Biology subjects

Jandzik, D.

Publications and source records attributed to Jandzik, D..

7 recordsLinked to original sources

bioRxiv2025

Establishment, conservation, and innovation of dorsal determination mechanisms during the evolution of vertebrate paired appendages

Limb function requires polarized anatomy across the dorsal-ventral (DV) axis, but it is unclear when the capacity for DV differentiation of paired appendages arose in evolution. Here we define ancestral DV patterning programs in the fins of fishes. We show that the orthologue of the limb dorsal determinant, Lmx1b, is required to establish dorsality in zebrafish pectoral fins and is regulated by a conserved LARM cis-regulatory hub. However, lmx1bb expression in median fins is unaffected by removal of the LARM, suggesting its regulation is an evolutionary innovation specific to the paired appendages. Although we find the LARM is highly conserved across gnathostomes, we identify specific alteration of this region in hillstream loaches, fishes which naturally parallel "double-ventral" fin phenotypes observed in lmx1bb and LARM mutants. Altogether our findings indicate LARM-mediated dorsal identity is an ancestral feature of paired appendages that provide a prepattern for limb evolution and lineage diversification.

evolutionary biology↗

bioRxiv2022

Reconstructing the ancestral vertebrate brain using a lamprey neural cell type atlas

The vertebrate brain emerged more than [~]500 million years ago in common evolutionary ancestors. To systematically trace its cellular and molecular origins, we established a spatially resolved cell type atlas of the entire brain of the sea lamprey - a jawless species whose phylogenetic position affords the reconstruction of ancestral vertebrate traits - based on extensive single-cell RNA-seq and in situ sequencing data. Comparisons of this atlas to neural data from the mouse and other jawed vertebrates unveiled various shared features that enabled the reconstruction of the core cell type composition, tissue structures, and gene expression programs of the ancestral brain. However, our analyses also revealed key tissues and cell types that arose later in evolution. For example, the ancestral vertebrate brain was likely devoid of cerebellar cell types and oligodendrocytes (myelinating cells); our data suggest that the latter emerged from astrocyte-like evolutionary precursors on the jawed vertebrate lineage. Our work illuminates the cellular and molecular architecture of the ancestral vertebrate brain and provides a foundation for exploring its diversification during evolution.

evolutionary biology↗

bioRxiv2021

Population genomics of wall lizards reflects the dynamic history of the Mediterranean Basin

The Mediterranean Basin has experienced extensive change in geology and climate over the past six million years. Yet, the relative importance of key geological events for the distribution and genetic structure of the Mediterranean fauna remains poorly understood. Here, we use population genomic and phylogenomic analyses to establish the evolutionary history and genetic structure of common wall lizards (Podarcis muralis). This species is particularly informative because, in contrast to other Mediterranean lizards, it is widespread across the Iberian, Italian, and Balkan peninsulas, and in extra-Mediterranean regions. We found strong support for six major lineages within P. muralis, which were largely discordant with the phylogenetic relationship of mitochondrial DNA. The most recent common ancestor of extant P. muralis was likely distributed in the Italian Peninsula, and experienced an "Out-of-Italy" expansion following the Messinian salinity crisis (~5 Mya), resulting in the differentiation into the extant lineages on the Iberian, Italian and Balkan peninsulas. Introgression analysis revealed that both inter- and intraspecific gene flow have been pervasive throughout the evolutionary history of P. muralis. For example, the Southern Italy lineage has a hybrid origin, formed through admixture between the Central Italy lineage and an ancient lineage that was the sister to all other P. muralis. More recent genetic differentiation is associated with the onset of the Quaternary glaciations, which influenced population dynamics and genetic diversity of contemporary lineages. These results demonstrate the pervasive role of Mediterranean geology and climate for the evolutionary history and population genetic structure of extant species.

evolutionary biology↗

bioRxiv2020

Lamprey Lecticans Link New Vertebrate Genes to the Origin and Elaboration of Vertebrate Tissues

The evolution of vertebrates from an invertebrate chordate ancestor involved the evolution of new organs, tissues, and cell types. It was also marked by the origin and duplication of new gene families. If, and how, these morphological and genetic innovations are related is an unresolved question in vertebrate evolution. Hyaluronan is an extracellular matrix (ECM) polysaccharide important for water homeostasis and tissue structure. Vertebrates possess a novel family of hyaluronan binding proteins called Lecticans, and studies in jawed vertebrates (gnathostomes) have shown they function in many of the cells and tissues that are unique to vertebrates. This raises the possibility that the origin and/or expansion of this gene family helped drive the evolution of these vertebrate novelties. In order to better understand the evolution of the lectican gene family, and its role in the evolution of vertebrate morphological novelties, we investigated the phylogeny, genomic arrangement, and expression patterns of all lecticans in the sea lamprey (Petromyzon marinus), a jawless vertebrate. Though both P. marinus and gnathostomes have four lecticans, our phylogenetic and syntenic analyses suggest lamprey lecticans are the result of one or more cyclostome-specific duplications. Despite the independent expansion of the lamprey and gnathostome lectican families, we find highly conserved expression of lecticans in vertebrate-specific and mesenchyme-derived tissues. We also find that, unlike gnathostomes, lamprey expresses its lectican paralogs in distinct subpopulations of head skeleton precursors, potentially reflecting an ancestral diversity of skeletal tissue types. Together, these observations suggest that the ancestral pre-duplication lectican had a complex expression pattern, functioned to support mesenchymal histology, and likely played a role in the evolution of vertebrate-specific cell and tissue types.

evolutionary biology↗

bioRxiv2020

Differences in developmental potential predict the contrasting patterns of dental diversification in characiform and cypriniform fishes

Morphological diversification during adaptive radiation may depend on factors external or internal to the lineage. We provide evidence for the latter in characiform fishes (tetras and piranhas), which exhibit extensive dental diversity. Phylogenetic character mapping supported regain of lost teeth as contributing to this diversity. To test for latent potential for dentition that would facilitate its evolutionary expansion, we overexpressed a tooth initiation signal, the tumor necrosis factor pathway ligand ectodysplasin, in a model characiform, the Mexican Tetra (Astyanax mexicanus). This manipulation resulted in extensive ectopic dentition, in contrast to its previously-reported limited effect in the Zebrafish (Danio rerio). Tooth location in the Order Cypriniformes, to which the Zebrafish belongs, is much more restricted than in characiforms, a pattern that may be explained by differences in the retention of ancestral developmental potential. Our results suggest that differences in evolvability between lineages may lead to contrasting patterns of diversification.

evolutionary biology↗

bioRxiv2020

Evolution of vertebrate gill covers via shifts in an ancient Pou3f3 enhancer

Whereas the gill chambers of extant jawless vertebrates (lampreys and hagfish) open directly into the environment, jawed vertebrates evolved skeletal appendages that promote the unidirectional flow of oxygenated water over the gills. A major anatomical difference between the two jawed vertebrate lineages is the presence of a single large gill cover in bony fishes versus separate covers for each gill chamber in cartilaginous fishes. Here we find that these divergent gill cover patterns correlate with the pharyngeal arch expression of Pou3f3 orthologs. We identify a Pou3f3 arch enhancer that is deeply conserved from cartilaginous fish through humans but undetectable in lampreys, with minor sequence differences in the bony versus cartilaginous fish enhancers driving the corresponding single versus multiple gill arch expression patterns. In zebrafish, loss of Pou3f3 gene function disrupts gill cover formation, and forced expression of Pou3f3b in the gill arches generates ectopic skeletal elements resembling the multiple gill cover pattern of cartilaginous fishes. Emergence of this Pou3f3 enhancer >430 mya and subsequent modifications may thus have contributed to the acquisition and diversification of gill covers and respiratory strategies during gnathostome evolution.

developmental biology↗

bioRxiv2019

Cooption and Specialization of Endothelin Signaling Pathways Drove Elaboration of the Neural Crest in Early Vertebrates

The neural crest (NC) is a vertebrate-specific embryonic tissue that forms an array of clade-defining adult features. A key step in the formation of these diverse derivatives is the partitioning of NC cells into subpopulations with distinct migration routes and potencies1. The evolution of these developmental modules is poorly understood. Endothelin (Edn) signaling is unique to vertebrates, and performs various functions in different NC subpopulations2-5. To better understand the evolution of NC patterning, we used CRISPR/Cas9-driven mutagenesis to disrupt Edn receptors, ligands, and Dlx transcription factors in the sea lamprey, Petromyzon marinus. Lampreys and modern gnathostomes last shared a common ancestor 500 million years ago6. Thus, comparisons between the two groups can identify deeply conserved and divergent features of vertebrate development. Using Xenopus laevis to facilitate side-by-side analyses, we show here that lamprey and gnathostomes display fundamental differences in Edn signaling function. Unlike gnathostomes, both lamprey Ednrs cooperate during oropharyngeal skeleton development. Furthermore, neither paralog regulates hand transcription factors, which are required for mandible development in gnathostomes. We also identify conserved roles for Edn signaling in dlx gene regulation, pigment cell, and heart development. Together our results illustrate the stepwise neofunctionalization and specialization of this vertebrate-specific signaling pathway, and suggest key intermediate stages in the early evolution of the NC.

developmental biology↗