Karyological analysis of the five native Macaronesian &lt;i&gt;Festuca&lt;/i&gt; (Gramineae) grasses supports a distinct diploid origin of two schizoendemic groups

Miguel Menezes De Sequeira,Juan Viruel,Arnoldo Santos-Guerra,Pilar Catalán,Antonio Díaz-Pérez

doi:10.3989/ajbm.2196

Karyological analysis of the five native Macaronesian <i>Festuca</i> (Gramineae) grasses supports a distinct diploid origin of two schizoendemic groups

Miguel Menezes De Sequeira, Juan Viruel + Show 3 more

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https://doi.org/10.3989/ajbm.2196

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Abstract

A karyological analysis has been conducted of all five native Macaronesian Festuca grasses belonging to fine-leaved F. subg. Festuca sect. Aulaxyper and broad-leaved F. subg. Drymanthele sect. Phaeochloa Loliinae lineages. Chromosomal analyses were made in 30 plants corresponding to 17 populations of the fineleaved F. agustinii, F. jubata, F. francoi and F. petraea and 2 populations of the broad-leaved F. donax . All counts except one tetraploid count were diploids, showing 2 n = 14 chromosomes. Diploidy was confirmed for the robust F. donax , nested within a clade of relict ancestral fescues as reported in recent phylogenetic studies, and was also found in the more slender F. agustinii, F. jubata, F. francoi and F. petraea , which are basal to a recently evolved clade of polyploid red fescues. Karyotypes of the two groups are however distinct, with broad-leaved F. donax showing larger and more regular chromosomes and all four fine-leaved taxa showing smaller and more irregular submetacentric chromosomes. Our karyological data indicate that these two groups of diploid fescues correspond to distinct schizoendemics which apparently originated at different times after independent continental colonizations of Macaronesia.

Highlights

The Macaronesian region is one of the major hot-spots of plant diversity in oceanic isles (Humphries, 1979; Hansen & Sunding, 1993; Francisco-Ortega & al., 1996; Carine & al., 2004), most of the Poaceae genera present in the region show a relatively low number of Macaronesian endemics (Cope, 1994; Santos-Guerra, 1999; Borges & al., 2005)
Our extensive survey confirms previous diploid counts reported for the Madeiran F. jubata (Dalgaard, 1986) and F. donax (Malik & Thomas, 1966) and for the Azorean F. petraea (Devesa & Gómez, 1988)
Our karyological analysis conducted in individuals from different islands and populations of the five native Macaronesian Festuca indicate that these endemic taxa are mostly diploid

Summary

Introduction

The Macaronesian region is one of the major hot-spots of plant diversity in oceanic isles (Humphries, 1979; Hansen & Sunding, 1993; Francisco-Ortega & al., 1996; Carine & al., 2004), most of the Poaceae genera present in the region show a relatively low number of Macaronesian endemics (Cope, 1994; Santos-Guerra, 1999; Borges & al., 2005). To other angiosperm groups that show a high range (8-63) of oceanic taxa (e.g. Argyranthemum Webb, Echium L., Micromeria Benth., Sonchus L., Tolpis Adans., several genera of the family Crassulaceae –Aeonium Webb & Berthel., including Greenovia Webb & Berthel., Aichryson Webb & Berthel., Monanthes Haw., among others–; summarized in Silvertown, 2004, and Carine & al., 2004), the Macaronesian grasses present a small range of endemic species per genus which vary from single species Beauv., Festuca L., Holcus L., Lolium L., Melica L., Phalaris L., Poa L.) (Hansen & Sunding, 1993; Cope, 1994; Santos-Guerra, 1999; Borges & al., 2005)

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