Research ArticleAPPLIED ECOLOGY

Parasite biodiversity faces extinction and redistribution in a changing climate

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Science Advances  06 Sep 2017:
Vol. 3, no. 9, e1602422
DOI: 10.1126/sciadv.1602422
  • Fig. 1 Gradients of species richness and predicted turnover through extinction and redistribution.

    (A) Current distribution of parasite species richness (S) in our data set is calculated by stacking binary outputs of species distribution models (see point distributions in fig. S5). (B) Turnover (in species units) is measured by following the same procedure from 18 combinations of GCMs and RCPs for the year 2070 and taking the average difference (ΔS) from 2016. (C) Proportional change (ΔS/S) is most severe in low-diversity areas where parasite richness is predicted to increase as a consequence of latitudinal shifts.

  • Fig. 2 Comparative IUCN “Red List” breakdowns by clade.

    (A) Breakdowns are given by habitat loss categories from now to 2070: 0 to 25%, least concern; 25 to 50%, vulnerable; 50 to 80%, endangered; 80 to 100%, critically endangered. (B to I) Conservation classifiers are broken down for eight major clades: (B) Acanthocephala (n = 14 spp.), (C) Astigmata (n = 18), (D) Cestoda (n = 25), (E) Ixodida (n = 141), (F) Nematoda (n = 147), (G) Phthiraptera (n = 5), (H) Siphonaptera (n = 67), and (I) Trematoda (n = 40).

  • Fig. 3 Primary, secondary, and compounded extinction rates (%) for major helminth clades.

    Error bars represent lower and upper bounds to estimation based on the Thomas et al. method and errors in the Dobson method, and means between the two interval ends are shown in bars for (left to right) acanthocephalans, cestodes, nematodes, and trematodes. Cause of extinction is broken down into primary extinction (direct impacts of climate change, no dispersal), secondary extinction (coextinction with hosts, calculated in text S1), and a combined risk (total). Scenarios are presented for (A) no dispersal and (B) full dispersal capacity for parasites. Most helminths face high risk when accounting for coextinction, although acanthocephalans consistently appear much less threatened.

  • Table 1 Habitat loss and projected extinction risk by dispersal scenario and clade.

    Values are averaged across all general circulation models (GCMs) and RCP scenarios (46), and the percentage of species committed to extinction is calculated using the three Thomas et al. (6) SAR methods. Percentiles are calculated from species-level averages of GCMs and RCPs (that is, all variance is interspecific).

    CladeNspeciesHabitat loss (mean)Habitat loss range (5th to 95th percentile)% Committed to extinction
    0% dispersal
    Acanthocephala14−16.6%(−50.6%, −0.2%)3.8%/4.4%/4.9%
    Astigmata18−19.0%(−43.6%, −4.0%)4.4%/5.1%/5.3%
    Cestoda25−13.6%(−29.1%, −2.9%,)4.0%/3.6%/3.7%
    Ixodida141−31.9%(−57.0%, −1.9%)8.1%/9.2%/9.8%
    Nematoda147−28.0%(−74.4%, −2.6%)5.4%/7.9%/9.3%
    Phthiraptera5−55.8%(−71.5%, −34.4%)10.5%/18.5%/19.3%
    Siphonaptera67−40.6%(−69.5%, −11.0%)10.0%/12.2%/12.9%
    Trematoda40−17.8%(−47.4%, −0.4%)3.8%/4.8%/6.0%
    100% dispersal
    Acanthocephala14+48.8%(−10.4%, +129.0%)0.21%/0.54%/0.60%
    Astigmata18+13.8%(−41.2%, +64.4%)1.3%/2.0%/2.3%
    Cestoda25+57.1%(+3.7%, +131.1%)0.07%/0.07%/0.07%
    Ixodida141−8.6%(−54.1%, +67.7%)4.9%/5.7%/6.4%
    Nematoda147+18.7%(−53.6%, +87.6%)1.3%/2.5%/3.3%
    Phthiraptera5+110.5%(−57.7%, +514.8%)4.6%/6.2%/7.4%
    Siphonaptera67−5.0%(−50.0%, +43.8%)1.9%/4.1%/4.6%
    Trematoda40+82.2%(−30.4%, +242.4%)0.11%/1.0%/1.2%

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/9/e1602422/DC1

    text S1. Primary, secondary, and compounded extinction rates.

    text S2. Canonical and MaxEnt approaches to the SAR.

    text S3. A more restrictive analysis based on 50+ point-per-species models.

    table S1. Host specificity and parasite species richness.

    table S2. Thomas best-case scenario coextinction rates.

    table S3. Thomas worst-case scenario coextinction rates.

    table S4. Thomas total coextinction rates.

    table S5. Urban best-case scenario coextinction rates.

    table S6. Urban worst-case scenario coextinction rates.

    table S7. Urban total coextinction rates.

    table S8. Cumulative extinctions with dispersal.

    table S9. Cumulative extinctions with dispersal.

    table S10. 50+ points subanalysis-based habitat loss rates.

    table S11. Source data (Excel).

    table S12. Source data (Excel).

    table S13. Source data (Excel).

    fig. S1. Final data set breakdown by source and clade.

    fig. S2. Example presentation of species distribution and conservation status on PEARL.

    fig. S3. Loss of native habitat broken down by RCP and GCM.

    fig. S4. Trade-offs between biodiversity loss and emergence across parasite clades.

    fig. S5. Sources and distribution of occurrence data.

    fig. S6. Loss of native habitat broken down by feature classes and regularization multiplier.

    fig. S7. Visualizing spatial bias in species richness gradients.

    fig. S8. Parasite richness gradients by human health concern.

  • Supplementary Materials

    This PDF file includes:

    • text S1. Primary, secondary, and compounded extinction rates.
    • text S2. Canonical and MaxEnt approaches to the SAR.
    • text S3. A more restrictive analysis based on 50+ point-per-species models.
    • table S1. Host specificity and parasite species richness.
    • table S2. Thomas best-case scenario coextinction rates.
    • table S3. Thomas worst-case scenario coextinction rates.
    • table S4. Thomas total coextinction rates.
    • table S5. Urban best-case scenario coextinction rates.
    • table S6. Urban worst-case scenario coextinction rates.
    • table S7. Urban total coextinction rates.
    • table S8. Cumulative extinctions with dispersal.
    • table S9. Cumulative extinctions with dispersal.
    • table S10. 50+ points subanalysis-based habitat loss rates.
    • fig. S1. Final data set breakdown by source and clade.
    • fig. S2. Example presentation of species distribution and conservation status on PEARL.
    • fig. S3. Loss of native habitat broken down by RCP and GCM.
    • fig. S4. Trade-offs between biodiversity loss and emergence across parasite clades.
    • fig. S5. Sources and distribution of occurrence data.
    • fig. S6. Loss of native habitat broken down by feature classes and regularization multiplier.
    • fig. S7. Visualizing spatial bias in species richness gradients.
    • fig. S8. Parasite richness gradients by human health concern.

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