scholarly journals Decomposing the effects of ocean environments on predator–prey body-size relationships in food webs

2018 ◽  
Vol 5 (7) ◽  
pp. 180707 ◽  
Author(s):  
Tomoya Dobashi ◽  
Midori Iida ◽  
Kazuhiro Takemoto

Body-size relationships between predators and their prey are important in ecological studies because they reflect the structure and function of food webs. Inspired by studies on the impact of global warming on food webs, the effects of temperature on body-size relationships have been widely investigated; however, the impact of environmental factors on body-size relationships has not been fully evaluated because climate warming affects various ocean environments. Thus, here, we comprehensively investigated the effects of ocean environments and predator–prey body-size relationships by integrating a large-scale dataset of predator–prey body-size relationships in marine food webs with global oceanographic data. We showed that various oceanographic parameters influence prey size selection. In particular, oxygen concentration, primary production and salinity, in addition to temperature, significantly alter body-size relationships. Furthermore, we demonstrated that variability (seasonality) of ocean environments significantly affects body-size relationships. The effects of ocean environments on body-size relationships were generally remarkable for small body sizes, but were also significant for large body sizes and were relatively weak for intermediate body sizes, in the cases of temperature seasonality, oxygen concentration and salinity variability. These findings break down the complex effects of ocean environments on body-size relationships, advancing our understanding of how ocean environments influence the structure and functioning of food webs.

1989 ◽  
Vol 48 (1) ◽  
pp. 15-20 ◽  
Author(s):  
Reynaldo Martorell

This is a brief discussion of the "small but healthy" hypothesis proposed by David Seckler in the early 1980s. Four basic points are made. First, adults in developing countries have small body sizes largely as a result of poor diets and infection during childhood. Therefore, to acclaim small body sizes as a desirable attribute for populations is also to affirm that its causes are desirable. Second, monitoring the growth of children is widely recognized as an excellent tool for detecting health problems. Growth retardation, rather than an innocuous response to environmental stimuli, is a warning signal of increased risk of morbidity and mortality. Third, the conditions which give rise to stunted children also affect other aspects such as cognitive development. Finally, stunted girls who survive to be short women are at greater risk of delivering growth retarded infants with a greater probability of dying in infancy. For all these reasons, small is not healthy.


2021 ◽  
Author(s):  
Charlene L. McCord ◽  
W. James Cooper ◽  
Chloe M. Nash ◽  
Mark W. Westneat

AbstractThe damselfishes (family Pomacentridae) inhabit near-shore communities in tropical and temperature oceans as one of the major lineages with ecological and economic importance for coral reef fish assemblages. Our understanding of their evolutionary ecology, morphology and function has often been advanced by increasingly detailed and accurate molecular phylogenies. Here we present the next stage of multi-locus, molecular phylogenetics for the group based on analysis of 12 nuclear and mitochondrial gene sequences from 330 of the 422 damselfish species. The resulting well-resolved phylogeny helps to address several important questions about higher-level damselfish relationships and the monophyly of genera, including Chromis, Chrysiptera, Parma and Stegastes. A time-calibrated phylogenetic tree scaled using fossil data and recent estimated ovalentarian clade ages, yields an older root age for the family (55.3 mya) than previously proposed, refines the age of origin for a number of diverse genera, and shows that ecological changes during the Eocene-Oligocene transition provided opportunities for damselfish diversification. We explored the idea that body size extremes have evolved repeatedly among the Pomacentridae, and demonstrate that large and small body sizes have evolved independently at least 30 times and with asymmetric rates of transition. We tested the hypothesis that transitions among three dietary ecotypes (benthic herbivory, pelagic planktivory and intermediate omnivory) are asymmetric, with higher transition rates from intermediate omnivory to either planktivory or herbivory. Using multistate hidden-state speciation and extinction models, we found that dietary ecotype is significantly associated with patterns of diversification across the damselfishes, and that the highest rates of net diversification are associated with pelagic planktivory. We also conclude that the pattern of evolutionary diversification in feeding ecology, with frequent and asymmetrical transitions between a small number of feeding ecotypes, is largely restricted to the subfamily Pomacentrinae in the Indo-West Pacific.


2016 ◽  
Vol 283 (1833) ◽  
pp. 20160816 ◽  
Author(s):  
Rowan Trebilco ◽  
Nicholas K. Dulvy ◽  
Sean C. Anderson ◽  
Anne K. Salomon

Theory predicts that bottom-heavy biomass pyramids or ‘stacks’ should predominate in real-world communities if trophic-level increases with body size (mean predator-to-prey mass ratio (PPMR) more than 1). However, recent research suggests that inverted biomass pyramids (IBPs) characterize relatively pristine reef fish communities. Here, we estimated the slope of a kelp forest fish community biomass spectrum from underwater visual surveys. The observed biomass spectrum slope is strongly positive, reflecting an IBP. This is incongruous with theory because this steep positive slope would only be expected if trophic position decreased with increasing body size (consumer-to-resource mass ratio, less than 1). We then used δ 15 N signatures of fish muscle tissue to quantify the relationship between trophic position and body size and instead detected strong evidence for the opposite, with PPMR ≈ 1650 (50% credible interval 280–12 000). The natural history of kelp forest reef fishes suggests that this paradox could arise from energetic subsidies in the form of movement of mobile consumers across habitats, and from seasonally pulsed production inputs at small body sizes. There were four to five times more biomass at large body sizes (1–2 kg) than would be expected in a closed steady-state community providing a measure of the magnitude of subsidies.


Genetics ◽  
1989 ◽  
Vol 122 (1) ◽  
pp. 193-203 ◽  
Author(s):  
D E Cowley ◽  
D Pomp ◽  
W R Atchley ◽  
E J Eisen ◽  
D Hawkins-Brown

Abstract Embryo transfers were used to demonstrate that the genotype of the mother providing the uterine developmental environment significantly influences postnatal growth and adult body size of her progeny. Irrespective of their own genotype, mouse embryos transferred into the uterus of an inbred strain with large body size (C3H) had greater body weights, longer tails and higher growth rates than those transferred into the uterus of a strain with small body size (SWR). Uterine heterosis on body size was smaller than progeny heterosis, and both progeny and uterine heterosis persisted in adult mice. Uterine litter size was significantly negatively associated with body weight, tail length, growth rate and the timing of developmental events. The inbred SWR strain was more sensitive to the embryo transfer procedure than the C3H strain, but effects due to embryo transfer were moderate. Prenatal uterine effects have ramifications for biotechnologies utilizing embryo transfer as well as predictions about evolutionary change by selection.


2018 ◽  
Author(s):  
Clémentine Renneville ◽  
Alexis Millot ◽  
Simon Agostini ◽  
David Carmignac ◽  
Gersende Maugars ◽  
...  

ABSTRACTAnthropogenic perturbations such as harvesting often select against a large body size and are predicted to induce rapid evolution towards smaller body sizes and earlier maturation. However, body-size evolvability and, hence, adaptability to anthropogenic perturbations remain seldom evaluated in wild populations. Here, we use a laboratory experiment over 6 generations to measure the ability of wild-caught medaka fish (Oryzias latipes) to evolve in response to bidirectional size-dependent selection mimicking opposite harvest regimes. Specifically, we imposed selection against a small body size (Large line), against a large body size (Small line) or random selection (Control line), and measured correlated responses across multiple phenotypic, life-history and endocrine traits. As expected, the Large line evolved faster somatic growth and delayed maturation, but also evolved smaller body sizes at hatch, with no change in average levels of pituitary gene expressions of luteinizing, folliclestimulating or growth (GH) hormones. In contrast, the Small medaka line was unable to evolve smaller body sizes or earlier maturation, but evolved smaller body sizes at hatch and showed marginally-significant signs of increased reproductive investment, including larger egg sizes and elevated pituitary GH production. Natural selection on medaka body size was too weak to significantly hinder the effect of artificial selection, indicating that the asymmetric body-size response to size-dependent selection reflected an asymmetry in body-size evolvability. Our results show that trait evolvability may be contingent upon the direction of selection, and that a detailed knowledge of trait evolutionary potential is needed to forecast population response to anthropogenic change.


Author(s):  
Ricardo Wilches ◽  
William H Beluch ◽  
Ellen McConnell ◽  
Diethard Tautz ◽  
Yingguang Frank Chan

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.


2021 ◽  
Vol 25 (9) ◽  
pp. 44-49
Author(s):  
S.S. Uskova

The evaluation issues on the aggregate’s extraction on the ecosystem of bodies of water has been considered. The dredgers' impact of various capacities on bodies of water of different capacities have been compared, as well as on food supply change of bodies of water for benthos eater. The research findings have showed the dragger's impact of a higher capacity is bigger on a large body of water than this of a lower capacity on a small body of water. The impact manifests itself in decreasing the number and biomass of macrozoobenthos in the area used for the oil and lubricants extraction and the downstream flow. It has been found that the complete destruction of macrozoobenthos at the site of hydraulic engineering activities has not been detected either in small rivers or in large reservoirs.


2015 ◽  
Vol 113 (4) ◽  
pp. 862-867 ◽  
Author(s):  
Blaire Van Valkenburgh ◽  
Matthew W. Hayward ◽  
William J. Ripple ◽  
Carlo Meloro ◽  
V. Louise Roth

Large mammalian terrestrial herbivores, such as elephants, have dramatic effects on the ecosystems they inhabit and at high population densities their environmental impacts can be devastating. Pleistocene terrestrial ecosystems included a much greater diversity of megaherbivores (e.g., mammoths, mastodons, giant ground sloths) and thus a greater potential for widespread habitat degradation if population sizes were not limited. Nevertheless, based on modern observations, it is generally believed that populations of megaherbivores (>800 kg) are largely immune to the effects of predation and this perception has been extended into the Pleistocene. However, as shown here, the species richness of big carnivores was greater in the Pleistocene and many of them were significantly larger than their modern counterparts. Fossil evidence suggests that interspecific competition among carnivores was relatively intense and reveals that some individuals specialized in consuming megaherbivores. To estimate the potential impact of Pleistocene large carnivores, we use both historic and modern data on predator–prey body mass relationships to predict size ranges of their typical and maximum prey when hunting as individuals and in groups. These prey size ranges are then compared with estimates of juvenile and subadult proboscidean body sizes derived from extant elephant growth data. Young proboscideans at their most vulnerable age fall within the predicted prey size ranges of many of the Pleistocene carnivores. Predation on juveniles can have a greater impact on megaherbivores because of their long interbirth intervals, and consequently, we argue that Pleistocene carnivores had the capacity to, and likely did, limit megaherbivore population sizes.


Author(s):  
Isain Zapata ◽  
M. Leanne Lilly ◽  
Meghan E. Herron ◽  
James A. Serpell ◽  
Carlos E. Alvarez

AbstractVery little is known about the etiology of personality and psychiatric disorders. Because the core neurobiology of many such traits is evolutionarily conserved, dogs present a powerful model. We previously reported genome scans of breed averages of ten traits related to fear, anxiety, aggression and social behavior in multiple cohorts of pedigree dogs. As a second phase of that discovery, here we tested the ability of markers at 13 of those loci to predict canine behavior in a community sample of 397 pedigree and mixed-breed dogs with individual-level genotype and phenotype data. We found support for all markers and loci. By including 122 dogs with veterinary behavioral diagnoses in our cohort, we were able to identify eight loci associated with those diagnoses. Logistic regression models showed subsets of those loci could predict behavioral diagnoses. We corroborated our previous findings that small body size is associated with many problem behaviors and large body size is associated with increased trainability. Children in the home were associated with anxiety traits; illness and other animals in the home with coprophagia; working-dog status with increased energy and separation-related problems; and competitive dogs with increased aggression directed at familiar dogs, but reduced fear directed at humans and unfamiliar dogs. Compared to other dogs, Pit Bull-type dogs were not defined by a set of our markers and were not more aggressive; but they were strongly associated with pulling on the leash. Using severity-threshold models, Pit Bull-type dogs showed reduced risk of owner-directed aggression (75th quantile) and increased risk of dog-directed fear (95th quantile). Our findings have broad utility, including for clinical and breeding purposes, but we caution that thorough understanding is necessary for their interpretation and use.


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