Head-to-body size allometry in wasps (Vespidae): does brain housing constrain the evolution of small body sizes?

2019 ◽  
Vol 66 (4) ◽  
pp. 647-651
Author(s):  
S. O’Donnell
Keyword(s):  
Body Size ◽  
Small Body ◽  
Body Sizes

Reproductive performance in a phyletic dwarf, the spider crab Petramithrax pygmaeus (Bell, 1836) (Decapoda: Brachyura: Mithracidae)

2020 ◽  
Vol 40 (3) ◽  
pp. 325-329
Author(s):  
Joshua T Fields ◽  
Hayden K Mullen ◽  
Clayr M Kroenke ◽  
Kyla A Salomon ◽  
Abby J Craft ◽  
...  
Keyword(s):  
Body Size ◽  
Reproductive Performance ◽  
Related Species ◽  
Egg Production ◽  
Marine Invertebrates ◽  
Small Body ◽  
Reproductive Investment ◽  
Spider Crab ◽  
Closely Related Species ◽  
Body Sizes

Abstract The spider crab Petramithrax pygmaeus (Bell, 1836), a phyletic dwarf, was used to test predictions regarding reproductive performance in small marine invertebrates. Considering the disproportional increase in brooding costs and the allometry of egg production with increasing body size, it was expected that this minute-size species would produce large broods compared to closely related species that attain much larger body sizes. Fecundity in P. pygmaeus females carrying early and late eggs varied, respectively, between 17 and 172 eggs crab–1 (mean ± SD = 87.97 ± 48.39) and between 13 and 159 eggs crab–1 (55.04 ± 40.29). Females did not experience brood loss during egg development. Egg volume in females carrying early and late eggs varied, respectively, between 0.13 and 0.40 mm3 (0.22 ± 0.07) and between 0.15 and 0.42 mm3 (0.26 ± 0.06 mm3). Reproductive output (RO) varied between 0.91 and 8.73% (3.81 ± 2.17%) of female dry body weight. The RO of P. pygmaeus was lower than that reported for closely related species with larger body sizes. The slope (b = 0.95 ± 0.15) of the line describing the relationship between brood and parental female dry weight was not statistically significant from unity. Overall, our results disagree with the notion that the allometry of gamete production and increased physiological costs with increased brood size explain the association between brooding and small body size in marine invertebrates. Comparative studies on the reproductive investment of brooding species belonging to monophyletic clades with extensive differences in body size are warranted to further our understanding about disparity in egg production in brooding marine invertebrates.

scholarly journals Functional diversity of small-mammal postcrania is linked to both substrate preference and body size

2020 ◽  
Vol 66 (5) ◽  
pp. 539-553
Author(s):  
Lucas N Weaver ◽  
David M Grossnickle
Keyword(s):  
Body Size ◽  
Phenotypic Diversity ◽  
Small Body ◽  
Ecological Factors ◽  
Morphological Divergence ◽  
Functional Diversification ◽  
Evolutionary Patterns ◽  
Selective Pressures ◽  
Trade Offs ◽  
Body Sizes

Abstract Selective pressures favor morphologies that are adapted to distinct ecologies, resulting in trait partitioning among ecomorphotypes. However, the effects of these selective pressures vary across taxa, especially because morphology is also influenced by factors such as phylogeny, body size, and functional trade-offs. In this study, we examine how these factors impact functional diversification in mammals. It has been proposed that trait partitioning among mammalian ecomorphotypes is less pronounced at small body sizes due to biomechanical, energetic, and environmental factors that favor a “generalist” body plan, whereas larger taxa exhibit more substantial functional adaptations. We title this the Divergence Hypothesis (DH) because it predicts greater morphological divergence among ecomorphotypes at larger body sizes. We test DH by using phylogenetic comparative methods to examine the postcranial skeletons of 129 species of taxonomically diverse, small-to-medium-sized (<15 kg) mammals, which we categorize as either “tree-dwellers” or “ground-dwellers.” In some analyses, the morphologies of ground-dwellers and tree-dwellers suggest greater between-group differentiation at larger sizes, providing some evidence for DH. However, this trend is neither particularly strong nor supported by all analyses. Instead, a more pronounced pattern emerges that is distinct from the predictions of DH: within-group phenotypic disparity increases with body size in both ground-dwellers and tree-dwellers, driven by morphological outliers among “medium”-sized mammals. Thus, evolutionary increases in body size are more closely linked to increases in within-locomotor-group disparity than to increases in between-group disparity. We discuss biomechanical and ecological factors that may drive these evolutionary patterns, and we emphasize the significant evolutionary influences of ecology and body size on phenotypic diversity.

Body Size, Adaptation and Function

1989 ◽  
Vol 48 (1) ◽  
pp. 15-20 ◽  
Author(s):  
Reynaldo Martorell
Keyword(s):  
Developing Countries ◽  
Body Size ◽  
Cognitive Development ◽  
Growth Retardation ◽  
Small Body ◽  
Warning Signal ◽  
Increased Risk ◽  
Body Sizes ◽  
And Function ◽  
Excellent Tool

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.

scholarly journals How do seemingly non-vagile clades accomplish trans-marine dispersal? Trait and dispersal evolution in the landfowl (Aves: Galliformes)

2017 ◽  
Vol 284 (1854) ◽  
pp. 20170210 ◽  
Author(s):  
Peter A. Hosner ◽  
Joseph A. Tobias ◽  
Edward L. Braun ◽  
Rebecca T. Kimball
Keyword(s):  
Body Size ◽  
Small Body ◽  
New Guinea ◽  
Oceanic Islands ◽  
Wing Shape ◽  
Dispersal Ability ◽  
Marine Dispersal ◽  
Key Factor ◽  
Body Sizes ◽  
Dispersal Evolution

Dispersal ability is a key factor in determining insular distributions and island community composition, yet non-vagile terrestrial organisms widely occur on oceanic islands. The landfowl (pheasants, partridges, grouse, turkeys, quails and relatives) are generally poor dispersers, but the Old World quail ( Coturnix ) are a notable exception. These birds evolved small body sizes and high-aspect-ratio wing shapes, and hence are capable of trans-continental migrations and trans-oceanic colonization. Two monotypic partridge genera, Margaroperdix of Madagascar and Anurophasis of alpine New Guinea, may represent additional examples of trans-marine dispersal in landfowl, but their body size and wing shape are typical of poorly dispersive continental species. Here, we estimate historical relationships of quail and their relatives using phylogenomics, and infer body size and wing shape evolution in relation to trans-marine dispersal events. Our results show that Margaroperdix and Anurophasis are nested within the Coturnix quail, and are each ‘island giants’ that independently evolved from dispersive, Coturnix -like ancestral populations that colonized and were subsequently isolated on Madagascar and New Guinea. This evolutionary cycle of gain and loss of dispersal ability, coupled with extinction of dispersive taxa, can result in the false appearance that non-vagile taxa somehow underwent rare oceanic dispersal.

Hierarchy and the reconstruction of evolutionary trends: evidence for constraints on the evolution of body size in terrestrial caniform carnivorans (Mammalia)

Paleobiology ◽  
2008 ◽  
Vol 34 (4) ◽  
pp. 553-562 ◽  
Author(s):  
John A. Finarelli
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Small Body ◽  
Information Criterion ◽  
Size Increase ◽  
Size Evolution ◽  
Species Pairs ◽  
Body Sizes ◽  
Intermediate Size ◽  
Body Size Evolution

Body mass is an important organism-level variable in mammalian biology, correlated with physiology, life history, and ecology. To analyze the dynamics of body size evolution, increases and decreases in body mass were tallied for ancestor-descendant (AD) species pairs for 519 terrestrial caniform taxa. To account for uncertainty phylogeny, a bootstrapping routine shuffled hypothesized AD pairs, and average proportions of increases were binned as a function of ancestral body mass. A set of models relating the rate of body size increase were evaluated with the Akaike Information Criterion (AIC). AIC selected three models of the candidate set as equivalent in support by the observed body mass data. These three models propose body size increase for small AD pairs and body size decrease for large AD pairs, although they differ in their treatment of taxa at intermediate sizes.These results demonstrate the presence of constraints bounding the caniform distribution at large and small body sizes, stabilizing the distribution through time, which stands in contrast to a broader mammalian pattern. At a finer phylogenetic scale, subclades within intermediate size classes display proportions that are significantly different from unbiased, with several clades previously cited as examples of “Cope's Rule” showing biased increases in size, and basal mustelids (badgers, and allied genera), Mephitidae (skunks), and Vulpini (“foxes”) exhibiting biased decreases. The caniform pattern is therefore the result of superimposed, clade-specific trajectories, demonstrating that the inferred dynamics of body size evolution and even the direction of trends in body size evolution within the Caniformia, and for mammals in general, depend on the hierarchical scale of the analysis.

Bergmann's rule is invalid

1987 ◽  
Vol 65 (4) ◽  
pp. 1035-1038 ◽  
Author(s):  
Valerius Geist
Keyword(s):  
Body Size ◽  
Surface Area ◽  
Small Body ◽  
Bergmann’S Rule ◽  
Bergmann's Rule ◽  
Large Mammals ◽  
Annual Productivity ◽  
Body Sizes ◽  
Growth Correlations

Bergmann's rule, claiming that in homeotherms body size increases inversely with temperature so that, intraspecifically, body size increases latitudinally, is not valid, nor is the explanation of this rule. In large mammals body size at first increases with latitude, but then reverses between 53 and 65° N, so that small body sizes occur at the lowest and highest latitudes. This is predicted by the hypothesis that body size follows the duration of the annual productivity pulse, so that body size is a function of availability of nutrients and energy during periods of growth. Correlations between body size and temperature are shown to be spurious. If reduction in relative surface area is indeed an adaptation to conserve heat, then mammals should increase in size from south to north at rates two orders of magnitude greater than they do. Bergmann's rule has no basis in fact or theory.

scholarly journals Phylogeny of the damselfishes (Pomacentridae) and patterns of asymmetrical diversification in body size and feeding ecology

2021 ◽  
Author(s):  
Charlene L. McCord ◽  
W. James Cooper ◽  
Chloe M. Nash ◽  
Mark W. Westneat
Keyword(s):  
Body Size ◽  
Feeding Ecology ◽  
Molecular Phylogenetics ◽  
Evolutionary Ecology ◽  
Fish Assemblages ◽  
Mitochondrial Gene ◽  
Small Body ◽  
Evolutionary Diversification ◽  
Body Sizes ◽  
And Function

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.

scholarly journals The paradox of inverted biomass pyramids in kelp forest fish communities

2016 ◽  
Vol 283 (1833) ◽  
pp. 20160816 ◽  
Author(s):  
Rowan Trebilco ◽  
Nicholas K. Dulvy ◽  
Sean C. Anderson ◽  
Anne K. Salomon
Keyword(s):  
Body Size ◽  
Trophic Position ◽  
Small Body ◽  
Large Body ◽  
Kelp Forest ◽  
Fish Communities ◽  
Reef Fishes ◽  
Fish Muscle ◽  
Mass Ratio ◽  
Body Sizes

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.

scholarly journals Will giant polar amphipods be first to fare badly in an oxygen-poor ocean? Testing hypotheses linking oxygen to body size

2019 ◽  
Vol 374 (1778) ◽  
pp. 20190034 ◽  
Author(s):  
John I. Spicer ◽  
Simon A. Morley
Keyword(s):  
Climate Change ◽  
Body Size ◽  
Marine Invertebrates ◽  
Global Climate ◽  
Small Body ◽  
Oxygen Limitation ◽  
Amphipod Species ◽  
Evolutionary Innovation ◽  
Wide Range ◽  
Body Sizes

It has been suggested that giant Antarctic marine invertebrates will be particularly vulnerable to declining O 2 levels as our ocean warms in line with current climate change predictions. Our study provides some support for this oxygen limitation hypothesis, with larger body sizes being generally more sensitive to O 2 reductions than smaller body sizes. However, it also suggests that the overall picture is a little more complex. We tested predictions from three different, but overlapping, O 2 -related hypotheses accounting for gigantism, using four Antarctic amphipod species encompassing a wide range of body sizes. We found a significant effect of body size, but also of species, in their respiratory responses to acutely declining O 2 tensions. The more active lifestyle of intermediate-sized Prostebbingia brevicornis was supported by a better respiratory performance than predicted by the oxygen limitation hypothesis alone, but consistent with the symmorphosis hypothesis. We suggest that giant polar amphipods are likely to be some of the first to fare badly in an O 2 -poor ocean. However, the products of past evolutionary innovation, such as respiratory pigments that enhance O 2 -transport and novel gas exchange structures, may in some species offset any respiratory disadvantages of either large or small body size. This article is part of the theme issue ‘Physiological diversity, biodiversity patterns and global climate change: testing key hypotheses involving temperature and oxygen’.

scholarly journals Analysis of quantitative inheritance of body size in mice IV. An Attempt to isolate polygenes

1961 ◽  
Vol 2 (1) ◽  
pp. 25-32 ◽  
Author(s):  
C. K. Chai
Keyword(s):  
Body Size ◽  
Small Body ◽  
Quantitative Inheritance ◽  
Breeding Scheme ◽  
Body Sizes ◽  
Selection For ◽  
Large Genes

The isolation of single inheritance units affecting body size in mice has been attempted. By using Large and Small mice as the parental strains, a breeding scheme has been carried out by repeated backcrossing to each strain with selection for both large and small body sizes in each backcross. The selections were started from the second backcross generations. The Small backcross was carried to the seventh generation and the Large to the fifth. Based on analysis of the means and variances for the parental strains and the backcross generations, it is tentatively concluded that a small number of, if not single, inheritance units may have been introduced from the Large to the Small mice. The ‘large’ genes appear to be dominant over the ‘small’ genes.

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