Mantenimiento simultáneo del dimorfismo sexual y la condición hermafrodita en plantas. Un caso típico de selección negativa dependiente de la frecuencia

Las plantas con flor presentan sistemas de reproducción muy variados, con adaptaciones aparentes para su funcionamiento. No sorprende que hayan atraído el interés de los evolucionistas desde antiguo generando literatura de gran impacto, por ejemplo, en lo referente a la evitación de la endogamia. Sin embargo, en comparación con el equivalente animal, algunos aspectos sólo se han desarrollado parcial y recientemente, como la selección sexual, los conflictos de intereses reproductores, o la optimización del apareamiento. Hay un tipo de sistema de reproducción, el polimorfismo estilar, que ofrece buenas oportunidades para explorar hasta qué punto las plantas pueden controlar la pareja con la que se cruzan, o simplemente no necesitan pareja. Revisamos la evidencia disponible en un grupo de plantas (Narcissus) que muestran una amplia variedad de comportamientos. Algunas de las especies de este grupo de plantas han mostrado ser muy adecuadas para estudios de selección dependiente de la frecuencia, dada la presencia de morfos florales cuyo fitness depende de la frecuencia de cada morfo.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Darwin también era botánico

Reivindicación de la figura de Darwin como botánico, muchas veces ignorada por el público en general, además el autor llama la atención sobre la gran deuda que tienen todos los botánicos con e

Avoiding sexual interference: herkogamy and dichogamy in style dimorphic flowers of Narcissus broussonetii (Amaryllidaceae)

Spatial (herkogamy) or temporal (dichogamy) separation of sex organs are mechanisms considered to restrict self-pollination and promote outcrossing. Additionally, avoidance of self-interference is proposed to be the driving force for the evolution of these mechanisms, particularly in self-incompatible species. However, species with anthers and stigmas at different levels may increase the rate of imprecise pollen transfer, resulting in pollen discounting. Non-reciprocal stylar dimorphism has been considered a transitional, unstable stage towards the evolution of reciprocal style dimorphism (distyly), to simultaneously avoid interference and lack of precision. In this study we investigate the spatial and temporal separation of sex organs in a population of the style dimorphic and self-incompatible Narcissus broussonetii and their consequences in the reciprocity between the sex organs of morphs and their fecundity. First, we evaluated the relative growth of sex organs after anthesis. Then, we studied the stigma receptivity along the flower lifespan including its effect on seed production in both morphs. Finally, given the weak reciprocity between the sex organs of morphs of this species, we estimated population genetic diversity parameters in Long- and Short-styled plants to explore differences between them as a result of rates of inbreeding due to different mating strategies. We observed that Long-styled plants and Short-styled plants present different strategies to avoid sexual interference and both of them had negative consequences in the reciprocity between the sex organs of morphs. Long-styled plants exhibited a delay in stigma receptivity and a higher growth rate of the style after anthesis, while Short-styled plants presented higher herkogamy and no delay in stigma receptivity. These findings suggest that the avoidance of self-interference, in stylar dimorphic Narcissus species, seems to be more critical than improving of reciprocity between the sex organs of morphs. This might explain why reciprocal herkogamy (distyly) is rare in the genus.España, Ministerio de Economía y Competitividad (CGL2009-12565 and CGL2013-45037 PGC2018-099608-B-I00)ESpaña, Plan Andaluz de Investigación (RNM-210)España, Ministerio de Economía y Competitividad (BES-2014-067795 and EEBB-I-16-10587

Morph ratio variation and sex organ reciprocity in style-dimorphic Narcissus assoanus

The maintenance of floral polymorphisms depends on rates and efficiency of cross-pollination within and among mating types in relation to their relative frequency. Here, we examine whether stigma-anther reciprocity in style-dimorphic Narcissus assoanus (populations show either 1: 1 ratios of long-styled [L-morph] and short-styled [S-morph] plants or significantly L-morph-biased ratios) is correlated with morph ratio variation and whether such differences affect female fitness. In a natural population we created experimental plots of S-morph maternal plants and quantified their female fertility in the presence of either L-morph donors or S-morph donors with only their lower anther levels (we emasculated upper-level anthers).We also quantified floral traits and reciprocity in the positions of stigmas and anthers in 30 natural populations across the species' geographic distribution. We found an increase in seed set on maternal S-morph plants in the presence of L-morph donors and patterns of trait variation that may contribute to enhanced reciprocity with increasing frequency of the S-morph. Subtle differences in the position of sex organs affect pollen transfer and are correlated with morph ratio variation, indicative of frequency-dependent selection.Ministerio de Ciencia y Tecnología CGL2006-13847-CO2 CGL2009-1256

What is a tree in the mediterranean basin hotspot? A critical analysis

Background: Tree species represent 20% of the vascular plant species worldwide and they play a crucial role in the global functioning of the biosphere. The Mediterranean Basin is one of the 36 world biodiversity hotspots, and it is estimated that forests covered 82% of the landscape before the first human impacts, thousands of years ago. However, the spatial distribution of the Mediterranean biodiversity is still imperfectly known, and a focus on tree species constitutes a key issue for understanding forest functioning and develop conservation strategies. Methods: We provide the first comprehensive checklist of all native tree taxa (species and subspecies) present in the Mediterranean-European region (from Portugal to Cyprus). We identified some cases of woody species difficult to categorize as trees that we further called “cryptic trees”. We collected the occurrences of tree taxa by “administrative regions”, i.e. country or large island, and by biogeographical provinces. We studied the species-area relationship, and evaluated the conservation issues for threatened taxa following IUCN criteria. Results: We identified 245 tree taxa that included 210 species and 35 subspecies, belonging to 33 families and 64 genera. It included 46 endemic tree taxa (30 species and 16 subspecies), mainly distributed within a single biogeographical unit. The countries with the highest tree richness are Greece (146 taxa), Italy (133), Albania (122), Spain (155), Macedonia (116), and Croatia (110). The species-area relationship clearly discriminated the richest central-eastern (Balkans) and northern (Alpine and Cevenno-Pyrenean) biogeographical provinces, against the five western provinces in the Iberian Peninsula. We identified 44 unrecognized “cryptic trees”, representing 21% of the total trees. Among the 245 taxa identified, 19 are considered to be threatened (15 CR + EN + VU) or near threatened (4 NT) by IUCN. Conclusions: The Mediterranean-European region includes an unsuspectedly high number of tree taxa, almost 200 tree taxa more than in the central European region. This tree diversity is not distributed evenly and culminates in the central-eastern part of the Mediterranean region, whereas some large Tyrrhenian islands shelter several narrow endemic tree taxa. Few taxa are recognized as threatened in the IUCN Red list, and the vulnerability of these species is probably underestimated.French Foundation for Research on Biodiversity (FRB). Centre for Synthesis and Analysis of Biodiversity data ANR-11-LABX-006

A phylogenetic hypothesis for Helianthemum (Cistaceae) in the Iberian Peninsula

We have sequenced the nuclear DNA internal transcribed spacer (ITS1+5.8S+ITS2) from samples collected in the field belonging to all taxa of Helianthemum in the Iberian Peninsula and analysed the data matrix by both Bayesian and Maximum Likelihood approaches. The phylogenetic hypothesis that we present here provides strong support for the monophyly of the genus and for the above-species systematics (sections and subgenera) considered in Flora iberica. Nevertheless, most species and subspecies in sections Helianthemum and Pseudocistus clustered in ample polytomies with poor resolution and branch support. This topology is interpreted to be consequence of frequent events of hybridization and introgression and/or rapid adaptive radiation in the genus Helianthemum, the most diversified lineage within the family Cistaceae.En este trabajo presentamos una hipótesis filogenética para el género Helianthemum en la Península Ibérica. Para ello hemos recolectado en el campo material de todos los taxones y analizado las secuencias del marcador nuclear ITS (internal transcribed spacer) completo (ITS1+5.8S+ITS2) tanto con métodos Bayesianos como de Máxima Verosimilitud. Nuestra hipótesis muestra gran apoyo para la monofilia de género y para los taxones supra-específicos considerados en Flora iberica (secciones y subgéneros). En cambio, las especies y subespecies de las secciones más extensas (Helianthemum y Pseudocistus) se han agrupado en amplias politomías con muy bajo apoyo. Interpretamos que esta marcador nuclear tiene baja resolución debido a eventos frecuentes de hibridación e introgresión así como de radiación adaptativa en el género Helianthemum, que es el linaje más diversificado de toda la familia Cistaceae

Polinización y arquitectura floral en ericaceae de Andalucía occidental

Se estudian características florales y, en general, reproductivas, en diez especies de Ericaceae de Andalucía Occidental (Suroeste de España). Se examinan las posibles correlaciones entre morfología floral y sistema de polinización, así como su fenología de floración e intensidad de fructificación.Reproductive attributes of ten species in the genera Erica, Calluna, and Arbutus (Ericaceae) living in W Andalucía (southwest Spain) are reported. The relationship between flower morphology and pollination system, together with the flowering phenology of the species and fruiting capacity in absence of pollination vectors are also studied