Bimodal spore release heights in the water column enhance local retention and population connectivity of bull kelp, Nereocystis luetkeana

Dispersal of reproductive propagules determines recruitment patterns and connectivity among populations and can influence how populations respond to major disturbance events. Dispersal distributions can depend on propagule release strategies. For instance, the bull kelp, Nereocystis luetkeana, can release propagules (spores) from two heights in the water column ("bimodal release"): at the water surface, directly from the reproductive tissues (sori) on the kelp's blades, and near the seafloor after the sori abscise and sink through the water column. N. luetkeana is a foundation species that occurs from central California to Alaska and is experiencing unprecedented levels of population declines near its southern range limit. We know little of the kelp's dispersal distributions, which could influence population recovery and restoration. Here, we quantify how bimodal spore release heights affect dispersal outcomes based on a numerical model specifically designed for N. luetkeana. The model incorporates oceanographic conditions typical of the species' coastal range and kelp biological traits. With bimodal release heights, 34% of spores are predicted to settle within 10 m of the parental alga and 60% are predicted to disperse beyond 100 m. As an annual species, bimodal release heights can facilitate the local regeneration of adults within a source kelp forest while also supporting connectivity among multiple forests within broader bull kelp metapopulations. To leverage this pattern of bimodal spore dispersal in bull kelp restoration management, directing resources toward strategically located focal populations that can seed other ones could amplify the scale of recovery

Reconstructing the reproductive mode of an Ediacaran macro-organism.

Enigmatic macrofossils of late Ediacaran age (580-541 million years ago) provide the oldest known record of diverse complex organisms on Earth, lying between the microbially dominated ecosystems of the Proterozoic and the Cambrian emergence of the modern biosphere. Among the oldest and most enigmatic of these macrofossils are the Rangeomorpha, a group characterized by modular, self-similar branching and a sessile benthic habit. Localized occurrences of large in situ fossilized rangeomorph populations allow fundamental aspects of their biology to be resolved using spatial point process techniques. Here we use such techniques to identify recurrent clustering patterns in the rangeomorph Fractofusus, revealing a complex life history of multigenerational, stolon-like asexual reproduction, interspersed with dispersal by waterborne propagules. Ecologically, such a habit would have allowed both for the rapid colonization of a localized area and for transport to new, previously uncolonized areas. The capacity of Fractofusus to derive adult morphology by two distinct reproductive modes documents the sophistication of its underlying developmental biology.This work has been supported by the Natural Environment Research Council [grant numbers NE/I005927/1 to C.G.K., NE/J5000045/1 to J.J.M., NE/L011409/1 to A.G.L. and NE/G523539/1 to E.G.M.], and a Henslow Junior Research Fellowship from Cambridge Philosophical Society to A.G.L.This is the author accepted manuscript. The final version is available from NPG via http://dx.doi.org/10.1038/nature1464

The "resolution" of verb meaning in context

textIt is well-known that the meaning of a word often changes depending on the context in which the word is used. Determining the appropriate interpretation for a word occurrence requires a knowledge of the range of possible meanings for that word, and consideration of those possibilities given available contextual evidence. However, there is still much to be learned about the nature of our lexical knowledge, as well as how we make use of that knowledge in the course of language comprehension. I report on a series of three experiments that explore these issues. I begin with the question of how precise our perceptions of word meaning in context really are. In Experiment 1, I present a Magnitude Estimation study in which I obtain judgments of meaning-in-context similarity over pairs of intransitive verb occur- rences, such as The kid runs / The cat runs, or The cat runs / The lane runs. I find that participants supply a large range of very specific similarity judgments, that judgments are quite consistent across participants, and that these judgments can be at least partially predicted even by simple measures of contextual properties, such as subject noun animacy and human similarity ratings over pairs of subject nouns. However, I also find that while some participants supply a great variety of ratings, many participants supply only a few unique values during the task. This suggests that some individuals are making more fine-grained judgments than others. These differences in response granularity could stem from a variety of sources. However, the offline nature of Experiment 1 does not enable direct examination of the comprehension process, but rather focuses on its end result. In Experiment 2, I present a Speed-Accuracy Tradeoff study that explores the earliest stages of meaning-in-context resolution to better understand the dynamics of the comprehension process itself. In particular, I focus on the timecourse of meaning resolution and the question of whether verbs carry context-independent default interpretations that are activated prior to semantic integration. I find, consistent with what has previously been shown for nouns, that verbs do in fact carry such a default meaning, as can be seen in early false alarms to stimuli such as The dawn broke -- Something shattered. These default meanings appear to reflect the most frequent interpretation of the verb. While these default meanings are likely an emergent effect of repeated exposure to frequent interpretations of a verb, I hypothesize that they additionally support a shallow semantic processing strategy. Recently, a growing body of work has begun to demonstrate that our language comprehension is often less than exhaustive and less than maximally accurate -- people often vary the depth of their processing. In Experiment 3, I explore changes in depth of semantic processing by making an explicit connection to research on human decision making, particularly as regards questions of strategy selection and effort- accuracy tradeoffs. I present a semantic judgment task similar to that used in Experiment 2, but incorporating design principles common in studies on decision making, such as response-contingent financial payoffs and trial-by-trial feedback on response accuracy. I show that participants' preferences for deep and shallow semantic processing strategies are predictably influenced by factors known to affect decision making in other non-linguistic domains. In lower-risk situations, participants are more likely to accept default meanings even when they are not contextually supported, such as responding "True" to stimuli such as The dawn broke -- Something shattered, even without the presence of time pressure. In Experiment 3, I additionally show that participants can adjust not only their processing strategies but also their stimulus acceptance thresholds. Stimuli were normed for truthfulness, i.e. how strongly implied (or entailed) a probe sentence was given its context sentence. Some stimuli in the task posessed an intermediate degree of truthfulness, akin to implicature, as in The log burned -- Something was dangerous (truthfulness 4.55/7). Across 3 conditions, the threshold separating "true" from "false" stimuli was moved such that stimuli such as the example just given would be evaluated differently in different conditions. Participants rapidly learned these threshold placements via feedback, indicating that their perceptions of meaning-in-context, as expressed via the range of possible conclusions that could be drawn from the verb, could vary dynamically in response to situational constraints. This learning was additionally found to occur both faster and more accurately under increased levels of risk. This thesis makes two primary contributions to the literature. First, I present evidence that our knowledge of verb meanings is at least two-layered -- we have access to a very information-rich base of event knowledge, but we also have a more schematic level of representation that is easier to access. Second, I show that these different sources of information enable different semantic processing strategies, and that moreover the choice between these strategies is dependent upon situational characteristics. I additionally argue for the more general relevance of the decision making literature to the study of language processing, and suggest future applications of this approach for work in experimental semantics and pragmatics.Linguistic

Auxiliary selection and the typical properties of subjects

I present a semantic analysis of two types of auxiliary selection patterns. Italian, Dutch, French, and Old Japanese have a pattern in which auxiliary selection is conditioned by verb class, and there is also a pattern active in many Italo-Romance dialects where the distribution of the two auxiliaries is dependent upon the person and number of the subject. I present a unified analysis of these two patterns that is rooted in prototypical vs. atypical subject properties, particularly with respect to affectedness, person, and number. I show that auxiliary selection indicates a typicality distinction on the part of the subject with respect to prominence mismatches along various semantic scales.Linguistic

Complications Occurring Through 5 Years Following Primary Intraocular Lens Implantation for Pediatric Cataract

Importance Lensectomy with primary intraocular lens (IOL) implantation is often used in the management of nontraumatic pediatric cataract, but long-term data evaluating the association of age and IOL location with the incidence of complications are limited. Objective To describe the incidence of complications and additional eye surgeries through 5 years following pediatric lensectomy with primary IOL implantation and association with age at surgery and IOL location. Design, Setting, and Participants This prospective cohort study used Pediatric Eye Disease Investigator Group cataract registry data from 61 institution- and community-based practices over 3 years (June 2012 to July 2015). Participants were children younger than 13 years without baseline glaucoma who had primary IOL implantation (345 bilateral and 264 unilateral) for nontraumatic cataract. Data analysis was performed between September 2021 and January 2023. Exposures Lensectomy with primary IOL implantation. Main Outcome and Measures Five-year cumulative incidence of complications by age at surgery (<2 years, 2 to <4 years, 4 to <7 years, and 7 to <13 years) and by IOL location (sulcus vs capsular bag) were estimated using Cox proportional hazards models. Results The cohort included 609 eyes from 491 children (mean [SD] age, 5.6 [3.3] years; 261 [53%] male and 230 [47%] female). Following cataract extraction with primary IOL implantation, a frequent complication was surgery for visual axis opacification (VAO) (cumulative incidence, 32%; 95% CI, 27%-36%). Cumulative incidence was lower with anterior vitrectomy at the time of IOL placement (12%; 95% CI, 8%-16%) vs without (58%; 95% CI, 50%-65%), and the risk of undergoing surgery for VAO was associated with not performing anterior vitrectomy (hazard ratio [HR], 6.19; 95% CI, 3.70-10.34; P < .001). After adjusting for anterior vitrectomy at lens surgery, there were no differences in incidence of surgery for VAO by age at surgery (<2 years, HR, 1.35 [95% CI, 0.63-2.87], 2 to <4 years, HR, 0.86 [95% CI, 0.44-1.68], 4 to <7 years, HR, 1.06 [95% CI, 0.72-1.56]; P = .74) or by capsular bag vs sulcus IOL fixation (HR, 1.22; 95% CI, 0.36-4.17; P = .75). Cumulative incidence of glaucoma plus glaucoma suspect by 5 years was 7% (95% CI, 4%-9%), which did not differ by age after controlling for IOL location and laterality. Conclusions and Relevance In this cohort study, a frequent complication following pediatric lensectomy with primary IOL was surgery for VAO, which was associated with primary anterior vitrectomy not being performed but was not associated with age at surgery or IOL location. The risk of glaucoma development across all ages at surgery suggests a need for long-term monitoring