Habitat use, but not gene flow, is influenced by human activities in two ecotypes of Egyptian fruit bat (Rousettus aegyptiacus).

Understanding the ecological, behavioural and evolutionary response of organisms to changing environments is of primary importance in a human-altered world. It is crucial to elucidate how human activities alter gene flow and what are the consequences for the genetic structure of a species. We studied two lineages of the Egyptian fruit bat (Rousettus aegyptiacus) throughout the contact zone between mesic and arid Ecozones in the Middle East to evaluate the species' response to the growing proportion of human-altered habitats in the desert. We integrated population genetics, morphometrics and movement ecology to analyse population structure, morphological variation and habitat use from GPS- or radio-tagged individuals from both desert and Mediterranean areas. We classified the spatial distribution and environmental stratification by describing physical-geographical conditions and land cover. We analysed this information to estimate patch occupancy and used an isolation-by-resistance approach to model gene flow patterns. Our results suggest that lineages from desert and Mediterranean habitats, despite their admixture, are isolated by environment and by adaptation supporting their classification as ecotypes. We found a positive effect of human-altered habitats on patch occupancy and habitat use of fruit bats by increasing the availability of roosting and foraging areas. While this commensalism promotes the distribution of fruit bats throughout the Middle East, gene flow between colonies has not been altered by human activities. This discrepancy between habitat use and gene flow patterns may, therefore, be explained by the breeding system of the species and modifications of natal dispersal patterns.

Fire-induced population reduction and landscape opening increases gene flow via pollen dispersal in Pinus halepensis.

Population reduction and disturbances may alter dispersal, mating patterns and gene flow. Rather than taking the common approach of comparing different populations or sites, here we studied gene flow via wind-mediated effective pollen dispersal on the same plant individuals before and after a fire-induced population drop, in a natural stand of Pinus halepensis. The fire killed 96% of the pine trees in the stand and cleared the vegetation in the area. Thirteen trees survived in two groups separated by ~80 m, and seven of these trees had serotinous (closed) prefire cones that did not open despite the fire. We analysed pollen from closed pre and postfire cones using microsatellites. The two groups of surviving trees were highly genetically differentiated, and the pollen they produced also showed strong among-group differentiation and very high kinship both before and after the fire, indicating limited and very local pollen dispersal. The pollen not produced by the survivors also showed significant prefire spatial genetic structure and high kinship, indicating mainly within-population origin and limited gene flow from outside, but became spatially homogeneous with random kinship after the fire. We suggest that postfire gene flow via wind-mediated pollen dispersal increased by two putative mechanisms: (i) a drastic reduction in local pollen production due to population thinning, effectively increasing pollen immigration through reduced dilution effect; (ii) an increase in wind speeds in the vegetation-free postfire landscape. This research shows that dispersal can alleviate negative genetic effects of population size reduction and that disturbances might enhance gene flow, rather than reduce it.

Effects of prenatal exposure to gamma rays on circling and activity behavior in prepubertal and postpubertal rats.

The study departs from the finding that postural asymmetries in low-weight female neonates are greatly increased following prenatal lesions inflicted by gamma irradiation at day 15. Given that amphetamine-induced rotation in adult rats could be predicted by their infantile axial asymmetry we expected a greater tendency for circling in rats exposed at day 15. To examine this prediction, Sprague-Dawley rats were exposed to a single dose of gamma radiation at 1.5 Gy with a dose-rate of 0.15 Gy/min. The dose was delivered on one of the embryonic days (E15, 17 or 19) throughout the whole body of pregnant dams. Sham prenatal exposure of controls consisted of placing pregnant rats in the same environment for 10 min. All rats were tested during the active part of the circadian cycle. At postnatal day 27 (P27) exposed pups did not differ in rates of either spontaneous or d-amphetamine-induced circling from the shams. At P57, in keeping with our prediction, E15 rats manifested enhanced rotation and higher net asymmetry. However, E17 also showed higher gyration tendency compared to their shams while exposed E19 rats did not differ from their shams. The role of intrinsic DAergic imbalance presumably sharpened by irradiation at E15 and of neocortical deficit inflicted at E15 and E17 are discussed.