Morphological Divergence and Flow-Induced Phenotypic Plasticity in a Native Fish from Anthropogenically Altered Stream Habitats

Understanding population-level responses to human-induced changes to habitats can elucidate the evolutionary consequences of rapid habitat alteration. Reservoirs constructed on streams expose stream fishes to novel selective pressures in these habitats. Assessing the drivers of trait divergence facilitated by these habitats will help identify evolutionary and ecological consequences of reservoir habitats. We tested for morphological divergence in a stream fish that occupies both stream and reservoir habitats. To assess contributions of genetic-level differences and phenotypic plasticity induced by flow variation, we spawned and reared individuals from both habitats types in flow and no flow conditions. Body shape significantly and consistently diverged in reservoir habitats compared with streams; individuals from reservoirs were shallower bodied with smaller heads compared with individuals from streams. Significant population-level differences in morphology persisted in offspring but morphological variation compared with field-collected individuals was limited to the head region. Populations demonstrated dissimilar flow-induced phenotypic plasticity when reared under flow, but phenotypic plasticity in response to flow variation was an unlikely explanation for observed phenotypic divergence in the field. Our results, together with previous investigations, suggest the environmental conditions currently thought to drive morphological change in reservoirs (i.e., predation and flow regimes) may not be the sole drivers of phenotypic change

Shared and Unique Morphological Responses of Stream Fishes to Anthropogenic Habitat Alteration

Understanding population-level responses to novel selective pressures can elucidate evolutionary consequences of human-altered habitats. Stream impoundments (reservoirs) alter riverine ecosystems worldwide, exposing stream fishes to uncommon selective pressures. Assessing phenotypic trait divergence in reservoir habitats will be a first step in identifying the potential evolutionary and ecological consequences of stream impoundments. We tested for body shape divergence in four stream-adapted fishes found in both habitats within three separate basins. Shape variation among fishes was partitioned into shared (exhibited by all species) and unique (species-specific) responses to reservoir habitats. All fishes demonstrated consistent significant shared and unique morphological responses to reservoir habitats. Shared responses were linked to fin positioning, decreased body depths and larger caudal areas; traits likely related to locomotion. Unique responses were linked to head shape, suggesting species-specific responses to abiotic conditions or changes to their trophic ecology in reservoirs. Our results high-light how human-altered habitats can simultaneously drive similar and unique trait divergence in native populations

Rehabilitation for People with Respiratory Disease and Frailty An Official American Thoracic Society Workshop Report

People with respiratory disease have increased risk of developing frailty, which is associated with worse health outcomes. There is growing evidence of the role of rehabilitation in managing frailty in people with respiratory disease. However, several challenges remain regarding optimal methods of identifying frailty and delivering rehabilitation for this population. The aims of this American Thoracic Society workshop were to outline key definitions and concepts around rehabilitation for people with respiratory disease and frailty, synthesize available evidence, and explore how programs may be adapted to align to the needs and experiences of this population. Across two half-day virtual workshops, 20 professionals from diverse disciplines, professions, and countries discussed key developments and identified opportunities for future research, with additional input via online correspondence. Participants highlighted a “frailty rehabilitation paradox” whereby pulmonary rehabilitation can effectively reduce frailty, but programs are challenging for some individuals with frailty to complete. Frailty should not limit access to rehabilitation; instead, the identification of frailty should prompt comprehensive assessment and tailored support, including onward referral for additional specialist input. Exercise prescriptions that explicitly consider symptom burden and comorbidities, integration of additional geriatric or palliative care expertise, and/or preemptive planning for disruptions to participation may support engagement and outcomes. To identify and measure frailty in people with respiratory disease, tools should be selected on the basis of sensitivity, specificity, responsiveness, and feasibility for their intended purpose. Research is required to expand understanding beyond the physical dimensions of frailty and to explore the merits and limitations of telerehabilitation or home-based pulmonary rehabilitation for people with chronic respiratory disease and frailty.</p