Geology topics

John G. Ewen

Publications and source records attributed to John G. Ewen.

3 recordsLinked to original sources

USGS2026

Improving the use of expert opinion in disease risk analysis for conservation translocations

Conservation translocations are subject to considerable uncertainty and risk, of which disease is one of the most recognized. To address disease risks, several protocols for qualitative disease risk analysis (qDRA) exist and are used for responsible conservation translocation planning. Existing qDRA protocols usually rely on expert judgment, but they lack quantitative aggregation of elicited estimates, transparent treatment of uncertainty, and explicit comparison of alternative disease risk management pathways. We added these factors to a qDRA for translocation of a charismatic species that is extinct in the wild, the sihek (Guam kingfisher) ( Todiramphus cinnamominus ). We asked a panel of seven independent experts to quantify their judgment of risks of pathogen release, exposure, and consequences for seven pathogen hazards under three translocation management scenarios. Experts suggested that implementing a full biosecurity protocol would reduce risk for several pathogen hazards but would have variable effectiveness (11–65% depending on the hazard). There was substantial uncertainty associated with individual experts and noise among different experts, showing the potential for error if decisions are based on single-point judgments (i.e., providing judgment of a central tendency without accounting for uncertainty) from one expert or on collaborative consensus of multiple experts, as is current practice.

Conservation Biology↗

USGS2025

Self‐sustaining populations are a conservation vision, not an operational objective

It is common for species conservation plans to identify the establishment or maintenance of a “self-sustaining population” as an objective. However, this statement vaguely conflates different formulations and interpretations of population viability, management costs, and cultural preferences for non-invasive population management. Hidden value judgments and assumptions about these components can create disagreement and conflict among partners. Thus, although a simple statement about “achieving self-sustaining populations” can be a powerful strategic vision, evoking important shared values, it will not be effective as an operational objective for conservation decision making. Best practices in decision making emphasize the importance of fundamental objectives that are clear, unambiguous, and operational. Conservation planners may be better served by replacing the self-sustaining concept with better-defined fundamental objectives using quantitative statements about viability and clearly laying out ecological, economic, and cultural values.

Conservation Science and Practice↗

USGS2014

Global phylogeography of the avian malaria pathogen Plasmodium relictum based on MSP1 allelic diversity

Knowing the genetic variation that occurs in pathogen populations and how it is distributed across geographical areas is essential to understand parasite epidemiology, local patterns of virulence, and evolution of host-resistance. In addition, it is important to identify populations of pathogens that are evolutionarily independent and thus ‘free’ to adapt to hosts and environments. Here, we investigated genetic variation in the globally distributed, highly invasive avian malaria parasite Plasmodium relictum , which has several distinctive mitochondrial haplotyps (cyt b lineages, SGS1, GRW11 and GRW4). The phylogeography of P. relictum was accessed using the highly variable nuclear gene merozoite surface protein 1 (MSP1), a gene linked to the invasion biology of the parasite. We show that the lineage GRW4 is evolutionarily independent of GRW11 and SGS1 whereas GRW11 and SGS1 share MSP1 alleles and thus suggesting the presence of two distinct species (GRW4 versus SGS1 and GRW11). Further, there were significant differences in the global distribution of MSP1 alleles with differences between GRW4 alleles in the New and the Old World. For SGS1, a lineage formerly believed to have both tropical and temperate transmission, there were clear differences in MSP1 alleles transmitted in tropical Africa compared to the temperate regions of Europe and Asia. Further, we highlight the occurrence of multiple MSP1 alleles in GRW4 isolates from the Hawaiian Islands, where the parasite has contributed to declines and extinctions of endemic forest birds since it was introduced. This study stresses the importance of multiple independent loci for understanding patterns of transmission and evolutionary independence across avian malaria parasites.

Ecography↗