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Law CJ, Hlusko LJ, Tseng ZJ. Uncovering the mosaic evolution of the carnivoran skeletal system. Biol Lett 2024; 20:20230526. [PMID: 38263882 PMCID: PMC10806395 DOI: 10.1098/rsbl.2023.0526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 12/21/2023] [Indexed: 01/25/2024] Open
Abstract
The diversity of vertebrate skeletons is often attributed to adaptations to distinct ecological factors such as diet, locomotion, and sensory environment. Although the adaptive evolution of skull, appendicular skeleton, and vertebral column is well studied in vertebrates, comprehensive investigations of all skeletal components simultaneously are rarely performed. Consequently, we know little of how modes of evolution differ among skeletal components. Here, we tested if ecological and phylogenetic effects led to distinct modes of evolution among the cranial, appendicular and vertebral regions in extant carnivoran skeletons. Using multivariate evolutionary models, we found mosaic evolution in which only the mandible, hindlimb and posterior (i.e. last thoracic and lumbar) vertebrae showed evidence of adaptation towards ecological regimes whereas the remaining skeletal components reflect clade-specific evolutionary shifts. We hypothesize that the decoupled evolution of individual skeletal components may have led to the origination of distinct adaptive zones and morphologies among extant carnivoran families that reflect phylogenetic hierarchies. Overall, our work highlights the importance of examining multiple skeletal components simultaneously in ecomorphological analyses. Ongoing work integrating the fossil and palaeoenvironmental record will further clarify deep-time drivers that govern the carnivoran diversity we see today and reveal the complexity of evolutionary processes in multicomponent systems.
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Affiliation(s)
- Chris J. Law
- Department of Integrative Biology, University of Texas, Austin, TX, USA
- Burke Museum and Department of Biology, University of Washington, Seattle, WA, USA
- Department of Integrative Biology, University of California, Berkeley, CA, USA
| | - Leslea J. Hlusko
- National Research Center on Human Evolution (CENIEH), Burgos, Spain
| | - Z. Jack Tseng
- Department of Integrative Biology, University of California, Berkeley, CA, USA
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Rickman J, Burtner AE, Linden TJ, Santana SE, Law CJ. Size And Locomotor Ecology Have Differing Effects on the External and Internal Morphologies of Squirrel (Rodentia: Sciuridae) Limb Bones. Integr Org Biol 2023; 5:obad017. [PMID: 37361915 PMCID: PMC10286724 DOI: 10.1093/iob/obad017] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 04/19/2023] [Accepted: 05/10/2023] [Indexed: 06/28/2023] Open
Abstract
Mammals exhibit a diverse range of limb morphologies that are associated with different locomotor ecologies and structural mechanics. Much remains to be investigated, however, about the combined effects of locomotor modes and scaling on the external shape and structural properties of limb bones. Here, we used squirrels (Sciuridae) as a model clade to examine the effects of locomotor mode and scaling on the external shape and structure of the two major limb bones, the humerus and femur. We quantified humeral and femoral morphologies using 3D geometric morphometrics and bone structure analyses on a sample of 76 squirrel species across their four major ecotypes. We then used phylogenetic generalized linear models to test how locomotor ecology, size, and their interaction influenced morphological traits. We found that size and locomotor mode exhibit different relationships with the external shape and structure of the limb bones, and that these relationships differ between the humerus and femur. External shapes of the humerus and, to a lesser extent, the femur are best explained by locomotor ecology rather than by size, whereas structures of both bones are best explained by interactions between locomotor ecology and scaling. Interestingly, the statistical relationships between limb morphologies and ecotype were lost when accounting for phylogenetic relationships among species under Brownian motion. That assuming Brownian motion confounded these relationships is not surprising considering squirrel ecotypes are phylogenetically clustered; our results suggest that humeral and femoral variation partitioned early between clades and their ecomorphologies were maintained to the present. Overall, our results show how mechanical constraints, locomotor ecology, and evolutionary history may enact different pressures on the shape and structure of limb bones in mammals.
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Affiliation(s)
| | | | - T J Linden
- Department of Biology and Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98105, USA
| | - S E Santana
- Department of Biology and Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98105, USA
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Rodrigues AV, Grossel LA, Servino LM, Diniz-Filho JAF. Habitat Drives Body Size Evolution in Mustelidae (Mammalia: Carnivora). Evol Biol 2023. [DOI: 10.1007/s11692-023-09597-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Linden TJ, Burtner AE, Rickman J, McFeely A, Santana SE, Law CJ. Scaling patterns of body plans differ among squirrel ecotypes. PeerJ 2023; 11:e14800. [PMID: 36718452 PMCID: PMC9884040 DOI: 10.7717/peerj.14800] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 01/04/2023] [Indexed: 01/26/2023] Open
Abstract
Body size is often hypothesized to facilitate or constrain morphological diversity in the cranial, appendicular, and axial skeletons. However, how overall body shape scales with body size (i.e., body shape allometry) and whether these scaling patterns differ between ecological groups remains poorly investigated. Here, we test whether and how the relationships between body shape, body size, and limb lengths differ among species with different locomotor specializations, and describe the underlying morphological components that contribute to body shape evolution among squirrel (Sciuridae) ecotypes. We quantified the body size and shape of 87 squirrel species from osteological specimens held at museum collections. Using phylogenetic comparative methods, we first found that body shape and its underlying morphological components scale allometrically with body size, but these allometric patterns differ among squirrel ecotypes: chipmunks and gliding squirrels exhibited more elongate bodies with increasing body sizes whereas ground squirrels exhibited more robust bodies with increasing body size. Second, we found that only ground squirrels exhibit a relationship between forelimb length and body shape, where more elongate species exhibit relatively shorter forelimbs. Third, we found that the relative length of the ribs and elongation or shortening of the thoracic region contributes the most to body shape evolution across squirrels. Overall, our work contributes to the growing understanding of mammalian body shape evolution and how it is influenced by body size and locomotor ecology, in this case from robust subterranean to gracile gliding squirrels.
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Affiliation(s)
- Tate J. Linden
- University of Washington, Seattle, WA, United States of America
| | | | | | - Annika McFeely
- University of Washington, Seattle, WA, United States of America
| | | | - Chris J. Law
- University of Washington, Seattle, WA, United States of America,University of Texas at Austin, Austin, TX, United States of America,American Museum of Natural History, New York, NY, United States of America
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Law CJ, Blackwell EA, Curtis AA, Dickinson E, Hartstone-Rose A, Santana SE. Decoupled evolution of the cranium and mandible in carnivoran mammals. Evolution 2022; 76:2959-2974. [PMID: 35875871 DOI: 10.1111/evo.14578] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 06/06/2022] [Accepted: 06/17/2022] [Indexed: 01/22/2023]
Abstract
The relationship between skull morphology and diet is a prime example of adaptive evolution. In mammals, the skull consists of the cranium and the mandible. Although the mandible is expected to evolve more directly in response to dietary changes, dietary regimes may have less influence on the cranium because additional sensory and brain-protection functions may impose constraints on its morphological evolution. Here, we tested this hypothesis by comparing the evolutionary patterns of cranium and mandible shape and size across 100+ species of carnivoran mammals with distinct feeding ecologies. Our results show decoupled modes of evolution in cranial and mandibular shape; cranial shape follows clade-based evolutionary shifts, whereas mandibular shape evolution is linked to broad dietary regimes. These results are consistent with previous hypotheses regarding hierarchical morphological evolution in carnivorans and greater evolutionary lability of the mandible with respect to diet. Furthermore, in hypercarnivores, the evolution of both cranial and mandibular size is associated with relative prey size. This demonstrates that dietary diversity can be loosely structured by craniomandibular size within some guilds. Our results suggest that mammal skull morphological evolution is shaped by mechanisms beyond dietary adaptation alone.
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Affiliation(s)
- Chris J Law
- Department of Integrative Biology, University of Texas, Austin, Texas, 78712.,Department of Biology, University of Washington, Seattle, Washington, 98105.,Burke Museum of Natural History and Culture, University of Washington, Seattle, Washington, 98105.,Richard Gilder Graduate School, American Museum of Natural History, New York, New York, 10024.,Department of Mammalogy, American Museum of Natural History, New York, New York, 10024.,Division of Paleontology, American Museum of Natural History, New York, New York, 10024
| | - Emily A Blackwell
- Richard Gilder Graduate School, American Museum of Natural History, New York, New York, 10024.,Department of Mammalogy, American Museum of Natural History, New York, New York, 10024.,Division of Paleontology, American Museum of Natural History, New York, New York, 10024.,Department of Biological Sciences, Smith College, Northampton, Massachusetts, 01063
| | - Abigail A Curtis
- Department of Biology, University of Washington, Seattle, Washington, 98105.,Burke Museum of Natural History and Culture, University of Washington, Seattle, Washington, 98105
| | - Edwin Dickinson
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, 27695.,Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, New York, New York, 11545
| | - Adam Hartstone-Rose
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, 27695
| | - Sharlene E Santana
- Department of Biology, University of Washington, Seattle, Washington, 98105.,Burke Museum of Natural History and Culture, University of Washington, Seattle, Washington, 98105
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The impact of environmental factors on the evolution of brain size in carnivorans. Commun Biol 2022; 5:998. [PMID: 36130990 PMCID: PMC9492690 DOI: 10.1038/s42003-022-03748-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 07/20/2022] [Indexed: 11/28/2022] Open
Abstract
The reasons why some animals have developed larger brains has long been a subject of debate. Yet, it remains unclear which selective pressures may favour the encephalization and how it may act during evolution at different taxonomic scales. Here we studied the patterns and tempo of brain evolution within the order Carnivora and present large-scale comparative analysis of the effect of ecological, environmental, social, and physiological variables on relative brain size in a sample of 174 extant carnivoran species. We found a complex pattern of brain size change between carnivoran families with differences in both the rate and diversity of encephalization. Our findings suggest that during carnivorans’ evolution, a trade-off have occurred between the cognitive advantages of acquiring a relatively large brain allowing to adapt to specific environments, and the metabolic costs of the brain which may constitute a disadvantage when facing the need to colonize new environments. The brain size of carnivores has evolved to balance a trade-off between increased cognitive function and increased metabolic cost.
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Slater GJ. Topographically distinct adaptive landscapes for teeth, skeletons, and size explain the adaptive radiation of Carnivora (Mammalia). Evolution 2022; 76:2049-2066. [PMID: 35880607 PMCID: PMC9546082 DOI: 10.1111/evo.14577] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 06/08/2022] [Indexed: 01/22/2023]
Abstract
Models of adaptive radiation were originally developed to explain the early, rapid appearance of distinct modes of life within diversifying clades. Phylogenetic tests of this hypothesis have yielded limited support for temporally declining rates of phenotypic evolution across diverse clades, but the concept of an adaptive landscape that links form to fitness, while also crucial to these models, has received more limited attention. Using methods that assess the temporal accumulation of morphological variation and estimate the topography of the underlying adaptive landscape, I found evidence of an early partitioning of mandibulo-dental morphological variation in Carnivora (Mammalia) that occurs on an adaptive landscape with multiple peaks, consistent with classic ideas about adaptive radiation. Although strong support for this mode of adaptive radiation is present in traits related to diet, its signal is not present in body mass data or for traits related to locomotor behavior and substrate use. These findings suggest that adaptive radiations may occur along some axes of ecomorphological variation without leaving a signal in others and that their dynamics are more complex than simple univariate tests might suggest.
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Affiliation(s)
- Graham J. Slater
- Department of the Geophysical SciencesUniversity of ChicagoChicagoIllinois60637
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Law CJ. Different evolutionary pathways lead to incomplete convergence of elongate body shapes in carnivoran mammals. Syst Biol 2021; 71:788-796. [PMID: 34791502 DOI: 10.1093/sysbio/syab091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 11/01/2021] [Accepted: 11/09/2021] [Indexed: 11/13/2022] Open
Abstract
Although convergence is often recognized as a ubiquitous feature across the Tree of Life, whether the underlying traits also exhibit similar evolutionary pathways towards convergent forms puzzles biologists. In carnivoran mammals, "elongate," "slender," and "long" are often used to describe and even to categorize mustelids (martens, polecats, and weasels), herpestids (mongooses), viverrids (civets and genets), and other carnivorans together. But just how similar these carnivorans are and whether there is convergence in the morphological component that contribute to elongation has never been assessed. Here, I found that these qualitatively-described elongate carnivorans exhibited incomplete convergence towards elongate bodies compared to other terrestrial carnivorans. In contrast, the morphological components underlying body shape variation do not exhibit convergence despite evidence that these components are more elongate in elongate carnivorans compared to non-elongate carnivorans. Furthermore, these components also exhibited shorter but different phylogenetic half-lives towards more elongate adaptive peaks, indicating that different selective pressures can create multiple pathways to elongation. Incorporating the fossil record will facilitate further investigation of whether body elongation evolved adaptively or if it is simply a retained ancestral trait.
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Affiliation(s)
- Chris J Law
- Department of Biology, University of Washington, Seattle, WA, 98105; Richard Gilder Graduate School, Department of Mammalogy, and Division of Paleontology, American Museum of Natural History, New York, NY, USA 10024
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