1
|
Asymmetric Behavior in Ptyodactylus guttatus: Can a Digit Ratio Reflect Brain Laterality? Symmetry (Basel) 2020. [DOI: 10.3390/sym12091490] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The digit ratio, an indicator of brain laterality, is the ratio of the second and fourth digits on the left (L24) or right foot (R24). Much of the research on the digit ratio and brain laterality focuses on primates, rather than other species such as reptiles. We tested whether the digit ratio in the gecko Ptyodactylus guttatus was associated with behaviors attributed to brain laterality. We examined risk-taking behavior (time spent under cover), foot preference (which foot was the first to start moving) and the side from which geckos bypassed an obstacle, in relation to the digit ratio. Geckos with longer fourth digits on their left hind foot (higher digit ratio) spent more time under cover. Geckos starting to move with their left leg were much more likely to bypass obstacles from the right side, and vice versa. This is the first evidence of laterality being associated with the digit ratio in reptiles. Comparisons among vertebrates are needed in order to decipher the evolutionary origin of the commonalities and peculiarities of brain asymmetry and disentangle the patterns and drivers of our evolutionary tree.
Collapse
|
2
|
Seligmann H. First arrived, first served: competition between codons for codon-amino acid stereochemical interactions determined early genetic code assignments. Naturwissenschaften 2020; 107:20. [PMID: 32367155 DOI: 10.1007/s00114-020-01676-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 03/10/2020] [Accepted: 04/05/2020] [Indexed: 12/12/2022]
Abstract
Stereochemical nucleotide-amino acid interactions, in the form of noncovalent nucleotide-amino acid interactions, potentially produced the genetic code's codon-amino acid assignments. Empirical estimates of single nucleotide-amino acid affinities on surfaces and in solution are used to test whether trinucleotide-amino acid affinities determined genetic code assignments pending the principle "first arrived, first served": presumed early amino acids have greater codon-amino acid affinities than ulterior ones. Here, these single nucleotide affinities are used to approximate all 64 × 20 trinucleotide-amino acid affinities. Analyses show that (1) on surfaces, genetic code codon-amino acid assignments tend to match high affinities for the amino acids that integrated earliest the genetic code (according to Wong's metabolic coevolution hypothesis between nucleotides and amino acids) and (2) in solution, the same principle holds for the anticodon-amino acid assignments. Affinity analyses match best genetic code assignments when assuming that trinucleotides competed for amino acids, rather than amino acids for trinucleotides. Codon-amino acid affinities stick better to genetic code assignments than anticodon-amino acid affinities. Presumably, two independent coding systems, on surfaces and in solution, converged, and formed the current translation system. Proto-translation on surfaces by direct codon-amino acid interactions without tRNA-like adaptors coadapted with a system emerging in solution by proto-tRNA anticodon-amino acid interactions. These systems assigned identical or similar cognates to codons on surfaces and to anticodons in solution. Results indicate that a prebiotic metabolism predated genetic code self-organization.
Collapse
Affiliation(s)
- Hervé Seligmann
- The National Natural History Collections, The Hebrew University of Jerusalem, 91904, Jerusalem, Israel. .,Faculty of Medicine, Université Grenoble Alpes, Laboratory AGEIS EA 7407, Team Tools for e-Gnosis Medical & Labcom CNRS/UGA/OrangeLabs Telecoms4Health, F-38700, La Tronche, France.
| |
Collapse
|
3
|
Demongeot J, Seligmann H. Deamination gradients within codons after 1<->2 position swap predict amino acid hydrophobicity and parallel β-sheet conformational preference. Biosystems 2020; 191-192:104116. [PMID: 32081715 DOI: 10.1016/j.biosystems.2020.104116] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 12/04/2019] [Accepted: 02/10/2020] [Indexed: 12/16/2022]
Abstract
Deaminations C->T and A->G are frequent mutations producing nucleotide content gradients across genomes proportional to singlestrandedness during replication/transcription. Hence, within single codons, deamination risks increase from first to third codon positions, while second codon positions are functionally most crucial. Here genetic codes are analyzed assuming that after anticodons protected codons from deaminations, first and second codon positions swapped (N2N1N3->N1N2N3), with lowest deamination risks for N2 in presumed primitive N2N1N3 codons. N2N1N3, not standard N1N2N3, codon structure minimizes deaminations inversely proportionally to cognate amino acid hydrophobicity and parallel betasheet conformational preference. For N1N2N3, deamination minimization increases with genetic code integration order of cognate amino acids: during the presumed N2N1N3->N1N2N3 codon structure transition, protein synthesis combined direct codon-amino acid interactions for late amino acids and tRNA-based translation for early amino acids. Hence N2N1N3 codons would correspond to tRNA-free translation by spontaneous codon-amino acid affinities, and tRNA-mediated translation presumably caused N2N1N3->N1N2N3 swaps. Results show that rational, not arbitrary rules link codon and amino acid structures. Some analyses detect mitochondrial RNAs and peptides in public data corresponding to systematic position swaps, suggesting occasional swapping polymerase activity.
Collapse
Affiliation(s)
- Jacques Demongeot
- Université Grenoble Alpes, Faculty of Medicine, Laboratory AGEIS EA 7407, Team Tools for e-Gnosis Medical, F-38700, La Tronche, France.
| | - Hervé Seligmann
- Université Grenoble Alpes, Faculty of Medicine, Laboratory AGEIS EA 7407, Team Tools for e-Gnosis Medical, F-38700, La Tronche, France; The National Natural History Collections, The Hebrew University of Jerusalem, 91404, Jerusalem, Israel.
| |
Collapse
|
4
|
Seligmann H, Demongeot J. Codon Directional Asymmetry Suggests Swapped Prebiotic 1st and 2nd Codon Positions. Int J Mol Sci 2020; 21:E347. [PMID: 31948054 PMCID: PMC6981979 DOI: 10.3390/ijms21010347] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 01/03/2020] [Indexed: 01/23/2023] Open
Abstract
Background: Codon directional asymmetry (CDA) classifies the 64 codons into palindromes (XYX, CDA = 0), and 5'- and 3'-dominant (YXX and XXY, CDA < 0 and CDA > 0, respectively). Previously, CDA was defined by the purine/pyrimidine divide (A,G/C,T), where X is either a purine or a pyrimidine. For the remaining codons with undefined CDA, CDA was defined by the 5' or 3' nucleotide complementary to Y. This CDA correlates with cognate amino acid tRNA synthetase classes, antiparallel beta sheet conformation index and the evolutionary order defined by the self-referential genetic code evolution model (CDA < 0: class I, high beta sheet index, late genetic code inclusion). Methods: We explore associations of CDAs defined by nucleotide classifications according to complementarity strengths (A:T, weak; C:G, strong) and keto-enol/amino-imino groupings (G,T/A,C), also after swapping 1st and 2nd codon positions with amino acid physicochemical and structural properties. Results: Here, analyses show that for the eight codons whose purine/pyrimidine-based CDA requires using the rule of complementarity with the midposition, using weak interactions to define CDA instead of complementarity increases associations with tRNA synthetase classes, antiparallel beta sheet index and genetic code evolutionary order. CDA defined by keto-enol/amino-imino groups, 1st and 2nd codon positions swapped, correlates with amino acid parallel beta sheet formation indices and Doolittle's hydropathicities. Conclusions: Results suggest (a) prebiotic swaps from N2N1N3 to N1N2N3 codon structures, (b) that tRNA-mediated translation replaced direct codon-amino acid interactions, and (c) links between codon structures and cognate amino acid properties.
Collapse
Affiliation(s)
- Hervé Seligmann
- The National Natural History Collections, The Hebrew University of Jerusalem, 91404 Jerusalem, Israel
- Faculty of Medicine, Université Grenoble Alpes, Laboratory AGEIS EA 7407, Team Tools for e-Gnosis Medical, F-38700 La Tronche, France;
| | - Jacques Demongeot
- Faculty of Medicine, Université Grenoble Alpes, Laboratory AGEIS EA 7407, Team Tools for e-Gnosis Medical, F-38700 La Tronche, France;
| |
Collapse
|
5
|
Seligmann H. Protein Sequences Recapitulate Genetic Code Evolution. Comput Struct Biotechnol J 2018; 16:177-189. [PMID: 30002789 PMCID: PMC6040577 DOI: 10.1016/j.csbj.2018.05.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 05/14/2018] [Accepted: 05/17/2018] [Indexed: 12/16/2022] Open
Abstract
Several hypotheses predict ranks of amino acid assignments to genetic code's codons. Analyses here show that average positions of amino acid species in proteins correspond to assignment ranks, in particular as predicted by Juke's neutral mutation hypothesis for codon assignments. In all tested protein groups, including co- and post-translationally folding proteins, 'recent' amino acids are on average closer to gene 5' extremities than 'ancient' ones. Analyses of pairwise residue contact energies matrices suggest that early amino acids stereochemically selected late ones that stablilize residue interactions within protein cores, presumably producing 5'-late-to-3'-early amino acid protein sequence gradients. The gradient might reduce protein misfolding, also after mutations, extending principles of neutral mutations to protein folding. Presumably, in self-perpetuating and self-correcting systems like the genetic code, initial conditions produce similarities between evolution of the process (the genetic code) and 'ontogeny' of resulting structures (here proteins), producing apparent teleonomy between process and product.
Collapse
Affiliation(s)
- Hervé Seligmann
- Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes, UMR MEPHI, Aix-Marseille Université, IRD, Assistance Publique-Hôpitaux de Marseille, Institut Hospitalo-Universitaire Méditerranée-Infection, 19-21 boulevard Jean Moulin, 13005 Marseille, France.
| |
Collapse
|
6
|
Bijective codon transformations show genetic code symmetries centered on cytosine's coding properties. Theory Biosci 2017; 137:17-31. [PMID: 29147851 DOI: 10.1007/s12064-017-0258-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 11/13/2017] [Indexed: 12/11/2022]
Abstract
Homology of some RNAs with template DNA requires systematic exchanges between nucleotides. Such exchanges produce 'swinger' RNA along 23 bijective transformations (nine symmetric, X ↔ Y; and 14 asymmetric, X → Y → Z → X, for example A ↔ C and A → C → G → A, respectively). Here, analyses compare amino acids coded by swinger-transformed codons to those coded by untransformed codons, defining coding invariance after transformations. Swinger transformations cluster according to coding invariance in four groups characterized by transformations into cytosine (C = C, T → C, A → C, and G → C). C's central mutational coding role shows that swinger transformations constrained genetic code genesis. Coding invariance post-transformations correlate positively/negatively with mitochondrial swinger transcription/lepidosaurian body temperature. Presumably, low/high temperatures stabilize/revert rare swinger polymerization modes, producing long swinger sequences/point mutations, respectively. Coding invariance after swinger transformations might compensate effects of swinger polymerizations in species with low body temperatures. Hypothetically, swinger transcription increased coding potential of RNA self-replicating protolife systems under heating/cooling cycles.
Collapse
|
7
|
Seligmann H, Warthi G. Genetic Code Optimization for Cotranslational Protein Folding: Codon Directional Asymmetry Correlates with Antiparallel Betasheets, tRNA Synthetase Classes. Comput Struct Biotechnol J 2017; 15:412-424. [PMID: 28924459 PMCID: PMC5591391 DOI: 10.1016/j.csbj.2017.08.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 07/20/2017] [Accepted: 08/05/2017] [Indexed: 12/14/2022] Open
Abstract
A new codon property, codon directional asymmetry in nucleotide content (CDA), reveals a biologically meaningful genetic code dimension: palindromic codons (first and last nucleotides identical, codon structure XZX) are symmetric (CDA = 0), codons with structures ZXX/XXZ are 5'/3' asymmetric (CDA = - 1/1; CDA = - 0.5/0.5 if Z and X are both purines or both pyrimidines, assigning negative/positive (-/+) signs is an arbitrary convention). Negative/positive CDAs associate with (a) Fujimoto's tetrahedral codon stereo-table; (b) tRNA synthetase class I/II (aminoacylate the 2'/3' hydroxyl group of the tRNA's last ribose, respectively); and (c) high/low antiparallel (not parallel) betasheet conformation parameters. Preliminary results suggest CDA-whole organism associations (body temperature, developmental stability, lifespan). Presumably, CDA impacts spatial kinetics of codon-anticodon interactions, affecting cotranslational protein folding. Some synonymous codons have opposite CDA sign (alanine, leucine, serine, and valine), putatively explaining how synonymous mutations sometimes affect protein function. Correlations between CDA and tRNA synthetase classes are weaker than between CDA and antiparallel betasheet conformation parameters. This effect is stronger for mitochondrial genetic codes, and potentially drives mitochondrial codon-amino acid reassignments. CDA reveals information ruling nucleotide-protein relations embedded in reversed (not reverse-complement) sequences (5'-ZXX-3'/5'-XXZ-3').
Collapse
Affiliation(s)
- Hervé Seligmann
- Aix-Marseille Univ, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes, UM 63, CNRS UMR7278, IRD 198, INSERM U1095, Institut Hospitalo-Universitaire Méditerranée-Infection, Marseille, Postal code 13385, France
- Dept. Ecol Evol Behav, Alexander Silberman Inst Life Sci, The Hebrew University of Jerusalem, IL-91904 Jerusalem, Israel
| | - Ganesh Warthi
- Aix-Marseille Univ, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes, UM 63, CNRS UMR7278, IRD 198, INSERM U1095, Institut Hospitalo-Universitaire Méditerranée-Infection, Marseille, Postal code 13385, France
| |
Collapse
|
8
|
Breno M, Bots J, Van Dongen S. Heritabilities of directional asymmetry in the fore- and hindlimbs of rabbit fetuses. PLoS One 2013; 8:e76358. [PMID: 24130770 PMCID: PMC3794934 DOI: 10.1371/journal.pone.0076358] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 08/26/2013] [Indexed: 11/19/2022] Open
Abstract
Directional asymmetry (DA), where at the population level symmetry differs from zero, has been reported in a wide range of traits and taxa, even for traits in which symmetry is expected to be the target of selection such as limbs or wings. In invertebrates, DA has been suggested to be non-adaptive. In vertebrates, there has been a wealth of research linking morphological asymmetry to behavioural lateralisation. On the other hand, the prenatal expression of DA and evidences for quantitative genetic variation for asymmetry may suggest it is not solely induced by differences in mechanic loading between sides. We estimate quantitative genetic variation of fetal limb asymmetry in a large dataset of rabbits. Our results showed a low but highly significant level of DA that is partially under genetic control for all traits, with forelimbs displaying higher levels of asymmetry. Genetic correlations were positive within limbs, but negative across bones of fore and hind limbs. Environmental correlations were positive for all, but smaller across fore and hind limbs. We discuss our results in light of the existence and maintenance of DA in locomotory traits.
Collapse
Affiliation(s)
- Matteo Breno
- Evolutionary Biology Group, Department of Biology, University of Antwerp, Antwerp, Belgium
| | - Jessica Bots
- Evolutionary Biology Group, Department of Biology, University of Antwerp, Antwerp, Belgium
| | - Stefan Van Dongen
- Evolutionary Biology Group, Department of Biology, University of Antwerp, Antwerp, Belgium
| |
Collapse
|
9
|
|
10
|
Error compensation of tRNA misacylation by codon-anticodon mismatch prevents translational amino acid misinsertion. Comput Biol Chem 2011; 35:81-95. [PMID: 21470914 DOI: 10.1016/j.compbiolchem.2011.03.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Revised: 02/22/2011] [Accepted: 03/01/2011] [Indexed: 11/20/2022]
Abstract
Codon-anticodon mismatches and tRNA misloadings cause translational amino acid misinsertions, producing dysfunctional proteins. Here I explore the original hypothesis whether mismatches tend to compensate misacylation, so as to insert the amino acid coded by the codon. This error compensation is promoted by the fact that codon-anticodon mismatch stabilities increase with tRNA misacylation potentials (predicted by 'tfam') by non-cognate amino acids coded by the mismatched codons for most tRNAs examined. Error compensation is independent of preferential misacylation by non-cognate amino acids physico-chemically similar to cognate amino acids, a phenomenon that decreases misinsertion impacts. Error compensation correlates negatively with (a) codon/anticodon abundance (in human mitochondria and Escherichia coli); (b) developmental instability (estimated by fluctuating asymmetry in bilateral counts of subdigital lamellae, in each of two lizard genera, Anolis and Sceloporus); and (c) pathogenicity of human mitochondrial tRNA polymorphisms. Patterns described here suggest that tRNA misacylation is sometimes compensated by codon-anticodon mismatches. Hence translation inserts the amino acid coded by the mismatched codon, despite mismatch and misloading. Results suggest that this phenomenon is sufficiently important to affect whole organism phenotypes, as shown by correlations with pathologies and morphological estimates of developmental stability.
Collapse
|
11
|
Seligmann H. The ambush hypothesis at the whole-organism level: Off frame, ‘hidden’ stops in vertebrate mitochondrial genes increase developmental stability. Comput Biol Chem 2010; 34:80-5. [DOI: 10.1016/j.compbiolchem.2010.03.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Accepted: 03/02/2010] [Indexed: 01/24/2023]
|
12
|
Vervust B, Van Dongen S, Grbac I, Van Damme R. The mystery of the missing toes: extreme levels of natural mutilation in island lizard populations. Funct Ecol 2009. [DOI: 10.1111/j.1365-2435.2009.01580.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
13
|
Bateman PW, Fleming PA. To cut a long tail short: a review of lizard caudal autotomy studies carried out over the last 20 years. J Zool (1987) 2009. [DOI: 10.1111/j.1469-7998.2008.00484.x] [Citation(s) in RCA: 228] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
14
|
SELIGMANN HERVÉ, MORAVEC JIŘÍ, WERNER YEHUDAHL. Morphological, functional and evolutionary aspects of tail autotomy and regeneration in the ‘living fossil’Sphenodon (Reptilia: Rhynchocephalia). Biol J Linn Soc Lond 2008. [DOI: 10.1111/j.1095-8312.2008.00975.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
15
|
Directional asymmetry and correlation of tail injury with left-side dominance occur in Serpentes (Sauropsida). ZOOMORPHOLOGY 2007. [DOI: 10.1007/s00435-007-0028-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
16
|
Seligmann H, Krishnan NM. Mitochondrial replication origin stability and propensity of adjacent tRNA genes to form putative replication origins increase developmental stability in Lizards. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2006; 306:433-49. [PMID: 16463378 DOI: 10.1002/jez.b.21095] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Secondary structure stability of mitochondrial origins of light-strand replication (OL) presumably reduces delayed formation of light-strand initiating replication forks on the heavy strand. Delayed replication initiation prolongs single strandedness of the heavy strand. More mutations accumulate during the prolonged time spent single stranded. Presumably, delayed replication initiation and excess mutations affect mitochondrial biochemical processes and ultimately morphological outcomes of development at the whole-organism level. This predicts that developmental stability increases with OL secondary structure stability and with formation of OL-like structures by the five tRNA genes flanking recognized OLs. Stable OLs and high percentages of OL-resembling secondary structures of adjacent tRNA genes (predicted by Mfold) correlate positively with developmental stability in three lizard families (Anguidae, Amphisbaenidae, and Polychrotidae). Accounting for effects of the regular OL, Sfold-predicted OL-like propensity of the entire tRNA gene cluster (not of individual genes) correlates with increased developmental stability in Anguidae, also across the entire free-energy range of Boltzmann's distribution of secondary structures. In the fossorial Amphisbaenidae, the OL-like structure-forming propensity of tRNA genes correlates positively with developmental stability for the distribution's sub-optimally stable regions, and negatively for its optimally stable regions, suggesting the thermoregulated functioning of OL vs. flanking tRNA genes as replication origins. Results for polychrotid tRNA genes are intermediate. Anguid tRNA genes possibly function in addition to the regular OL. Mitochondrial tRNA genes may thus frequently acquire and lose the alternative OL function, without sequence (gene) duplication and loss of their primary function.
Collapse
Affiliation(s)
- Hervé Seligmann
- Department of Evolution, Systematics and Ecology, The Hebrew University of Jerusalem, 91404, Israel.
| | | |
Collapse
|
17
|
Werner YL, Seifan T. Eye size in geckos: Asymmetry, allometry, sexual dimorphism, and behavioral correlates. J Morphol 2006; 267:1486-500. [PMID: 17117406 DOI: 10.1002/jmor.10499] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The function of the vertebrate eye depends on its absolute size, and the size is presumably adapted to specific needs. We studied the variation of eye size at all levels, from intra-individual to inter-specific, in lid- less, spectacled, gecko lizards (Gekkonomorpha). We mea sured 1,408 museum specimens of 62 species, representing subfamilies Diplodactylinae, Gekkoninae, and Sphaerodactylinae. Intra-individually, eye size showed significant directional asymmetry in Stenodactylus sthenodactylus. A latitudinal study of six species confirmed that during postnatal ontogeny eye size undergoes conventional negative allometry; the slope is steeper among adults than among juveniles, expressing the need of juveniles for relatively larger eyes. Within species with sexual size dimorphism, commonly the larger sex possessed larger eyes in absolute terms but not relative to head-and-body length. Interspecifically, eye size showed negative allometry, with slope significantly steeper than those of intraspecific ontogenetic allometry, again expressing the need of juveniles for relatively larger eyes and showing that eye-size differences among species do not merely result from body-size differences. Finally, adult eye size varied interspecifically in correlation with parameters of behavioral ecology: eyes were significantly larger in nocturnal than in diurnal species, and significantly larger in cursorial than in scansorial species.
Collapse
Affiliation(s)
- Yehudah L Werner
- Department of Evolution, Systematics, and Ecology, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel.
| | | |
Collapse
|
18
|
Affiliation(s)
- Richard J Andrew
- Department of Biology and Environmental Science, School of Life Sciences, University of Sussex, Brighton, UK.
| |
Collapse
|
19
|
Werner YL, Safford SD, Seifan M, Saunders JC. Effects of age and size in the ears of gekkonomorph lizards: middle-ear morphology with evolutionary implications. ACTA ACUST UNITED AC 2005; 283:212-23. [PMID: 15685610 DOI: 10.1002/ar.a.20142] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The function of the ear depends in part on its absolute size and internal proportions. Thus, in both young individuals and small species, the middle ear is expected to be allometrically enlarged despite its smaller absolute size. Here we aim to compare the ontogenetic allometry of relevant middle-ear structures as observed within gecko (gekkonomorph lizards) species, with the evolutionary allometry observed interspecifically. These observations also provide middle-ear data for future evaluation of variation in auditory sensitivity. The material comprised 84 museum specimens of geckos, representing nine species of three gekkonomorph subfamilies. The results of dissections and measurements show that different reports notwithstanding, the middle-ear ossicular chain is indeed structured as described for geckos by Werner and Wever. Some sexual dimorphism is indicated, but this requires further study. During postnatal ontogeny, the allometric growth in the ratio of the columellar footplate area to body length differed between the intraspecific and interspecific levels, hence species differences in the middle ear do not merely result from animal size. The ratio of the tympanic membrane area to the columellar footplate area increased during ontogeny. In this, geckos resemble birds and probably also mammals. Similarly, when the comparison was among adults representing different species, the ratio of the tympanic membrane area to the columellar footplate area increased with body size. In this, however, the geckos differed from birds and mammals, in which this ratio varied taxonomically, irrespective of body size. It would thus seem that middle-ear proportions have evolved among geckos to produce small interspecific differences, but among amniote tetrapods they have evolved according to different principles in the classes reptiles, birds, and mammals.
Collapse
Affiliation(s)
- Yehudah L Werner
- Department of Otorhinolaryngology, Head and Neck Surgery, University of Pennsylvania, Philadelphia, PA, USA.
| | | | | | | |
Collapse
|