Changes in the behavior of the female short-tailed cricket,Anurogryllus muticus (De Geer) (Orthoptera: Gryllidae) following mating

InAnurogryllus muticus females, mating stimulates burrow construction, burrow provisioning, feeding, egg production, and egg-laying. Since mating often occurs before the ovaries are fully developed, the time span between mating and oviposition is used for increased food intake and the accumulation of nutrient reserves in the fatbody. Oviposition triggers maternal care of eggs and emerging hatchlings, and blocks egg consumption. Hatchling behavior is investigated. When hatchlings eat eggs, they prefer newly laid over older, embryonic eggs.     

Survivorship and Spatial Patterns of an Urban Population of Texas Horned Lizards

Habitat fragmentation has negative consequences on threatened and endangered species by creating isolated populations. The Texas horned lizard (Phrynosoma cornutum) is experiencing population declines and localized extirpations throughout its range and has been classified as a species of greatest conservation need in Oklahoma, USA. Younger age classes have been poorly studied but may be vital to the stability of remaining populations. To address gaps in knowledge concerning subadult (hatchling and juvenile) morphometrics, survivorship, and home range sizes, we studied 2 cohorts of subadults, for 2 years each, covering their hatching and juvenile years (2016–2019). We used a combination of radio-telemetry and novel harmonic radar methodology to study a closed population of Texas horned lizards in 15 ha of native grassland at Tinker Air Force Base, Oklahoma. Population abundance for adults and juveniles was estimated as 56.5 ± 5.5 lizards and density as 7.96 lizards/ha. Our lowest estimates of survival indicated an average survival probability for the hatchling life stage of 0.285 (95% CI = 0.15–0.44), which is lower than for adults on the site. Average home range size increased from hatchling to adult life stages. Our results will have an immediate effect on the planning and assessment of ongoing headstart and management programs for Texas horned lizards. © 2021 The Authors. The Journal of Wildlife Management published by Wiley Periodicals LLC on behalf of The Wildlife Society.     

Differences in Incubation Length and Hatchling Morphology among Five Species of Oviparous Phrynocephalus Lizards （Agamidae） from China

We incubated eggs of five Phrynocephalus species （P. albolineatus, P. axillaries, P. grumgrzimailoi, P. helioscopus and P. przewalskii） at three constant temperatures （24℃, 28℃ and 32℃） to examine differences in incubation length and hatchling morphology among species and among temperature treatments. We combined data from this study with those reported previously for P. frontalis and P. versicolor to examine whether embryonic stage at laying is a causal factor for interspecific variation in incubation length, and whether the phylogenetic relationship inferred from hatchling morphology is consistent with the relationship based on mitochondrial DNA data. Mean values for incubation length differed among the five species studied herein and, in all these five species, incubation length decreased at a decreasing rate as temperature increased. In none of the five species did hatchling size （snout-vent length and body mass） and other morphological variables differ among the three temperature treatments. The seven oviparous Phrynocephalus lizards found in China differ from each other in hatchling morphology, and embryonic stage at laying is a causal factor of inter- and intra-specific variation in incubation length. The phylogenetic relationship inferred from hatchling morphology is not always consistent with the currently known relationship based on mitochondrial DNA data. Data from this study and those reported previously allow the conclusion that any Phrynocephalus species may have its unique position along the axis defined by hatchling morphology.     

Bigger is better: age class-specific survival rates in long-lived turtles increase with size

Vital rates for small, non-breeding individuals are important components of population dynamics for many species, but often individuals of these sizes are difficult to locate, capture, and track. As such, biologists frequently lack reliable estimates of juvenile survival because sample sizes and recapture rates for this life stage are low. Long-lived animals often take many years to reach sexual maturity and spend much of this time in the smaller size classes, making them sensitive to changes in survival rates. We estimated the survival rates of all size classes for the northern map turtle (Graptemys geographica) using a mark-recapture dataset with >3,500 captures from 2019–2021 and 210 nests from 2018–2021. As turtle size increased, annual survival probability increased regardless of sex. Estimated annual survival probability for turtles >18 cm long (i.e., adult females >15 years) was about 0.95, over 4 times higher than turtles that were 3 cm long (i.e., hatchlings <1 year; 0.22 annual survival probability). Although we did not observe a difference in survival probability between sexes of any size class, adult females are nearly twice the size of adult males, leading to an increased annual survival probability for females of 0.95, compared to 0.80 for males. Changes in adult survival had the greatest influence on population estimates over time, with temporary decreases, such as those due to poaching or an environmental disaster, potentially leading to unrecoverable decreases in the overall population size. Our study provides detailed survival rates for all size classes in a long-lived turtle, which are necessary to assess population stability and can be used to determine the most effective conservation or management practices.     

热环境对虎斑颈槽蛇卵孵化期、孵化成功率和孵出幼体特征的影响

用恒温（２４、２７、３０和３３Ｃ）和波动温度（平均２６．１Ｃ,范围２０．１—３２．７Ｃ）孵化虎斑颈槽蛇（Ｒｈａｂｄｏｐｈｉｓ　ｔｉｇｒｉｎｕｓ　ｌａｔｅｒａｌｉｓ）卵,检测热环境对孵化期、孵化成功率和孵出幼体的影响。孵化热环境显著影响孵化期、孵化成功率和胚胎畸形率,对孵出幼体性别无显著影响。孵化期随孵化温度升高而缩短,２４、２７、３０和３３Ｃ的平均孵化期分别为４５．０、３２．７、２７．３和２６．０ｄ,波动温度的平均孵化期为３７．９ｄ。３３Ｃ孵化成功率最低（１６．７％）,胚胎畸形率最高（１００％）。孵出幼体总性比（雌性／雄性＝０．６）不显著偏离１：１。孵出幼体的尾长显示两性异形,雄性尾长大于雌性;其它被检幼体特征无显著的两性差异。２４、２７和３０Ｃ以及波动温度孵出幼体的所有被检指标均无显著差异。３３Ｃ孵出幼体的体重和个体大小小于其它热环境中孵出的幼体,并特征性地具有较小的躯干、较大的剩余卵黄。３３Ｃ中胚胎发育的能耗显著大于其它热环境中胚胎发育的能耗。３３（‘孵出幼体的灰分含量较低,但孵出卵卵壳较重。３３Ｃ孵出幼体不能运动;其它热环境中孵出的幼体在跑道上表现良好,这些幼体的不问断运动的最大距离、每分钟运动距离和每分钟停顿次数无显著的差异。结果表明,持续将虎斑颈槽蛇卵暴露在３３Ｃ条件下不利于该种胚胎发育并可能对胚胎具有致死性影响,波动温度孵卵有利于拓宽存活孵化温度范围。     

Eggs in autumn: responses to declining incubation temperatures by the eggs of montane lizards

Facultative hatching in response to environmental cues may increase the viability of offspring, if the cue that stimulates hatching also predicts the negative consequences of delayed emergence. Declining incubation temperatures might provide such a cue for montane lizards, because eggs that fail to hatch before winter will perish in the nest. I tested this idea by incubating eggs of an alpine scincid lizard ( Bassiana duperreyi ) in the laboratory. For the first half of the incubation period the eggs were kept at nest temperatures typical of those experienced in summer in the field (daily cycle of 18 ± 7.5°C). I then transferred eggs at weekly intervals into cooler regimes (either 15 ± 7.5°C; or with daytime temperatures unchanged but dropping to 0°C overnight). Contrary to prediction, the eggs did not hatch early. However, transfer to lower temperatures caused only a relatively short delay in hatching, because of a virtual temperature-independence of developmental rates late (but not early) in incubation. Decreasing incubation temperatures also modified hatchling running speeds and post-hatching growth rates, even if the thermal decrease occurred only shortly before the usual time of hatching. These processes plausibly affect hatchling fitness in cold-climate reptiles, and might be adaptations to montane habitats. Alternatively, they may prove to be widespread in other (warmer-climate) reptile taxa, in which case no adaptive hypothesis need be proposed. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 76 , 71–77.     

两种麻蜥卵和孵出幼体的特征

研究了山地麻蜥和丽斑麻蜥实验条件下的卵及孵出幼体的特征.山地麻蜥产卵雌体的体长大于丽斑麻蜥,窝卵重小于丽斑麻蜥,但平均卵重和相对窝卵重与丽斑麻蜥相似.两种蜥蜴均通过增加卵长径和卵短径来增加卵重,但卵的外形不同,山地麻蜥卵较长.两种蜥蜴卵孵化过程中均吸水增重.相似孵化条件(波动温度、-12 kPa)下,山地麻蜥的孵化期明显比丽斑麻蜥长.山地麻蜥幼体的尾、头部大于丽斑麻蜥,但体重和SVL相似.     

Nano-tags for neonates and ocean-mediated swimming behaviours linked to rapid dispersal of hatchling sea turtles

Dispersal during juvenile life stages drives the life-history evolution and dynamics of many marine vertebrate populations. However, the movements of juvenile organisms, too small to track using conventional satellite telemetry devices, remain enigmatic. For sea turtles, this led to the paradigm of the ‘lost years'' since hatchlings disperse widely with ocean currents. Recently, advances in the miniaturization of tracking technology have permitted the application of nano-tags to track cryptic organisms. Here, the novel use of acoustic nano-tags on neonate loggerhead turtle hatchlings enabled us to witness first-hand their dispersal and behaviour during their first day at sea. We tracked hatchlings distances of up to 15 km and documented their rapid transport (up to 60 m min⁻¹) with surface current flows passing their natal areas. Tracking was complemented with laboratory observations to monitor swimming behaviours over longer periods which highlighted (i) a positive correlation between swimming activity levels and body size and (ii) population-specific swimming behaviours (e.g. nocturnal inactivity) suggesting local oceanic conditions drive the evolution of innate swimming behaviours. Knowledge of the swimming behaviours of small organisms is crucial to improve the accuracy of ocean model simulations used to predict the fate of these organisms and determine resultant population-level implications into adulthood.