Effects of adoption of freshwater residency on life-history ecology of terapontid grunters

1. While fish reproduction has played a critical role in development of life-history theory, the collective effects of a marine-to-freshwater invasion on a clade's reproductive ecology have rarely been explored in a phylogenetic context. We analysed and compared a range of quantitative and qualitative components of reproductive ecology in the Australasian terapontid fishes, a family distributed widely across marine, estuarine and freshwater habitats in the Indo-Pacific region. We specifically tested hypotheses that life-history strategies such as larger egg sizes and reduced fecundities are a key characteristic of freshwater species in comparison with their close marine relatives, and also fit a range of currently available evolutionary models describing the processes of ecomorphological and macrohabitat-related diversification.
2. Using recently developed phylogenetic comparative methods, differences in several quantitative reproductive traits were evident between marine and freshwater species, with reductions in average fecundity and increases in average egg size specifically characterising freshwater species. Evolutionary modelling of major trait axes, as well as specific traits across the family, highlighted significant increases in rates of evolutionary diversification across both freshwater lineages and within freshwater subclades. Modelling also supported the evolution of distinctive morpho-ecotype optima between marine and freshwater species over simpler models of random-walk evolution or single morphological optima.
3. Review of life-history behaviour identified environmental stimuli related to photoperiod, temperature, and lunar-tidal cycles (and possibly combinations thereof) as playing an important role in stimulating spawning behaviour in most marine–euryhaline species. While some of these variables (temperature and photoperiod) continue to play an important role in some freshwater species, flow regime, particularly streamflow increases, appear more important in stimulating spawning responses, underlining the role of flow regime emerging as a master variable shaping evolutionary trajectories in freshwater clades.
4. In this review and meta-analysis, we document that adaptation to an entirely freshwater existence has catalysed significant, and in several cases, relatively rapid adaptive evolution to very different life-history strategies within freshwater species. The invasion of freshwaters has had profound impacts on the trajectory of terapontid life-history evolution, driving significant changes in a range of traits relating to fecundity, egg size, spawning stimuli, and spawning substratum. Collective results suggest a distinct adaptive landscape difference between marine and freshwaters. Terapontids can provide a useful model for assessing the consistency of these outcomes with other freshwater-invading groups.

     

First report of fossil turtle eggshell west of the Colorado Plateau

The first fossil turtle eggshell from North America west of the Colorado Plateau (UCMP 218504) is described, adding to the growing global record of chelonian eggshell. Ten blocks of mudstone were collected from the Upper Miocene (Clarendonian) Orinda Formation, Contra Costa County, California, during the excavation of the Caldecott Tunnel Fourth Bore. They contain rigid eggshell averaging 500 μm in thickness. Closely packed shell units with a height/width ratio of 2:1 are composed of radiating, acicular crystals originating from a basal core, a set of characters that support the identification of the eggshell as chelonian, and further as testudinoid. Egg diameter is estimated at between 34.2 and 42.4 mm based on shell curvature. Adult carapace length is estimated to be 70.7 cm, a size similar to fossils of Hesperotestudo known from California and present in the Orinda Formation. UCMP 218504 greatly extends the geographic record of turtle fossil eggshell and adds to the limited number of mid-Neogene eggs. It also provides evidence for a warm climate in Miocene California and demonstrates the south-eastern contraction of conditions appropriate for tortoise reproduction during the last 10 million years.     

The presence of white eggs in the monitoring of Aedes albopictus ( Diptera: Culicidae) by ovitraps

Using international trading and passive transportation routes, the Asian tiger mosquito, Aedes albopictus (Skuse, 1894), has colonized Europe. While the most common tool to monitor the presence of the mosquito is the ovitrap, other kinds of eggs are occasionally found in the traps as well. Most of the eggs are easy to distinguish, however, some white‐yellow eggs have a similar shape and size to those of the tiger mosquito and are often falsely identified as freshly laid tiger mosquito eggs. We have shown that these eggs had been laid by Psychoda alternata Say, 1824, and the misinterpretation may cause large errors in calculating density and patterns of Ae. albopictus. To avoid mistakes, a microscopic observation should be done at least 48 h after collecting the sample to permit Ae. albopictus eggs to darken.     

Acute toxic effects of 8‐epidiosbulbin E,a 19‐norclerodane diterpene from yam Dioscorea antaly,on medaka Oryzias latipes embryos

The fractionation of an aqueous extract of yam Dioscorea antaly from Madagascar led to the isolation of terpenoids and flavonoids. Compounds were identified on the basis of modern mass spectrometry and two‐dimensional nuclear magnetic resonance (2D‐NMR). Toxicological effects of the most abundant isolated compound, 8‐epidiosbulbin E were studied on medaka Oryzias latipes embryo‐larval development. The lethal concentration (killing 50%; LC₅₀) to embryos treated 24 h before hatching and for 3 days after hatching was estimated to be 0·56 mg ml^?1 (P< 0·05). No mortality was observed with O. latipes larvae exposed after hatching until day 4. Anatomo‐pathological studies of embryos exposed to 0·56 mg ml^?1 showed development anomalies of the central nervous system, liver, muscle and intestine. The present data thus extend the model of O. latipes embryos as a useful animal model to analyse the effects of food toxins.     

An individual-based model for predicting the emergence period of sea trout fry in a Lake District stream

The objective of this study was to predict interannual fluctuations in the emergence period of sea trout fry, using models developed from field data for 70 excavated redds, and laboratory data on egg and alevin development at 30 constant temperatures (range 1·5–10·5° C with 100 naturally fertilized eggs at each temperature). Egg weight and numbers per redd both increased with female length; a power function described the relationship. Early spawners were the largest females laying the largest and most numerous eggs, whilst late spawners were the smallest females laying the smallest and least numerous eggs; middle spawners being intermediate between these two extremes. Mean values for egg weight and numbers of eggs per redd were obtained for these three groups. Hatching and emergence times in the laboratory decreased with increasing temperature. Of five models tested for hatching time, the best fit was provided by a three-parameter hyperbolic model which formed the asis of the individual-based model used to predict egg hatching and fry emergence. Model development was described in detail and the final equations predicted the times taken for 5, 50 and 95% of the fry to emerge, and hence the period over which 90% of the fry emerged. Analogous models were obtained for egg hatching. All models were excellent fits to the laboratory data. Hatching times for eggs kept in perforated boxes in the stream were almost identical to those kept at similar mean temperatures in the laboratory. Model predictions of fry emergence times were validated by field data for 8 years (1967–1971, 1974, 1975, 1980). The chief objective was therefore fulfilled, and predictions for the 30-year study (1967–1996) revealed a large variation in the timing of emergence (extremes: 11 March–4 April 1989, 15–20 May 1979). Most of the variation in median emergence date was due to variations in water temperature, with spawning dates as a secondary factor; the latter, however, had a greater effect on the length of the emergence period.     

中山市家口红心鸡蛋色素物质的提取研究

探讨了中山市三乡镇特产家口红心鸡蛋中色素物质的提取。结果表明，三乡特产家口红心鸡蛋色素物质呈现类胡萝卜素的特征色谱，故其色素中主要成分为类胡萝卜素物质。利用正交试验结合分析与成本，以冻干天然红心鸡蛋蛋黄为原料的提取最优条件为：以石油醚：丙酮=1：2为提取溶剂，温度室温，每次提取时间60min，提取3次，料液比为1：6，可以获得最佳提取效果。     

Polar localization of plasma membrane Ca2+/Mg2+ ATPase correlates with the pattern of steady ionic currents in eggs ofLymnaea stagnalis andBithynia tentaculata (Mollusca)

Summary During extrusion of the first polar body in eggs ofLymnaea stagnalis andBithynia tentaculata a localized Ca²⁺ /Mg²⁺ ATPase activity was detected, using Ando's enzyme-cytochemical method for electron microscopy [Ando et al. (1981) Acta Histochem Cytochem 14:705–726]. The enzyme activity was distributed in a polar fashion, along the cytoplasmic face of the plasma membrane. In the eggs ofLymnaea it was found only in the vegetal hemisphere, whereas inBithynia eggs it was localized both in the vegetal hemisphere and at the animal pole. This pattern of enzyme activity corresponds to the polar pattern of transcellular ionic currents measured with the vibrating probe, which we showed to be partially carried or regulated by calcium [Zivkovic and Dohmen (1989) Biol Bull (Woods Hole) 176 (Suppl):103–109]. The characteristics of the ATPase were studied using a variety of approaches such as ion and substrate depletions and substitutions, addition of specific inhibitors of ATPase activity, treatment with EDTA/EGTA and electron energy-loss spectrometry. The results indicate that, inLymnaea, there are at least two enzymatic entities. The first one is a Ca²⁺ /Mg²⁺ ATPase localized along the membrane and in the cortex of the vegetal hemisphere. The second one is a Ca²⁺-stimulated ATPase (calcium pump of the plasma membrane) localized in a small region of the membrane at the vegetal pole. We speculate that in the eggs ofLymnaea andBithynia a functional relationship exists between the plasma-membrane-associated ATPase activity and the transcellular ionic currents measured in the same region.     

Reproduction Peculiarities of Plain Sculpin Myoxocephalus jaokin Peter the Great Bay, Sea of Japan

We performed observations in the spawning grounds of the plain sculpin. We found that the spawning of this species in Peter the Great Bay begins in December and takes place along the coast. The egg clutches are guarded by the males.     

The value of chorionic structure and size in the diagnosis of blowfly eggs

Chorionic structure and size can be of great value in the identification of the eggs of British blowflies of forensic importance. The most useful features are the shape and structure of the plastronic area between the hatching pleats. Correct identification of the eggs of the species considered here would be of use in forensic investigations, not only in Britain, but also in the wide area of the Holarctic region.