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Reproductive ecology and conservation of the rare Dictamnus
V Congreso de Biologia de la Conservacion de Plantas 28 sept. – 1 oct. 2011 - Es Mercadal (Menorca)
Alessandro Fisogni, Martina Rossi, Giovanni Cristofolini & Marta Galloni
Department of Experimental Evolutionary Biology, University of Bologna - Italy
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
Rare and threatened both in Europe and Asia
Italy: distribution limit
Locally protected (I; EU)
Study site
Land-use change
Suitable habitats fragmented and
surrounded by agricultural landscapes; canopy closure
SCI-SPA IT4050001 Natura 2000 Network
Phenology
Phase ♂: 3.20 ± 0.20 gg Phase ♀: 2.70 ± 0.75 gg
3 steps
1 step
- Dichogamy ?Peroxidase test
In vivo pollen tubes germination
- Peroxidase activity only on upward bending stigmas
- Lack of germinated pollen grains on downward bending stigmas
Heterodichogamy
Yes: protandry
- Herchogamy
Phenology
Asynchronous maturation of flowers on the raceme - from bottom to top
In vivo germination
All pollen tubes were longer than ¾ of - or as much as - the style
0
25
50
75
100
self control
% g
erm
inat
ion
treatment
n=15 n=13
Physiologicalself-incompatibility?
No
Open pollinated controls (C)
Breeding system
Agamospermy Stigma excision
Autogamy Spontaneous (SS)
Hand-pollinated (HS)
Reproductive success
Significant diff.: SS - HS (p=0.02); SS - C (p
♂♀
Nectar analysis
: open racemes: bagged racemes
- Nectar analysis along the raceme
- Comparison between bagged and unbagged racemes
- Higher uptake in older phases
- GBNP (♀ phase)
Fisogni et al. 2011
Visitors vs.
pollinators
- Floral reward
- Flowers visited per plant
- Contact with receptive stigma
: pollinators: visitors: no obs.
Fisogni et al. 2011
Insect nRelative
abundancePollen 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
Pollinator importance
PI = relative abundance x fidelity
Direct correlation between PI Max and fruit production
Fisogni et al. 2011Galloni et al. 2008
Pollinator directionality
1
3
5
2
4b ≥1 upward
b ≈ 0 random
b < 0 downward
DirectionLine slope
Flowers in different sexual phases at the same time on the raceme
Hp: Possible geitonogamy (b ≤ 0)
Insect n b Modified Student's t
p-value
Apis mellifera 36 1.41 ± 0.35
1.64 0.05
Bombus spp. 10 1.87 ± 0.53
2.35 0.02
Megachile sp. 19 0.24 ± 0.48
- 2.22 0.02
Pollinator directionality
Modified Student’s t = (b - 1) / SEb
- Bombus and Apis: upward visits
- Megachile: random visits
b = 1: threshold beyond which geitonogamy has minor effect
No geitonogamy
Geitonogamy (weak effect)Fisogni et al. 2011
Pollinator limitation
Hand pollen supplementation
: C
: S
2007 (t-test) - Fr:fl: t = 2.15, p = 0.04 S:O: t = 2.35, p = 0.032008 (t-test) - n.s. diff.
0,2
0,4
0,6
0,8
1,0
2007 2008
Fr:fl
Year
0,100
0,325
0,550
0,775
1,000
2007 2008
S:O
Year
* *
43129 60127
In 2008 more flowering plants
Demographic study
Permanent quadrats (3x3 m) – years: 2008-2010
2 ecological situations
Wood edge
Mature wood
Class ages
Seedlings (P)
Juveniles (P2)
Young – 3 leaflets (GT)
Adults – non flowered (A)
Adults – fruited (F)
Demographic study
0
12,5
25,0
37,5
50,0
P P2 GT A F
Margine 2008
Abb
onda
nza
rela
tiva
Classi di età
0,4
15,3
30,2
45,1
60,0
P P2 GT A F
Margine 2009
Abb
onda
nza
rela
tiva
Classi di età
Wood edge2008
2009
0
15
30
45
60
P P2 GT A F
Margine 2010
Abb
onda
nza
rela
tiva
Classi di età
2010
0
15
30
45
60
P P2 GT A F
Bosco maturo 2008
Abb
onda
nza
rela
tiva
Classi di età
0
12,5
25,0
37,5
50,0
P P2 GT A F
Bosco maturo 2009
Abb
onda
nza
rela
tiva
Classi di età
0
12,5
25,0
37,5
50,0
P P2 GT A F
Bosco maturo 2010
Abb
onda
nza
rela
tiva
Classi di età
2008
2009
2010
Mature wood
n=27
n=25
n=25
n=215
n=208
n=239
rela
tive
abun
danc
ere
lativ
e ab
unda
nce
rela
tive
abun
danc
e
class ages class ages