Cranial sexual discrimination in hatchling broad-snouted caiman (Caiman latirostris)

Piña, Carlos Ignácio; Larriera, Alejandro; Siroski, Pablo Ariel; Verdade, Luciano Martins

doi:10.1590/s0073-47212007000100003

Cited by 14 publications

(13 citation statements)

References 21 publications

(25 reference statements)

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“…Verdade (2000) observed sexual dimorphism in the upper region of the cranium of juveniles and adults of C. latirostris, and Piña et al (2007) obtained similar results comparing newborns 24 hr after hatching. These authors suggested that this fact may be evolutionarily related to the visual recognition of sex when individuals exhibit only the top of their heads above the surface of the water.…”

Section: Discussionmentioning

confidence: 72%

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Genetic and morphometric variability in Caiman latirostris (broad‐snouted caiman), Reptilia, Alligatoridae

et al. 2009

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Caiman latirostris (broad-snouted caiman) is a crocodilian species from Argentina subject of management plans. The goal of this study was estimating the distribution of genetic variability using RAPD markers and quantitative traits in wild populations of C. latirostris from Santa Fe province, Argentina. We sampled animals from four populations to obtain DNA and morphometric measurements. Eight RAPD primers were used and PCR products were analyzed on 4% polyacrylamide gels stained with silver nitrate. Eleven allometric measurements were obtained in animals within 48 hr after birth. We were able to reveal a relatively high number of variable markers in the studied populations. Our estimates of polymorphism and heterozygosity are higher than recorded values in other crocodilians using isozymes, the studied populations showed low levels of gene flow and some population subdivision. The study of quantitative traits conducted by nested analysis of variance and principal component analysis indicated higher levels of variance among nests within populations than among populations. We found that some head measurements have the highest contribution to morphological differences among populations; this fact could support the role of these traits in reproductive or feeding behavior. Estimated genetic differentiation value (F(ST)) among populations was higher than quantitative trait differentiation value (Q(ST)), suggesting a higher contribution of neutral than adaptive loci to the genetic differentiation among populations. Quantitative traits are probably more related with fitness and the differentiation among populations remained relatively lower. The high heritability estimated for some traits indicates great potential to improve them in management plans.

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Section: Discussionmentioning

confidence: 72%

“…Sex can affect head morphometrics even in C. latirostris hatchlings, (Piña et al, 2007). Because of this, a considerable part of the variance found among clutches of the same population might be attributed to different sex ratio.…”

Section: Discussionmentioning

confidence: 99%

Genetic and morphometric variability in Caiman latirostris (broad‐snouted caiman), Reptilia, Alligatoridae

et al. 2009

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“…Recently, the black caiman ( M. niger ) was also shown to lack significant sexual dimorphism in allometric shape trajectories (Foth et al ., ). Yet, consistent sexual dimorphism has been reported in both hatchling (Piña et al ., ) and captive (Verdade, ) specimens of the broad‐snouted caiman ( Caiman latirostris ) based on linear distance measurements of the crania. In Ca.…”

Section: Discussionmentioning

confidence: 99%

The utility of cranial ontogeny for phylogenetic inference: a case study in crocodylians using geometric morphometrics

Watanabe

Slice

2014

J of Evolutionary Biology

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The degree to which the ontogeny of organisms could facilitate our understanding of phylogenetic relationships has long been a subject of contention in evolutionary biology. The famed notion that 'ontogeny recapitulates phylogeny' has been largely discredited, but there remains an expectation that closely related organisms undergo similar morphological transformations throughout ontogeny. To test this assumption, we used three-dimensional geometric morphometric methods to characterize the cranial morphology of 10 extant crocodylian species and construct allometric trajectories that model the post-natal ontogenetic shape changes. Using time-calibrated molecular and morphological trees, we employed a suite of comparative phylogenetic methods to assess the extent of phylogenetic signal in these trajectories. All analyses largely demonstrated a lack of significant phylogenetic signal, indicating that ontogenetic shape changes contain little phylogenetic information. Notably, some Mantel tests yielded marginally significant results when analysed with the morphological tree, which suggest that the underlying signal in these trajectories is correlated with similarities in the adult cranial morphology. However, despite these instances, all other analyses, including more powerful tests for phylogenetic signal, recovered statistical and visual evidence against the assumption that similarities in ontogenetic shape changes are commensurate with phylogenetic relatedness and thus bring into question the efficacy of using allometric trajectories for phylogenetic inference.

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“…ontogenetic variation, sexually dimorphic variation, polymorphisms) is crucial for accurate systematic, taxonomic, evolutionary, ecological, physiological and functional hypothesis of the different groups (Sudhaus and Rehfeld 1992;Wiesem€ uller et al 2003;Carpenter 2010;Porro et al 2011). Among extant crocodylians, previous studies of skull anatomy and intraspecific variation (including ontogenetic variation), evolution and functional morphology include those of Mook (1921), K€ alin (1933), Medem (1963), Iordansky (1973), Dodson (1975), Busbey (1989), Hall and Portier (1994), Monteiro and Soares (1997), Brochu (1999Brochu ( , 2001, Verdade (2000), Erickson et al (2003Erickson et al ( , 2012, McHenry et al (2006), Piña et al (2007), Wu et al (2006), Sadleir and Makovicky (2008), Platt et al (2009) and Bona and Desojo (2011). Nevertheless, lack of morphological studies and data, especially for osteology, is common to all extant South American crocodylians.…”

Section: Introductionmentioning

confidence: 99%

Intraspecific variation in the skull morphology of the black caiman Melanosuchus niger (Alligatoridae, Caimaninae)

2013

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Melanosuchus niger is a caimanine alligatorid widely distributed in the northern region of South America. This species has been the focus of several ecological, genetic and morphological studies. However, morphological studies have generally been limited to examination of interspecific variation among extant species of South American crocodylians. Here, we present the first study of intraspecific variation in the skull of M. niger using a two‐dimensional geometric morphometric approach. The crania of 52 sexed individuals varying in size were analysed to quantify shape variation and to assign observed shape changes to different types of intraspecific variation, that is, ontogenetic variation and sexual dimorphism. Most of the variation in this species is ontogenetic variation in snout length, skull depth, orbit size and the width of the postorbital region. These changes are correlated with bite force performance and probably dietary changes. However, a comparison with previous functional studies reveals that functional adaptations during ontogeny seem to be primarily restricted to the postrostral region, whereas rostral shape changes are more related to dietary shifts. Furthermore, the skulls of M. niger exhibit a sexual dimorphism, which is primarily size‐related. The presence of non‐size‐related sexual dimorphism has to be tested in future examinations.

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Cranial sexual discrimination in hatchling broad-snouted caiman (Caiman latirostris)

Cited by 14 publications

References 21 publications

Genetic and morphometric variability in Caiman latirostris (broad‐snouted caiman), Reptilia, Alligatoridae

Genetic and morphometric variability in Caiman latirostris (broad‐snouted caiman), Reptilia, Alligatoridae

The utility of cranial ontogeny for phylogenetic inference: a case study in crocodylians using geometric morphometrics

Intraspecific variation in the skull morphology of the black caiman Melanosuchus niger (Alligatoridae, Caimaninae)

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