The diversity and evolution of pollination systems in large plant clades: Apocynaceae as a case study.

Background and Aims: Large clades of angiosperms are often characterized by diverse interactions with pollinators, but how these pollination systems are structured phylogenetically and biogeographically is still uncertain for most families. Apocynaceae is a clade of >5300 species with a worldwide distribution. A database representing >10 % of species in the family was used to explore the diversity of pollinators and evolutionary shifts in pollination systems across major clades and regions. Methods: The database was compiled from published and unpublished reports. Plants were categorized into broad pollination systems and then subdivided to include bimodal systems. These were mapped against the five major divisions of the family, and against the smaller clades. Finally, pollination systems were mapped onto a phylogenetic reconstruction that included those species for which sequence data are available, and transition rates between pollination systems were calculated. Key Results: Most Apocynaceae are insect pollinated with few records of bird pollination. Almost three-quarters of species are pollinated by a single higher taxon (e.g. flies or moths); 7 % have bimodal pollination systems, whilst the remaining approx. 20 % are insect generalists. The less phenotypically specialized flowers of the Rauvolfioids are pollinated by a more restricted set of pollinators than are more complex flowers within the Apocynoids + Periplocoideae + Secamonoideae + Asclepiadoideae (APSA) clade. Certain combinations of bimodal pollination systems are more common than others. Some pollination systems are missing from particular regions, whilst others are over-represented. Conclusions: Within Apocynaceae, interactions with pollinators are highly structured both phylogenetically and biogeographically. Variation in transition rates between pollination systems suggest constraints on their evolution, whereas regional differences point to environmental effects such as filtering of certain pollinators from habitats. This is the most extensive analysis of its type so far attempted and gives important insights into the diversity and evolution of pollination systems in large clades.

Population genetic analysis and bioclimatic modeling in Agave striata in the Chihuahuan Desert indicate higher genetic variation and lower differentiation in drier and more variable environments.

PREMISE OF THE STUDY: Is there an association between bioclimatic variables and genetic variation within species? This question can be approached by a detailed analysis of population genetics parameters along environmental gradients in recently originated species (so genetic drift does not further obscure the patterns). The genus Agave, with more than 200 recent species encompassing a diversity of morphologies and distributional patterns, is an adequate system for such analyses. We studied Agave striata, a widely distributed species from the Chihuahuan Desert, with a distinctive iteroparous reproductive ecology and two recognized subspecies with clear morphological differences. We used population genetic analyses along with bioclimatic studies to understand the effect of environment on the genetic variation and differentiation of this species. METHODS: We analyzed six populations of the subspecies A. striata subsp. striata, with a southern distribution, and six populations of A. striata subsp. falcata, with a northern distribution, using 48 ISSR loci and a total of 541 individuals (averaging 45 individuals per population). We assessed correlations between population genetics parameters (the levels of genetic variation and differentiation) and the bioclimatic variables of each population. We modeled each subspecies distribution and used linear correlations and multifactorial analysis of variance. KEY RESULTS: Genetic variation (measured as expected heterozygosity) increased at higher latitudes. Higher levels of genetic variation in populations were associated with a higher variation in environmental temperature and lower precipitation. Stronger population differentiation was associated with wetter and more variable precipitation in the southern distribution of the species. The two subspecies have genetic differences, which coincide with their climatic differences and potential distributions. CONCLUSIONS: Differences in genetic variation among populations and the genetic differentiation between A. striata subsp. striata and A. striata subsp. falcata is correlated with differences in environmental climatic variables along their distribution. We found two distinct gene pools that suggest active differentiation and perhaps incipient speciation. The detected association between genetic variation and environment variables indicates that climatic variables are playing an important role in the differentiation of A. striata.

[Spatial distribution and ecological structure of Thalassia testudinum (Hydrocharitaceae) in two reefs of Veracruz Reef System National Park, Mexico]. / Distribución espacial y estructura morfométrica de las praderas de Thalassia testudinum (Hydrocharitaceae) en dos arrecifes del Parque Nacional Sistema Arrecifal Veracruzano, México.

Seagrasses in coastal environments have been threatened by increased human activities; these have negatively altered processes and environmental services, and have decreased grassland areas. The aim of this study was to generate knowledge of Thalassia testudinum distribution, state of the structure and fragmentation level in two reefs of the Veracruz Reef System National Park (PNSAV). Two different reefs were selected: Sacrificios in the North and near the coast, and Cabezo in the South and away from the coast. Shoot-specific and area-specific characteristics of submerged macrophytes meadows present were determined, and four morpho-functional groups were identified. Significant differences between plant coverage were tested through nonparametric ANOVA, Kruskal-Wallis test. A supervised classification of spatial high-resolution image verified with field data was performed (55 Sacrificios and 290 Cabezo). The fragmentation level was calculated using landscape metrics, class level and thematic maps were made based on four covers. The meadows were dominated by Thalassia testudinum; maximum densities were 208 shoot/m2 in Cabezo, and 176 shoot/m2 in Sacrificios. Cabezo presented grasses with short (9 cm) and thin leaves (0.55 cm) on average; while Sacrificios showed longer (23.5 cm) and thicker (1 cm) leaves. Sacrificios showed lower fragmentation degree than Cabezo; in both cases, the vegetation cover fragmentation corresponded to less than 50 %. Although Cabezo reef presents further fragmentation, which creates a large number of microenvironments, being recognized for its importance as recruitment area. This work serves as a baseline for the creation of an adequate management plan (formation of a core area of Cabezo). It is necessary to complement this work with new efforts for the recognition of seagrass prairies in all PNSAV reefs, as well as periodic monitoring and recognition of ecosystem services. .

Universal hydraulics of the flowering plants: vessel diameter scales with stem length across angiosperm lineages, habits and climates.

Angiosperm hydraulic performance is crucially affected by the diameters of vessels, the water conducting conduits in the wood. Hydraulic optimality models suggest that vessels should widen predictably from stem tip to base, buffering hydrodynamic resistance accruing as stems, and therefore conductive path, increase in length. Data from 257 species (609 samples) show that vessels widen as predicted with distance from the stem apex across angiosperm orders, habits and habitats. Standardising for stem length, vessels are only slightly wider in warm/moist climates and in lianas, showing that, rather than climate or habit, plant size is by far the main driver of global variation in mean vessel diameter. Terminal twig vessels become wider as plant height increases, while vessel density decreases slightly less than expected tip to base. These patterns lead to testable predictions regarding evolutionary strategies allowing plants to minimise carbon costs per unit leaf area even as height increases.

To converge or not to converge in environmental space: testing for similar environments between analogous succulent plants of North America and Africa.

BACKGROUND AND AIMS: Convergent evolution is invoked to explain similarity between unrelated organisms in similar environments, but most evaluations of convergence analyse similarity of organismal attributes rather than of the environment. This study focuses on the globular succulent plants of the Americas, the cacti, and their counterparts in Africa in the ice-plant, spurge and milkweed families. Though often held up as paragons of convergent morphological evolution, the environmental similarity of these plants has remained largely unexamined from a quantitative perspective. METHODS: Five hotspots (centres of high species diversity of globular succulents) were selected, two in Mexico and three in South Africa. Their environments were compared using niche modelling tools, randomization tests of niche similarity and multivariate analyses to test for environmental similarity. KEY RESULTS: Although the sites selected have 'similar' but unrelated life forms, almost all our results highlighted more climate differences than similarities between the hotspots. Interprediction of niches within and between continents, a niche equivalence test, and MANOVA results showed significant differences. In contrast, a niche similarity test showed that the comparisons of Cuatrociénegas-Richtersveld, Huizache-Knersvlakte and Huizache-Richtersveld were similar. CONCLUSIONS: Differences in rainfall and temperature regimes and the potential effect of edaphic factors may be involved in the differences between the hotspots. In addition, differences in structure, morphology and physiology of the globular succulents may coincide with some of the climatic dissimilarities; i.e. given convergence as the evolution of similar morphologies under similar conditions, then it may be that differing environments diagnose inconspicuous morphological differences. Moreover, although fine-scale differences between sites were found, a coarser perspective shows that these sites are clearly similar as drylands with relatively moderate drought and mild temperatures, illustrating how all studies of convergence must address the issue of how similar two entities must be before they are considered convergent.

Revision of the genus Agrostis (Poaceae, Pooideae, Poeae) in Megamexico.

Agrostis is one of the most diverse genera of the Poaceae, including ca. 198 species, principally distributed in cold and temperate regions of the world, but also found in the high mountains of the tropics. We present a revision based on morphoanatomical evidence, for the biogeographic region known as Megamexico 3 (i.e., Mexico including the desert areas of southern USA and the Central America territory, to northern Nicaragua). We include taxonomic descriptions and an identification key for the found taxa, maps with the known geographical distribution of the species, and figures with the morphoanatomical characteristics, elevation and phenology. Agrostis is represented in the study zone by 20 species, of which four are endemic and three are introduced. Most records of the genus are distributed in the mountains, above 1500 m a.s.l., in open areas of temperate forests, with conifers and Quercus. Specimens with spikelets occur year round, but most records occur during the wet season, in the months of July to October. We propose a preliminary conservation assessment for each species in the study zone, according to the International Union for Conservation of Nature categories: one with Deficient Data (DD), six as Endangered (EN), two as Vulnerable (VU), and 11 as Least Concern (LC).

ResumenAgrostis es uno de los géneros más diversos de las Poaceae, con ca. 198 especies, principalmente distribuidas en regiones frías y templadas del mundo, aunque también se pueden encontrar en grandes elevaciones de los trópicos. En este trabajo se presenta una revisión basada en evidencia morfoanatómica para la región biogeográfica conocida como Megaméxico 3 (i.e., México incluyendo las áreas desérticas del sur de los EUA y el territorio de Centroamérica hasta el norte de Nicaragua). Se incluyen descripciones taxonómicas y una clave de identificación para los taxones encontrados, mapas con la distribución geográfica conocida de las especies, así como figuras con las características morfoanatómicas, elevación y fenología. Agrostis está representado en la zona de estudio por 20 especies, cuatro de las cuales son endémicas y tres son introducidas. La mayoría de los registros del género se distribuyen en regiones montañosas, por arriba de los 1500 de elevación, en áreas abiertas de bosques templados, con coníferas y Quercus. Es posible encontrar ejemplares con espiguillas durante todo el año, pero la mayoría de los registros ocurren durante la época lluviosa, durante los meses de julio a octubre. Se propone una evaluación preliminar de conservación para cada especie en la zona de estudio, de acuerdo con las categorías de la Union Internacional para la Conservación de la Naturaleza: una con Datos Deficientes (DD), seis como Amenzadas (EN), dos como Vulnerables (VU) y 11 de Preocupación Menor (LC).

Essential (Cu, Zn) and nonessential (Pb, Cd) metals in the muscle of leopard groupers (Mycteroperca rosacea) from a mining port in the Gulf of California, Mexico: human health risk assessment.

Mining activities are a current environmental issue due to heavy metal release and subsequent metal uptake by organisms. In this study, we quantified the concentrations of essential (Cu, Zn) and toxic (Cd, Pb) elements in the muscle of 248 leopard groupers, Mycteroperca rosacea, captured by spearfishing and free diving close to a mining district in the Gulf of California during 2014-2015. We analysed metals using high-resolution inductively coupled plasma source mass spectrometry (HR-ICP-MS). We analysed metal concentrations by fish size, sex, maturity, season, year and risk factor for human consumption. The results indicated common levels of essential elements (Cu: 11 ± 34.3 µg/g, Zn: 377 ± 1390 µg/g) in comparison with toxic elements (Cd: 0.06 ± 0.1 µg/g, Pb: 0.98 ± 1.5 µg/g). Cadmium was within the permissible limit of Mexican standards (0.5 µg/g), but lead content bordered its limit (1.0 µg/g). Heavy metal concentrations were comparable between males and females. Metal variations were not significantly correlated with sex, maturity, season or year (p > 0.05). The evaluation of benefits (daily mineral intake) and risks (target hazard quotients) to health indicated that these fish did not represent a risk of adverse effects to consumers within worldwide limits, while the nutritional benefits were high.

Betalain, Acid ascorbic, phenolic contents and antioxidant properties of purple, red, yellow and white cactus pears.

Commercialization of cactus pears based on their antioxidant properties can generate competitive advantages, and these can turn into business opportunities and the development of new products and a high-value ingredient for the food industry. This work evaluated the antioxidant activities (1,1-diphenyl-2-picrylhydrazyl radical-scavenging, protection against oxidation of a ß-carotene-linoleic acid emulsion, and iron (II) chelation), the content of total phenolic compounds, ascorbic acid, betacyanin, betaxanthin and the stability of betacyanin pigments in presence of Cu (II)-dependent hydroxyl radicals (OH•), in 18 cultivars of purple, red, yellow and white cactus pear from six Mexican states. Our results indicated that the antiradical activities from yellow and white cactus pear cultivars were not significantly different (p < 0.05) and were lower than the average antiradical activities in red and purple cultivars. The red cactus pear from the state of Zacatecas showed the highest antioxidant activity. The free radical scavenging activity for red cactus pears was significantly correlated (p < 0.05) to the concentration of total phenolic compounds (R(2) = 0.90) and ascorbic acid (R(2) = 0.86). All 18 cultivars of cactus pears studied showed significant chelating activity of ferrous ions. The red and purple cactus pears showed a great stability when exposed to OH•.

Partial characterization of digestive proteases in juveniles of Microphis brachyurus (short-tailed pipefish) (Syngnathiformes: Syngnathidae)

Short-tailed pipe fish (Microphis brachyurus) is a freshwater organism with high economic potential for the aquarium hobby, so it is necessary to implement methods to promote its culture through studies of digestive physiology. General activities of acid and alkaline proteases were evaluated, as well as the effect of pH, temperature and inhibitors. The optimal pH of stomach proteases was 2, while the optimal pH of intestinal proteases was 10. Optimal temperature for the acidic proteases was 35 ºC, while for alkaline proteases it was 45 ºC. Thermal stability showed high resistance at 35 ºC for both acid and alkaline proteases (above 100% residual activity). Acid proteases are resistant at pH 2 (50% of residual activity), meanwhile alkaline proteases were highly resistant at pH 10 (90% of residual activity). Acid proteases were inhibited by 80% with pepstatin A and alkaline proteases were inhibited with TLCK and TPCK for trypsin (75%) and chymotrypsin (80%), respectively. Finally, metallo-proteases were 75% partially inhibited some serine proteases by 75% with EDTA. In conclusion, M. brachyurus has a good digestive capacity, since they can degrade a wide variety of proteins due to their greater proteolytic activity.(AU)

El pez pipa (Microphis brachyurus) es un organismo dulceacuícola con alto potencial económico para la acuarofilia; sin embargo, es necesario implementar su cultivo a través de estudios de fisiología digestiva. Se evaluó el efecto del pH, temperatura e inhibidores sobre las actividades enzimáticas de proteasas ácidas y alcalinas. El pH óptimo de proteasas estomacales es de 2, mientras que el de proteases intestinales es de 10. La temperatura óptima de proteasas ácidas es de 35 ºC y las alcalinas de 45 ºC. La estabilidad térmica para proteasas ácidas y alcalinas es a los 35 ºC (más de 100% de actividad residual). La estabilidad a los diferentes pH de las proteasas ácidas es en 2 (50 % de la actividad residual), mientras que para las proteasas alcalinas es en 10 (90 % de la actividad residual). Las proteasas ácidas fueron inhibidas en 80% con pepstatina A y las proteasas alcalinas fueron altamente inhibidas con TLCK para tripsina (75%) y TPCK quimitripsina (80%). Finalmente, las metaloproteasas fueron inactivadas con EDTA en 70%. En conclusión, M. brachyurus tiene una buena capacidad digestiva al degradar una amplia variedad de proteinas debido a su alta actividad proteolítica.(AU)

Distribución espacial y estructura morfométrica de las praderas de Thalassia testudinum (Hydrocharitaceae) en dos arrecifes del Parque Nacional Sistema Arrecifal Veracruzano, México / Spatial distribution and ecological structure of Thalassia testudinum (Hydrocharitaceae) in two reefs of Veracruz Reef System National Park, Mexico

ResumenLos pastos marinos son ambientes costeros que se han visto amenazados por el incremento de las actividades humanas. Alterando de forma negativa los procesos y servicios ambientales que presentan, así como la disminución de praderas. El objetivo es generar conocimiento de la distribución, estado de la estructura y nivel de fragmentación en dos arrecifes del Parque Nacional Sistema Arrecifal Veracruzano (PNSAV). Se eligieron dos praderas en arrecifes con características distintas: Sacrificios en el Norte que se encuentra cerca de la costa y Cabezo en el Sur que está alejado de la costa. Se determinaron las características específicas de haz y área de las praderas de macrófitas sumergidas presentes e identificaron cuatro grupos de cobertura morfofuncionales. Se comprobaron diferencias significativas entre coberturas (ANOVA no paramétrico, prueba de Kruskal-Wallis). Se realizó una clasificación supervisada de una imagen espacial de alta resolución verificada con datos de campo (55 Sacrificios y 290 Cabezo). El nivel de fragmentación se calculó usando métricas de paisaje a nivel de clase y se realizaron mapas temáticos en función de las cuatro coberturas. Las praderas se encuentran dominadas por Thalassia testudinum; se tuvieron densidades máximas de 208 haces/m2 para Cabezo y 176 haces/m2 en Sacrificios. Cabezo presentó pastos de hojas cortas (9 cm) y delgadas (0.55 cm) en promedio; Sacrificios tuvo hojas más largas (23.5 cm) y gruesas (1 cm). Sacrificios mostró menor grado de fragmentación que Cabezo; en ambos casos la fragmentación de la cobertura vegetal corresponde a menos del 50 %. Aunque el arrecife Cabezo presenta una mayor fragmentación, que crea un gran número de microambientes, siendo reconocido por su importancia como zona de reclutamiento. Este trabajo sirve como una línea de base para la creación de un plan de manejo adecuado (formación de una zona núcleo de Cabezo). Es necesario complementar este trabajo con nuevos esfuerzos del reconocimiento de las praderas de pastos marinos en todos los arrecifes del PNSAV, así como de monitoreos periódicos y reconocimiento de sus servicios ecosistémicos.

AbstractSeagrasses in coastal environments have been threatened by increased human activities; these have negatively altered processes and environmental services, and have decreased grassland areas. The aim of this study was to generate knowledge of Thalassia testudinum distribution, state of the structure and fragmentation level in two reefs of the Veracruz Reef System National Park (PNSAV). Two different reefs were selected: Sacrificios in the North and near the coast, and Cabezo in the South and away from the coast. Shoot-specific and area-specific characteristics of submerged macrophytes meadows present were determined, and four morpho-functional groups were identified. Significant differences between plant coverage were tested through nonparametric ANOVA, Kruskal-Wallis test. A supervised classification of spatial high-resolution image verified with field data was performed (55 Sacrificios and 290 Cabezo). The fragmentation level was calculated using landscape metrics, class level and thematic maps were made based on four covers. The meadows were dominated by Thalassia testudinum; maximum densities were 208 shoot/m2 in Cabezo, and 176 shoot/m2 in Sacrificios. Cabezo presented grasses with short (9 cm) and thin leaves (0.55 cm) on average; while Sacrificios showed longer (23.5 cm) and thicker (1 cm) leaves. Sacrificios showed lower fragmentation degree than Cabezo; in both cases, the vegetation cover fragmentation corresponded to less than 50 %. Although Cabezo reef presents further fragmentation, which creates a large number of microenvironments, being recognized for its importance as recruitment area. This work serves as a baseline for the creation of an adequate management plan (formation of a core area of Cabezo). It is necessary to complement this work with new efforts for the recognition of seagrass prairies in all PNSAV reefs, as well as periodic monitoring and recognition of ecosystem services. Rev. Biol. Trop. 64 (2): 427-448. Epub 2016 June 01.