Flora Montiberica 70: 80-86 (III-2018). ISSN: 1138-5952, edic. digital: 1988-799X REPORT OF TWO SPONTANEOUS, RARE PHENOTYPIC TRAITS IN THE GENUS PHILLYREA L. José Luis MEDINA-GAVILÁN SOCEAMB, Sociedad de Estudios Ambientales. C/Perú, 4, 1ª planta. 41100-Coria del Río (Sevilla). [email protected] ABSTRACT: In this note, I document two previously unreported, spontane- ous and exceptionally rare phenotypic expressions affecting reproductive traits in adult plants of the Mediterranean genus Phillyrea (Oleaceae): (i) a morph with an abnormally elongated stigma and lobes transformed in two long branches (i.e. deeper-stigma phenotype), detected in a population of Phillyrea latifolia L. from NE Spain, and (ii) a morph with fruits lacking anthocyanins (i.e. colourless-fruit phenotype), in a population of Phillyrea angustifolia L. from SW Spain. Both phenotypes occurred at a very low frequency within their respective populations. Despite this, the novel traits acquired are discussed in an eco-evolutionary con- text, revealing their potential use as a study model, limited but suggestive, to test adaptive hypothesis in natural conditions. Keywords: phenotypic expression; adaptive value; anemophilous syndrome; selection mediated by frugivorous birds. RESUMEN: Descripción de dos caracteres fenotípicos, raros y espontáneos en el género mediterráneo Phillyrea L. En esta nota documento la presencia de dos expresiones fenotípicas desconocidas, espontáneas y excepcionalmente raras, que afectan a caracteres reproductivos en plantas adultas del género mediterráneo Phillyrea (Oleaceae): (i) un morfo con un estigma anormalmente largo y lóbulos transformados en dos ramas (i.e. fenotipo de estigma profundo), detectado en una población de Phillyrea latifolia L. en el noreste de España, y (ii) un morfo con frutos carentes de antocianinas (i.e. fenotipo de frutos sin pigmentación), en una población de Phillyrea angustifolia L. del suroeste español. Ambos fenotipos se manifestaron con muy baja frecuencia dentro de sus respectivas poblaciones. A pesar de ello, se discute la adquisición de estos nuevos caracteres en un contexto eco-evolutivo, reve- lando su uso potencial como modelo de estudio con el que explorar hipótesis adapta- tivas en condiciones naturales. Palabras clave: expresión fenotípica; valor adaptati- vo; síndrome anemófilo; selección mediada por aves frugívoras. INTRODUCTION sciences, both at the micro- (FERNÁNDEZ & al., 2006; DORMONT & al., 2009; ZIER- Novel phenotypic traits arising from MANN & al., 2009) and macroevolutionary any heritable source of biological varia- levels (BATEMAN & RUDDAL, 2006; tion are the substrate of all evolutionary RUDDAL & al., 2011). In this regard, field change in nature (WONG & HOURY, 2006). observation and recording of new pheno- Consequently, mechanistic and functional typic traits at local scale should not be approaches to the existence and/or underestimated, because of their value as maintenance of innovative phenotypic possible starting-point to explore evolu- forms within wild populations may have tionary processes in natural scenarios, be- an important significance in evolutionary yond experimental manipulation of mo- del-species in the laboratory. 80 J. L. MEDINA-GAVILÁN In this note, I report the existence of ma and exerted stamens with high pollen two spontaneous, rare phenotypic traits production, clearly adapted to anemoga- within the genus Phillyrea L. (Oleaceae), my (HERRERA, 1987); and blue drupes related to floral structure and fruit display with large seeds dispersed by birds (HE- respectively: (i) a morph with an anoma- RRERA, 1984). The most singular trait of lous stigma bifurcated in two long bran- Phillyrea species is their androdioecious ches, detected in Ph. latifolia (deeper-stig- nature, a rare, stable breeding system in ma phenotype, hereafter); and (ii) a morph which male and hermaphrodite individu- with fruits lacking anthocyanins, in als coexist within the same population Ph. angustifolia (colourless-fruit phenotype, (LEPART & DOMMÉE, 1992; ARONNE & hereafter). To my knowledge, none of these WILCOCK, 1994). phenotypic expressions have been described before (cf. DE JUANA, 2012). RESULTS AND DISCUSSION Phillyrea latifolia L. (deeper-stigma pheno- STUDY SPECIES type; fig. 1) Phillyrea L. is a circunmediterranean TARRAGONA: 31TCF3579. Vimbodí i Poblet, Prades Mountains, Valley of Torners, genus from an old lineage of miocenic Solera dels Torner (Natural Reserve Barranc origin, belonging to the olive-tree tribe del Tillar), 850 m a.s.l., at 25% south-facing (Oleaceae: Oleinae) (BESNARD & al., 2009; slope on district cambisol soil, 12-V-2005, J.L. HONG-WA & BESNARD, 2013). At pre- Medina-Gavilán. sent, taxonomy considers only 2-3 species Ordinarily, hermaphrodite flowers of within this genus: Ph. angustifolia L., Ph. latifolia have a short style terminated Ph. latifolia L. and, with controversy, by an elongate, bilobate stigma (<1 mm), Ph. media L. (FERRER-GALLEGO & al., whose length at maturity is almost half 2014). However, recent molecular studies that of the anthers just before their dehis- suggest its poly- or paraphyletic nature cence. Stigmatic lobes, though sometimes (HONG-WA & BESNARD, 2014), which not conspicuous, are clearly acute (fig. 2). will force to revise its taxonomy. In fact, it has been taken as one of the dif- Phillyrea species inhabit thermo- to ferential trait for this species (AMARAL meso-mediterranean forests and macchia FRANCO & ROCHA, 1972; ANDRÉS, 2012). formations (RIVAS-MARTÍNEZ & al., In Solera dels Torner, one individual 2002). Among woody flora from Mediter- with all its flowers bearing an abnormal ranean-type ecosystems, they present a set stigma was found within a dense forest of morpho-functional features associated community dominated by Quercus ilex L., in the so-called pre-Mediterranean syn- Phillyrea latifolia L. and Arbutus unedo L. drome (HERRERA, 1992; VERDÚ & al., (cf. OGAYA & al., 2015 for a more detailed 2003). So, they are phanerophytes show- description). The stigma was extraordinari- ing a deep root system, slow growth-rate ly long (=deep) -with a total length more from seed, long life-span and persistence than twice that of a typical one (2-5 mm)- after severe perturbation mediated by re- and bifurcated, resembling a pitchfork sprouting ability from subterranean buds (fig. 2). Likely, a mutation in a single (LIU (RUIZ-ROBLETO & VILLAR, 2005; VITA- & al., 2015) or a few (GOODWILLIE & al., LE & al., 2007); evergreen, sclerophyllous 2006) quantitative trait loci accounts for foliage, ecophysiologically well adapted the structural change on the trait ‘stigma- to avoid drought effects (GRATANI & depth’ in this rare phenotype. In any case, VARONE, 2004; SAURA-MAS & LLORET, female fertility at flower level (i.e. fruit- 2007); small nectarless flowers, with a re- set) was similarly comparable to the ordi- duced perianth, relatively prominent stig- nary phenotype. 81 Flora Montiberica 70: 80-86 (III-2018) ISSN 1138-5952 – eISSN 1988-799X Two spontaneous, rare phenotypic traits in the genus Phillyrea L. A surface of 1200 m2 containing 185 In short, this wild mutant could serve flowering trees of Ph. latifolia was surveyed to explore some of these interesting eco- on May 2005 in this zone, but no other indi- logical hypothesis in the frame of micro- vidual with this trait was detected. It reveals evolutionary processes for anemogamous the rarity of this morph. The population was long-lived species, despite the severe li- apparently hermaphrodite, without known mitation of having a single individual. presence of male individuals (69% hermaph- rodites, 31% unknown sex, n=268). Phillyrea angustifolia L. (colourless-fruit Phillyrea promotes xenogamy through phenotype; fig. 3) a sophisticated homomorphic diallelic SEVILLE: 29SQB4723. Aznalcázar, Monte self-incompatibility system, largely con- “Grupo ordenado de Aznalcázar” (SE-50001- served in Oleaceae (VERNET & al., 2016). AY), close to Cañada Real de los Isleños Thus, any functional trait conducive to (cuartel A, tramo III, subtramo e), 18 m a.s.l., on typic fragixeralf soil, 1-IX-2003, J.L. Me- maximize the collection efficiency of dina-Gavilán. compatible pollen is susceptible to be un- Ripen fruits of Phillyrea are purple to der natural selection for sexual success blackish-blue drupes, with anthocyanins (FRIEDMAN & BARRETT, 2009). In prin- as pigments responsible for these colours ciple, flowers of this rare phenotype ex- (AYRANCI & ERKAN, 2013). Exceptional- pose a higher receptive surface to pollen ly, two individuals bearing yellowish- grains dispersed by wind than its counter- white fruits were found in a large popula- parts (NIKLAS, 1987; PAW U & HOTTON, tion of Phillyrea angustifolia (n=217) lo- 1989). Moreover, because of the elongated cated at a cleared zone (≈4 ha) within a growth of the stigma, this abnormal in- forest of Pinus pinea L. (cf. AVILÉS & al., crease in receptive area is not accompa- 2015 for a comprehensive description of the nied by a proportional increment in its di- territory). ameter, which reduces boundary layer re- The study population presents a mar- sistance for pollen deposition (WHITE- ked biannual pattern of fruiting (cf. HE- HEAD, 1983). RRERA & al., 1998: 588), where years with Additionally, a deeper stigma could dominance of vegetative growth alternate favour the selection of larger pollen grains, with years of massive crop of flowers and which are potentially more competitive fruits. In the latter, apparent differences in due to increased pollen-tube