Seasonality of endemic COVID-19.

Successive waves of infection by SARS-CoV-2 have left little doubt that this virus will transition to an endemic disease. Foreknowledge of when to expect seasonal surges is crucial for healthcare and public health decision-making. However, the future seasonality of COVID-19 remains uncertain. Evaluating its seasonality is complicated due to the limited years of SARS-CoV-2 circulation, pandemic dynamics, and varied interventions. In this study, we project the expected endemic seasonality by employing a phylogenetic ancestral and descendant state approach that leverages long-term data on the incidence of circulating HCoV coronaviruses. Our projections indicate asynchronous surges of SARS-CoV-2 across different locations in the northern hemisphere, occurring between October and January in New York and between January and March in Yamagata, Japan. This knowledge of spatiotemporal surges leads to medical preparedness and enables the implementation of targeted public health interventions to mitigate COVID-19 transmission.IMPORTANCEThe seasonality of COVID-19 is important for effective healthcare and public health decision-making. Previous waves of SARS-CoV-2 infections have indicated that the virus will likely persist as an endemic pathogen with distinct surges. However, the timing and patterns of potentially seasonal surges remain uncertain, rendering effective public health policies uninformed and in danger of poorly anticipating opportunities for intervention, such as well-timed booster vaccination drives. Applying an evolutionary approach to long-term data on closely related circulating coronaviruses, our research provides projections of seasonal surges that should be expected at major temperate population centers. These projections enable local public health efforts that are tailored to expected surges at specific locales or regions. This knowledge is crucial for enhancing medical preparedness and facilitating the implementation of targeted public health interventions.

Characterization and distribution of kisspeptins, kisspeptin receptors, GnIH, and GnRH1 in the brain of the protogynous bluehead wrasse (Thalassoma bifasciatum).

The kisspeptin and gonadotropin-inhibitory hormone (GnIH) systems regulate the hypothalamic-pituitary-gonadal (HPG) axis in a broad range of vertebrates through direct or indirect effects on hypothalamic/preoptic gonadotropin-releasing hormone (GnRH) neurons and pituitary gonadotropes. These systems are sensitive to environmental factors, including social conditions, and may assist in relaying environmental signals to the HPG axis in a potentially broad range of taxa. In this study, we characterized expression of kisspeptin-system genes (kiss1, kiss2, kissr1, and kissr2), gnih, and gnrh1 in the brain of the bluehead wrasse (Thalassoma bifasciatum), an important teleost model of socially-controlled sex change. We analyzed cDNA sequences and examined transcript distributions in the brain using in situ hybridization (ISH) to determine if expression occurs in reproductively-relevant and conserved regions. Expression of kiss1 was detected in the habenula, lateral hypothalamic nucleus (LHn), and preoptic area (POA), while kiss2 was expressed in the dorsal hypothalamus, with sporadic signal in the POA. Expression of kissr1 was detected in the POA, habenula, and LHn, while kissr2 expression was widespread. Gnih mRNA was detected in the posterior periventricular nucleus (NPPv), and gnrh1 neurons localized to the POA. Neurons expressing kissr2 and gnih co-regionalized in the NPPv, while kissr1, kissr2, and gnrh1 co-regionalized in the POA. Double-label ISH revealed very close proximity between kissr1 and gnrh1 neurons, suggesting potential communication between the kisspeptin and GnRH1 systems through these interneurons. These expression patterns are generally conserved and suggest that if kisspeptins do signal GnRH1 neurons, the interaction is indirect, possibly through neurons adjacent to GnRH1. With this foundation in place, future studies can help determine the interactions among these systems and whether these peptides assist in transducing social changes into a shift from female to male sexual function.

Estrogenic signaling and sociosexual behavior in wild sex-changing bluehead wrasses, Thalassoma bifasciatum.

Estrogenic signaling is an important focus in studies of gonadal and brain sexual differentiation in fishes and vertebrates generally. This study examined variation in estrogenic signaling (1) across three sexual phenotypes (female, female-mimic initial phase [IP] male, and terminal phase [TP] male), (2) during socially-controlled female-to-male sex change, and (3) during tidally-driven spawning cycles in the protogynous bluehead wrasse (Thalassoma bifasciatum). We analyzed relative abundances of messenger RNAs (mRNAs) for the brain form of aromatase (cyp19a1b) and the three nuclear estrogen receptors (ER) (ERα, ERßa, and ERßb) by qPCR. Consistent with previous reports, forebrain/midbrain cyp19a1b was highest in females, significantly lower in TP males, and lowest in IP males. By contrast, ERα and ERßb mRNA abundances were highest in TP males and increased during sex change. ERßa mRNA did not vary significantly. Across the tidally-driven spawning cycle, cyp19a1b abundances were higher in females than TP males. Interestingly, cyp19a1b levels were higher in TP males close (~1 h) to the daily spawning period when sexual and aggressive behaviors rise than males far from spawning (~10-12 h). Together with earlier findings, our results suggest alterations in neural estrogen signaling are key regulators of socially-controlled sex change and sexual phenotype differences. Additionally, these patterns suggest TP male-typical sociosexual behaviors may depend on intermediate rather than low estrogenic signaling. We discuss these results and the possibility that an inverted-U shaped relationship between neural estrogen and male-typical behaviors is more common than presently appreciated.

Comparing the dietary niche overlap and ecomorphological differences between invasive Hemidactylus mabouia geckos and a native gecko competitor.

Hemidactylus mabouia is one of the most successful, widespread invasive reptile species and has become ubiquitous across tropical urban settings in the Western Hemisphere. Its ability to thrive in close proximity to humans has been linked to the rapid disappearance of native geckos. However, aspects of Hemidactylus mabouia natural history and ecomorphology, often assumed to be linked with this effect on native populations, remain understudied or untested. Here, we combine data from ∂15N and ∂13C stable isotopes, stomach contents, and morphometric analyses of traits associated with feeding and locomotion to test alternate hypotheses of displacement between H. mabouia and a native gecko, Phyllodactylus martini, on the island of Curaçao. We demonstrate substantial overlap of invertebrate prey resources between the species, with H. mabouia stomachs containing larger arthropod prey as well as vertebrate prey. We additionally show that H. mabouia possesses several morphological advantages, including larger sizes in feeding-associated traits and limb proportions that could offer a propulsive locomotor advantage on vertical surfaces. Together, these findings provide the first support for the hypotheses that invasive H. mabouia and native P. martini overlap in prey resources and that H. mabouia possess ecomorphological advantages over P. martini. This work provides critical context for follow-up studies of H. mabouia and P. martini natural history and direct behavioral experiments that may ultimately illuminate the mechanisms underlying displacement on this island and act as a potential model for other systems with Hemidactylus mabouia invasions.

Telomere Roles in Fungal Genome Evolution and Adaptation.

Telomeres form the ends of linear chromosomes and usually comprise protein complexes that bind to simple repeated sequence motifs that are added to the 3' ends of DNA by the telomerase reverse transcriptase (TERT). One of the primary functions attributed to telomeres is to solve the "end-replication problem" which, if left unaddressed, would cause gradual, inexorable attrition of sequences from the chromosome ends and, eventually, loss of viability. Telomere-binding proteins also protect the chromosome from 5' to 3' exonuclease action, and disguise the chromosome ends from the double-strand break repair machinery whose illegitimate action potentially generates catastrophic chromosome aberrations. Telomeres are of special interest in the blast fungus, Pyricularia, because the adjacent regions are enriched in genes controlling interactions with host plants, and the chromosome ends show enhanced polymorphism and genetic instability. Previously, we showed that telomere instability in some P. oryzae strains is caused by novel retrotransposons (MoTeRs) that insert in telomere repeats, generating interstitial telomere sequences that drive frequent, break-induced rearrangements. Here, we sought to gain further insight on telomeric involvement in shaping Pyricularia genome architecture by characterizing sequence polymorphisms at chromosome ends, and surrounding internalized MoTeR loci (relics) and interstitial telomere repeats. This provided evidence that telomere dynamics have played historical, and likely ongoing, roles in shaping the Pyricularia genome. We further demonstrate that even telomeres lacking MoTeR insertions are poorly preserved, such that the telomere-adjacent sequences exhibit frequent presence/absence polymorphism, as well as exchanges with the genome interior. Using TERT knockout experiments, we characterized chromosomal responses to failed telomere maintenance which suggested that much of the MoTeR relic-/interstitial telomere-associated polymorphism could be driven by compromised telomere function. Finally, we describe three possible examples of a phenomenon known as "Adaptive Telomere Failure," where spontaneous losses of telomere maintenance drive rapid accumulation of sequence polymorphism with possible adaptive advantages. Together, our data suggest that telomere maintenance is frequently compromised in Pyricularia but the chromosome alterations resulting from telomere failure are not as catastrophic as prior research would predict, and may, in fact, be potent drivers of adaptive polymorphism.

Testing ontogenetic patterns of sexual size dimorphism against expectations of the expensive tissue hypothesis, an intraspecific example using oyster toadfish (Opsanus tau).

Trade-offs associated with sexual size dimorphism (SSD) are well documented across the Tree of Life. However, studies of SSD often do not consider potential investment trade-offs between metabolically expensive structures under sexual selection and other morphological modules. Based on the expectations of the expensive tissue hypothesis, investment in one metabolically expensive structure should come at the direct cost of investment in another. Here, we examine allometric trends in the ontogeny of oyster toadfish (Opsanus tau) to test whether investment in structures known to have been influenced by strong sexual selection conform to these expectations. Despite recovering clear changes in the ontogeny of a sexually selected trait between males and females, we find no evidence for predicted ontogenetic trade-offs with metabolically expensive organs. Our results are part of a growing body of work demonstrating that increased investment in one structure does not necessarily drive a wholesale loss of mass in one or more organs.

Cradles and museums of Antarctic teleost biodiversity.

Isolated in one of the most extreme marine environments on Earth, teleost fish diversity in Antarctica's Southern Ocean is dominated by one lineage: the notothenioids. Throughout the past century, the long-term persistence of this unique marine fauna has become increasingly threatened by regional atmospheric and, to a lesser extent oceanic, warming. Developing an understanding of how historical temperature shifts have shaped source-sink dynamics for Antarctica's teleost lineages provides critical insight for predicting future demographic responses to climate change. We use a combination of phylogenetic and biogeographic modelling to show that high-latitude Antarctic nearshore habitats have been an evolutionary sink for notothenioid species diversity. Contrary to expectations from island biogeographic theory, lower latitude regions of the Southern Ocean that include the northern Antarctic Peninsula and peripheral island archipelagos act as source areas to continental diversity. These peripheral areas facilitate both the generation of new species and repeated colonization of nearshore Antarctic continental regions. Our results provide historical context to contemporary trends of global climate change that threaten to invert these evolutionary dynamics.