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

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.

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3077 ◽  
Author(s):  
Paul M. Oliver ◽  
Amy Iannella ◽  
Stephen J. Richards ◽  
Michael S.Y. Lee

AimsMountain ranges in the tropics are characterised by high levels of localised endemism, often-aberrant evolutionary trajectories, and some of the world’s most diverse regional biotas. Here we investigate the evolution of montane endemism, ecology and body size in a clade of direct-developing frogs (Choerophryne,Microhylidae) from New Guinea.MethodsPhylogenetic relationships were estimated from a mitochondrial molecular dataset using Bayesian and maximum likelihood approaches. Ancestral state reconstruction was used to infer the evolution of elevational distribution, ecology (indexed by male calling height), and body size, and phylogenetically corrected regression was employed to examine the relationships between these three traits.ResultsWe obtained strong support for a monophyletic lineage comprising the majority of taxa sampled. Within this clade we identified one subclade that appears to have diversified primarily in montane habitats of the Central Cordillera (>1,000 m a.s.l.), with subsequent dispersal to isolated North Papuan Mountains. A second subclade (characterised by moderately to very elongated snouts) appears to have diversified primarily in hill forests (<1,000 m a.s.l.), with inferred independent upwards colonisations of isolated montane habitats, especially in isolated North Papuan Mountains. We found no clear relationship between extremely small body size (adult SVL less than 15 mm) and elevation, but a stronger relationship with ecology—smaller species tend to be more terrestrial.ConclusionsOrogeny and climatic oscillations have interacted to generate high montane biodiversity in New Guinea via both localised diversification within montane habitats (centric endemism) and periodic dispersal across lowland regions (eccentric endemism). The correlation between extreme miniaturisation and terrestrial habits reflects a general trend in frogs, suggesting that ecological or physiological constraints limit niche usage by miniaturised frogs, even in extremely wet environments such as tropical mountains.


2017 ◽  
Author(s):  
Paul M Oliver ◽  
Amy Iannella ◽  
Stephen J Richards ◽  
Michael S.Y Lee

Aims. Mountain ranges in the tropics are characterised by high levels of localised endemism, often-aberrant evolutionary trajectories, and some of the world’s most diverse regional biotas. Here we investigate the evolution of montane endemism, ecology and body size in a clade of direct-developing frogs (Choerophryne, Microhylidae) from New Guinea. Methods. Phylogenetic relationships were estimated from a mitochondrial molecular dataset using Bayesian and maximum likelihood approaches. Ancestral state reconstruction was used to infer the evolution of elevational distribution, ecology (indexed by male calling height), and body size, and phylogenetically corrected regression was employed to examine the relationships between these three traits. Results. We obtained strong support for a monophyletic lineage comprising the majority of taxa sampled. Within this clade we identified one subclade that appears to have diversified primarily in montane habitats of the Central Cordillera (> 1000 m. a.s.l), with subsequent dispersal to isolated North Papuan Mountains. A second subclade (characterised by moderately to very elongated snouts) appears to have diversified primarily in hill forests (< 1000 m a.s.l.), with inferred independent upwards colonisations of isolated montane habitats, especially in isolated North Papuan Mountains. We found no clear relationship between extremely small body size (adult SVL less than 15mm) and elevation, but a stronger relationship with ecology – smaller species tend to be more terrestrial. Conclusions. Orogeny and climatic oscillations have interacted to generate high montane biodiversity in New Guinea via both localised diversification within montane habitats (centric endemism) and periodic dispersal across lowland regions (eccentric endemism). The correlation between extreme miniaturisation and terrestrial habits reflects a general trend in frogs, suggesting that ecological or physiological constraints limit niche usage by miniaturised frogs, even in extremely wet environments such as tropical mountains.


2020 ◽  
Vol 40 (3) ◽  
pp. 325-329
Author(s):  
Joshua T Fields ◽  
Hayden K Mullen ◽  
Clayr M Kroenke ◽  
Kyla A Salomon ◽  
Abby J Craft ◽  
...  

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.


2020 ◽  
Vol 66 (5) ◽  
pp. 539-553
Author(s):  
Lucas N Weaver ◽  
David M Grossnickle

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 (&lt;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.


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.


Paleobiology ◽  
2008 ◽  
Vol 34 (4) ◽  
pp. 553-562 ◽  
Author(s):  
John A. Finarelli

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.


1987 ◽  
Vol 65 (4) ◽  
pp. 1035-1038 ◽  
Author(s):  
Valerius Geist

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.


2017 ◽  
Author(s):  
Paul M Oliver ◽  
Amy Iannella ◽  
Stephen J Richards ◽  
Michael S.Y Lee

Aims. Mountain ranges in the tropics are characterised by high levels of localised endemism, often-aberrant evolutionary trajectories, and some of the world’s most diverse regional biotas. Here we investigate the evolution of montane endemism, ecology and body size in a clade of direct-developing frogs (Choerophryne, Microhylidae) from New Guinea. Methods. Phylogenetic relationships were estimated from a mitochondrial molecular dataset using Bayesian and maximum likelihood approaches. Ancestral state reconstruction was used to infer the evolution of elevational distribution, ecology (indexed by male calling height), and body size, and phylogenetically corrected regression was employed to examine the relationships between these three traits. Results. We obtained strong support for a monophyletic lineage comprising the majority of taxa sampled. Within this clade we identified one subclade that appears to have diversified primarily in montane habitats of the Central Cordillera (> 1000 m. a.s.l), with subsequent dispersal to isolated North Papuan Mountains. A second subclade (characterised by moderately to very elongated snouts) appears to have diversified primarily in hill forests (< 1000 m a.s.l.), with inferred independent upwards colonisations of isolated montane habitats, especially in isolated North Papuan Mountains. We found no clear relationship between extremely small body size (adult SVL less than 15mm) and elevation, but a stronger relationship with ecology – smaller species tend to be more terrestrial. Conclusions. Orogeny and climatic oscillations have interacted to generate high montane biodiversity in New Guinea via both localised diversification within montane habitats (centric endemism) and periodic dispersal across lowland regions (eccentric endemism). The correlation between extreme miniaturisation and terrestrial habits reflects a general trend in frogs, suggesting that ecological or physiological constraints limit niche usage by miniaturised frogs, even in extremely wet environments such as tropical mountains.


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.


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