Data from: Life histories and conservation of long-lived reptiles, an illustration with the American Crocodile (Crocodylus acutus)

1. Successful species conservation is dependent on adequate estimates of population dynamics, but age-specific demographics are generally lacking for long-lived iteroparous species. Accurate demographic information allows estimation of population growth rate, as well as projection of future population sizes and quantitative analyses of fitness trade-offs involved in evolution of life-history strategies. 2. Here, a long-term capture-recapture study was conducted from 1978-2014 on the American crocodile (Crocodylus acutus) in southern Florida. Over the study period, 7,427 hatchlings were marked and 380 individuals were recaptured for as many as 25 years. We estimated survival to be strongly age-dependent with hatchlings having the lowest survival rates (16%) but increasing to nearly 90% at adulthood based on mark-recapture models. More than 5% of the female population were predicted to be reproductive by age 8 years; the age-specific proportion of reproductive females steadily increased until age 18 when more than 95% of females were predicted to be reproductive. Population growth rate, estimated from a Leslie-Lefkovich stage-class model, showed a positive annual growth rate of 4% over the study period. 3. Using a sensitivity analysis, we revealed that the adult stage, as expected was the most critical stage for population growth rate; however, the survival of younger crocodiles before they became reproductive, also had a surprisingly high elasticity. We found that variation in age-specific fecundity has very limited impact population growth rate in American crocodiles. 4. We used a comparative approach to show that the original life history strategy of American crocodiles is actually shared by other large, long-lived reptiles: while adult survival rates always have a large impact on population growth, this decreases with declining growth rates, in favor of a higher elasticity of the juvenile stage. 5. Crocodiles, as a large, long-lived and highly fecund species deviate from the usual association of life-histories of “slow” species. Current management practices are focused on nests and hatchling survival; however, protection efforts that extend to juvenile crocodiles would be most effective for conservation of the species, especially in an ever-developing landscape

Life histories and conservation of long-lived reptiles, an illustration with the American crocodile ( Crocodylus acutus )

International audienc

Dynamic changes in human single‐cell transcriptional signatures during fatal sepsis

Systemic infections, especially in patients with chronic diseases, may result in sepsis: an explosive, uncoordinated immune response that can lead to multisystem organ failure with a high mortality rate. Patients with similar clinical phenotypes or sepsis biomarker expression upon diagnosis may have different outcomes, suggesting that the dynamics of sepsis is critical in disease progression. A within-subject study of patients with Gram-negative bacterial sepsis with surviving and fatal outcomes was designed and single-cell transcriptomic analyses of peripheral blood mononuclear cells (PBMC) collected during the critical period between sepsis diagnosis and 6 h were performed. The single-cell observations in the study are consistent with trends from public datasets but also identify dynamic effects in individual cell subsets that change within hours. It is shown that platelet and erythroid precursor responses are drivers of fatal sepsis, with transcriptional signatures that are shared with severe COVID-19 disease. It is also shown that hypoxic stress is a driving factor in immune and metabolic dysfunction of monocytes and erythroid precursors. Last, the data support CD52 as a prognostic biomarker and therapeutic target for sepsis as its expression dynamically increases in lymphocytes and correlates with improved sepsis outcomes. In conclusion, this study describes the first single-cell study that analyzed short-term temporal changes in the immune cell populations and their characteristics in surviving or fatal sepsis. Tracking temporal expression changes in specific cell types could lead to more accurate predictions of sepsis outcomes and identify molecular biomarkers and pathways that could be therapeutically controlled to improve the sepsis trajectory toward better outcomes

Crocodile capture data 1978-2014

Crocodile capture data 1978-2014 at Turkey Point/South Florida, US