Distinguishing effects of juvenile mortality and dispersal on recruitment

Detailed data on juvenile survival are rare in the literature. Although many studies estimate recruitment, if you cannot distinguish between permanent dispersal and mortality, the management implications for a population may be unclear. We estimated juvenile survival in a reintroduced North Island robin (Petroica longipes) population in a protected sanctuary surrounded by an unprotected landscape where the species is extirpated. The population has had marginal population growth due to poor recruitment so we modeled 3 types of data (resighting of fledglings, radio-telemetry of independent juveniles, resighting of adults) in an integrated framework to determine the life stages where high mortality was occurring, and to distinguish mortality from dispersal. Approximately 16% of birds that fledged (n = 109) were present at the start of the next breeding season, consistent with recruitment rates from previous years. Low survival in the first 6 weeks after fledging was the primary cause of poor recruitment. Only 50% survived to independence (4 weeks after fledging), and 18% survived to the end of the radio-tracking period (14 weeks), after which juvenile survival matched adult survival. No dispersal from the sanctuary occurred during the radio-tracking period. Juveniles moved between adjacent forest fragments within the sanctuary, but did not leave the sanctuary. This information, which demonstrates the importance of distinguishing between natal mortality and dispersal, is important for ongoing management of the site and selection of future reintroduction sites for this species. © 2019 The Wildlife Society.     

Age structure and multi-model growth estimation of longnose stingray Hypanus guttatus (Dasyatidae: Myliobatoidei) from north-east Brazil

We collected 729 Hypanus guttatus from the northern coast of the state of Rio Grande do Norte (RN), of which 196 were used to estimate age and growth. Ninety-five were male (12.7 to 57.0 cm disc width; W_D) and 101 were female (13.0 to 88.5 cm W_D); females were significantly larger than males. Cross sections of vertebrae showed band-pairs ranging from 0 to > 14 in females and from 0 to 9 in males. New-borns presented an opaque edge at birth in vertebrae without a birthmark. The average percentage of error (APE; %E) for the entire sample provided evidence that ages were repeatable. The mean monthly marginal increment (I_M) indicates annual band-pair formation from August to November. The annual cycle model for one band-pair deposition provided the best fit to data based on the AIC, with peaks between August and October, similar to that found in the I_M analysis, suggesting an annual formation pattern. A multi-model approach that included four models based on the observed mean W_D at age indicated a modified von Bertalanffy growth model as the best for describing the species growth: W₀ (W_D at birth) = 14.6 cm for both sexes; females W_∞ = 98.61 cm (95% CI = 87.34–114.61 cm); k = 0.112 year⁻¹ (CI = 0.086–0.148 year⁻¹); males W_∞ = 60.22 cm (CI = 55.66–65.35 cm); k = 0.219 year⁻¹ (CI = 0.185–0.276 year⁻¹). The age-at-maturity in males and females is 5 years and 7 years, respectively. The age composition shows that most (84%) specimens were aged 0 to 2 years. The information provided here is essential for analytical assessments of H. guttatus, which is subject to significant fishing pressure mainly on new-borns and juveniles.     

Flight initiation distance and escape behavior in the black redstart (Phoenicurus ochruros)

There are many anti‐predatory escape strategies in animals. A well‐established method to assess escape behavior is the flight initiation distance (FID), which is the distance between prey and predator at which an animal flees. Previous studies in various species throughout the animal kingdom have shown that group size, urbanization, and distance to refuge and body mass affect FID. In most species, FID increases if body mass, group size or distance to refuge decreases. However, how age and sexual dimorphism affect FID is rather unknown. Here, we assess the escape behavior and FID of the black redstart (Phoenicurus ochruros), a small turdid passerine. When approached by a human, males initiated flights later, that is allowing a closer approach than females. Males of this species are more conspicuous, and therefore, may exhibit aposematism to deter potential predators or are less fearful than females. Additionally, juveniles fled at shorter distances and fled to lower heights than adults. Lastly, concerning escape strategy, black redstarts, unless other passerine birds, fled less often into cover, but rather onto open or elevated spots. Black redstarts are especially prone to predation by ambushing predators that might hide in cover. Hence, this species most likely has a higher chance of escaping by fleeing to an open spot rather than to a potentially risky cover.     

Longevity and life history of cave bears – a review and novel data from tooth cementum and relative emergence of permanent dentition

Abstract

Longevity and other life history variables are key to understanding evolutionary processes and the biology of extinct animals. For the past 20 years, the lifespan of cave bears received an increased interest. Studies focusing on incremental lines of tooth cementum resulted in detailed mortality patterns from different localities. In this review, we summarise literature on age estimation as well as mortality of different European cave bear localities and present novel data on longevity from 94 teeth originating from 20 European localities. Additionally, the relative tooth emergence pattern of the permanent dentition is investigated under the Schultz’s rule framework of possible life history implications. For this, the known sequences of extant bear species are compared with the one of cave bears. Our results suggest that the typical duration of the life of cave bears was 19 years but data from literature show that in rare cases ages of up to 30–32 years were achieved. Additionally, we present the oldest known age for the Middle Pleistocene cave bear Ursus deningeri, 29 years. The tooth eruption pattern of cave bears exhibits a heterochronic shift that implies, under the assumption of Schulz’ rule, a slightly faster life history than closely related species.     

Biological maturation influences selection process in youth elite soccer players

This study examined the influence of birth date, salivary testosterone [sT] concentration, sexual maturity status, and general strength on the selection process of an elite Brazilian soccer club during a 12-month period, which was a 2^nd phase of a 24-month selection process. The stature, body mass, sT, sexual maturity status [Tanner scale], and hand grip strength were assessed for 143 players during 2 weeks. From these 143 players, 100 players were dismissed [DIS] and 43 players were selected to integrate the club’s under-14 squad. Following 1-year training period, the under-14 team was assembled with 9 players designated as starters [STA], and then, comparisons were conducted taking into account a group of non-starters (selected; SEL = 34 players) and STA (n = 09). The DIS, SEL, STA players, and reference population, were compared for birth distribution. A greater proportion of players was born in the first trimester in the STA [75.0%], SEL [57.1%] and DIS [50.0%] groups compared to the reference population [25.8%]. One-way ANOVA showed a higher sT for STA group [516.0 ± 129.9 pmol·L^-1], compared to SEL [415.5 ± 117.9 pmol·L^-1] and DIS groups [390.9 ± 84.9 pmol·L^-1; p = 0.003), and Kruskall-Wallis test showed a higher gonadal development for STA compared to DIS [p = 0.001]. The current findings suggest a strong influence of birth date and biological maturation on young soccer players selection process. Soccer coaches should consider these influences when making decisions about player selection of elite youth players.     

外源保幼激素对异色瓢虫卵巢发育及生殖相关基因转录水平的影响

【目的】本研究旨在明确外源保幼激素(juvenile hormone, JH)对异色瓢虫Harmonia axyridis成虫卵巢发育以及生殖信号通路中关键基因转录水平的影响。【方法】以萝卜蚜Lipaphis erysimi饲喂的异色瓢虫雌成虫为空白对照组,以点滴同体积丙酮的雌成虫为溶剂对照组,对人工饲料饲喂的羽化后第2天的雌成虫点滴不同剂量(80, 120和160 ng/头)JHⅢ1, 3, 5, 7和9 d后,解剖成虫卵巢,拍照并测量卵巢长度及其第一卵室的长度和宽度。利用qPCR分析在最适JHⅢ剂量(120 ng/头)处理后1, 5和9 d的异色瓢虫雌成虫生殖信号通路中关键基因JH受体methoprene-tolerant (Met)基因、krüppel homolog 1 (Kr-h1)基因、卵黄原蛋白(vitellogenin, Vg)基因(Vg1和Vg2)和卵黄原蛋白受体(vitellogenin receptor, VgR)基因表达水平。【结果】与溶剂对照组相比,点滴80和120 ng/头剂量JHⅢ可促进异色瓢虫成虫卵巢发育,其中120 ng/头剂量JHⅢ处理羽化后第2天雌...     

Characteristics of the Summer Hydrological Regimen and Chlorophyll Distribution in the Volga River Reservoirs

Field observations on chlorophyll content and hydrological parameters such as temperature, dissolved oxygen and conductivity profiles, Secchi disk transparency and water color were carried out at 5 reservoirs of the Mid and Lower Volga River during August 1990 and 1991. Principal Component Analysis distinguished four classes from 46 sampling points based on the hydrological regimen and phytoplankton development.     

外源保幼激素对中华通草蛉滞育解除及滞育后发育的影响

[目的]本研究旨在明确外源保幼激素(juvenile hormone,JH)在中华通草蛉Chrysoperla sinica滞育快速解除过程中的使用剂量及最佳使用时期.[方法]测定点滴不同剂量(0,5,15,25和35 μg/成虫)外源JH后中华通草蛉滞育成虫的产卵前期、产卵历期、雌虫寿命及单雌产卵量,以及15 μg/...