Search results for " Systematics."
showing 10 items of 4820 documents
Spatial and temporal pattern of neuroblasts, proliferation, and Engrailed expression during early brain development in Tenebrio molitor L. (Coleopter…
2003
Abstract In insects, the knowledge of embryonic brain development is still fragmentary, and comparative data are scarce. In this study, we explored aspects of embryonic brain development in the coleopteran Tenebrio molitor . A detailed description is provided of the spatial and temporal pattern of the embryonic brain neuroblasts during 18–60% of embryonic development. Approximately 125 brain NBs have been identified in each hemisphere of the brain at about 40% of embryonic development. A subset of five neuroblasts, among them the two progenitors of the mushroom bodies and two progenitors of the larval antennal lobe, are morphologically identifiable by their larger size. As revealed by incor…
Whole-genome analysis reveals contrasting relationships among nuclear and mitochondrial genomes between three sympatric bat species
2023
Understanding mechanisms involved in speciation can be challenging, especially when hybridization or introgression blurs species boundaries. In bats resolving relationships of some closely related groups has proven difficult due subtle interspecific variation both in morphometrics and molecular datasets. The endemic South American Histiotus bats, currently considered a sub-genus of Eptesicus, harbor unresolved phylogenetic relationships and of those is a trio consisting of two closely related species: Eptesicus (Histiotus) macrotus and E. (H.) montanus, and their relationship with a third, E. (H.) magellanicus. The three sympatric species bear marked resemblance to each other, but can be di…
Sex-specific genetic differences in endurance swimming of Trinidadian guppies.
2015
Abstract Swim performance is considered a main fitness‐determining trait in many aquatic organisms. Swimming is generally the only way most aquatic prey can escape predation, and swimming capacity is directly linked to food capture, habitat shifts, and reproduction. Therefore, evolutionary studies of swim performance are important to understand adaptation to aquatic environments. Most studies, however, concentrate on the importance of burst‐swim responses to predators, and little is known about its effect on endurance. Even fewer studies associate differences in organism swim capabilities to key gender‐specific responses. In this experiment, we assess the gender‐specific genetic basis of sw…
Ultraviolet reflectance of male nuptial colouration in sand lizards (Lacerta agilis) from the Pyrenees
2007
Abstract The evolutionary significance of lacertid colourations is relatively unexplored. However, several studies have demonstrated signalling by means of bright green colouration in Swedish Lacerta agilis males during the breeding season. Unfortunately, most of these studies have been based on human colour perception that differs in several ways from that of lizard. An important difference between human and lizard colour vision is the presence of an ultraviolet (UV) sensitive cone in lizards. The available evidence suggests that male sand lizards colorations do not reflect UV wavelengths, at least in Swedish populations. However, this study, based on objective (spectrophotometric) measur…
Pigment patterns in mutants affecting the biosynthesis of pteridines and xanthommatin in Drosophila melanogaster.
1986
Eye-color mutants of Drosophila melanogaster have been analyzed for their pigment content and related metabolites. Xanthommatin and dihydroxanthommatin (pigments causing brown eye color) were measured after selective extraction in acidified butanol. Pteridines (pigments causing red eye color) were quantitated after separation of 28 spots by thin-layer chromatography, most of which are pteridines and a few of which are fluorescent metabolites from the xanthommatin pathway. Pigment patterns have been studied in 45 loci. The pteridine pathway ramifies into two double branches giving rise to isoxanthopterin, “drosopterins,” and biopterin as final products. The regulatory relationship among the …
Coloration reflects behavioural types in the convict cichlid, Amatitlania siquia.
2015
9 pages; International audience; Interindividual behavioural differences, consistent over time and across situations, are frequently related to differences in reproductive success, susceptibility to disease and competitive ability. The behavioural phenotype of a conspecific is likely to affect the outcome of a social interaction, so an individual must be able to accurately assess behavioural phenotypes in order to optimize behavioural responses during mate choice, cooperative relationships and agonistic interactions. However, behavioural assessment based on dyadic interactions in different contexts can be costly because it may require significant time, increase the risk of predation and oft…
Stepping up to genome scan allows stock differentiation in the worldwide distributed blue shark Prionace glauca
2023
The blue shark Prionace glauca is a top predator with one of the widest geographic distributions of any shark species, yet classified as critically endangered in the Mediterranean Sea, and Near Threatened globally. Previous genetic studies did not reject the null hypothesis of a single global population across the worldwide species range. Blue shark situation was proposed as a possible archetype of the ‘grey zone of population differentiation’, coined to designate cases where population structure may be too recent or too faint to be detected using a limited set of markers. Here, blue shark samples collected throughout its global range were sequenced using a specific ddRAD method (DArTseq; G…
Climate signatures on decadal to interdecadal time scales as obtained from mollusk shells (Arctica islandica) from Iceland
2013
Abstract Pronounced decadal climate oscillations are detected in a multi-centennial record based on shell growth rates of the marine bivalve mollusk, Arctica islandica, from Iceland. The corresponding analysis of patterns in sea level pressure and temperature exhibit large-scale teleconnections with North Atlantic climate quantities. We find that the record projects onto blocking situations in the northern North Atlantic. The associated circulation shows a low-pressure signature over Greenland and the Labrador Sea and a high-pressure system over Western Europe associated with northeasterly flow towards Iceland and weakening in the westerly zonal flow over Europe. It can be speculated that s…
Allium aetnense (Amaryllidaceae), a new species from Sicily.
2013
A new species from Mt Etna (Sicily), Allium aetenense of A. sect. Codonoprasum, is described and illustrated. It is a diploid species (2n = 16) that grows on basaltic rocks in the mountain belt and shows close relationships with A. tenuiflorum of the Italian peninsula. Its morphology, karyology, leaf anatomy, seed coat microsculpturing, ecology and taxonomic position are examined.
On the discrimination of spatial intervals by the blind cave fish (Anoptichthys jordani).
1986
The performance of the blind cave fish in discriminating spatial intervals was investigated. The fish had to discriminate between pairs of grids consisting of equidistant vertical bars. The intervals between the bars on the grid to be chosen were kept constant while the intervals between the bars on the other grid were altered in steps so as to become gradually closer to the interval between the bars on the grid to be chosen. It was found that the fish were still able to discriminate between the two grids when the difference between the bar intervals amounted to at least 1.5 mm. In interpreting the results it was concluded that the phase information in the stimulus on the skin of the fish m…