High priority taxa

Following taxa (2 out of 6) were found to be high priority taxa to collect:

  • Z.mays subsp. huehuetenangensis
  • Z. mays subsp. parviglumis

See the priorities list here

Identified gaps for Zea genepool

(see downloads)

We found data for 3 wild Zea species (Z. diploperennis, Z. luxurians, Z. perennis), and 3 infraspecific taxa (Z. mays subsp. huehuetenangensis, Z. mays subsp. mexicana, Z. mays subsp. parviglumis), accounting to a total of 6 taxa for analysis. We have classified maize wild relatives using Maxted and Kell (2009) , which suggest the following genepools:

Primary wild relatives
Secondary wild relatives
Tertiary wild relatives
Z. mays subsp. mays cultivars and races
Z. diploperennis
Tripsacum spp.
Z. mays subsp. huehuetenangensis
Z. perennis
Z. mays subsp. mexicana
Z. luxurians
Z. mays subsp. parviglumis

The analysis dataset (download) contained 370 observations, with 142 (38%) being herbarium specimens and 228 (62%) being genebank accessions. The average number of total samples per taxon was 62 (standard deviation of 67), indicating that available data is relatively abundant, although it is concentrated in certain taxa (i.e. Z. perennis [180], Z. mays subsp. mexicana [100]), Z. mays subsp. huehetenangensis (3), along with Z. luxurians (22) present a very limited sampling and/or data availability and thus need further characterization and sampling for assessing a reliable ecogeographic evaluation on them.

The gap analysis of the Zea genepool showed that there are 2 taxa (i.e. Z. mays subsp. parviglumis, Z. mays subsp. huehuetenangensis) that are either underrepresented or not represented in any way in genebanks out of the 6 taxa under analysis and these taxa were therefore flagged as high priority species. One of these taxa presented less than 10 data points (sum of herbarium and germplasm) indicating that these species in particular need to be further collected (i.e. Z. mays subs. huehuetenangensis). Species Z. diploperennis and Z. luxurians were flagged as medium priority species as they appear to be relatively poorly conserved ex-situ. Species Z. mays subsp. mexicana was found to be relatively well conserved, so they do not require a further conservation action, along with Z. perennis, which was found as being very well represented ex-situ.

Potential sampling richness

GE View in Google Earth

Potential sampling zones

GE View in Google Earth

Z. mays subsp. parviglumis (high priority taxa) was found to be distributed in Mexico. Zones in the figures above are those in which the species is likely to exist and no genebank accessions have been collected.

Brief description of data used in the analysis

The table below shows the number of records (herbarium, germplasm, total) used per species for the Eleusine genepool gap analysis.

Genebank accessions
Herbarium samples
Zea mays subsp. huehuetenangensis
Zea mays subsp. parviglumis
Zea mays subsp. mexicana
Zea diploperennis
Zea luxurians
Zea perennis

Species’ taxonomy was reviewed using Maxted and Kell (2009) as a first stage, the GRIN taxonomical review in second place, and the Royal Botanic Gardens, Kew taxonomy database. After cross-checking and correcting both synonyms and orthography of the species’ names, a thorough georeferencing process is carried out to obtain a spatially explicit database containing as many records as possible for each species. After this, records outside continental boundaries were deleted and a final dataset was produced for analyses.

These are the 22 different collections from which data were readily available:

  1. Australian National Herbarium (CANB)
  2. Bishop Museum Natural History Specimen Data
  3. Ejemplares tipo de plantas vasculares del Herbario de la Escuela Nacional de Ciencias Biológicas, México (ENCB, IPN)
  4. EKY_Darwincore
  5. EURISCO, The European Genetic Resources Search Catalogue
  6. Harvard University Herbaria
  7. Herbario del Instituto de Ecología, A.C., México (IE-BAJIO)
  8. Herbario del Instituto de Ecología, A.C., México (IE-XAL)
  9. Herbarium Berolinense
  10. Instituto de Ciencias Naturales
  11. IPK Genebank
  12. Missouri Botanical Garden
  13. NMNH Botany Collections
  14. NSW herbarium collection
  15. Repatriación de datos del Herbario de Arizona (ARIZ)
  16. The AAU Herbarium Database
  17. The System-wide Information Network for Genetic Resources (SINGER)
  18. United States National Plant Germplasm System Collection
  19. University of California Botanical Garden DiGIR provider
  20. USDA PLANTS Database
  21. USU-UTC Specimen Database
  22. Vascular Plant Type Specimens


Climatic niche model for Z. diploperennis
Climatic niche model for Z. luxurians
Climatic niche model for Z. mays subsp. mexicana
Climatic niche model for Z. mays subsp. parviglumis
Climatic niche model for Z. perennis
Zea potential collecting zones
Zea potential collecting richness zones
Predicted species richness under current climatic conditions
Predicted species richness under future climatic conditions
Changes on predicted species richness due to climate change
Sampling density (200km cell size) for germplasm accessions
Sampling density (200km cell size) for herbarium samples
Conservation priorities list for Zea genepool
Dataset used for this analysis

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5 Comments to “Zea genepool”

  1. Heike Vibrans says:

    Upon revising the Zea gap analysis, I noticed that you don’t have data from the largest germplasm collections of the group, which would be the CIMMYT and the maize collections of the Mexican agricultural institutions (for example, of the INIFAP or the Agricultural University of Chapingo, which hosts a germplasm collection), or of the National Herbarium, MEXU. I suggest that incorporating data from these sources would rather change the picture.

    Unfortunately, much of these realworld data are not yet available in webaccessible formats, which makes dataharvesting from afar an undertaking with rather a lot of holes in it. The Balsas teosinte (parviglumis) is not really undercollected – there are certainly more than 100 germplasm and herbarium collections; huehuetenangensis is a different matter, as it had small populations to begin with, and most of these are apparently gone. A widely cited work on the distribution of teosinte in Mexico (http://www.bioversityinternational.org/publications/Web_version/266/ch3.htm) cites quite a few Balsas (Zea mays ssp. parviglumis) collections, and that was more than 10 years ago.

    You may be interested in the fact that the CONABIO (www.conabio.gob.mx) is currently funding a large and ambitious maize and teosinte germplasm collection project (here is the announcement: http://www.conabio.gob.mx/institucion/proyectos/doctos/Recolecta.pdf; several projects are underway).

    Regards, and good luck with your project,

    Heike Vibrans

  2. Julian says:

    Hi Heike.

    Many thanks for your comment and feedback. Data availability issues are one of the most frequent bottlenecks when working with collections, and when trying to assess gaps. We consider that if a sample is so hidden that anyone in the world cannot access it, it is certainly a Gap. However, we hope that national-level institutions start making their datasets freely available in order to make our results far more relevant and applied at national-levels.

    Is there any way in which we can contact owners of the datasets you mention (besides the CIMMYT one, for which we have access through SINGER)? or a way for you to share such data (if you have so?) with us?

  3. Jeff Ross-Ibarra says:

    I have some trouble believing some of these results. First of all, as of today, GRIN has 52 active (and 174 inactive) germplasm accessions of parviglumis, compared to 170 (total) for mexicana, and only 13 (only 4 active!) for perennis, which is nearly the opposite of the conclusions reached here. It also appears that some pertinent references might have been missed, e.g.


    Given these discrepancies, I wonder at the graphs. I know of several parviglumis populations, for example, that occur outside the potential distribution map. Any thoughts on why the differences between these numbers and GRIN?

  4. Jeff says:

    I’d also like to point out some issues with the Zea analysis. It’s not clear to me whether USDA GRIN was checked for germplasm (though #18 on the list would have me believe it was), because my interpretation of the results in GRIN lead me to nearly opposite conclusions: 226 parviglumis accessions available (52 active and available for ordering), but only 13 Zea perennis accessions (4 active) and 26 Zea luxurians accessions (only 2 active!).

    Moreover, some of the distributions are surprising — Zea diploperennis, for example, seems to have been collected in several parts of Mexico, and gap analysis shows it’s potential distribution throughout Jalisco. But to my knowledge, Zea diploperennis is only known from the Sierra de Manantlan Biosphere reserve. The potential distributions of other wild taxa also seem off. In fact, we have a pretty good record of collections of most of these taxa — I urge those interested to read Ruiz et al (2001), Ruiz et al. (2008), and Sanchez-Gonzalez & Ruiz Corral (1997), the latter of which is publicly available online from CIMMYT:


    Ruiz JA, Sanchez JDJ, Aguilar M (2001) Potential geographical distribution of teosinte in Mexico: A GIS approach. Maydica 46: 105-110.

    Ruiz Corral JA, Duran Puga N, Sanzhez Gonzalez JD, Ron Parra J, Gonzalez Eguiarte DR et al. (2008) Climatic adaptation and ecological descriptors of 42 Mexican maize races. Crop Sci 48: 1502-1512.

    Sánchez González JJ, Ruiz Corral JA (1997) Teosinte distribution in Mexico. In: Serratos JA, Willcox MC, Castillo González F, editors. Gene flow among maize landraces, improved maize varieties and teosinte: implications for transgenic maize. Mexico City: CIMMYT. pp. 18-36.

  5. Julian says:

    Hi Jeff,

    Many thanks for your pretty interesting and useful feedback. It’s actually what we seek through the portal. I have not been noticed by my webmaster whether there’s a comment which is still unposted, and I do not see any comment unattended. I will check deeper though, as I wouldn’t like to lose these important feedbacks.

    One of the issues with our approach is that we strongly depend on freely available data from databases (e.g. GRIN, SINGER, EURISCO, GBIF). We thus acknowledge there should be hidden accessions that might change the priorities picture. Moreover, we also depend on the quality of such information and definitely on the presence of location data (e.g. lat/lon, or locality and country names) within the accessions/specimens. In our approach, samples with no georreferences cannot be assessed in any way as they do not provide any useful information (neither geographical, nor environmental, or genetic, or agronomic) more than a taxon name. So, we just discard them in one of the first steps. Perhaps that’s where most of the Z. parviglumis accessiones went?

    Moreover, the method also takes into account the geographical and environmental sampling/collection bias versus the potential area in which the taxon is distributed. So, if the taxon is potentially distributed within a considerably big area, no matter if you have 5,000 accessions, but if they have been collected at only one site (or within an small part of the potential area) then your taxon will be flagged as underrepresented.

    Some of the data is still hidden, and you point out additional resources which we will query in order to re-assess the Zea gap analyses and correct the results. We know there’s a lot of work to be done yet, and we continue working and improving our results. This information you give us is actually what we need to be more accurate. Many thanks again for your comment.

    Let me know whether you would like to contribute with specific feedback (genebank or herbarium data, and or taxonomical issues). We are attempting to collate as much data as we can.

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