Do convergent ecomorphs evolve through convergent morphological pathways? Cranial shape evolution in fossil hyaenids and borophagine canids (Carnivora, Mammalia)

Paleobiology ◽  
2011 ◽  
Vol 37 (3) ◽  
pp. 470-489 ◽  
Author(s):  
Zhijie Jack Tseng ◽  
Xiaoming Wang
Keyword(s):  
Convergent Evolution ◽  
Shape Change ◽  
Morphological Evolution ◽  
Shape Evolution ◽  
Deep Time ◽  
Phylogenetic Constraint ◽  
Mechanisms Of Adaptation ◽  
Evolutionary Pathways ◽  
Length Reduction ◽  
Cranial Shape

Cases of convergent evolution, particularly within ecomorphological contexts, are instructive in identifying universally adaptive morphological features across clades. Tracing of evolutionary pathways by which ecomorphological convergence takes place can further reveal mechanisms of adaptation, which may be strongly influenced by phylogeny. Ecomorphologies of carnivorous mammals represent some of the most outstanding cases of convergent evolution in the Cenozoic radiation of mammals. This study examined patterns of cranial shape change in the dog (Canidae) and hyena (Hyaenidae) families, in order to compare the evolutionary pathways that led to the independent specialization of bone-cracking hypercarnivores within each clade. Geometric morphometrics analyses of cranial shape in fossil hyaenids and borophagine canids provided evidence for deep-time convergence in morphological pathways toward the independent evolution of derived bone-crackers. Both clades contained stem members with plesiomorphic generalist/omnivore cranial shapes, which evolved into doglike species along parallel pathways of shape change. The evolution of specialized bone-crackers from these doglike forms, however, continued under the constraint of a full cheek dentition and restriction on rostrum length reduction in canids, but not hyaenids. Functionally, phylogenetic constraint may have limited borophagine canids to crack bones principally with their carnassial instead of the third premolar as in hyaenids, but other cranial shape changes associated with durophagy nevertheless evolved in parallel in the two lineages. Size allometry was not a major factor in cranial shape evolution in either lineage, supporting the interpretation of functional demands as drivers for the observed convergence. The comparison between borophagines and hyaenids showed that differential effects of alternative functional “solutions” that arise during morphological evolution may be multiplied with processes of the “macroevolutionary ratchet” already in place to further limit the evolutionary pathways available to specialized lineages.

scholarly journals An integrative method for testing form–function linkages and reconstructed evolutionary pathways of masticatory specialization

2015 ◽  
Vol 12 (107) ◽  
pp. 20150184 ◽  
Author(s):  
Z. Jack Tseng ◽  
John J. Flynn
Keyword(s):  
Mechanical Properties ◽  
Morphological Evolution ◽  
Integrative Approach ◽  
Deep Time ◽  
Integrate Form ◽  
Functional Changes ◽  
Form And Function ◽  
Form Function ◽  
Evolutionary Pathways ◽  
And Function

Morphology serves as a ubiquitous proxy in macroevolutionary studies to identify potential adaptive processes and patterns. Inferences of functional significance of phenotypes or their evolution are overwhelmingly based on data from living taxa. Yet, correspondence between form and function has been tested in only a few model species, and those linkages are highly complex. The lack of explicit methodologies to integrate form and function analyses within a deep-time and phylogenetic context weakens inferences of adaptive morphological evolution, by invoking but not testing form–function linkages. Here, we provide a novel approach to test mechanical properties at reconstructed ancestral nodes/taxa and the strength and direction of evolutionary pathways in feeding biomechanics, in a case study of carnivorous mammals. Using biomechanical profile comparisons that provide functional signals for the separation of feeding morphologies, we demonstrate, using experimental optimization criteria on estimation of strength and direction of functional changes on a phylogeny, that convergence in mechanical properties and degree of evolutionary optimization can be decoupled. This integrative approach is broadly applicable to other clades, by using quantitative data and model-based tests to evaluate interpretations of function from morphology and functional explanations for observed macroevolutionary pathways.

scholarly journals The macroevolutionary consequences of phenotypic integration: from development to deep time

2014 ◽  
Vol 369 (1649) ◽  
pp. 20130254 ◽  
Author(s):  
A. Goswami ◽  
J. B. Smaers ◽  
C. Soligo ◽  
P. D. Polly
Keyword(s):  
Random Walk ◽  
Convergent Evolution ◽  
Significant Variation ◽  
Reproductive Strategies ◽  
Morphological Evolution ◽  
Evolutionary Change ◽  
Phenotypic Integration ◽  
Response To Selection ◽  
Deep Time ◽  
Rates Of Evolution

Phenotypic integration is a pervasive characteristic of organisms. Numerous analyses have demonstrated that patterns of phenotypic integration are conserved across large clades, but that significant variation also exists. For example, heterochronic shifts related to different mammalian reproductive strategies are reflected in postcranial skeletal integration and in coordination of bone ossification. Phenotypic integration and modularity have been hypothesized to shape morphological evolution, and we extended simulations to confirm that trait integration can influence both the trajectory and magnitude of response to selection. We further demonstrate that phenotypic integration can produce both more and less disparate organisms than would be expected under random walk models by repartitioning variance in preferred directions. This effect can also be expected to favour homoplasy and convergent evolution. New empirical analyses of the carnivoran cranium show that rates of evolution, in contrast, are not strongly influenced by phenotypic integration and show little relationship to morphological disparity, suggesting that phenotypic integration may shape the direction of evolutionary change, but not necessarily the speed of it. Nonetheless, phenotypic integration is problematic for morphological clocks and should be incorporated more widely into models that seek to accurately reconstruct both trait and organismal evolution.

scholarly journals Cranial shape evolution of extant and fossil crocodile newts and its relation to reproduction and ecology

2020 ◽  
Vol 237 (2) ◽  
pp. 285-300 ◽  
Author(s):  
Peter Pogoda ◽  
Marcus Zuber ◽  
Tilo Baumbach ◽  
Rainer R. Schoch ◽  
Alexander Kupfer
Keyword(s):  
Shape Evolution ◽  
Cranial Shape

Warning signals promote morphological diversification in fossorial uropeltid snakes (Squamata: Uropeltidae)

2020 ◽  
Author(s):  
Vivek Philip Cyriac ◽  
Ullasa Kodandaramaiah
Keyword(s):  
Body Size ◽  
Free Space ◽  
Morphological Evolution ◽  
Environmental Constraints ◽  
Shape Evolution ◽  
Head Shape ◽  
Warning Signals ◽  
Morphological Diversification ◽  
Niche Expansion ◽  
Antipredator Defences

Abstract Many species possess warning colourations that signal unprofitability to predators. Warning colourations are also thought to provide prey with a ‘predator-free space’ and promote niche expansion. However, how such strategies release a species from environmental constraints and facilitate niche expansion is not clearly understood. Fossoriality in reptiles imposes several morphological limits on head and body size to facilitate burrowing underground, but many fossorial snakes live close to the surface and occasionally move above ground, exposing them to predators. In such cases, evolving antipredator defences that reduce predation on the surface could potentially relax the morphological constraints associated with fossoriality and promote morphological diversification. Fossorial uropeltid snakes possess varying degrees of conspicuous warning colourations that reduce avian predation when active above ground. We predicted that species with more conspicuous colourations will exhibit more robust body forms and show faster rates of morphological evolution because constraints imposed by fossoriality are relaxed. Using a comparative phylogenetic approach on the genus Uropeltis, we show that more conspicuous species tend to have more robust morphologies and have faster rates of head-shape evolution. Overall, we find that the evolution of warning colourations in Uropeltis can facilitate niche expansion by influencing rates of morphological diversification.

scholarly journals Do Coral Reefs Promote Morphological Diversification? Exploration of Habitat Effects on Labrid Pharyngeal Jaw Evolution in the Era of Big Data

2019 ◽  
Vol 59 (3) ◽  
pp. 696-704 ◽  
Author(s):  
Kory M Evans ◽  
Keiffer L Williams ◽  
Mark W Westneat
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Morphological Evolution ◽  
Morphological Data ◽  
Shape Evolution ◽  
Micro Computed Tomography ◽  
Functional Variation ◽  
Morphological Diversification ◽  
Marine Habitats ◽  
Pharyngeal Jaw

Abstract Coral reefs are complex marine habitats that have been hypothesized to facilitate functional specialization and increased rates of functional and morphological evolution. Wrasses (Labridae: Percomorpha) in particular, have diversified extensively in these coral reef environments and have evolved adaptations to further exploit reef-specific resources. Prior studies have found that reef-dwelling wrasses exhibit higher rates of functional evolution, leading to higher functional variation than in non-reef dwelling wrasses. Here, we examine this hypothesis in the lower pharyngeal tooth plate of 134 species of reef and non-reef-associated labrid fishes using high-resolution morphological data in the form of micro-computed tomography scans and employing three-dimensional geometric morphometrics to quantify shape differences. We find that reef-dwelling wrasses do not differ from non-reef-associated wrasses in morphological disparity or rates of shape evolution. However, we find that some reef-associated species (e.g., parrotfishes and tubelips) exhibit elevated rates of pharyngeal jaw shape evolution and have colonized unique regions of morphospace. These results suggest that while coral reef association may provide the opportunity for specialization and morphological diversification, species must still be able to capitalize on the ecological opportunities to invade novel niche space, and that these novel invasions may prompt rapid rates of morphological evolution in the associated traits that allow them to capitalize on new resources.

An Ivestigation of Temperature-Manipulated Size and Shape Evolution of Preformed Core-Shell Nanoparticles

1999 ◽  
Vol 580 ◽  
Author(s):  
M.M. Maye ◽  
W.X. Zheng ◽  
F.L. Leibowitz ◽  
N.K. Ly ◽  
H.H. Eichelberger ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Ftir Spectroscopy ◽  
Shape Change ◽  
Composite Nanoparticles ◽  
Core Shell ◽  
Shape Evolution ◽  
Shell Nanoparticles ◽  
Size And Shape ◽  
Core Shell Nanoparticles ◽  
Encapsulated Nanoparticles

AbstractThis paper presents a study of heating-induced size and shape change for pre-synthesized composite nanoparticles of ∼2 nm gold cores encapsulated with alkanethiolate monolayers. The results have demonstrated an evolution in size and shape of the nanoparticles towards monodispersed larger core sizes with well-defined and highly-faceted morphologies. The evolved particles were encapsulated with the thiolate shells. The morphological and structural evolutions were characterized using TEM, XRD, UV-Vis and FTIR spectroscopy. While temperature-driven crystal growth is known for non-encapsulated particles, the evolution of the thiolate-encapsulated nanoparticles in solutions into well-defined morphologies represents an intriguing example of temperature manipulations of nanoparticle monodispersity and shape.

Iterative evolution of hypercarnivory in canids (Mammalia: Carnivora): evolutionary interactions among sympatric predators

Paleobiology ◽  
1991 ◽  
Vol 17 (4) ◽  
pp. 340-362 ◽  
Author(s):  
Blaire Van Valkenburgh
Keyword(s):  
South America ◽  
North American ◽  
Morphological Evolution ◽  
Late Oligocene ◽  
The North ◽  
Rapid Diversification ◽  
Competition For Food ◽  
Pattern Of Specialization ◽  
Iterative Evolution ◽  
Length Reduction

Convergent evolution of hypercarnivorous adaptations in canids has occurred a number of times in the last 40 m.y. among distantly related taxa. The adaptations include an increase in carnassial blade length, reduction or loss of post-carnassial molars, and transformation of the talonid of the lower first molar from a basinlike depression into a trenchant, bladelike cusp. Although the diversity of these specialized canids is typically low in past and present communities, it was unusually high during the Late Oligocene of North America and the Pleistocene of South America. These two comparable events provide an opportunity for exploring possible causes of the evolution of hypercarnivory in canids. Plots of generic diversity against time for North American predators reveal a roughly inverse relationship between the number of hypercarnivorous canid taxa and the numbers of other hypercarnivores, such as creodonts, nimravids, mustelids, and amphicyonids. Similarly, the radiation of hypercarnivorous canids in South America occurred at a time of relatively low diversity of other hypercarnivores. Analysis of trophic diversity within the North American carnivore paleoguild before, during, and after the Late Oligocene reveals considerable taxonomic turnover among carnivores because of immigration and speciation. Late Oligocene hypercarnivorous canids appear to have been replaced first by amphicyonids and large mustelids, and then by felids.Despite the repeated tendency of canids to evolve adaptations for hypercarnivory, a canid has yet to appear that is completely catlike, that is, without any post-carnassial molars. This possible constraint on morphological evolution in canids is argued to have resulted, paradoxically, in increased flexibility over evolutionary time and a great potential for rapid diversification and clade survivorship. Finally, it is suggested that the iterative pattern of specialization of the lower molars for meat-slicing that is seen in all families of carnivores, past and present, is probably a result of intraspecific competition for food, perhaps among littermates. This intraspecific selective force is countered by competition among species, since there are limits on the number of sympatric hypercarnivorous species within a single community.

The paradox of gradualism: phyletic evolution in two lineages of lymnocardiid bivalves (Lake Pannon, central Europe)

Paleobiology ◽  
2010 ◽  
Vol 36 (4) ◽  
pp. 592-614 ◽  
Author(s):  
Dana H. Geary ◽  
Gene Hunt ◽  
Imre Magyar ◽  
Holly Schreiber
Keyword(s):  
Shape Change ◽  
Morphological Evolution ◽  
Shell Height ◽  
Model Fitting ◽  
Directional Selection ◽  
Phenotypic Change ◽  
Morphologic Change ◽  
Lake Pannon ◽  
Best Fit

Patterns preserved in the fossil record are of the highest importance in addressing questions about long-term evolutionary processes, yet both the description of pattern and its translation into process can be difficult. With respect to gradual phyletic change, we know that randomly generated sequences may exhibit characteristics of a “trend” apparent patterns, therefore, must be interpreted with caution. Furthermore, even when the claim of a gradual trend can be statistically justified, interpretation of the underlying mechanisms may be challenging. Given that we can observe populations changing rapidly over tens or hundreds of years, it is now more difficult to explain instances of geologically gradual (as opposed to punctuated) change.Here we describe morphologic change in two bivalve lineages from the late Miocene Lake Pannon. We evaluate change according to the model-based methods of Hunt. Both lineages exhibit size increases and shape changes over an interval of nearly 4 million years. Size and two shape variables in the conjungens lineage are best fit by a model of directional evolution; remaining shape variables mostly conform to unbiased random walks. Body-size evolution in the diprosopum lineage is also significantly directional but all shape variables are best fit by the unbiased random walk model; the small number of sampling intervals available for this lineage (n= 6) makes determination of the actual pattern more difficult. Model-fitting results indicate that the parallel trajectories of increasing log shell height over time in the two lineages can be accounted for by an underlying trend shared by both lineages, suggesting that the size increases may be a shared response to the same cause. The pace of phenotypic change, measured as Lynch's Δ, is slower than the neutral expectation for all size and shape traits.Our examples illustrate well the paradox of gradualism; the sequences exhibit significant directional morphological evolution, but rates of change as measured over the long-term are apparently too slow for directional selection or even drift to be the cause. Viewing long-term phenotypic evolution in terms of populations tracking peaks on adaptive landscapes is useful in this context. Such a view allows for intervals of directional selection (during times of peak movement–resulting in the overall trends we can detect) interspersed with intervals of stasis (during times of peak stability–resulting in overall changes that appear to proceed more slowly than the neutral expectation). The paradox of gradualism thus reduces to (1) peak movements and their drivers, which are not restricted in rate as are population-genetic drivers, and (2) the maintenance of stasis, on which no consensus exists.We can identify no environmental parameter in the central European Neogene that exhibits consistent change across the interval of gradual morphologic change. It may be that in Lake Pannon the long-term persistence of generally ameliorating conditions (plentiful resources and habitat space, few predators or competitors) resulted in geologically slow but consistent peak shifts, which in turn facilitated size increase and shape change in these lineages.

The first known riodinid ‘cuckoo’ butterfly reveals deep-time convergence and parallelism in ant social parasites

2020 ◽  
Author(s):  
Lucas A Kaminski ◽  
Luis Volkmann ◽  
Curtis J Callaghan ◽  
Philip J DeVries ◽  
Roger Vila
Keyword(s):  
Life Cycle ◽  
Social Parasitism ◽  
Social Parasites ◽  
Free Living ◽  
Deep Time ◽  
The Third ◽  
The Family ◽  
History Of ◽  
Ant Nest ◽  
Evolutionary Pathways

Abstract Mutualistic interactions between butterflies and ants can evolve into complex social parasitism. ‘Cuckoo’ caterpillars, known only in the Lycaenidae, use multimodal mimetic traits to achieve social integration into ant societies. Here, we present the first known ‘cuckoo’ butterfly in the family Riodinidae. Aricoris arenarum remained in taxonomic limbo for > 80 years, relegated to nomen dubium and misidentified as Aricoris gauchoana. We located lost type material, designated lectotypes and documented the morphology and natural history of the immature stages. The multifaceted life cycle of A. arenarum can be summarized in three phases: (1) females lay eggs close to honeydew-producing hemipterans tended by specific Camponotus ants; (2) free-living caterpillars feed on liquids (honeydew and ant regurgitations); and (3) from the third instar onward, the caterpillars are fed and tended by ants as ‘cuckoos’ inside the ant nest. This life cycle is remarkably similar to that of the Asian lycaenid Niphanda fusca, despite divergence 90 Mya. Comparable eco-evolutionary pathways resulted in a suite of ecomorphological homoplasies through the ontogeny. This study shows that convergent interactions can be more important than phylogenetic proximity in shaping functional traits of social parasites.

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