Social Plasticity Enhances Signal-Preference Codivergence.

AbstractThe social environment is often the most dynamic and fitness-relevant environment animals experience. Here we tested whether plasticity arising from variation in social environments can promote signal-preference divergence-a key prediction of recent speciation theory but one that has proven difficult to test in natural systems. Interactions in mixed social aggregations could reduce, create, or enhance signal-preference differences. In the latter case, social plasticity could establish or increase assortative mating. We tested this by rearing two recently diverged species of Enchenopa treehoppers-sap-feeding insects that communicate with plant-borne vibrational signals-in treatments consisting of mixed-species versus own-species aggregations. Social experience with heterospecifics (in the mixed-species treatment) resulted in enhanced signal-preference species differences. For one of the two species, we tested but found no differences in the plastic response between sympatric and allopatric sites, suggesting the absence of reinforcement in the signals and preferences and their plastic response. Our results support the hypothesis that social plasticity can create or enhance signal-preference differences and that this might occur in the absence of long-term selection against hybridization on plastic responses themselves. Such social plasticity may facilitate rapid bursts of diversification.

Association of Geriatric Emergency Department post-discharge referral order and follow-up with healthcare utilization.

BACKGROUND: Compared with younger adults who receive care in the emergency department (ED), older patients who are discharged home have greater risk of adverse health outcomes. Connecting older adults with outpatient care following ED discharge are among the guidelines of the Geriatric Emergency Department (GED). The objective of this study was to examine the association between referral order placed during the ED visit for older adults and post-discharge follow-up to the outcomes of 72-h ED revisit, 30-day ED revisit, and 30-day all cause and unplanned hospital admission. METHODS: We conducted a retrospective cohort study. Ten accredited GEDs within one midwestern health system and all ED encounters of older adults aged 65 years and older who were discharged home from the ED between July 2019 and December 2020 were included. Predictor variables included age, sex, race, ISAR©, ED Length of Stay, post-ED referral order, and follow-up. RESULTS: Among the older adults discharged home from the ED, 17% of older adult encounters had an outpatient referral ordered in the ED, 48.4% attended a follow-up appointment. Referrals were ordered for 69 referral order types with orthopedic, family practice, and urology referrals as the top 3. In mixed-effect regression models, compared with older adults with follow-up, those with a referral order but no follow-up had 19% higher odds of having a 30-day ED revisit (OR = 1.19; 95% CI = 1.07-1.31) and 11% higher odds of having 30-day unplanned hospital admission (OR = 1.11; 95% CI = 0.98-1.26). CONCLUSIONS: Older adults who had an outpatient referral ordered prior to ED discharge and followed up had lower odds of a 30-day ED revisit and 30-day subsequent unplanned hospital admission. However, less than half of patients with a referral order attended a follow-up appointment. Designing interventions for older adults aimed at improving follow-up after an ED visit is needed.