Anopheles culicifacies giles: Adult ecological parameters measured in rural punjab province,pakistan using capture-mark-release-recapture and dissection methods,with comparative observations onAn. stephensi liston andAn. subpictus grassi

Dispersal, immigration and emigration rates, horizontal and vertical survivorship and absolute population size were estimated for micropopulations of An. culicifacies, An. stephensi and An. subpictus at a series of cattle sheds in rural Punjab Province, Pakistan, during November 1979 and May 1980 using capture-mark-release-recapture and dissection methods. Dispersal was temperature-related, with populations more vagile during May. Mean dispersal distance per individual was low for all species. More than 70% of all recaptures were taken at the point of release and the longest detected flight was 1250 meters. Horizontal survivorship was greater during November and was always less than vertical survivorship calculated from dissection agegrading data. Survivorship during the nulliparous period was greater than survivorship throughout total life, indicating the survivorship curve may be slightly sigmoid. Daily population sizes of endemic and immigrating females and males were calculated usingBailey 's (1952) modification of the Lincoln Index, with the daily captures adjusted for immigration which was highest in May. Daily additions to the indoor resting population exclusive of immigrants were estimated using the method ofManly andParr (1968). The relationship of the present findings to malaria transmission and genetic control were discussed.     

Physiological age-grading and ovarian physiology of Prostephanus truncatus

Abstract. The reproductive tracts of male and female Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) were described for beetles between emergence and 30 days old in order to determine age-grading criteria. Seminal vesicles were bigger among non-mated males than among mated males due to accumulation of sperm; no age-specific differences were found for male P. truncatus. Ovaries (germarium size, number of follicles and follicle size) were similarly developed for females between 5 and 30 days old and did not differ between mated and non-mated females. Starved females were found to resorb follicles. Yellow body formation was strongly dependent on age, and was used as an age-grading criterion for female P. truncatus. Females flying off maize cobs and caught with pheromone traps were of varying physiological age and mated, and their ovarian development was suspended. All migrating females were mated, indicating that lone females may act as colonizers, independently of males. The applicability of migration theories to P. truncatus and adaptive inter-reproductive dispersal as part of its life history strategy are discussed.     

Grizzly bear population vital rates and trend in the Northern Continental Divide Ecosystem,Montana

We estimated grizzly bear (Ursus arctos) population vital rates and trend for the Northern Continental Divide Ecosystem (NCDE), Montana, between 2004 and 2009 by following radio-collared females and observing their fate and reproductive performance. Our estimates of dependent cub and yearling survival were 0.612 (95% CI = 0.300–0.818) and 0.682 (95% CI = 0.258–0.898). Our estimates of subadult and adult female survival were 0.852 (95% CI = 0.628–0.951) and 0.952 (95% CI = 0.892–0.980). From visual observations, we estimated a mean litter size of 2.00 cubs/litter. Accounting for cub mortality prior to the first observations of litters in spring, our adjusted mean litter size was 2.27 cubs/litter. We estimated the probabilities of females transitioning from one reproductive state to another between years. Using the stable state probability of 0.322 (95% CI = 0.262–0.382) for females with cub litters, our adjusted fecundity estimate (m_x) was 0.367 (95% CI = 0.273–0.461). Using our derived rates, we estimated that the population grew at a mean annual rate of approximately 3% (λ = 1.0306, 95% CI = 0.928–1.102), and 71.5% of 10,000 Monte Carlo simulations produced estimates of λ > 1.0. Our results indicate an increasing population trend of grizzly bears in the NCDE. Coupled with concurrent studies of population size, we estimate that over 1,000 grizzly bears reside in and adjacent to this recovery area. We suggest that monitoring of population trend and other vital rates using radioed females be continued. © 2011 The Wildlife Society.     

Survival,density and population composition of bellbirds (Anthornis melanura) on the Poor Knights Islands,New Zealand

Abstract

Annual survival by age, sex and population size and structure were estimated for bellbirds (Anthornis melanura) from a banding study undertaken on 66 ha Aorangi Island, the Poor Knights Islands, during the period 1978–86. The most parsimonious model showed that survival varied little with age and between years, and survival of males was significantly greater than that of females. Recapture probabilities of males and females were similar, but did vary with age and among years. There was a greater proportion of adult males than adult females and sub‐adult males and females in the population, and among adults the male bias in the population was greater during the breeding season than at other times of the year. The high density of bellbirds on the Poor Knights and larger size of males may explain the reduced survival of females relative to that of males.     

Yearly variation in recruitment and its effect on population dynamics inYoldia notabilis (Mollusca: Bivalvia), analyzed using projection matrix model

Long-term variation in recruitment was estimated by constructing projection matrices for a marine bivalve, Yoldia notabilis, at two stations in Otsuchi Bay, northeastern Japan, and the effects of its variation on population dynamics were examined using a simple matrix model. The matrix model was developed from the Leslie matrix, in which the population growth rate λ was expressed as a function of recruitment rate r₀. The equilibrium recruitment rate r_s, or the recruitment rate required to maintain population at constant size (λ=1), was expressed by the reciprocal of the reproductive value of a newly recruited individual. The estimates of r_s for the field population were lower at the shallower station than at the deeper station, reflecting higher survivorship and fecundity. Past recruitment rate estimated both by the field samplings for 3 years and by the back-calculation from the current age structure for over 10 years showed large yearly variation, ranging between 0 and 58.6×10⁻⁴. The estimates were larger than r_s, and hence, large enough to increase population size (λ>1) only in approximately one-third of the estimated years. This suggests that the population has been maintained by occasional successful recruitment occurring once every few years.     

EVOLUTION OF UNISEXUALITY IN THE HAWAIIAN FLORA: A TEST OF MICROEVOLUTIONARY THEORY

The evolution of separate sexes as a means of avoiding self-fertilization requires the controversial coexistence of large inbreeding depression and high selfing rate in the ancestral hermaphrodite population. Fitness components of adult females and hermaphrodites in nature, of their open-pollinated progeny, and of experimental selfs and outcrosses onto hermaphrodites were compared in endemic Hawaiian Bidens sandvicensis, all of whose known populations are gynodioecious, consisting of a mixture of females and hermaphrodites. Multilocus selfing rates of hermaphrodites were also estimated, and sex morph ratio monitored over four seasons in three populations of B. sandvicensis and one population of gynodioecious B. cervicata. Total mean inbreeding depression in seed set (in the glasshouse), germination rate (in an open-air nursery on Kauai), and first year survivorship and fecundity in the field were estimated as 0.94 (SE 0.04), and occurred primarily in drought months. Lower survivorship and fecundity of selfs were partially explained by their consistently smaller size. Open-pollinated seed of females had significantly lower germination rate, proportion flowering, and fecundity than outcrossed progeny of hermaphrodites, suggesting moderate biparental inbreeding in females and a lack of any non-outcrossing advantage to progeny of females. In all fitness components, open-pollinated progeny of hermaphrodites were inferior to those of females and to outcrosses, and in most components were superior to selfs. Total performance of open-pollinated progeny of females relative to those of hermaphrodites was calculated as 2.3 (SE = 0.4), but since inflorescences of females also set 20% to 50% more seed than those of hermaphrodites, their total relative ovule success was estimated as 3.2 (SE = 0.5). If inheritance of male sterility is nuclear, this superiority is sufficient to maintain females in frequencies over 20% in populations, whose actual frequencies ranged from 14% to 33%. In four populations, selfing rates of hermaphrodites, assayed in seedlings, were 0.50, 0.45, 0.25, and 0.30, but since substantial inbreeding depression occurred prior to germination, the mean selfing rate of hermaphrodite ovules exceeded 0.57. Female frequencies were significantly higher in the two populations with higher hermaphrodite selfing rate. These results suggest that inbreeding depression can exert a profound influence on the mating system of self-compatible plants on Hawaii and perhaps other oceanic islands, and can be sufficiently strong to electively favor the elimination of the male function.     

Low effective population size and survivorship in a grassland grouse

Assessments of census size (N _c) and effective population size (N _e) are necessary for the conservation of species exhibiting population declines. We examined two populations (Oklahoma and New Mexico) of the lesser prairie-chicken (Tympanuchus pallidicinctus), a declining lek-breeding bird, in which one population (Oklahoma) has larger clutch size and more nesting attempts per year but lower survival caused by human changes to the landscape. We estimated demographic and genetic estimates of N _e for each population and found that both populations have low N _e estimates with a risk of inbreeding depression. Although Oklahoma females produce a larger number of offspring, the proportion of females successfully reproducing is not higher than in New Mexico. Higher reproductive effort has likely reached a physiological limit in Oklahoma prairie-chickens but has not led to a higher N _e or even a larger N _c than New Mexico. We propose that future conservation efforts focus on maximizing survivorship and decreasing the variance in reproductive success because these factors are more likely than increasing reproductive output alone to yield population persistence in lek-breeding species.     

Larval host plant affects fitness consequences of egg size variation in the seed beetle Stator limbatus

Egg size variation often has large effects on the fitness of progeny in insects. However, many studies have been unable to detect an advantage of developing from large eggs, suggesting that egg size variation has implications for offspring performance only under adverse conditions, such as during larval competition, periods of starvation, desiccation, or when larvae feed on low-quality resources. We test this hypothesis by examining the consequences of egg size variation for survivorship and development of a seed-feeding insect, Stator limbatus, on both a low-quality (Cercidium floridum) and a high-quality (Acacia greggii) host plant. Our results are consistent with the hypothesis. S. limbatus larval performance was affected by egg size only when developing on the poor-quality host (C. floridum); larvae from large eggs survived better on C. floridum than those from small eggs, while there was no evidence of an effect of egg size on progeny development time, body weight, or survivorship when larvae developed on A. greggii. These results indicate intense selection for large eggs within C. floridum-associated populations, but not in A. greggii-associated populations, so that egg size is predicted to vary among populations associated with different hosts. Our results also support this hypothesis; females from a C. floridum-associated population (Scottsdale) laid larger eggs than females from an A. greggii-associated population (Black Canyon City).     

Space Use,Survival, Movements,and Reproduction of Reintroduced Louisiana Black Bears

ABSTRACT Studies of reintroduced animals are beneficial to evaluate the success of reintroduction programs and to understand factors influencing fitness of reintroduced individuals. The geographic distribution of the federally threatened Louisiana black bear (Ursus americanus luteolus) has been reduced to 3 isolated populations due to habitat loss and excessive harvest. We reintroduced 23 adult female Louisiana black bears and their cubs to east-central Louisiana, USA, and documented postrelease space use, survival, movements, and reproduction. Individual females used larger home ranges after reintroduction than they had in the source population (P = 0.037). Spring ranges of reintroduced females were smaller than summer, autumn, and annual ranges (all P < 0.09), which did not differ from each other (all P > 0.60). Survival of reintroduced females did not differ between their first (S = 0.933) and second (S = 1.00) year after release or from annual survival of females in the source population (S = 0.964–1.00). Mean straight-line distance traveled by females from their release sites to the center of established home ranges or last recorded locations was 22.7 km. Six females reproduced after reintroduction and produced 15 cubs. Mean postrelease litter size of parturient reintroduced females (2.5) was similar to reported mean litter size of females in the source population (2.4). Our results suggest that the Louisiana reintroduction program is proceeding favorably; however, future studies should continue to monitor survival and reproduction of reintroduced females in Louisiana. Additional demographic parameters (i.e., cub survival) should be estimated to allow for population viability analysis to determine if the new population is self-sustaining.     

Population structure of the rare damselfly,Ischnura gemina (Kennedy) (Odonata: Coenagrionidae)

Summary The population structure of the endemic San Francisco Bay Area damselfly, Ischnura gemina, is examined using mark-recapture methods. Average daily movements, sex ratios, population size, maturation times, survivorship, and dispersion patterns, were recorded and calculated from two small (each less than one hectare) sites 150 m apart in Glen Canyon, San Francisco. Of 563 adults marked over 36 days, 412 (73%) were recaptured at least once. Average daily movements for males and females were less than 6 m, suggesting local movements. However, directional movements of 150 m were observed from one site to the other, indicating dispersal potential. One of the populations was a satellite composed entirely, of emigrating individuals from the other site; no larvae or teneral adults were found at the satellite area. Males were more aggregated than females at both sites. Both sexes were highly clumped at one site but were nearly randomly dispersed at the other site. Total population size for both sexes tended to be constant throughout the sampling period, at about 250. Adult population estimates showed more males were present than, females, but larval counts at one site indicated only a slight excess of males. Average life span estimates ranged from 6.5 days (females) to 23.3 days (males). One male lived at least 36 days. Maturation time for males was about 5–7 days, 7–10 days for females. A long life span and long flight season (March to November) are probably adaptations to the foggy San Francisco climate. All populations of I. gemina located to date are small, possibly originating from founders from nearby demes, and may be subject to different selection pressures. The dispersal potential of I. gemina may increase its chance of survival should small urban demes be threatened with destruction.     

Sustainability of the South China tiger: implications of inbreeding depression and introgression

The South China tiger (Panther tigris amoyensis) is critically endangered with 73 remaining individuals living in captivity, all derived from six wild founders since 1963. The population shows a low level of juvenile survivorship and reproductive difficulties, and faces a huge conservation challenge. In this study, inbreeding depression and genetic diversity decline were examined by using pedigree data and 17 microsatellites. The constant B, which is related to the number of lethal equivalents, was estimated to be 0 for the offspring of noninbred parents, but was >0 for the offspring of inbred parents and for all offspring. Percentage of successfully breeding tigers inversely correlated with inbreeding level (r = −0.626, α = 0.05). Taken together, these findings suggest the population is suffering from inbreeding depression in juvenile survivorship and fecundity. No significant correlation was detectable for the mean litter size with f of either dams (r = −0.305, α = 0.46) or kittens (r = 0.105, α = 0.71), indicating litter size was not strongly subject to inbreeding depression. The average number of alleles per locus was 4.24 ± 1.03 (SE), but effective number of alleles was only 2.53 ± 0.91. Twenty-one alleles carried by early breeders at 13 loci were absent in the present breeders and potential breeders. Multilocus heterozygosity was inversely correlated with inbreeding levels (r = −0.601, α = 0.004). These findings suggest rapid allelic diversity loss is occurring in this small captive population and that heterozygosity is being lost as it becomes more inbred. Our phylogenetic analysis supports past work indicating introgression from northern Indochinese tigers in the population. As no wild representatives of the South China tiger can be added to the captive population, we may consider the alternate scenario of further introgression in the interest of countering inbreeding depression and declining genetic diversity.     

Oviposition preference and offspring performance in <Emphasis Type="Italic">Mechoris</Emphasis><Emphasis Type="Italic">ursulus</Emphasis> Roelofs (Coleoptera: Attelabidae)

Oak nut weevil (Mechoris ursulus Roelofs) females lay eggs in acorns and cut off the branch of oviposited acorns. We investigated the relationship between oviposition preference and offspring performance (growth and survival). M. ursulus appeared to estimate the size of an acorn by walking around it before and after oviposition. When we offered paired acorns of different sizes, females showed strong preference for larger acorns. In the field, egg-bearing acorns were larger than egg-free acorns in cut branches. A parallel series of experiments was conducted to assess the influence of acorn size on offspring performance. Larvae and newly emerged adults from larger acorns were heavier than those from smaller acorns. However, acorn size did not affect the survivorship of larvae. We also tested if M. ursulus avoided oviposited acorns, but there was no evidence that M. ursulus could assess the presence of eggs in acorns. Electronic Publication     

Within-harem competition among Ips females, an overlooked component of density-dependent larval mortality

Intraspecific larval competition is commonly believed to be the major component of egg-to-adult mortality in bark beetles. Larval mortality is usually shown to be density dependent. In this study I looked specifically at competition among females in the same gallery system, in a sparse but highly female-biased population of Ips acuminatus breeding in cut pine branches near Kongsberg, southeastern Norway. Supplementary data from a slightly female-biased population in western Norway and a population with intermediate female bias in W. Germany are also provided. Survivorship from egg to adult or pupa was measured in laboratory experiments, for the area in which larvae from different arms potentially competed relative to survivorship in areas away from competition. Survivorship was significantly correlated with both average interarm distance (r²= 0.76) and food per larva (cm² per larva: r²= 0.73). There was no evidence that females could detect the presence of other, nearby egg arms: neither egg spacing (on the arm sides nearest each other) nor interarm distance increased when two arms were near each other. Nor did females distribute themselves optimally within harems, though the distribution of egg arms within harems was significantly different from that expected from random settling. analysis of interarm distances and harem sizes in 1984 branches revealed that a minimum of 34% of arm sides could be expected to suffer considerably reduced larval survivorship due to within-harem competition. Harem size in Ips typographus is reviewed, and data on the distribution of females within harems is presented for Norwegian populations of I. Typographus, Orthotomicus erosus and O. laricis. Evidence from the literature is presented to show that uneven distribution of females between harem sides is not uncommon. I suggest that the findings for Ips acuminatus are applicable to a wide range of harem polygynous scolytids, including I. typographus: the factors influencing density cannot be fully understood without taking into account the distribution of females among males and the distribution of females within harems.     

Long-term variability and density dependence in Hudson River Dreissena populations

1. We used a 27-year record of Dreissena populations in the freshwater tidal Hudson River to describe interannual variation in population density, body size, and body condition; estimate long-term variation in recruitment, survivorship, and shell growth; and assess possible controls on the populations.
2. Dreissena populations in the Hudson have been highly variable, with interannual ranges of c. 100-fold in abundance and biomass, and 7-fold in mean body mass. This large interannual variation arises from both long-term trends and 2–5-year cycles.
3. Long-term trends include the 2008 appearance of the quagga mussel (Dreissena rostriformis), which still forms a small part (<10%) of the dreissenid community, and a decline in zebra mussel body size. The decline in body size was caused by a long-term decline in adult survivorship rather than a decline in rates of shell growth. We could detect no long-term trends in adult abundance or spread of Dreissena onto soft sediments in the Hudson.
4. We observed persistent, strong cycles in adult abundance and body size. These were driven by the appearance and decay of eight dominant year classes over the 27 years of our study, and were a result of temporal variation in recruitment rather than temporal variation in survivorship. The observed strongly irregular recruitment appears to arise from strong adult–larval interactions, and is consistent with previous simulation model results showing that interactions between adults and larvae can drive persistent cycling.
5. We found evidence that negative density dependence affects recruitment, somatic growth, and body condition of Dreissena in the Hudson. Warm summers may also cause high adult mortality.
6. We put our results into the context of a conceptual model of Dreissena population dynamics, and argue that neither the dynamics nor the controls of populations of these important invaders is known satisfactorily.

     

Age and growth of the Black Sea turbot, Psetta maxima (Linneaus, 1758) (Pisces: Scophthalmidae), estimated by reading otoliths and by back-calculation

Age and growth of the Black Sea turbot, Psetta maxima, were determined from a total of 1445 individuals collected along the eastern Black Sea coast between 1990 and 1996. Age was estimated by interpreting growth rings in whole and broken sagittal otoliths. The former method underestimated the age over 5 years, and a maximum age of 11 years was observed by the latter. Marginal increment analysis clearly showed that a single annulus is formed in early summer each year. Growth in length differed between sexes, and females attained a larger size than males at the same age. No significant difference was found between the mean observed total length (TL), the back‐calculated TL derived from radius measurements and the TL estimated from otolith size–fish size relationship. The von Bertalanffy growth parameters estimated by the length‐at‐age data were: L_∞ = 96.24 cm; K = 0.119 year^?1; t₀ = ?0.01 year for the entire population.     

Growth and survivorship as proximate causes of sexual size dimorphism in peninsula dragon lizards Ctenophorus fionni

Males and females differ in body size in many animals, but the direction and extent of this sexual size dimorphism (SSD) varies widely. Males are larger than females in most lizards of the iguanian clade, which includes dragon lizards (Agamidae). I tested whether the male larger pattern of SSD in the peninsula dragon lizard, Ctenophorus fionni, is a result of sexual selection for large male size or relatively higher mortality among females. Data on growth and survivorship were collected from wild lizards during 1991–1994. The likelihood of differential predation between males and females was assessed by exposing pairs of male and female lizards to a predator in captivity, and by comparing the frequency of tail damage in wild‐caught males and females. Male and female C. fionni grew at the same rate, but males grew for longer than females and reached a larger asymptotic size (87 mm vs. 78 mm). Large males were under‐represented in the population because they suffered higher mortality than females. Predation may account for some of this male‐biased mortality. The male‐biased SSD in C. fionni resulted from differences in growth pattern between the sexes. The male‐biased SSD was not the result of proximate factors reducing female body size. Indeed SSD in this species remained male‐biased despite high mortality among large males. SSD in C. fionni is consistent with the ultimate explanation of sexual selection for large body size in males.     

Fitness decline in spontaneous mutation accumulation lines of Caenorhabditis elegans with varying effective population sizes

The rate and fitness effects of new mutations have been investigated by mutation accumulation (MA) experiments in which organisms are maintained at a constant minimal population size to facilitate the accumulation of mutations with minimal efficacy of selection. We evolved 35 MA lines of Caenorhabditis elegans in parallel for 409 generations at three population sizes (N = 1, 10, and 100), representing the first spontaneous long-term MA experiment at varying population sizes with corresponding differences in the efficacy of selection. Productivity and survivorship in the N = 1 lines declined by 44% and 12%, respectively. The average effects of deleterious mutations in N = 1 lines are estimated to be 16.4% for productivity and 11.8% for survivorship. Larger populations (N = 10 and 100) did not suffer a significant decline in fitness traits despite a lengthy and sustained regime of consecutive bottlenecks exceeding 400 generations. Together, these results suggest that fitness decline in very small populations is dominated by mutations with large deleterious effects. It is possible that the MA lines at larger population sizes contain a load of cryptic deleterious mutations of small to moderate effects that would be revealed in more challenging environments.     

Life tables for worker honeybees

Life tables for worker honeybees covering all life span, and those for adults, were prepared for three seasonal cohorts, June bees, July bees and wintering bees. Survivorship curves for June and July bees show a convex type being exceptional for insects, with relatively high mortality at egg and feeding larval stages and at later adult stage after most bees became potential foragers. Adult longevity greatly lengthens in Winteriing bees and survivorship curve drops approximately with the same rate. A remarkable similarity of survivorship curves for men and honeybees was demonstrated, apparently due to highly developed social care in both. Some comments were given on mortality factors. The importance of life tables for population researches was shown by applying our result to the population growth curve made byBodenheimer , based upon the data byNolan . At the asymptote of the uncorrected curve, the ratio of total population estimated by uncorrected curve to that by corrected curve reaches about 3∶2.     

Energetics of isopod populations in a forest of central Japan

Energetics of the populations of three isopods, Armadillidium vulgare, Porcellio scaber and Ligidium japonicum were studied in a warm-temperate evergreen broadleaved forest of Mt. Kiyosumi in central Japan. The study deals with age composition, survivorship curves, relations of body size to number of eggs or young, and mean growth curves of the populations. Respiratory rates, calorific values and food consumptions of the individual animals were determined in the laboratory. Population density of A. vulgare was highest of the three species, being about 350/m² in June 1966. The survivorship curve of the L. japonicum population was more close to L-type than the others. Average total biomass for populations of A. vulgare, P. scaber and L. japonicum were 3.3 kcal/m², 0.67 kcal and 0.43 kcal on the monthly basis, respectively. The energy of 35.2 kcal/m² was estimated to be assimilated by the A. vulgare population, 7.84 kcal by P. scaber and 6.91 kcal by L. japonicum during the period from October 1965 to September 1966. The relations between assimilation A and production P for fish, grasshopper and isopod populations were found to be expressed as A=aP^b. The values of the constant a for the fish, grasshopper and isopod populations seem to be in the range from 10 to 25, from 2 to 7 and from 4 to 8, respectively. Production efficiencies presented as P/A of A. vulgare, P. scaber and L. japonicum populations were estimated as 19.1%, 15.3% and 13.1%, respectively. The ecological efficiency represented as M/C of these isopod populations was estimated to be in the range from 7.6% to 11. 2%. Reproduction efficiency (Rp/P) of L. japonicum population was 20%, being the highest value of the three isopod species. This may be related to the L-type survivorship curve of L. japonicum population. Reproduction efficiency, relating closely to the age structure of the population, is important in the investigation of populations of animals, particularly those that have long life span.     

The demographic and life‐history costs of fear: Trait‐mediated effects of threat of predation on Aedes triseriatus

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