Multilocus Data Analysis Reveal the Diversity of Cryptic Species in the Tillandsia ionantha (Bromeliaceae: Tillansiodeae) Complex.

Independent evolutionary lineages or species that lack phenotypic variation as an operative criterion for their delimitation are known as cryptic species. However, these have been delimited using other data sources and analysis. The aims of this study are: (1) to evaluate the divergence of the populations of the T. ionantha complex; and (2) to delimit the species using multilocus data, phylogenetic analysis and the coalescent model. Phylogenetic analyses, genetic diversity and population structure, and isolation by distance analysis were performed. A multispecies coalescent analysis to delimit the species was conducted. Phylogenetic analysis showed that T. ionantha is polyphyletic composed of eight evolutionary lineages. Haplotype distribution and genetic differentiation analysis detected strong population structure and high values of genetic differentiation among populations. The positive correlation between genetic differences with geographic distance indicate that the populations are evolving under the model of isolation by distance. The coalescent multispecies analysis performed with starBEAST supports the recognition of eight lineages as different species. Only three out of the eight species have morphological characters good enough to recognize them as different species, while five of them are cryptic species. Tillandsia scaposa and T. vanhyningii are corroborated as independent lineages, and T. ionantha var. stricta changed status to the species level.

The role of alien species on plant-floral visitor network structure in invaded communities.

The interactions between pairs of native and alien plants via shared use of pollinators have been widely studied. Community level studies however, are necessary in order to fully understand the factors and mechanisms that facilitate successful plant invasion, but these are still scarce. Specifically, few community level studies have considered how differences in invasion level (alien flower abundance), and degree of floral trait similarity between native and invasive species, mediate effects on native plant-pollinator communities. Here, we evaluated the role of alien species on overall plant-floral visitor network structure, and on species-level network parameters, across nine invaded coastal communities distributed along 205 km in Yucatán, México that vary in alien species richness and flower abundance. We further assessed the potential the role of alien plant species on plant-floral visitor network structure and robustness via computational simulation of native and invasive plant extinction scenarios. We did not find significant differences between native and alien species in their functional floral phenotypes or in their visitation rate and pollinator community composition in these invaded sites. Variation in the proportion of alien plant species and flower abundance across sites did not influence plant-pollinator network structure. Species-level network parameters (i.e., normalized degree and nestedness contribution) did not differ between native and alien species. Furthermore, our simulation analyses revealed that alien species are functionally equivalent to native species and contribute equally to network structure and robustness. Overall, our results suggest that high levels of floral trait similarity and pollinator use overlap may help facilitate the integration of alien species into native plant-pollinator networks. As a result, alien species may also play a similar role than that of natives in the structure and stability of native plant and pollinator communities in the studied coastal sand dune ecosystem.

Floristic affinities of the lowland savannahs of Belize and southern Mexico.

Environmental heterogeneity of Belize and southern Mexico savannahs as well as their geographical location suggest that these plant communities share floristic elements, making them conducive to a phytogeographical analysis. The aim of this study was to analyse the floristic affinities of nine savannahs of Belize and southern Mexico and to explain the similarities and differences amongst them. A binary data matrix containing 915 species was built based on the authors' own collections and on nine floristic lists already published. A second data matrix, consisting of 113 species representing trees, was also used since most literature on neotropical savannahs has focused on this life form. In addition, the ten most species-rich families as well as the characteristic species present in more than five savannahs were analysed. Floristic similarities were calculated using the Jaccard index. Dendrograms obtained in both types of analysis showed clusters with low similarity values, corresponding to geographic locations formed by the savannahs of Belize-Tabasco and the Yucatan Peninsula. The floristic affinities of the savannahs may be explained in terms of heterogeneity in climate and physiography. The Yucatan Peninsula and Belize-Tabasco groups have differences in climate type and the amount of rainfall. In addition, the Yucatan Peninsula savannahs are established at the bottom of karstic valleys, while the Belize and Tabasco savannahs develop on extensive flatlands. The savannahs of Oaxaca have the same climate type and amount of rainfall as those of the Yucatan Peninsula but they are distributed along peaks and the slopes of shale hills. Fabaceae and Poaceae mainly dominated the local floras with 121 and 116 species each; remarkably, Melastomataceae was absent in the Yucatan Peninsula and Oaxaca. Nine species occurred in five to seven savannahs, confirming that they are widespread in both Belize and southern Mexico, and the Neotropics. Geographic location and floristic affinities of the nine savannahs support, to some extent, three different biogeographic provinces.

ANTIPROTOZOAL ACTIVITY OF EXTRACTS OF ELAEODENDRON TRICHOTOMUM (CELASTRACEAE).

BACKGROUND: Chagas disease, amebiasis, giardiasis and trichomoniasis represent a serious health problem in Latin America. The drugs employed to treat these illnesses produce important side effects and resistant strains have appeared. The present study was aimed to evaluate the antiprotozoal activity of leaves, stem bark and root bark of Elaeodendron trichotomum, a celastraceus, that is used in Mexico as an anti-infective in febrile-type diseases. MATERIALS AND METHODS: Dichloromethane and methanol extracts of leaves, bark and roots of Elaeodendron trichotomum were tested against Entamoeba histolytica, Giardia lamblia, Trichomonas vaginalis, and Trypanosoma cruzi. A quantitative HPLC analysis of pristimerin and tingenone was performed. RESULTS: The dichloromethane extract of roots was active against E. histolytica, G. lamblia, T. vaginalis, and T. cruzi, at IC50's of 0.80, 0.44, 0.46, and 2.68 µg/mL, respectively. The HPLC analysis revealed the presence of tingenone (3.84%) and pristimerin (0.14%). CONCLUSIONS: The dichloromethane extract of the roots bark showed significant activity against all screened protozoa.

Diversidad, estructura y afinidades florísticas de un bosque temporalmente inundable de la Península de Yucatán / Diversity, structure and floristic affinities of a temporarily flooded forest of the Yucatan Peninsula

ResumenLos bosques temporalmente inundables (BTI's) se encuentran entre las comunidades arbóreas más amenazadas del sureste de México y de manera contradictoria entre las menos conocidas en términos de su diversidad. Por lo que el objetivo del presente estudio fue caracterizar la riqueza, diversidad (Shannon-Wiener) y dominancia (valor de importancia relativo; VIR) del componente leñoso de un BTI de la península de Yucatán, así como evaluar sus afinidades florísticas con otros BTI's y bosques de tierras altas (BTA's) del sureste de México. Se utilizó un método de muestreo basado 10 cuadrantes de 10 x 20 m (2 000 m2), donde se registraron todos los individuos leñosos con diámetro ≥ 1cm y altura ≥ 1.5 m. Se usó un análisis de similitud florística que incluyó 192 géneros de plantas leñosas presentes en BTI's y BTA's de la península de Yucatán y BTI's Tabasco. Se realizó una prueba de correlación de Mantel para determinar si la distancia geográfica posee efecto sobre su similitud florística entre BTI's y BTA's de la península de Yucatán. El BTI estudiado se caracterizó por una baja diversidad (2.79) y riqueza de especies (56), así como por una alta dominancia (52.3 % del VIR en cinco especies). Especies dominantes como Haematoxylum campechianum, Dalbergia glabra, Cameraria latifolia, Byrsonima crassifolia, Crescentia cujete y Terminalia buceras denotan una afinidad florística neotropical típica de hábitats inundables. La estructura de la comunidad se caracterizó por presentar un patrón de "J" invertida para la distribución de los individuos en las clases diamétricas y de alturas. La alta densidad de lianas leñosas principalmente de Dalbergia glabra (22 % de los individuos registrados) sugiere un óptimo estado de conservación para el área de estudio. El análisis de relaciones florísticas reveló que en su mayoría BTI's de la península de Yucatán se agrupan con alta similitud (55 %) independientemente de los BTA's adyacentes, sin embargo, guardan mayor similitud con ellos (36 % de similitud) que con BTI´s de otras regiones (16 % de similitud). Según la prueba de Mantel, la similitud entre sitios no se encuentra influenciada por su proximidad geográfica (r= -0.098, p>0.05). Esto enfatiza la necesidad de generar estrategias de conservación para los BTI's de la península de Yucatán de manera independiente de otras regiones del sureste de México. Nuestros resultados sugieren que el BTI de la región estudiada posee una diversidad similar a otros BTI's del sureste de México, una composición florística diferente de BTA's adyacentes y una estructura con óptimo estado de conservación, características que indican su importancia para la conservación de la flora regional. Son necesarios estudios ecológicos adicionales para generar bases sólidas para el manejo y conservación de los BTI´s.

AbstractTemporarily flooded forests (TFF's) are among the most endangered tree communities in Southeast Mexico and in a contradictory way among the least known in terms of their diversity. Therefore, the aim of this study was to characterize the richness, diversity (Shannon-Wiener) and dominance (relative importance value; RIV) of a TFF of the Yucatan Peninsula, and evaluate its floristic affinities with other TFF's and upland forests (UF's) of Southeast Mexico. A sampling method based on 10 quadrants of 10 x 20 m (2 000 m2) was used to record all woody individuals with diameter ≥ 1 cm and height ≥ 1.5 m. A floristic similarity analysis was used including 192 genera of woody plants belonging to TFF's and UF's of the Yucatan and Tabasco TFF's. A Mantel correlation test was performed to determine if the geographic distance has effect on the floristic similarities between TFF's and UF´s of the Yucatan peninsula. The TFF under study was characterized with a low level of diversity (2.79) and species richness (56), and a high dominance level (52.3 % of RIV in five species). Dominant species such as Haematoxylum campechianum, Dalbergia glabra, Cameraria latifolia, Byrsonima crassifolia, Crescentia cujete and Terminalia buceras showed a floristic neotropical affinity typical of floodable habitats. The structure of the community was characterized by an inverted "J" pattern for the distribution of individuals in the diametric and height classes. The high density of woody lianas, mainly of Dalbergia glabra (22 % of the recorded individuals) suggested an optimal state of conservation of the studied area. The floristic similarity analysis revealed that most of TFF's in Yucatan Peninsula were grouped with high similarity (55 %) independently of the adjacent UF's; however, TFF´s resulted similar among them (36 % similarity) when compared with TFF's from other regions (16 % similarity). According to the Mantel test, the similarity between sites is not influenced by its geographical proximity (r = -0.098, p>0.05). This emphasizes the need to generate conservation strategies for the TFF's of the Yucatan peninsula independently from other regions of Southeast Mexico. Our results suggest that the TFF of the studied region has a similar diversity from other TFF's in Southeast Mexico, a different floristic composition compared with adjacent UF's and a structure with an optimal conservation status, characteristics that indicate their importance for the regional flora conservation. Further ecological studies are needed to build a solid foundation for management and conservation for the TFF's. Rev. Biol. Trop. 65 (3): 868-880. Epub 2017 September 01.