增温对人工养殖东北林蛙生长曲线的影响

2009年5～9月对东北林蛙增温和正常条件下的生长情况进行了初步研究.将一龄和二龄林蛙随机分成两组,一组在大棚内增温条件下饲养,另一组在围栏中常温条件下饲养,大棚内的平均温度较围栏中提升了3.17℃.2009年9月在大棚中饲养一龄林蛙和二龄雌性林蛙体重分别达到(6.30±2.62)g和(36.55±11.79)g,较围...     

三角鲤的繁殖与生长特性

对三角鲤的年龄与生长、食性和繁殖进行了研究。三角鲤体长和体重相关 ,关系方程式为W =0 0 1 1 3 71L3 3 2 44。 3 龄以前生长较快 ,生长指标高 ,体长和体重的瞬时生长率大。其生长规律符合VonBertalanffy方程 :Lt=5 7 2 5 [1 -e-0 11717(t 2 9614 7) ];Wt=6762 0 4[1 -e-0 11717(t 2 9614 7) ]3 。生长拐点tr=6 41龄。其食性是以底栖动物为主的杂食性鱼类。性成熟年龄雌鱼为 3 龄 ,雄鱼为 2 龄 ,相对繁殖力为 5 5～ 88粒 g体重。一年多次产卵 ,产卵盛期为 4～ 5月 ,胚胎发育所需积温约为 2 3 0 0℃·h。     

锦江翘嘴鲌的繁殖生物学特征

对2015年1月至12月采集于锦江的翘嘴鲌(Culter alburnus)进行了繁殖生物学特征的研究。锦江的翘嘴鲌繁殖期集中在6~7月,属分批产卵类型。繁殖群体年龄在3+龄至6+龄之间,体长250~537 mm,体重184.9~2 587.5 g。雌雄性比1.14︰1,体表差异表现在泄殖孔和腹部膨胀程度,雌雄群体间体长-体重关系存在显著性差异(0.01P0.05)。性成熟雌鱼绝对繁殖力25 067~54 274粒,相对繁殖力24.2~36.9粒/g,平均卵径(1.1±0.3)mm。性成熟系数在1~5月份逐渐增大,6月明显上升,7月达到最高峰,8月显著下降,9~12月逐渐趋于平缓。采用Logistic方程推算了初次性成熟个体特征,雄性体长273 mm,体重192.0 g,年龄3.4龄;雌性体长311 mm,体重249.4 g,年龄4.2龄。锦江种群繁殖期与其他地理种群相近,但绝对繁殖力和相对繁殖力明显偏小。     

岷江眉山段四川华鳊的繁殖生物学资料

于2013年3月至2014年1月对岷江眉山段四川华鳊(Sinibrama taeniatus)的繁殖生物学进行了研究。四川华鳊的繁殖时间主要集中在4~5月份,最小性成熟雌性个体体长70 mm,体重7.1 g;最小性成熟雄性体长为65 mm,体重为4.5 g。四川华鳊种群性比(雌︰雄)为1.00︰1.57,主要由4个年龄组组成,其中1龄个体数量占绝对优势。性成熟系数4~5月份最大,同期丰满度最小。卵径(1.05±0.17)mm,大小分布呈单峰型,为单批产卵型鱼类。绝对繁殖力(2 734±258)粒,相对繁殖力为(236±20)粒/g,绝对繁殖力随着鱼体长、体重增长而增大。分析显示,选择适合的渔具、渔法对保护岷江眉山段四川华鳊自然种群资源十分重要。     

长江宜昌段鲢的繁殖生物学特征

2014年3月至2016年9月在长江中下游宜昌江段共收集鲢(Hypophthalmichthys molitrix)样本433尾,进行繁殖生物学研究。该江段鲢的繁殖时间为每年的5月下旬至8月上旬,以6~7月为盛产期。繁殖群体体长310~927 mm,体重600~17 090 g,由3~7龄共5个年龄组组成,3龄群体数量上占绝对优势,占繁殖群体的45.2%。雌雄性比为1.43︰1,雌雄群体间体长-体重关系存在显著性差异(0.01P0.05)。采用Logistic方程推算出初次性成熟雌性个体体长为482.3 mm,体重为2 206.7 g;初次性成熟雄性个体体长为484.0 mm,体重1 677.5 g。卵径(1.01±0.12)mm,大小分布呈单峰型,为单批产卵型鱼类。绝对繁殖力(477 662±9 631)粒,相对繁殖力为(93.38±5.92)粒/g,绝对繁殖力随着鱼体长、体重增长而增大。与其他地理种群相比较,宜昌江段鲢总体表现为卵径相对较小而繁殖力较大。     

雅鲁藏布江黑斑原鮡繁殖生物学研究

对2004-2006年采集于雅鲁藏布江拉萨河的190尾黑斑原鮡进行了繁殖生物学研究。雄性最小性成熟(精巢Ⅳ期)个体体长141.7mm,体重45.2g,性体指数1.09%,雌性最小性成熟(卵巢Ⅳ期)个体体长146.8mm,体重66.7g性体指数11.52%,相应年龄均为5龄。初次性成熟年龄(L50):♂,170.1mm相应年龄为7龄;♀,150.2mm,相应年龄5龄。通过组织切片法和GSI的周年变化分析,繁殖时间集中在5-6月,每年繁殖一次,繁殖之后的6-8月卵巢从Ⅵ期回复到Ⅲ期,9月卵巢发育到Ⅳ期越冬。卵径频率分布显示,卵巢发育类型为分批同步型,卵巢中至少存在2批卵径,每年成熟一批卵并同时产出,产卵类型为完全同步产卵。卵黏性,成熟卵卵径在2.04-3.37mm之间,平均(2.83±0.16)mm。对19尾产卵前夕(体长为151.0-210.0mm)的标本进行统计,其绝对繁殖力范围在525-2058粒之间,平均为(1244±346)粒,相对繁殖力为(14.7±5.8)粒/g。绝对繁殖力与体长呈直线正相关,表达式为F=13.624L-1187。       

黄缘盒龟的繁殖生物学

黄缘盒龟 6～ 7龄达到性成熟 ,繁殖行为主要表现为发情求偶、交配和产卵。发情交配时间为 4～5月和 9～ 1 0月 ,产卵时间为 6～ 7月 ,每只雌龟每年产卵 1窝 ,每窝 1～ 6枚。卵重一般为 ( 1 4 46± 2 2 7,n =2 5 )g ,卵的长径与短径之比为 1 88∶1 ;卵黄和蛋白的质量比为 1 2 2∶1 ;卵黄和卵壳的质量比为 3 1 2∶1。多数受精卵于产出 2 4～ 48h后形成受精环带     

华南地区外来鱼类革胡子鲶的繁殖生物学

2011年8月—2015年8月在华南地区主要河流收集255尾革胡子鲶(Clarias gariepinus)样本,对其繁殖生物学特征进行研究。结果表明:革胡子鲶繁殖季节为5—8月,繁殖旺季为6—7月,卵径分布呈现明显的多峰型;成熟系数与脂肪系数和肥满度的周年变化存在相反的趋势;绝对繁殖力为2850~605720粒,均值234232±175498粒,与体长、体重和年龄呈正相关;相对繁殖力为20~445粒·g~(-1),均值165±99粒·g~(-1),随体长、体重和年龄的增加呈先增加后趋于稳定趋势;绝对繁殖力和相对繁殖力均大于常见的鲶科鱼类。繁殖群体性比为1∶1.12,符合1∶1比例;雌、雄鱼最小性成熟个体均为1龄,Ⅳ期性腺;雌鱼体长174 mm,体重119.5 g,成熟系数为8.50%;雄鱼体长205 mm,体重116.2 g,成熟系数为0.45%;繁殖群体以1和2龄鱼为主,分别占繁殖群体总数的42.28%和51.68%,以补充群体占优势;华南地区革胡子鲶野生种群具有分批产卵、相对繁殖力高、卵径小、性成熟年龄低的特征,有利于其迅速建立稳定的种群,应加强对革胡子鲶野生种群动态的监测力度,并进一步采取防控措施。     

塔里木河叶尔羌高原鳅繁殖生物学研究

2010年7月至2011年12月,在塔里木河阿拉尔段采集叶尔羌高原鳅Triplophysa (Hedinichthys) yar-kandensis (Day)940尾(除性别未辨个体外)用于繁殖生物学研究。种群雌雄比为0.85︰1,最小性成熟,雌性个体体长为8.2 cm,体重为7.4 g,年龄为3龄;雄性个体体长为6.5 cm,体重为3.4 g,年龄为2龄。叶尔羌高原鳅卵径分布呈单峰形,推测应属于同步产卵类型。计算了88尾Ⅳ-Ⅴ期雌鱼的怀卵量,其体长范围30-195 mm,体重范围3.59-114.04 g,绝对繁殖力为1101-56320(9944±5487)粒,相对繁殖力为824-1140(982±158);塔里木河阿拉尔段叶尔羌高原鳅种群繁殖力(Fp)为403.46万粒。     

中国林蛙卵人工孵化试验

中国林蛙 (Rana chinensis)是我国重要的经济蛙类之一。近年来 ,由于人们的生态经济意识不强 ,森林环境破坏严重 ,以及滥捕乱捉 ,使得中国林蛙种群数量急剧下降。但在一些地区 ,由于加强对中国林蛙的管护 ,大力发展林蛙人工养殖业 ,使之成为当地经济发展的一项重要支柱产业。由于林蛙人工饲养刚刚起步 ,饲养经验不完善 ,一些问题有待深入研究。如在自然条件下母蛙产卵时期 (4月上旬 )大致相同 ,但据以往观察 ,幼蛙出池时间却有很大差别 ,而出池时间的早晚表现在秋季回归时的体重差别较大 (约 1倍体重 )。因此缩短卵孵化时间 ,促使幼蛙提早…     

Interrelationship between food availability, fat body, and ovarian cycles in the frog, Rana tigrina, with a discussion on the role of fat body in anuran reproduction

Long-term experiments were conducted to study the progression of vitellogenic cycles in Rana tigrina (an annual breeder) having different foraging backgrounds and held under conditions of weekly or daily food supply and in presence or absence of abdominal fat bodies. They were autopsied in June to assess fecundity. In nature an adult R. tigrina produces on an average 4,000 eggs/100 g body mass (b.m.) And spawns in June-July following monsoon rains. Weekly feeding from July to next breeding season, June resulted in a significant decrease in both fecundity (1700 eggs/100 g body b.m.) And mean size of eggs, compared to well-fed or wild-caught frogs. The abdominal fat bodies were barely seen in frogs fed weekly throughout, whereas in frogs fed weekly from July-December but daily from January onwards, the fat bodies became noticeable (1% of b.m.) And number and mean size of eggs increased significantly over those fed weekly throughout. Frogs captured in January possessed enlarged fat bodies (5% of b.m.), depicting a good foraging history. Maintenance of these frogs on a weekly feeding regimen led to an exhaustion of fat stores. They produced less number of eggs (2, 000/100 g b.m.) As compared to wild frogs but of normal size, whereas daily feeding slowed down a depletion of fat body mass and also significantly increased fecundity (3,000/100 g b.m.) Over the weekly fed individuals. Sham operation or fat body ablation in October or February had no significant effect on total fecundity per se (3,000-3,500 eggs/100 g b.m.) Compared to that of wild-caught frogs. However, eggs were significantly smaller due to fat body ablation despite daily feeding. The study shows that food abundance/fat bodies influence egg size and number in R. tigrina and that a direct or indirect functional relationship exists between fat body and ovarian cycles that are characteristically inverse to each other. J. Exp. Zool. 286:487-493, 2000.     

Effects of available cover and feeding schedule on the behavior and growth of the juvenile African clawed frog (Xenopus laevis)

Though the African clawed frog (Xenopus laevis) is the most commonly used amphibian in biological research, there are no standard protocols for the husbandry of this species. With the goal of developing optimal conditions for raising these frogs, the authors assessed the effects of available cover and feeding schedule on post-metamorphic growth and behavior of juvenile X. laevis. Frogs, which were housed four per tank, had access to varying numbers of shelters (zero, two or four) and were fed either daily or episodically (three times per week) over a period of 6 months. Though X. laevis growth was not influenced by the availability of cover, frogs that were fed daily grew larger than frogs that were fed episodically. Additionally, frogs that were fed daily and had no access to cover were most likely to exhibit foraging behavior when disturbed. These results suggest that feeding frogs daily will promote growth and fecundity. Furthermore, although labs often provide frogs with hiding places, such cover does not enhance X. laevis growth.     

Macroecology and extinction risk correlates of frogs

Aim  Our aim was to test whether extinction risk of frog species could be predicted from their body size, fecundity or geographical range size. Because small geographical range size is a correlate of extinction risk in many taxa, we also tested hypotheses about correlates of range size in frogs.
Location  Global.
Methods  Using a large comparative data set ( n  = 527 species) compiled from the literature, we performed bivariate and multiple regressions through the origin of independent contrasts to test proposed macroecological patterns and correlates of extinction risk in frogs. We also created minimum adequate models to predict snout–vent length, clutch size, geographical range size and IUCN Red List status in frogs. Parallel non-phylogenetic analyses were also conducted. We verified the results of the phylogenetic analyses using gridded data accounting for spatial autocorrelation.
Results  The most threatened frog species tend to have small geographical ranges, although the relationship between range and extinction risk is not linear. In addition, tropical frogs with small clutches have the smallest ranges. Clutch size was strongly positively correlated with geographical range size ( r ² = 0.22) and body size ( r ² = 0.28).
Main conclusions  Our results suggest that body size and fecundity only affect extinction risk indirectly through their effect on geographical range size. Thus, although large frogs with small clutches tend to be endangered, there is no comparative evidence that this relationship is direct. If correct, this inference has consequences for conservation strategy: it would be inefficient to allocate conservation resources on the basis of low fecundity or large body size; instead it would be better to protect areas that contain many frog species with small geographical ranges.     

Cricket frogs maintain body hydration and temperature near levels allowing maximum jump performance

One goal of this study was to determine the combination of hydration and temperature in the northern cricket frog Acris crepitans that allowed maximum jump distance in the laboratory. Second, environmental variables in the field were measured to determine the best predictor(s) of mean body temperature and hydration and to determine whether frogs maintain levels of temperature and hydration yielding maximum jump distance. Laboratory data revealed that hydration and the hydration-temperature interaction significantly affected jump performance. Frogs at 95% and 85% hydration jumped significantly better than frogs at 75% hydration, but frogs at 95% hydration at 15 degrees C jumped significantly poorer than those at 95% hydration at 30 degrees C. Animals at 85% hydration at 30 degrees C and 85% hydration at 15 degrees C jumped just as well as those at 95% hydration at 30 degrees C. Mean body temperature of 55 frogs in the field was 28.0 degrees C, and hydration was 97.4%. Sky condition (sunny, cloudy, or partly cloudy) was the best predictor of frog hydration, and air temperature was the best predictor of frog body temperature. Cricket frogs in the field maintain a hydration and temperature near those found to yield maximum jump distances in laboratory trials. This may be a behavioral adaptation to allow maximum jump distance during predator avoidance.     

Climatic oscillations triggered post-Messinian speciation of Western Palearctic brown frogs (Amphibia,Ranidae)

Oscillating glacial cycles over the past 2.4 million years are proposed to have had a major impact on the diversity of contemporary species communities. We used mitochondrial and nuclear DNA sequence data to infer phylogenetic relationships within Western Palearctic brown frogs and to test the influence of Pliocene and Pleistocene climatic changes on their evolution. We sequenced 1976bp of the mitochondrial genes 16S rRNA and cytochrome b and of the nuclear rhodopsin gene for all current species and subspecies. Based on an established allozyme clock for Western Palearctic water frogs and substitution rate constancy among water frogs and brown frogs, we calibrated a molecular clock for 1425bp of the 16S and rhodopsin genes. We applied this clock to date speciation events among brown frogs. Western Palearctic brown frogs underwent a basal post-Messinian radiation about 4 million years ago (mya) into five major clades: three monotypic lineages (Rana dalmatina, Rana latastei, Rana graeca), an Anatolian lineage, and a lineage comprising Rana italica, Rana arvalis, and all Iberian taxa. Polytypic lineages radiated further in concordance with the onset of climatic oscillations ca. 3.2, 2.0, and 1.0-0.6 mya, respectively. The dated fossil record corroborates our paleobiogeographic scenario. We conclude that drastic climatic changes followed by successive temperature oscillations "trapped" most brown frog species in their southern European glacial refugia with enough time to speciate. Substantial dispersal was only possible during extensive interglacial periods of a constant subtropical climate.     

Weight loss,reproductive output,and the cost of reproduction in the common frog,Rana temporaria

Summary The consequences of reproduction for body weight, growth and survival were studied in a Swiss population of the explosive breeder, Rana temporaria. Males and females continuously loss weight in the range of 0.5% of total body weight per day from the breeding migration throughout May. Females also lost about 33% (1983) and 29% (1984) due to spawning. In addition to this significant year-to-year variation, there was also considerable individual variation in reproductive output. Skeletochronological techniques indicated that breeding male or female frogs experienced a growth reduction of several millimeters relative to non-breeding frogs of the same body size. There was no relationship between an individual female's reproductive output in consecutive years or with her subsequent growth or survival. It was concluded that weight loss is caused by a seasonally elevated metabolism in combination with a lack of feeding and represents a basic energetic cost of reproduction, resulting in lowered growth. Individual variation in relative reproductive output is mostly environmentally induced and is not an expression of different reproductive strategies. This may explain the lack of trade-offs that are predicted by the cost-of-reproduction-hypothesis.     

Determination of age, longevity and age at reproduction of the frogMicrohyla ornata by skeletochronology

Skeletochronological estimation of age, longevity, age at sexual maturity and breeding of Microhyla ornata was done. Frogs (n=62) were collected locally in August (rainy season) 1997 and brought to the laboratory. Body mass and snout-vent-length (SVL) of each frog was recorded; the 4th toe of both the hind limbs was clipped under anaesthesia, fixed in 10% formalin, demineralized in 5% nitric acid and processed for histology. Limb bones (femur, humerus, tibiofibula and radioulna) of 6 large sized frogs were also processed for skeletochronology in order to study the rate of resorption. Gonads of 25 frogs (belonging to different body size ranges) were processed for histology in order to ascertain the gametogenic status of individual frogs. One to four growth rings consisting of growth zones and lines of arrested growth (LAGs) were noticed in frogs of different body sizes; the number of LAGs remained identical in all the limb bones and phalanges in 5 out of 6 frogs. Back calculation indicated that the resorption rate is very low in this frog. Male frogs possessed sperm bundles in seminiferous tubules in the 1st year, while females showed yolky follicles in the ovary in the 2nd year. Frogs found in amplexus were 3 5 years old. The results suggest that this frog may live for a maximum of 5 years in the natural population.     

Observations on the biology of the perch, Perca fluviatilis, in the River Stour, Dorset

SUMMARY. Opercular bones from 323 perch from the River Stour were used for age and back-calculated growth determinations. Annuli were formed during May at the beginning of the growth period. Growth was minimal from October to April. Female perch grew faster than males, and the growth rates of both sexes were higher than those observed in most other European waters. Spawning occurred during late April and early May; male gonads began development in August and had attained their maximum weight in September, but the ovaries developed gradually from August until April. Immature perch had an annual cycle of condition with a maximum in June-July and a minimum in December-January. The condition of mature males and females was affected by the gonad cycle. The fecundity of Stour perch is expressed by the formula: log egg number = 2.40 log length (mm) - 1.34.
Approximately 25% of males were mature at age I and all were mature at age II, whereas most females did not spawn until age III. Ephemeroptera nymphs and minnow fry constituted the bulk of the diet of 0-group perch; Ephemeroptera nymphs, minnow fry and Corixidae were the most numerous items in I group perch, whereas older perch contained Corixidae and a wider range of fish prey species, although minnows were the most numerous of these.     

Insular shifts in body size of rice frogs in the Zhoushan Archipelago, China

1. Differences in body size between mainland and island populations have been reported for reptiles, birds and mammals. Despite widespread recognition of insular shifts in body size in these taxa, there have been no reports of such body size shifts in amphibians. 2. We provide the first evidence of an insular shift in body size for an amphibian species, the rice frog Rana limnocharis. We found significant increases in body size of rice frogs on most sampled islands in the Zhoushan archipelago when compared with neighbouring mainland China. 3. Large body size in rice frogs on islands was significantly related to increased population density, in both breeding and non-breeding seasons. Increases in rice frog density were significantly related to higher resource availability on islands. Increased resource availability on islands has led to higher carrying capacities, which has subsequently facilitated higher densities and individual growth rates, resulting in larger body size in rice frogs. We also suggest that large body size has evolved on islands, as larger individuals are competitively superior under conditions of harsh intraspecific competition at high densities. 4. Increases in body size in rice frogs were not related to several factors that have been implicated previously in insular shifts in body size in other taxa. We found no significant relationships between body size of rice frogs and prey size, number of larger or smaller frog species, island area or distance of islands from the mainland. 5. Our findings contribute to the formation of a broad, repeatable ecological generality for insular shifts in body size across a range of terrestrial vertebrate taxa, and provide support for recent theoretical work concerning the importance of resource availability for insular shifts in body size.     

Condition-dependent reproductive effort in frogs infected by a widespread pathogen

To minimize the negative effects of an infection on fitness, hosts can respond adaptively by altering their reproductive effort or by adjusting their timing of reproduction. We studied effects of the pathogenic fungus Batrachochytrium dendrobatidis on the probability of calling in a stream-breeding rainforest frog (Litoria rheocola). In uninfected frogs, calling probability was relatively constant across seasons and body conditions, but in infected frogs, calling probability differed among seasons (lowest in winter, highest in summer) and was strongly and positively related to body condition. Infected frogs in poor condition were up to 40% less likely to call than uninfected frogs, whereas infected frogs in good condition were up to 30% more likely to call than uninfected frogs. Our results suggest that frogs employed a pre-existing, plastic, life-history strategy in response to infection, which may have complex evolutionary implications. If infected males in good condition reproduce at rates equal to or greater than those of uninfected males, selection on factors affecting disease susceptibility may be minimal. However, because reproductive effort in infected males is positively related to body condition, there may be selection on mechanisms that limit the negative effects of infections on hosts.