Invasion of Drosophila virilis by the Penelope transposable element

The Penelope family of transposable elements (TEs) is broadly distributed in most species of the virilis species group of Drosophila. This element plays a pivotal role in hybrid dysgenesis in Drosophila virilis, in which at least four additional TE families are also activated. Here we present evidence that the Penelope family of elements has recently invaded D. virilis. This evidence includes: (1) a patchy geographical distribution, (2) genomic locations mainly restricted to euchromatic chromosome arms in various geographical strains, and (3) a high level of nucleotide similarity among members of the family. Two samples from a Tashkent (Middle Asia) population of D. virilis provide further support for the invasion hypothesis. The 1968 Tashkent strain is free of Penelope sequences, but all individuals collected from a 1997 population carry at least five Penelope copies. Furthermore, a second TE, Ulysses, has amplified and spread in this population. These results provide evidence for the Penelope invasion of a D. virilis natural population and the mobilization of unrelated resident transposons following the invasion.     

Penelope as Dreamer: A Reading of Book 19 of The Odyssey

This essay reexamines the encounter between Odysseus and Penelope in Book 19 of Homer's epic poem The Odyssey, focusing particular attention on the dream of the 20 geese Penelope describes during that encounter. Odysseus, disguised as a beggar, says the dream is a favorable omen which indicates the real Odysseus will return soon to rid his palace of the hated suitors who have occupied it in his long absence. Although generations of scholars have agreed with the hero's interpretation, the present essay offers a different understanding: Penelope, having recognized who this beggar really is, has fabricated her dream of the 20 geese to test her husband and determine whether he is more interested in renewing their marriage or satisfying his vengeance against the suitors. The essay offers an appreciation of Penelope as one of our earliest and wisest dreamers, who understood how easily people's wishes and desires could lead them to misinterpret their own dreams and the dreams of others.     

The Evolutionary History of the Transposable Element Penelope in the Drosophila virilis Group of Species

We have used phylogenetic techniques to study the evolutionary history of the Penelope transposable element in the Drosophila virilis species group. Two divergent types of Penelope have been detected, one previously described, clade I, and a new one which we have termed clade III. The phylogeny of some copies of the Penelope clade I element was partially consistent with the species phylogeny of the D. montana subphylad, suggesting cospeciation and allowing the estimation of the evolutionary rate of Penelope. Divergence times of elements found in different species are younger than the age of the species, suggesting horizontal transfer events. Electronic Supplementary Material Electronic Supplementary material is available for this article at and accessible for authorised users. [Reviewing Editor: Dr. Dmitri Petrov]     

Habitat use,density, and conservation status of the white-browed guan (Penelope jacucaca Spix, 1825)

The white-browed guan (Cracidae: Penelope jacucaca) is an endemic bird species to the Caatinga, the largest centre of dry forest in South America. This taxon was considered Vulnerable by the International Union for Conservation of Nature (IUCN) due to continued habitat loss within its distribution and intense hunting pressure that contributed to population declines. However, information on population aspects and habitat use by P. jacucaca, which is fundamental for monitoring its conservation status, is not available. We studied habitat use (analysed in a Generalized Linear Model) and population density (estimated by distance sampling) in a specific area in Northeast Brazil. Using species distribution modelling (SDM), forest cover loss data (performed in the MaxEnt program) and quantitative information about hunting, more rigorous estimates of the distribution limits, available habitat, and population declines of P. jacucaca were generated. Based on the IUCN criteria, we applied analysed data to reassess the conservation status of the white-browed guan. Local density was estimated at 13.1 individuals/km² and the estimated number of individuals removed per year due to hunting was 121.7 in the forest cover area (110.46 km²) of the Serra de Santa Catarina. Consequently, the annual removal rate of hunted individuals in the study area corresponds to approximately 11% of the population. The habitat use analysis pointed to a strong positive association with seasonally dry deciduous forest (SDDF) vegetation and with arboreal vegetation. The SDM indicated a potential distribution (climatically favourable) area of 675,823 km², and forest cover and loss calculations indicated a total of 81,307 km² of available suitable habitat in 2013. Therefore, comparing these results to the IUCN criteria, we recommend that P. jacucaca remain in the Vulnerable category.