An ecological explanation for hyperallometric scaling of reproduction

2021 ◽  
Author(s):  
Tomos Potter ◽  
Anja Felmy
Keyword(s):  
Body Size ◽  
Reproductive Output ◽  
Resource Competition ◽  
Natural Populations ◽  
Scaling Exponent ◽  
Wild Populations ◽  
Wet Season ◽  
Size Dependent ◽  
In The Wild ◽  
The Relationship

AbstractIn wild populations, large individuals have disproportionately higher reproductive output than smaller individuals. We suggest an ecological explanation for this observation: asymmetry within populations in rates of resource assimilation, where greater assimilation causes both increased reproduction and body size. We assessed how the relationship between size and reproduction differs between wild and lab-reared Trinidadian guppies. We show that (i) reproduction increased disproportionately with body size in the wild but not in the lab, where effects of resource competition were eliminated; (ii) in the wild, the scaling exponent was greatest during the wet season, when resource competition is strongest; and (iii) detection of hyperallometric scaling of reproduction is inevitable if individual differences in assimilation are ignored. We propose that variation among individuals in assimilation – caused by size-dependent resource competition, niche expansion, and chance – can explain patterns of hyperallometric scaling of reproduction in natural populations.

scholarly journals Captive-bred Atlantic salmon released into the wild have fewer offspring than wild-bred fish and decrease population productivity

2020 ◽  
Vol 287 (1937) ◽  
pp. 20201671
Author(s):  
Ronan James O'Sullivan ◽  
Tutku Aykanat ◽  
Susan E. Johnston ◽  
Ger Rogan ◽  
Russell Poole ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Natural Populations ◽  
Mixed Population ◽  
Lifetime Reproductive Success ◽  
Wild Relative ◽  
Offspring Survival ◽  
Wild Populations ◽  
Annual Productivity ◽  
In The Wild ◽  
Analyse Data

The release of captive-bred animals into the wild is commonly practised to restore or supplement wild populations but comes with a suite of ecological and genetic consequences. Vast numbers of hatchery-reared fish are released annually, ostensibly to restore/enhance wild populations or provide greater angling returns. While previous studies have shown that captive-bred fish perform poorly in the wild relative to wild-bred conspecifics, few have measured individual lifetime reproductive success (LRS) and how this affects population productivity. Here, we analyse data on Atlantic salmon from an intensely studied catchment into which varying numbers of captive-bred fish have escaped/been released and potentially bred over several decades. Using a molecular pedigree, we demonstrate that, on average, the LRS of captive-bred individuals was only 36% that of wild-bred individuals. A significant LRS difference remained after excluding individuals that left no surviving offspring, some of which might have simply failed to spawn, consistent with transgenerational effects on offspring survival. The annual productivity of the mixed population (wild-bred plus captive-bred) was lower in years where captive-bred fish comprised a greater fraction of potential spawners. These results bolster previous empirical and theoretical findings that intentional stocking, or non-intentional escapees, threaten, rather than enhance, recipient natural populations.

Testing models of biological scaling with mammalian population densities

2003 ◽  
Vol 81 (5) ◽  
pp. 844-851 ◽  
Author(s):  
F Stephen Dobson ◽  
Bertram Zinner ◽  
Marina Silva
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Mammalian Species ◽  
Fractal Dimensions ◽  
Scaling Exponent ◽  
Population Densities ◽  
Biological Variables ◽  
Terrestrial Habitats ◽  
Broad Variety ◽  
The Relationship

Two hypotheses have been suggested to explain the form of interspecific scaling of organismal characteristics to body size, such as the well-known increase in total metabolism with body mass. A hypothesis based on simple Euclidean geometry suggests that the scaling of many biological variables to body size should have a scaling exponent of 2/3, or [Formula: see text]0.667. On the other hand, according to a hypothesis based on fractal dimensions, the relationship between biological variables and body mass should have a scaling exponent of 0.750. We conducted a power analysis of the predicted exponents of scaling under the Euclidean and fractal hypotheses, using average adult body masses and population densities collected from the published literature on mammalian species. The collected data reflect 987 mammal populations from a broad variety of terrestrial habitats. Using statistical methods we determined the sample sizes required to decide between the values of the scaling exponent of the density-to-mass relationship based on the Euclidean (–0.667) and fractal (–0.750) hypotheses. Non-linearities in the dataset and insufficient power plagued our tests of the predictions. We found that mammalian species weighing less than 100 kg had a linear scaling pattern, sufficient power to reveal a difference between the scaling coefficients –0.667 and –0.750, and an actual scaling coefficient of –0.719 (barely significantly different from –0.667 but not from –0.750). Thus, our results support the fractal hypothesis, though the support was not particularly strong, which suggests that the relationship between body mass and population density should have a scaling exponent of –0.750.

scholarly journals On being the right size: increased body size is associated with reduced telomere length under natural conditions

2015 ◽  
Vol 282 (1820) ◽  
pp. 20152331 ◽  
Author(s):  
Thor Harald Ringsby ◽  
Henrik Jensen ◽  
Henrik Pärn ◽  
Thomas Kvalnes ◽  
Winnie Boner ◽  
...  
Keyword(s):  
Body Size ◽  
Telomere Length ◽  
Natural Populations ◽  
Negative Relationship ◽  
House Sparrows ◽  
Selection Regime ◽  
Trade Offs ◽  
Length Changes ◽  
The Relationship ◽  
Telomere Dynamics

Evolution of body size is likely to involve trade-offs between body size, growth rate and longevity. Within species, larger body size is associated with faster growth and ageing, and reduced longevity, but the cellular processes driving these relationships are poorly understood. One mechanism that might play a key role in determining optimal body size is the relationship between body size and telomere dynamics. However, we know little about how telomere length is affected when selection for larger size is imposed in natural populations. We report here on the relationship between structural body size and telomere length in wild house sparrows at the beginning and end of a selection regime for larger parent size that was imposed for 4 years in an isolated population of house sparrows. A negative relationship between fledgling size and telomere length was present at the start of the selection; this was extended when fledgling size increased under the selection regime, demonstrating a persistent covariance between structural size and telomere length. Changes in telomere dynamics, either as a correlated trait or a consequence of larger size, could reduce potential longevity and the consequent trade-offs could thereby play an important role in the evolution of optimal body size.

scholarly journals Which frog's legs do froggies eat? The use of DNA barcoding for identification of deep frozen frog legs (Dicroglossidae, Amphibia) commercialized in France

2017 ◽  
Author(s):  
Annemarie Ohler ◽  
Violaine Nicolas
Keyword(s):  
Dna Barcoding ◽  
Large Scale ◽  
Natural Populations ◽  
Morphological Diversity ◽  
Iucn Red List ◽  
Red List ◽  
Wild Populations ◽  
16S Gene ◽  
The Status ◽  
In The Wild

Several millions frogs captured in the wild in Indonesia are sold for food yearly in French supermarkets, as deep frozen frog legs. They are commercialized as Rana macrodon, but up to 15 look-alike species might also be concerned by this trade. From December 2012 to May 2013, we bought 209 specimens of deep frozen frog legs, and identified them through a barcoding approach based on the 16S gene. Our results show that 206 out of the 209 specimens belong to Fejervarya cancrivora, two to Limnonectes macrodon and one to F. moodiei. Thus only 0.96 % of the frogs were correctly identified. Unless misclassification was intentional, it seems that Indonesian frog leg exporters are not able to discriminate between the species. The quasi absence of L. macrodon in our samples might be an indication of its rarity, confirming that its natural populations are declining rapidly, in agreement with its “vulnerable” status according to the IUCN Red List. Our results show that the genetic and morphological diversity of the frogs in trade is much higher than the genetic and morphological diversity measured so far by scientific studies. These results underline the need for large scale studies to assess the status of wild populations.

Variations in the Correlation of Body Size with Concentrations of Cu and Ag in the Bivalve Macoma balthica

1981 ◽  
Vol 38 (9) ◽  
pp. 1059-1064 ◽  
Author(s):  
Carol R. Strong ◽  
Samuel N. Luoma
Keyword(s):  
Growth Rate ◽  
Body Size ◽  
San Francisco ◽  
Metal Contamination ◽  
Macoma Balthica ◽  
Indicator Organisms ◽  
Size Dependent ◽  
Chemical Pollutants ◽  
Uptake Rates ◽  
The Relationship

The relationship between body size and concentrations of Cu and Ag varied from strongly positive to strongly negative in four populations of the bivalve Macoma balthica in San Francisco Bay. The correlations appeared to be influenced by the degree of enrichment in tissues, size-dependent differences and seasonal variations in growth rate, and size-dependent differences in uptake rates. The use of benthic indicator organisms to assess metal contamination requires understanding the relationship between metal concentration and body size at least within each population, and in some cases within each sample from each population.Key words: indicator species, Mollusca, Macoma balthica, body size, metals, chemical pollutants

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.

Weather matters: begging calls are temperature- and size-dependent signals of offspring state

Behaviour ◽  
2016 ◽  
Vol 153 (8) ◽  
pp. 871-896 ◽  
Author(s):  
Roslyn Dakin ◽  
Jenny Q. Ouyang ◽  
Ádám Z. Lendvai ◽  
Mark F. Haussmann ◽  
Ignacio T. Moore ◽  
...  
Keyword(s):  
Body Size ◽  
Ambient Temperature ◽  
Body Mass ◽  
Environmental Conditions ◽  
Tachycineta Bicolor ◽  
Dependent Manner ◽  
Tree Swallows ◽  
Size Dependent ◽  
Call Production ◽  
The Relationship

Begging calls provide a way for parents to gauge offspring state. Although temperature is known to affect call production, previous studies have not examined the influence of ambient temperature at the nest. We recorded ambient temperature and begging calls of 3 day-old tree swallows (Tachycineta bicolor). Our results indicate that typical daily temperature flux can dramatically alter a brood’s begging calls, depending on body size. Broods with small (low body mass) nestlings decreased the rate and length of their calls at colder temperatures, consistent with a biophysical constraint. In contrast, broods with large (high body mass) nestlings increased the rate of their calls at colder temperatures. Parents responded in a context-dependent manner, returning more rapidly after smaller nestlings gave longer begging calls. Our results suggest that the function of offspring begging calls is highly dynamic, with environmental conditions altering the relationship between begging calls and offspring state.

scholarly journals Effects of extreme weather on two sympatric Australian passerine bird species

2017 ◽  
Vol 372 (1723) ◽  
pp. 20160148 ◽  
Author(s):  
Janet L. Gardner ◽  
Eleanor Rowley ◽  
Perry de Rebeira ◽  
Alma de Rebeira ◽  
Lyanne Brouwer
Keyword(s):  
Body Size ◽  
Natural Populations ◽  
Bird Species ◽  
Passerine Bird ◽  
Climatic Conditions ◽  
Individual Level ◽  
Size Dependent ◽  
Extreme Climatic Events ◽  
Coexisting Species ◽  
Dependent Mortality

Despite abundant evidence that natural populations are responding to climate change, there are few demonstrations of how extreme climatic events (ECEs) affect fitness. Climate warming increases adverse effects of exposure to high temperatures, but also reduces exposure to cold ECEs. Here, we investigate variation in survival associated with severity of summer and winter conditions, and whether survival is better predicted by ECEs than mean temperatures using data from two coexisting bird species monitored over 37 years in southwestern Australia, red-winged fairy-wrens, Malurus elegans and white-browed scrubwrens, Sericornis frontalis . Changes in survival were associated with temperature extremes more strongly than average temperatures. In scrubwrens, winter ECEs were associated with survival within the same season. In both species, survival was associated with body size, and there was evidence that size-dependent mortality was mediated by carry-over effects of climate in the previous season. For fairy-wrens, mean body size declined over time but this could not be explained by size-dependent mortality as the effects of body size on survival were consistently positive. Our study demonstrates how ECEs can have individual-level effects on survival that are not reflected in long-term morphological change, and the same climatic conditions can affect similar-sized, coexisting species in different ways. This article is part of the themed issue ‘Behavioural, ecological and evolutionary responses to extreme climatic events’.

scholarly journals Independent evolution towards larger body size in the distinctive Faroe Island mice

2021 ◽  
Author(s):  
Ricardo Wilches ◽  
William H Beluch ◽  
Ellen McConnell ◽  
Diethard Tautz ◽  
Yingguang Frank Chan
Keyword(s):  
Body Size ◽  
Meta Analysis ◽  
Small Body ◽  
Laboratory Mouse ◽  
Large Body ◽  
Natural Populations ◽  
Size Variation ◽  
Phenotypic Traits ◽  
Island Population ◽  
Multiple Loci

Abstract Most phenotypic traits in nature involve the collective action of many genes. Traits that evolve repeatedly are particularly useful for understanding how selection may act on changing trait values. In mice, large body size has evolved repeatedly on islands and under artificial selection in the laboratory. Identifying the loci and genes involved in this process may shed light on the evolution of complex, polygenic traits. Here, we have mapped the genetic basis of body size variation by making a genetic cross between mice from the Faroe Islands, which are among the largest and most distinctive natural populations of mice in the world, and a laboratory mouse strain selected for small body size, SM/J. Using this F2 intercross of 841 animals, we have identified 111 loci controlling various aspects of body size, weight and growth hormone levels. By comparing against other studies, including the use of a joint meta-analysis, we found that the loci involved in the evolution of large size in the Faroese mice were largely independent from those of a different island population or other laboratory strains. We hypothesize that colonization bottleneck, historical hybridization, or the redundancy between multiple loci have resulted in the Faroese mice achieving an outwardly similar phenotype through a distinct evolutionary path.

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