disa uniflora

African terrestrial orchids
Benny Bytebier
Bews Herbarium, School of Biological and Conservation Sciences
University of KwaZulu-Natal, Pietermaritzburg, South Africa
Outline
Part 1
Diversity, classification and
D. atricapilla
biogeography of Disa
Part 2
Conservation of Disa barbata
D. barbata
1300
259
1621
557
8650
11669
2749
1271
5
19(12)
111(14)
432(57)
240(40)
970(75)
808(74)
755(66)
560(53)
1214(70)
Southern Africa 466 species, 53 genera
302 species and 8 genera endemic
CFR 227 species; 138 species and 5 genera endemic
Disa uniflora
SA: 146/466 sp. (31%) belong
to Disa
CFR: 100/227 sp (44%)
belong to Disa
14th biggest genus in the CFR
Disa
• 180 species; terrestrial
• widespread in Africa, into
Madagascar, Réunion, Arabia
• many species in the CFR
(100/180 species)
•most species in fynbos or
Afromontane grassland
• diversity decreases northwards
and westwards
from Linder, 1983
• share pattern with many others
e.g. Restionaceae, Moraea,
Pentaschistis, Stoebe, Lobelia,
Cyphia, Protea, Erica, etc
Disa uniflora
Disa maculata
Herschelia spathulata
Schizodium flexuousum
Monadenia brevicornis
Disa telipogonis
Penthea filicornis
Questions
1.
What are the relationships amongst the different
species of Disa? One genus; or more than one?
2.
Where did the genus Disa originate and how did it
spread through Africa?
Approach
• Collect samples of as many species as possible
• Isolate DNA
• Photocopy (PCR) some parts of the DNA and sequence
• Compare the sequences and build a tree of relationships
• Propose a new classification (taking all evidence in account)
Challenges
• Many Disa species are rare!
Type only
12
7%
Less than 3 specimens
6
3.5%
Rare or Very Rare
40
23 %
• Many Disa species prefer to grow on tops of
mountains
• Many Disa species flower ONLY the first year after
fire
D. linderiana
Cedarberg
Cedarberg
?
e Peninsula
D. densiflora
D. obtusa ssp obtusa
Romansrivier
D. longipetala
126 out of 180 (70 %) species were sampled
3 genes sequenced, matrix with 4094 characters
Good amount
of congruence
with the
current
sectional
classification
1 genus - 18 sections
• morphologically
distiguishable
• maximum overlap with
previous classification
A - § Vaginaria - D. fasciata
B - § Disella - D. obtusa
C - § Phlebidia - D. longicornu
D - § Coryphaea - D. triloba
E - § Disa - D. uniflora
F - § Schizodium - D. flexuosa
G - § Spirales - D. tenella
H - § Ovalifoliae - D. ovalifolia
I - § Atromaculiferae - D. glandulosa
J - § Pardoglossa - D. rosea
K - § Monadenia – D. brevicornis
L - § Repandra – D. cornuta
M - § Emarginatae – D. stachyoides
N - § Reticulibractea – D. draconis
O - § Trichochila – D. barbata
P - § Stenocarpa – D. gladioliflora
Q - § Aconitoideae – D. aconitoides
R - § Micranthae – D. chrysostachya
• Apart from a new classification, what can we learn
from a phylogenetic tree?
• Example: phytogeography
• Where did the genus Disa originate and how did it
spread through Africa?
•3 theories
•Vicariance (Adamson, 1958)
•North to South (Levyns, 1964)
•South to North (Linder, 1994)
•How can we decide?
Origin = Cape
C
5
4
3
2
1
Cape
Cape
Cape
Cape
Cape
C
5
4
3
2
1
Cape
Cape
Cape
Cape
Drakensberg
C
C
C
C
C
C
species 1 dispersed from Cape to Drakensberg
Areas
(Linder, 1983)
Eastern
Africa (EA)
Western Africa
(WA)
South-Central
Africa (SCA)
Zimbabwe Overlap
Region (Z)
Madagascar
(MAD)
• Réunion
(REU)
Greater Cape
Floristic Region
(GCFR)
Drakensberg
(DRAK)
WA
EA
2 (3?)
1
3 (4?)
?
SCA
(4?)
5 (6?)
3 (7?)
MAD
2 (5?)
Z
• REU
1 (2?)
DRAK
Origin of Disa = Cape
6 (10?)
GCFR
1
Conclusions
• Disa originated in the Greater Cape Floristic Region
• From the GCFR there was directional migration east
to the Drakensberg and then northwards into Africa
• Our data refute the southward migration of Disa
from tropical Africa into the GCFR
Part 2
Conservation of Disa barbata
• Historical records indicate : on flats around Cape Town
• Last collection: 1950
• 1 remaining population known, 50 km North of Cape Town
• When visited in 2001 – only 8 plants seen
• Near extinction???
1 November
15 August
Since 2002, on yearly basis, we
• Walk transects
• GPS/mark all plants individually
• Count flowers
6 weeks later
• Trace
the markers by GPS
• Count seed pods
• Pollinator observations
• Hand pollination
• Seed collection
• In vitro seed germination
Some results
• end 2006 > 200 plants documented, including new site
outside reserve
• plants do not flower every year but leaves come up yearly
• pollinator = Xylocopa rufitarsis (carpenter bee)
• within reserve
•steady decline of plants in flower (as the surrounding
vegetation gets higher)
•decline in pollination success (15% to 0%)
• in vitro germination methods developed; in vitro plants were
raised, weaned and first batch of plants re-introduced in a
historical site i.e. Kenilworth Race Course (Cape Town)
FIRE !!
• Summer (Feb/Mar) 2006 a fire went through the site
outside the reserve
• November 2006, not a single plant seen!
• November 2007 >400 plants counted, high pollination
success
• November 2008 similar
• Clearly plants go through a natural cycle in which fire
plays an important role
• Project still ongoing, but the results have already given
us a better insight in the natural history of D. barbata,
which will is essential for any meaningful, long-term
conservation programme
THANK YOU
Kogelberg Mts. – False Bay