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. 2011 - Es Mercadal (Menorca)
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 (100-800 m a.s.l.) - Chorotype: eurasiatic
Study site SCI-SPA IT4050001 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)
Phenology Phase : 3.20 ± 0.20 gg Phase : 2.70 ± 0.75 gg 3 steps 1 step
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
In vivo germination Physiological self-incompatibility? No 100 n=15 n=13 75 % germination 50 25 All pollen tubes were longer than ¾ of - or as much as - the style 0 self treatment control
Breeding system Open pollinated controls (C) Agamospermy Stigma excision Autogamy Spontaneous (SS) Hand-pollinated (HS)
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
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
: pollinators : visitors : no obs. Visitors vs. pollinators - Floral reward - Flowers visited per plant - Contact with receptive stigma Fisogni et al. 2011
Pollinator importance PI = relative abundance x fidelity Insect n Relative abundance Pollen fidelity PI Apis mellifera 8 0.13 0.94 0.12 Bombus spp. 11 0.19 0.68 0.13 Megachile sp. 7 0.11 0.72 0.08 Direct correlation between PI Max and fruit production Galloni et al. 2008 Fisogni et al. 2011
Pollinator directionality Line slope Direction 5 3 4 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)
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. 10 1.41 ± 0.35 1.87 ± 0.53 1.64 0.05 2.35 0.02 Megachile sp. 19 0.24 ± 0.48-2.22 0.02 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
Pollinator limitation Hand pollen supplementation : C : S 1,0 0,8 * * 1,000 0,775 Fr:fl 0,6 S:O 0,550 0,4 129 43 127 60 0,325 0,2 2007 2008 Year 0,100 2007 2008 Year 2007 (t-test) - Fr:fl: t = 2.15, p = 0.04 S:O: t = 2.35, p = 0.03 2008 (t-test) - n.s. diff. In 2008 more flowering plants
Demographic study 2 ecological situations Wood edge Mature wood Permanent quadrats (3x3 m) years: 2008-2010 Seedlings (P) Juveniles (P2) Class ages Young 3 leaflets (GT) Adults non flowered (A) Adults fruited (F)
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 15,3 60 45 30 15 0,4 0 Margine 2008 Wood edge 2008 n=215 P P2 GT A F Classi di età Margine 2009 2009 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 60 45 30 15 0 50,0 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 2009 2009 n=25 P P2 GT A F Classi di età Bosco maturo 2010 2010 n=25 P P2 GT A F Classi di età class ages class ages