Karyological Races and Ecology of the Brazilian Duguetia furfuracea as Compared With Xylopia aromatica (Annonaceae)

Flora (1984) 175: 195-209

Karyological Races and Ecology of the Brazilian Duguetia furfuracea as Compared With Xylopia aromatica (A nnonaceae) WILFRIED MORAWETZ Institute of Botany, University of Vienna, Austria

Summary D. fufurcaea, a highly adapted pyrophyte of the Central Brazilian savanna vegetation contains three karyological races (2n = 16, 24, 32) which are to some extent geographically and ecologi. cally differentiated. The forest species D. cf. lanceolata and D. cf. salicifolia have chromosome numbers of 2n = 16. The triploid race of D. furfuracea is probably apomictic. X. aromatica (South Brazil to Cuba) has 2n = 16, identical chromosome numbers occur in X. emarginata (Central Brazil), X.ferruginea (Asia) and African members of the genus. A compar· ison between X. aromatica and D. furfuracea in regard to chromosomes, ecology, distribution areas, growth forms and systematics leads to the conclusion that the two Annonaceous species exhibit dissimilar differentiation pattcrns (disruptive in the D. furfuracea complex, more clina! in X. aromatica and allied taxa).

Introduction Whithin the poorly known speciation patterns of tropical woody plants the most frequently found syndrom is a± drastic eco-morphological differentiation on species or subspecies level whereas the chromosome number or even the nucleus structure keeps stable (e.g. Drimys: EHREXDORFER et al. 1979, Jacaranda: MORAWETZ 1982, Caryocar: MORA WETZ & DA WE 1984). Recently it has been proposed that the frequently cited karyological stability in tropical trees is more due to a laek of knowledge than to real circumstances (MORAWETZ 1984a). In this context, it seems interesting that D. furfuracea, a widespread Brazilian savanna shrub contains 3 karyological races which, however, are inseparable morphologically. The purpose of this paper is to analyse how far the different ploidy levels of D. furfuracea correspond to geographical distribution and ecology. For comparison another Annonaceous savanna plant, X. aromatica, was investigated. To get a better idea of the different evolutionary pathways of the two species, chromosome numbers of related taxa of both genera are also presented.

Material and Methods Karyology: ::\Ieristematic tissues were fixed in the field with "Carnoy" and stored for several years at -30 DC. Chromosome preparations were made according to the HCl/Giemsa method (GUERRA 1980, see also MORAWETZ 1981). The permanent slides are stored in the personal collec. tion of the author. For chromosome counts, several well.spread meta phasic to prometaphasic plates of each fixation were drawn with the aid of a camera lucida at a magnification of 9,400 x. In critical cases (tri. and tetraploid samples) vegetative (leaf buds) as well as generative (flower buds) material was investigated. Ecology: Observations on the ecology and phytosociology were made during several field trips in the years 1975-1981 travelling through Sao Paulo, Goyaz, Sergipe, Bahia and Amazonas. 13*

196

W.MORAWETZ

The dot map is based on personally seen specimens, field observations and the data of FRIES (1930, 1934). In D. furfuracea all seen specimens are cited, in the other species only the vouchers for chromosome counts. The numbers in front of the cited specimens refer to the text. Herbarium material came from the Herbaria Berlin (B), Kew (K), Munich (M), Utrecht (U) and Yienna CWU). DU[Juetia furfuracea (ST. HIL.) BENTH. & HOOK. Paraguay: (I) Zwischen Rio Apa und Rio Aquidaban, 1908/9, FIE BRIG 4422 (M); (2) in regione superioris fluminis Apa, XII. 1901/2, HASSLER 8138 (K); (3) Sierra de Amambay, XII. 1970/8, ROJAS 9796 (K); (4) Dep. San Pedro, Distr. San Estanislau, 13. II. 1975, PEDERSEN 76 (K.) Brazil: Parana: (5) Campo murao, Cerrado, 8. XII. 1965, HATSCHBACH et a!. 13276 (U); (6) :\'[un. Sengas, Rio do Funil, 13. XII. 1958, HATSCHB. 5272; (7) S of Rio Nai, 15 km E of Sao Tome, 240 m, 5. IV. 1966, LINDEMANN & DE HAAS 894 (K, U). Sao Paulo: Mun. Botucatu, (8) 18 km N of Botu., 14 km E of Sao Manuel, Cerrado, 550 m, 25. II. 1971, GOTTSBERGER 21 R/no. 1 (WU); (9) - 23. VIII. 1973, GOTTSBERGER & EHRENDORFER 73823 8-18 (WU); (10) on the way from Botucatu to Pardinho, disturbed Cerrado, ca. 900 m, 6. I. 1981, MORAWETZ 11-6181 (WU). ::\Iato Grosso: (Il) 270 km N of Xavantina, 12° 54' S, 51° 22 "V, Cerrado, 10.3.1968, GIFFORD G 79 (K); (12) 260 km NNE ofXavantina, 12°51' S, 51° 45' V\T, Cerrado, 450 m, 27. V. 1968, GOTTSBERGER 11-27568 (WU); (13) Xav. 14° 38' S, 52° 14' Cerrado, 25. IX. 1967, ARGENT et a!. 6525 (K); (14) 2 km N of Xav., Cerrado, 500 m, 19. VIII. 1967, RATTER et a!. 384 (K); (15) Cuiaba, )Iun. Sto. Antonio de Lererger, 15° 41' S, 56° 18' W, Cerrado, 140 m, 31. I. 1978, EHREXDORFER 78131-1803 (,,'U); (16) Cuiaba, Chapada dos Guimaraes, Cerra do 13. X. 1973, PRAXCE et a!. 18891 (U); (17) SE of CuiaM, Campo Grande, IV. 1949, HANKE 28 (U); (18) Garapu, 13°12'S, 52°34'W, Cerrado, 300-400 m, 30. IX. 1964, IRWIN & SODERsTRmI 6491 (B, K, 1\1). Goias: Serra do Caiap6, (19) 60 km S of Caiaponia on road to Jatai, Cerrado, 800-1000 m, 27. X. 1964, IRWIX & SODERSTROM 7431 (K, U); (20) -,12 km S of Caiaponia, Cerrado, 860 m, 30_ IV. 1973, AXDERSON 9493 (U); Serra dos Cristais, (21) - Cerrado, 1175 m, 5. XI. 1965, IRWIK et a!. 9952 (K); (22) - , 12 km N of Cristalina, Cerrado, 1060 m, 3. IV. 1973, AKDERSON 8025 (U); (23) - , on the way from Luziania to Cristalina, km 38, Cerrado, 1000 m, 13. XII. 1980, MORAWETZ 12I:H280 (WU); (24) - , next to Cristalina, Campo rupestre on rocky ground, 1200 m, 14. XII. 1980, )[ORAWETZ 21-141280 (WU). Minas Gerais: Serra do Espinha<;o, (25) - , rocky sandstone hillcrops, 1080 m, 2. II. 1972, AKDERSOK et a!. 35139 (U); (26) - , rocky slope near gallery forest, 10.IY. 1973, AXDERSOK 8585 (U); (27) - , 28 km SV\T of Diamantina, grassy meadow and sandy campo, 1300 m, 15. I. 1969, IRWIK et a!. 22017 (U); (28) - , vicinity of Datas, 24. I. 1969, IRWIN et al. 22572 (U); (29) - , 30 km NE of Francisco Sa, Chapada with Cerrado, 1100 m, 10. II. 1969, IRWIX et al. 22954 (U); (30) - , Cerrado, 1000 m, 23. Feb. 1969, IRWIN et a!. 23699 (U); (31) - , 25 km E of Diamantina, 800 m, 15. III. 1970, IRWIN et a1. 27569 (U); (32) - , Cerrae!o on brown sane! with occasional outcrops, 1150 m, 27. III. 1970, IRWIX et a!. 28427 (U); (33) BR-4, entre tres )Iarias e Joao Pinhero, 26. III. 1963, PEREIRA 7313 (B); (34) Congonhas do Campo, 1887, SCHEXCK 3498 (B); (35) Uberaba, open Cerrado, 9. V. 1966, GOODLAND 324 (U); (36) 5 km NE of Rio Manso and Couto de Magalhaes, Cerrado, clay soil, 960-1000 m, 13. IV. 1973, A:-WERSOK 8737 (U); (37) Rio Bicudo, 20 km W of Corinto, 525 m, :3. III. 1970, IRWIN et a1. 26817 (U); (38) 2 km N\Y of Paracatu, Cerrado, 700 m, 7. II. 1970, IRWIK et al. 26312 (U); (39) )Iun. de Prata, 19. III. 1963, MAGALHAES 52 (U.) Bahia: Serra do Sincora, (40) - , 133 km N of Cascavel on the toad to Mucuge, Campo geral, 1200 m, 25. III. 1980, HARLEY 20960 (K); (41) - , 15-20 km from Andorai, secondary very dense mixed forest, 500-600 m, 13. II. 1977, HARLEY 18634 (K, U); (42) Chapadao Ocidental da Bahia, Ca. 15 km S'Y of Correntina, Cerrado on sand, 600 m, 25. IV. 1980, HARLEY 21742 (K); Serra do Tombador, low woodland, base of Morro do Chapeu, 1100 m, (43) -,18. II. 1971, IRWIN et a1. 32471 (U); (44) - , 21. II. 1981, MORAWETZ 11-21281 (WU); (45) Espigiio Mestre, 23 km W of Barreiras, rocky Cerrado and Cerradao, 680 m, 3. III. 1972, ANDERSON et a1. 36544 (U); (46) Rio das Ondras, 5 km NW of Barreiras, Cerrado, 650 m, 4. III. 1971, IRWIN et al. 31496 (U); (47) Lagoinha, 5,5 km SW of Delfino, 950-1000 m, 4. III. 1974, HARLEY et a1. 16717 (K, M, U); (48) Serra das Almas, 25 km WNN of Vila Rio de Contas, disturbed ground among cultivation, 1400m, 20. III. 1977, HARLEY 19748 (K, U); (49) Vit6ria da Conquista, 900 m, 4. III. 1978, MORl et a!. 9437 (U); (50) Serra da Agua de Rega, 23 km N of Seabra, Cerrado, 24. II. 1971, IRWIN et al. 30914 (U). Ceara: (51) Araripe, Agreste queimado, LUETZELBURG 26135 (M).

"T,

K,tryological Races and Ecology

197

Duguetia cf. l(["ceolata ST. HIL. Brazil: (52) Sao Paulo, 60 km SE of Sao Paulo, Paranapiacaba, mountain rain forest, 800~900 m, 25.~27. VIII. 19n, EHRENDORFER & GOTTSBERGER 7382513-8(WU). Duguetia cf. salicifolia R. E. FR. Brazil: (53) Sao Paulo, Paranapiacaba, 25.~27. VIII. 19n, EHREXD.& GOTTSB. 73825-13-42 (WU). Xylopia aromatica (LAM.) :\IART. Brazil: Sao Paulo: (54) :\Iun. de Botucatu, 18 km N of Botu., 14 km E of Sao :\Ianuel, Cerrado, 550 m, 23. VIII. 197:3, EHRENDORFER & GOTTSBERGER 738238-7 (WU); Goias: (55) N of Cristalina, Cerrado, 1 170 m, 12. XII. 1980, MORAWETZ 21-121280 (WU); Sergipe: (56) BR-101, 20 km S of Rio Sao Francisco, 10. III. 1981, MORAWETZ 11-10381 (VVU); Amazonas: (57) Manaus, Ponta Negra, 22. X. 1974, EHRENDORFER 740922-0215 ('VU); (58) Rio ~egro, 28. X. 1974, EHRENDORFER 740928-0102 (WU). Venezuela: (59) Guyanas, Canaima, 8. X. 1974, EHRENDORFER 741008-0102 (WU). Xylopia emarginata MART. Brazil: Brasilia D. F.: (60) 9. V. 1974, EHRENDORFER 74592-9 (WU). X. ferruginea (HK. f. & THm!s.) HK. f. & THOMS.: (61) Singapore, 18. VII. 1981. EHREKDORFER 8171802-04 (WU).

Karyology Both genera have the same base number x = 8 (see Table 1). In Duguetia these are the first chromosome counts of the genus; in Xylopia the here presented numbers from America (X. aromatica, first count for X. emarginata) correspond with previous counts from Cuba (X. aromatica, LEPPER 1979) and those from Africa (X. rubescens OLIV., X. staudtii ENGL. & DIELS; MANGE NOT & MANGENOT 1962) and Asia (X. jerruginea, first count). The general morphology of metaphasic chromosomes in both genera fits very well into the karyological syndrom of most A nnonaceae (MORAWETZ 1984b): The 2n karyotype shows one big pair of chromosomes and seven smaller ones of decreasing length which are subtelocentric to metacentric. Though a detailed analysis of karyotypes from field fixations is problematic, a main difference between the karyotypes of the two genera became obvious: The chromosomes and satellites of the first pair in Duguetia speceis are much bigger than in the Xylopia species investigated (Figs. 1,2). In X. aromatica, samples of several neotropicallocalities had the constant number 2n = 16 (Table 1). In D. jurjuracea, only specimens from the NW region of the distribution area were on the diploid level (Fig. 4), two plants from distant localities in the South were on the triploid level (2n = 24) and the Central to NE-Brazilian plants showed tetraploid somatic chromosome numbers with 2n = 32. A comparison of the

Table 1. Chromosome numbers of Duguetir{ and Xylopia (voucher numbers refer to :Material and Methods) Species

2n

vaucher number or reference

Duguetia cf. lanceolrtta D. cf. salicifolia D. furfuracea D·furfuracea D. furfuracea Xylopia emarginata X. aromatica

16 16 16 24 32 16 16

X. ferruginea

16

52 53 12, 15 9, 10 23,24,44 60 LEPPER 1979, 54,55,56,57,58,59 61

198

,Yo

l\IORAWETZ

different ploidy levels (Figs. 2 cd, 3) suggests that the polyploidisation occurred without major structural changes of the meta phasic chromosomes: The haploid chromosome set is similar in length and centromere position to the lx-karyotype of the tri-and tetraploid races. Ecology D. furfuracea is a typical pyrophyte, highly adapted to the Central Brazilian savannas. It is a small (max. 1.5 m high) shrub with several thin stems which sprout

from a well developed, thick and elongate xylopodium (Figs. 5, 6, 7). This underground organ is usually much longer than the stems. The frequent and in former times naturally occurring burning of the vegetation destroys the aerial parts of the plant completely, new sprouts come from the top of the xylopodium near the ground surface or beneath. Without fire the thin stems die after a certain period and regenerate from the base.

,

a

:t. t c

Fig. 1. Different ploidy levels in D. furfuracea. a somatic meta phasic chromosomes of a diploid (2n = 16) plant from Cuiaba (15); b prometaphasic chromosomes of a tetraploid (2n = 32) individual from Bahia (Morro do Chapeu 44); c meta phasic triploid nucleus (2n = 24) from the Botucatu population (9). Bar: 10 ftm.

Karyological Raees and Ecology

199

Because of its long xylopodium and root system D. turturacea is mostly restricted to deep soils such as in typical Cerrado regions of Central Brazil; however, on a more rocky ground-like in the Campos rupestres (e.g. Cristalina 24)-it roots in clefts of rocks or reduces its xylopodium to a minimum. D. turturacea flowers throughout the year without any synchronisation within the population. In most cases fruiting, flowering and sterile individuals can be found close together.

a

b

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c

0\f 0D~~~;?;j@~~~&l~~@ fl\t ~1~QDl~~12J8ID£IO BIO 2)1

e

Fig. 2. Karyotypes of meta to prometaphasic·· chromosomes in Duguetia and Xylopia species with 2n = 16. a-b D. cf. salicifolia from the coastal rain forests (53); c-d D. furfuracea (15); e-f X. aromatica (54). The chromosomes are paired according to their probable homology; note the difference in the first pair between the Duguetia species and X. aromatica. Bar: 5 pm.

I

I

-~.---

-

---

Fig. 3. Karyotypes of trio and tetraploid somatic chromosome sets in D. furfuracea. a-b the southern Pardinho population with 2n = 24 (10); c a plant from Bahia (44), and d an individual from Goias (24), with 2n = 32. The karyotypes are arranged in groups of 3 (a-b) and 4 (c-d)morphologically similar chromosomes. Bar: 10 pm.

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8

Kal'yological Ra('es and E('ology

Within the dense arboreolls Cerrado vegetation D. turturacea plays a less important role in the shrub layer and is somewhat better represented in the open grassy to shrubby Campos. The frequenee is low; either single individuals or groups of 3-lO plants were found. The different karyological raees show a certain divergence in regard to ecology and phytosoeiology. The site descriptions presented here are based on own observations and literature. Both D. turturacea populations with 2n = 16 Occur in the western Cerrado region adjacent to the Amazonian forest (Xavantina: 12, Cuiaba: 15). Cerrado is the most typical Central Brazilian savanna vegetation type, mainly characterized by tortuous

Fig. 4. Geographical distribution of D. furfuracea (dots) and X. aromatica (circles). Arrows point to cytologically investigated D. furfuracea and X. aromaticrt (small and large arrows, respectively). Based on Flora Xeotropica base map no 1 jUniv. of Utrecht.

202

W. MORAWETZ

trees with thick barks, hard and brittle leaves, a characteristic flora composition of mainly woody plants, deep soils and regularly occurring fires (EITEN 1972). Well analysed are the different Cerrado types of the Xavantina region (RATTER et al. 1973) where D. furfuracea was found sympatrically with following typical Cerrado species (a complete list in RATTER et al. 1973): Annona coriacea (Annonaceae) ,

Brosimum gaudichaudii (M oraceae) , Caryocar brasiliense (Caryocaraceae), Casearia silvestris (Flacourtiaceae) , Erythroxylum suberosum (Erythroxylaceae) , Hancornia speciosa (Apocynaceae), Palicourea rigida (Rubiaceae), Qualea grandiflora, Qu. multiflora, Salvertia convallariodora (Vochysiaceae), Tocoyena formosa (Rubiaceae) , Roupala montana (Proteaceae), Xylopia aromatica (Annonaceae).

1 '\

Fig. 5. Vegetation profile 11 x 3 m of a Campo Cerrado in the Serra dos Cristais (km 38 road Brasilia·Cristalina), 1000 m with Duguetia furfuracea (Du.) An = Annona tomen/osa R. E. FR., Jr = Jacaranda rufa }IAsso, Ju = J. ulei BrR. & K. SCHUM., Ki = Kielmeym'a sp., Le = Leguminosae, }Ii = Mimosa sp., 8m = Smilax sp., So = Solanum sp., To = Tocoyena formosa SCHL-M.; furtllt'r spt'cie~ occurring next to this area are Caryocar brasiliense CAMB., Dimorphandra mollis BEXTH., Erythroxylum suberosum ST. HIL., Ouratea sp., Qualea grandiflora MART.; in a certain distanC'e was also found Xylopia aromatica (LAM.) }fART.

Fig. 6. Growth forms. a D. furfuracea near Brasilia (23), note the thick underground xylopodium and the thin at'rial stemlets b X. aromatica from Sergipe (56), a treelet with drooping side branches.

Karyological Races and Eeology

203

Most of these species also occur in the Southern Botucatu and Pardinho sites with D. furfuracea (2n = 24; 9, 10) and the Central Brazilian Cristalina-Luziana region (2n = 32; 23, 24) but differ completely from the Bahia site Morro do Chapeu (2n = 32; 43). Some of the differentiating species from Xavantina to the Botucatu area (and probably Morro do Chapeu) are: Callisthene fasciculata (Vochysiaceae), Cordia insignis (Boraginaceae) , Curatella americana (Dilleniaceae) , K ielmeyera rubriflora (Clusiaceae) , Ouratea nana (Ochnaceae) , Physocalymma scaberrimum (Lythraceae) , Siparuna guinanensis (Siparunaceae), Virola sebifera (M yristicaceae), Xylopia sericea ( Annonaceae). The Cuiaba site with D. furfuracea (2n = 16; 15) represents also an open Cerrado formation, in which several species are identical to the previous site (e.g. Curatella americana, Hancornia speciosa, Tocoyena formosa); a characteristic species, not found in any of the other investigated areas, is Jacaranda cuspidifolia.

Fig. 7. D. furfuracea. a complete plant with fruit (arrow) next to Pardinho (10, 2n = 24); note the thick excavated xylopodium and the thin aerial stems; bar: 50 em. b detail from the upper part of the xylopodium (Serra dos Cristais, 24, 2 n = 32) showing the probable sequence of sprouting; 1,2 = eldest stems, both burnt down, 3 = flowering stem, 4 = younger sterile stem, still growing, 5 = sleeping buds; bar: 5 em.

20+

\V.

:\IoRAWETZ

In the Botucatu-Pardinho region D. furfuracea (2n = 24; 9,10) is an occasional member of different Cerra do types (Cerrado, Campo cerrado, Campo sujo) which are in structure somewhat similar to those of Xavantina (compare vegetation profiles in RATTER et al. 1973 and MORAWETZ 1982). A floristic analysis is given in SILBERBAUER-GOTTS BERGER et al. (1977), differentiating species to the northern Cerrados are not so frequent as vice versa because the Cerrado flora is relatively poor. A typical southern Cerrado species is Jacaranda oxyphylla. The region of Brasilia where D. furfuracea (2n = 32; 23,24) occurs sometimes in Cerrados (Fig. 5) similar to the areas described above already leads to ecologically completely different habitats: D. furfuracea inhabitats low and rocky Campos rupestres and grows with various Velloziaceae and some small leaved subshrubs. Entirely different vegetation types and species compositions are found in Bahia where the 2n = 32 race of D. furfuracea occurs. E.g. at the Morro do Chapeu (43) it was found in Campos gerais, a low shrub- and woodland, mainly characterized by the absence of typical features of the Campos Cerrados and rupestres. Some characteristic species are Jacaranda irwinii, Casearia eichleriana, Byrsonima gardnerana, B. vaccinifolia, furthermore several Hyptis, Eriope and Cassia species (HARLEY & MAYO 1980), none of which occur in the other sites. Records for D. furfuracea are also available from the Serra do Rio de Contas where it was found in a cut over woodland together with Caryocar brasiliense, Terminalia fagifolia (Combretaceae) , Evolvolus pterocaulon (Convolvulaceae) , Byrsonima correifolia, B. sericea, Qualea dichotoma and others (HARLEY & MAYO 1980). In the Cerra do of the Serra de Cural feio Duguetia is sympatric with Byrsonima triopterifolia, B. vaccinifolia, Eriope latifolia, E. tumidicaulis, Evolvolus glomeratus, Humiria balsamifera (Humiriaceae). Krameria tomentosa (Krameriaceae), Mandevilla tenuifolia (Apocynaceae), Schultesia pachyphylla (Gentianaceae). In the Serra do Sincora D. furfuracea occurs in the shrub layer of a dense secondary forest together with Allamanda oenotherifolia (Apocynaceae) , Cordia curassavica, Erythroxylum betulaceum, H ymenaea stigonocarpa (Caesalpiniaceae) and others (HARLEY & MAYO 1980). Most of these taxa are typical for the NE dry areas and show the differences in species composition to the Cerra do and Campo rupestre areas. Xylopia aromatica is a typical and frequent tree of various savanna types in the Neotropics but penetrates also in low forests and occurs in the humid zones at river banks. Like most Cerra do plants it flowers already as a small treelet and may under good conditions reach heights of several meters; in forests it is said to grow up to 15111. It has no special adaptations to fire comparable to those of D. furfuracea but the relatively thin bark seems to be fire-resistant and after burning it sprouts from the branches and the main trunk; it is only when the trunk is destroyed completely (e.g. after frost in the South, SILBERBAUER-GOTTSBERGER et al. 1977) that the new buds come from the base near the ground surface. The growth form of X, aromatica is characterized by a single relatively thin orthotropous main trunk and several spreading to ± drooping side branches; branches of the second order and distichous leaves often tend to be arranged in the same plain (Fig. 6). Flowering, mostly population synchronized, occurs once a year and may differ somewhat from region to region. The most frequent period (observed in Goyaz, Minas Gerais and Sergipe) is December to February. At least in the observed Cerra do regions, X. aromatica is an important member of the shrub ad tree layer, often building up large populations. In the Central Brazilian Cerrados it is often sympatric with D. furfuracea (see previous descriptions) but it normally does not occur in Campos rupestres and in the dry NW-Brazilian areas

Karyological Races and Ecology

205

such as Bahia. Because of its more extensive distribution range (Fig. 4) it is frequently found in vegetation types completely different from the Central Brazilian Campos in regard to structure and phytosociology. Only two examples shall be mentioned here. In an open Amazonian savanna near Humaita it was found as one of several scattered tree species within a dense grassland together with Byrsonima linguifera, Curatella americana, Cordia bicolor, C. hispidissima, Desmoncus sp. (Arecaceae) , Palicourea rigida, Physocalymma scaberrimum, Orbignya speciosa (Arecaceae) , Salvertia convallariodora, Tetragastris unifoliata (Burseraceae) and others (GOTTS BERGER & MORAWETZ, in prep.). In complete contrast is its occurence in Cuba (Isla de Pinos) where X. aromatica is a member of a tropical light Pine forest and grows with Byrsonima crassifolia, B. wrightiana, Davilla rugosa (Dilleniaceae) , Ouratea elliptica, Pinus tropicalis, and Tabebuia lepidophylla (Bignoniaceae); a complete list in SCHUBERT et al. (1979).

Discussion D. furfuracea and X. aromatica have much in common: Both are typical Annonaceous savanna plants of Central Brazil and often occur sympatrically; both are capable to survive fire and have many similarities in floral biology (GOTTSBERGER 1970). They, furthermore, have the same chromosomal base number x = 8 and are the only wide spread Campos species of the two genera. Most of their parents occur in the (rain-) forest. Nevertheless, the numerous biological-ecological differences (Table 2) indicate two completely distinct pathways of evolution within the investigated taxa. Karyology. The most interesting aspect in D. furfuracea is the intraspecific differentiation into diploid, triploid and tetraploid races. For South America this is the first record in woody plants, in Africa Diospyros lycioides, for example, shows different ploidy levels (WHITE & VOSA 1980). However, similar cases of this poorly studied phenomen are expected to be more frequent (MORAWETZ 1984a). The different Table 2.

~Iorphological

-

biological differences between D. Jw:furacea and X. aromatica

Occurrence

Distribution range Growth form Underground organs Leaf bearing branches Leaf arrangement Stem without burning Stem after burning Regeneration Flowers and fruits Flowering Dispersal syndrome 2n chromosome number

D. JurJuracea

X. aromatica

Campos Cerrados Campos rupestres Campos gerais limited, Paraguay to Central-NE-Brazil shrub, up to 15 m

most neotropical Savanna-types, forests, river-banks extensive, almost whole Neotropics treelet to tree, up to 5 (8-15) m roots plagiotropous distichously long-lived alive from buds on stems and branches erect ± synchronous mammaliochorous 16

xylopodium orthotropous spirally short-lived dead from upper part of xylopodium hanging asynchronous ornithochorous 16,24,32

206

\v.

::\IoRAwETz

ploidy levels correlate with the geographical distribution (Fig. 4): The 2n = 16 plants are restricted to the NW of the area, the triploid race occurs in the south and the tetraploid individuals go from the centre to the NE. Triploid woody species so far only have been recorded from Dipterocarpaceae in Asia which are said to be apomictic (KAUR et al. 1978). The triploid individuals of D. jurjuracea apparentely propagate by seeds (ripe fruits seen, no vegetative propagations, e.g. 10). This also may indicate apomixis, which is said to be not too rare in tropical habitats (KAUR et al. 1978) Embryological and meiotic studies of these triploid Duguetia populations are certainly in need. X. aromatica in contrast has in all investigated populations from S-Brazil to Cuba the same chromosome number 2n = 16, which indicates a karyological stability within the whole distribution area. Ecological radiation. The karyological races of D. jurjuracea correlate relatively well with the distinct ecological positions within the savanna vegetation of Brazil. The western 2n = 16 race occupies species-rich Campos Cerrados adjacent to the S-Amazonian forest sometimes transitional to dense dry forests or Cerradaoes or open shrubby Campos limpos (RATTER et a1. 1973). The southern localities with the 2n = 24 race differ not so much in structure but in species composition and climate (much cooler, sometimes frost: SILBERBAUER-GOTTSBERGER et al. 197i). Here we are already near to the southern limit of the typical Campos Cerrados which occur only in relatively small patches. The 2n = 32 race is frequent in Cerrados ± similar to those of the western part; from here D. jurjuracea penetrates into the structural completely different Campos rupestres (EITEN 1978), a low and shrubby vegetation type on rocky soils. From these extreme habitats with a very peculiar flora and vegetation structure the tetraploid race extends into the Bahian area in the NE where it is found in dry forests, Campos gerais and some Bahian Cerrado types. Most of this localities are characterized by a specific flora and a much drier climate than the Southern and Western investigated sites. The eco-karyological differentiation of D. jurjuracea may be comparable to the eco-systematic species differentiation in Jacaranda which, however, has throughout the genus the same chromosome number (MORAWETZ 1982). In the 2n = 16 area of D. jurjuracea we find J. cuspidijolia and J. brasiliana - Cerra do tree as well as J. decurrens and J. ruja - two small xylopodium shrubs: in the southern 2n = 24 area remain only J. decurrens and J. ruja, a further sympatric taxon restricted to this area is J. oxyphylla, parapatric is the SE centered forest species J. micrantha. In the western part of the 2n = 32 area of D. jurjuracea (Brasilia) there are still some species of the 2 n = 16 localities (J. brasiliana, J. ruja) , sympatric species which indicate a connection to the Bahian area are the NW-centered J. ulei and a population of an Jacaranda species closely related to J. irwinii. The Bahian site (Morro do Chapeu) is characterized by the typical NE centered species J. irwinii, which is sympatric with Duguetia. Similar differentiation patterns could be drawn in several different genera as Annona (Annonaceae), Byrsonima (Malpighiaceae) , Kielmeyera (Clusiaceae),Ouratea (Ochnaceae) and Qualea (Vochysiaceae). On the other hand X. aromatica occupies not only most of the D. jurjuracea sites (exept in Bahia) but also a wide range of different sa vanna and forest types throughout the Neotropics (e.g. Aamazonian wet savannas, Columbian highland savannas, river banks in the Amazon region, dry forests, pine forests in Cuba etc.). Thus X. aromatica, 2n = 16 in all investigated localities, exhibits a far wider ecological amplitude than D. jurjuracea and may be compared with the ± similar wide spread Savanna tree Cura/ella americana (KUBITZKI 1971).

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Chorology. The distribution range of D. turturacea (Fig. 4) is largely confined to areas of Campos Cerrados and - rupestres, i.e. it is mainly dependend on soil composition and less on climatic factors (ARENS 1963). Consequently its distribution range is undisrupted in Central Brazil and consists of several scattered disjunct parts on the margins (e.g. S-Brazil) where only small patches of Cerrado occur amidst large forest areas. Several non-Cerrado areas in the NE probably have a ± similar soilclimate relation. The inhabited area of D. turturacea is relatively extensive as compared to other Campos-species, which usually have more limited distributions in the Cerrado areas (EITEN 1972; MORAWETZ 1982). The most frequent medium- to small-sized distribution areas of Cerrado plants would correlate better with the geographically distinct karyological races of D.

turturacea. Xylopia aromatica has a high degree of tolerance as regards soils and climate and, thus, it occupies a very large area, which is mainly limited by the tropics. Nevertheless the local distribution is regulated by its preference for mesic to slightly dry, sun-exposed sites. Consequently it is absent from extreme dry areas like NEBrazil (except near the coast, e.g. 56); in humid areas, it grows on well drained sandy soils (river banks) or in open places like margins of savannas. It mostly avoids dense high forests but is frequent in light or open low woodlands. Growth forms. The two investigated species differ strongly in their growth form (Fig. 6). D. turturacea has the majority of its biomass subterraneous, building up a large xylopodium (Fig. 7). The aerial stems are thin and sprouting from buds near the ground surface. This shrubby growth- and life-form is typical for many other fire adapted Cerrado plants such as Jacaranda oxyphylla (MORAWETZ 1982), Annona tomentosa (Fig. 5) or Salacia campestris (RIZZINI & HERINGER 1962). Due to the short lived stems and branches the modification rate is very low: As opposed to some other xylopodious Cerrado plants, whose growth form may vary from a flowering shrub to a big tree, it never developes into a treelet or tree. X. aromatica has a growth form (Fig. 6) which is, on one hand, adapted to Cerrado conditions (flowering as a small treelet or shrub); on the other hand it can reach heights of several meters and may be compared with forest species of different members of Annonaceae or Myristicaceae. E.g. Annona cacans from the forests of S-Brazil has an erect main trunk and lateral dominant spreading to ± drooping side branches; Virola oleitera, a big forest tree of the SE Brazilian Serra do Mar has a similar growth form with distichous leaf-arrangement. Because of an extreme modification of growthheight X. aromatica may occur from low shrubby Campos to relatively high forests. E v 0 I uti 0 n. D. turturacea has its nearest related forest species in the Peruvian Amazon: D. odorata, a tree of about 10 m height (FRIES 1934), which probably has the chromosome number 2n = 16 like the other forest species D. ct. lanceolata and D. ct. salicitolia (Table 1). This region is geographically next to the most primitive D. turturacea race (2n = 16) in the Campos Cerrados adjacent to the Amazonian forest (Fig. 4). The evolutionary step forest tree ~ specialized Campos shrub (without existing intermediate forms) has occurred in many families (e.g. Jacaranda glabra a forest tree in the Peruvian Amazon, - J. ruta a small shrub of the Campos in Brazil; MORAWETZ 1982); it indicates disruptive selection. This differentiation pattern apparently has been maintained in D. turturacea: The different karyological races linked with an eco-geographical specialization indicate a further beginning disruptive speciation. However, the lack of morphological variation (flowers, leaves, epidermis ultrastructure checked) does not allow a further taxonomic division at this stage. A interesting problem concerns the related savanna species D. hemmendortfii (from

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Sao Paulo) and D. jonasiana (from Mato Grosso): It still needs to be proven if they originated from the southern 2n = 24 or the western 2n = 16 race of D. furfuracea. Xylopia arornatica has its nearest allies in X. nitida and X.longifolia in the Guyanaforests (FRIES 1930). The latter is sometimes difficult to distinguish from X. arornatica and differs only in a few ± stable characters, it may be conspecific. This and some biological factors (growth form and height, synchronized flowering time) indicate that X. arornatica is much more closely allied to the forest species than D. furfuracea (Cerrado typical growth form and flowering time). The evolution from forest to savanna taxa has apparently occurred in small steps and ended in the highly variable species X. arornatica. For this reason, it may be argued that evolution within the X. arornatica complex is a more clinal than a disruptive one.

Acknowledgements I am grateful to Prof. Dr. F. EHRENDORFER and Prof. Dr. G. GOTTSBERGER for continuous interest and kind material support. This study has been supported by the "Fonds zur Forderung der wissenschaftlichen Forschung in Ostcrreich" (Project Nr. 4052 and 4799).

References ARENS, K. (1963): As plantas lenhosas dos Campos Cerrados como flora adapt ada as deficiencias minerais do solo. In: FERRI, :\1. G. (Ed.): Simp6sio sobre 0 Cerrado, Reprint 1971. Sao Paulo: Blucher. EHRENDORFER, F., SILBERBAUER·GOTTSBERGER, I., & GOTTSBERGER, G. (1979): Variation on the population, racial and species level in the primitive relic angiosperm genus Drimys (Winteraceae) in South America. PI. Syst. Evo!. 132: 53-83. EITEN, G. (1972): The Cerra do vegetation of Brazil. The Botanical rcview 38: 201-341, New York. - (1978): Delimitation of the Cerrado concept. Vegetatio 36: 169-178. FRIES, R. E. (1930): Revision der Arten einiger Annonaceen-Gattungen. Acta Hort. Berg. 10: 86-124. - (1934): Revision der Arten einiger Annonaccen-Gattungen. Acta Hort. Berg. 12: 28-105. GOTTSBERGER, G. (1970): Beitrage zur Biologie von Annonacccn-Bliiten. Osterr. Bot. Z. 1I8: 237-279. GUERRA FILHO, :\L (1980): Karyosystematik und Evolution der Rutaceae. Diss. Phil. Fak. Univ. Wien. HARLEY, R. M., & MAYO, S. J. (1980): Towards a checklist of the flora of Bahia. Royal Botanic Gardens, Kew, England, 250 pp. KAUR, A., HA, C. 0., JONG, K., SANDS, V. E., CHAN, H. T., SOEPADMO, E., & ASHTON, P. S. (1978): Apomixis may be widespread among trees of the climax rain forest. Nature 271: 440 to 442. KUBITZKI, K. (1971): Doliocarpus, Davilla und verwandte Gattungen (Dilleniaceae). Mitt. Bot. Munchen 9: 1-105. LEPPER, L. (1979): Beitrage zur Chromosomen-Dokumentation cubanischer Pflanzensippen 1. I Wissenschaftliche Z., Math.-Naturw. Reihe, Friedrich-Schiller-Universitat Jena 28. :\IANGENOT, S., & MANGENOT, G. (1962): Enquete sur les nombres chromosorniques dans une collection d'especes tropicales. Rev. Cyt. Bio!. Veg. 25: 411-447. MORAwETz, W. (1981): Karyologie und okologisch-morphologische Differenzierung von Peumus boldus (Monimiaceae, Laurales). Pl. Syst. Evo!. 138: 157-173. (1982): Morphologisch-okologische Differenzierung, Biologie, Systematik und Evolution der neotropischen Gattung Jacaranda (Bignoniaceae). Osterr. Akademie der Wissenschaften, Math. Naturw. Klasse, Denkschriften 123, 184 pp. (1984a): How stable are genomes of tropical woody plants? Heterozygosity of C-Bands in Porcelia as compared with Annona (Annonaceae) and Drimys (Winteraceae). PI. Syst. Evo!. 145 (in press).

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(1984b): Genome length and karyotypes in Annonaceae. PI. Syst. Evol. (in press). DAWE, J. (1984): First chromosome counts and systematics in the neotropical plant families Brunelliaceae and Caryocaraceae. PI. Syst. Evol. (in press). RATTER, J. A., RICHARDS, P. W., ARGENT, G., & GIFFORD, D. R. (1973): Observations on the vegetation of northeastern Mato Grosso 1. The woody vegetation types of the Xavantina-Cachimbo Expedition area. Philos. Trans, Ser. B 266: 449-492, London. RIzzrsI, C. T., & HERIXGER, E. P. (1962): Studies on the underground organs of trees and shrubs from some southern Brazilian Savannas. An. Acad. Brasil. Ci. 34: 235-247. SCHlCBERT, R., HELMECKE, K., KRlCSE, J., DEL RISCO, E., CAPOTE, R., VANDAMA, R., OVIEDO, R., VILAMAJO, E., & MEXEXDEZ, L. (1979): Ergebnisse der Expedition von Wissenschaftlern der Akadmie der \Vissenschaften Kubas und der DDR zur Isla de Pinos (Kuba) 1975. II. Ergebnisse geobotanischer Untersuchungen in den Pinares von Banos termales del Rosario und Lorna la Canada. Fedd. Repert. 90: 19-50. SILBERBAlCER-GOTTSBERGER, 1., ::\
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