Longevity Patterns Research Articles

Alpine species seed longevity in the soil in relation to seed size and shape – A 5-year burial experiment in the Central Alps

Long-term persistent seeds are generally expected to be small and spherically shaped. In contrast, transient seeds are often large, flattened and elongated. We hypothesized that alpine species follow these trends, and that most species of unstable alpine habitats have the potential to form long-term persistent seed banks. The latter would enable them to delay germination until favourable conditions are present in their environment thereby increasing the likelihood for establishment of seedlings. We selected nine alpine species of more or less unstable habitats (i.e. Achillea moschata, Artemisia genipi, Anthyllis vulneraria ssp. alpicola, Geum reptans, Linaria alpina, Oxyria digyna, Saxifraga aizoides, Saxifraga oppositifolia, and Trifolium pallescens) for this study. Seed longevity was estimated by a 5-year burial experiment in the field with seed excavations after 1 winter, 2 years and 5 years. Germination experiments in the growth chamber and viability tests were performed after each excavation. We detected longevity patterns ranging from transient to long-term persistent. Two species were classified as transient. All other species have the potential to form persistent seed banks, with almost half of the investigated species showing a trend for long-term persistence. Despite contradictory reports, long-term persistent seed banks are an important life history trait of species of unstable alpine habitats. We found that seed shape and hard-seededness are good predictors of seed persistence of alpine species. Seed size seems to be less important. The data from this study support the general hypotheses describing the relationship among seed size, seed shape and seed persistence in the soil.

Habitat- and sex-specific life history patterns of yellow tang Zebrasoma flavescens in Hawaii, USA

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 389:245-255 (2009) - DOI: https://doi.org/10.3354/meps08114 Habitat- and sex-specific life history patterns of yellow tang Zebrasoma flavescens in Hawaii, USA Jeremy T. Claisse1,*, Marco Kienzle2, Megan E. Bushnell1, David J. Shafer1, James D. Parrish1 1University of Hawaii, Department of Zoology, 2538 McCarthy Mall, Edmondson 165, Honolulu, Hawaii 96822, USA 2CSIRO, Marine and Atmospheric Research Division, 233 Middle Street, Cleveland, Queensland 4163, Australia *Email: claisse@hawaii.edu ABSTRACT: Yellow tang Zebrasoma flavescens is the primary coral reef fish species taken in Hawaii for the aquarium trade. As part of an extensive adaptive management effort that included a network of marine protected areas that prohibited commercial aquarium fishing, an emphasis was placed on obtaining habitat- and sex-specific life history information for this valuable species. Using otolith and capture-mark-recapture methods we examined sexual differences in ontogenetic patterns of habitat use, growth rate, size dimorphism and longevity. Age validation using tetracycline to mark otoliths provided evidence that a single annulus formed each year. Yellow tang are a long-lived species (the oldest individual collected was 41 yr old) and display an asymptotic growth pattern typical of the family Acanthuridae. Median size and age at the transition between deeper coral-rich and shallow turf-dominated habitat use were about 20 mm longer and about 2 yr older for males than females and coincided with an increase in reproductive output. The sexual difference in size at habitat transition, combined with sexual size dimorphism (mean asymptotic maximum length—male: 179 mm; female 156 mm) results in differences in the size distributions of both sexes in the 2 habitats. Sexual size dimorphism resulted from a higher growth rate for males through the juvenile period. KEY WORDS: Ontogenetic habitat use · Hawaiian aquarium fishery · Acanthuridae · Model selection· Otolith · Capture-mark-recapture · Growth · Coral reef fish Full text in pdf format Supplementary material PreviousNextCite this article as: Claisse JT, Kienzle M, Bushnell ME, Shafer DJ, Parrish JD (2009) Habitat- and sex-specific life history patterns of yellow tang Zebrasoma flavescens in Hawaii, USA. Mar Ecol Prog Ser 389:245-255. https://doi.org/10.3354/meps08114Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 389. Online publication date: September 04, 2009 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2009 Inter-Research.

Longevity differs among sexes but is not affected by repeated immune activation in voles (Microtus arvalis)

Investment of resources in immune defences, despite obvious short-term benefits, may be detrimental to long-term maintenance and thus decrease longevity in absence of parasites. In addition, females and males may differ in immune investment and intrinsic longevity because they are subjected to different degrees of sexual competition and extrinsic mortality. In order to test if sex-specific investment in mounting an immune response reduced longevity, we compared the longevity of captive male and female common voles Microtus arvalis regularly challenged with keyhole limpet haemocyanin, an antigen which elicits the production of antibodies, to the longevity of voles injected with the corresponding antigen-free buffer (phosphate-buffered saline). Injections were repeated every 28 days to mimic a chronic infection. The magnitude of immune response did not vary between males and females and did not affect longevity. Overall, females lived longer than males, independently of the immune challenge. Thus, the long-term costs of immunity seem small in voles. The longevity pattern is consistent with the prediction that male-biased predation or parasitism in the wild causes reduced intrinsic lifespan, but this reduction is not mediated by a decrease in male immunity. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 328–333.

Ecological traits of a new aphid parasitoid, Endaphis fugitiva (Diptera: Cecidomyiidae), and its potential for biological control of the banana aphid, Pentalonia nigronervosa (Hemiptera: Aphididae)

Most parasitoids of aphids are small wasps belonging to the families Braconidae or Aphelinidae. However, some dipteran parasitoids are also known to use aphids as hosts. We describe and give life-history information on a new species of aphid parasitoid, Endaphis fugitiva Gagné and Muratori, found to parasitize the banana aphid, Pentalonia nigronervosa Coquerel, the vector of banana bunchy top virus. Field and laboratory observations show that fly eggs are laid on the leaves near an aphid colony, the newly hatched fly larvae search for hosts while crawling on the leaf, and then penetrate the aphid between the legs and thorax. They develop as koinobiont endoparasitoids, and eventually emerge from the aphid anus and fall to the ground to pupate in the soil. We provide data relevant to parasitoid rearing on patterns of emergence, adult longevity, and effects of pupation substrate on adult emergence rate, and we discuss the potential of this new species to contribute to the biocontrol of banana aphid in Hawaii.

Evidence of Social Nesting in the Ceratina of Borneo (Hymenoptera: Apidae)

The bee tribe Ceratinini is important for understanding early stages in social evolution. Their extant sister tribe Allodapini contains no strictly solitary species, and while some Ceratinini are commonly regarded as solitary, little behavioural data exist to substantiate this. Studies on Asian congeners have shown recurrent sociality in temperate and subtropical ranges while behavioural data are lacking in tropical regions. Field work along the west coast of Borneo in Sarawak, Malaysia, has provided some insight into these tropical taxa. Here we describe the nesting biology and social behaviour of four taxonomically described yet behaviourally unclassified Ceratina species. These four species are from three subgenera, namely Ceratina (Ceratinidia) accusator Cockerell, C. (Ceratinidia) nigrolateralis Cockerell, C. (Neoceratina) dentipes Friese, C. (Pithitis) smaragdula Fabricius. Nests of all species were typically attended by an adult female while all species except C. accusator had a low frequency of multi-female nesting assemblages. The four tropical ceratinines described here and all other behaviourally classified species exhibit recurrent patterns of maternal care, maternal longevity, and nest protection. Prolonged parental care found across the genus and occasional transitions into sociality make Ceratina of future interest for the study of life history and social evolution. The evolution of eusociality is considered one of the major transitions in evolution (Maynard Smith and Szathamary, 1995). In solitary species, offspring disperse and reproduce independently whereas workers in eusocial societies remain at the natal nest and largely forego reproduction to aid the queen in rearing siblings. Socially polymorphic lineages, those containing both solitary and social species, retain the plasticity to allow intra-specific comparisons of solitary with social life. The key to understanding the transition to sociality requires a group of closely related taxa possessing broad social, taxonomic and geographic diversity. Bees provide numerous contrasts to offer insights into the origin of sociality with their range of solitary to social forms. The small carpenter bees Hymenoptera: Apidae (Xylocopinae: Ceratinini) are commonly regarded as solitary (Michener, 1974). All behaviourally classified species share a relatively simple life history. Females disperse from their natal nests and find appropriate nesting substrate. These twig-nesting bees excavate linear burrows in the cores of dead exposed pithy stems. Subsequent to burrow construction, females forage for pollen and nectar provisions that they form into a pollen mass on which they lay an egg. After provisioning and oviposition, brood cells are cappe dw ith a partition of wood pith, and the process is repeated in a serial manner along the linear nest chamber.

Life history strategy of Bradybaena similaris (Fèrussac, 1821) (Mollusca, Pulmonata, Bradybaenidae)

Bradybaena similaris (Férussac, 1821), commonly known as the Asian trampsnail, is a land snail originally native to Asia and introduced in other regions of the world through commerce in plants and produce. In Brazil, populations of this species are well established and distributed from the state of Amapá in the north to Rio Grande do Sul in the south. This land snail is easily raised in the laboratory and has been used as a biological model in studies of patterns of growth and reproduction, as well as behavioral, physiological and biochemical strategies related to starvation. In the present work, the life history strategy of B. similaris was characterized. We determined the growth, reproduction and longevity patterns of this species, and the interrelationships of these traits. Our results show that the life history of B. similaris is characterized by a combination of short life, short juvenile lifespan, early sexual maturity and few reproductive events, with a high reproductive effort in each event and high mortality shortly after the first reproduction. We conclude that there is a relationship between growth, reproduction and longevity patterns of B. similaris. This relationship is due to a differential allocation of energy between somatic growth, homeostasis and reproductive activity; which determines a life history pattern that tends to r-strategy.

How Retired Households and Households Approaching Retirement Handle Their Equity Investments in the United States

This study examines how U.S. retired households and households approaching retirement change their equity holdings over time. Applying a decomposition analysis on the repeated cross-sectional U.S. Survey of Consumer Finances from 1989 to 2004, this study presents the effects of change in population size including mortality, change in financial wealth, and change in preference on the change in aggregate financial asset share invested in equity. A formal regression-based decomposition is also provided. It was found that there is a convex relationship between age and equity holdings as a share to financial assets for the older population. In addition, the risk-taking attitude-equity holdings profile shifted upward during the period of 1989 to 2004 for the older population. It is further documented that 70% of those senior equity investors chose financing retirement and financing future liquidity as the primary saving goals. Therefore, longevity pattern plays an important role for older population to hold equity.

Intergenerational and Genealogical Approaches for the Study of Longevity in the Saguenay-Lac-St-Jean Population.

The mechanisms of longevity have been the subject of investigations for a number of years. Although the role of genetic factors is generally acknowledged, important questions persist regarding the relative impact of environmental exposures, lifestyle characteristics, and genes. The BALSAC population register offers a unique opportunity to study longevity from an intergenerational and genealogical point of view. Individuals from the Saguenay-Lac-St-Jean population who died at age 90 or older between 1950 and 1974 were selected from this database (n = 576), along with a control group of individuals born in the same period who died between 50 and 75years of age. For these subjects and controls, spouses' ages at death and parental ages at death and at their birth were investigated using regression analysis. Genealogical reconstructions were carried out for each individual, and various analyses were performed on both groups. Both fathers' and mothers' mean ages at death were significantly higher among the longer-lived cases than among controls whereas spouses' ages at death and parental ages at birth had no effect. Regression analysis confirmed the positive effect of both fathers' and mothers' age at death. Mean kinship coefficients for the parents' generations displayed significant differences, indicating that kinship was higher among subjects than controls (this effect was stronger among the oldest 10% of the subjects). Frequencies and genetic contributions of ancestors were very similar for the two groups, and none of these ancestors appeared more likely to have introduced genetic variants involved in longevity patterns in this French Canadian population.

Spatial Analysis and Surname Analysis: Complementary Tools for Shedding Light on Human Longevity Patterns

Starting from the observation that human longevity patterns show regional variations, we applied Spatial Analysis (using the Geographic Information System) and Surname Analysis to highlight the effect of the population genetic structure on such patterns. The study was carried out in Calabria, a southern Italian region which is characterized by a wide variability of geographic features (high mountains and deep valleys which created geographic isolates in the past). We identified three zones of high longevity: a male and a female longevity zone were located near the town of Cosenza (northern Calabria), while a male longevity zone was located in a mountainous and quite isolated part of the province of Reggio Calabria (southern Calabria). The latter zone was characterized by the lowest Female/Male ratio in nonagenarians observed to date. By applying surname analysis (Fisher's alpha) we found a significant negative correlation between surname abundance and index of longevity, showing that this isolated zone of male longevity presents a high level of inbreeding. On the whole, the results showed the effectiveness of spatial analysis in revealing geographical longevity patterns, and highlighted the importance of the population genetic structure in shaping such patterns.

Pre-adult development and longevity in natural populations of Lymantria dispar (Lepidoptera: Lymantriidae)

While most theoretical models for the evolution of ageing assume that duration of pre-adult development does not affect the longevity, experimental data are still controversial and inconsistent. Here we examined the short-term and long-term pattern of pre-adult development time and longevity in populations of the gypsy moth (Lymantria dispar) originating from either oak forest (Quercus petrea), a suitable, or locust-tree forest (Robinia psedoacacia), a poor habitat. Using a full-sib design, we examined the genetic correlations between traits found in larvae reared on oak or locust-tree leaves. We detected only negative and insignificant genetic correlations, except for males from the Robinia population reared on oak leaves where the correlation was negative and sig- nificant. Our results also showed that a population living 40 generations in the locust-tree forest exhibited a significantly higher lon- gevity than the Quercus population, whereas a significant difference between these two populations in pre-adult development time does not exist. The results are discussed in relation to the potential effect of stress selection in moulding the longevity of the gypsy moth.

ESTIMATING FINE_ROOT LONGEVITY OF FRAXINUS MANDSHURICAAND LARIX GMELINII USING MINI-RHIZOTRONS

Aims Fine-roots (≤2 mm diameter) are important in controlling energy and matter exchange between tree and soil. Fine-root longevity is a critical determinant of fine-root turnover and therefore carbon allocation and nutrients returned to the soil. However, little is known about variation in fine-root longevity in relation to spatial and temporal heterogeneity in availability of soil resources (such as temperature, moisture and nitrogen). How does availability of soil resources affect fine root longevity? Do different tree species, soil depths and root cohorts have different fine-root longevity in the same forest site? To answer these questions it is important to understand the fate of fine roots in soil with heterogeneous resource availability. The objectives of this study were to: 1) compare fine-root longevity between ash (Fraxinus mandshurica) and larch (Larix gmelinii) in the same site, 2) define patterns of fine-root longevity in different soil depths and elucidate the effect of availability of soil resources on fine-root longevity and 3) analyze seasonal changes of fine-root longevity for both species. Methods Mini-rhizotrons (root observation tubes) were used to estimate fine-root longevity. We established three 20 m×30 m plots in an ash and larch plantation, and installed six clear PVC (polyvinyl chloride) mini-rhizotron tubes (90 cm long × 5.5 cm inside diameter) in each plot in October 2003. From 16 April to 30 October in 2004, video images were collected from the mini-rhizotron tubes at approximately two-week intervals and analyzed with an image analysis system (RooTracker software). We compared differences in longevity between tree species, soil depths and seasonal root cohorts using cumulative survival rate and median root longevity (MRL) of fine roots by Kaplan-Meier methods in survival analysis. Important findings Cumulative survival rate of fine roots decreased gradually with time. Survivorship curves showed that cumulative survival rate of fine roots in ash was significantly higher than that in larch (p 0.001 ); MRL was 111±7 d in ash and 77±4 d in larch. Higher fine root mortality was found in 0-20 cm soil, as MRL was 62±11 d for larch and 111±6 d for ash, contrasting with 95±11 d for larch and 124±20 d for ash in deep soil. This study also indicated longer lifespans of fine roots produced in summer (82±6 d for larch) than spring (47±13 d). Similar seasonal pattern was found for ash. Fine-root longevity was different between tree species due to different root genetics, physiology and architecture. High soil temperature and high N content can decrease fine root longevity. In summer, photosynthates are allocated to roots and fine roots grow rapidly and have increased longevity. Our results suggested that fine-root longevity is correlated with genetics of the species, physiological status and soil resource availability.

AGEING AND METABOLISM OF MYTILUS EDULIS: POPULATIONS FROM VARIOUS CLIMATE REGIMES

The aim of this study is to elucidate the impact of age and temperature on metabolic key parameters (respiration rate and mitochondrial marker enzymes) controlling maximal size and longevity in the blue mussel Mytilus edulis L. from geographically separated populations of Northern European seas. Mussels from the Barents Sea attain similar maximal sizes as animals from the warmer North Sea. Young animals (<5 y) grow faster in the North Sea, however, inshore Barents Sea mussels grow rapidly even at advanced age. The slowest growth rates were found in a population exposed to strong wave action in the Barents Sea. Respiration rates followed the same age dependent pattern in mussels from all studied populations with low respiration rates in the youngest specimens followed by a rapid increase and then a gradual decline to nearly constant values in the oldest animals. When compared at a common temperature, metabolic rates only of young blue mussels (<7–8 y) are cold compensated with maximal respiration in the most Northern populations. Cold compensated metabolic activities in mussels from Northern populations may support similar patterns of maximal body size and longevity as in the more temperate Southern population.

Reproductive protein protects functionally sterile honey bee workers from oxidative stress

Research on aging shows that regulatory pathways of fertility and senescence are closely interlinked. However, evolutionary theories on social species propose that lifelong care for offspring can shape the course of senescence beyond the restricted context of reproductive capability. These observations suggest that control circuits of aging are remodeled in social organisms with continuing care for offspring. Here, we studied a circuit of aging in the honey bee (Apis mellifera). The bee is characterized by the presence of a long-lived reproductive queen caste and a shorter-lived caste of female workers that are life-long alloparental care givers. We focus on the role of the conserved yolk precursor gene vitellogenin that, in Caenorhabditis elegans, shortens lifespan as a downstream element of the insulin/insulin-like growth factor signaling cascade. Vitellogenin protein is synthesized at high levels in honey bee queens and is abundant in long-lived workers. We establish that vitellogenin gene activity protects worker bees from oxidative stress. Our finding suggests that one mechanistic explanation for patterns of longevity in bees is that a reproductive regulatory pathway has been remodeled to extend life. This perspective is of considerable relevance to research on longevity regulation that builds largely on inference from solitary model species.

Parental Investment, Late Reproduction, and Increased Reserve Capacity Are Associated with Longevity in Humans

Throughout the living world trade-offs between reproductive success and longevity have been observed. In general, two extremes of life history patterning are reported, r- and K-selected species. The latter tend toward larger body sizes, few offspring from any one pregnancy, few offspring over the female reproductive span, longer life spans, and greater parental investment (PI: all efforts and expenses associated with the production, gestation, post-natal care, feeding, and protection of young) (e.g., whales, elephants, hominids). r-selected species tend toward smaller body size, multiple births/litters per pregnancy, female production of many gametes and offspring over the life span, and low levels of PI (e.g., most plants, insects, mice). These differences have significant influences on physiological variation among human populations. Across human samples, reproductive success (RS: the number of offspring successfully birthed and reared to reproductive age) has been reported to vary positively, negatively, and not at all with longevity of women. This complexity may be in part due to the fact that both early-life and late-life fecundity are associated with longevity in women, while total parity seems a poor gauge of female longevity in humankind. Large variations in associations of RS with longevity in women suggest that multiple factors may confound this association. One confounding factor is that among women, RS is largely determined not by fecundity, but by the quality of PI available to offspring. Among modern humans, PI is more complex, longer lasting (both relatively and absolutely), and extensive than for any other mammal. This suggests that modern human life history is a reflection of the co-evolution of longevity and extensive PI as part of our species' biocultural evolution. The need for long-term PI has greatly shaped human physiological variation and patterns of longevity.

Do deviants live longer? Morphology and longevity in trachyleberidid ostracodes

Persistent fossil taxa contravene paradigms of evolution: pervasive morphological change and taxic turnover. Comparative studies of taxic duration have often been approached from biogeographic, climatic, and ecological perspectives, with a focus on process. Here I use a mor- phological approach to study the pattern of longevity of a large family of marine living and fossil podocopid ostracodes, Trachyleberididae sensu lato. I test if geologically longer-lived genera are collectively morphologically more deviant from a group mean than their shorter-lived relatives by using both discrete morphological data and outline data. I discovered that long-lived genera are in general not significantly more or less morphologically deviant from the average morphology than their shorter-lived relatives. However, I found that contemporaneous subsets of long-lived trachyleberidids are often at least marginally significantly more deviant in discrete morphology than shorter-lived ones, especially in external morphology. No significant patterns of association between morphological deviation and durations in other subdivisions of the data emerged (i.e., whole data set, birth cohorts, groups of morphological characters, and outline data using both Fou- rier analysis and eigenshape analysis). This is in contrast to a previous finding that long-lived gen- era of crinoids within orders are often morphologically less deviant than their shorter-lived rela- tives than expected by chance.

GEOGRAPHIC VARIATION IN DIAPAUSE INCIDENCE, LIFE‐HISTORY TRAITS, AND CLIMATIC ADAPTATION INDROSOPHILA MELANOGASTER

In Drosophila melanogaster, exposure of females to low temperature and shortened photoperiod can induce the expression of reproductive quiescence or diapause. Diapause expression is highly variable within and among natural populations and has significant effects on life-history profiles, including patterns of longevity, fecundity, and stress resistance. We hypothesized that if diapause expression is associated with overwintering mechanisms and adaptation to temperate environments, the frequency of diapause incidence would exhibit a latitudinal cline among natural populations. Because stress resistance and reproductive traits are also clinal in this species, we also examined how patterns of fecundity and longevity varied with geography and how stress resistance and associated traits differed constitutively between diapause and nondiapause lines. Diapause incidence was shown to vary predictably with latitude, ranging from 35% to 90% among natural populations in the eastern United States Survivorship under starvation stress differed between diapause and nondiapause lines; diapause phenotypes were also distinct for total body triglyceride content and the developmental distribution of oocytes in the ovary following stress exposure. Patterns of longevity, fecundity, and ovariole number also varied with geography. The data suggest that, for North American populations, diapause expression is functionally associated with overwintering mechanisms and may be an integral life-history component in natural populations.

Maize and Oat Antixenosis and Antibiosis Against &lt;I&gt;Delphacodes kuscheli&lt;/I&gt; (Homoptera: Delphacidae), Vector of “Mal de Rio Cuarto” of Maize in Argentina

"Mal de Rio Cuarto" (MRC) is the most important virus disease of maize, Zea mays L., in Argentina. Several maize lines show different levels of resistance to MRC in the field; however, no studies have been conducted to investigate resistance mechanisms against its insect vector, Delphacodes kuscheli Fennah (Homoptera: Delphacidae). Oat, Avena spp., is the main overwintering host of D. kuscheli and main source of populations that infest maize. Although oat varieties resistant to the greenbug, Schizaphis graminum (Rondani) (Homoptera: Aphididae) are commercially available, their effect on D. kuscheli is unknown. We conducted laboratory experiments to test for the presence of antixenosis and antibiosis resistance mechanisms on six maize lines with different levels of field resistance to MRC, and seven commercial oat cultivars that include two S. graminum-resistant varieties. We did not find antibiotic effects of maize lines on D. kuscheli longevity and survivorship patterns, but we obtained antixenotic effects from the LP2 line (field moderate) due to reduced settling preference and feeding. Oat 'Bonaerense Payé and 'Suregrain INTA' showed both antixenosis and antibiosis, with significantly less settling preference, oviposition in the no-choice test, and reduced total fecundity in comparison with the other varieties studied. The S. graminum-resistant 'Boyera F. A.' and 'Tambera F. A.' did not showed a consistent pattern of resistance versus D. kuscheli across all experiments. Our results indicate the presence of potential sources of insect resistance in the maize lines and oat cultivars tested that may be used in MRC integrated pest management programs.

A Correction to the Perspective Titled "Misdirection on the Road to Shangri-La" by Olshansky et al.

Will life expectancy in the United States rise or fall in this century? The implications of either scenario are far reaching. We contend that the rise of childhood obesity in the United States in the past three decades has been so dramatic that it will soon lead to higher than expected death rates at middle ages and a possible decline in life expectancy by midcentury. The most detrimental health and longevity effects will not be seen for decades--a phenomenon that cannot be detected by current methods used to forecast life expectancy or estimate the number of deaths currently attributable to obesity. This scenario contrasts sharply with the views of mathematical demographers who generate forecasts by relying on the assumption that the U.S. pattern of longevity will follow that of other longer lived nations and on the extrapolation of historical trends in life expectancy into the future.

Misdirection on the Road to Shangri-La

Will life expectancy in the United States rise or fall in this century? The implications of either scenario are far reaching. We contend that the rise of childhood obesity in the United States in the past three decades has been so dramatic that it will soon lead to higher than expected death rates at middle ages and a possible decline in life expectancy by midcentury. The most detrimental health and longevity effects will not be seen for decades--a phenomenon that cannot be detected by current methods used to forecast life expectancy or estimate the number of deaths currently attributable to obesity. This scenario contrasts sharply with the views of mathematical demographers who generate forecasts by relying on the assumption that the U.S. pattern of longevity will follow that of other longer lived nations and on the extrapolation of historical trends in life expectancy into the future.

Postnatal ontogeny, population structure, and extinction of the giant moa Dinornis

Recent reinterpretation of the giant moa Dinornis as consisting of two sexually dimorphic allospecies permits thorough site-by-site investigation of the ontogeny and population biology of this genus. Analysis of subadult skeletal material from natural swamp sites in the North and South Islands of New Zealand forms the basis for recognition of growth series for each long bone element, characterized by sequential formation of fossulae in the femur and fusion of bones in the tibiotarsus and tarsometatarsus. Femora reached progressive developmental stages more rapidly than the other long bones, but all three elements reached maturity at about the same time. Patterns of bone fusion in Dinornis are more similar to those in Apteryx than in Struthio, and kiwi are recognized as a suitable developmental analog for interpreting moa ontogeny. Samples from Bell Hill Vineyard Swamp (South Island) and Makirikiri swamp (North Island) are interpreted as representing autochthonous moa populations; comparison with stages of kiwi long bone development suggests that Dinornis at these sites had high adult survivorship in strongly K-selected populations, with 72.5-87.3% of individuals having achieved adult body mass, and 55.9-78.2% being sexually mature. The pattern of low fecundity and probable high longevity in both Dinornis species suggests that populations were vulnerable to loss of adults, primarily through hunting, rather than as a result of habitat destruction.