Life history variation in Celleporella hyalina (Bryozoa)

1986 ◽  
Vol 228 (1251) ◽  
pp. 127-132 ◽  
Keyword(s):  
Growth Rate ◽  
Life History ◽  
Sex Ratio ◽  
Water Flow ◽  
Reproductive Output ◽  
Life History Strategy ◽  
Colony Growth ◽  
Allocation Of Resources ◽  
Life History Variation ◽  
Male And Female

In colonies of the cheilostome bryozoan Celleporella hyalina (L.), water flow regime has a significant effect on colony growth rate and, indirectly, on the number of reproductive zooids produced. Higher growth rates occur under conditions of higher water flow. Sex ratio and reproductive output are not, however, significantly affected. Colonies of different genotypes show significant differences in their reproductive versus somatic investment, and in their allocation of resources to male and female functions. There is therefore genetically based variation in life history strategy within the population of colonies. This variation may reflect limitation of normalizing selection imposed by microenvironmental variability.

scholarly journals The impact of sex ratio and economic status on local birth rates

2013 ◽  
Vol 9 (2) ◽  
pp. 20130027 ◽  
Author(s):  
A. Chipman ◽  
E. Morrison
Keyword(s):  
Life History ◽  
Sex Ratio ◽  
Economic Status ◽  
Life History Strategy ◽  
Reproductive Behaviour ◽  
Female Competition ◽  
Birth Rates ◽  
Economically Deprived ◽  
Human Mating ◽  
The Impact

Human mating and reproductive behaviour can vary depending on various mechanisms, including the local sex ratio. Previous research shows that as sex ratios become female-biased, women from economically deprived areas are less likely to delay reproductive opportunities to wait for a high-investing mate but instead begin their reproductive careers sooner. Here, we show that the local sex ratio also has an impact on female fertility schedules. At young ages, a female-biased ratio is associated with higher birth rates in the poorest areas, whereas the opposite is true for the richest areas. At older ages, a female-biased ratio is associated with higher birth rates in the richest, but not the poorest areas. These patterns suggest that female–female competition encourages poorer women to adopt a fast life-history strategy and give birth early, and richer women to adopt a slow life-history strategy and delay reproduction.

Life History Strategies

2018 ◽  
pp. 95-126
Author(s):  
Marco Del Giudice
Keyword(s):  
Life History ◽  
Individual Differences ◽  
Life History Theory ◽  
Human Life ◽  
Life History Strategy ◽  
Current Theory ◽  
Life History Strategies ◽  
Extended Model ◽  
Life History Variation ◽  
Basic Model

The chapter introduces the basics of life history theory, the concept of life history strategy, and the fast–slow continuum of variation. After reviewing applications to animal behavior and physiology, the chapter reviews current theory and evidence on individual differences in humans as manifestations of alternative life history strategies. The chapter first presents a “basic model” of human life history–related traits, then advances an “extended model” that identifies multiple cognitive-behavioral profiles within fast and slow strategies. Specifically, it is proposed that slow strategies comprise prosocial/caregiving and skilled/provisioning profiles, whereas fast strategies comprise antisocial/exploitative and seductive/creative profiles. The chapter also reviews potential neurobiological markers of life history variation and considers key methodological issues in this area.

Seaweed-associated animal communities in the Firth of Clyde, with special reference to the population biology of the amphipod Hyale nilssoni (Rathke)

1986 ◽  
Vol 90 ◽  
pp. 271-286
Author(s):  
P. G. Moore
Keyword(s):  
Growth Rate ◽  
Life History ◽  
Sex Ratio ◽  
Seasonal Changes ◽  
Population Biology ◽  
Dynamic Equilibrium ◽  
Present Knowledge ◽  
New Work ◽  
Animal Communities ◽  
Breeding Status

SynopisPresent knowledge of animal communities associated with the algae of the Firth of Clyde is briefly reviewed. New work is presented on Hyale nilssoni (Rathke), the commonest amphipod inhabiting high littoral seaweeds, which describes the life-history characteristics over three years of a population associated with Pelvetia. Seasonal changes in growth rate, sex ratio and breeding status are described. Fecundity is investigated and data on brood and egg sizes compared with populations from other latitudes. The dynamic equilibrium between the grazer (Hyale) and the grazed (Pelvetia) is described.

Comparison of growth physiology, morphology, and smolt indicators in juvenile Lake Superior brook trout (Salvelinus fontinalis) strains in reference to life history variation

2012 ◽  
Vol 69 (10) ◽  
pp. 1596-1609 ◽  
Author(s):  
Carla A.V. Serfas ◽  
Anna Varian ◽  
Rachel Holman ◽  
Lindsey M. Watch ◽  
Jesse Karner ◽  
...  
Keyword(s):  
Life History ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Lake Superior ◽  
Morphological Variability ◽  
Life History Strategy ◽  
Growth Potential ◽  
Relative Mass ◽  
Life History Variation ◽  
Rate Condition

Lake Superior supports fluvial, adfluvial, and lacustrine populations of brook trout ( Salvelinus fontinalis ). Adfluvial and lacustrine populations (termed coasters) are known for their large size and are coveted by anglers; however, little is known about their migratory habits or physiology. This study examined physiology and morphology of age 1+ lacustrine, adfluvial, and fluvial strains of brook trout in a laboratory setting. All strains in the study grew; however, there were no differences in growth rate, condition, relative mass, morphology, white muscle metabolic enzymes, or gill Na+,K+-ATPase that clearly associated with putative life history strategy. Both thyroxine and triiodothyronine varied over the study period, and the fluvial (resident) strain consistently showed lower thyroid hormone levels than the three coaster strains. We conclude that the populations compared differed at the strain level, but do not show physiological or morphological variability that clearly associates with life history strategy; the exception was that populations demonstrating the coaster phenotype had increased concentrations of plasma thyroid hormones, which may be linked to growth potential or other coaster-related characteristics such as migration.

Trait-Based Approach to Fish Ecology

2019 ◽  
pp. 150-160
Author(s):  
Ken H. Andersen
Keyword(s):  
Growth Rate ◽  
Life History ◽  
Life History Strategy ◽  
Somatic Growth ◽  
Population Level ◽  
Historical Background ◽  
Life History Strategies ◽  
Asymptotic Size ◽  
Current State ◽  
Investment In Reproduction

This chapter proposes a shortlist of fish “master” traits and connects these traits to classic life-history strategy thinking. First, it sets the historical background for the current state-of-the-art thinking about fish life history strategies. From there, the chapter explains that the main axes of variation between fish species can be captured by three traits: the asymptotic size; the growth rate coefficient; and the adult–offspring mass ratio strategy. Together, these three traits determine the central demographic parameters: somatic growth rate, investment in reproduction, age at maturation, survival to maturation, mortality, and so on, and from there follows population-level quantities like population growth rate, population structure, fitness, and selection responses. The chapter concludes with a reflection on the trait-based approach and compares it to other methods of assessment.

The life history, nymphal growth rates, and feeding habits of Siphlonisca aerodromia Needham (Ephemeroptera: Siphlonuridae) in Maine

1986 ◽  
Vol 64 (2) ◽  
pp. 427-430 ◽  
Author(s):  
K. Elizabeth Gibbs ◽  
Terry M. Mingo
Keyword(s):  
Growth Rate ◽  
Life History ◽  
Sex Ratio ◽  
Growth Rates ◽  
Feeding Habits ◽  
Main Channel ◽  
Head Width ◽  
Snow Melt ◽  
Animal Material ◽  
Nymphal Growth

Siphlonisca aerodromia Needham has a univoltine life history in Maine. Adults emerge in late May or early June. Each female contains about 394 large (0.46 mm long) eggs covered with coiled fibers that anchor the eggs to the substrate. Eggs are deposited in the main channel of the stream and small nymphs appear in January. Nymphal growth rate (GHW) was expressed as a percent per day increase in head width. Initially nymphs feed on detritus and grow slowly (GHW = 0.28–0.79) at water temperatures near 0 °C. Following snow melt, the nymphs move into the adjacent Carex floodplain. Here, water temperature increases, animal material, in the form of mayfly nymphs, becomes increasingly common in the diet, and growth rate increases (GHW = 2.13–2.89). The sex ratio of nymphs collected in May and June was 1:1.8 (male:female).

scholarly journals Life‐history variation of a neotropical thrush challenges food limitation theory

2005 ◽  
Vol 272 (1564) ◽  
pp. 769-773 ◽  
Author(s):  
Valentina Ferretti ◽  
Paulo E Llambías ◽  
Thomas E Martin
Keyword(s):  
Growth Rate ◽  
Life History ◽  
Clutch Size ◽  
Life History Traits ◽  
Food Limitation ◽  
Life History Evolution ◽  
Traditional Theory ◽  
Life History Variation ◽  
Nestling Growth ◽  
Parental Feeding

Since David Lack first proposed that birds rear as many young as they can nourish, food limitation has been accepted as the primary explanation for variation in clutch size and other life‐history traits in birds. The importance of food limitation in life-history variation, however, was recently questioned on theoretical grounds. Here, we show that clutch size differences between two populations of a neotropical thrush were contrary to expectations under Lack's food limitation hypothesis. Larger clutch sizes were found in a population with higher nestling starvation rate (i.e. greater food limitation). We experimentally equalized clutches between populations to verify this difference in food limitation. Our experiment confirmed greater food limitation in the population with larger mean clutch size. In addition, incubation bout length and nestling growth rate were also contrary to predictions of food limitation theory. Our results demonstrate the inability of food limitation to explain differences in several life-history traits: clutch size, incubation behaviour, parental feeding rate and nestling growth rate. These life-history traits were better explained by inter‐population differences in nest predation rates. Food limitation may be less important to life history evolution in birds than suggested by traditional theory.

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