present any geographical trend but disclosed marked differences between genetic backgrounds of in situ accessions and those of cultivars/exsitu collections.Such genetic distinctiveness of insitu accessions highlights their unexplored potential as new genetic resources,which can be used to boost rye breeding strategies and the production of new varieties.Overall,our study successfully demonstrates the high prospective impact of comparing genetic diversity and structure of cultivars,exsitu,and in situ samples in ascertaining the status of plant genetic resources (PGR)info:eu-repo/semantics/publishedVersio
Mining for treatment-specific and general changes in target compounds and metabolic fingerprints in response to herbivory and phytohormones in *Plantago lanceolata*
Sutter R, MĂŒller C. Mining for treatment-specific and general changes in target compounds and metabolic fingerprints in response to herbivory and phytohormones in *Plantago lanceolata*. New Phytologist. 2011;191(4):1069-1082
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