Annual life-history variation in the striped plateau lizard, Sceloporus virgatus

1996 ◽  
Vol 74 (11) ◽  
pp. 2025-2030 ◽  
Author(s):  
Geoffrey R. Smith
Keyword(s):  
Life History ◽  
Body Mass ◽  
Growth Rates ◽  
Individual Growth ◽  
First Year ◽  
Life History Variation ◽  
Demographic Traits ◽  
Sceloporus Virgatus ◽  
One Year ◽  
Annual Life History

I studied temporal variation in life-history and demographic traits of a population of striped plateau lizards, Sceloporus virgatus, over 3 years in the Chiricahua Mountains of southeastern Arizona. The 3 years of the study varied in precipitation and arthropod (prey) abundance, but the 2 years for which data were available did not differ in the amount of time potentially available for lizard activity. Individual growth, gain in body mass, and adult survivorship varied among years, the year of lowest precipitation levels (1994) having the slowest growth rates (0.099 mm/d) and gain in body mass (0.008 g/d) and the lowest adult survivorship (0.28), and the year of highest precipitation levels (1992) having the fastest growth rates (0.117 mm/d) and gain in body mass (0.029 g/d) and the highest adult survivorship (0.40). The proportion of first-year females that reproduced, juvenile survivorship, sex ratio, and age structure of the population did not differ among years. Individuals that grew faster (or slower) than expected from their body size in one year grew faster (or slower) than expected the next year. Survivors (both male and female) did not grow faster than nonsurvivors. Precipitation appears to be the strongest proximate factor influencing annual life-history traits in this population, probably because of its influence on arthropod abundance.

The effects of social status on life-history variation in juvenile salmon

1990 ◽  
Vol 68 (12) ◽  
pp. 2630-2636 ◽  
Author(s):  
Neil B. Metcalfe ◽  
Felicity A. Huntingford ◽  
John E. Thorpe ◽  
Colin E. Adams
Keyword(s):  
Life History ◽  
Social Status ◽  
Growth Rates ◽  
Individual Growth ◽  
Laboratory Population ◽  
High Status ◽  
Life History Variation ◽  
High Ranking ◽  
Clear Cut ◽  
Modal Group

Under good growing conditions, juvenile Atlantic salmon metamorphose into the migratory smolt stage at 1+ or 2+ years of age. The life-history decision on whether or not to migrate at 1+ years is made in July–August of the previous year. After this time, populations develop a bimodal size distribution, the larger fish (upper modal group) being the 1+ smolts and the lower modal group being fish that will smolt at 2+. Fish of high social status are more likely to become 1+ smolts. We examined the causal nature of this relationship by manipulating status within a laboratory population of sibling fish. The absolute status of individual fish was estimated within 2 weeks of first feeding. Relative status was then manipulated by dividing the population into two, half containing the fish with the highest absolute status (high ranking) and the remaining half of fish of lowest absolute status (low ranking). The status of individually marked fish was then determined within each of the two groups. Individual growth rates were monitored until smolting strategies were apparent. There was a complete overlap in the sizes of subsequent upper and lower modal group parr in early June, but from late June onwards fish in the upper modal group grew faster. The high- and low-ranking groups did not differ either in mean growth rates or in the proportions of fish adopting the alternative smolting strategies. However, they differed in the factors that influenced an individual's developmental strategy: within the high-ranking group, relative social status in June was a significant predictor of whether a fish would smolt aged 1+, whereas length at that time was not. In contrast, no relationship between status and smolting strategy was found in the low-ranking group, where differences in status were less clear-cut and had less influence on growth. Instead, age of smolting could be predicted from early growth rate. These results demonstrate that the influence of status on smolting depends on the extent to which fish of high status suppress the growth of those lower in the hierarchy.

scholarly journals The impacts of body mass on immune cell concentrations in birds

2020 ◽  
Author(s):  
Emily Cornelius Ruhs ◽  
Lynn B. Martin ◽  
Cynthia J. Downs
Keyword(s):  
Life History ◽  
Body Mass ◽  
Immune Cell ◽  
Disease Risk ◽  
Cell Types ◽  
Biological Traits ◽  
Extensive Literature ◽  
Life History Variation ◽  
Immune Systems ◽  
Scaling Hypothesis

ABSTRACTBody mass affects many biological traits, but its impacts on immune defenses are fairly unknown. Recent research on mammals found that neutrophil concentrations scaled hypermetrically with body mass, a result not predicted by any existing theory. Although this mammalian model might predict how leukocyte concentrations scale with body mass in other vertebrates, vertebrate classes are distinct in many ways that might affect their current and historic interactions with parasites and hence the evolution of their immune systems. Subsequently, here, we asked which existing scaling hypothesis best-predicted relationships between body mass and lymphocyte, eosinophil, and heterophil concentrations—the avian functional equivalent of neutrophils—among >100 species of birds. We then examined the predictive power of body mass relative to life-history variation, as an extensive literature indicates that the scheduling of key life events has influenced immune system variation among species. Finally, we ask whether these scaling patterns differ from the patterns we observed in mammals. We found that an intercept-only model best-explained lymphocyte and eosinophil concentrations among birds; body mass minimally influenced these two cell types. For heterophils, however, body mass explained over 30% of the variation in concentrations among species, much more than life-history variation (~8%). As with mammalian neutrophils, avian heterophils scaled hypermetrically (b=0.19 ± 0.05), but significantly steeper than mammals (~1.5x). As such, we discuss why birds might require more broadly-protective cells compared to mammals of the same body size. Body mass appears to have strong influences on the architecture of immune systems, which could impact host-parasite coevolution and even zoonotic disease risk for humans.

THE INFLUENCE OF REPRODUCTION ON BODY WEIGHT IN WOMEN

1957 ◽  
Vol 15 (4) ◽  
pp. 393-409 ◽  
Author(s):  
THOMAS McKEOWN ◽  
R. G. RECORD
Keyword(s):  
Body Weight ◽  
Early Pregnancy ◽  
Growth Rates ◽  
First Year ◽  
Weight Changes ◽  
Present Communication ◽  
Small Loss ◽  
One Year ◽  
First Year Of Life

SUMMARY 1. Data recorded in respect of all women whose children were born in a county borough during one year included the weight at the first antenatal examination (adjusted according to the number of days by which it preceded or followed the 124th day of gestation), and at 3, 6, 9, 12 and 24 months after delivery. The present communication is concerned with the influence of reproduction on body weight. 2. It is estimated that between conception and 24 months after birth women gained, on the average, approximately 6·6 lb. This is about 5 lb. more than would have been added in the same period if they had not been pregnant. Reasons are given for believing that these estimates may be a little low, probably not by more than 1 lb. 3. The increase in weight occurred mainly during pregnancy. From 3 months after delivery changes in mean weight were relatively small: a loss of 1·8 lb. between 3 and 12 months, and a gain of 0·6 lb. between 12 and 24 months. 4. The increment in mean weight between conception and 24 months increased slightly with parity, and, less certainly, with age. The most striking association with these variables occurred between 3 and 12 months after birth, when the proportion of women who gained weight decreased with increasing parity and increased with increasing age (Fig. 5). It is suggested that this relationship is probably attributable to an association between age and parity and social circumstances, and it is shown that the same trend was exhibited by the growth rates of the offspring of the same mothers during the first year of life (Fig. 6). 5. Lactation had little influence on mean weight. It resulted in a small loss during the period of lactation, but its effect was almost eliminated at 24 months after delivery (Fig. 7). 6. During the various intervals between early pregnancy and 24 months after delivery weight changes appear to be continuously distributed (Fig. 1). The constants of the distributions are given (Table 4).

scholarly journals Production Method Affects Tree Establishment in the Landscape

1996 ◽  
Vol 14 (2) ◽  
pp. 81-87 ◽  
Author(s):  
Edward F. Gilman ◽  
Richard C. Beeson
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Production Method ◽  
First Year ◽  
Irrigation Frequency ◽  
Tree Establishment ◽  
B Trees ◽  
Soil Volume ◽  
One Year ◽  
Plastic Containers

Abstract Trunk growth rates one year after transplanting 5 cm (2 in) caliper laurel oak (Quercus laurifolia Michx.) from above-ground plastic containers, from in-ground fabric containers or from the field (B&B) matched or exceeded growth rates before transplanting. Growth rates for all three treatments were similar seven months after transplanting. Shoots on field-grown trees grew more in the first year after transplanting than those from fabric or plastic containers. Roots removed at the time of digging were completely replaced on field and fabric container trees six months after transplanting. One year after transplanting, roots occupied the same soil volume as just prior to transplanting. Trees from plastic containers regenerated roots slower than B&B trees or those from fabric containers. When irrigation frequency was reduced 14 weeks after transplanting (WAT), trees from plastic containers were water stressed more (had more negative xylem potential) than B&B or fabric container trees. Growth rates of East Palatka holly (Ilex × attenuata Ashe. ‘East Palatka’) responded similarly to laurel oak; however hollies took longer to establish roots into landscape soil and took longer for the trunk growth rate to match that on trees prior to transplanting.

Life-history variation among populations of Canadian Toads in Alberta, Canada

2005 ◽  
Vol 83 (11) ◽  
pp. 1421-1430 ◽  
Author(s):  
Brian R Eaton ◽  
Cynthia A Paszkowski ◽  
Kent Kristensen ◽  
Michelle Hiltz
Keyword(s):  
Life History ◽  
Growth Rates ◽  
Life History Traits ◽  
Age At Maturity ◽  
Life History Variation ◽  
Size At Age ◽  
Almost All ◽  
Conservation Plans ◽  
Toad Bufo ◽  
Latitudinal Range

Development of appropriate conservation plans relies on life-history information and how life-history traits vary across populations of a species. Such data are lacking for many amphibians, including the Canadian Toad (Bufo hemiophrys Cope, 1886). Here we use skeletochronology to estimate size at age, growth rates, age at maturity, and longevity of toads from nine populations along a latitudinal gradient in Alberta, Canada. Size of individual toads within each year class was highly variable, but age and size (measured as snout-to-urostyle length) were significantly related for almost all populations. The largest individuals were found in the southern-most population, while the smallest toads were found in three populations from the middle of the latitudinal range studied. Growth rates were highest in the southern-most population and lowest at the three populations with relatively small individuals. Maximum age was from 7 to 12 years for the populations sampled. The oldest individuals were found in populations in the middle of the latitudinal range sampled; toads in these populations were smaller than those in all other populations. Age at maturity was 1 year old for males and 2 years old for females in most populations. This study shows that some life-history traits exhibit significant variation between Canadian Toad populations, suggesting that effective conservation of this species will need to include population or area-specific management.

Applications

2021 ◽  
pp. 153-172
Author(s):  
Jeffrey A. Hutchings
Keyword(s):  
Life History ◽  
Maximum Size ◽  
Individual Growth ◽  
Natural Mortality ◽  
Negative Consequences ◽  
Age At Maturity ◽  
Life History Variation ◽  
Vulnerability Assessments ◽  
Individual Growth Rate ◽  
Declining Species

By affecting age-specific survival and fecundity, human-induced disturbances affect life history. This has potential to affect r max with negative consequences for species viability and persistence. Several types of assessments are used to classify vulnerability to extinction, exploitation, and climate change. When information on r max is unavailable, vulnerability assessments often rely on life-history correlates of r max. These have included generation time, age at maturity, maximum size, longevity, fecundity, natural mortality, and individual growth rate. Empirical research indicates that links with r max are strong for some traits, such as age at maturity and body size, but weak for others, such as fecundity. In addition to assessments of declining species, efforts have been made to identify life-history correlates of the rate and uncertainty in species recovery. Persistence and stability can be strengthened by the magnitude of life-history variation. The greater the variability in life history within and among, the greater the resistance and resilience of populations and species.

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