Genetic erosion and extinction threat of the old world cottons, Gossypium L .

1. Genetic erosion and extinction threat of the old world cottons, Gossypium L. Vojtěch Holubec Dept. of Gene Bank Research Institute of Crop Production, Prague – Ruzyně, Czech Republic

2. Why? and Aim • a case study • alarming situation already in the past • IPGRI internship Aim: to assess the needs for collection and conservation of wild African and Arabian cottons

3. Introduction • Wild species of Gossypium occupy both Americas, Africa, Asia (Arabia) and Australia • While American and Australian species are quite well known, there was a very little knowledge on African and Arabian spp. • It was expected, those localities/spp. could have been endangered

4. Material and methods • Important herbaria have been visited: K, BM, P, BR, COI, LISC, MO, NA, NY, US • Data were recorded into a dbf file. • Revision of species • Collection sites were localized (geographical gazetteer) • Species distribution was plotted to the maps in the Miller's oblate stereographic projection in the scale 1:50 mil. (Miller, 1953). • "The vegetation map of Africa" was used to match the species distribution with various mapping units. The borders of the mapping phytochoria were digitized and drawn into the distribution maps. The program and maps were generated at the Computing Center of Texas A & M University. Number of collected herbarium records of Gossypium and Gossypioides species of Africa and Arabia in visited herbaria HerbariumBMBRCOIKLISCMONANYPUSpfSum No. of exsiccata741133925189816151694622905

5. Results and discussion 1. Taxonomy of African and Arabian species of cotton • Taxonomic treatment of the genus Gossypium was accepted as was proposed by Fryxell (1979) with the following changes: • - Gossypium herbaceum var. africanum was accepted at the subspecies level as proposed by Mauer (1954) • - subdivision of G.somalense into species G.somalense, G.benadirense and G.bricchettii was adopted as suggested by Vollesen (1987) • - G.trifurcatum described by Vollesen (1987) was included in the subgenus Gossypium. • Keys for determination of African and Arabian species were designed.

6. 1.3. The species concept (Africa, Arabia) subgenus Sturtia (R.Brown) Todaro genome section Hibiscoidea Todaro Gossypium triphyllum (Harv. ex Harv.  Sonder) Hochr............B2 subgenus Gossypium Gossypium trifurcatumVollesen...........................................? section Gossypium subsection Gossypium Gossypium arboreum L.......................................................A2 Gossypium herbaceum L.....................................................A1 Gossypium herbaceum L. ssp. africanum (Watt) Mauer............A1 subsection Anomala Todaro Gossypium anomalum Wawr. ex Wawr.  Peyr.........................B1 Gossypium capitis-viridis Mauer...........................................B3 section Pseudopambak Prokhanov subsection Pseudopambak Gossypiumstocksii Mast. in Hook.........................................E1 Gossypium somalense (Gürke) J.B.Hutch...............................E2 Gossypium benadirense Mattei.............................................E Gossypium bricchettii Ulbrich...............................................E Gossypium incanum (Schwartz) Hillc.....................................E4 Gossypium areysianum Defl.................................................E3 subsection Longiloba Fryxell Gossypium longicalyx J.B.Hutch.  Lee ...................................F1 subgenus Karpas Gossypium hirsutum L.....................................................(AD)1 Gossypium barbadense..............................................(AD)2

7. 2. Distribution of species of Gossypium • Cultivated species growing wildly and primitive landraces are distributed throughout the tropical belt except for the high mountains. • They occupy more mesophytic up to very humid habitats.

8. Wild species of Gossypium are restricted in their distribution to the tropical belt between latitudes 200N and 250S. • They are confined to semidesert regions so that their distribution is disjunct with hyatus in Zaire and north Zambezian basins. • G. longicalyx and partly G. herbaceum ssp. africanum tend to occupy slightly more mesophytic habitats.

9. Phytochoria and mapping units after White (1983) in which African species of Gossypium occur. The Sahel regional transition zone: • 54a Sahel semidesert grassland and shrubland • 43 Sahel Acacia wooded grassland and Acacia deciduous bushland The Somalia-Masai regional center of endemism: • 54b Somalia-Masai semidesert grassland and shrubland • 42 Somalia-Masai Acacia-Commiphora deciduous bushland and thicket The Karoo-Namib regional center of endemism and transition to Kalahari: • 74 The Namib desert • 51 Bushy Karoo shrubland • 36 Transition from Colophospermum mopane scrub woodland to Karoo-Namib shrubland • 56 Kalahari/Karoo-Namib transition The Zambezian regional center of endemism • 28 Colophospermum mopane woodland and scrub woodland • 29 Zambezian undifferentiated woodlands

10. 2.2. The Somalia-Masai Regional Center of Endemism • 1. South-eastern distribution of . somalense • 2. Entire distribution of G. benadirense • 3. Entire distribution of G. bricchettii • 4. African distribution of G. stocksii • 5. African distribution of G. incanum • 6. Southern distribution of G. longicalyx • 7. Distribution of G. trifurcatum 2.5. Southern Arabia • 1. entire distribution of G. areysianum • 2. distribution of G. incanum • 3. part of the distribution of G. stocksii G. benadirense grows in Upper Giuba in Somalia and southern Ethiopia and in lower Uebi Scebelli on limestone rocks as G. somalense. G. bricchettiidistribution represents an eastern extension of area of G. somalense(northern Mudugh and south of the Nogal Valley, Somalia). No evidence of distribution are known from Ethiopia although it may grow in eastern Ogaden The sites were described as plains or limestone slopes overgrazed limestone-gypsum pavement with grey soil or around gypseous drainage hollows. The plant cover:Salvadorean, Acacia-Commiphora open bushland. Gillet, Hemming and Watson (#21941) reported widespread distribution in the western part of central Somalia.

11. G. longicalyx • The distribution seems to be disjunct. • Great Ruaha Valley, Tanzania. Only one specimen were collected ca 1900 km N in Meshra el Zeraf in Sudan. • reported mostly from Commiphora-Combretum zone between 700-900 m growing in open or closed bushland of Combretum sp, Terminaliastuhlmannii, Acacia nigrescnes and Delonix elata or from Acacia seyal-A. melifera community from the surroundings of Nondwa. It grows very local and uncommon. • The northern Sudan locality belongs to the Sudanian center of endemism, to the mapping unit 61, Edaphic grasslands of the Upper Nile basin (White, 1983). • It grows most likely on black clay soils where rainfall is about 750 mm (Knight 1949). • The collection has never been repeated since the Brown's (s.n., 1910) original one.

12. 3. Priority Regions for Collecting of Cotton Germplasm

13. Conclusions • Estimated species distribution was corrected by plotting of exact data • Distribution most of species matches with certain phytochoria/mapping units of Vegetation map of Africa • Some species are very restricted: • The distribution of G.longicalyx is restricted to a small area of central Tanzania and S Sudan • G.incanum occupies the coastal strip of S Yemen, one specimen was found in the Nogal Valley, Somalia (Hemming & Watson 3156, K) • The coincidence with veg. map suggests a possibility to predict their further distribution • The distribution of wild species is restricted mostly to arid habitats, which are generally endangered by desertification and overgrazing • The occurrance of species within the distribution area is rather rare or very rare

14. The distribution restricted species are known (have been collected) from a few or only one locality • Presence of G.incanum and G.longicalyx in germplasm collections is based on one sample only, others, if present, are duplications • The small species G.benadirense, G.bricchettii and G.trifurcatum are most likely not available in germplasm collections • There is a serious danger of extinction of all the distribution restricted species • Collecting of all African and Arabian species should be considered for ex situ conservation as an international priority • In situ conservation at least of restricted species should be considered if it is not late at all • A compiled vocabulary of vernacular cotton names should help in collecting

15. Acknowledgements • I would like thank to Dr.J.Trevor Williams, IPGRI • And to Drs. R.J.Kohel, P.A.Fryxell and A.E.Percival, USDA, SPA, College Station, TX