Vestigial structures in the appendicular skeletons of eight African skink species (Squamata, Scincidae)

Moch, John G.; Senter, Phil

doi:10.1111/j.1469-7998.2011.00839.x

Cited by 14 publications

(11 citation statements)

References 19 publications

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“…Three categories of skeletal structures were examined and considered candidates for identification as vestigial structures: (1) individual bones, (2) parts of individual bones (e.g., the shaft of the ulna), and (3) multiple-bone structures (e.g., the pelvic girdle, a limb, or a digit). Previous studies have identified vestigiality in all three anatomical categories ( Tague, 1997 ; Kearney, 2002 ; Bejder & Hall, 2002 ; Maxwell & Larsson, 2007 ; Senter, 2010 ; Bensimon-Brito et al, 2011 ; Moch & Senter, 2011 ).…”

Section: Methodsmentioning

confidence: 96%

“…We began by identifying examples of postcranial skeletal structures that were greatly reduced in comparison to their homologs in related taxa. To determine whether such structures could be considered vestigial we used the phylogenetic bracketing approach from a previous study ( Moch & Senter, 2011 ). According to this approach, a structure is considered vestigial if it satisfies the three criteria listed below, in comparison to its homolog in three successive sister taxa ( Table 2 ).…”

Section: Methodsmentioning

confidence: 99%

“…The term “vestigial” does not imply a complete lack of any function. Although some biologists maintain that it does (e.g., Prothero, 2007 ; Bergstrom & Dugatkin, 2012 ), most reject that strict view and follow Darwin (1859) in accepting that a vestigial structure has lost a salient function but may retain some other function (e.g., Bejder & Hall, 2002 ; Kearney, 2002 ; Hall, 2003 ; Simões-Lopes & Gutstein, 2004 ; Regoes et al, 2005 ; Espinasa & Jeffery, 2006 ; Franz-Odendaal & Hall, 2006 ; Prince & Johnson, 2006 ; Hall & Hallgrimsson, 2008 ; Zubidat, Nelson & Haim, 2010 ; Moch & Senter, 2011 ; Jackson & Auer, 2012 ). For example, the vestigial second and fourth metacarpals and metatarsals of horses no longer function as struts between a digit and the carpus or tarsus but still function as guides for suspensory ligaments and as muscle attachment sites, as well as supports for carpal and tarsal bones ( Smythe, 1967 ; Jackson & Auer, 2012 ).…”

Section: Introductionmentioning

confidence: 99%

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A critical survey of vestigial structures in the postcranial skeletons of extant mammals

Senter

Moch

2015

PeerJ

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In the Mammalia, vestigial skeletal structures abound but have not previously been the focus of study, with a few exceptions (e.g., whale pelves). Here we use a phylogenetic bracketing approach to identify vestigial structures in mammalian postcranial skeletons and present a descriptive survey of such structures in the Mammalia. We also correct previous misidentifications, including the previous misidentification of vestigial caviid metatarsals as sesamoids. We also examine the phylogenetic distribution of vestigiality and loss. This distribution indicates multiple vestigialization and loss events in mammalian skeletal structures, especially in the hand and foot, and reveals no correlation in such events between mammalian fore and hind limbs.

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Section: Methodsmentioning

confidence: 96%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A critical survey of vestigial structures in the postcranial skeletons of extant mammals

Senter

Moch

2015

PeerJ

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“…Amphiglossus ornaticeps presents well developed pectoral and pelvic girdles with complete pentadactyl and functional autopods, considered here as the typical plesiomorphic state expected in fully quadrupedal skinks [ 24 ], [ 48 ],[ 49 ]. In contrast, the examined limbless or bipedal species of the genera Grandidierina , Voeltzkowia and Paracontias show different degree of regression of girdles and autopods (Figs 3 and 4 ) (cf.…”

Section: Resultsmentioning

confidence: 99%

Distinct Patterns of Desynchronized Limb Regression in Malagasy Scincine Lizards (Squamata, Scincidae)

et al. 2015

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Scincine lizards in Madagascar form an endemic clade of about 60 species exhibiting a variety of ecomorphological adaptations. Several subclades have adapted to burrowing and convergently regressed their limbs and eyes, resulting in a variety of partial and completely limbless morphologies among extant taxa. However, patterns of limb regression in these taxa have not been studied in detail. Here we fill this gap in knowledge by providing a phylogenetic analysis of DNA sequences of three mitochondrial and four nuclear gene fragments in an extended sampling of Malagasy skinks, and microtomographic analyses of osteology of various burrowing taxa adapted to sand substrate. Based on our data we propose to (i) consider Sirenoscincus Sakata & Hikida, 2003, as junior synonym of Voeltzkowia Boettger, 1893; (ii) resurrect the genus name Grandidierina Mocquard, 1894, for four species previously included in Voeltzkowia; and (iii) consider Androngo Brygoo, 1982, as junior synonym of Pygomeles Grandidier, 1867. By supporting the clade consisting of the limbless Voeltzkowia mira and the forelimb-only taxa V. mobydick and V. yamagishii, our data indicate that full regression of limbs and eyes occurred in parallel twice in the genus Voeltzkowia (as hitherto defined) that we consider as a sand-swimming ecomorph: in the Voeltzkowia clade sensu stricto the regression first affected the hindlimbs and subsequently the forelimbs, whereas the Grandidierina clade first regressed the forelimbs and subsequently the hindlimbs following the pattern prevalent in squamates. Timetree reconstructions for the Malagasy Scincidae contain a substantial amount of uncertainty due to the absence of suitable primary fossil calibrations. However, our preliminary reconstructions suggest rapid limb regression in Malagasy scincids with an estimated maximal duration of 6 MYr for a complete regression in Paracontias, and 4 and 8 MYr respectively for complete regression of forelimbs in Grandidierina and hindlimbs in Voeltzkowia.

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“…Vestigial limbs or pelvic elements in otherwise legless tetrapods often show pronounced asymmetries. Either right or left may be present in legless skinks (Moch and Senter, 2011), whereas the right side is more likely reduced or absent in manatees (Shapiro et al, 2006).…”

Section: Tetrapodsmentioning

confidence: 99%

Developmental origins of normal and anomalous random right-left asymmetry: lateral inhibition versus developmental error in a threshold trait

Palmer

2012

CTOZ

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Dramatic examples of right-left asymmetry often inspire adaptive explanations, simply because it is hard to imagine how such forms could not be functionally significant. But are conspicuous morphological asymmetries necessarily adaptive? Surprisingly, in some species where direction of asymmetry is random, asymmetry in bilaterally paired traits may arise as a developmental error in a threshold trait. When cases of asymmetry are rare within a species, they are easily recognized as developmental errors. However, as asymmetrical individuals become more common, or if the asymmetry is in a signaling trait, the temptation to advance an adaptive explanation grows, particularly if the asymmetry is not clearly maladaptive. Several models of the ontogeny of asymmetry are described for both normal and anomalous random asymmetry of bilaterally paired traits. In the absence of selection, each model predicts different expected frequencies of symmetrical and asymmetrical individuals within a species, therefore such frequency distributions can effectively test for different models of development. In normal random asymmetries – where conspicuously asymmetrical individuals predominate – lateral inhibition of one side after the other has transformed appears to be an essential step in development. In anomalous random asymmetries – where conspicuously asymmetrical individuals are relatively rare – no lateral inhibition is required. Other potentially relevant variables include: purely stochastic variation in morphogen levels, useinduced asymmetry, and local (each side independent) versus central (e.g., hormonal) signaling. Examples of normal and anomalous random asymmetries are reviewed for several animal groups. A closer examination of the spectacular forelimb asymmetry in empidid dance flies raises doubts about claims that the asymmetry – both its occurrence and its direction – is adaptive, even though enlargement of the forelimbs likely is. Additional studies are required to conclude that this asymmetry is truly adaptive, as opposed to the outcome of random developmental variation in a threshold trait. This dance-fly leg asymmetry illustrates nicely how alternative hypotheses need to be considered before interpreting such variation as adaptive, even in a signaling trait.

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Vestigial structures in the appendicular skeletons of eight African skink species (Squamata, Scincidae)

Cited by 14 publications

References 19 publications

A critical survey of vestigial structures in the postcranial skeletons of extant mammals

A critical survey of vestigial structures in the postcranial skeletons of extant mammals

Distinct Patterns of Desynchronized Limb Regression in Malagasy Scincine Lizards (Squamata, Scincidae)

Developmental origins of normal and anomalous random right-left asymmetry: lateral inhibition versus developmental error in a threshold trait

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