Microsporogenesis and meiotic abnormalities in the hybrid complex of Phlomis composita (Lamiaceae)

Abstract

The extent of chromosome structural differences such as permanent translocations and paracentric inversions has been studied in the hybrid complex of Phlomis composita and its putative parental taxa P. lychnitis and P. crinita . They are detected as meiotic abnormalities during microsporogenesis. In total, 117 plants from 19 populations in Andalusia (southern Spain) and Levante (eastern Spain) were studied for ploidy level, chromosome clumping, multivalent or univalent formation, late bivalent disjunction with bridges, chromatin bridges and fragments, irregular polysporads and variable pollen size. All individuals had the diploid chromosome number 2 n = 20, with no significant difference in the frequencies of the above meiotic abnormalities either at taxon or population levels. However, very different frequencies were observed on the regional scale between populations in Andalusia and Levante. The results are discussed within the theoretical framework of homoploid hybrid or recombinational speciation.

Contrasting nuclear‐plastidial phylogenetic patterns in the recently diverged IberianPhlomis crinitaandP. lychnitislineages (Lamiaceae)

“…Second, extensive hybridization and introgression between P. crinita subsp. malacitana and P. lychnitis seems to occur based on the patterns of meiotic abnormalities (Aparicio & Albaladejo, 2003) and morphological variability in Andalusian populations where both taxa are sympatric (Albaladejo & al., 2004). In fact, the absence of nonpolymorphic ITS sequences in the eight studied samples of P. crinita subsp.…”

“…malacitana and P. lychnitis. One such process would be facilitated by the frequency of hybridization detected among the Iberian Phlomis (Aparicio & Albaladejo, 2003;Albaladejo & al., 2004) and would also be compatible with the experimental evidence that crosses of those two taxa with P. lychnitis as maternal parent are more viable than the reciprocal (Albaladejo & Aparicio, unpubl.). Taking this evidence into account, it would be conceivable that haplotypes shared by P. crinita subsp.…”

“…All Iberian taxa are diploid (2n = 20), and a higher frequency of meiotic irregularities (i.e., univalents and multivalents, chromatinic bridges, chromosome clumping and polysporads) have been found in mixed populations in Andalusia as compared to those in Levante. These results have been interpreted as the outcomes of a higher frequency of hybridization and introgression in Andalusia as compared to Levante (Aparicio & Albaladejo, 2003).…”

Precisiones nomenclaturales en <em>Phlomis</em> × <em>composita</em> Pau <em>(Lamiaceae)</em>

“…En ocasiones el cruce entre ambas especies da lugar a un enjambre de híbridos con un amplio espectro de formas, que han sido tratadas con diferentes rangos taxonómicos según los autores. Esta hibridación ha sido motivo de diferentes estudios a lo largo de los últimos años (Mateu, 1986;Aparicio et al, 2000;Aparicio & Albaladejo, 2003;Albaladejo et al, 2004Albaladejo et al, , 2005Albaladejo & Aparicio, 2007), en los que se han tratado diferentes aspectos relacionados con la compleja taxonomía que surge del cruce entre las diferentes entidades taxonómicas reconocidas dentro de P. crinita y P. lychnitis.…”

“…malacitana de Pau de P. crinita. Esta categoría taxonómica para el híbrido de Pau ha sido usualmente empleada en posteriores trabajos que se ocupan de este taxon (Aparicio, 1997;Aparicio & Albaladejo, 2003;Albaladejo et al, 2004). No obstante, en la actualidad se reconoce como más apropiado la utilización del rango subespecífico para los dos mestos incluidos dentro de P. crinita (Cabezudo et al, 1991;Navarro et al 2002;Albaladejo et al, 2004;Navarro, 2009;Morales, 2010), lo que implica considerar como nothosubespecie el híbrido descrito por Pau para el término de Tous.…”