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.

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.

scholarly journals Who Belongs? How Status Influences the Experience of Gemeinschaft

2019 ◽  
Vol 82 (1) ◽  
pp. 31-50
Author(s):  
Cary Beckwith
Keyword(s):  
Social Status ◽  
Small Groups ◽  
High Status ◽  
Cumulative Advantage ◽  
Status Hierarchy ◽  
High Ranking ◽  
Naturally Occurring ◽  
Group Life ◽  
Using Data

Belonging is a central human aspiration, one that has drawn attention from sociologists and social psychologists alike. Who is likely to realize this aspiration? This paper addresses that question by examining how “we-feeling”—the experience of gemeinschaft—is distributed within small groups. Previous research has argued that the feeling of belonging is positively related to a person’s social status through a cumulative advantage process. But high status can recast the responsibilities of group life as burdens if a person regards them as incongruent with his or her rank, and this can dim one’s feelings toward the group. This paper proposes that a “high-status penalty” diminishes we-feeling for high-ranking individuals, thereby concentrating we-feeling in the middle of a status hierarchy. It tests this theory using data from the Urban Communes Project, a survey of 60 naturally occurring communities. The findings suggest that status-incongruent responsibilities can suppress the benefits of status at the top of a hierarchy.

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.

scholarly journals The evolution of growth rates on an expanding range edge

2009 ◽  
Vol 5 (6) ◽  
pp. 802-804 ◽  
Author(s):  
Ben L. Phillips
Keyword(s):  
Life History ◽  
Population Growth ◽  
Growth Rates ◽  
Life History Theory ◽  
Common Garden ◽  
Individual Growth ◽  
Dispersal Ability ◽  
Invasion Front ◽  
Range Edge ◽  
Theoretical Predictions

Individuals in the vanguard of a species invasion face altered selective conditions when compared with conspecifics behind the invasion front. Assortment by dispersal ability on the expanding front, for example, drives the evolution of increased dispersal, which, in turn, leads to accelerated rates of invasion. Here I propose an additional evolutionary mechanism to explain accelerating invasions: shifts in population growth rate ( r ). Because individuals in the vanguard face lower population density than those in established populations, they should (relative to individuals in established populations) experience greater r -selection. To test this possibility, I used the ongoing invasion of cane toads ( Bufo marinus ) across northern Australia. Life-history theory shows that the most efficient way to increase the rate of population growth is to reproduce earlier. Thus, I predict that toads on the invasion front will exhibit faster individual growth rates (and thus will reach breeding size earlier) than those from older populations. Using a common garden design, I show that this is indeed the case: both tadpoles and juvenile toads from frontal populations grow around 30 per cent faster than those from older, long established populations. These results support theoretical predictions that r increases during range advance and highlight the importance of understanding the evolution of life history during range advance.

Differentiation in juvenile growth and bimodality patterns between northern and southern populations of Atlantic salmon (Salmo salar L.)

1994 ◽  
Vol 72 (9) ◽  
pp. 1603-1610 ◽  
Author(s):  
Alfredo G. Nicieza ◽  
Felipe G. Reyes-Gavilán ◽  
Florentino Braña
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Growth Rates ◽  
Individual Growth ◽  
Late Winter ◽  
Southern Population ◽  
Northern Spain ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Atlantic Salmon ◽  
Modal Group

Juvenile Atlantic salmon, Salmo salar, from two contrasting populations that had been reared under identical conditions differed in freshwater growth rates and the development of bimodality in length–frequency distributions. Segregation by size started at least a month earlier in the northern (River Shin, northern Scotland) than in the southern population (River Narcea, northern Spain). Northern fish initially grew faster and entered the upper modal group at a larger size (about 100 mm) than did southern fish (about 90 mm). However, the percentage of fish in the upper modal group was greater for the southern population and they grew fastest over winter and during the spring leading up to smolting, and were larger at the smolt stage. By late winter, the individual growth rates of upper modal fish were inversely correlated with their body length in December. These results suggest the existence of genetic differences between populations in the expression of growth bimodality in juvenile Atlantic salmon. This may indicate that size and growth rate thresholds determining the developmental pathway associated with age at smolt metamorphosis may vary between populations as a function of both smolt size and expected growth opportunity during winter and spring.

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