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214

I S S U E S E V E N

H O R I Z O N 2 0 2 0 P R O J E C T S : P O R TA L

www.horizon2020projects.com

P R O F I L E

S O C I E TA L C H A L L E N G E S : C L I M AT E A C T I O N

IN

the working group of Professor Eberhard Fischer

different organisms are studied, e.g. lichens, fresh

water red algae, bryophytes and various flowering

plants such as Linderniaceae, gingers or orchids. Here, the

fascinating studies on African balsams (

Impatiens)

are addressed.

Impatiens –

understanding past climate change to

predict future climate change in Africa

Impatiens

are especially diverse in tropical Africa and

Madagascar. They thrive in montane regions that probably served

as rainforest refugia during periods of excessive drought

throughout the Pleistocene. Their actual distribution is mainly a

result of climate change and oscillation of forest cover during the

last one million years. During the periods of glaciation in the

northern hemisphere, the climate in Africa became cool and dry.

Rainforests were restricted to small refugial areas. The Congo

basin was mostly devoid of forests.

Many taxa of

Impatiens

are narrow local endemics, just restricted

to a single forest or mountain. A prominent example is

Impatiens

teitensis

Grey-Wilson from the Taita Hills/Kenya, only known from

the summit of Mount Ngangao. Together with S Janssens and T

Stévart (Janssens

et al.

(2010):

Taxon

59: 1508-1518) it could

be shown that the divergence of two other local endemics,

Impatiens issembei Janssens, Stévart & Eb. Fisch., and

I. wilkesiana Stévart, Janssens & Eb. Fisch., probably

occurred at

0.96 Ma ago, which corresponds to increasingly drier periods.

The once continuous ancestral population was fragmented into

two sister populations restricted to two forest refuges in Gabon,

the Chaillu mountains and the Monts de Cristal, where allopatric

speciation played a key role in the origin and diversification of the

present-day

Impatiens

species. Similar scenarios can be

observed all over tropical Africa, e.g. in the Albertine Rift.

Here, three closely related species –

I. runssorensis

Warb, from the

Rwenzori Mountains (DR Congo/Uganda),

I. nyungwensis

Eb. Fisch.

et al.,

from the Nyungwe massif/Rwanda, and

I. bururiensis

Grey-

Wilson, from the Bururi massif, Burundi – probably evolved from a

common ancestor where the population was fragmented and the

three species evolved in the abovementioned forest refuges.

The species of

Impatiens

obviously evolved rapidly. Thus, the

whole diversity of balsams in Madagascar (

c.

260 species)

evolved from one common ancestor within one million years. Here,

even higher rates of diversification and speciation occurred, and

nearly 99% of all species were restricted to small areas or even a

single mountain. The key feature of this radiation is presently not

known. Research, including molecular methods as well as field

work on pollination, is required to understand this phenomenon.

By understanding the evolution of

Impatiens,

which is mainly a

result of past climate change, we will be able to understand and

predict future climate change.

Professor Dr Eberhard Fischer

Botany and Biodiversity

Department of Biology, Institute for IntegratedNatural Sciences

University of Koblenz-Landau, Campus Koblenz

te l :

+49 (0)2612872224

efischer@uni-koblenz.de http://www.uni-koblenz- landau.de/de/koblenz/fb3/ifin/abteilung-biologie/ag-botani k/mitarbeitende/eberhard-fischer

Professor Eberhard Fischer, from the University of Koblenz-Landau, highlights the

importance of understanding the evolution of

Impatiens

as an indicator for

climate change

Balsams and climate change

Impatiens nyungwensis

Impatiens bururiensis