[Botany • 2019] Natural Hybridization – Recombination – An ever-ongoing Process

Figure 5. Spathe limbs of the Cryptocoryne crispatula Engl. complex. – A. C. crispatula var. yunnanensis (H.Li) H.Li & N.Jacobsen, Ban Phon Gun Nam Ken, central Laos; B. C. crispatula var. crispatula (albida like), Nam Cheng, central Laos;  M. C. crispatula var. flaccidifolia N.Jacobsen, Khao Sok River, PEN Thailand;  Q. C. albida (crispatula like), 3 Pagoda Pass, SW Thailand.  Scale 2 cm.
Figure 1. Cryptocoryne albida Parker on a sandbank and C. crispatula Engl. var. flaccidifolia N.Jacobsen submerged in the river; Khao Sok River, S Thailand.

in Jacobsen & Ørgaard, 2019. 

  DOI: 10.20531/tfb.2019.47.1.05

ABSTRACT

Exemplified by studies of the SE Asian genus Cryptocoryne (Araceae) we provide evidence that: 1) interspecific hybridization is an everongoing process, and introgression and gene exchange takes place whenever physically possible throughout the region; 2) artificial hybridization experiments confirm that wide crosses are possible in a large number of cases; 3) rivers and streams provide numerous, diverse habitats for Cryptocoryne diaspores to settle in; 4) the changes in habitats caused by recurrent glaciations resulting in numerous splitting and merging of populations facilitates hybridization and segregation of subsequent generations; 5) hybridization is a major driving element in speciation; 6) populations are the units and stepping stones in evolution – not the species.

KEYWORDS:  Araceae, Chromosome numbers, Cryptocoryne, hybridization, evolution

Figure 3. Spathe limbs of different Cryptocoryne species.
 A. C. usteriana Engl., Philippines; B. C. nevillii Hook.f., Sri Lanka; C. C. walkeri Schott, Sri Lanka;  D. C. matakensis Bastm. et al., Anambas Islands; E. C. bangkaensis Bastm., South Sumatera Province and the Islands Bangka and Belitung; F. C. alba De Wit, Sri Lanka; G. C. griffithii Schott, southern Peninsular Malaysia, Singapore, Riau Islands and southern Central Kalimantan; H. C. idei Budianto, Central Kalimantan. Scale bar 2 cm.

Figure 5. Spathe limbs of the Cryptocoryne crispatula Engl. complex. – A. C. crispatula var. yunnanensis (H.Li) H.Li & N.Jacobsen, Ban Phon Gun Nam Ken, central Laos; B. C. crispatula var. crispatula (albida like), Nam Cheng, central Laos;  M. C. crispatula var. flaccidifolia N.Jacobsen, Khao Sok River, PEN Thailand;  Q. C. albida (crispatula like), 3 Pagoda Pass, SW Thailand.  Scale 2 cm.
Figure 1. Cryptocoryne albida Parker on a sandbank and C. crispatula Engl. var. flaccidifolia N.Jacobsen submerged in the river; Khao Sok River, S Thailand.

Niels Jacobsen and Marian Ørgaard. 2019. Natural Hybridization – Recombination – An ever-ongoing Process. Thai Forest Bulletin (Botany). 47(1); 19-28.  DOI: 10.20531/tfb.2019.47.1.05