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Dispersal mechanisms of the narrow endemic Polygala vayredae: dispersal syndromes and spatio-temporal variations in ant dispersal assemblages
S. Castro, V. Ferrero, J. Loureiro, X. Espadaler, P. Silveira, L. Navarro
Plant Ecololy, DOI 10.1007/s11258-009-9679-z

Figure. Dispersal of Polygala vayredae seeds by Formica gagates; a mature capsule with exposed seeds; b ant exploration; c seed detection; d seed removal; e seed transportation; f empty capsule fixed to the mother plant

Abstract. The present study assesses the dispersal mechanisms of the narrow endemic Polygala vayredae, analysing the functioning of its dispersal syndromes (anemochory and myrmecochory), the spatio-temporal variability of the disperser assemblage, foraging behaviour and dispersal ability, and the role of the elaiosome in ant attraction and seed germination. The dispersion of diaspores begins when either (1) capsules or seeds fall beneath the mother plant (barochory) or (2) the seeds are directly collected in the suspended capsules by ants (myrmecochory). As capsules frequently open and expose/disseminate seeds before leaving the mother plant, the adaptation for anemochory appears to be reduced and rarely functional, possibly with only occasional events of long-distance dispersal (e.g., under extreme weather conditions). P. vayredae is essentially myrmecochorous and a diverse array of ant species are involved in seed manipulation, with the elaiosome playing a major role in ant attraction. From the plant’s perspective for dispersal, the majority of ant species had a positive interaction with the seeds, but negative and potential neutral interactions were also observed. Overall, dispersal distances were limited and were mainly determined by ant body size. The frequency of interactions and the ant assemblage varied significantly both spatially and temporally, and these factors may have an effect on directing or disrupting the selection of plant traits. Low seed predation and similar germination rates of intact seeds compared with seeds without elaiosome indicate that seed predator avoidance and seed germination improvement after ant manipulation are not among the selective advantages of myrmecochory operating at present. Dispersal mechanisms that enhance seed dispersal within the population and only occasionally lead to long-distance dispersal events, along with the rarity and patchiness of suitable habitats, may be the main factors explaining the actual density and narrow distribution of this species.

Pollination Biology Course

Where: Faculty of Science, Charles University in Prague, CZ
When: 25-27 January 2010

Organisers: Jana Jersáková (1) and Sílvia Castro (2)
(1) Faculty of Science, Univ. of South Bohemia, České Budějovice; Institute of System Biology and Ecology ASCR, České Budějovice, Czech Republic
(2) Centre for Functional Ecology, Department of Life Sciences, Faculty of Science and Technology, University of Coimbra, Coimbra, Portugal

In the first two days the course will cover topics related to main concepts in plant pollination biology such as pollination syndromes, mating strategies and sexual systems, pollinator effectiveness, visual, olfactory and tactile cues used in pollinator attraction. On the third day we will present two more specialized topics based specific examples of studies dealing with Deception and floral mimicry in plants and sexual polymorphisms. The course will be accompanied by discussions of review papers, student’s presentations of case studies and practical sessions showing some techniques widely used in pollination studies.

2nd Workshop on Invasive Alien Plants in Mediterranean Type Regions of the World

02-06 August 2010, Samsun, Turkey

The first announcement is now available on the EPPO website at: http://archives.eppo.org/MEETINGS/2010_conferences/mediterranean_ias.htm

The Workshop has several objectives: to be a global platform for networking, an opportunity for discussing specific plant invasions issues, a place to learn about varied topics within biological invasions and a chance for raising awareness on this issue in the Mediterranean Type regions of the World.

Organization: This workshop will be co-organized by the Turkish Plant Protection Organization, the Council of Europe and EPPO. The workshop will consist of 2 days of presentations and discussions, and will be followed by 2 days of field work to create inventories of the exotic flora of the Samsun area to contribute to the knowledge on invasive alien plants.

Evolutionary ecology of polyploids: understanding species coexistence at the contact zones

The polyploid Aster amellus

Polyploidy has long been recognized as a major mechanism in plant speciation and evolution, occurring in up to 70% of the flowering plants and being distributed in numerous plant lineages. As new evolutionary entities can arise in a single genetic event, polyploidy has been proposed as an important mechanism of sympatric speciation. Facing the potential of polyploidy for sympatric speciation, several studies have addressed the ecological and genetic conditions governing the interactions between diploid and polyploids in mixed populations. The theories preview that under random mating, the establishment of a new cytotype will be subjected to strong frequency-dependent selection (minority cytotype exclusion) and new cytotype establishment and maintenance in mixed populations will occur only if a set of breeding barriers and/or ecological features promote assortative mating.

Figure 1. A. Flower of Aster amellus being visited by a Diptera. B. Experimental crosses between cytotypes being performed under controlled conditions at the experimental garden.

In this frame work, we are studying the breeding barriers involve in the maintenance of a diploid-hexaploid contact zone of the polyploidy Aster amellus (Figure 1A). Data on cytotype distribution, habitat and temporal segregation, pollinator behaviour and preferences, ability to cross (Figure 1B) and viability of the offspring is being investigated. This project is being developed by Sílvia Castro and Zuzana Münzbergová at the Department of Botany of the Charles University in Prague (Czech Republic).

6th European Conference on Biological Invasions NEOBIOTA 2010

Organised by Johannes Kollmann, Hans Peter Ravn and Lotte Endsleff (University of Copenhagen)

Biological Invasions in a Changing World - from Science to Management

NEOBIOTA 2010 focuses on biological invasions in a changing environment, including contributions from science and management across all species groups, habitats or regions. The conference will take place on 14-17 September 2010 in Copenhagen, Denmark, starting with an invited evening keynote lecture presented by Richard J. Hobbs from the Murdoch University in Western Australia.

Registration deadline: 15 March 2010
For further information on program, organizers and scientific committee, conference venue, oral and poster contributions, registration and other details, visit the conference website at http://cis.danbif.dk/neobiota2010.