The relationship between offspring size and fitness: integrating theory and empiricism

Ecology ◽  
2013 ◽  
Vol 94 (2) ◽  
pp. 315-324 ◽  
Author(s):  
Njal Rollinson ◽  
Jeffrey A. Hutchings
Keyword(s):  
Offspring Size ◽  
The Relationship

scholarly journals Trade-off between offspring mass and number: the lightest offspring bear the costs

2020 ◽  
Vol 16 (2) ◽  
pp. 20190707
Author(s):  
Joanie Van de Walle ◽  
Andreas Zedrosser ◽  
Jon E. Swenson ◽  
Fanie Pelletier
Keyword(s):  
Life History ◽  
Litter Size ◽  
Phenotypic Variation ◽  
Reproductive Strategy ◽  
Life History Theory ◽  
Brown Bear ◽  
Offspring Size ◽  
Trade Off ◽  
The Relationship

Life-history theory predicts a trade-off between offspring size and number. However, the role of intra-litter phenotypic variation in shaping this trade-off is often disregarded. We compared the strength of the relationship between litter size and mass from the perspective of the lightest and the heaviest yearling offspring in 110 brown bear litters in Sweden. We showed that the mass of the lightest yearlings decreased with increasing litter size, but that the mass of the heaviest yearling remained stable, regardless of litter size. Consistent with a conservative reproductive strategy, our results suggest that mothers maintained a stable investment in a fraction of the litter, while transferring the costs of larger litter size to the remaining offspring. Ignoring intra-litter phenotypic variation may obscure our ability to detect a trade-off between offspring size and number.

scholarly journals Why does offspring size affect performance? Integrating metabolic scaling with life-history theory

2015 ◽  
Vol 282 (1819) ◽  
pp. 20151946 ◽  
Author(s):  
Amanda K. Pettersen ◽  
Craig R. White ◽  
Dustin J. Marshall
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Maternal Investment ◽  
Offspring Size ◽  
Metabolic Efficiency ◽  
Metabolic Scaling ◽  
And Performance ◽  
The Relationship ◽  
General Explanation ◽  
Better Than

Within species, larger offspring typically outperform smaller offspring. While the relationship between offspring size and performance is ubiquitous, the cause of this relationship remains elusive. By linking metabolic and life-history theory, we provide a general explanation for why larger offspring perform better than smaller offspring. Using high-throughput respirometry arrays, we link metabolic rate to offspring size in two species of marine bryozoan. We found that metabolism scales allometrically with offspring size in both species: while larger offspring use absolutely more energy than smaller offspring, larger offspring use proportionally less of their maternally derived energy throughout the dependent, non-feeding phase. The increased metabolic efficiency of larger offspring while dependent on maternal investment may explain offspring size effects—larger offspring reach nutritional independence (feed for themselves) with a higher proportion of energy relative to structure than smaller offspring. These findings offer a potentially universal explanation for why larger offspring tend to perform better than smaller offspring but studies on other taxa are needed.

scholarly journals Offspring size effects vary over fine spatio-temporal scales in Atlantic salmon (Salmo salar)

2013 ◽  
Vol 70 (1) ◽  
pp. 5-12 ◽  
Author(s):  
Grethe Robertsen ◽  
Helge Skoglund ◽  
Sigurd Einum
Keyword(s):  
Genetic Variation ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Egg Size ◽  
Offspring Size ◽  
Stabilizing Selection ◽  
Atlantic Salmon Salmo Salar ◽  
Natural Stream ◽  
Spatio Temporal ◽  
The Relationship

Classic offspring-size theory predicts that a single level of investment per offspring maximizes parental reproductive success in a given environment. Yet, substantial variation in offspring size is often observed among females within populations. Variation at this scale may occur because spatio-temporal variation in stabilizing selection prevents erosion of genetic variation. We tested whether patterns of size-specific offspring survival of Atlantic salmon (Salmo salar) varies across location and season within a short stretch of a natural stream by manipulating the emergence timing of juveniles from 12 families with different mean egg sizes and assessing their performance at two locations. The relationship between egg size and juvenile survival varied temporally and spatially; large eggs were advantageous for early emergers in one location, whereas egg size had no effect in the other. Furthermore, the performance of later emerging juveniles did not depend on egg size in either location, possibly because the early emergers had grown or established territories. Thus, selection on offspring size can be complex and vary across short periods of time and small geographic distances, thereby preventing the erosion of genetic variation expected under consistent stabilizing selection.

scholarly journals The Relationship between Offspring Size and Performance in the Sea

2008 ◽  
Vol 171 (2) ◽  
pp. 214-224 ◽  
Author(s):  
Dustin J. Marshall ◽  
Michael J. Keough
Keyword(s):  
Offspring Size ◽  
And Performance ◽  
The Relationship

Reproductive ecology of the slow worm (Anguis fragilis) in the northwest Iberian Peninsula

2004 ◽  
Vol 54 (4) ◽  
pp. 353-371 ◽  
Author(s):  
Pedro Galán ◽  
Ricardo Ferreiro
Keyword(s):  
Reproductive Output ◽  
Natural Populations ◽  
Tail Length ◽  
Activity Cycle ◽  
Offspring Size ◽  
Reproductive Characteristics ◽  
Pregnant Females ◽  
Anguis Fragilis ◽  
The Relationship ◽  
Northwest Iberian Peninsula

AbstractThe reproductive characteristics of the slow worm (Anguis fragilis) were studied in A Coruña (Galicia, NW Spain) in 1999, 2000, 2001 and 2002. Data were mainly obtained through pregnant females captured in natural populations which subsequently gave birth under controlled conditions in the laboratory and the resulting neonates were examined. Marked individuals in a field population were also monitored. This field study allowed us to gain knowledge of the activity and reproductive cycle of the monitored population. A total of 68 births and 468 neonates were obtained, allowing us to determine the basic reproductive characteristics of the populations studied such as the litter size, offspring weight, offspring size and minimum maturity size for females: 135-150 mm snout vent length (SVL). The relationship between several variables related to offspring and their mothers showed a positive relation between size and mass of the litter and offspring with maternal size. A relationship between maternal tail length and litter mass was not observed. Unlike other studied populations of this species, most of the females of the A Coruña population (88.8%) reproduce annually. We found a probable relationship between female annual reproductive output and latitude, likely related to differences in environmental temperature. The activity cycle for the monitored population (from February to mid-December) is the longest known for the species.

scholarly journals The shark-tuna dichotomy: why tuna lay tiny eggs but sharks produce large offspring

2018 ◽  
Vol 5 (8) ◽  
pp. 180453 ◽  
Author(s):  
Richard M. Sibly ◽  
Astrid Kodric-Brown ◽  
Susan M. Luna ◽  
James H. Brown
Keyword(s):  
Offspring Size ◽  
Death Rates ◽  
Adult Body Mass ◽  
Straight Line ◽  
Adult Body ◽  
Intermediate Size ◽  
Log Linear ◽  
Type 3 ◽  
The Relationship

Teleosts such as tunas and billfish lay millions of tiny eggs weighing on the order of 0.001 g, whereas chondrichthyes such as sharks and rays produce a few eggs or live offspring weighing about 2% of adult body mass, as much as 10 000 g in some species. Why are the strategies so extreme, and why are intermediate ones absent? Building on previous work, we show quantitatively how offspring size reflects the relationship between growth and death rates. We construct fitness contours as functions of offspring size and number, and show how these can be derived from juvenile growth and survivorship curves. Convex contours, corresponding to Pearl Type 1 and 2 survivorship curves, select for extremes, either miniscule or large offspring; concave contours select for offspring of intermediate size. Of particular interest are what we call critical straight-line fitness contours, corresponding to log-linear Pearl Type 3 survivorship curves, which separate regimes that select for opposite optimal offspring sizes.

Interstellar gas in the central region of the Galaxy

1967 ◽  
Vol 31 ◽  
pp. 239-251 ◽  
Author(s):  
F. J. Kerr
Keyword(s):  
Central Region ◽  
Galactic Plane ◽  
Neutral Hydrogen ◽  
Continuum Emission ◽  
Galactic Centre ◽  
Interstellar Gas ◽  
Hydrogen Recombination ◽  
The Galaxy ◽  
Centre Region ◽  
The Relationship

A review is given of information on the galactic-centre region obtained from recent observations of the 21-cm line from neutral hydrogen, the 18-cm group of OH lines, a hydrogen recombination line at 6 cm wavelength, and the continuum emission from ionized hydrogen.Both inward and outward motions are important in this region, in addition to rotation. Several types of observation indicate the presence of material in features inclined to the galactic plane. The relationship between the H and OH concentrations is not yet clear, but a rough picture of the central region can be proposed.

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