Pollination biology of Silene species in Israel (Andreas Jürgens & Taina Witt)

Phytogeographically, Israel is unique, being the place where four different floras meet. The flora is very rich with ca. 2600 species of higher plants, distributed among ca. 130 families on a relatively small area.

The pollination biology of some northern European and American species has been investigated (e.g. Brantjes & Leemans 1976, Jennersten 1988, Pettersson 1991, Jürgens et al. 1996), but despite the centered distribution of Silene in the Mediterranean and the Middle East nearly nothing is known about the ecological interactions of the genus in this area.

In Israel about 39 Silene species are reported, some of them are endemic. It would be interesting to know if the interactions between flowers and their flower visitors are more specific compared to species of North West Europe that live under colder and more unpredictable weather conditions.

The study will be located at the University of Haifa in the Laboratory of Pollination Ecology with Prof. Amots Dafni.

	Green The Mediterranean woodlands and shrublands Brown Irano-Turanian steppe vegetation  Yellow Saharo Arabian, desertic vegetation  Purple Tropical Sudanian vegetation
The picture has been taken from The Department of Plant Sciences "Remarks on Flora and Vegetation in the Land of Israel" [www.tau.ac.il/lifesci/botany/flora.htm]

Goals of the project: The proposed project deals with the pollination biology of Silene species in Israel and will focus on the following goals: 

(1) Recording of flower visitor spectra in day- and night-flowering Silene species Flower visitor spectra will be recorded in selected plant populations in field. Observations on the behaviour of the flower visitors will reveal what kind of food resources are used by the insects (nectar or pollen). 

(2) Characterisation of flower features A quantitative analysis of the flower morphology (in relation to the morphology of the flower visitors) will give an insight into the function of the flower as an integrated system. Furthermore, adaptations to pollinators, such as the time of flower opening, rhythm of nectar secretion, and odour emission will be studied. 

(3) Analysis of floral odour composition and bioassays to evaluate the importance of floral scent compounds for the attraction of flower visitors To identify odour compounds that might be important for the attraction of insects odours will be sampled from flowers in field. The floral scent composition will be analysed via GC-MS/MS in cooperation with the Department of Plant Systematics at University of Bayreuth (Germany). Behavioural tests with selected pollinator species will be carried out to investigate the role of biologically active odour compounds in attracting pollinators. 

(4) Evaluation of the breeding system and pollination efficiency of flower visitors To gain a better understanding of the pollinator efficiency and the effect of different pollinator types on the evolution of pollen production in Silene pollen-ovule ratios (P/O) will be investigated. Pollen-ovule ratios reflect the pollination efficiency, i.e., the likelihood of a pollen grain reaching the stigma and there is evidence that P/Os are also affected by the sexual system, the pollen vectors, pollination mechanisms, and ecological factors (Jürgens et al. 2002a). A set of fluorescent dyes that function as traceable non-genetic markers will be used to assess differences in visitation patterns of the pollinator guilds, and to get an estimation of pollen-flow within and between populations. 

(5) Studies on interactions with Hadena moths as seed predators and pollinators In general, larvae of this genus Hadena feed on plants of the family Caryophyllaceae, especially on their seeds (Brantjes 1976, Wolfe 2002, Bopp 2003, Dötterl 2004). At least for central European species it is known that the moths are very specific in the choice of food plants (Steiner & Ebert 1998). Although we know for example that Hadena perplexa (DENIS & SCHIFFERMÜLLER) is occurring in Israel (Hacker 1996) there is no data on the interaction of this species with its potential host plant(s) in Israel.

Bopp S, Gottsberger G. 2004. Importance of Silene latifolia spp. alba and S. dioica (Caryophyllaceae) as host plants of the parasitic pollinator Hadena bicruris (Lepidoptera, Noctuidae). Oikos 105:221-228. 

Brantjes NBM, Leemans JAAM. 1976. Silene otites (Caryophyllaceae) pollinated by nocturnal Lepidoptera and mosquitoes. Acta Botanica Neerlandica 25:281-295. 

Brantjes NBM. 1976. Riddles around the pollination of Melandrium album (Mill.) Garcke (Caryophyllaceae) during the oviposition by Hadena bicruris Hufn. (Noctuidae, Lepidoptera), II. Proc. Koninkl. Ned. Akad. Wetensch., Ser. C 79:125-141.

Dötterl S. (2004). Importance of floral scent compounds for the interaction between Silene latifolia (Caryophyllaceae) and the nursery pollinator Hadena bicruris (Lepidoptera: Noctuidae). PhD thesis, University of Bayreuth (Germany).

Greuter W. 1995. Silene (Caryophyllaceae) in Greece: a subgeneric and sectional classification. Taxon 44: 543-581.

Jürgens A, Witt T, Gottsberger G. 1996. Reproduction and pollination in Central European populations of Silene and Saponaria species. Botanica Acta 109:316-324.

Jürgens A, Witt T, Gottsberger G. 2002a. Pollen grain numbers, ovule numbers and pollen-ovule ratios in Caryophylloideae: correlation with breeding system, pollination, life form, style number, and sexual system. Sexual Plant Reproduction 14:279-289. 

Jennersten O. 1988. Pollination of Viscaria vulgaris (Caryophyllaceae): the contribution of diurnal and nocturnal insects to seed set and seed predation. Oikos 52:319-327.

Pettersson MW 1991. Pollination by a guild of fluctuating moth populations: option for unspecialisation in Silene vulgaris. J Ecol 79:591-604.

Steiner A, Ebert G. 1998. Die Schmetterlinge Baden-Württembergs: Nachtfalter V. Eugen Ulmer, Stuttgart.

Wolfe LM. 2002. Why alien invaders succeed: support for the escape-from-enemy hypothesis. Am. Nat. 160, 705-711.

_{Andreas Jürgens}