Reproductive ecology and conservation of the rare Dictamnus

Transcription

1 Reproductive ecology and conservation of the rare Dictamnus Alessandro Fisogni, Martina Rossi, Giovanni Cristofolini & Marta Galloni Department of Experimental Evolutionary Biology, University of Bologna - Italy V Congreso de Biologia de la Conservacion de Plantas 28 sept. 1 oct Es Mercadal (Menorca)

2 Dictamnus albus L. - Long-lived perennial herb (up to 30 years) - Flowering: April-May - Fruits: star-shaped capsules - Dissemination: autochory - Habitat: edges and clearings of warm mediterranean Oak woods ( m a.s.l.) - Chorotype: eurasiatic

3 Study site SCI-SPA IT Natura 2000 Network Rare and threatened both in Europe and Asia Land-use change Suitable habitats fragmented and surrounded by agricultural landscapes; canopy closure Italy: distribution limit Locally protected (I; EU)

4 Phenology Phase : 3.20 ± 0.20 gg Phase : 2.70 ± 0.75 gg 3 steps 1 step

5 Phenology - Herchogamy - Dichogamy? Yes: protandry Peroxidase test In vivo pollen tubes germination - Peroxidase activity only on upward bending stigmas - Lack of germinated pollen grains on downward bending stigmas Heterodichogamy Asynchronous maturation of flowers on the raceme - from bottom to top

6 In vivo germination Physiological self-incompatibility? No 100 n=15 n=13 75 % germination All pollen tubes were longer than ¾ of - or as much as - the style 0 self treatment control

7 Breeding system Open pollinated controls (C) Agamospermy Stigma excision Autogamy Spontaneous (SS) Hand-pollinated (HS)

8 Reproductive success Fruit and seed set 0,600 0,463 0,325 0,188 - No agamospermy : Fr:fl : S:O SS: spontaneous selfing HS: hand-selfing C: controls Fr:fl S:O 0,050 SS HS C Treatments Significant diff.: SS - HS (p=0.02); SS - C (p<0.002) Significant diff.: SS - C (p<0.002); HS - C (p<0.001) Fisogni et al. 2011

9 Nectar analysis - Nectar analysis along the raceme - Comparison between bagged and unbagged racemes - GBNP ( phase) - Higher uptake in older phases : open racemes : bagged racemes Fisogni et al. 2011

10 : pollinators : visitors : no obs. Visitors vs. pollinators - Floral reward - Flowers visited per plant - Contact with receptive stigma Fisogni et al. 2011

11 Pollinator importance PI = relative abundance x fidelity Insect n Relative abundance Pollen fidelity PI Apis mellifera Bombus spp Megachile sp Direct correlation between PI Max and fruit production Galloni et al Fisogni et al. 2011

12 Pollinator directionality Line slope Direction b 1 upward 1 2 b 0 random b < 0 downward Flowers in different sexual phases at the same time on the raceme Hp: Possible geitonogamy (b 0)

13 Pollinator directionality Insect n b Modified Student's t p-value b = 1: threshold beyond which geitonogamy has minor effect Apis mellifera 36 Bombus spp ± ± Megachile sp ± Modified Student s t = (b - 1) / SE b - Bombus and Apis: upward visits - Megachile: random visits No geitonogamy Geitonogamy (weak effect) Fisogni et al. 2011

14 Pollinator limitation Hand pollen supplementation : C : S 1,0 0,8 * * 1,000 0,775 Fr:fl 0,6 S:O 0,550 0, ,325 0, Year 0, Year 2007 (t-test) - Fr:fl: t = 2.15, p = 0.04 S:O: t = 2.35, p = (t-test) - n.s. diff. In 2008 more flowering plants

15 Demographic study 2 ecological situations Wood edge Mature wood Permanent quadrats (3x3 m) years: Seedlings (P) Juveniles (P2) Class ages Young 3 leaflets (GT) Adults non flowered (A) Adults fruited (F)

16 Demographic study Bosco maturo 2008 Abbondanza relativa Abbondanza relativa Abbondanza relativa 50,0 37,5 relative abundance relative abundance relative abundance 25,0 12,5 0 60,0 45,1 30,2 15, ,4 0 Margine 2008 Wood edge 2008 n=215 P P2 GT A F Classi di età Margine n=208 P P2 GT A F Classi di età Margine 2010 P P2 GT A F Classi di età 2010 n=239 Abbondanza relativa Abbondanza relativa Abbondanza relativa ,0 37,5 25,0 12,5 0 50,0 37,5 25,0 12,5 0 Mature wood 2008 n=27 P P2 GT A F Classi di età Bosco maturo n=25 P P2 GT A F Classi di età Bosco maturo n=25 P P2 GT A F Classi di età class ages class ages