ORCID Profile
0000-0001-7484-7026
Current Organisation
University of Kentucky
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Publisher: Bentham Science Publishers Ltd.
Date: 05-2021
DOI: 10.2174/1567205018666210823100721
Abstract: There is strong evidence that epigenetic age acceleration is associated with increased risk of later-life diseases and all-cause mortality. However, there is currently limited evidence that suggests accelerated epigenetic age is associated with dementia risk. This study aims to clarify whether epigenetic biomarkers of accelerated aging can predict dementia risk, which is an important consideration as aging is the greatest risk factor for the disease. DNA methylation was measured in peripheral blood s les provided by 160 participants from the ASPirin in Reducing Events in the Elderly study, including 73 pre-symptomatic dementia cases and 87 controls matched for age, sex, and smoking and education status. Epigenetic age was calculated using Horvath, Hannum, GrimAge and PhenoAge DNA methylation clocks, and age acceleration (the disparity between chronological age and epigenetic age) was determined. There was no difference in age acceleration between dementia cases and controls. In males, only Hannum’s intrinsic epigenetic age acceleration was increased in pre-symptomatic dementia cases compared to controls (Δ +1.8 years, p = 0.03). These findings provide no strong evidence that accelerated epigenetic aging measured in peripheral blood can predict dementia risk.
Publisher: Herpetologists League
Date: 09-2011
Publisher: Instituto de Ecologia, A.C.
Date: 16-11-2018
DOI: 10.21829/AZM.2018.3412140
Abstract: Se presentan nuevos registros de Sincella incerta en el estado de Chiapas y se confirma su presencia en la región central del estado. Uno de los registros de las estribaciones costeras del sureste llena un espacio en la distribución de la especie entre registros anteriores de Chiapas y Guatemala.
Publisher: Wiley
Date: 17-05-2018
DOI: 10.1111/JBI.13241
Publisher: Springer Science and Business Media LLC
Date: 12-02-2022
DOI: 10.1186/S12862-022-01970-6
Abstract: Heterochrony, change in the rate or timing of development, is thought to be one of the main drivers of morphological evolution, and allometry, trait scaling patterns imposed by size, is traditionally thought to represent an evolutionary constraint. However, recent studies suggest that the ontogenetic allometric trajectories describing how organisms change as they grow may be labile and adaptive. Here we investigated the role of postnatal ontogenetic development in the morphological ersification of Paleoanguimorpha, the monitor lizards and allies, a clade with extreme body size disparity. We obtained linear and geometric morphometric data for more than 1,600 specimens belonging to three families and 60 species, representing ~ 72% of extant paleoanguimorph ersity. We used these data to undertake one of the largest comparative studies of ontogenetic allometry to date. Heterochrony is likely dictating morphological ergence at shallow evolutionary scales, while changes in the magnitude and direction of ontogenetic change are found mainly between major clades. Some patterns of ontogenetic variation and morphological disparity appear to reflect ontogenetic transitions in habitat use. Generally, juveniles are more similar to each other than adults, possibly because species that differ in ecology as adults are arboreal as juveniles. The magnitude of ontogenetic change follows evolutionary models where variation is constrained around an optimal value. Conversely, the direction of ontogenetic change may follow models with different adaptive optima per habitat use category or models where interspecific interactions influence its evolution. Finally, we found that the evolutionary rates of the ontogenetic allometric trajectories are phylogenetically variable. The attributes of ontogenetic allometric trajectories and their evolutionary rates are phylogenetically heterogeneous in Paleoanguimorpha. Both allometric constraints and ecological factors have shaped ontogeny in the group. Our study highlights the evolutionary lability and adaptability of postnatal ontogeny, and teases apart how different evolutionary shifts in ontogeny contribute to the generation of morphological ersity at different evolutionary scales.
Publisher: Pensoft Publishers
Date: 06-09-2019
DOI: 10.15560/15.5.729
Abstract: Rhadinaea marcellae Taylor, 1949 is known from only 12 specimens. Based on recent fieldwork and research in scientific collections and databases, we report 14 new records of R. marcellae , bringing the total number of verified occurrences up to 26, updating our understanding of this secretive species’ distribution in the tropical and cloud forests of the Sierra Madre Oriental in Mexico. The new records come from the Mexican states of Hidalgo, Puebla, San Luis Potosí and Veracruz. All the newly reported specimens are morphologically concordant with R. marcellae , but exhibit noteworthy variation.
Publisher: Elsevier BV
Date: 10-2019
DOI: 10.1016/J.YMPEV.2019.106524
Abstract: Organisms rapidly ersifying across unstable environments such as mountain tops provide substantial challenges for resolving evolutionary histories and delimiting species. The Liolaemus leopardinus clade is a group of five species of lizards adapted to high altitudes in central Chile, with most species found in the Andes, but one species, L. frassinettii is found in the independent Costa Cordillera. Despite their allopatric distributions, they display shallow mitochondrial ergences, making phylogenetics and species delimitation of this clade hard to resolve. We use an integrative approach to delimit species by considering morphological data (linear and landmark-based), mitochondrial DNA (mtDNA), and nuclear DNA (Sequences and SNPs collected with ddRADseq). We find strong conflicting signals between phylogenetic analyses of the nuclear and mtDNA data. While mtDNA places L. frassinettii as sister to the rest of the clade, the SNPs support a south to north order of ergences, with southernmost species (new taxon described here) as sister to the rest of the clade. Moreover, species delimitation using mtDNA only supports two species (one in the Costa and one in the Andes), whereas combined analyses using the nuclear data and morphology support multiple Andean taxa, including a new one we describe here. Based on these results, population structure analyses and our knowledge of the geological and climatic history of the Andes, we argue that this mito-nuclear discordance is explained by past introgression among the Andean taxa, likely during glacial periods that forced these lizards to lower altitudes where they would hybridize. The complete isolation between the Costa and Andes cordilleras has prevented any further contact between taxa on either mountain chain. Our study highlights the importance of using multiple lines of evidence to resolve evolutionary histories, and the potential misleading results from relying solely on mtDNA.
Publisher: Pensoft Publishers
Date: 08-08-2018
DOI: 10.3897/ZOOKEYS.780.25593
Abstract: A new species of the Rhadinaeadecorata group is described based on two specimens from the Sierra Madre del Sur, Guerrero, Mexico. The new species differs from all other members of the genus Rhadinaea by having: eight supralabials 149–151 (male) ventrals 63–77 (male) subcaudals two large pale nuchal blotches, forming an incomplete collar that occupies two scales laterally and is bissected along the dorsal midline a postocular pale marking consisting of a well-defined, narrow line beginning behind the upper posterior margin of the eye and extending posteriorly nearly horizontally until connecting with the nuchal blotches and the dark ground color of the flanks extending to the lateral portion of the ventrals. The large nuchal blotches distinguish the new species from the other members of the R.decorata group, except for R.cuneata and some in iduals of R.hesperia (pale nuchal marking one-scale wide in R.marcellae , absent in the other species). The condition of the postocular pale marking distinguishes it from R.cuneata and R.hesperia (postocular pale marking wedge-shaped in R.cuneata , not connected with the pale post-cephalic markings in R.hesperia ). Furthermore, the number of subcaudals and the coloration of the lateral portion of the ventrals distinguish it from R.omiltemana and R.taeniata , the remaining congeners found in Guerrero (85–90 in males of R.omiltemana and 91–121 in R.taeniata dark color of the flanks not reaching ventrals in the former species, occasionally and faintly in R.taeniata ). Additionally, a new combination for R.stadelmani is proposed. The new species is the first described in the genus Rhadinaea in more than 40 years.
Publisher: Elsevier BV
Date: 08-2022
DOI: 10.1016/J.YMPEV.2022.107516
Abstract: Genomic data are a powerful tool for the elucidation of evolutionary patterns at the population level and above. The combined analysis of genomic and morphological data can result in species delimitation hypotheses that reflect evolutionary history better than traditional taxonomy or any in idual source of evidence. Here, we used thousands of single nucleotide polymorphisms, mitochondrial sequences, and comprehensive morphological data to characterize the evolutionary history of the ridge-tailed monitors in the Varanus acanthurus complex (V. acanthurus, V. baritji, and V. storri), a group of saxicolous lizards with a wide distribution in Australia, the driest vegetated continent. We found substantial genetic structure in the group and identify nine geographically clustered populations. Based on admixture patterns and species delimitation analyses we propose a taxonomic scheme that differs from current taxonomy. We consider V. acanthurus as monotypic, synonymize V. baritji with V. a. insulanicus (as a redefined V. insulanicus), elevate the subspecies of V. storri to full species (V. storri and V. ocreatus), and describe a new species from a previously identified center of endemism. The relationships among the species remain unresolved, likely as a result of fast speciation. Our study highlights the capability of large datasets to illuminate admixture patterns, biogeographic history, and species limits, even when phylogeny is not completely resolved. Furthermore, our results highlight the impact that the Cenozoic aridification of Australia had on saxicolous taxa and the role of mesic rocky escarpments as refugia. These habitats apparently allowed the persistence of lineages that became sources of colonization for arid environments.
Publisher: Pensoft Publishers
Date: 11-08-0011
Publisher: Oxford University Press (OUP)
Date: 29-01-2021
Abstract: Hybridization between species occurs more frequently in vertebrates than traditionally thought, but distinguishing ancient hybridization from other phenomena that generate similar evolutionary patterns remains challenging. Here, we used a comprehensive workflow to discover evidence of ancient hybridization between the Komodo dragon (Varanus komodoensis) from Indonesia and a common ancestor of an Australian group of monitor lizards known colloquially as sand monitors. Our data comprise $& $300 nuclear loci, mitochondrial genomes, phenotypic data, fossil and contemporary records, and past resent climatic data. We show that the four sand monitor species share more nuclear alleles with $V$. komodoensis than expected given a bifurcating phylogeny, likely as a result of hybridization between the latter species and a common ancestor of sand monitors. Sand monitors display phenotypes that are intermediate between their closest relatives and $V$. komodoensis. Biogeographic analyses suggest that $V$. komodoensis and ancestral sand monitors co-occurred in northern Australia. In agreement with the fossil record, this provides further evidence that the Komodo dragon once inhabited the Australian continent. Our study shows how different sources of evidence can be used to thoroughly characterize evolutionary histories that deviate from a treelike pattern, that hybridization can have long-lasting effects on phenotypes, and that detecting hybridization can improve our understanding of evolutionary and biogeographic patterns.[Biogeography introgression Komodo dragon phylogenetic networks phylogenomics reticulation Varanus.]
Publisher: Public Library of Science (PLoS)
Date: 06-2021
DOI: 10.1371/JOURNAL.PBIO.3001210
Abstract: Global bio ersity loss is a profound consequence of human activity. Disturbingly, bio ersity loss is greater than realized because of the unknown number of undocumented species. Conservation fundamentally relies on taxonomic recognition of species, but only a fraction of bio ersity is described. Here, we provide a new quantitative approach for prioritizing rigorous taxonomic research for conservation. We implement this approach in a highly erse vertebrate group—Australian lizards and snakes. Of 870 species assessed, we identified 282 (32.4%) with taxonomic uncertainty, of which 17.6% likely comprise undescribed species of conservation concern. We identify 24 species in need of immediate taxonomic attention to facilitate conservation. Using a broadly applicable return-on-investment framework, we demonstrate the importance of prioritizing the fundamental work of identifying species before they are lost.
Publisher: Cold Spring Harbor Laboratory
Date: 06-12-2019
DOI: 10.1101/864132
Abstract: Sexually selected traits can be expected to increase in importance when the period of sexual behavior is constrained, such as in seasonally restricted breeders. Anolis lizard male dewlaps are classic ex les of multifaceted signaling traits, with demonstrated reproductive function reflected in courtship behavior. Fitch and Hillis found a correlation between dewlap size and seasonality in mainland Anolis using traditional statistical methods. Here, we present two tests of the Fitch-Hillis Hypothesis using new phylogenetic and morphological data sets for 44 species of Mexican Anolis . A significant relationship between dewlap size and seasonality is evident in phylogenetically uncorrected analyses but erodes once phylogeny is accounted for. This loss of statistical support for a relationship between a key aspect of dewlap morphology and seasonality also occurs within a species complex ( A. sericeus group) that inhabits seasonal and aseasonal environments. Our results fail to support seasonality as a strong driver of evolution of Anolis dewlap size. We discuss the implications of our results and the difficulty of disentangling the strength of single mechanisms on trait evolution when multiple selection pressures are likely at play.
Publisher: Wiley
Date: 17-03-2020
DOI: 10.1002/ECE3.6167
Publisher: Wiley
Date: 09-12-2021
DOI: 10.1111/EVO.14403
Abstract: How biotic and abiotic factors act together to shape biological ersity is a major question in evolutionary biology. The recent availability of large datasets and development of new methodological approaches provide new tools to evaluate the predicted effects of ecological interactions and geography on lineage ersification and phenotypic evolution. Here, we use a near complete phylogenomic-scale phylogeny and a comprehensive morphological dataset comprising more than a thousand specimens to assess the role of biotic and abiotic processes in the ersification of monitor lizards (Varanidae). This charismatic group of lizards shows striking variation in species richness among its clades and multiple instances of endemic radiation in Indo-Australasia (i.e., the Indo-Australian Archipelago and Australia), one of Earth's most biogeographically complex regions. We found heterogeneity in ersification dynamics across the family. Idiosyncratic biotic and geographic conditions appear to have driven ersification and morphological evolution in three endemic Indo-Australasian radiations. Furthermore, incumbency effects partially explain patterns in the biotic exchange between Australia and New Guinea. Our results offer insight into the dynamic history of Indo-Australasia, the evolutionary significance of competition, and the long-term consequences of incumbency effects.
Publisher: Wiley
Date: 09-04-2017
DOI: 10.1111/JBI.12989
Publisher: Herpetologists League
Date: 09-2013
Publisher: Cold Spring Harbor Laboratory
Date: 28-04-2023
DOI: 10.1101/2023.04.26.537867
Abstract: Lemurs are a well-known ex le of adaptive radiation. Since colonizing Madagascar, more than 100 extant lemur species have evolved to fill the variety of ecological niches on the island. However, recent work suggests that lemurs do not exhibit one of the hallmarks of adaptive radiations: explosive speciation rates that decline over time. We test this idea using a phylogenomic dataset with broad taxonomic s ling of lemurs and their sister group, the lorisiforms of Asia and continental Africa. We find higher rates of speciation in Madagascar’s lemurs compared to lorisiforms and we confirm that lemurs did not experience an “early burst” of speciation after colonizing Madagascar. Instead, we identify three independent bursts of speciation approximately 15 million years ago that underly much of today’s lemur ersity. We demonstrate that the lemur clades with exceptionally high ersification rates have higher rates of introgression. This suggests that hybridization in these primates is not an evolutionary dead- end, but a driving force for ersification. Considering the conservation crisis affecting strepsirrhine primates, with approximately 95% of species being threatened with extinction, this phylogenomic study offers a new perspective for explaining Madagascar’s exceptional primate ersity and reveals patterns of speciation, extinction, and gene flow that will help inform future conservation decisions.
Publisher: Cold Spring Harbor Laboratory
Date: 05-10-2023
Publisher: Wiley
Date: 31-10-2022
DOI: 10.1111/AZO.12444
Abstract: Reproductive traits are critically important for understanding how organisms adapt to their respective environments. In this study, we provide information on relative litter mass (RLM) and other litter and neonate related characters of nine female Plestiodon lynxe captured in the field. We also recorded seven body dimensions in 16 neonates and 15 two‐month juveniles, and on the basis of these dimensions we compared the body shape of these two age classes to detect changes in the proportions of body parts. The average litter size (4.55) is larger than that found in other viviparous species of Plestiodon , but smaller than those of congeneric oviparous species of similar size. However, the average body size of newborns (25.49 mm) is similar to that of other oviparous and viviparous species of Plestiodon . The average RLM was relatively high (0.36). The relative size of the head and limbs becomes proportionally smaller, whereas the axilla‐groin length becomes proportionally larger in the first 2 months of life. We suggest that these changes are related to changes in locomotion and microhabitat use.
Publisher: Elsevier BV
Date: 08-2021
Publisher: Universidad Nacional Autonoma de Mexico
Date: 28-05-2020
DOI: 10.22201/FC.25942158E.2020.1.97
Abstract: Mexico, Nayarit: Municipality of El Nayar, on Federal Road 44 (Ruiz, Nayarit-Fresnillo, Zacatecas), 2.3 km south of the Zacatecas border and 2.5 km south of the Durango border (22.381564°N, 104.348159°W WGS84 2244 m elevation), 30 June 2018. This specimen (Fig. 1) represents the southeasternmost record for the species and the first record from the state of Nayarit, extending the known distribution ca. 458 km SW (airline) from the closest known locality, Rancho Madroño, Sierra Surutato, Sinaloa (McDiarmid et al. 1976). The skink was found at 13:30 h, under a piece of dried out pine bark in pine-oak forest. The specimen was collected by JALB and CIW, morphologically examined for its identification through scale counts and coloration characters by CJPV and UOGV, and deposited in the Herpetological Collection of the Museo de Zoología, Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México (MZFZ 3540).
Publisher: Magnolia Press
Date: 17-12-2017
DOI: 10.11646/ZOOTAXA.4365.2.3
Abstract: We describe a new species of Plestiodon in the P. brevirostris group from the Balsas Basin in central Mexico. It is distinguished from the other species in the group by the following combination of traits: supraoculars four interparietal enclosed posteriorly by parietals primary temporal present seventh supralabial usually contacting upper secondary temporal longitudinal dorsal scale rows around midbody 23–26 Toe-IV lamellae 13–15 limbs not overlapping when adpressed against body dorsolateral light line extending posteriorly to level of posterior end of anterior fourth of body or beyond light median line absent in all growth stages primary lateral dark lines separated medially by six dorsal scale rows and upper half of adjacent row on each side at level of midbody lower secondary dark line faint at level of neck and light coloration of supralabials extending ventrally to lip border. Analyses based on DNA sequences of three loci support the distinctiveness of the new species, as well as its sister species relationship with P. ochoterenae. The Environmental Vulnerability Score of the new species places it in the high vulnerability category.
Publisher: Herpetologists League
Date: 19-03-2021
Publisher: Elsevier BV
Date: 12-2018
DOI: 10.1016/J.YMPEV.2018.08.020
Abstract: Integrative taxonomy has been generally considered as a goal in systematics for more than a decade. Here, we employed environmental, molecular, and morphological data to evaluate the species boundaries within the short-nosed skink Plestiodon brevirostris from south-central Mexico, one member of the morphologically conservative P. brevirostris group. Our molecular dataset includes one mitochondrial and two nuclear loci. The mitochondrial fragment includes the full length of the gene coding for the NADH dehydrogenase subunit 1 protein, a segment of the gene coding for 16S ribosomal RNA, and flanking tRNAs. The nuclear dataset includes fragments of the genes coding for the megakaryoblastic leukemia 1 and RNA fingerprint 35 proteins. We employed phylogenetic reconstruction, analyses of population structure and morphological variation, and species delimitation methods (including the integration of the three kinds of data in a unified probabilistic framework) to evaluate species limits. Our results suggest that P. brevirostris represents four distinct species. The information provided by each kind of data allowed us to discern between alternative explanations for the observed patterns of geographic structure. Two of the newly recognized lineages are poorly differentiated morphologically but apparently differ in environmental preferences and are allopatric. Additionally, one lineage is microendemic and parapatric with respect to another one. Moreover, our phylogenetic analyses suggest that other taxa within the P. brevirostris group may represent species complexes. We discuss our results in the context of integrative species delimitation.
Publisher: Herpetologists League
Date: 14-12-2022
No related grants have been discovered for Carlos J. Pavón-Vázquez.