Species limits in Vachellia (Acacia) karroo (Mimosoideae: Leguminoseae): Evidence from automated ISSR DNA “fingerprinting”

Vachellia karroo (Hayne) Banfi & Galasso, previously known as Acacia karroo Hayne, is a very common woody species in South Africa, and displays a large amount of morphological and architectural variation. Previous morphological studies have provided evidence to support the recognition of a number of segregate species, but this has not been supported by early protein electrophoresis studies. Genetic variability of the species throughout South Africa was examined by means of the Inter-Simple Sequence Repeat (ISSR) DNA “fingerprinting” to determine whether there is any genetic structure that correlates to the morphological diversity. Based upon 33 samples from across the South African distribution of this species, we found no evidence for any genetic structuring, suggesting the species is one panmictic entity. The existence of morphologically discrete varieties in light of this genetic finding is difficult to explain, and perhaps the species ought to be considered as an ochlospecies. A scenario whereby the various morphotypes evolved in refugia during previous climates followed by subsequent expansion and introgression during the current interglacial may explain this conundrum. Alternatively, the evolution of the morphotypes has been recent and rapid, and the genetic variation observed here represents the ancestral gene pool that has not yet undergone lineage sorting as a consequence of isolation.

[1]  P. Brain.  Leaf peroxidase types in Acacia karroo. Geographical distribution and influence of the environment , 1986 .

[2]  F. González,et al.  The biological monograph : the importance of field studies and functional syndromes for taxonomy and evolution of tropical plants , 1998 .

[3]  T. Chiang,et al.  Strong genetic differentiation of the East-Himalayan Megacodon stylophorus (Gentianaceae) detected by Inter-Simple Sequence Repeats (ISSR) , 2005, Biodiversity & Conservation.

[4]  S. Milton,et al.  Dispersal of Seeds as Nest Material by Birds in Semiarid Karoo Shrubland , 1990 .

[5]  M. F. Miller.  Dispersal of Acacia seeds by ungulates and ostriches in an African savanna , 1996, Journal of Tropical Ecology.

[6]  D. Labuda,et al.  Genome fingerprinting by simple sequence repeat (SSR)-anchored polymerase chain reaction amplification. , 1994, Genomics.

[7]  M. Roose,et al.  Identification of closely related citrus cultivars with inter-simple sequence repeat markers , 1997, Theoretical and Applied Genetics.

[8]  H. Ballard,et al.  Inferring nativity and biogeographic affinities of central and marginal populations of Froelichia floridana (Amaranthaceae) from Inter-Simple Sequence Repeat (ISSR) markers1 , 2002 .

[9]  K. C. Palgrave.  Trees of Southern Africa , 1977 .

[10]  P. Ranjekar,et al.  Identification of inter simple sequence repeat (ISSR) markers associated with seed size in wheat , 2001, Theoretical and Applied Genetics.

[11]  D. Ward,et al.  Phenotypic plasticity and local adaptation in two extreme populations of Acacia karroo , 2008 .

[12]  Shilong Chen,et al.  ISSR analysis of genetic diversity of the Qinghai-Tibet Plateau endemic, Rhodiola chrysanthemifolia (Crassulaceae) , 2007 .

[13]  R. Lande.  Adaptation to an extraordinary environment by evolution of phenotypic plasticity and genetic assimilation , 2009, Journal of evolutionary biology.

[14]  N. Blaum,et al.  Rodent-mediated dispersal of Acacia seeds in Kalahari savannah rangelands – implications for bush encroachment , 2011 .

[15]  M. Pigliucci,et al.  Phenotypic plasticity and evolution by genetic assimilation , 2006, Journal of Experimental Biology.

[16]  Ang Li,et al.  Genetic Variation and Clonal Diversity of Psammochloa villosa (Poaceae) Detected by ISSR Markers , 2001 .

[17]  T. O’Connor.  Acacia karroo invasion of grassland: environmental and biotic effects influencing seedling emergence and establishment , 1995, Oecologia.

[18]  P. Abbot.  Individual and population variation in invertebrates revealed by Inter-simple Sequence Repeats (ISSRs) , 2019 .

[19]  D. Huson,et al.  Application of phylogenetic networks in evolutionary studies. , 2006, Molecular biology and evolution.

[20]  Salhi-Hannachi Amel,et al.  Inter-Simple Sequence Repeat fingerprints to assess genetic diversity in Tunisian fig (Ficuscarica L.) germplasm , 2004, Genetic Resources and Crop Evolution.

[21]  W. Bond,et al.  Growing tall vs growing wide: tree architecture and allometry of Acacia karroo in forest, savanna, and arid environments , 2003 .

[22]  E. Robbrecht,et al.  Chorology, Taxonomy and Ecology of the Floras of Africa and Madagascar , 1998 .

[23]  Nils Arrigo,et al.  Evaluating the impact of scoring parameters on the structure of intra-specific genetic variation using RawGeno, an R package for automating AFLP scoring , 2009, BMC Bioinformatics.

[24]  I. Godwin,et al.  Application of inter simple sequence repeat (ISSR) markers to plant genetics , 1997, Electrophoresis.

[25]  Fang Chen,et al.  ISSR Analysis of the Genetic Diversity of the Endangered Species Sinopodophyllum hexandrum (Royle) Ying from Western Sichuan Province, China , 2006 .

[26]  X. Gong,et al.  ISSR variation in the endemic and endangered plant Cycas guizhouensis (Cycadaceae). , 2004, Annals of botany.

[27]  M. E. Mort,et al.  The utility of automated analysis of inter-simple sequence repeat (ISSR) loci for resolving relationships in the Canary Island species of Tolpis (Asteraceae). , 2006, American journal of botany.

[28]  F. Bakker,et al.  Reconstructing patterns of reticulate evolution in angiosperms: what can we do? , 2005 .

[29]  Daniel H. Huson,et al.  SplitsTree: analyzing and visualizing evolutionary data , 1998, Bioinform..

[30]  W. Bond,et al.  Palaeoclimate-induced range shifts may explain current patterns of spatial genetic variation in renosterbos (Elytropappus rhinocerotis, Asteraceae) , 2007 .

[31]  M. C. Rutherford,et al.  The vegetation of South Africa, Lesotho and Swaziland. , 2006 .

[32]  D. Ward.  Population differentiation in a purported ring species, Acacia karroo (Mimosoideae) , 2011 .

[33]  K. Hassel,et al.  The use of inter simple sequence repeats (ISSR) in bryophyte population studies , 2003 .

[34]  D. Irwin,et al.  The role of phenotypic plasticity in driving genetic evolution , 2003, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[35]  M. Chase,et al.  Silica gel: An ideal material for field preservation of leaf samples for DNA studies , 1991 .

[36]  J. Hamrick,et al.  Factors influencing levels of genetic diversity in woody plant species , 1992, New Forests.

[37]  S. Archak,et al.  Comparative assessment of DNA fingerprinting techniques (RAPD, ISSR and AFLP) for genetic analysis of cashew (Anacardium occidentale L.) accessions of India. , 2003, Genome.

[38]  E. Pahlich,et al.  A rapid DNA isolation procedure for small quantities of fresh leaf tissue , 1980 .

[39]  I. D. Paterson,et al.  Using molecular methods to determine the origin of weed populations of Pereskia aculeata in South Africa and its relevance to biological control. , 2009 .

[40]  D. Downie,et al.  Genetic diversity of introduced populations of the water hyacinth biological control agent Eccritotarsus catarinensis (Hemiptera: Miridae). , 2011 .

[41]  R. Dyer.  Acacia karroo in Southern Africa , 1971 .

[42]  Q. Xiang,et al.  Assessing hybridization in natural populations of Penstemon (Scrophulariaceae) using hypervariable intersimple sequence repeat (ISSR) bands , 1998, Molecular ecology.

[43]  N. Smit.  Guide to the acacias of South Africa. , 1999 .

[44]  T. Mondal.  Assessment of genetic diversity of tea (Camellia sinensis (L.) O. Kuntze) by inter-simple sequence repeat polymerase chain reaction , 2002, Euphytica.