Paper · 2020 · Conservation Genetics

Predicting the geographic origin of Spanish Cedar (Cedrela odorata L.) based on DNA variation

Kristen N. Finch; Richard C. Cronn; Marianella C. Ayala Richter; et al.

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claims
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verbatim quotes
23
citations
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Open access · cc-by

Abstract

Abstract The legality of wood products often depends on their origin, creating a need for forensic tools that verify claims of provenance for wood products. The neotropical tree species Cedrela odorata (Spanish cedar) is economically valuable for its wood and faces threats of overexploitation. We developed a 140 SNP assay for geographic localization of C. odorata specimens. Target capture and short-read sequencing of 46 C. odorata specimens allowed us to identify 140 spatially informative SNPs that differentiate C. odorata specimens by latitude, temperature, and precipitation. We assessed the broad applicability of these SNPs on 356 specimens from eight Cedrela species, three tissue types, and a range of DNA mass inputs. Origin prediction error was evaluated with discrete and continuous spatial assignment methods focusing on C. odorata specimens. Discrete classification with random forests readily differentiated specimens originating in Central America versus South America (5.8% error), while uncertainty increased as specimens were divided into smaller regions. Continuous spatial prediction with SPASIBA showed a median prediction error of 188.7 km. Our results demonstrate that array SNPs and resulting genotypes accurately validate C. odorata geographic origin at the continental scale and show promise for country-level verification, but that finer-scale assignment likely requires denser spatial sampling. Our study underscores the important role of herbaria for developing genomic resources, and joins a growing list of studies that highlight the role of genomic tools for conservation of threatened species.

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Claims 5

Method / resourceobservedoriginal resultmeasured

Claim · model-written summary

The assay identified 140 spatially informative SNPs.

Taxon
Cedrela odorataCedrela odoratae1
Outcome
spatially informative SNPse0
Value
140e0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Cedrela odorata
Cedrela odorata · TaxonForest & Kim Starr · CC BY 3.0 · Wikimedia Commons ↗

Verbatim

e0

“identify 140 spatially informative SNPs that differentiate C. odorata specimens by latitude, temperature, and precipitation”

✓ located verbatim in the source · abstract, characters 459–582 · show in text ↑
e1

“Cedrela odorata (Spanish cedar)”

✓ located verbatim in the source · abstract, characters 186–217 · show in text ↑
Method / resourceobservedoriginal resultmeasured

Claim · model-written summary

Random forests classified Central versus South American specimens with 5.8% error.

Taxon
Cedrela odorataCedrela odoratae1
Outcome
errore0
Value
5.8%e0
Comparator
Central America versus South Americae0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Cedrela odorata
Cedrela odorata · TaxonForest & Kim Starr · CC BY 3.0 · Wikimedia Commons ↗

Verbatim

e0

“Discrete classification with random forests readily differentiated specimens originating in Central America versus South America (5.8% error)”

✓ located verbatim in the source · abstract, characters 859–1000 · show in text ↑
e1

“Cedrela odorata (Spanish cedar)”

✓ located verbatim in the source · abstract, characters 186–217 · show in text ↑
Method / resourceobservedoriginal resultmeasured

Claim · model-written summary

Classification uncertainty increased for smaller regions.

Taxon
Cedrela odorataCedrela odoratae1
Outcome
uncertaintye0
Direction
increasede0
Comparator
smaller regionse0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Cedrela odorata
Cedrela odorata · TaxonForest & Kim Starr · CC BY 3.0 · Wikimedia Commons ↗

Verbatim

e0

“uncertainty increased as specimens were divided into smaller regions”

✓ located verbatim in the source · abstract, characters 1008–1076 · show in text ↑
e1

“Cedrela odorata (Spanish cedar)”

✓ located verbatim in the source · abstract, characters 186–217 · show in text ↑
Method / resourceobservedoriginal resultmeasured

Claim · model-written summary

SPASIBA had median spatial prediction error of 188.7 km.

Taxon
Cedrela odorataCedrela odoratae1
Outcome
median prediction errore0
Value
188.7 kme0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Cedrela odorata
Cedrela odorata · TaxonForest & Kim Starr · CC BY 3.0 · Wikimedia Commons ↗

Verbatim

e0

“Continuous spatial prediction with SPASIBA showed a median prediction error of 188.7 km”

✓ located verbatim in the source · abstract, characters 1078–1165 · show in text ↑
e1

“Cedrela odorata (Spanish cedar)”

✓ located verbatim in the source · abstract, characters 186–217 · show in text ↑
Recommendationauthor interpretationoriginal resultbasis n/a

Claim · model-written summary

Finer-scale assignment likely requires denser spatial sampling.

Taxon
Cedrela odorataCedrela odoratae1
Outcome
denser spatial samplinge0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Cedrela odorata
Cedrela odorata · TaxonForest & Kim Starr · CC BY 3.0 · Wikimedia Commons ↗

Verbatim

e0

“finer-scale assignment likely requires denser spatial sampling”

✓ located verbatim in the source · abstract, characters 1363–1425 · show in text ↑
e1

“Cedrela odorata (Spanish cedar)”

✓ located verbatim in the source · abstract, characters 186–217 · show in text ↑