Embryonic and larval traits of the temperate damselfish Chromis crusma reveal important similarities with other Pomacentridae throughout the family's thermal range

Embryonic development and larval morphology of Chromis crusma was described from five nests sampled between 21 and 25 m depth in central Chile (33°S). From each nest, a set of c. 100 randomly selected eggs were hand-collected and transported in seawater to the laboratory. Subsets of c. 30 eggs per nest were maintained in 50 ml glass containers at a constant ambient temperature of c. 12°C (range 11.5–12.9°C). Egg length (L) and width (W) and larval notochordal length (L_N) were measured from photographs. Geometric morphometric analyses were performed in newly hatched and 1 week old larvae to quantify shape changes. Ellipsoid eggs had an average (mean ± SE) size of 1.12 ± 0.05 mm L and 0.67 ± 0.02 mm W, with volume being similar throughout 15 developmental stages (i.e., ellipsoid-shaped; 0.27 mm³). Planktonic larvae hatched between 5 and 11 days at 12°C and had a mean L_N of 3.13 ± 0.25 mm, a yolk sack volume of 0.03 mm³ and an oil droplet volume of 0.005 mm³. Morphological traits at hatching included: (a) lack of paired fins and jaws; (b) single medial fin fold; (c) lack of eye pigmentation; (d) yolk sac present near anterior tip; (e) melanophores distributed along ventral surface with one pair over the forehead. In order to generate an up-to-date summary of developmental traits within Pomacentridae, we reviewed literature on egg development (e.g., shape and number of oil droplets), hatching and larval traits (e.g., morphology, pigmentation patterns). Thirty-two publications accounting for 35 species were selected, where eggs, embryonic development, hatching and larval traits were found for 26, 21, 24 and 34 species, respectively. In order to evaluate potential phylogenetic and environmental relationships within the early stages of Pomacentridae, cluster analyses (Bray Curtis similarity, group average) were also performed on egg and larval traits of 22 species divided by subfamily (Stegastinae, Chrominae, Abudefdufinae, Pomacentrinae) and thermal ranges (i.e., low: 16.5°C (range: 12–21°C), medium: 24.5°C (range:21–28°C) and high: 27°C (range: 26–28°C)), suggesting that early developmental patterns can be segregated by both temperature and phylogenetic relationships.     

Effects of Aldicarb on the Behavior of Heterodera schachtii and Meloidogyne javanica

The toxic effects of sublethal concentrations ofaldicarb were studied on eggs and second-stage larvae and males of Heterodera schachtii and second-stage larvae only of Meloidogyne javanica in a quartz sand substrate. Aldicarb was more toxic to eggs of H. schachtii than to those of M. javanica. Complete suppression of hatching occurred between 0.48 and 4.8 μg/ml aldicarb for H. schachtii whereas 100% inhibition of hatch of M. javanica occurred between 4.8 and 48.0 μg/ml. M. javanica hatch was stimulated at 0.48 μg/ml aldicarb. Migration of second-stage larvae of H. schachtii and M. javanica in sand columns was inhibited under continuous exposure to 1 μg/ml aldicarb. Infection of sugarbeet and tomato seedlings by larvae was inhibited at 1 μg/ml. H. schachtii males failed to migrate toward nubile females at 0.01 μg/ml aldicarb. This was partially confirmed in a field study in which adding aldicarb to soil resulted in fewer females being fertilized.     

Parental,social and environmental factors associated with hatching failure in Florida Scrub‐Jays Aphelocoma coerulescens

Hatching failure within clutches of eggs occurs to varying degrees in many avian species. We investigated predictors of hatching failure in a population of Florida Scrub‐Jays, for which hatching success has been monitored for 15 years. We assessed whether hatching failure was related to parental traits (e.g. age, experience as a pair or body condition), lay date, social structure (e.g. number of helpers), environmental conditions, or some combination of these. We used linear mixed models and Akaike’s information criterion to determine the models that best explain observed patterns of hatching failure. The best model showed that increased hatching failure was associated with below‐average rainfall during the breeding season, and was more common for newly established breeding pairs than for pairs that had previously produced one or more clutches together. Other contributing models suggested that hatching failure was greatest for the youngest and oldest female breeders. Some aspects of our findings are consistent with conclusions drawn from other species. However, as a whole, our analyses suggest that hatching failure in the Florida Scrub‐Jay is influenced by a complex set of environmental and parental factors.     

Asynchronous population dynamics of Siberian lemmings across the Palaearctic tundra

The synchrony of Siberian lemming (Lemmus sibiricus L.) population dynamics was investigated during a ship-borne expedition along the Palaearctic tundra coast in the summer of 1994. On 12 sites along the coast from the Kola Peninsula to Wrangel Island, relative densities of lemmings were recorded using a standardised snap-trapping programme. The phase position of the lemming cycle in each of the studied populations was determined based on current density estimates, signs of previous density and the age profile of each population (ageing based on eye lens mass). In addition, dendrochronological methods were used to determine when the last peak in the density of microtine populations occurred at each site. The examined lemming populations were in different phases of the lemming cycle. Some populations were in the peak phase, as indicated by high current densities, an age profile in which older individuals were well represented, and signs of high previous density (abundant old lemming faeces). Other populations were in the decline phase, as reflected in a moderate current density, a predominance of older individuals and signs of high previous density. Populations in the low phase had an extremely low current density and showed signs of high previous density, while populations in the increase phase had a moderate current density, a predominance of younger individuals and showed signs of low previous density. The results of phase determinations based on dendrochronological methods support the findings based on lemming demography. Recent Russian studies carried out on some of the sites also agreed with our phase determination results. Thus, on a regional scale (across the whole Palaearctic tundra), the population dynamics of Siberian lemmings can be considered asynchronous. However, sites situated adjacent to each other were often phase synchronous, suggesting a more fine-grained pattern of dynamics with synchrony over distances as long as 1000 km or so, e.g. the Yamal and Taymyr Peninsulas. Received: 19 August 1998 / Accepted: 1 March 1999     

Successive microsporogenesis affects pollen aperture pattern in the tam mutant of Arabidopsis thaliana

Background and Aims

The tam (tardy asynchronous meiosis) mutant of Arabidopsis thaliana, which exhibits a modified cytokinesis with a switch from simultaneous to successive cytokinesis, was used to perform a direct test of the implication of cytokinesis in aperture-pattern ontogeny of angiosperm pollen grains. The aperture pattern corresponds to the number and arrangement of apertures (areas of the pollen wall permitting pollen tube germination) on the surface of the pollen grain.

Methods

A comparative analysis of meiosis and aperture distribution was performed in two mutant strains of arabidopsis: quartet and quartet-tam.

Key Results

While the number of apertures is not affected in the quartet-tam mutant, the arrangement of the three apertures is modified compared with the quartet, resulting in a different aperture pattern.

Conclusions

These results directly demonstrate the relationship between the type of sporocytic cytokinesis and pollen aperture-pattern ontogeny.     

柳毒蛾繁殖生物学的初步观察

【目的】为了明确柳毒蛾Leucoma salicis(Linnaeus)交配的日节律高峰,温度和不同交配持续时间处理对成虫寿命、产卵量和孵化率等繁殖生物学的影响。【方法】将新羽化的柳毒蛾成虫置于养虫笼中,观察交配的日节律高峰,并统计不同温度和不同交配持续时间处理下的成虫寿命、产卵量和孵化率。【结果】成虫在羽化当晚的后半夜凌晨开始交尾,次日晚上开始产卵。成虫交配集中在羽化翌日凌晨3:00—5:00之间,高峰为4:00。产卵高峰都出现在2日龄成虫,但是,25℃下成虫交配持续时间(9.2 h)显著短于28℃(11.8 h)。交配持续时间为30、60和300 min的处理,雌成虫平均寿命显著长于对照(对照9.2 h),雄虫仅60 min的处理显著长于对照。同时,极短的交配持续时间(30 min)显著降低雌虫的产卵量和孵化率。【结论】试验明确了成虫交配的日节律高峰,在适宜的温度范围内(25~28℃),雌雄成虫的寿命、单雌总产卵量无显著差异,交配持续时间明显影响成虫寿命、产卵量和卵孵化率。     

Egg-shell calcium and the hatching of Globodera rostochiensis

The Ca²⁺ content of Globodera rostochiensis egg-shells was investigated by X-ray microanalysis. When intact eggs were treated with 5 mM sodium 1, 2-di (2-aminoethoxy) ethane-N,N,N',N',-tetra-acetate (EGTA) only part of the egg-shell Ca²⁺ was removed. Similarly treated opened egg-shells lost almost all their Ca²⁺. We think that Ca²⁺ of intact egg-shells which is accessible to EGTA is in the outer part of the shell and that the inaccessible Ca²⁺ is in the inner lipoprotein layer. Much Ca²⁺ was removed from opened egg-shells by the hatching agents Zn²⁺, La³⁺ and decationised potato-root exudate, but none by dilute acetic acid or Mg²⁺. Hatching agents, by binding to or replacing Ca²⁺, may change lipoprotein membrane structure. Eggshells treated with potato-root exudate contained about 3 times as much Ca²⁺ as untreated shells, because the treatment makes additional binding sites available. Our results suggest that three types of Ca²⁺ -binding sites occur in the egg-shell.     

日粮添加海藻粉对种蛋孵化的影响

目的:研究日粮中添加不同比例的海藻粉对种蛋孵化的影响。方法:在相同饲养条件下,随机抽取600枚种蛋进行孵化实验,每组150枚。其中Ⅰ组为对照组的种蛋,Ⅱ、Ⅲ、Ⅳ组为试验组,分别添加不同水平(1%、3%、5%)的海藻粉的种蛋。结果:结果表明:饲料中添加适量海藻粉可以显著提高种蛋的孵化率和健雏率(P0.05)。结论:以上结果说明,饲料中添加海藻粉可提高种蛋的孵化率和健雏率,且添加5.0%海藻粉孵化效果最佳。     

The discovery of hatching and transition to feeding young by male Mountain Bluebirds

In many bird species, only females incubate the eggs, but both sexes feed nestlings. The means by which males of such species discover hatching and transition to feeding their offspring remains almost completely unexplored. Of particular interest are species with nests whose contents are concealed from view. During June and early July 2015 in the Bighorn Mountains of Wyoming, we used continuous video‐recording of nests of cavity‐nesting Mountain Bluebirds (Sialia currucoides) to document the transition to feeding young by males. We saw no evidence that females used distinct vocal or visual displays to signal hatching to males. Observing mates carrying eggshells away from, or food into, nest boxes did not appear to trigger provisioning by males. Rather, at all 24 nests observed, males did not begin feeding until they had come to nest boxes and presumably sensed the presence of hatchings directly. Individual males varied, however, in both the manner in which they inspected nest contents and the number of times they did so before starting to feed young. Although most males fully entered nest boxes where they could see, touch, hear, and possibly smell hatchlings (or eggshell parts), other males may have detected hatchlings only by sound or possibly smell while perched at a nest‐box entrance. Based on past studies of mice and doves, we suggest that, for provisioning behavior to begin, some kind of direct sensation of offspring may be necessary to activate relevant neurons in the medial preoptic area of the hypothalamus of males, an area of the brain important in parental care. Additional research is necessary to test this, and to examine the effects of factors such as hormone levels and breeding experience on the means and rapidity by which males discover hatching and transition to nestling provisioning.