Abstract
We studied an insect-plant pollination system in adjacent steep-sided wadis and a connecting plain in the mountains of southern Sinai (Egypt): this environment creates a strongly divided habitat, which may promote the local differentiation of sub-populations. We tested for spatial differences in phenotypic reproductive characters of the only plant flowering abundantly in early spring, Alkanna orientalis (Boraginaceae), and its major pollinator at that time of year, Anthophora pauperata (Apoidea, Anthophoridae). There were significant morphological differences between sub-populations of Alkanna, mainly between plants from the narrower wadis and those on the interconnecting plain. Flowers on the plain were larger, with wider corollas and more nectar standing crop; these plants retained more flowers on the inflorescence, but received many fewer visits to flowers. There was a significant selection gradient between flower size and maternal fitness (seed set) in the plain, but not elsewhere. Natural selection may have increased resources devoted to attracting insect visitors in response to fewer pollinating visits in the plain. Consistent with this explanation, by experimentally manipulating flower number per plant, we showed that within a wadi having more flowers on a plant secured more visits.
Similar content being viewed by others
References
Andersson S (1988) Size-dependent pollination efficiency in Anchusa officinalis (Boraginaceae): causes and consequences. Oecologia 76:125–130
Armbruster WS (1985) Patterns of character divergence and the evolution of reproductive ecotypes of Dalechampia scandens (Euphorbiaceae). Evolution 39:733–752
Armbruster WS (1990) Estimating and testing the shapes of adaptive surfaces: the morphology and pollination of Dalechampia blossoms. Am Nat 135:14–31
Barnard CJ, Gilbert FS, McGregor PK (1993) Asking questions in biology. Longman, London
Bell G (1985) On the function of flowers. Proc R Soc Lond B 224:223–265
Bierzychudek P (1981) Pollinator limitation of plant reproductive effort. Am Nat 117:838–840
Crawley M (1993) GLIM for ecologists. Blackwell, Oxford
Davis PH (ed) (1978) Flora of Turkey, vol. 6. Edinburgh University Press, Edinburgh
Dewedar A (1991) The Sinai desert training centre (reports 1-4). Foreign Relations Coordination Unit (Grant 90031), Supreme Council of Universities, Egypt
Eckhart VM (1991) The effects of floral display on pollinator visitation vary among populations of Phacelia linearis (Hydrophyllaceae). Evol Ecol 5:370–384
Geber MA (1985) The relationship between plant size to self-pollination in Mertensia ciliata. Ecol 66:762–772
Herrera CM (1990a) The adaptedness of the floral phenotype in a relict endemic, hawkmoth-pollinated violet. 1. Reproductive correlates of floral variation. Biol J Linn Soc 40:263–274
Herrera CM (1990b) The adaptedness of the floral phenotype in a relict endemic, hawkmoth-pollinated violet. 2. Patterns of variation among disjunct populations. Biol J Linn Soc 40:275–291
Herrera CM (1991) Dissecting factors responsible for individual variation in plant fecundity. Ecology 72:1436–1448
Herrera CM (1993) Selection on floral morphology and environmental determinants of fecundity in a hawkmoth-pollinated violet. Ecol Mongr 63:251–275
Johnston MO (1991) Natural selection on floral traits in two species of Lobelia with different pollinators. Evolution 45:1468–1479
Klinkhamer PGL, Jong TJ de (1990) Effects of plant size, plant density and sex differential nectar reward on pollinator visitation in the protandrous Echium vulgare (Boraginaceae). Oikos 57:399–405
Klinkhamer PGL, Jong TJ de, Bruyn G-J de (1989) Plant size and pollinator visitation in Cynoglossum officinale. Oikos 54:201–204
Lande R, Arnold SJ (1983) The measurement of selection on correlated character. Evolution 37:1210–1226
Mansour RMA, Saleh NAM (1986) The flavonids of Alkanna orientalis. J Nat Prod (Lloydia) 49:356
Meddis R (1984) Statistics using ranks. Blackwell, Oxford
Murcia C (1990) Effect of floral morphology and temperature on pollen receipt and removal in Ipomoea trichocarpa. Ecology 71:1098–1109
Polunin O, Huxley A (1972) Flowers of the Mediterranean. Chatto and Windus, London
Primack RB, Kang H (1989) Measuring fitness and natural selection in wild plant populations. Annu Rev Ecol Syst 20:367–396
Rasmussen IR, Brodsgaard B (1992) Gene flow inferred from seed dispersal and pollinator behaviour compared to DNA analysis of restriction site variation in a patchy population of Lotus corniculatus L. Oecologia 89:277–283
Rechinger KH (1965) Towards knowledge of the European species of the genus Alkanna (in German). Ann Naturhist Mus Wien 68:191–220
Redmond AM, Robbins LE, Travis J (1989) The effects of pollination distance on seed production in three populations of Amianthium muscaetoxicum (Liliaceae). Oecologia 79:260–264
Schemske DW, Horvitz CC (1984) Variation among floral visitors in pollination ability: a precondition for mutualism specialization. Science 225:519–521
Schemske DW, Horvitz CC (1989) Temporal variation in selection on a floral character. Evolution 43:461–465
Schmid-Hempel P, Speiser B (1988) Effects of inflorescence size on pollination in Epilobium angustifolium. Oikos 53:98–104
Schmitt JA, Gamble SE (1990) The effect of distance from the parental site on offspring performance and inbreeding depression in Impatiens capensis: a test of the local adaptation hypothesis. Evolution 44:2022–2030
Semida FM (1994) Insect-plant coevolution in the Sinai desert ecosystem. PhD Thesis, Suez Canal University, Ismailia, Egypt
Sih A, Baltus M-S (1987) Patch size, pollinator behaviour, and pollinator limitation in catnip. Ecology 68:1679–1690
Sowig P (1989) Effects of flowering plant's patch size on species composition of pollinator communities, foraging strategies, and resource partitioning in bumblebees (Hymenoptera, Apidae). Oecologia 78:550–558
Stanton ML, Young HJ, Ellstrand NC, Clegg JM (1991) Consequences of floral variation for male and female reproduction in experimental populations of wild radish, Raphanus sativus L. Evolution 45:268–280
Stewart SC, Schoen DJ (1987) Pattern of phenotypic variability and fecundity selection in a natural population of Impatiens pallida. Evolution 41:1290–1301
Täckholm V (1974) Students' Flora of Egypt, 2nd edn. Cairo University, Beirut
Tutin TG, Heywood VH, Burges NA, Moore DM, Valentine DH, Walters SM, Webb DA (1972) Alkanna. Flora Europaea 3:95–97
Waser NM, Price MV (1991) Outcrossing distance effects in Delphinium nelsonii: pollen loads, pollen tubes and seed set. Ecology 72: 171–179
Weast RC (ed) (1985) CRC Handbook of Chemistry and Physics. CRC, Boca Raton
Widen B, Widen M (1990) Pollen limitation and distance-dependent fecundity in females of the clonal dioecious herb Glechoma hederacea (Lamiaceae). Oecologia 83:191–196
Willmer PG, Gilbert FS, Ghazoul J, Semida F, Zalat SM (1994) A novel form of territoriality: daily paternal investment in an anthophorid bee. Anim Behav 46:535–549
Wilson P, Thomson JD (1991) Heterogeneity among floral visitors leads to discordance between removal and deposition of pollen. Ecology 72:1503–1507
Young HJ, Stanton ML (1990) Influences of floral variation on pollen removal and seed production in wild radish. Ecology 71:536–547
Zimmerman M, Pyke GH (1988) Reproduction in Polemonium: assessing the factors limiting seed set. Am Nat 131:723–738
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Gilbert, F., Willmer, P., Semida, F. et al. Spatial variation in selection in a plant-pollinator system in the wadis of Sinai, Egypt. Oecologia 108, 479–487 (1996). https://doi.org/10.1007/BF00333724
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00333724