J. Dylan Maddox

Dr. J. Dylan Maddox

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Research Focus & Metrics

Academic Career Length

10Years (2017-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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2 April 2019 in Journal of Molluscan Studies
Verified
Journal Article
Closed access
JVJanet R Voight
Janet R Voight
BMBruce A Marshall
Bruce A Marshall
JJJenna Judge
Jenna Judge
KHKenneth M Halanych
Kenneth M Halanych
YLYuanning Li
Yuanning Li
JMJ. Dylan Maddox
J. Dylan Maddox

15 March 2021 in Journal of Experimental Biology
Verified
Journal Article
Open access
PDF file
HHHaley E Hanson
Haley E Hanson
CZCedric Zimmer
Cedric Zimmer
BKBilal Koussayer
Bilal Koussayer
ASAaron W. Schrey
Aaron W. Schrey
JMJ. Dylan Maddox
J. Dylan Maddox
LMLynn B. Martin
Lynn B. Martin
Epigenetic mechanisms may play a central role in mediating phenotypic plasticity, especially during range expansions, when populations face a suite of novel environmental conditions. Individuals may differ in their epigenetic potential (EP; their capacity for epigenetic modifications of gene expression), which may affect their ability to colonize new areas. One form of EP, the number of CpG sites, is higher in introduced house sparrows (Passer domesticus) than in native birds in the promoter region of a microbial surveillance gene, Toll-like Receptor 4 (TLR4), which may allow invading birds to fine-tune their immune responses to unfamiliar parasites. Here, we compared TLR4 gene expression from whole blood, liver and spleen in house sparrows with different EP, first challenging some birds with lipopolysaccharide (LPS), to increase gene expression by simulating a natural infection. We expected that high EP would predict high inducibility and reversibility of TLR4 expression in the blood of birds treated with LPS, but we did not make directional predictions regarding organs, as we could not repeatedly sample these tissues. We found that EP was predictive of TLR4 expression in all tissues. Birds with high EP expressed more TLR4 in the blood than individuals with low EP, regardless of treatment with LPS. Only females with high EP exhibited reversibility in gene expression. Further, the effect of EP varied between sexes and among tissues. Together, these data support EP as one regulator of TLR4 expression.

18 March 2021 in Ornithology
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Journal Article
Closed access
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JCJacob C Cooper
Jacob C Cooper
JMJ. Dylan Maddox
J. Dylan Maddox
KMKellie McKague
Kellie McKague
JBJohn M Bates
John M Bates
Africa’s montane ecosystems are noteworthy not only for their isolation but for their morphologically similar bird populations that inhabit geographically disparate localities. Many species possess range disjunctions in excess of 2,000 km and appear to represent populations that have been isolated since at least the last Ice Age, including the Northern Double-collared Sunbird (Cinnyris reichenowi). Recent work on other Afromontane birds has demonstrated substantial phylogeographic structure can exist in phenotypically similar populations, with cryptic species occurring parapatrically within the same mountain range. We explored genetic, morphological, and ecological diversity within C. reichenowi to assess whether cryptic regional diversification occurs across the disjunct portions of this species’ range. Within C. reichenowi, we find consistent patterns of morphological disparity that coincide with genetic diversification between xeric and wet montane populations within the Cameroon Line in the Western population, and clear genetic differentiation between Western and Eastern populations. Our research demonstrates that the geographically isolated populations of C. reichenowi represent different species, and that ecological diversification is shaping populations within Central Africa. We show here that two named populations should be recognized as members of a western species in the Northern Double-collared Sunbird complex: nominate Cinnyris preussi preussi in the Cameroon Line montane forests, and Cinnyris preussi genderuensis in the more xeric interior of Cameroon and the Central African Republic, likely occurring in adjacent Nigeria as well. • Northern Double-collared Sunbirds (Cinnyris reichenowi) look similar across their range, but they have a complicated taxonomic history and inhabit a wide range of habitats. • Combining genetics, morphology, and ecology, we uncovered surprising patterns of diversification, resurrecting a defunct taxon (subspecies genderuensis) while shedding light on diversification processes. • Our results show a clear separation between eastern and western populations, and ongoing diversification occurring between adjacent western groups. • This work furthers our knowledge of Afromontane diversification patterns, finding three differentiable groups within the Northern Double-collared Sunbird.

13 June 2018
Verified
Book Chapter
Open access
PDF file
JCJuan C. Castro
Juan C. Castro
JMJ. Dylan Maddox
J. Dylan Maddox
MCMarianela Cobos
Marianela Cobos
SCSixto Alfredo Imán Correa
Sixto Alfredo Imán Correa
Camu camu is a typical Amazon native fruit shrub that possesses a diploid genome, moderate genetic diversity, and population structure. The fruits accumulate several essential nutrients and synthesize L-ascorbic acid (vitamin C) in great quantities and an array of diverse secondary metabolites with corroborated in vitro and in vivo health-promoting activities. These beneficial effects include antioxidative and antiinflammatory activities, antiobesity, hypolipidemic, antihypertensive and antidiabetic effects, DNA damage and cancer protection effects, and other bioactivities. Many health-promoting phytochemicals are biosynthesized in several metabolic pathways of camu camu. Their reconstruction from the fruit transcriptome database was accomplished by our research group. These include basic metabolic pathways such as glycolysis and pentose phosphate pathway, vitamin C biosynthesis pathways, and pathways involved in secondary metabolites production. Due to their agronomic potential and fruits growing demand, recently, based on an ideotype, programs were initiated for their domestication and genetic improvement, but so far with very negligible achievements. Consequently, we propose new strategies to accelerate the processes of domestication and genetic improvement based on state of the art technologies for multiomic data analysis and innovative molecular tools.

19 June 2019
Verified
Book Chapter
Open access
PDF file
JCJuan C. Castro
Juan C. Castro
JMJ. Dylan Maddox
J. Dylan Maddox
MCMarianela Cobos
Marianela Cobos
JPJae Diana Paredes
Jae Diana Paredes
AFAnthony Jhoao Fasabi
Anthony Jhoao Fasabi
SESegundo Levi Estela
Segundo Levi Estela
The objective of this book chapter is to provide consolidated and updated scientific information about the medicinal plants of the Peruvian Amazon, which has a great richness of plants; many of these are used in folkloric medicine to treat several diseases. Recently, investigations have reported that these medicinal plants possess bioactive phytochemicals against several diseases such as diabetes, cancer, inflammation, infectious diseases, and several other health problems, thus corroborating some ethnopharmacological reports. The mechanism of action for selected bioactive phytochemicals was demonstrated at the molecular level as well as the metabolic pathways involved in their biosynthesis were described. Due to the large gap in scientific information revealed in this review, we formulated a series of strategies to close these scientific knowledge gaps and achieve a sustainable exploitation of medicinal plants in the Peruvian Amazon.

25 October 2024 in Forests
Verified
Journal Article
Open access
PDF file
JCJuan C. Castro
Juan C. Castro
SVStalin J. Vasquez-Guizado
Stalin J. Vasquez-Guizado
BVBianca E. Vigil
Bianca E. Vigil
FOFrancisco Ascue Orosco
Francisco Ascue Orosco
NRNaysha Rojas-Villa
Naysha Rojas-Villa
JMJ. Dylan Maddox
J. Dylan Maddox
The Amazonian shrub Myrciaria dubia (camu-camu) produces vitamin C-rich fruits of growing commercial interest. However, sustainable utilization requires assessment and protection of the genetic diversity of the available germplasm. This study aimed to develop and apply microsatellite markers to assess genetic diversity and construct a core collection of M. dubia germplasm from the Peruvian Amazon. Sixteen polymorphic microsatellite loci were developed using an enrichment approach. The evaluation of 336 genotypes from 43 accessions of the germplasm bank, originating from eight river basins, was conducted using these newly developed markers. Genetic diversity parameters, including observed and expected heterozygosity, were calculated. Analysis of molecular variance (AMOVA) was performed to assess the distribution of genetic variation within and among accessions and river basins. Bayesian clustering analysis was employed to infer population structure. A core collection was constructed to maximize allelic richness. High genetic diversity was observed, with heterozygosity values ranging from 0.468 to 0.644 (observed) and 0.684 to 0.817 (expected) at the river basin level. AMOVA indicated significant genetic variation within (73–86%) compared to among (14–27%) accessions and river basins. Bayesian clustering detected ten genetic clusters, with several degrees of admixture among river basins, except for the genetically homogeneous Putumayo River basin. A core collection comprising 84 plant genotypes (25% of the full collection) was established, representing 90.82% of the overall allelic diversity. These results have important implications for M. dubia conservation strategies and breeding programs, in demonstrating a need for genetic connectivity between populations but preserving unique genetic resources in isolated basins. These results validate the expected levels of diversity and population subdivision in a crop and stress the need to secure genetically diverse germplasms, underscoring the importance of thorough genetic characterization for ex situ germplasm management.