Age, Growth, and Gonadal Characteristics of Adult Bighead Carp, Hypophthalmichthys nobilis, in the Lower Missouri River

Bighead carp were introduced into Arkansas in 1973 to improve water clarity in production ponds. Bighead carp subsequently escaped aquaculture facilities in the early 1980's and dispersed into the Mississippi and Missouri rivers. The first documentation of bighead carp reproduction in the Mississippi River system was in 1989. The population has increased in the Missouri River as is evident in their increased proportion in the commercial harvest since 1990. The effect of this exotic planktivore on native ecosystems of the U.S. has not been examined. Basic biological data on bighead carp Hypophthalmichthys nobilis in the Missouri River are needed to predict potential ecological problems and provide a foundation for manipulative studies. The objectives of this study were to assess age, growth, and gonadal characteristics of bighead carp in the Missouri River. Adult bighead carp in our sample varied from age 3 to age 7 and length varied from 475 to 1050mm. There was a large variation in length at age, and overall bighead carp exhibited fast growth. For example, mean back-calculated length at age 3 was 556mm. The sample was dominated by bighead carp from the 1994 year class. There was no difference in gonad development (i.e., gonadal somatic index, egg diameter) between winter and spring samples. Length of male bighead carp and GSI were not significantly correlated; however, females exhibited a positive linear relationship between length and GSI. In each ovary, egg diameter frequencies exhibited a bimodal distribution, indicating protracted spawning. Mean fecundity was 226213, with a maximum fecundity of 769964. Bighead carp in the Missouri River have similar life history characteristics to Asian and European populations. They have become well established in the Missouri River and it is likely that dispersal and population density will increase.     

槐树长珠蚧的生物学特性

槐树长珠蚧Neogreenia sophorica Wu是2004年发现于北京东城区的一种新害虫,危害槐树。在北京1年发生1代,有3个龄期,以2龄若虫过冬。营孤雌生殖。每头雌蚧平均产卵105粒,平均孵化率47.53%。1龄若虫期有扩散能力,固定后分布在树干基部1m以上,直径大于5cm的枝条的树皮下。防治的最佳时机应在1龄若虫涌散期。     

Life history and male intertroop mobility among Japanese macaques (Macaca fuscata)

Male intertroop transfer among Japanese macaques (Macaca fuscata) often coincides with the mating season. However, no necessary connection exists between mating by newly arrived males and whether they join a troop—visitors often mate, and males that join troops may show little mating success. On the other hand, intertroop transfer often coincides with major events in the developmental and social life history of males, such as the attainment of sexual maturity and full adult body size or rise in dominance rank. Thus, intertroop transfer may reflect age-specific behavioral patterns in which males maintain a position in the age-rank structure of troops, where the rank acquired in a new troop is partially determined by age.     

动物生活史进化理论研究进展

综述了生活史性状、生活史对策、权衡、适合度及进化种群统计学等动物生活史进化领域的进展。权衡是生活史性状之间相互联系的纽带,分为生理权衡与进化权衡。适合度是相对的,与个体所处的特定环境条件有关,性状进化与适合度之间关系紧密。适合度是生活史进化理论研究的焦点。探讨动物生活史对策的理论很多,影响最大的是MacArthur和Wilson提出的r对策及K对策理论。随年龄的增长,动物存活率及繁殖率逐步下降的过程,称为衰老;解释衰老的进化理论主要有突变-选择平衡假设和多效对抗假设。进化种群统计学将种群统计学应用于生活史进化研究,为探讨表型适合度的进化提供了有效的手段。将进化种群统计学、数量遗传学及特定种系效应理论进行整合,建立完整的动物生活史进化综合理论体系,是当代此领域的最大挑战。     

Analyses of growth processes of pond smelt, Hypomesus nipponensis, in Lake Ogawara, Japan, through the use of daily otolith increments

It has been reported that pond smelt, Hypomesus nipponensis, in Lake Ogawara, Japan, appear in small and large size groups during spawning despite being an annual fish. It is hypothesized that pond smelt have a bimodal life history, anadromous for large size groups and resident in the lake for small size groups. We calculated the body length and growth rate of the small and large size groups through the use of daily otolith increments and compared growth parameters between groups. In addition, the growth processes of resident fish in Lake Ogawara and anadromous fish in the adjacent sea were examined and compared with small and large size groups, respectively. We found that the two size groups diverged after 40–50 days from hatching with significant size groups present after 50 days. Through otolith increment analysis the growth processes of the small and large size groups were correlated with resident and anadromous forms respectively. These results revealed the utility of otolith increment analyses to clarify population structure of this species.     

Life history and interspecies relationships of Chirocephalus diaphanus Prévost and Tanymastix stagnalis (L.), (Crustacea,Anostraca) inhabiting a group of mountain ponds in Latium,Italy

Life histories of two coexisting Anostracan species, inhabiting a group of mountain ponds in Latium (Pantani di Forca Canapine) are described and discussed, with particular regard to hatching requirements, growth rate, fecundity and life span.Unlike previously assumed (Mura, 1985), the cysts of the two species Tanymastix stagnalis and Chirocephalus diaphanus seem to respond to the same hatching stimuli, since their nauplii coexist and can be separated by morphological differences.Significant differences recorded as to size, time in attaining sexual maturity, fecundity and life span, are in favour of a niche separation by size and by time. In particular, size differences are supposed to reflect significant differences also at filtering apparatus level, thus allowing prey selection by size.     

Life history of a lacustrine ostracod

The ostracod Cypria turneri has one generation per year in Mirror Lake, New Hampshire. Juveniles hatch in January through May and reach maturity by August. The life history of this ostracod suggests that the turnover rate of the population is low.     

Histological and morphological aspects of reproduction in the sandbar shark Carcharhinus plumbeus in the U.S. south‐eastern Atlantic Ocean and Gulf of Mexico

The reproduction of the sandbar shark Carcharhinus plumbeus in the U.S. south‐eastern Atlantic Ocean including the Gulf of Mexico was examined using a combination of histological and morphological characteristics of C. plumbeus collected through fishery‐dependent and ‐independent sampling programmes (n = 1,567). Indices of maturity were constructed using measurements of gonads, reproductive tracts and claspers, and sandbar sharks exhibited 50% maturity sizes of 140 and 148 cm fork length for males and females respectively. Gonado‐somatic indices and variation in reproductive tract condition were used to determine seasonal trends in reproduction of mature C. plumbeus. Sandbar sharks have discrete seasonal reproductive cycles in which males produce sperm from January to May with a peak in May and females develop eggs from January to May with ovulation occurring in June. Females were shown to exhibit a >2 year reproductive cycle. Embryonic development was assessed through measurements of masses and lengths of uterine contents. Gestation was 12 months, from July to the following June, with parturition in late June. This research highlights a difference from previously reported data on the periodicity of female reproduction in C. plumbeus in the U.S. south‐eastern Atlantic Ocean and Gulf of Mexico, which may have major effects on future C. plumbeus stock management.     

Brooding of pelagic-type larvae in Ophiopeza spinosa: reproduction and development in a tropical ophiodermatid brittlestar

Abstract. Ophiopeza spinosa , a small ophiodermatid ophiuroid, is locally abundant in shallow water rubble habitat at Lizard Island, northern Great Barrier Reef, Australia. This species is a protantric hermaphrodite. The switch from reproduction as a male to a female is progressive, involving a simultaneous hermaphrodite as a transitional stage. Members of O. spinosa brood their young in the respiratory bursae. Cohorts of eggs (280 μm diameter) develop synchronously in the gonad and are spawned as a group into the bursa. Despite non-pelagic development, the larvae of O. spinosa are a vitellaria type typical of broadcast-spawning ophiodermatids, providing a link to an ancestral form with a dispersive larva. The vitellaria has prominent ciliary bands and swims in the same manner as pelagic vitellaria. In vitro , the larvae developed to the juvenile stage independent of the parent. There was no evidence of extraembryonic nutrition; a proportion of the maternal provisions were retained through metamorphosis. This is the first ophiuroid known to brood a pelagic-type vitellaria larva. Juveniles appear to leave the parent at the two- to three-arm segment stage, slightly larger than the newly settled juveniles of ophiodermatids with pelagic vitellariae. The presence of functional larvae in the bursa suggests a recent switch to the incubatory life history in O. spinosa and the possibility of a reversal back to a dispersive life history. O. spinosa have the potential to both brood and broadcast their young.     

Life‐History Data in Bioindication Procedures,Using the Example of Hoverflies (Diptera,Syrphidae) in the Elbe Floodplain

This is the first study to relate syrphid life history traits to environmental variables with a multi‐trait approach. We aimed to answer two questions: 1. Do syrphid species respond to small scale changes in environmental variables in seasonally flooded grasslands in a Central European floodplain (Elbe)? 2. Can species response to environmental variables be explained by the biological characteristics of the species expressed by their life history traits? Despite their large mobility, syrphids did respond significantly to small scale changes in environmental variables (groundwater (GW) depth, cation exchange capacity, amplitude of variation of the GW‐depth). On the other hand, the biological traits of the syrphids did not sufficiently explain syrphid occurrence at the sites. Possible explanations are discussed and an outlook for further studies is given. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Costly lifetime maternal investment in killer whales

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Offspring size and parental fitness in Daphnia magna

Variation in offspring size and number has been described for a wide range of organisms. Many theoretical models predict that in a given environment, the production of one single offspring size would yield the highest parental fitness. In most planktonic cladocerans, however, offspring size has been found to increase with size and age of the mother, and as individuals of variable size often co-occur within a population, offspring of variable sizes can be produced simultaneously. In this study, I investigated the relationship between age of the mother and size of her offspring to assess at what age of the mother the optimal offspring size was produced. Optimal offspring size was defined as that size of the offspring yielding the highest parental fitness, which translates to a definition of optimal offspring size as the one having the highest juvenile fitness per unit effort put in these juveniles. I observed that the youngest females produced offspring with the highest juvenile fitness per unit effort, and hence concluded that offspring produced by these females were of optimal size. Larger offspring produced by older females were estimated to yield only 70% of the potential fitness of optimally sized offspring.     

Recent studies of dental development in Neandertals: Implications for Neandertal life histories

Did Neandertals share with modern humans their prolonged periods of growth and delayed ages of maturation? During the past five years, renewed interest in this question has produced dental studies with seemingly contradictory results. Some suggest fast dental growth, 1 , 2 while others appear to suggest a slower, modern‐human dental growth pattern. 3 , 4 Although some apparent contradictions can be reconciled, there remain questions that can be resolved only with additional data and cross‐validation of methods. Moreover, several difficulties are inherent in using dental development to gauge Neandertal life histories. Even with complete data on Neandertal dental development, questions are likely to remain about the meaning of those data with regard to understanding Neandertal life histories.     

宽礁膜的生活史

在国内首次观察描述了宽礁膜(Monostroma latissimum Wittrock)生活史各阶段的形态结构特征和发育变化,并对其单性生殖进行了周年培养和观察.大型的雌雄异体的膜状配子体成熟后,放散双鞭毛的配子,小型的球状孢子体成熟后放散四鞭毛的游孢子,其生活史是单倍体的配子体与二倍体的孢子体互相交替的异形世代交替.另外,在生活史中还发现合子和孢子囊的二分裂增殖方式,一年生配子体和二年生孢子囊等现象.未接合的雌、雄配子固着后变成球状单细胞体,室内培养后发育成成熟的单性孢子囊,并放散四鞭毛的游孢子,这些游孢子固着后,可直接发育成膜状的配子体,单性生殖也可以用来进行人工育苗.     

黄连木种子小蜂的生物学特性和发生规律

通过田间及室内饲养观察,黄连木种子小蜂EurytomaplotnikoviNikolskaya在河南省太行山区为1年发生1代,以老熟幼虫在被害果内过冬。翌年4月中旬开始化蛹,5月下旬至6月上旬为成虫羽化产卵的盛期。幼虫5月中旬开始孵化,在果内取食至8月中、下旬老熟越冬。成虫在果壳内停留4～5d,出壳后成虫寿命:雄虫3～7d,雌虫4～17d,产卵前期3.7d。平均产卵量35.4粒,卵期3～4d。幼虫共5龄,预蛹期4～5d,蛹期8～10d,蛹期发育过程中形态变化的阶段性分为4级。成虫交尾产卵的最适温度为23～25℃,化蛹、羽化较适宜的湿度为65%～70%。     

LIFE HISTORY AND THE EVOLUTION OF PARENTAL CARE

Patterns of parental care are strikingly diverse in nature, and parental care is thought to have evolved repeatedly multiple times. Surprisingly, relatively little is known about the most general conditions that lead to the origin of parental care. Here, we use a theoretical approach to explore the basic life‐history conditions (i.e., stage‐specific mortality and maturation rates, reproductive rates) that are most likely to favor the evolution of some form of parental care from a state of no care. We focus on parental care of eggs and eggs and juveniles and consider varying magnitudes of the benefits of care. Our results suggest that parental care can evolve under a range of life‐history conditions, but in general will be most strongly favored when egg death rate in the absence of care is high, juvenile survival in the absence of care is low (for the scenario in which care extends into the juvenile stage), adult death rate is relatively high, egg maturation rate is low, and the duration of the juvenile stage is relatively short. Additionally, parental care has the potential to be favored at a broad range of adult reproductive rates. The relative importance of these life‐history conditions in favoring or limiting the evolution of care depends on the magnitude of the benefits of care, the relationship between initial egg allocation and subsequent offspring survival, and whether care extends into the juvenile stage. The results of our model provide a general set of predictions regarding when we would expect parental care to evolve from a state of no care, and in conjunction with other work on the topic, will enhance our understanding of the evolutionary dynamics of parental care and facilitate comparative analyses.     

Resource partitioning in two coexisting cladocerans,Daphnia magna and Scapheloberis kingi (Anomopoda: Daphniidae), in north-eastern Algeria

Life-history traits of two coexisting cladocerans, Daphnia magna Straus and Scapheloberis kingi Sars, inhabiting a temporary pond in north-eastern Algeria were monitored in 2013 under laboratory conditions. Their life histories were compared for differences in traits such as age and size at first reproduction, size of neonates, brood size, number of broods per female, total life span and intrinsic rate of increase (r_m). Data were recorded during their entire life cycle. Daphnia magna, the larger species, could possibly be more successful in colonising temporary habitats than S. kingi because it allocates more energy to reproduction. Scapheloberis kingi, the smaller species, starts reproduction early, resulting in a smaller brood size and a shorter life span with fewer broods. Consequently, S. kingi produces a smaller number of neonates during its lifetime and has a lower r_m. In contrast, D. magna delays reproduction but produces a larger brood size and, because it is longer-lived, produces more broods and so produces a greater number of neonates and has a higher r_m over its lifetime.     

Aspects of Reproductive Biology of the Scalloped Hammerhead Shark, Sphyrna Lewini, off Northeastern Brazil

Ninety four scalloped hammerhead sharks, Sphyrna lewini (53 females and 41 males) ranging in size from 121 to 321cm total length (TL), were collected from surface gillnetters operating off northeastern Brazil and throughout the southwestern equatorial Atlantic Ocean between January and December 1996. A common regression for TL and eviscerated weight (EW) was calculated as, logEW = –11.786 + 2.889 logTL. Females and males were categorised into reproductive stages (4 and 2, respectively) according to morphological changes in their gonads. Size at sexual maturity for females was estimated to be 240cm, while males appeared to mature at between 180 and 200cm. Gravid females had between 2 and 21 embryos or pups, varying in TL from 3 to 38cm. There was no relationship between maternal length and size of litter. Copulation and parturition appear to occur outside the sampled area and possibly closer to the coast. With the exception of slightly lower uterine and ovarian fecundities, the results support the few existing data on the reproductive cycle of S. lewini in other areas.