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.     

Life history characteristics of Daphnia magna clones differing in phototactic behaviour

In an analysis of a life table experiment involving positively, intermediately and negatively phototactic Daphnia magna clones, life history traits such as the average duration of the adult instar, neonate and adult body size were found to be correlated with phototactic behaviour. The size of the eggs and neonates was positively correlated with adult body size, and with egg development time. Adult body size was positively correlated with the size of the second and subsequent clutches. I argue that the intrinsic positive correlation between offspring size and egg development time is a key factor structuring the differences in life history patterns observed between the positively and intermediately phototactic Daphnia genotypes, and that the two life history patterns are to be considered alternatives suited for different environmental conditions (e.g. habitats with and without strong predation pressure on adults).     

Life history characteristics of Brachionus plicatilis (rotifera) fed different algae

A detailed study of the life history of the rotifer Brachionus plicatilis was done at 20 °C, 20 ppt salinity, and 90 mg C 1^–1 food concentration. Rotifers were grown individually in culture plate wells (150 µl culture volume) and fed Isochrysis galbana Tahiti, Tetraselmis sp., Nannochloris atomus, or a l : 1 mixture (weight) of two of the algae. Observations were made every 2–8 hr and rotifers were sized and transferred to new food daily. A total of 19 different parameters were compared. Rotifers fed Isochrysis averaged 21 offspring per female, a 6.7 day reproductive period, a lifespan of 10.5 days and a mean length of 234 µm. After Isochrysis, the foods giving the highest growth, survival, and reproduction in decreasing order were Isochrysis + Nannochloris, Nannochloris, Isochrysis + Tetraselmis, Tetraselmis + Nannochloris, and Tetraselmis. Although the small volume culture system used in this study seems appropriate for studying life history of B. plicatilis, the results cannot always be directly applied to larger cultures.     

Life history characteristics ofPolystichum tripteron with special reference to its leaf venation

An intra-species comparison of the life history of various populations ofPolystichum tripteron was undertaken in Hokkaido and Honshu in Japan with respect to some leaf-size characters and fertility during sporophyte development. The developmental process of sporophytes was quantitatively estimated by counting the number of venation (NV: number of midrib branches of the leaf). The mean NV of the fertile leaves decreased slightly with increasing altitude on Mt. Teine near Sapporo and with increasing latitudes from Honshu to Hokkaido. The blade length was longer at any NV in Hokkaido populations than in those of southern Honshu. Longer blade (BL) and pinna length (PL) and lesser number of pinnules of the lowest pinna (NPLP) versus NV were observed in leaf populations from Hokkaido than in those from southern Honshu. The maximum values of lowest pinna length (LPL), NV, number of costa branches (NVLP) and number of pinnule (NPLP) were larger in southern Honshu than in Hokkaido. In the course of leaf-shape formation represented by the ratio of PL to BL versus NV, the Kyoto population seemed to be more differentiated into long-lanceolate fronds than did the Hokkaido population. Initiation of fertility in the sporophyte development and the maximum NV seemed to decrease with increasing altitudes and latitudes in Japan. Contribution No. 2885 from the Institute of Low Temperature Science, Hokkaido University.     

Life history characteristics and recruitment of fish under the effect of different hydrological regimes in a tropical floodplain

With the aim to analyze intra- and interspecific variation in the life history characteristics and recruitment pattern of six fish species, samples were conducted in two different hydrological regime areas of Pantanal (synchronous/Norther and asynchronous/Southern regions - high temperatures and rainfalls are and are not coincident with the flooding period, respectively). In both regions, fish were sampled using sieve net and dragnet along the river and marginal lakes. In the synchronous regime (Cuiabá River), the combined data collected between the years 2005 and 2010 were utilized. In the asynchronous regime (Paraguay River), the collections were made between 2009 and 2011. Length frequency data were used in the FISAT program to estimate the parameters. Four species, in the synchronous regime, reached trend to longer values for the asymptotic length values (L∞) and trend to lower values in growth taxa (k) and mortality (Z), but the outcomes did not demonstrate significant intraspecific variation for L∞ and Z by length classes between the hydrologic regimes (except for Moenkhausia dichroura). The recruitment pattern did not show intra- and interspecific variation between the hydrological regimes, with long period of recruitment and greater pulse for all species between June and August. Thus, the correlation of species recruitment with river level in the asynchronous regime follows the flood pulse concept, where the flooding pulse is the main driving force for production of animal and plant biomass. In contrast, the pattern of recruitment in the synchronous regime follows the hypothesis of the low flow recruitment, where the recruitment is not influenced by flooding, despite the period of high temperature and rainfall being coincident with the period of flooding.     

Life history traits of a European Messor harvester ant

We present life history traits of a Central European harvester ant, Messor cf. structor, determined by gyne and male dissections, behavioural assays, standardised brood photography and laboratory rearing of brood. Messor cf. structor is polygynous and builds up unicolonial populations. Sexuals develop from hibernated larvae in a univoltine cycle and become adult from late summer to late autumn. Neither intra- nor extranidal mating was observed in autumn, even though gynes and males were mature. In spring, after hibernation, intranidal mating without swarming flight took place, even though the flight muscles of alate sexuals were still fully developed. Received 3 March 2005; revised 4 May 2005; accepted 9 May 2005.     

Life history adaptation of Tanymastix stagnalis (Crustacea,Branchiopoda) to habitat characteristics

Life histories of two populations of Tanymastix stagnalisfrom sites in central Italy, differing in climate and altitude above sea level, were compared to obtain information on the tolerance limits of this species.Temperature was the main factor affecting the biology of Tanymastix stagnalis. Significant differences in growth patterns occurred at different sites. A colder climate induced delayed hatching, slower differentiation and maturation, but a longer life span in the mountain population (Forca Canapine) than in the plain (Fosso dei Mergani).Both populations exhibited an initial fluctuating sex ratio, which later became female biased, a pattern which could be the consequence of adaptation to the unstable nature of the biotopes studied.     

Life history characteristics of tule perch (Hysterocarpus traski) populations in contrasting environments

Synopsis The life history characteristics of tule perch were compared within and among populations in three drainages with substantially different environmental conditions. Within populations there were, in general, substantial increases in brood size, size of young, brood weight, and gonadal-somatic index (GSI) with age and with size of female. In at least one population there was a trade-off between the number and size of young produced. However, in a lake where individual growth was very slow, brood weight, GSI, and other life history characters showed decreasing trends with age. Among populations in isolated drainages, female length at first reproduction and longevity varied directly and mean brood size varied inversely with environmental predictability. Morphological and geological evidence and some comparative litter characteristics suggest that life history differences among populations in isolated drainages are in part genetic.     

Life history characteristics of the protogynous parrotfish Calotomus japonicus from northwest Kyushu, Japan

In this study, we examined the life history characteristics of the parrotfish Calotomus japonicus, using individuals collected between May 2003 and May 2008 off the Nagasaki Peninsula in northwest Kyushu, Japan. Age determinations were performed using scales. Marginal increment analysis revealed that growth rings were formed annually around July. Growth in both sexes was fitted to the von Bertalanffy growth function (L _∞ = 513, k = 0.28, t ₀ = 0.03, where L _∞ is the theoretical asymptotic total length in mm, k is the growth rate coefficient and t ₀ is the theoretical time at zero length). Observed maximum age for both sexes was 8 years. We also characterized the reproductive biology of this species based on a gonadosomatic index and histological examinations of the gonads. The spawning season extends from July to October, with peak spawning activity occurring during July and August. Fish reach sexual maturity by the second year of life. Females are assumed to be multiple spawners, since we observed specimens with postovulatory follicles in ovaries containing either yolk globule oocytes or migratory nucleus oocytes. All males had secondary testes, which were characterized by the presence of an ovarian lumen structure and sperm sinuses in the gonadal wall. This indicates that all males, irrespective of whether they were initial or terminal phase males, had undergone a sexual transition. Sex change appears to occur during the spawning season, and thereafter sex-changed males are able to fertilize female eggs throughout the remainder of the current spawning season.     

Life history adaptations of Gasterosteus aculeatus in a Mediterranean wetland

Synopsis The life cycle of leiurus-type Gasterosteus aculeatus occurring in a Mediterranean coastal wetland is described. Fish have a low number of lateral plates, short spines and marked sexual dimorphism in size. The life cycle is strictly annual, adults dying shortly after breeding. Adult fish migrate into seasonally-flooded freshwater marshes to breed, and the young migrate back to brackish water to pass the summer and autumn. Breeding occurs in March at water temperatures of about 10°C, the season lasting about 50 days. Growth of fish occurs throughout the year, but differs from year to year, resulting in variable adult size. Maximum gonadal investment of male fish is in autumn, whereas that of females is in spring. Gonadal investment of female fish, as measured by gonado-somatic index and fecundity, is higher than in other studied leiurus populations, but the number of clutches produced in a season is probably low. These differences in life history from other studied populations of sticklebacks are seen as adaptations to a mediterranean-type climate (high summer temperatures, seasonality of water bodies) and to heavy predation by fish-eating birds.     

Life history patterns of a livebearing fish in contrasting environments

Summary The population dynamics and energy allocations of the Gila topminnow, a small livebearing fish, were studied in two contrasting environments, a spring run of constant characteristics and a fluctuating desert wash. Topminnows grew and matured in two basic patterns. First, many fish in both areas matured the year after their birth. Second, spring fish born early in the breeding season grew rapidly, bred within five months, and died by eight months of age. Although spring fish assimilated more energy, wash fish actually expended more calories for growth and reproduction, partly because of lower maintenance costs. Reproductive effort of long-lived spring fish varied with age between 3.1 and 6.5%; whereas efforts of short-lived spring and wash fish increased steadily with age to 5.2 and 9.8%, respectively. Although spring fish produced eggs of higher energy content, females in both areas varied their investment per offspring, apparently tracking seasonal changes in the availability of food for fry. When long-lived spring fish experienced food shortage, they allocated less energy to both growth and reproduction; in contrast, wash and short-lived spring fish under similar conditions reduced only their growth allocation. The reproductive mass in spring fish appeared to be limited by food availability, incompletely filled the abdominal space, and reflected no tradeoff between fecundity and investment per offspring. Reproduction by wash fish appeared to be limited by body space and was characterized by a tradeoff between fecundity and egg size.     

Life history patterns of river invertebrates

The initiation of invertebrate distribution patterns in rivers occurs by choice of oviposition sites and is influenced by the evolved reproductive strategies of the individual species. Subsequent redistribution by migration or drifting establishes patterns which are then modified by environmental influences on growth and mortality. Continuity of life cycles is sustained by variations on a number of defined life history strategies combined with evolved behavioural responses.     

Life cycle cost analysis of the UK housing stock

Purpose

The aim of the paper is to estimate life cycle costs (LCC) of the current housing stock in the UK as part of sustainability assessment of the residential construction sector. This is carried out by first estimating the life cycle costs of individual houses considering detached, semi-detached and terraced homes. These results are then extrapolated to the UK housing stock consisting of seven million each of semi-detached and terraced houses and four million of detached houses. A brief discussion of life cycle environmental impacts is also included to help identify improvement opportunities for both costs and impacts.

Methods

The life cycle costing methodology followed in the study is congruent with the life cycle assessment methodology. The system boundary for the study is from ‘cradle to grave’, including all activities from extraction and manufacture of construction materials to construction and use of the house to its demolition. The functional unit is defined as the construction and occupation of a house in the UK over the lifetime of 50 years.

Results and discussion

The total life cycle costs are estimated at £247,000 for the detached house, £192,000 for the semi-detached and £142,000 for the terraced house. The running costs in the use stage contribute 52 % to the total life cycle costs of which half is from energy use. The construction costs contribute 35 % to the total LCC with the walls and the roof being the most expensive items. The remaining 13 % of the costs are incurred at the end of life of the house which are largely (85 %) due to the cost of labour for demolition. Recovery of end-of-life materials has a limited potential to reduce the overall life cycle costs of a house. The life cycle costs of the whole housing stock are estimated at £67 billion per year or £3,360 billion over the 50-year lifetime.

Conclusions

The existing housing stock in the UK is facing a number of challenges that will need to be addressed in the near future. These include improving energy efficiency and reducing the dependency on fossil fuels to reduce energy demand, fuel poverty and environmental impacts. Furthermore, the disparity between the construction costs and house market prices will need to be addressed to ensure that access to housing and house ownership do not become the privilege of a few.     

Life history characteristics of the estuary eeltail catfish Cnidoglanis macrocephalus (Plotosidae) in eastern Australia

The biology and fisheries of cobbler Cnidoglanis macrocephalus have been examined on the Australian west coast, but not the east coast. This study identified that east coast estuary cobbler was more prevalent over vegetated habitat than bare substrata and that spawning occurred during spring and early summer. Observed longevity was 9⁺ and 20⁺ years for males and females, but there were no discernible differences between sexes or estuaries in mean total length (TL) at age. The von Bertalanffy growth function of combined sexes was L_inf?=?61.2 cm TL, k?=?0.677, t₀?=?0.007. The data demonstrate similarities and differences in life history characteristics of cobbler between coasts.

     

Life history predicts risk of species decline in a stochastic world

Understanding what traits determine the extinction risk of species has been a long-standing challenge. Natural populations increasingly experience reductions in habitat and population size concurrent with increasing novel environmental variation owing to anthropogenic disturbance and climate change. Recent studies show that a species risk of decline towards extinction is often non-random across species with different life histories. We propose that species with life histories in which all stage-specific vital rates are more evenly important to population growth rate may be less likely to decline towards extinction under these pressures. To test our prediction, we modelled declines in population growth rates under simulated stochastic disturbance to the vital rates of 105 species taken from the literature. Populations with more equally important vital rates, determined using elasticity analysis, declined more slowly across a gradient of increasing simulated environmental variation. Furthermore, higher evenness of elasticity was significantly correlated with a reduced chance of listing as Threatened on the International Union for Conservation of Nature Red List. The relative importance of life-history traits of diverse species can help us infer how natural assemblages will be affected by novel anthropogenic and climatic disturbances.