Biology subjects

Kerr, J.

Publications and source records attributed to Kerr, J..

5 recordsLinked to original sources

bioRxiv2026

Extinction risk in terrestrial vertebrates is associated with niche limits that reflect climatic vulnerability

Anthropogenic climate and land-use change are driving an emerging extinction crisis that is expected to intensify in the future. Species climatic niche limits shape their sensitivity to these pressures, potentially leading to disproportionate extinction risk among more climatically vulnerable species. We test whether realized climatic niche limits are associated with current and projected extinction risk across >23,000 terrestrial vertebrate species. We assessed the phylogenetic structure of thermal and aridity niche limits and related them to IUCN threat status and simulated future extinctions. We show that realized niche limits are phylogenetically conserved, indicating evolutionary clustering of climatic tolerances. Species with colder upper thermal limits were more likely to be classified as threatened across taxa. Aridity niche limits show weaker and less consistent relationships with current threat status. Simulated extinction scenarios reveal taxon-specific patterns of climatic niche loss compared to random species extinctions. We also show significant reductions in phylogenetic diversity relative to randomized expectations based on simulated species extinctions. We find that extinction risk is systematically associated with species climatic niche limits, reflecting evolutionary constraints on environmental tolerance. These results indicate that future extinctions will disproportionately affect climatically vulnerable lineages, with cascading consequences for phylogenetic diversity and ecosystem functioning.

ecology↗

bioRxiv2025

Positive joint work redistribution in running: the role of plantar flexor fatigue and the effect of advanced footwear technology

Over the course of a near-maximal effort 10 km run, positive mechanical work decreases at the ankle and increases at the knee. Although plantar flexor fatigue is believed to be responsible for the proximal shift in mechanical work generation, this has yet to be confirmed experimentally. PurposeTo 1) determine the effect of plantar flexor fatigue on lower limb positive joint work during running and 2) determine the effect of running shoes on this relationship. MethodsTrained male runners (n = 12) were analyzed over two 30 s runs at their 10 km race pace, without and with local plantar flexor fatigue induced via a calf-raise protocol to a level commensurate with that accumulated over an exhaustive run ([~]24% reduction in peak torque). Both the unfatigued and fatigued runs were performed in a traditional shoe and in advanced footwear technology on an instrumented treadmill while three-dimensional motion capture and ground reaction force data were collected. ResultsPlantar flexor fatigue led to a redistribution of joint work, with lower positive ankle work (p < 0.001), greater positive knee work (p = 0.001), and similar positive hip work (p = 0. 550) in the fatigued run as compared to the unfatigued run. The relative positive joint contributions shifted proximally with fatigue (ankle - 4%, knee +3%); however, this shift was not influenced by shoe condition (p > 0.05). ConclusionPlantar flexor fatigue contributes to the proximal redistribution of positive joint work during running. However, the adoption of a suboptimal gait strategy appears to occur regardless of whether a runner wears a traditional shoe or advanced running footwear technology.

bioengineering↗

bioRxiv2024

Identification of an Outbreak of Bivalve Transmissible Neoplasia in Soft-Shell Clams (Mya arenaria) in the Puget Sound Using Hemolymph and eDNA Surveys

Bivalve transmissible neoplasia (BTN) is one of three known types of naturally transmissible cancer-- cancers in which the whole cancer cells move from individual to individual, spreading through natural populations. BTN is a lethal leukemia-like cancer that has been observed throughout soft-shell clam (Mya arenaria) populations on the east coast of North America, with two distinct sublineages circulating at low enzootic levels in New England, USA, and Prince Edward Island, Canada. Major cancer outbreaks likely due to Mya arenaria BTN (MarBTN) were reported in 1980s and the 2000s and the disease has been observed since the 1970s, but it has not been observed in populations of this clam species on the US west coast. In 2022, we collected soft-shell clams from several sites in Puget Sound, Washington, USA, and unexpectedly found high prevalence of BTN in two sites (Triangle Cove on Camano Island and near Stanwood in South Skagit Bay). Prevalence of BTN increased in subsequent years, reaching >75% in both sites in 2024, while it was not observed in other sites, suggesting the early stages of a severe disease outbreak following recent introduction. We observed that these cancer cells contain several somatic transposing insertion sites found only in the USA-sublineage of MarBTN, showing that it likely was recently transplanted from New England to this location. We then developed a sensitive environmental DNA (eDNA) assay, using qPCR to target somatic mutations in the MarBTN mitogenome, and showed that MarBTN can be detected in seawater at Triangle Cove, as well as several kilometers outside of the cove. We then used this assay to survey 50 sites throughout Puget Sound, confirming that the disease can be detected at high levels at Triangle Cove and South Skagit Bay, and showing that it extends beyond these known sites. However, while normal soft-shell clam mtDNA was widely detected, MarBTN was undetectable throughout most of Puget Sound and currently remains limited to the South Skagit Bay area and north Port Susan. These results identify a previously unknown severe outbreak of a transmissible cancer due to long-distance transplantation of disease from another ocean, and they demonstrate the utility of eDNA methods to track the spread of BTN through the environment.

ecology↗

bioRxiv2024

Range geographies, not functional traits, explain convergent range and phenology shifts under climate change

Climate change may introduce conditions beyond species tolerances; to survive, species must avoid these extremes. Phenological shifts are one strategy, as species move their activity or life history events in time to avoid extreme conditions. Species may also shift in space, moving their ranges poleward to escape extremes. However, whether species are more likely to exhibit one or both strategies, and whether this can be predicted based on a species functional traits, is unknown. Using a powerful macroecological dataset of European and North American odonate observations, we assessed range and phenology shifts between two time periods (1980-2002 and 2008-2018) to measure the strength and direction of the association between responses. Species with the greatest poleward range shifts also showed the largest phenological shifts toward earlier annual activity periods, with half of all species shifting in both space and time. This response was consistent across continents, despite highly divergent land use and biogeographical histories in these regions. Surprisingly, species range and phenology shifts were not related to functional traits; rather, southern species shifted their range limits more strongly, while increasing temperature variability hindered range shifts. By reducing risk through phenological shifts, the resulting larger populations may be more likely to disperse and expand species ranges. Species shifting in both space and time may be more resilient to extreme conditions, although further work integrating abundance data is needed. We also identified a small number of species (approximately 10%) that failed to shift at all; these species are likely to be particularly vulnerable to climate change, and should be prioritized for conservation intervention.

ecology↗

bioRxiv2019

A Model-Based Cost-Effectiveness Analysis of an Exercise Program for Lung Cancer Survivors Following Curative-Intent Treatment

RationaleThe Institute of Medicine emphasizes care in the post-treatment phase of the cancer survivorship continuum. Physical exercise has been shown to be effective in improving physical function and quality of life in cancer survivors; however, its cost-effectiveness in lung cancer survivors is not well established. ObjectiveWe performed a model-based cost-effectiveness analysis of an exercise intervention in lung cancer survivors following curative-intent treatment. MethodsWe constructed a Markov model to simulate the impact of the Lifestyle Interventions and Independence for Elders (LIFE) exercise intervention compared to usual care for stage I-IIIA lung cancer survivors. Costs and utility benefit of exercise were extracted from the LIFE study. Baseline utilities, transition probabilities, and survival were modeled. We calculated and considered incremental cost-effectiveness ratios (ICERs) <$100,000/quality-adjusted life-year (QALY) as cost-effective, and assessed model uncertainty using one-way and probabilistic sensitivity analyses. ResultsOur base-case model found that the LIFE exercise program would increase overall cost by $4,740 and effectiveness by 0.06 QALYs compared to usual care, and have an ICER of $79,504/QALY. The model was most sensitive to the cost of the exercise program, probability of increasing exercise, and utility benefit related to exercise. At a willingness-to-pay threshold of $100,000/QALY, the LIFE exercise program had a 71% probability of being cost-effective compared to 27% for usual care. When we included opportunity costs, the LIFE exercise program had an ICER of $179,774/QALY, exceeding the cost-effectiveness threshold. ConclusionsA simulation of the LIFE exercise program in lung cancer survivors following curative-intent treatment demonstrates cost-effectiveness from an organization but not societal perspective. Strategies to effectively increase exercise remotely may be more cost-effective than in-facility strategies for these patients.

epidemiology↗