Biografia Barker conseguì la laurea presso la University of Witwatersrand di Johannesburg (Sudafrica) e il dottorato di ricerca presso la Università di Cape Town di Città del Capo, con una tesi sulla sistematica delle piante erbacee sul sito della Rhodes University.
Dopo il periodo di dottorato, trascorse circa un anno come frequentatore post-doc presso la University of the Western Cape, dove, collaborando con Derek Keats, apprese a sviluppare e applicare le tecniche molecolari, in particolare dedicandosi allo studio delle alghe rosse coralline.
Successivamente trascorse 8 mesi a Sydney, Australia, come "ricercatore ospite" presso i Royal Botanic Gardens. A Sydney collaborò con il Dott. Peter Henry Weston sulla filogenia a partire dal livello di famiglia per la famiglia Proteaceae.
Nel 1997 ottenne la nomina a lettore presso la Rhodes University di Grahamstown (Sud Africa), dapprincipio a contratto e, poco tempo dopo, come membro dello staff a tempo indeterminato. Nel 2012 è professore ordinario e Direttore del Dipartimento di Botanica in questa università.
Pubblicazioni Di seguito si riportano le pubblicazioni più recenti di Barker (dal 2005 al 2012). 2005 Dold, A.P., Hammer, S. & Barker, N.P. (2005). Leaves of Grass: A taxonomic revision of the genus Bergeranthus Schwantes (Aizoaceae). Haseltonia 11: 78-97. Linder, H.P. and Barker, N.P. (2005). From Nees to now – changing questions in the systematics of the grass subfamily Danthonioideae. Nova Acta Leopoldina 92, Nr 342: 29-44. McKenzie, R.J., Barker, N.P., Samuels, J., Muller, E.M. & Skinner, A. (2005). Morphology of cypselae in subtribe Arctotidinae (Compositae–Arctotideae) and its taxonomic implications. Annals of the Missouri Botanic Garden 92: 569-594. Barker, N.P. (2005) A review and survey of amphicarpy, basicarpy and geocarpy in the African and Madagascan flora. Annals of the Missouri Botanic Garden 92: 445-462. Barker, N.P., Von Senger, I., Howis, S., Zachariades, C. & Ripley, B.S. (2005) Plant phylogeography based on rDNA ITS sequence data: two examples from the Asteraceae. In: Plant species-level systematics: New perspectives on patterns and process. Edited by F.T. Bakker, L.W. Chatrou, B. Gravendeel & P.B. Pelser. Gantner Verlag, Ruggell [Regnum Vegetabile 142: 217-244]. 2006 McKenzie, R.M., Herman, P.J. & Barker, N.P. (2006). Asteraceae. Arctotis decurrens (Asteraceae: Arctotideae), the correct name for A. merxmuelleri and A. scullyi. Bothalia 36: 171-173. Weston, P.H. and Barker, N.P. (2006). A new suprageneric classification of the Proteaceae, with an annotated checklist of genera. Telopea 11: 314-344. McKenzie, R.J., Barker, N.P., Muller, E.M. & Karis, P.O. (2006) Phylogenetic relationships and generic delimitation in subtribe Arctotidinae (Asteraceae: Arctotideae) inferred by DNA sequence data from ITS and five chloroplast regions. American Journal of Botany 93(8): 1222-1235. McKenzie, R.J., Mitchell, S.D. and Barker, N.P. (2006). A new species of Arctotis (Compositae, Arctotideae) from kommetjie grassland in Eastern Cape Province, South Africa. Botanical Journal of the Linnaean Society 151: 581-588. Verboom, G.A., Ntsohi, R. & N.P. Barker. (2006). Molecular phylogeny of African Rytidosperma-affiliated Danthonioid grasses reveals generic polyphyly and convergent evolution in spikelet morphology. Taxon 55: 337-348. Teske, P.R., McQuaid, C.D., Froneman, P.W. & Barker, N.P. (2006). Impacts of marine biogeographic boundaries on phylogeographic patterns of three South African estuarine crustaceans. Marine Ecological Progress Series 314: 283-293. Robertson, M.P. & Barker, N.P. (2006). A technique for evaluating species richness maps generated from collections data. South African Journal of Science 102: 77-84. Ramdhani, S., Barker, N.P. & Baijnath, S. (2006) Phylogenetics of the genus Kniphofia Moench (Asphodelaceae).Pp 559-570. In: Ghazanfar, S.A. & Beentje, H.J. (eds), Taxonomy & Ecology of African plants: their conservation and sustainable use. Royal Botanic Gardens, Kew. (Proceedings of the 17th AETFAT conference, held in Addis Ababa, Ethiopia, 22nd – 26th September 2003). 2007 McKenzie, R.J. & Barker, N.P. (2007). Proposal to conserve Venidium semipapposum (Arctotis semipapposa) against Arctotis scabra (Asteraceae, Arctotideae). Taxon 56(4): 1300-1301. Barker, N.P. & Fish, L. (2007). Rare and infrequent southern African grasses: assessing their conservation status and understanding their biology. Biodiversity & Conservation 16: 4051-4079. Teske, P.R., Papadopoulos, I., Newman, B.K., McQuaid, C.D. & Barker, N.P. (2007). Climate change, genetics or human choice: why the shells of mankind's earliest ornament were larger during the Pleistocene than during the Holocene. PLoS ONE . Teske, P.R., Froneman, P.W., Barker, N.P. & McQuaid, C.D. (2007). Phylogeograpic structure of the caridean shrimp Palaemon peringueyi in South Africa: more evidence for intraspecific units associated with marine biogeographic provinces. African Journal of Marine Science 29(2): 253-258. Barker, N.P., Weston, P.H., Rutschmann, F & Sauquet, H. (2007). Molecular dating of the “Gondwanan” plant family Proteaceae is only partially congruent with the timing of Gondwanan break-up. Journal of Biogeography: 34: 2012-2027. Teske, P.R., Hamilton, H., Mattheee, C.A., & Barker, N.P. (2007). Signatures of seaway closures and founder dispersal in the phylogeny of a circumglobally distributed seahorse lineage. BMC Evolutionary Biology 7: 138. https://www.biomedcentral.com/1471-2148/7/138 Teske, P.R., Zardi, G.I., McQuaid, C.D., Papadopoulos, I., Barker, N.P., Edkins, M.T. & Griffiths, C.L. (2007). Implications of life history on genetic structure and migration rates of southern African coastal invertebrates: planktonic, abbreviated and direct development. Marine Biology 152: 697-711. Teske, P.R., Oosthuizen, A., Papadopoulos, I., Barker, N.P. (2007). Phylogeographic structure of Octopus vulgaris in South Africa revisited: identification of a second lineage near Durban harbour. Marine Biology 151: 2119-2112. Price, B., Barker, N.P. & Villet, M.H. (2007). Patterns and processes underlying evolutionary significant units in the Platypleura stridula L. species complex (Hemiptera: Cicadidae) in the Cape Floristic Region, South Africa. Molecular Ecology 16: 2574-2588. Teske, P.R., Barker, N.P. & McQuaid, C.D. (2007). Lack of genetic differentiation between four sympatric southeast African intertidal limpets: Phenotypic plasticity in a single species? Journal of Molluscan Studies 73: 223-228. ONLINE doi: 10.1093/mollus/eym012. Zardi, G.I., McQuaid, C.D., Teske, P.R., and Barker, N.P. (2007) Unexpected genetic structure of indigenous (Perna perna) and invasive (Mytilus galloprovincialis) mussel populations in South Africa. Marine Ecological Progress Series 337: 135-144. Barker, N.P., Galley, C., Verboom, A.G., Mafa, P., Gilbert, M. & Linder, H.P. (2007). The phylogeny of the austral grass subfamily Danthonioideae: Evidence from multiple data sets. Plant Systematics and Evolution 264: 135-156. 2008 Teske, P.R., Papadopoulos, I., Newman, B.K., Dworschak, P.C., McQuaid, C.D. & Barker, N.P. (2008). Oceanic dispersal barriers, adaptation and larval retention: an assessment of potential factors maintaining a phylogeographic break between sister lineages of an African prawn. BMC Evolutionary Biology 8: 341. McKenzie, R.J., Hjertson, M. & Barker, N.P. (2008). Typification of the name Arctotis plantaginea and names in the Arctotis semipapposa species complex (Asteraceae, Arctotideae). Taxon 57: 1341-1346. Nicastro, K.R., Zardi, G.I., McQuaid, C.D., Teske, P.R. & Barker, N.P. (2008). Coastal topography drives genetic structure in marine mussels. Marine Ecological Progress Series 368:189-195. De Wet, L.A. Barker, N.P. & Peter, C.I. (2008). The long and the short of gene flow and reproductive isolation: Inter Simple Sequence Repeat (ISSR) markers support the recognition of two floral forms in Pelargonium reniforme (Geraniaceae). Biochemical Systematics & Ecology 36: 684-690. McKenzie, R.J. & Barker, N.P. (2008). Radiation and biogeography of the predominantly southern African subtribe Arctotidinae (Asteraceae: Arctotideae). Molecular Phylogenetics & Evolution 49: 1-16. Bownes, S., Barker, N.P. & McQuaid, C.D. (2008). Morphological identification of mussel settlers and post-larvae from the coast of South Africa. African Journal of Marine Science 30: 233-240. Ramdhani, S., Barker, N.P. & Baijnath, H. (2008). Exploring the Afromontane centre of endemism: Kniphofia Moench (Asphodelaceae) as a floristic indicator. Journal of Biogeography 35: 2258-2273. Pirie, M.D., Humphreys, A.M., Galley, C., Barker, N.P., Verboom, G.A., Orlovich, D., Draffin, S.J., Lloyd, K., Baeza, C.M., Negritto, M., Ruiz, E., Cota Sanchez, J.H., Reimer, E. & Linder, H.P. (2008). A supermatrix approach resolves phylogenetic relationships in Danthonioid grasses. Molecular Phylogenetics and Evolution 48: 1106-1119. Kelly, C.M.R., Barker, N.P., Villet; M.H., Broadley, D.G. & Branch, W.R. (2008). The snake family Psammophiidae (Reptilia: Serpentes): Phylogenetics and species delimitation in the African sand snakes (Psammophis Boie, 1825) and allied genera. Molecular Phylogenetics & Evolution 47: 1045-1060. McKenzie, R.J., Hjertson, M. & Barker, N.P. (2008). Typification of the name Arctotis lanata and those of some southern African Haplocarpha species (Asteraceae, Arctotideae). Taxon 57(2): 612-614. Buys, M.H. Janse van Rensburg, L.-L., Mienie, C.M.S., Barker, N.P., Burgoyne, P. Mills, L., Van Rensburg, L. & Hartmann, H. (2008). Applying AFLPs in Aizoaceae: The Delosperma herbeum complex as a case study. Biochemical Systematics & Ecology 36: 92-100. 2009 Pirie, M.D., Humphreys, A.M., Barker, N.P. & Linder, H.P. (2009). Reticulation, data combination, and inferring evolutionary history: an example from Danthonioideae (Poaceae). Systematic Biology 58: 612-628. Ramdhani, S., Barker, N.P. & Baijnath, H. (2009). Rampant non-monophyly of species in Kniphofia Moench (Asphodelaceae) suggests a recent Afromontane radiation. Taxon 58:1141-1152. Barker, N.P., Howis, S., Nordenstam, B., Källersjö, M, Eldenas, P., Griffioen, C. & Linder, H.P. (2009) Nuclear and chloroplast DNA-based phylogenies of Chrysanthemoides Tourn. ex Medik (Calenduleae; Asteraceae) reveal extensive incongruence and generic paraphyly, but support the recognition of infraspecific taxa in C. monilifera. South African Journal of Botany. 75: 560-572. Teske, P.R., McLay, C.L Sandoval-Castillo, J., Papadopoulos, I., Newman, B.K., Griffiths, C.L., McQuaid, C.D., Barker, N.P., Borgonie, G. & Beheregaray, L.B. (2009). Tri-locus sequence data reject a “Gondwanan origin hypothesis” for the African/South Pacific crab genus Hymenosoma. Molecular Phylogenetics & Evolution 53: 23-33. Schrire, B.D., Lavin, M., Barker, N.P. & Forest, F. (2009). Phylogeny of the tribe Indigofereae (Leguminosae – Papilionoideae): Geographically structured more in succulent-rich and temperate settings than in grass-rich environments. American Journal of Botany 96: 816-852. Teske, P.R., Winker, H., McQuaid, C.D. & Barker, N.P. (2009). A tropical/subtropical biogeographic disjunction in southeastern Africa separates two Evolutionarily Significant Units of an estuarine prawn. Marine Biology 156: 1265-1275. Howis, S., Barker, N.P. & Mucina, L. (2009). Globally grown, but poorly known: Species limits and biogeography of Gazania Gaertn. (Asteraceae) inferred from chloroplast and nuclear DNA sequence data. Taxon58: 871-882. Clark, V.R., Barker, N.P. & Mucina, L. (2009). The Sneeuberg: A new centre of floristic endemism on the Great Escarpment, South Africa. South African Journal of Botany 75: 196-238. (This paper was awarded the Compton prize for the best paper published in this journal in 2009).