In order to assess the impact of seed removal and seedling establishment for four species of pines, we designed experiments with and without the exclusion of seed removers in three vegetation types (pine forest, oak-alder forest, and subalpine grassland). Seed removal was significantly different between species of pines (P \ 0.01), as was the interaction between the vegetation types and category of exclusion (remover) (P \ 0.0001). The significant difference in terms of seed removal was between P. patula and P. montezumae (33.0 and 17.9%, respectively). Seed removal was significant between pine forest-without exclusion (20.0%) versus oakalder forest-without exclusion (7.0%). There was significant interaction between seedling establishment of the pine species and vegetation type (P \ 0.0001). Highlighting differences between the pine forest-P. teocote (84.1%) versus oak-alder forest-P. patula (19.0%), oak-alder forest-P. pseudostrobus (45.0%), pine forest-P. patula (20.2%), pine forest-P. pseudostrobus (45.6%), subalpine grassland-P. montezumae (24.3%), subalpine grassland-P. patula (27.9%), and subalpine grassland-P. pseudostrobus (17.5%). The impact of the food preferences of rodents and other granivores for P. patula and P. pseudostrobus seeds, as well as the poor survival of seedlings of these species in the pine and oak-alder forest are both factors which may explain the dominance of P. teocote in the study region.
The distribution of the nests of marine turtles on beaches is one of the most important factors for hatchling success. Beaches with fine sands, moderate slopes and good humidity and drainage, are the main environmental variables for ovoposition. The objective of this investigation was to determine the nesting variations of the green turtle during which the nesting frequency per year, beach morphology and distance from the nests to the tidal line were registered. During the nesting seasons, 1 654 nests were registered on 13 beaches, among which significant differences in the number of nests per month were noted (f= 14.07; p< 0.05). Central beaches displayed major nesting probability and included beaches with short distances from the intertidal zone to the supralittoral zone. Dunes were the sites with greater preference for oviposition, being different from the sandy beaches and the intertidal zone (f=54.68; p< 0.05). Significant differences were found in the location of the nests with respect to the tidal line (t=2.33; p< 0.05), and the greatest intervals for nesting were between 10 and 24 m from the tidal line. The area displayed beaches with moderate slopes and dunes with an average distance of 22.6 m from the tidal line. This area is the most important nesting site for green turtle in the American Continent.
Survival and mating success are traits of quality in mass-reared sterile males. Thus, studying the trade-offs between these traits may help to improve process in the sterile insect technique (SIT). Here, we tested the hypothesis that modifying individual metabolism, especially of energetic reserves, may reduce the negative impact of an early reproduction on the survival of Anastrepha ludens flies. Appling metformin (a drug used to treat type II diabetes) that improves insects’ survival, through dietary restriction mimicry, and methoprene (a juvenile hormone analogue) that accelerates the age to reproduction in insects, we explore the dynamic of this trade-off. We fed A. ludens flies with metformin, methoprene, or a mixture of metformin–methoprene for five consecutive days. We determined the effect of these treatments on the fecundity and fertility (number of eggs and percentage of hatching) of females, on sexual maturation and mating success of males, and on the survival of both sexes. The results showed that the acceleration in sexual maturation by the action of methoprene significantly reduced survival in both sexes of two different fly strains. However, adding metformin to the diet buffered this negative effect, without reducing the mating propensity compared with the males treated only with methoprene. The response to metformin was sex-specific since females responded to high doses of the substance, whereas males responded better to low doses. These results suggest that trade-offs between survival and reproduction do not necessarily depend on energy reserves but they are intrinsically related to metabolic regulation and hormonal control.
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