Download Appendix S2 Disjunction and barrier ages

Danthonioid biogeography: ecology and history. Appendix S2. Page 1
SUPPORTING INFORMATION
What determines biogeographical ranges? Historical wanderings and ecological
constraints in the danthonioid grasses
H. Peter Linder, Alexandre Antonelli, Aelys M. Humphreys, Michael D. Pirie and
Rafael O. Wüest
Journal of Biogeography
Appendix S2 Disjunction and barrier ages (a) and areas of endemism of Danthonioideae (b).
(a) Disjunction and barrier ages
In order to test the assumption that range expansions could occur only with long-distance dispersal, we
compared the age ranges over which each disjunction was established to the age of the ‘barrier’ (Table
S2-1). The age range over which the disjunction was established is taken be between the maximum
95% highest posterior density (HPD) of the stem node and the minimum 95% HPD of the crown node,
on the dated tree.
Danthonioid biogeography: ecology and history. Appendix S2. Page 2
Table S2-1 Comparison of the age of the disjunct distribution with the time when the barrier was
established. ‘Disjunct taxon’ refers to a taxon that is spatially disjunct from its sister-taxa; ‘Age range’
refers to the maximum 95% HPD of the stem clade and the minimum 95% HPD of the crown clade. In
the case of single species, this is taken as zero. ‘Disjunction’ refers to the two areas in which the sister
clades occur, and ‘Barrier’ refers to the gap between. ‘Age’ refers to the seafloor if the barrier is
marine (dates taken from McLoughlin, 2001); if it is terrestrial, a more detailed description is
presented below (a–d).
Disjunct taxon
Chionochloa
Pentameris insularis
Rytidosperma
Pentameris andringitrensis
Danthonia alpina
Pentameris pictigluma
Tenaxia subulata
Danthonia
Tenaxia cumminsii
Schismus arabicus
Schismus barbatus
Chimaerochloa
Notochloe plastid
Rytidosperma violaceum clade
Austroderia
Cortaderia plastid
Danthonia clade
Chionochloa frigida
Notochloe–Plinthanthesis
Rytidosperma australe
Rytidosperma exiguum
Rytidosperma gracile
Rytidosperma pulchrum clade
Rytidosperma pumilum
Rytidosperma thomsonii clade
Age range (Ma)
18.66–4.35
2.42–0
10.2–3.6
14.46–0
4.52–0.48
4.7–1.03
10.86–2.82
7.73–2.86
10.86–2.82
7.96–1.44
5.42–0
7.73–0
3.09–0
5.1–1.04
9.55–0.66
16.69–3.76
16.03–7.83
1.58–0
9.55–1.93
2.53–0
3.67–0
1.58–0
5.1–1.45
1.4–0
3.33–0.68
Disjunction
Africa–New Zealand
Africa–Amsterdam Island
Africa–Australia
Africa–Madagascar
America–Europe
S–E Africa
S–E Africa
S America–N America
Africa – Himalayas
S–N Africa
S–N Africa
S America–New Guinea
Australia–S America
Australia–S America
S America–New Zealand
Africa–S America
Africa–S America
Australia–New Zealand
Australia–New Zealand
Australia–New Zealand
Australia–New Zealand
Australia–New Zealand
Australia–New Zealand
Australia–New Zealand
Australia–New Zealand
Barrier
Indian Ocean
Indian Ocean
Indian Ocean
Mozambique Strait
N Atlantic Ocean
Overland
Overland
Overland
Overland
Overland
Overland
Pacific Ocean
Pacific Ocean
Pacific Ocean
Pacific Ocean
S Atlantic Ocean
S Atlantic Ocean
Tasman Sea
Tasman Sea
Tasman Sea
Tasman Sea
Tasman Sea
Tasman Sea
Tasman Sea
Tasman Sea
Age (Ma)
105–120
105–120
105–120
130–160
52–55
a
a
b
c
d
d
30–50
30–50
30–50
95–76
105–119
105–119
95–76
95–76
95–76
95–76
95–76
95–76
95–76
95–76
Danthonioid biogeography: ecology and history. Appendix S2. Page 3
(a) South–East Africa disjunction
Currently the danthonioids are restricted to the volcanoes in East Africa, and are absent from both the
uplands flanking the rift valleys and the lowlands. The lowlands (the major valleys of the Limpopo,
Zambezi, the extensive Tanzanian and Kenyan lowlands and the Congo basin) appear to have always
been tropical, and fluctuated during the Neogene between savanna and rain forest (Wichura et al.,
2010). Uplift of the plateaux flanking the rifts was initiated in the middle Miocene (Wichura et al.,
2010), while volcano construction was during the whole of the Neogene (Grove, 1983). It is possible
that the range of the danthonioids in East Africa was considerably expanded during the Pleistocene
glacials, when lower temperatures (Hamilton, 1982; Bonnefille & Bonnefille, 1988; Bonnefille et al.,
1995) might have allowed them to occupy the extensive uplands in Malawi (Shire Highlands, Nyika),
Tanzania (Southern Highlands, Kitulo, Ufipa), Burundi, Rwanda, southern Uganda and the Kikuyu
uplands of Kenya. This would have substantially reduced the interval between the southern African
and East African populations.
(b) South America–North America disjunction
This became an overland disjunction with the closure of the Panama Isthmus, at c. 3.5 Ma. During the
6 Myr preceding the closure, occasional migration occurred, possibly facilitated by the relative
proximity (c. 200 km) of the South and North American continents since the middle Miocene (Montes
et al., 2012). Then, and also since the closure, the vegetation appears to have fluctuated between rain
forest and savanna (Woodburne, 2010; Smith et al., 2012), neither of which constitutes suitable
danthonioid habitat. This disjunction may well have stayed the same size as currently throughout the
Neogene, especially as the estimated timing of the Danthonia disjunction is largely before the Isthmus
was closed.
(c) Africa–Himalayas disjunction
The reconstructions for the South–North African disjunction also apply to the Africa–Himalayas
disjunctions, and even during the Holocene optimum at 6 ka the desert was still only a savanna (Jolly
et al., 1998).
(d) South–North Africa disjunction
This disjunction crosses the Sahara, which has had desert conditions at least since 7 Ma (Schuster et
al., 2006), with wetter periods being more savanna-like but never temperate (Jolly et al., 1998).
However, during wetter periods the Congo basin would have been more densely forested. This barrier
is thus much older than the danthonioid disjunction.
The oceanic disjunction sizes would not have changed much during the Neogene, except
possibly the distance between the Madagascan uplands and the East African uplands.
Danthonioid biogeography: ecology and history. Appendix S2. Page 4
(b) Areas of endemism
Area name
Area definition and notes
Southern Africa
South of Malawi, includes both the Cape flora and the temperate
montane grasslands of the Drakensberg.
Central–East Africa
From central Tanzania to the Yemen, and Mount Cameroon,
including the higher Rift Valley mountains. The single species of
Merxmuellera is known only from the type collection.
Mount Cameroon
With a single species, Pentameris mannii, dubiously distinct from
the East African P. pictigluma.
Madagascar
There are no species on the Mascarenes. Madagascar is very
under-represented in the phylogeny.
Amsterdam Island
Only Pentameris insularis.
Himalayas
From Pakistan to Yunnan.
Australia
Including Tasmania, but not New Guinea. There are numerous
species shared between the mountains of southern Australia and
Tasmania, while the species of New Guinea are shared with the
mountains in Southeast Asia.
New Guinea and Southeast Asia
Based on shared species.
Lord Howe Island
A single species (Chionochloa howensis), not sampled for the
phylogeny.
New Zealand
Including surrounding islands. These either have no endemic
species (Stewart Island) or are less than 1000 km from the main
islands (Auckland, Chatham, Pitt and Campbell Islands).
Easter Island
A single, endemic, species (Rytidosperma paschale). This species
is probably not distinct from R. racemosa and may be an
anthropogenic introduction.
South America
From Tierra del Fuego to Panama.
North America
North of Panama, including NE Asia (Kamchatka), which shares a
species with northern North America.
West Indies
A single species on Hispaniola (Danthonia domingensis)
Central Europe
In the summer-wet regions
Mediterranean basin
In the summer-dry regions south of the Pyrenees and Alps, and
including North Africa. This is not geographically separable from
Central Europe.
Danthonioid biogeography: ecology and history. Appendix S2. Page 5
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