Fecundity and egg size variation in North American Pacific salmon (Oncorhynchus)

We examined regional and latitudinal variation in fecundity and egg weight for five species of Pacific salmon ( Oncorhynchus ) along the Pacific coast of North America. Data were examined for 24 chum salmon, 15 pink salmon, 34 sockeye salmon, 44 chinook salmon, and 40 coho salmon populations from published sources, unpublished Canadian hatchery records, our own laboratory investigations, and other unpublished sources. Substantial regional variation in fecundity and egg weight was observed, with salmon on the Queen Charlotte Islands and Vancouver Island in British Columbia generally having lower fecundity and larger egg size than nearby mainland populations. The relative distance of freshwater migration to the spawning grounds generally had a marked effect on both fecundity and egg size, with populations spawning in the upper portions in the drainages of large rivers like the Fraser River in British Columbia having reduced fecundity and egg size compared with coastal spawning populations. Fecundity was generally higher and egg size generally lower in more northern populations of sockeye, chinook, and coho salmon compared with southern ones. We suggest that egg size tends to be lower in northern populations of some species as a result of increased fecundity due to their older ages at maturity and a limited amount of energy that can be expended on egg production.     

Fecundity and its variability in orange roughy: effects of population density, condition, egg size, and senescence

Fecundity of orange roughy in 1987–1989 adjusted for standard length (S.L.) varied significantly between New South Wales (42 787 eggs female⁻¹) South Australia (35 339 eggs female⁻¹) and east Tasmania (31 085 eggs female⁻¹). Only 10-17% of the variability in fecundity of eastern Tasmania orange roughy was explained by s.l . in any year from 1987–1992. However, liver condition and age of the fish, in combination with s.l ., explained 27% of the variation in fecundity. Fecundity declined in fish over 60 years old. It was also significantly correlated with lipid levels in the ovary, in particular, with triacylglycerol as a proportion of the total lipid fraction. Significant interannual changes in fecundity appeared to be related to the impact of fishing. From 1987–1992, the orange roughy stock off east Tasmania was reduced by 50% by the fishery, and mean fecundity increased 20% over that period. This compensatory increase in individual fecundity, combined with an apparent increase in the proportion of females spawning annually from 54 to 71%, limited the decline in the population's egg production over this period to approximately 15%.     

Analysis of non‐Saccharomyces yeast populations isolated from grape musts from Sicily (Italy)

Aims: The aim of this study was to identify the non‐Saccharomyces yeast populations present in the grape must microflora from wineries from different areas around the island of Sicily. Methods and Results: Yeasts identification was conducted on 2575 colonies isolated from six musts, characterized using Wallerstein Laboratory (WL) nutrient agar, restriction analysis of the amplified 5·8S‐internal transcribed spacer region and restriction profiles of amplified 26S rDNA. In those colonies, we identified 11 different yeast species originating from wine musts from two different geographical areas of the island of Sicily. Conclusions: We isolated non‐Saccharomyces yeasts and described the microflora in grape musts from different areas of Sicily. Moreover, we discovered two new colony morphologies for yeasts on WL agar never previously described. Significance and Impact of the Study: This investigation is a first step in understanding the distribution of non‐Saccharomyces yeasts in grape musts from Sicily. The contribution is important as a tool for monitoring the microflora in grape musts and for establishing a new non‐Saccharomyces yeast collection; in the future, this collection will be used for understanding the significance of these yeasts in oenology.     

Fecundity, body size and population dynamics of Chrysomya albiceps (Wiedemann, 1819) (Diptera: Calliphoridae).

In this study, the seasonal variation of fecundity, wing and tibia length were investigated in natural populations of Chrysomya albiceps (Wiedemann, 1819) in an attempt to determine the changes in life history of the species as a function of seasonality. A relative constant temporal trajectory was found for fecundity, wing and tibia length over twenty-four months. Positive correlations between fecundity and wing size, fecundity and tibia size and wing and tibia sizes were observed. The implications of these results for population dynamics of C. albiceps are discussed.     

Fecundity and egg viability in relation to female body size in Neodiprion sertifer (Hymenoptera: Diprionidae)

Relationships between female size and fecundity, egg viability and embryonal development were studied in Neoriprion sertifer. Sawfly females, reared from the 1st instar larvae on Scots pine needles heavily affected by industrial pollutants or on relatively unpolluted needles, were induced to lay eggs parthenogenetically in the field in Finland. Females reared on polluted needles were smaller and oviposited an average of 68.8 eggs, and those reared on unpolluted needles 79.4 eggs per female. However, the higher egg viability in the former group masked the effect of reduced female size. This compensation was primarily related to the size of the females, larger individuals producing relatively fewer viable eggs in both groups.     

The urban vascular flora of Palermo (Sicily,Italy)

Abstract

This article presents a comprehensive inventory of the urban vascular flora of the town of Palermo. The data were gathered from extensive field collections, from specimens kept in different herbaria, and publications of the last 30?years. The floristic catalogue includes all the vascular plants that occur spontaneously within the urban area. Thirteen taxa are endemic to Sicily and one of these, Clinopodium raimondoi, is exclusive to Palermo’s area. The inventory comprises 1052 taxa belonging to 119 families and 225 genera, and contains 170 taxa non-native to the Italian flora.     

Fecundity,spore recruitment and size in Gelidium sesquipedale (Gelidiales,Rhodophyta)

Gelidium sesquipedale fecundity was quantified by counting tetrasporangial sori and cystocarps per meter squared and by estimating the number of spores contained inside them. These were obtained by regression on a size metric of reproductive structures. Tetrasporangial sori length and cystocarp thickness were the best estimators of spore number. To assess spore recruitment, 12 pottery tiles were fixed to the bottom, and the appearance of small fronds was monitored.No clear seasonal pattern of reproduction was found. Tetraspore production peaked in March 1990 with 10.4 × 10⁶ spores m^–2, whereas the carpospore peak was lower, 4.9 × 10⁵ spores m^–2 in July 1989. Recruitment followed tetraspore peaks. The probability of a G. sesquipedale tetraspore making the transition to a recruit was 4.7 × 10^–5. Frond length was significantly related to tetrasporangial sori number, while cystocarp number was only related to frond branching order. Minimum size for reproduction was 6.9 cm for gametophytes and 5.4 cm for tetrasporophytes; very rarely were cystocarpic fronds smaller than 9 cm, while tetrasporic fronds were often longer than 15 cm. Cystocarpic fronds were significantly shorter and had more branches than tetrasporic fronds.     

Declining egg viability explains higher hatching failure in a suburban population of the threatened Florida scrub‐jay Aphelocoma coerulescens

Hatching failure occurs in approximately 10% of all avian eggs, but varies both within and among species. This reduction in viable offspring can have significant fitness consequences for breeding parents; therefore, it is important to understand which factors influence variation in hatching failure among populations. Previous research suggests that hatching failure is higher in a suburban than in a wildland population in the Florida scrub‐jay. From 2003 to 2007, we performed two experiments to examine whether increased hatching failure in the suburbs resulted from 1) increased length of off‐bouts during incubation (predation risk hypothesis, 2003–2004) or 2) increased exposure to ambient temperature during laying (egg viability hypothesis, 2005–2007). Hatching failure was higher for females that took fewer off‐bouts, but the length of those off‐bouts did not influence hatching failure. Thus, nest predation risk does not appear to explain higher hatching failure in the suburbs. Alternatively, hatching failure increased with increasing exposure of eggs to ambient conditions during the laying period. First‐laid eggs in the suburbs had the greatest pre‐incubation exposure to ambient temperature and the greatest rate of hatching failure, consistent with the egg viability hypothesis. Urbanization influences hatching failure through a series of complex interactions. Access to predictable food sources advances mean laying date in suburban scrub‐jays, leading to larger clutch sizes. Because scrub‐jays begin incubation with the ultimate egg, first‐laid eggs in the suburbs may be exposed to ambient temperatures for longer periods, thus reducing their viability.     

Fecundity, lifespan and egg mass in butterflies: effects of male-derived nutrients and female size

1. Effects of larval reserves and nutrients received as adults on fecundity and lifespan in female Danaus plexippus (the Monarch Butterfly) were measured to determine the relative importance of different sources of nutrients for reproduction and somatic maintenance.
2. Egg-laying lifespan was correlated with female size but not with the amount of male-derived nutrients or adult food concentration.
3. Lifetime fecundity was higher when females received a large first spermatophore, but was not affected by female size when lifespan was controlled or by adult food concentration.
4. At the end of their lives, females contained unlaid eggs and retained, on average, 88% of their initial mass. This proportion was unchanged in two years, although mean egg-laying lifespan varied from 22·5 to 28·7 days.
5. Egg mass decreased over the female lifespan, and was correlated with female size.
6. These results suggest that larval reserves are more important for somatic maintenance than adult income, but that the protein-rich nutrients received from males contribute to egg production. This supports theoretical predictions and empirical studies of other Lepidoptera showing that larval reserves are less likely to affect fecundity when the adult income can contribute substantially to egg production.     

Importance of water-level fluctuation on population dynamics of cladocerans in a hypertrophic reservoir (Lake Arancio,south-west Sicily,Italy)

During a period of three years (1990–1991 and 1993),we studied the population dynamics of planktoniccladocerans in a hypertrophic reservoir. Weeklysampling revealed that the five most common speciesfollowed a trend which reflects the peculiarhydrological characteristics of the reservoir andtheir key position in the pelagic food web. Inparticular, 1991 was characterized by a strong waterinflow which probably interfered with the reproductiveactivities of the dominant fish population (Rutilus rubilio) and reduced the concentration ofinedible planktonic algae allowing the development ofsmall Chlorococcales. This event was associated withhigher population densities of Daphnia hyalinacompared to the other years of the survey. In spring1991, an extended clear-water phase was observed andSecchi disk depth increased to 6 m, whereas in theother years it did not surpass 1 m. In addition, theD. hyalina population persisted throughout thesummer in 1991, whereas it started to decline at theend of June in the other years. This development ofD. hyalina probably influenced the populationdynamics of the other cladoceran species in thereservoir, and in particular reduced the summer growthof Diaphanosoma lacustris and delayed theoccurrence of Bosmina longirostris. Stomachanalysis indicated that D. hyalina is thepreferred food item of juvenile (less than two monthsold) R. rubilio. Overall, the hydrology of thereservoir was observed to interact with the trophicprocesses in the pelagic environment of the ecosystemin at least two different ways: via bottom-upprocesses, influencing phytoplankton dynamics, and viatop-down processes, regulating the predationefficiency of the planktivores.     

Effects of gravel size and peat material concentrations on embryo survival and alevin emergence of brown trout,Salmo trutta L.

Embryo survival and alevin emergence pattern of brown trout were studied in simulated redds with different homogeneous gravel sizes and different concentrations of peat material. Optimal survival (95%) occurred in 18 mm gravel and survival decreased with decreasing gravel size. High concentrations (40%) of peat material resulted in low survival (65%). The proportion of premature emerging alevins increased in finer gravels and at high peat concentrations. Premature alevins had a large yolk sac and are probably very vulnerable to predators.     

Distribution,ecology and conservation survey on Trifolium michelianum Savi (Fabaceae) in Sicily (Italy)

We report the identification of four residual stations for Trifolium michelianum Savi (Fabaceae) in Sicily, whereas the species was documented to be extinct at the Gorgo Cerro station (western Sicily), the only locality previously reported in the literature. In addition to an update on the distribution of the species, a survey on the new Sicilian populations led to their biological, ecological and phytosociological characterization, as well as to an assessment of the risk factors. The species, here relegated to the limit of its distribution area, occurs in particularly sensitive and vulnerable environments, such as the “Mediterranean temporary ponds”, considered “priority” by the Council Directive 92/43/EEC. Moreover, a new Sicilian association (Trifolio micheliani–Glycerietumspicatae ass. nova), framed in the alliance Glycerio-Sparganion (class Phragmito-Magnocaricetea), is described.     

Distribution and population size of the threatened East Coast Akalat in Arabuko-Sokoke Forest,Kenya

Matiku, P.M., Bennun, L.A. & Nemeth, E. 2000. Distribution and population size of the threatened East Coast Akalat in Arabuko-Sokoke Forest, Kenya. Ostrich 71 (1 & 2): 282–285.

The East Coast Akalat Sheppardia gunningi sokokensis is one of six globally threatened bird species that occur in the Arabuko-Sokoke Forest, the largest remnant of forest on the East African coast. The akalat has been little studied but appears to have a patchy distribution both between and within forests. From October 1995 to February 1996 we studied the akalat's status in Arabuko-Sokoke, carrying out transect counts and plot-based surveys to determine its distribution and population size. Playback of calls was used to stimulate the bird to reveal its presence. The akalat was present in two of the forest's main vegetation types, Cynometm woodland and Mixed forest. It was absent from the more open Brachystegia woodland, and from low-canopied intermediate Cynometra and Cynometra thicket. In Cynometra woodland, the akalats were evenly distributed at high densities (estimated at 87 pairs/km²). Within the Mixed forest distribution was patchy, and the akalats were absent from areas with high human disturbance. Where the species did occur, densities were lower (estimated at 12 pairs/km²) than in the Cynometra woodland. Arabuko-Sokoke may hold up to 9 000 pairs of this species, perhaps the largest single population in the world. Most of these are in the Cynometra woodland, which is also of crucial conservation importance for the threatened Sokoke Scops Owl Otus ireneae.     

Characterization of transferrin‐linked microsatellites in brown trout (Salmo trutta) and Atlantic salmon (Salmo salar)

The transferrin (TF) gene has recently received increased interest in fish given its fitness relevance as a resistance gene against pathogenic bacteria. In this study, we characterized five TF‐linked microsatellites in brown trout (Salmo trutta) and Atlantic salmon (Salmo salar). Interestingly, each marker amplified duplicated loci and linkage analysis revealed that the TF gene has most likely experienced a tandem duplication during salmonid evolution. In addition, the amplification of all five markers across a wide range of salmonid species suggests that they may be of general interest for the genetic analysis of the TF gene(s) in this teleost family.     

Patterns of allozyme variation in relation to population size of the threatened plantMegaleranthis saniculifolia (Ranunculaceae) in Korea

Patterns of variation at 27 allozyme loci were investigated in the endangered endemic plantMegaleranthis saniculifolia. Levels of allozyme variation (A = 1.47,P = 40%,He = 0.088) were also compared with other endemic plant species. Genetic divergence between populations was very high (G ^st = 0.271 ), with moderate to high interpopulation differentiation, which probably arose through historical bottlenecks in a landscape of habitat fragmentation and/or human influence. The percentage of polymorphic loci, heterozygosity, and mean number of alleles per locus were positively related to population size, probably due to the stochastic loss of rare alleles in the smaller populations. Individuals in the small and marginal populations (TB, KD, and CJ) showed higher proportions of fixed loci. These ecologically marginal populations were typically more distant from the nearest neighboring population and were more genetically distinct from one another. The genetic structure of the current population ofM. saniculifolia is probably the result of local extinctions of intervening populations. This, in turn, is due to the Pleistocene climatic change and increased habitat destruction. A positive association appears to exist between genetic diversity and population size. Although these small population sizes are more sensitive to stochastic events, securing a certain number of individuals from the three larger populations (SB, JB, and TG) could be accomplished as part of a conservation strategy. In addition, it is important to prioritize populations in different regions in order to limit population declines caused by large-scale environmental catastrophes.     

Genetic studies in the Garfagnana population (Tuscany, Italy)

The relationship between geographic isolation and historical-demographic features and genetic structure and pattern of variation of genetic markers was analyzed in the population of Garfagnana, a semi-isolated mountainous area in the province of Lucca (Italy), taking into account hierarchical subdivisions. A random sample of unrelated individuals, whose parents were both born in this area, was typed for AB0, MN, Kell, Rh, AK, EsD, 6-PGD, AcP and ABH secretor status. The village samples were aggregated into larger population units: Two districts and six subdistricts. Comparisons were performed with population samples of the plain and the coastal area of the same province (Lucca). Phenotype and genetic differentiations among and within subdivisions were studied using G2, R statistic, Nei's method, Harpending & Ward's method and analysis of genetic distance and similarity matrices. The various parameters consistently show significant heterogeneity among the subdivisions, both at district and at subdistrict level. As expected, the gene diversity between and within subdivisions varies according to their distinctive features of isolation.     

Hieracium busambarense,a new species of the sect. Grovesiana (Asteraceae) from Sicily (Italy)

Hieracium busambarense (Asteraceae), a new species from calcareous-dolomite cliffs of Rocca Busambra (western Sicily, Italy) is described and illustrated here.     

Fecundity,reproductive effort,and pupal size in the profundal midgeChironomus cuccini (Diptera: Chironomidae)

Fecundity ofChironomus cucini increased linearly across a three-fold range of female pupal biomass. Females from a lake producing small pupae (Crystal Lake) had an average of 303 primary follicles, while larger pupae from Trout Lake had an average fecundity of 582. Pupae produced in Crystal Lake from larvae that received experimental food supplements were intermediate in size and fecundity. Pupal biomass explained 76% of the variation in fecundity. No difference in egg size was detected between pupae from the two lakes, and an average value of 2.1 g egg^–1 was used to calculate the total biomass allocated to eggs in each of 79 females dissected. This measure of reproductive effort scaled isometrically with pupal mass. On average, females allocated 48% of their biomass to eggs and 52% to somatic tissues. A comparison of average male biomass to female somatic biomass across 12 populations indicated that the biomass difference between the sexes is a biased predictor of fecundity.     

The use of first vertebrae in separating, and estimating the size of, trout (Salmo trutta) and salmon (Salmo salar) in bone remains

A method is described in which a single bone, the first vertebra, is used to distinguish bone remains of juvenile salmon ( Salmo salar ) and trout ( Salmo trutta ) with 90% certainty. A single regression of salmon and trout first vertebra-width versus fish-length of fish predicted the latter with an accuracy of ±<10 mm (95% confidence limits) for salmonids of 45–150 mm fish-length. First vertebrae were assigned to salmon or trout based on three visual characters with 89%,–90% certainty. Salmon are more variable than trout for the three characters. Of first vertebrae, 6.5% were not readily identifiable as either salmon or trout, and a further 3.0%) were misclassified using our criteria.     

Maternal effects of egg size in brown trout (Salmo trutta): norms of reaction to environmental quality

The magnitude of fitness variation caused by maternal effects and, thus, the adaptive significance of maternal traits may depend on environmental quality, generating crossing reaction norms among offspring phenotypes that shape life-history evolution. By manipulating intraclutch variation in egg size and comparing siblings we examined the maternal effects of egg size on offspring performance and tested for the existence of reaction norms to environmental quality using the brown trout Salmo trutta. When sibling groups of small and large eggs were reared separately in a hatchery environment initial size differences disappeared rapidly. However, in semi-natural environments and under direct competition, juveniles from large eggs experienced growth and survival advantages over siblings from small eggs. Moreover, distinct reaction norms existed, with the differences in performance of juveniles from small and large eggs being most pronounced in the poorer growth environments. Our results provide the first direct evidence, to our knowledge, for a causal relationship between egg size and fitness-related traits in fishes, independent of potentially confounding genetic effects. Moreover, they indicate that previous studies have been biased by experimental conditions that excluded competitive asymmetries and environmental variability. The existence of reaction norms indicates a shift in optimal egg size across gradients of environmental quality that probably shapes the evolution of this trait.