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Taxones de colección prioritaria
Los siguientes taxones (2 de 6) fueron identificados como taxones de colección prioritaria:
- Z.mays subsp. huehuetenangensis
- Z. mays subsp. parviglumis
Ver toda la lista de prioridades
Vacíos de colección identificados en el acervo genético de Zea
(ver descargas)
Se encontraron datos para 3 especies silvestres de Zea(Z. diploperennis, Z. luxurians, Z. perennis), y 3 taxones intraespecíficos (Z. mays subsp. huehuetenangensis, Z. mays subsp. mexicana, Z. mays subsp. parviglumis), para un total de 6 taxones bajo análisis. Los parientes silvestres del maíz han sido clasificados de acuerdo a Maxted and Kell (2009) , como se muestra en la siguiente tabla:
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Parientes silvestres primarios
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Parientes silvestres secundarios
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Parientes silvestres terciarios
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Z. mays subsp. mays cultivars and races
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Z. diploperennis
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Tripsacum spp.
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Z. mays subsp. huehuetenangensis
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Z. perennis
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Z. mays subsp. mexicana
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Z. luxurians
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Z. mays subsp. parviglumis
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El set de datos utilizado para el análisis (descargar) contiene 370 observaciones, de las cuales 142 (38%) corresponden a especimenes de herbario y 228 (62%) a acccesiones de bancos de germoplasma. El número promedio de observaciones por taxón es de 62 (desviación estándar: 67), lo cual indica una buena disponibilidad de datos. En algunos taxones puede notarse la concentración de registros, como es el caso de Z. perennis [180] y Z. mays subsp. mexicana [100], Z. mays subsp. huehetenangensis (3), y Z. luxurians (22) presentan un muestreo muy limitado y/o una baja disponibilidad de datos. Estos dos últimos taxones en especial, requieren ser caracterizados y muestreados con el fin de hacer evaluaciones ecogeográficas confiables.
El análisis de vacíos en el acervo genético de Zea encontró que 2 taxones (i.e. Z. mays subsp. parviglumis, Z. mays subsp. huehuetenangensis) se encuentran subrepresentados o no represetandos en bancos de germoplasma. Una de estas especies cuenta con menos de 10 registros (suma de herbario y germoplasma), indicando que esta especie en particular requiere ser colectada (i.e. Z. mays subs. huehuetenangensis). Z. diploperennis y Z. luxurians fueron identificadas como especies de prioridad media, ya que aparecen relativamente poco conservada ex situ. La especie Z. mays subsp. mexicana fue identificada como relativamente bien conservada, por lo tanto no requiere ser colectada, así como Z. perennis, la cual se encuentra muy bien representada ex situ.
Potential sampling richness
Potential sampling zones
Z. mays subsp. parviglumis (taxón de colección prioritaria) se encuentra distribuida en México. Las zonas con color en el mapa anterior, corresponden a las zonas en donde la especie puede existir y aún no se han colectado accesiones para bancos de germoplasma.
Breve descripción de los datos usados en el análisis
La siguiente tabla muestra el número de registros (herbario, germoplasma y total) y usados para este análisis.
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Especie
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Germoplasma
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Herbario
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Total
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| Zea mays subsp. huehuetenangensis |
3
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0
|
3
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| Zea mays subsp. parviglumis |
0
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24
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24
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| Zea mays subsp. mexicana |
43
|
57
|
100
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| Zea diploperennis |
11
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30
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41
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| Zea luxurians |
9
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13
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22
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| Zea perennis |
162
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18
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180
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En una primera etapa, la taxonomía de las especies fue revisada usando Maxted and Kell (2009), seguidamente en GRIN taxonomical y finalmente en The Royal Botanic Gardens, Kew taxonomy database. Después de la verificación y correción tanto de ortografía como sinonímias, se llevó a cabo un profundo proceso de georreferenciación con el fin de obtener una base de datos que almacenara la mayor cantidad posible de registros por especie con información geográfica (i.e. coordenadas espaciales). Posteriormente, los registros que se encontraron por fuera de los límites continentales fueron eliminados y finalmente se obtuvo el set de datos para analizar.
A continuación las 22 colecciones cuyos datos se encuentran disponibles libremente:
- Australian National Herbarium (CANB)
- Bishop Museum Natural History Specimen Data
- Ejemplares tipo de plantas vasculares del Herbario de la Escuela Nacional de Ciencias Biológicas, México (ENCB, IPN)
- EKY_Darwincore
- EURISCO, The European Genetic Resources Search Catalogue
- Harvard University Herbaria
- Herbario del Instituto de Ecología, A.C., México (IE-BAJIO)
- Herbario del Instituto de Ecología, A.C., México (IE-XAL)
- Herbarium Berolinense
- Instituto de Ciencias Naturales
- IPK Genebank
- Missouri Botanical Garden
- NMNH Botany Collections
- NSW herbarium collection
- Repatriación de datos del Herbario de Arizona (ARIZ)
- The AAU Herbarium Database
- The System-wide Information Network for Genetic Resources (SINGER)
- United States National Plant Germplasm System Collection
- University of California Botanical Garden DiGIR provider
- USDA PLANTS Database
- USU-UTC Specimen Database
- Vascular Plant Type Specimens
Descargas
| Modelo de nicho climático para Z. diploperennis | |
| Modelo de nicho climático para Z. luxurians | |
| Modelo de nicho climático para Z. mays subsp. mexicana | |
| Modelo de nicho climático para Z. mays subsp. parviglumis | |
| Modelo de nicho climático para Z. perennis | |
| Zonas de colecta potencial para Zea | |
| Riqueza de sitios de colección potenciales para Zea | |
| Riqueza potencial de especies bajo condiciones climáticas actuales | |
| Riqueza potencial de especies bajo condiciones climáticas futuras (año 2050, escenario SRES-A2a) | |
| Cambios en la riqueza potencial de especies debido al cambio climático | |
| Densidad de muestras (tamaño de celda: 200km) para las accesiones de germoplasma | |
| Densidad de muestras (tamaño de celda: 200km) para los registros de herbario | |
| Lista de prioridades de conservación para el acervo genético de Zea | |
| Set de datos utilizados para este análisis |
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
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?
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.
http://www.cimmyt.org/english/docs/proceedings/geneflow/Geneflow_TeosDistr.pdf
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?
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:
http://www.cimmyt.org/english/docs/proceedings/geneflow/Geneflow_TeosDistr.pdf
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.
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.