Biology subjects

Soto-Angel, J. J.

Publications and source records attributed to Soto-Angel, J. J..

5 recordsLinked to original sources

bioRxiv2026

Precocious reproduction in the ctenophore Mnemiopsis leidyi is modulated by conspecific density and food availability

Precocious reproduction, prior to the acquisition of the final adult morphology, occurs in a variety of animals and represents a distinct life-history strategy with important consequences for growth and survival. Larval reproduction is far rarer and usually restricted to groups that go through metamorphosis. In ctenophores, Carl Chun described dissogeny more than 130 years ago, a distinctive life-history pattern involving larval and adult reproductive periods separated by gonadal regression. Yet, the potential plasticity of larval reproduction in ctenophores remains unresolved. Here, we developed a method to follow and quantify reproductive output in Mnemiopsis leidyi larvae and tested environmental factors that may regulate precocious reproduction. We found that conspecific density strongly influences its onset: low-density, well-fed animals can bypass reproduction at the cydippid stage and develop rapidly into the lobed form, whereas higher density promotes precocious reproduction. Food availability and associated growth rate also contribute but cannot alone explain the observed differences. Once reproduction is established, however, high conspecific density suppresses reproductive output, an effect reproduced by exposure to seawater incubated with high M. leidyi densities, consistent with water-borne chemical communication. Salinity and light conditions further modulate spawning. Together, our results reveal substantial environmental plasticity in precocious reproduction in M. leidyi, reconcile long-standing contradictory observations of ctenophore development, and highlight how environmental cues can reshape reproductive life-history transitions.

ecology↗

bioRxiv2026

Revisiting Hydractiniidae (Hydrozoa): Mitogenomic Insights into the Diversity, Systematics and Life-Cycle Evolution of North Atlantic and Arctic Species

Hydractiniidae is a diverse family of colonial hydrozoans exhibiting substantial variation in colony organization, reproduction and life-cycle strategies, including species with and without a medusa stage. Several hydractiniids are also established model organisms, yet species boundaries and distributions remain incompletely resolved, limiting comparisons of reproductive and developmental traits across taxa. Here, we combine morphological and molecular data to reassess hydractiniid diversity, species identities, and life-cycle variation in material from the North Atlantic and Arctic Ocean. We integrate detailed observations of colonies and reproductive structures with DNA barcoding and mitochondrial genomes to evaluate species boundaries and provide molecular support for taxonomic identifications. Our results confirm 10 species in the study area, occurring from shallow waters to 2600 m depth and from coastal fjords to deep-sea hydrothermal vents. We further show that some historical species identifications and distribution records require reassessment. We establish a new genus for Arctic hydractiniid species (Bonneviactinia gen. nov.) and reassign two species to Schuchertinia. Mapping reproductive strategies onto the phylogeny reveals a broad pattern of increasing retention of medusa characters, from fixed sporosacs through reduced and fixed medusoids and non-liberated eumedusoids to fully developed, free-swimming feeding medusae, suggesting a progressive evolutionary trajectory in life-cycle complexity across Hydractiniidae. Furthermore, we clarify the identity of Podocoryna carnea and, through rearing experiments from polyp stage to medusae, characterize its morphological variation and developmental stages. By linking morphologically documented specimens and vouchers to genetic data, we establish reference resources that will facilitate future taxonomic, phylogenetic and biodiversity studies, including molecular surveys of marine communities. Together, these results demonstrate the value of integrative taxonomy for resolving hydractiniid diversity and provide a comparative foundation for investigating the evolution of reproductive strategies and life-cycle complexity in Medusozoa.

evolutionary biology↗

bioRxiv2025

The 3D architecture of the ctenophore aboral organ and the evolution of complex integrative centers in animals

The ability to sense and respond to environmental cues is fundamental to animal behavior and survival. In ctenophores - early-branching marine animals - a syncytial nerve net underlies complex behaviors such as geotaxis, feeding, and escape. At the center of this system is the aboral organ (AO), a dense sensory hub that detects motion, light, and pressure and coordinates ciliary movement. However, the AOs cellular architecture and its integration with the nerve net remain poorly understood. Here, using volume electron microscopy in Mnemiopsis leidyi, we reveal that the syncytial nerve net converges and condenses around the AO, forming synaptic connections with diverse effector cells. We annotated 17 distinct cell types, including candidate light and pressure sensors, novel ciliated and secretory cells, and non-synaptic vesicle-rich cells likely involved in volume transmission. Our data shows that signal processing within the AO relies on both synaptic and non-synaptic communication. Gene expression profiling of conserved transcription factors indicates that the AO is a functionally convergent, evolutionarily distinct sensory structure that retains minimal homology. Our findings redefine the ctenophore AO as a highly integrated, multilayered sensory system critical for behavioral regulation.

evolutionary biology↗

bioRxiv2024

Reverse development in the ctenophore Mnemiopsis leidyi

Reverse development, or the ability to rejuvenate by morphological reorganization into the preceding life cycle stage is thought to be restricted to a few species within Cnidaria. To date, the cnidarian Turritopsis dohrnii is the only known species capable of undergoing reverse development after the onset of sexual reproduction. Here, we demonstrate that the ctenophore Mnemiopsis leidyi is capable of reversal from mature lobate to early cydippid when fed following a period of stress. Our findings illuminate central aspects of ctenophore development, ecology, and evolution, and show the high potential of M. leidyi as a new model system to study reverse development and rejuvenation. Besides shedding light on the plasticity of developmental programs, our results raise fundamental questions about early animal development, body plans and life cycles.

ecology↗

bioRxiv2022

Syncytial nerve net in a ctenophore sheds new light on the early evolution of nervous systems

A fundamental breakthrough in neurobiology has been the formulation of the neuron doctrine by Santiago Ramon y Cajal, which states that the nervous system is composed of discrete individual cells. Electron microscopy later confirmed the doctrine and allowed the identification of synaptic connections. Here we use volume electron microscopy and 3D reconstructions to characterize the nerve net of a cydippid-phase ctenophore, belonging to one of the earliest-branching animal lineages. We found that neurons of its subepithelial nerve net do not follow Cajals neuron doctrine but instead show a continuous plasma membrane forming a syncytium. This is more similar to the reticulate theory of the nervous system put forward by Camillo Golgi. Additionally, we were able to identify new sensory cell types and describe simple neuro-sensory circuits for cydippid-phase ctenophores. Together with the ctenophore-specific synaptic architecture and the presence of an extensive repertoire of lineage-specific neuropeptides our morphological data provide substantial evidence for the independent evolution of the nervous system of ctenophores and the remaining animals.

evolutionary biology↗