Abstract Detail



Biogeography

Martin-Bravo, Santiago [1], Márquez-Corro, José Ignacio [2], Ford, Kerry A. [3].

The genus Carex (Cyperaceae) in New Zealand: a southern hemisphere diversity hotspot in a boreotemperate genus.

Carex is a megadiverse genus with about 2000 species of almost cosmopolitan distribution, which originated and is especially diversified in the temperate and cold regions of the Northern Hemisphere, although different lineages have colonized the Southern Hemisphere. With its prolonged isolation New Zealand has disparately high species richness and endemicity in some plant groups. Carex is one of these groups and is the second largest angiosperm genus after Veronica with c. 116 species (87% endemic). In the context of a newly available molecular phylogeny of Carex, the New Zealand islands have been recurrently colonized by different lineages via long distance dispersal, with five of the six Carex subgenera and 16 sections present. Timing of colonizations range between 7,72 and 0,36 mya. Two lineages in particular (sects. Echinochlaenae and Uncinia) account for much of the diversity (>70%, c. 82 species), suggesting evolutionary radiation processes during their differentiation, which is in agreement with molecular evidence, wide ecological and morphological diversity and relatively uniform chromosome numbers. Species of Carex sect. Echinochlaenae occur from coast to alpine and are characteristic of open habitats: oligotrophic wetlands, turfs, dunes, and grassland/herbfields, including calcareous and ultramafic substrates. Species of Carex sect. Uncinia are primarily of forest and alpine grassland habitats. The diversification of these groups could have been correlated with the cooling climate of the late Neogene (7.5-4.5 mya) and the emergence of open habitats and the initiation of uplift of the southern alps 4-3 mya onwards creating an expansive alpine area by 1.2 mya. Interesting biogeographic patterns are revealed by the distribution of non-endemic species/groups, with disjunctions found between Southern Hemisphere landmasses, Northern vs Southern hemisphere, bipolar, Australia-Tasmania-New Zealand and East Asian-Pacific. On the other hand, restricted endemics shed light on some New Zealand’s putatively important areas for Carex speciation, like the Chatham Islands or the Northwestern mountains of the South Island. Some morphological features of New Zealand’s Carex are also remarkable, like the presence of acaulescence or very long caulescence, a tall tussock-like habit, or the unique presence of red-leaved species in four different lineages, a feature that has been put forward as a possible adaptation to herbivory by birds including the extinct moas.


1 - Universidad Pablo de Olavide, Biología Molecular e Ingeniería Bioquímica, Ctra. de Utrera km 1, Seville, Seville, 41013, Spain
2 - Royal Botanic Gardens, Kew, Herbarium, Kew, Richmond, London, TW9 3AQ, UK
3 - Manaaki Whenua – Landcare Research, Systematics, 54 Gerald Street, Lincoln, 7698, New Zealand

Keywords:
biogeography
Carex
New Zealand
Southern Hemisphere
evolutionary radiation
long distance dispersal.

Presentation Type: Oral Paper
Session: BIOG III, Biogeography III
Location: Lupine/Hilton
Date: Wednesday, July 27th, 2022
Time: 4:15 PM(EDT)
Live or Virtual Virtual
Number: BIOG III010
Abstract ID:420
Candidate for Awards:None


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