1
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Di Martino E, Liow LH. Changing allometric relationships among fossil and Recent populations in two colonial species. Evolution 2022; 76:2424-2435. [PMID: 35993139 DOI: 10.1111/evo.14598] [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: 04/05/2022] [Revised: 08/01/2022] [Accepted: 08/05/2022] [Indexed: 01/22/2023]
Abstract
Allometry is vital for understanding the mechanisms underlying phenotypic evolution. Despite a large body of literature on allometry, studies based on fossil time series are limited for solitary organisms and nonexistent for colonial organisms. Allometric relationships have been found to be relatively constant across Recent populations of the same species, separated by space, but variable among fossil populations separated by thousands of years. How stable are allometric relationships at the module level for colonial organisms? We address this question using two extant species of the cheilostome bryozoan Microporella with fossil records spanning the Pleistocene of New Zealand. We investigate size covariation between feeding modules and three traits with separate functions (reproductive, resource uptake, and defense). We found that within-population (static) allometry can change on timescales of at least 0.1 million years. These within-population relationships do not consistently predict overintraspecific evolutionary allometry, which in turn does not predict those estimated at the genus level. Different functional traits are constrained to different extents by module size with defensive traits being the least constrained and most evolvable, compared with reproductive and resource uptake traits. Our study highlights the potential of colonial organisms in understanding the constraints and drivers of long-term phenotypic change.
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Affiliation(s)
| | - Lee Hsiang Liow
- Natural History Museum, University of Oslo, Oslo, 0562, Norway.,Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, Oslo, 0316, Norway
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2
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Larouche‐Bilodeau C, Guilbeault‐Mayers X, Cameron CB. Filter feeding, deviations from bilateral symmetry, developmental noise, and heterochrony of hemichordate and cephalochordate gills. Ecol Evol 2020; 10:13544-13554. [PMID: 33304558 PMCID: PMC7713955 DOI: 10.1002/ece3.6962] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 10/01/2020] [Accepted: 10/05/2020] [Indexed: 12/02/2022] Open
Abstract
We measured gill slit fluctuating asymmetry (FA), a measure of developmental noise, in adults of three invertebrate deuterostomes with different feeding modes: the cephalochordate Branchiostoma floridae (an obligate filter feeder), the enteropneusts Protoglossus graveolens (a facultative filter feeder/deposit feeder) and Saccoglossus bromophenolosus (a deposit feeder). FA was substantially and significantly low in B. floridae and P. graveolens and high in S. bromophenolosus. Our results suggest that the gills of species that have experienced a relaxation of the filter feeding trait exhibit elevated FA. We found that the timing of development of the secondary collagenous gill bars, compared to the primary gill bars, was highly variable in P. graveolens but not the other two species, demonstrating an independence of gill FA from gill bar heterochrony. We also discovered the occasional ectopic expression of a second set of paired gills posterior to the first set of gills in the enteropneusts and that these were more common in S. bromophenolosus. Moreover, our finding that gill slits in enteropneusts exhibit bilateral symmetry suggests that the left-sidedness of larval cephalochordate gills, and the directional asymmetry of Cambrian stylophoran echinoderm fossil gills, evolved independently from a bilaterally symmetrical ancestor.
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3
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Tague RG. Rudimentary, "functionless" first metapodials of Canis latrans: Variation and association in length with longer, functional metapodials. Evolution 2020; 74:2465-2482. [PMID: 32969028 DOI: 10.1111/evo.14100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 08/20/2020] [Accepted: 09/13/2020] [Indexed: 11/30/2022]
Abstract
A tenet of evolutionary theory is that phenotypic variation of a trait is inversely related to the intensity of stabilizing selection pressure. Among homologous bones, such as metapodials, a rudimentary, "nonfunctional" bone is expected to be more variable in length than nonrudimentary bones. This study compares variation and association in length among metapodials using 277 adult skeletons of Canis latrans. Canis latrans has a short, "functionless" first metacarpal (mc1) and "rudimentary, vestigial" first metatarsal (mt1). Results show that among the 10 metapodials, mt1 has the highest variation in length; other metapodials do not differ significantly from one another in their variation. Correlation coefficients for length of mc1 and mt1 with their ipsilateral metapodials 2-5 are significantly lower than coefficients for all other ipsilateral pairs. The correlation coefficient between left and right mt1 is significantly the lowest among all bilateral pairs of metapodials. Results are interpreted as follows. Mt1's high variation and low association in length are the outcome of less intense stabilizing selection pressure compared with other metapodials. The nonsignificant difference for variation in length between mc1 and metapodials 2-5 may be that mc1 is functional for development of a pollical dewclaw that helps restrain small prey.
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Affiliation(s)
- Robert G Tague
- Department of Geography and Anthropology, Louisiana State University, Baton Rouge, LA, 70803
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4
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Schottenstein NH, Hubbe M, Hunter J. Modules and Mosaics in the Evolution of the Tetonius – Pseudotetonius Dentition. J MAMM EVOL 2019. [DOI: 10.1007/s10914-019-09488-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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5
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Vitek NS, Manz CL, Gao T, Bloch JI, Strait SG, Boyer DM. Semi-supervised determination of pseudocryptic morphotypes using observer-free characterizations of anatomical alignment and shape. Ecol Evol 2017; 7:5041-5055. [PMID: 28770045 PMCID: PMC5528226 DOI: 10.1002/ece3.3058] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 03/26/2017] [Accepted: 04/25/2017] [Indexed: 11/29/2022] Open
Abstract
Accurate, quantitative characterization of complex shapes is recognized as a key methodological challenge in biology. Recent development of automated three‐dimensional geometric morphometric protocols (auto3dgm) provides a promising set of tools to help address this challenge. While auto3dgm has been shown to be useful in characterizing variation across clades of morphologically very distinct mammals, it has not been adequately tested in more problematic cases where pseudolandmark placement error potentially confounds interpretation of true shape variation. Here, we tested the sensitivity of auto3dgm to the degree of variation and various parameterization settings using a simulation and three microCT datasets that characterize mammal tooth crown morphology as biological examples. The microCT datasets vary in degree of apparent morphological differentiation, with two that include grossly similar morphospecies and one that includes two laboratory strains of a single species. Resulting alignments are highly sensitive to the number of pseudolandmarks used to quantify shapes. The degree to which the surfaces were downsampled and the apparent degree of morphological differentiation across the dataset also influenced alignment repeatability. We show that previous critiques of auto3dgm were based on poorly parameterized alignments and suggest that sample‐specific sensitivity analyses should be added to any research protocol including auto3dgm. Auto3dgm is a useful tool for studying samples when pseudolandmark placement error is small relative to the true differences between specimens. This method therefore represents a promising avenue forward in morphometric studies at a wide range of scales, from samples that differ by a single genetic locus to samples that represent multiple phylogenetically diverse clades.
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Affiliation(s)
- Natasha S Vitek
- Florida Museum of Natural History University of Florida Gainesville FL USA.,Department of Biology University of Florida Gainesville FL USA
| | - Carly L Manz
- Florida Museum of Natural History University of Florida Gainesville FL USA.,Department of Genetics, Development, and Cell Biology Iowa State University Ames IA USA
| | - Tingran Gao
- Department of Mathematics Duke University Durham NC USA
| | - Jonathan I Bloch
- Florida Museum of Natural History University of Florida Gainesville FL USA
| | - Suzanne G Strait
- Department of Biological Sciences Marshall University Huntington WV USA
| | - Doug M Boyer
- Department of Evolutionary Anthropology Duke University Durham NC USA
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6
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Tague RG. VARIABILITY OF A VESTIGIAL STRUCTURE: FIRST METACARPAL INCOLOBUS GUEREZAANDATELES GEOFFROYI. Evolution 2017; 51:595-605. [DOI: 10.1111/j.1558-5646.1997.tb02446.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/1995] [Accepted: 11/20/1996] [Indexed: 11/29/2022]
Affiliation(s)
- Robert G. Tague
- Department of Geography and Anthropology; Louisiana State University; Baton Rouge Louisiana 70803-4105
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7
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Lande R. NATURAL SELECTION AND RANDOM GENETIC DRIFT IN PHENOTYPIC EVOLUTION. Evolution 2017; 30:314-334. [PMID: 28563044 DOI: 10.1111/j.1558-5646.1976.tb00911.x] [Citation(s) in RCA: 821] [Impact Index Per Article: 117.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/1975] [Revised: 11/12/1975] [Indexed: 11/27/2022]
Affiliation(s)
- Russell Lande
- Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts, 02138
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8
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Farris JS. ESTIMATION OF CONSERVATISM OF CHARACTERS BY CONSTANCY WITHIN BIOLOGICAL POPULATIONS. Evolution 2017; 20:587-591. [PMID: 28562907 DOI: 10.1111/j.1558-5646.1966.tb03389.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/30/1966] [Indexed: 11/30/2022]
Affiliation(s)
- James S Farris
- Museum of Zoology, The University of Michigan, Ann Arbor
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9
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Markova EA, Smirnov NG, Kourova TP, Kropacheva YE. Ontogenetic variation in occlusal shape of evergrowing molars in voles: An intravital study in Microtus gregalis (Arvicolinae, Rodentia). Mamm Biol 2013. [DOI: 10.1016/j.mambio.2013.03.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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10
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Labonne G, Laffont R, Renvoise E, Jebrane A, Labruere C, Chateau‐Smith C, Navarro N, Montuire S. When less means more: evolutionary and developmental hypotheses in rodent molars. J Evol Biol 2012; 25:2102-2111. [DOI: 10.1111/j.1420-9101.2012.02587.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Revised: 07/04/2012] [Accepted: 07/04/2012] [Indexed: 11/28/2022]
Affiliation(s)
- G. Labonne
- Laboratoire Paléobiodiversité et Evolution de l'EPHE Université de Bourgogne Dijon France
- UMR CNRS 6282 Biogéosciences Université de Bourgogne Dijon France
| | - R. Laffont
- UMR CNRS 6282 Biogéosciences Université de Bourgogne Dijon France
| | - E. Renvoise
- Institute of Biotechnology University of Helsinki Helsinki Finland
| | - A. Jebrane
- Institut mathématique de Bourgogne UMR CNRS 5584 Dijon France
| | - C. Labruere
- Institut mathématique de Bourgogne UMR CNRS 5584 Dijon France
| | | | - N. Navarro
- Laboratoire Paléobiodiversité et Evolution de l'EPHE Université de Bourgogne Dijon France
- UMR CNRS 6282 Biogéosciences Université de Bourgogne Dijon France
| | - S. Montuire
- Laboratoire Paléobiodiversité et Evolution de l'EPHE Université de Bourgogne Dijon France
- UMR CNRS 6282 Biogéosciences Université de Bourgogne Dijon France
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11
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Mckitrick MC. Individual variation in the flexor cruris lateralis muscle of the Tyrannidae (Aves: Passeriformes) and its possible significance. J Zool (1987) 2011. [DOI: 10.1111/j.1469-7998.1986.tb03580.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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12
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Reig OA. A proposed unified nomenclature for the enamelled components of the molar teeth of the Cricetidae (Rodentia). J Zool (1987) 2009. [DOI: 10.1111/j.1469-7998.1977.tb03238.x] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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13
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Pietsch VM. Biometrische Analyse an Schädeln von neun Kleinsäuger-Arten aus der Familie Arvicolidae (Rodentia). J ZOOL SYST EVOL RES 2009. [DOI: 10.1111/j.1439-0469.1980.tb00739.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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14
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Pinhasi R, Eshed V, Shaw P. Evolutionary changes in the masticatory complex following the transition to farming in the southern Levant. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2008; 135:136-48. [DOI: 10.1002/ajpa.20715] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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15
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Kavanagh KD, Evans AR, Jernvall J. Predicting evolutionary patterns of mammalian teeth from development. Nature 2007; 449:427-32. [PMID: 17898761 DOI: 10.1038/nature06153] [Citation(s) in RCA: 267] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2007] [Accepted: 08/07/2007] [Indexed: 11/08/2022]
Abstract
One motivation in the study of development is the discovery of mechanisms that may guide evolutionary change. Here we report how development governs relative size and number of cheek teeth, or molars, in the mouse. We constructed an inhibitory cascade model by experimentally uncovering the activator-inhibitor logic of sequential tooth development. The inhibitory cascade acts as a ratchet that determines molar size differences along the jaw, one effect being that the second molar always makes up one-third of total molar area. By using a macroevolutionary test, we demonstrate the success of the model in predicting dentition patterns found among murine rodent species with various diets, thereby providing an example of ecologically driven evolution along a developmentally favoured trajectory. In general, our work demonstrates how to construct and test developmental rules with evolutionary predictability in natural systems.
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Affiliation(s)
- Kathryn D Kavanagh
- Evolution & Development Unit, Institute of Biotechnology, PO Box 56 (Viikinkaari 9), FIN-00014 University of Helsinki, Finland.
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16
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Guthrie RD. Rapid body size decline in Alaskan Pleistocene horses before extinction. Nature 2003; 426:169-71. [PMID: 14614503 DOI: 10.1038/nature02098] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2003] [Accepted: 09/23/2003] [Indexed: 11/08/2022]
Abstract
About 70% of North American large mammal species were lost at the end of the Pleistocene epoch. The causes of this extinction--the role of humans versus that of climate--have been the focus of much controversy. Horses have figured centrally in that debate, because equid species dominated North American late Pleistocene faunas in terms of abundance, geographical distribution, and species variety, yet none survived into the Holocene epoch. The timing of these equid regional extinctions and accompanying evolutionary changes are poorly known. In an attempt to document better the decline and demise of two Alaskan Pleistocene equids, I selected a large number of fossils from the latest Pleistocene for radiocarbon dating. Here I show that horses underwent a rapid decline in body size before extinction, and I propose that the size decline and subsequent regional extinction at 12,500 radiocarbon years before present are best attributed to a coincident climatic/vegetational shift. The present data do not support human overkill and several other proposed extinction causes, and also show that large mammal species responded somewhat individualistically to climate changes at the end of the Pleistocene.
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Affiliation(s)
- R Dale Guthrie
- Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska 99775, USA.
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17
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Tague RG. Variability of metapodials in primates with rudimentary digits: Ateles geoffroyi, Colobus guereza, and Perodicticus potto. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2002; 117:195-208. [PMID: 11842399 DOI: 10.1002/ajpa.10028] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A tenet of evolutionary theory is that, within a species, phenotypic variability is inversely related to the intensity of stabilizing selection. A corollary is that a rudimentary or vestigial structure should be highly variable. This relationship between rudimentation and variability, however, may simply be part of a continuum, as several studies have shown that variability and size of a structure are inversely related. This study tests whether the first metacarpal (MC1) in Ateles geoffroyi and Colobus guereza and the second metacarpal (MC2) in Perodicticus potto are highly variable in their lengths relative to their other metapodials. The former two species have rudimentary thumbs, and the latter species has a rudimentary index finger. Fourteen other species of primates are included in the comparison. The results show that MC1 in A. geoffroyi and C. guereza and MC2 in P. potto are the relatively shortest first and second metapodials, respectively, in this sample of primates. However, an intraspecific analysis shows that neither MC1 in A. geoffroyi and C. guereza nor MC2 in P. potto is significantly more variable than the other metapodials. Nevertheless, an interspecific analysis shows that MC1 in A. geoffroyi and C. guereza is relatively the most variable among the first metapodials (i.e., MC1 and first metatarsal) in this study. MC2 in P. potto, however, is of relatively low variability compared with the other primates. These contrasting results are interpreted in terms of the developmental and evolutionary biology of digits.
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Affiliation(s)
- Robert G Tague
- Department of Geography and Anthropology, Louisiana State University, Baton Rouge, Louisiana 70803-4105, USA.
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18
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Polly PD. Development and evolution occlude: evolution of development in mammalian teeth. Proc Natl Acad Sci U S A 2000; 97:14019-21. [PMID: 11121009 PMCID: PMC34086 DOI: 10.1073/pnas.97.26.14019] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- P D Polly
- Molecular and Cellular Biology Section, Division of Biomedical Sciences, Queen Mary & Westfield College, London E1 4NS, United Kingdom.
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19
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Tague RG. Variation in pelvic size between males and females in nonhuman anthropoids. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 1995; 97:213-33. [PMID: 7573375 DOI: 10.1002/ajpa.1330970302] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Whether there is a sexual difference in phenotypic variance has been the subject of theoretical and empirical studies. The presence of such a difference is integral to some models on the evolution of sexual dimorphism. Several studies report that males are more variable than females for nonpelvic measures. This study tests for a sexual difference in variability of the pelvis. Phenotypic variance is a correlate of both the intensity and mode of selection. In both sexes, the pelvis is subject primarily to stabilizing selection. However, selection intensity is greater among females than among males because only among females does the pelvis function as a birth canal and, thereby, serve as a proximate cause of death. As selection intensity and phenotypic variability are inversely related under stabilizing selection, the implication is that females should be less variable than males in pelvic size and shape. However, the results of previous studies on this issue are equivocal or contradictory. This study compares the sexes for differences in pelvic variability by analyzing nine species (and ten samples) of nonhuman anthropoids. Data were collected on 16 measures of the pelvis; only adults were used. Levene's univariate and multivariate tests for relative variation were used in the analysis. The results show that the sexes do not differ significantly in pelvic variability either within or among the nine samples of noncaptive anthropoids. Only in the one sample of captive specimens (Saimiri sciureus) do the sexes differ significantly in pelvic variability, with males being more variable than females. Two interpretations are derived from these results. First, the sexual difference in variability in captive Saimiri may be due either to a bias in the selection of Saimiri specimens by the captors/experimentors or to a sexual difference in growth associated with the stress of captivity. Second, the sexes do not differ in pelvic variability among noncaptive anthropoids because the anlage of the pelvis is bipotential in development. The intrinsic (i.e., agonadal) pattern of growth and development is that characteristic of a female. Testicular androgens are requisite to redirect the pattern of growth and development to that characteristic of a male. However, the redirected pattern of growth in males simply shifts en masse the intrinsic (i.e., female) distribution curve. The consequence among adults is sexual dimorphism in pelvic size, but sexual equivalency in relative pelvic variability.
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Affiliation(s)
- R G Tague
- Department of Geography and Anthropology, Louisiana State University, Baton Rouge 70803-4105
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20
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Kesner MH. Functional morphology of the masticatory musculature of the rodent subfamily microtinae. J Morphol 1980; 165:205-22. [PMID: 7005453 DOI: 10.1002/jmor.1051650208] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Voles and lemmings are the most successful group of graminivorous rodents, but the adaptations allowing them to enter this niche are not fully known. Dissections of the masticatory musculature of the 12 genera and subgenera of North American microtines show an increase in the potential anterior vector component and in the potential vertical vector component of these muscles relative to the molar tooth row. The result is a separation of the compressive and propulsive functions of the masticatory muscles during the power stroke of mastication. This has led to the formulation of a propalinal "swing" hypothesis which is supported by vector analyses of the musculature.
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21
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Oxberry BA. An anatomical, histochemical, and autoradiographic study of the ever-growing molar dentition of Microtus with comments on the role of structure in growth and eruption. J Morphol 1975; 147:337-53. [PMID: 1102718 DOI: 10.1002/jmor.1051470307] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
An analysis of the microanatomy of the molar dentition of Microtus utilizing histological, histochemical and autoradiographic techniques reveals a complex architecture with distinctive morphogenic mechanisms which respond to the functional requirements of the organism. These mechanisms include; the maintenance of continued growth and eruption of the molars to compensate for continued hard tissue loss from wear at the occlusal surface of the crown throughout the entire lifespan of the orgainism and a positive feedback repair mechanism to protect the growth systems from the potential destruction this normal occlusal wear could initiate. An awareness and understanding of these phenomena is of significant value for interpreting palentological specimens and formulating a theoretical model for interpreting the evolution of Microtine molar dentitions.
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22
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Corruccini RS. The biological relationships of some prehistoric and historic Pueblo populations. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 1972; 37:373-88. [PMID: 5082931 DOI: 10.1002/ajpa.1330370307] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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23
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Abstract
Variability of bill length was compared between populations of species present on the Tres Marías Islands and appropriate nearby mainland. Four species were significantly less variable on the islands, one species was significantly more variable, and 11 species were not significantly different in the two regions. Explanations are offered in terms of available food supply: availability may be influenced by competitors. Data from other islands are consistent with this interpretation. However, no clear trend towards greater or less variability on islands has so far been revealed.
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