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.

scholarly journals The multi-peak adaptive landscape of crocodylomorph body size evolution

2018 ◽  
Author(s):  
Pedro L. Godoy ◽  
Roger B. J. Benson ◽  
Mario Bronzati ◽  
Richard J. Butler
Keyword(s):  
Body Size ◽  
Abiotic Factors ◽  
Large Body ◽  
Size Increase ◽  
Adaptive Landscape ◽  
Evolutionary Trend ◽  
Size Evolution ◽  
Size Disparity ◽  
Body Sizes ◽  
Body Size Evolution

AbstractBackgroundLittle is known about the long-term patterns of body size evolution in Crocodylomorpha, the > 200-million-year-old group that includes living crocodylians and their extinct relatives. Extant crocodylians are mostly large-bodied (3–7 m) predators. However, extinct crocodylomorphs exhibit a wider range of phenotypes, and many of the earliest taxa were much smaller (< 1.2 m). This suggests a pattern of size increase through time that could be caused by multi-lineage evolutionary trends of size increase or by selective extinction of small-bodied species. In this study, we characterise patterns of crocodylomorph body size evolution using a model fitting-approach (with cranial measurements serving as proxies). We also estimate body size disparity through time and quantitatively test hypotheses of biotic and abiotic factors as potential drivers of crocodylomorph body size evolution.ResultsCrocodylomorphs reached an early peak in body size disparity during the Late Jurassic, and underwent essentially continually decreases in disparity since then. A multi-peak Ornstein-Uhlenbeck model outperforms all other evolutionary models fitted to our data (including both uniform and non-uniform), indicating that the macroevolutionary dynamics of crocodylomorph body size are better described within the concept of an adaptive landscape, with most body size variation emerging after shifts to new macroevolutionary regimes (analogous to adaptive zones). We did not find support for a consistent evolutionary trend towards larger sizes among lineages (i.e., Cope’s rule), or strong correlations of body size with climate. Instead, the intermediate to large body sizes of some crocodylomorphs are better explained by group-specific adaptations. In particular, the evolution of a more aquatic lifestyle (especially marine) correlates with increases in average body size, though not without exceptions.ConclusionsShifts between macroevolutionary regimes provide a better explanation of crocodylomorph body size evolution than do climatic factors, suggesting a central role for lineage-specific adaptations rather than climatic forcing. Shifts leading to larger body sizes occurred in most aquatic and semi-aquatic groups. This, combined with extinctions of groups occupying smaller body size regimes (particularly during the Late Cretaceous and Cenozoic), gave rise to the upward-shifted body size distribution of extant crocodylomorphs compared to their smaller-bodied terrestrial ancestors.

scholarly journals Migratory lineages rapidly evolve larger body sizes than non-migratory relatives in ray-finned fishes

2020 ◽  
Vol 287 (1918) ◽  
pp. 20192615 ◽  
Author(s):  
Michael D. Burns ◽  
Devin D. Bloom
Keyword(s):  
Body Size ◽  
Life History Theory ◽  
Environmental Heterogeneity ◽  
Empirical Studies ◽  
Adaptive Landscape ◽  
Migratory Species ◽  
Size Evolution ◽  
Body Sizes ◽  
Body Size Evolution ◽  
First Time

Migratory animals respond to environmental heterogeneity by predictably moving long distances in their lifetime. Migration has evolved repeatedly in animals, and many adaptations are found across the tree of life that increase migration efficiency. Life-history theory predicts that migratory species should evolve a larger body size than non-migratory species, and some empirical studies have shown this pattern. A recent study analysed the evolution of body size between diadromous and non-diadromous shads, herrings, anchovies and allies, finding that species evolved larger body sizes when adapting to a diadromous lifestyle. It remains unknown whether different fish clades adapt to migration similarly. We used an adaptive landscape framework to explore body size evolution for over 4500 migratory and non-migratory species of ray-finned fishes. By fitting models of macroevolution, we show that migratory species are evolving towards a body size that is larger than non-migratory species. Furthermore, we find that migratory lineages evolve towards their optimal body size more rapidly than non-migratory lineages, indicating body size is a key adaption for migratory fishes. Our results show, for the first time, that the largest vertebrate radiation on the planet exhibited strong evolutionary determinism when adapting to a migratory lifestyle.

scholarly journals Rates of ecological divergence and body size evolution are correlated with species diversification in scaly tree ferns

2016 ◽  
Vol 283 (1834) ◽  
pp. 20161098 ◽  
Author(s):  
Santiago Ramírez-Barahona ◽  
Josué Barrera-Redondo ◽  
Luis E. Eguiarte
Keyword(s):  
Species Richness ◽  
Body Size ◽  
Ecological Niche ◽  
Morphological Evolution ◽  
Ecological Niches ◽  
Species Diversification ◽  
Tree Ferns ◽  
Size Evolution ◽  
Body Sizes ◽  
Body Size Evolution

Variation in species richness across regions and between different groups of organisms is a major feature of evolution. Several factors have been proposed to explain these differences, including heterogeneity in the rates of species diversification and the age of clades. It has been frequently assumed that rapid rates of diversification are coupled to high rates of ecological and morphological evolution, leading to a prediction that remains poorly explored for most species: the positive association between ecological niche divergence, morphological evolution and species diversification. We combined a time-calibrated phylogeny with distribution, ecological and body size data for scaly tree ferns (Cyatheaceae) to test whether rates of species diversification are predicted by the rates at which clades have evolved distinct ecological niches and body sizes. We found that rates of species diversification are positively correlated with rates of ecological and morphological evolution, with rapidly diversifying clades also showing rapidly evolving ecological niches and body sizes. Our results show that rapid diversification of scaly tree ferns is associated with the evolution of species with comparable morphologies that diversified into similar, yet distinct, environments. This suggests parallel evolutionary pathways opening in different tropical regions whenever ecological and geographical opportunities arise. Accordingly, rates of ecological niche and body size evolution are relevant to explain the current patterns of species richness in this ‘ancient’ fern lineage across the tropics.

scholarly journals Rates and modes of body size evolution in early carnivores and herbivores: a case study from Captorhinidae

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1555 ◽  
Author(s):  
Neil Brocklehurst
Keyword(s):  
Body Size ◽  
Rate Variation ◽  
Basal Node ◽  
Rates Of Evolution ◽  
Size Evolution ◽  
High Fibre ◽  
Body Sizes ◽  
Adaptive Peak ◽  
Quantitative Examination ◽  
Body Size Evolution

Body size is an extremely important characteristic, impacting on a variety of ecological and life-history traits. It is therefore important to understand the factors which may affect its evolution, and diet has attracted much interest in this context. A recent study which examined the evolution of the earliest terrestrial herbivores in the Late Carboniferous and Early Permian concluded that in the four herbivorous clades examined there was a trend towards increased body size, and that this increase was more substantial than that observed in closely related carnivorous clades. However, this hypothesis was not based on quantitative examination, and phylogenetic comparative methods provide a more robust means of testing such hypotheses. Here, the evolution of body size within different dietary regimes is examined in Captorhinidae, the most diverse and longest lived of these earliest high fibre herbivores. Evolutionary models were fit to their phylogeny to test for variation in rate and mode of evolution between the carnivorous and herbivorous members of this clade, and an analysis of rate variation throughout the tree was carried out. Estimates of ancestral body sizes were calculated in order to compare the rates and direction of evolution of lineages with different dietary regimes. Support for the idea that the high fibre herbivores within captorhinids are being drawn to a higher adaptive peak in body size than the carnivorous members of this clade is weak. A shift in rates of body size evolution is identified, but this does not coincide with the evolution of high-fibre herbivory, instead occurring earlier in time and at a more basal node. Herbivorous lineages which show an increase in size are not found to evolve at a faster rate than those which show a decrease; in fact, it is those which experience a size decrease which evolve at higher rates. It is possible the shift in rates of evolution is related to the improved food processing ability of the more derived captorhinids rather than a shift in diet, but the evidence for this is circumstantial.

scholarly journals Rates and modes of body size evolution in early carnivores and herbivores: a case study from Captorhinidae

2015 ◽  
Author(s):  
Neil Brocklehurst
Keyword(s):  
Body Size ◽  
Rate Variation ◽  
Basal Node ◽  
Rates Of Evolution ◽  
Size Evolution ◽  
High Fibre ◽  
Body Sizes ◽  
Adaptive Peak ◽  
Quantitative Examination ◽  
Body Size Evolution

Body size is an extremely important characteristic, impacting on a variety of ecological and life-history traits. It is therefore important to understand the factors which may affect its evolution, and diet has attracted much interest in this context. A recent study, examining the evolution of the earliest terrestrial herbivores in the Late Carboniferous and Early Permian, concluded that in the four herbivorous clades examined there was a trend towards increased body size, and that this increase was more substantial than that observed in closely related carnivorous clades. However, this hypothesis was not based on quantitative examination, and phylogenetic comparative methods provide a more robust means of testing such hypotheses. Here, the evolution of body size within different dietary regimes is examined in Captorhinidae, the most diverse and longest lived of these earliest high fibre herbivores. Evolutionary models were fit to their phylogeny to test for variation in rate and mode of evolution between the carnivorous and herbivorous members of this clade, and an analysis of rate variation throughout the tree was carried out. Estimates of ancestral body sizes were calculated in order to compare the rates and direction of evolution of lineages with different dietary regimes. Support for the idea that the high fibre herbivores within captorhinids are being drawn to a higher adaptive peak in body size than the carnivorous members of this clade is weak. A shift in rates of body size evolution is identified, but this does not coincide with the evolution of high-fibre herbivory, instead occurring earlier in time and at a more basal node. Herbivorous lineages which show an increase in size are not found to evolve at a faster rate than those which show a decrease; in fact it is those which experience a size decrease which evolve at significantly higher rates. The opposite is true of the carnivorous lineages, suggesting that in captorhinids it is the carnivores which show the greater trend towards increased body size. It is possible the shift in rates of evolution is related to the improved food processing ability of the more derived captorhinids rather than a shift in diet, but the evidence for this is circumstantial.

scholarly journals New insights into the genetic mechanisms of body size evolution in Carnivora

2020 ◽  
Author(s):  
Xin Huang ◽  
Di Sun ◽  
Tianzhen Wu ◽  
Xing Liu ◽  
Shixia Xu ◽  
...  
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Rapid Evolution ◽  
Large Body ◽  
The Body ◽  
Molecular Evidence ◽  
Size Evolution ◽  
Body Size Evolution

Abstract Background The range of body sizes in Carnivora is unparalleled in any other mammalian order, with more than 130,000 times in body mass and 50 times in length. However, the molecular mechanisms underlying the huge difference in body size of Carnivora have not been explored so far. Results Herein, we performed a comparative genomics analysis of 20 carnivores to explore the genetic basis of great body size variation in carnivores. Phylogenetic generalized least squares (PGLS) revealed that 337 genes were significantly related to both head body length and body mass, these genes were defined as body size associated genes (BSAGs). Fourteen positively related BSAGs were found to be associated with obesity and three of which were identified to be under rapid evolution in the extremely large body-sized carnivores, which suggested that these obesity-related BSAGs might have driven the body size expansion in carnivores. Interestingly, 100 BSAGs were examined to be associated with cancer control in carnivores, particularly 15 cancer-related genes were found to be under rapid evolution in extremely large carnivores. These results strongly suggested that large body-sized carnivores might have evolved effective mechanism to resist cancer, which could be regarded as molecular evidence to support for the Peto’s paradox. For small carnivores, we identified 15 rapidly evolving genes and found six genes with fixed amino acid changes that were reported to reduce body size. Conclusion This study brings new insights into the molecular mechanisms that drove the diversifying evolution of body size in carnivores, and provides new target genes for exploring the mysteries of body size evolution in mammals.

scholarly journals Fitting macroevolutionary models to phylogenies: an example using vertebrate body sizes

1998 ◽  
Vol 68 (1) ◽  
pp. 3-18 ◽  
Author(s):  
Arne Ø. Mooers ◽  
Dolph Schluter
Keyword(s):  
Body Size ◽  
Data Sets ◽  
Size Evolution ◽  
Family Level ◽  
Free Model ◽  
Body Sizes ◽  
Body Size Evolution ◽  
Species Specific ◽  
The Relationship ◽  
Best Fit

How do traits change through time and with speciation? We present a simple and generally applicable method for comparing various models of the macroevolution of traits within a maximum likelihood framework. We illustrate four such models: 1) variance among species accumulates in direct proportion to time separating them (gradual model); 2) variation accumulates with the number of speciation events separating them (speciational model); 3) differences between species are unrelated to phylogenetic relatedness (pitchfork model); and 4) a free model where the trait evolves at its own idiosyncratic rate among lineages. Using species-specific body size, we compare the four models across two data sets: twenty-one clades of vertebrate species, and two clades of bird families. For the twenty-one vertebrate trees, the pitchfork model is most successful, though not significantly, and the most successful by far for the youngest clades. The speciational model seems to be preferred for older clades. For both clades of bird families, the speciational model offers the best fit to family-level body size evolution. However, the pitchfork model does much worse for one clade than for the other, suggesting a difference in the relationship between diversification and body-size evolution in the two groups. These examples highlight some possibilities afforded by this simple approach.

scholarly journals The evolution of island gigantism and body size variation in tortoises and turtles

2011 ◽  
Vol 7 (4) ◽  
pp. 558-561 ◽  
Author(s):  
Alexander L. Jaffe ◽  
Graham J. Slater ◽  
Michael E. Alfaro
Keyword(s):  
Body Size ◽  
Size Variation ◽  
Body Size Variation ◽  
Size Evolution ◽  
Seychelles Islands ◽  
Body Sizes ◽  
Terrestrial Environments ◽  
Size Diversity ◽  
Phylogenetic Framework ◽  
Body Size Evolution

Extant chelonians (turtles and tortoises) span almost four orders of magnitude of body size, including the startling examples of gigantism seen in the tortoises of the Galapagos and Seychelles islands. However, the evolutionary determinants of size diversity in chelonians are poorly understood. We present a comparative analysis of body size evolution in turtles and tortoises within a phylogenetic framework. Our results reveal a pronounced relationship between habitat and optimal body size in chelonians. We found strong evidence for separate, larger optimal body sizes for sea turtles and island tortoises, the latter showing support for the rule of island gigantism in non-mammalian amniotes. Optimal sizes for freshwater and mainland terrestrial turtles are similar and smaller, although the range of body size variation in these forms is qualitatively greater. The greater number of potential niches in freshwater and terrestrial environments may mean that body size relationships are more complicated in these habitats.

scholarly journals Long-term patterns of body mass and stature evolution within the hominin lineage

2017 ◽  
Vol 4 (11) ◽  
pp. 171339 ◽  
Author(s):  
Manuel Will ◽  
Adrián Pablos ◽  
Jay T. Stock
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Homo Sapiens ◽  
Small Body ◽  
Relative Size ◽  
Size Variation ◽  
Adaptive Strategy ◽  
Middle Pleistocene ◽  
Body Sizes

Body size is a central determinant of a species' biology and adaptive strategy, but the number of reliable estimates of hominin body mass and stature have been insufficient to determine long-term patterns and subtle interactions in these size components within our lineage. Here, we analyse 254 body mass and 204 stature estimates from a total of 311 hominin specimens dating from 4.4 Ma to the Holocene using multi-level chronological and taxonomic analytical categories. The results demonstrate complex temporal patterns of body size variation with phases of relative stasis intermitted by periods of rapid increases. The observed trajectories could result from punctuated increases at speciation events, but also differential proliferation of large-bodied taxa or the extinction of small-bodied populations. Combined taxonomic and temporal analyses show that in relation to australopithecines, early Homo is characterized by significantly larger average body mass and stature but retains considerable diversity, including small body sizes. Within later Homo , stature and body mass evolution follow different trajectories: average modern stature is maintained from ca 1.6 Ma, while consistently higher body masses are not established until the Middle Pleistocene at ca 0.5–0.4 Ma, likely caused by directional selection related to colonizing higher latitudes. Selection against small-bodied individuals (less than 40 kg; less than 140 cm) after 1.4 Ma is associated with a decrease in relative size variability in later Homo species compared with earlier Homo and australopithecines. The isolated small-bodied individuals of Homo naledi ( ca 0.3 Ma) and Homo floresiensis ( ca 100–60 ka) constitute important exceptions to these general patterns, adding further layers of complexity to the evolution of body size within the genus Homo . At the end of the Late Pleistocene and Holocene, body size in Homo sapiens declines on average, but also extends to lower limits not seen in comparable frequency since early Homo .

Oligo-Miocene climate change and mammal body-size evolution in the northwest United States: a test of Bergmann's Rule

Paleobiology ◽  
10.1666/13006 ◽  
2013 ◽  
Vol 39 (4) ◽  
pp. 648-661 ◽  
Author(s):  
John D. Orcutt ◽  
Samantha S. B. Hopkins
Keyword(s):  
United States ◽  
Body Size ◽  
Body Mass ◽  
Global Climate ◽  
Climatic Conditions ◽  
Bergmann’S Rule ◽  
Bergmann's Rule ◽  
Complex Interactions ◽  
Size Evolution ◽  
Body Size Evolution

Whether or not climate plays a causal role in mammal body-size evolution is one of the longest-standing debates in ecology. Bergmann's Rule, the longest-standing modeladdressing this topic, posits that geographic body-mass patterns are driven by temperature, whereas subsequent research has suggested that other ecological variables, particularly precipitation and seasonality, may be the major drivers of body-size evolution. While paleoecological data provide a unique and crucial perspective on this debate, paleontological tests of Bergmann's rule and its corollaries have been scarce. We present a study of body-size evolution in three ecologically distinct families of mammal (equids, canids, and sciurids) during the Oligo-Miocene of the northwest United States, an ideal natural laboratory for such studies because of its rich fossil and paleoclimatic records. Body-size trends are different in all three groups, and in no case is a significant relationship observed between body size and any climatic variable, counter to what has been observed in modern ecosystems. We suggest that for most of the Cenozoic, at least in the Northwest, body mass has not been driven by any one climatic factor but instead has been the product of complex interactions between organisms and their environments, though the nature of these interactions varies from taxon to taxon. The relationship that exists between climate and body size in many groups of modern mammals, therefore, is the exception to the rule and may be the product of an exceptionally cool and volatile global climate. As anthropogenic global warming continues and ushers in climatic conditions more comparable to earlier intervals of the Cenozoic than to the modern day, models of corresponding biotic variables such as body size may lose predictive power if they do not incorporate paleoecological data.

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