Determination of growth rate provides an important component of an organism’s life history, making estimations of size at maturity, survival rate, and longevity possible. Here, we report on growth rate of males and females of the tropical tree lizardUrosaurus bicarinatus, in a seasonal environment in the state of Jalisco on the Mexican Pacific Coast. We calculated body growth rates and fitted these to the Von Bertalanffy, the logistic-by-length, and the logistic-by-weight growth models. The Von Bertalanffy model provided the best fit, and we used it to analyze the growth pattern. Males and females did not differ in estimated asymptotic size and other characteristic growth parameters. Estimated growth curve predicted an age at maturity of 38 mm SVL on 120 days for males, and 40 mm SVL on 170 days for females. On the basis of the similarities in the growth rates between the sexes, comparisons were made between seasons, and we found that the average rate of growth was slightly, albeit insignificantly, higher in the rainy season than in the dry season. The similarities in the growth patterns for the sexes of this species might be indicative of variance in its life history traits (e.g., fecundity, egg size) compared to those of other populations of this species and other species of this genus; therefore, it is important to document interpopulation differences to understand the evolutionary changes that have led to optimal adaptation in a particular environment more accurately.

Declines in populations of capercaillie (Tetrao urogallus) and black grouse (Lyrurus tetrix) have been reported from both Central Europe and the continuous boreal forests of Fennoscandia. While intensified land-use is assumed to be the underlying cause of these declines, the mechanisms are not yet understood. Predation is the proximate cause of mortality of eggs, chicks and adults throughout capercaillie and black grouse ranges, but the link between predation and habitat and/or climate change remains unclear. To investigate temporal trends in reproductive output of woodland grouse, we collated previously published and unpublished data of reproduction in capercaillie and black grouse throughout their ranges from 1930 to 2012. We show that, overall, reproductive success has decreased and stabilized at low levels in most regions whilst capercaillie reproductive output in Scotland is still declining. With today’s net reproduction, capercaillie and black grouse adult survival is too low to compensate for reproduction declines. Consequently, populations are expected to further decline unless reproductive performances improve. We put our findings in the context of changes in land use, climate and generalist predator numbers. By critically reviewing how these factors limit reproductive success in capercaillie and black grouse, we hope to shed light on the underlying mechanisms causing the decline. Our results imply that measures should be undertaken to reduce mortality of capercaillie and black grouse chicks and eggs. We suggest that future studies should aim to better understand which predators limit capercaillie and black grouse populations and how predation rates are mediated by continuously changing habitat and climate.

Temperature directly affects survival, development and reproduction in insects and thereby it is a key environmental driver for geographic distribution and population dynamics. This study aims at testing the survival ofDrosophila melanogasterunder constant low temperatures (CLTs) (2, 3, 4, and 5°C)vs.fluctuating thermal regimes (FTRs). In the latter, the cold stress period was interrupted daily by 2 h pulses at 20°C. Since acclimation enhances cold tolerance, we tested whether benefits of acclimation can combine with those of FTRs. SinceD. melanogasteroverwinters as non-reproductive adults, we tested if actively reproducing adults are more susceptible to cold stress than virgin females that have a much reduced reproductive activity. The results show that short interruptions of cold stress enhanced survival of adult flies. Survival was time- and temperature-dependent. Prior acclimation to low temperature allowed flies to better cope with cold stress under CLTs. On the other hand, acclimated flies did not profit from the benefits of FTRs and even showed lower survival under FTRs, probably because flies deacclimated during the periodic warm intervals. Gravid females were overall less cold tolerant than virgin females, and both survived better under FTRs. Cold survival at pupal stage was much lower than at adult stage, and no clear benefit of FTR was observed in this life stage. Our study highlights critical variables to take into account when designing experiments of prolonged exposure to low temperature in insects.

Pymetrozine represents a class of compounds for the control of sucking insects. However, chewing insects have also shown sensitivity to this compound. Therefore, although pymetrozine has been demonstrated to have a direct action on sucking insects, it could also affect species like the boll worm Anthonomus grandis by promoting histological changes in the intestine and alterations in biochemical parameters such as glycogen, lipids, and glucose. The pymetrozine promoted histological changes are characterized by protrusions and detachments of columnar cells toward the intestinal lumen, presence of vacuolated regenerative cells, and removal of the epithelial lamina in some areas of the muscle layer. The ultrastructure of the midgut in the control group exhibited the basal labyrinth near the mid region of the cell, rough endoplasmic reticulum, Golgi complex, glycogen granules, mitochondria, electron-lucent vesicles, nucleus with well-defined nucleoli, and elongated microvillus. Pymetrozine promoted disarrangement in the basal labyrinth and generated numerous vacuoles and large protrusions between the epithelial lamina and muscular layer. No significant difference was observed in glucose content at 48 h after treatment; however, a significant increase was observed at 144 h after treatment. The glycogen content was reduced in the first 48 h of exposure to pmetrozine and reached the average content of the control insects at 144 h. Significant effects were observed in lipid contents, both in the first 48 h and at 144 h after treatment. Thus, we conclude that pymetrozine compromises the digestive physiology in these insects, affects reproduction, and consequently, it can be a potential alternative to reduce this pest species.

There are significant gaps in our knowledge of wild camel ecology; especially the activity patterns that allow them to adapt to desert environments. The wild Bactrian camel (Camelus bactrianus) is a critically endangered species that survives in the extreme desert conditions of Central Asia. We conducted camera trapping surveys at seven watering sites in the northern piedmont of the Altun Mountains from 2010 to 2012. We analyzed the frequency of photo-captures to elucidate the wild camels’ diel activity patterns, and the seasonal variation in their activity at watering sites. We found that these wild camels were predominantly diurnal at watering sites, with an increase in relative activity from sunrise, reaching a peak toward midday, and then gradually decreasing in activity until sunset. The camels visited watering sites more often in winter than in summer. These results provide a guide for water development in the conservation of ungulates in arid areas.

Tail autotomy is an efficient predator escape form, but imposes locomotor costs in many lizard species. It has been hypothesized that locomotor impairment following tail autotomy results from the altered running dynamics or loss of energy available for locomotion, but there is a paucity of data available to demonstrate such effects. We evaluated the locomotor costs of tail loss in a viviparous skink, Sphenomorphus indicus, and examined whether locomotor costs were related to changes in gait characteristics and metabolic rate. Of 24 field-captured adult males with original intact tails, 12 individuals were used as experimental animals, and the remaining 12 as controls. Locomotor performance and CO2 production were measured for the experimental skinks before and after tail removal; the same parameters were measured at the same time for the control skinks. Compared with tailed skinks, the mean locomotor speed and stamina of tailless skinks was reduced by approximately 26% and 17%, respectively. At any given speed, tailless skinks had a shorter stride length for hindlimbs (but not for forelimbs) and a greater stride frequency than did tailed skinks. In S. indicus, locomotor impairment may be a result of the reduced stride length, and energetic constraints on stride frequency. We found no significant change in standard metabolic rate after the skinks underwent tail removal, which may reflect a minor effect on energy expenditure for maintenance. Although the reduction in metabolically active tissue might cause a lower metabolic rate, tail regeneration counteracted such an effect because it was energetically expensive.

Metabolic scaling (i.e., the relationship between the size and metabolic rate of organisms) has been suggested to explain a large variety of biological patterns from individual growth to species diversity. However, considerable disagreement remains regarding the underlying causes of metabolic scaling patterns, and what these patterns are. As in all biology, understanding metabolic scaling will require understanding its evolution by natural selection. We searched for evidence of natural selection on metabolic scaling indirectly by manipulating the genetic quality of male and female Drosophila montana flies with induced mutations and inbreeding, building on the notion that mutations and inbreeding will cause predictable changes in characters under directional selection. Irradiation-induced mutations had no effect on the examined traits, most likely because of purging at an early stage. However, inbreeding increased the energy use of larger females, suggesting that selection has favoured low metabolic scaling in females. Inbreeding did not affect metabolic scaling of males. Together, our results suggest that natural selection on metabolic scaling acts differently on the sexes, depending on the relative importance of body size and energetic efficiency to individual fitness. The results call attention to the important notion that size-specific energy use can be an evolutionarily malleable trait.

The mandibles of bees contain two types of tegumental glands whose function is not clear, despite the hypotheses put forward by several researchers. Although these glands have been found in all the bee species studied so far, observations have been confined mostly to workers of eusocial species in the forager phase. The work reported here involved a study of the morphology of the glands of newly emerged, nurse and forager workers, virgin and fecundated queens, and newly emerged and sexually mature males of Scaptotrigona postica, seeking to identify changes that may be linked to the bee’s life phase. Our findings indicate that the two types of glands are present in the species but not in all life phases or individual classes. The glands consisting of class I cells, the epithelial glands are present only in forager workers and fecundated queens. Glands of type III cells were studied in detail, and gland size was estimated from histological sections. The degree of development of the glands varies according to individual classes and life phases, suggesting different functions during the individual’s life and from one individual to another.

Brown trout is considered as a territorial fish, in which negative density effects on growth and survival rates can be mediated through competition mechanisms. Here, in order to examine whether competition mechanisms can affect the foraging behaviour of wildSalmo truttawith respect to active-bottom, benthic-drift or surface-drift foraging, three neighbouring populations under different levels of fish density (high, intermediate and low) were studied. We analysed the foraging behaviour of each population according to niche breadth, prey preferences, the modified Costello graphical method and prey trait analysis. The results revealed a remarkable similarity in the feeding behaviour among these feral fish populations, suggesting a foraging behaviour convergence in response to site-specific prey accessibility. A generalist foraging behaviour was the prevailing feeding strategy, independent of fish density. Hence, this study offered evidence for the occurrence of density-independent individual foraging behaviour when food is abundant and available; however, density-dependent foraging behaviour might occur when resource limitation exists. Studies under natural conditions like the present study are needed to increase ecological realism, and indeed this study opens promising research directions for future feeding studies in territorial fish species.

Food composition of the Eurasian badger Meles meles was studied in the mountain zone and foothills of the Western Carpathians (Southern Poland). The diet, obtained by scat analysis, was compared with availability of earthworms, fruits, amphibians, rodents and ground nesting birds (capercaillie Tetrao urogallus and hazel grouse Bonasa bonasia) within both altitudinal zones. Earthworms and fruits were the most abundant food source in the foothills, while amphibians were scarce and rodents were equally available in both altitudinal zones. Capercaillie and hazel grouse occurred in the forests above 560 m a.s.l. In the foothills, vegetable matter (mainly fruits), constituted 56.3%, and earthworms 39.6%, of the biomass consumed, while mammals were supplementary resources (2.9%). In the mountains, the importance of vegetable matter was smaller (47.9%). Earthworms and insects had a similar share (37.8% and 1.8%, respectively), but mammals were eaten much more intensively (13.9%). Birds (exclusively domestic hen) were taken by badgers only in the foothills (0.6%). There was a seasonal variation in badger diet composition in both altitudinal zones, as earthworms dominated in spring, while fruits were eaten mainly in summer and autumn. The composition of the badgers’ diet only slightly differed between foothills and mountains. This was probably caused by regular movement of badgers between elevational zones during foraging. We conclude that the present hunting regulation, which allows year-round hunting on badgers in areas inhabited by capercaillie, is not justified.