Morphometric variations among three populations of the endemic Behria tenuzjlora (Aiiiaceae) in Baja Califomia Sur, Mexico

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Journal of Arid Environmenrs (1 995) 31: 77-8 1 Morphometric variations among three populations of the endemic Behria tenuzjlora (Aiiiaceae) in Baja Califomia Sur, Mexico Heidi Romero-Schmidt,

1 Journal of Arid Environmenrs (1 995) 31: Morphometric variations among three populations of the endemic Behria tenuzjlora (Aiiiaceae) in Baja Califomia Sur, Mexico Heidi Romero-Schmidt, Raymundo Domínguez Cadena & Alfredo Ortega-Rubio Centro de Investigaciones Biológicas del Noroeste S.C. Apdo. Postal No La Paz, 23000, BCS. México (Received 1 1 November 1993, accepted 26 Februa y 1994) Analysing 14 morphometric characteristics of individuals from three populations of Behria tenuzj7ora, a monospecific endemic genus of the Cape Region of Baja California Sur, México, enough statistical differences were found to conclude that there exists a subspeciation process leading, to at least two ecotypes, one in the arid zones, and the other in the conifer forest Academic Press Limited Keywords: arid zones; Baja California Sur; Behria tenuiflora; conifer forest; ecotypes; México; subspeciation; desert; sarcocaulescent scrub Introduction Behria tenuiflora Greene (Alliaceae) is a monospecific and endemic genus described by Greene (1887) for the Cape Region at Baja California Sur, México. The plant is a perennial herb with a subterranean bulb that persist throughout the dry season. After the first rains, the individuals complete their vital cycle forming the leaves, flowers, hit and seeds. In spite of their relative small range of distnbution (Fig. l), populations of B. tenuifíora inhabit a wide variety of habitats ranging from sarcocaulescent desert to oakpine forest. Each population is isolated, and the individuals of each population shows very different phenologies due to the different environmental conditions of the habitats. To what extent has the geographic isolation among the populations promoted plant specialization? Has subspeciation taken place or, are the differences among populations due to plastic responses by individuals? From measurements of 14 morphometnc characteristics of individuals from three populations, we would like to answer these questions. There has been no previous analysis of the differences among B. tenuifeora individuals growing under different environmental conditions. In fact, since the original description (Greene, 1887) there has been no specific study of this endemic genus /95/ $12.00/0 O 1995 Academic Press Limited

2 78 H. ROMERO-SCHMIDT ET AL. Material and methods During February and March of 1989 we collected at least 30 complete individuals of the plant from three populations growing under very different environmental conditions. The populations are called La Laguna, Matancitas and Pichilingue, according to the local names of the places where they were found (Fig. 1). Matancitas and Pichilingue are, respectively, from arid sarcocaulescent shrub and desert, while La Laguna is from a conifer forest. Because of the abundant summer rains in 1988, 1989 was a special year, B. tenuzj?ora individuals of Matancitas and Pichilingue were able to complete their vital cycle during At La Laguna B. tenuzjlora complete their cycles every year. However, at the two arid 1 Oak-Pine forest 1 o O cl 3 Scale 2 u cl O km Figure 1. Location and vegetation of study site and sampled populations.

VARIATION IN BEHRlA TENUIFLORA 79 locations it could be up to 3 years without any aerial plant parts being produced, even though bulbs are present.

3 VARIATION IN BEHRlA TENUIFLORA 79 locations it could be up to 3 years without any aerial plant parts being produced, even though bulbs are present. From each collected individual we recorded the following characteristics: and width of the bulb; scape ; of leaves and ; of flowers and pedicle ; of the perianth, stamen and pistil; capsule ;, and weight of the seeds. In order to test for statistically significant differences among the characteristics of the three populations, we applied the one way Analysis of Variance Test (ANOVA) (Campbell, 1989) followed by the Tukey-Kramer procedure (Sokal & Rohlf, 1969). The main features of the three localities were established: analysing edaphic conditions, using standard soil analysis tests (Aguilera & Martinez, 1980); elevation with an altimeter; predominant vegetation from vegetation maps (León de La Luz et al., 1988) and climate utilizing the 12-year data from nearby meteorological stations, according to the climatic system proposed by Koeppen and modified by García (1981). Results Table 1 shows the main features of the studied localities. As we can observe, the climate differs according to the elevation, and this determines the soil type and Table 1. Main features of the studied localities (see textjór the climate codes explanatwn) Locality Characteristics La Laguna Matancitas Pichilingue Location Elevation Climate Average annual temperature Average annual precipitation Soil type Vegetation B W(H) w (x') (e) 22.56'C (18.69 to 27.6) Humic Cambisol Oak-Pine Forest Eutric Regosol Sarcocaulescent scrub Eutric Regosol Sarcocaulescent desert dominant vegetation. Thus, La Laguna populations inhabit a oak-pine forest with a subhumid temperate climate [C(w)b(e)]; Matancitas populations occur in arid vegetation with a warm desert climate [BW(h')w(xl)(e)] and Pichilingue populations inhabit also in arid vegetation, but with a slightly less warm desert climate [B W(h')hw(e)]. Table 2 shows the average values for the 14 plant characteristics from the three populations. Most of the morphometric characteristics are statistically significantly different (p < 0.05) for the three populations. Except for the pedicle of the inflorescence and the pistil in the flower, al1 the other morphometric characteristics of the Sierra de La Laguna population differ from those of the other two populations.

4 80 H. ROMERO-SCHMIDT ET AL. Table 2. Average values of 14 plant characteristics of three populanh 's individuals of Behria tenuiflora. Between parenthesis is shm the standard akvialions. Populanh 1, 2, 3 are respectively La Laguna, Matancitas and Rchilingue. Zn every case the ofplant individuals measured is 30; ANOVA test degrees offieedom are 2,87 and the diferentes between populalions are shown with a p < 0.05 Variables Bulb wide Bulb Scape Laves Laves Flower Pedicle Perianth Stamens Pistil Capsule weight Localities Differences among populations The Matancitas and Pichilingue populations also diverge morphometrically for al1 the characteristics except pedicle and pistil plus scape. Table 2 shows that plant from the Sierra de La Laguna population had smaller bulbs, fewer and shorter leaves, fewer flowers, shorter stamens, shorter capsules, a larger of seeds, also longer and heavier seeds than those of the Pichilingue population. This means that the Pichilingue capsules, larger and with fewer small seeds have more air-space. The Matancitas plants were intermediate in most of their characters compared with the Sierra de La Laguna and Pichilingue individuals; they also differed statistically with them. Conclusions Plant subspeciation is a well documented process (McGrath & Quiros, 1991; Stalker

VARIATION M BEHRU TENUIFLORA 8 1 et al., 1991; Wolf et al., 1991). However, this is not the case for the study of subspeciation process in plants of arid zones.

5 VARIATION M BEHRU TENUIFLORA 8 1 et al., 1991; Wolf et al., 1991). However, this is not the case for the study of subspeciation process in plants of arid zones. Plant morphological characteristics have proved to be of use in the search of a differentiation process (Im, 1990, 1991); it has also been investigated in other taxa where geographic isolation has been the cause of subspeciation (Austin, 1992). From our results we can identify at least three ecotypes of B. tenu@ora in the Cape Region. The ecotypes of B. tenuzjlora inhabiting the oak-pine forest have smaller bulbs, shorter scapes and leaves, fewer leaves and flowers but with a greater and heavier seeds, than the Matancitas and Pichilingue arid zones populations. The individuals of the last two populations also diverge among themselves. It is now necessary to follow up with additional research, such as karyotypic, histological and molecular studies on the three populations, and also to transplant, experimentally, plants from one locality to another. However, our results do suggest the possibility that geographic isolation of the populations of B. tenuiflora in the Cape Region has promoted important morphometric differences within the species. If we also take into consideration their very different phenologies: B. tenuiflora at La Laguna appears every year, while B. tenuiflora individuals from the arid zones appear once every 3 years on average, we can conclude that we are describing a subspeciation process leading, at least, to three ecotypes in the Cape Region. This work was supported by the Centro de Investigaciones del Noroeste, the Secretaria de Programación y Presupuesto and the Consejo Nacional de Ciencia y Tecnología of México. We would like to thank Dr G. E. Wickens and Dr M. A. Khan for their very constructive and helpful suggestions to an early version of the manuscnpt. Thanks also to J. L. León de la Luz for their constructive ideas in an early phase of this work. Thanks also to D. Vázquez and to V. Hirales who typed the manuscnpt. References Aguilera C. & Martínez, M. E. (1980). Relaciones Agua, Suelo, Planta, Atmosfera, (2nd Edn.) Departamento de Enseñanza Investigación y servicio en irrigación. Chapingo, México: Universidad Autónoma Chapingo. 320 pp. Austin, G. T. (1992). Cyclonis pegala (Fabncius) (Nymphalidae: Satyrinae) in the Great Basin: new subspecies and biogeography. Bulletin of the Allyn Museum, 135: Campbell, R. C. (1989). Statistics for Biologists. Cambridge: Cambridge University Press. 445 PP. García, E. (1 98 1). Modzjicaciones al Sistema de Clasijicacwn Climática de Koeppen (para adaptarlo a las condiciones de la República Mexicana), (2nd Edn). México: Instituto de Geografía. 254 PP. Greene, E. L. (1887). Genera confused under Broidaea. Bulletin of the Califomia Academy of Science, 2: Im, H. T. (1990). An instance of quantum speciation seen in Saussurea nipponica (Compositae). Korean Joumal of Plant Taxonomy, 20: Im, H. T. (1991). Electrophoretic study of taxonomic relationships in the Saussurea nipponica complex (Compositae). Plant Species Biology, 6: León de la Luz, J. L., Domínguez, R. & Coria, R. (1988). Aspectos florísticos. In: Arriaga, L. & Ortega, A. (Eds), La Sierra de La Laguna de Baja Califomia Sur. Publication No. 1. México: Centro de Investigaciones Biológicas de BCS. 237 pp. McGrath, J. M. & Quiros, C. F. (1991). Inheritance of isozyme and RFLP markers in Brassica campestris and companson with B. oleraacea. Theoretical and Applied Genetics, 82: Sokal, R. R. & Rohlf, F. J. (1969). Biomety. New York: Freeman and Company. 859 pp. Stalker, H. T., Dhesi, J. S., Parry, D. C. & Hahn, J. H. (1991). Cytological and infertility relationships of Arachis section Arachis. American Joumal of Botany, 78: Wolf, P. G., Soltis, P. S. & Soltis, D. E. (1991). Genetic relationships and pattems of allozymic divergence in the Ipornopsis aggregata complex and related species (Polemoniaceae). American Joumal of Botany, 78:

Observations on distribution and habitat characteristics of the endangered Mexican endemic cacti Stenocereus emca

Journal of Arid Environments (1995) 29: 55-62 Observations on distribution and habitat characteristics of the endangered Mexican endemic cacti Stenocereus emca Jorge Cancino, Heidi Romero-Schmidt, Alfredo