Visual information transmitted by body position modulates the interaction and behavior of con- and hetero-specific bees during floral visits of the prickly pear Opuntia huajuapensis. Dummy model bees ...in the feeding or horizontal positions on flowers do not hinder Apis mellifera visitation. This exotic species reacted faster to the dummy models of native and conspecifics when in alert or horizontal positions. In contrast, native male Lithurgus littoralis spent more time displaying aggressive behaviors towards the dummy model in the alert or horizontal positions but showed a positive response of native female bees towards the dummy of the exotic A. mellifera when found in the feeding position. Experimental body position during floral visitation provides a visual cue that modifies bee behavior, which in turn determines access to floral resources. The behavior of bees is modulated by the presence of other bees and potentially by the visual information transmitted by the different body positions of bees while visiting flowers. We tested whether bee body position promoted the attraction and/or antagonistic behavior of con- and hetero-specific bees that interacted on prickly pear flowers of Opuntia huajuapensis. To test this, we placed dummy model bees of Apis mellifera and the native Lithurgus littoralis in flowers in three common body positions: alert, feeding, and horizontal. The results showed that dummy model bees in feeding and horizontal body positions attracted A. mellifera bees, while the alert position attracted native male L. littoralis. Male L. littoralis bees spent more time attacking model bees in horizontal and alert positions. The position of dummy bees also influenced response times. Bees of A. mellifera responded fastest to L. littoralis in the alert and horizontal position, male L. littoralis responded fastest to con-specific bees in the alert and feeding position, and female L. littoralis responded fastest to A. mellifera bees in the feeding position. A. mellifera reacted fastest to their con-specific bees in the alert and horizontal body positions. Our results demonstrate, for the first time in bees, that the position of individuals on a floral resource provides important visual information that modulates bee behavior, and illuminates aspects that likely have implications for bees in access to floral resources.
Background and Aims: The family Cactaceae possesses the largest number of species listed as endangered, but biological information as well as ecological studies are needed to assess the conser-vation ...status of cacti and apply guidelines to include or exclude species from red lists. Astrophytum ornatum has a status of vulnerable, but its ecological situation has not been evaluated, so its local and regional status is unknown. The aim of this study was to determine factors influencing the mainte-nance of their populations to provide information to establish their conservation status. Methods: We analyzed the population structure, spatial distribution pattern and reproduction of A. ornatum in one remnant population in Cadereyta de Montes, Querétaro, Mexico.
Key results: The species has an aggregated spatial distribution pattern, which suggests an interac-tion with nurse species or cracks and rocks that provide shade. Individuals are concentrated in the first size categories, 34% were reproductive, large plants have a greater number of reproductive structures but with less seeds per fruit in comparison to medium-sized plants.
Conclusions: The studied population has a potential to grow because its population structure displays the typical form of species with common recruitment. This population structure, high density and the presence of small plants suggest that the remaining population of A. ornatum is in good condition; however, no recruitment of seedlings was observed, there is a high mortality in all size classes and the risks posed to the locality are its proximity to human settlements and sand banks. Global assessment suggests that A. ornatum should be considered a threatened species.
Antecedentes y Objetivos: La familia Cactaceae tiene el mayor número de especies listadas en riesgo de extinción, pero la información biológica y poblacional de estas especies, necesaria para determinar su riesgo poblacional y su estatus de conservación en las listas rojas, es escasa o insuficiente. El estatus de Astrophytum ornatum es vulnerable, pero su situación ecológica no ha sido evaluada, por lo que no se conoce exactamente cuál es su condición local y regional. El objetivo de este estudio fue estimar algunos de los factores que influyen en el mantenimiento de sus poblaciones y aportar información que permita establecer su estatus de conservación.
Métodos: En este trabajo se analizó la estructura poblacional, el patrón de distribución espacial y la reproducción de A. ornatum en una población remanente localizada en Cadereyta de Montes, Querétaro, México.
Resultados clave: Astrophytum ornatum tiene un patrón de distribución espacial agregado, similar a otras especies que requieren nodrizas o grietas y rocas que les proporcionan sombra. La mayoría de sus individuos se concentran en las primeras categorías de tamaño, 34% son reproductivos, las plantas grandes presentan un mayor número de estructuras reproductivas (botones, flores, frutos) y un menor número promedio de semillas por fruto.
Conclusiones: La población estudiada presenta un potencial de crecimiento ya que su estructura poblacional tiene la forma típica de especies con reclutamiento frecuente. Dicha estructura poblacional, la alta densidad y la presencia de plantas pequeñas sugieren que la población está en buenas condiciones; sin embargo, no se observó reclutamiento de plántulas y hay una alta mortalidad en todas las clases de tamaño, además los riesgos para esta población son la cercanía a núcleos de población humana y a bancos de materiales. La evaluación global sugiere que se considere la especie como amenazada.
Invasive alien species frequently possess seed related attributes that contribute to invasion success, such as environmental tolerance, numerous seeds, longevity, rapid germination, and high ...germination rates, among others. These traits can enhance propagule pressure, thus having important implications for management. The genus Kalanchoe contains species widely used in the horticultural trade, but a few have become invasive around the world. We evaluated the performance of Kalanchoe delagoensis seeds of different age to determine the probability of generating a seed bank under dark-light conditions and constant/alternating temperature to assess photoblastic response and seed tolerance to temperature. Seeds were sown following a factorial experiment that comprised four seed ages (5, 8, 11 and 13 months after collection), two temperature conditions (25 °C constant and 16/25 °C alternating), and two light conditions (light and darkness) resulting in 16 experimental treatments with 10 replicates each and 50 seeds per replicate. Seeds were positive photoblastic with no germination under darkness conditions. Final germination percentage ranged from 1.8% to 49.4% among treatments but decreased with seed age and the interaction with temperature. Mean germination time ranged from 4.5 to 10.9 days among treatments. Results suggest that К delagoensis seeds germinate rapidly, and have a neutral response to the 16/25 °C alternating temperature in germinability. Seed viability rapidly decreases within the first year after the reproductive season, suggesting that this species would only form a transient seed bank. Avoiding inflorescence maturation and covering or burying seeds will contribute to the depletion of the seed bank over the short term and could provide adequate control of invasive К delagoensis populations.
García Calva, L.; Golubov, J.; Mandujano, M.C.; Lara-Domínguez, L., and López-Portillo, J., 2019. Assessing Google Earth Pro images for detailed conservation diagnostics of mangrove communities. In: ...Silva, R.; Martínez, M.L.; Chávez, V., and Lithgow, D. (eds.), Integrating Biophysical Components in Coastal Engineering Practices. Journal of Coastal Research, Special Issue No. 92, pp. 33–43. Coconut Creek (Florida), ISSN 0749-0208. Conservation of mangrove ecosystems is one of the major global environmental challenges of this century. To propose viable strategies for its conservation, it is necessary to produce an adequate cartography that enables, among other things, accurate differentiation among plant communities. Google Earth Pro (GEP) images were evaluated as a tool to classify different mangrove communities and were compared to RapidEye satellite (RE) images. The accuracy of the following classifications were compared: (1) one based on the normalized difference vegetation index (NDVI) of a RE image, (2) one based on a mosaic of 141 GEP images, both using object-based image analysis (OBIA) and (3) one based on the visual interpretation (VI) of the same GEP mosaic. It was possible to distinguish ten mangrove communities in 2436 ha, six of them dominated or codominated by the white mangrove Laguncularia racemosa, suggesting that this estuary has a strong riverine influence and low salinities. There was a 97% accuracy on the VI of GEP mosaic, significantly higher than the OBIA classifications done on RE (88%) or GEP (80%) images. These results indicate that GEP, an open access resource, provides similar accuracy when mapping mangrove communities compared to commercial images such as RE, and that the accuracy is greater when using VI. GEP images are very important tools to generate accurate and detailed large scale maps of mangrove communities and represent a great opportunity to move along in the challenge of identification, mapping and monitoring these valuable ecosystems.
The niche breadth of a species reflects its ability to inhabit different conditions, and to use different resources, hence, species with wider niche are expected to be more resilient to anthropogenic ...derived climate change. We estimated the niche breadth of all species of the genus Astrophytum from macro-environmental variables and measures of local habitat uses, in order to evaluate whether species having wider niche breadths are less prone to experience unsuitable conditions projected by the A1B and A2 scenarios of the IPCC for 2020 and 2050, and analyzed the implications of projections for the conservation of the genus Astrophytum. Our analysis suggests that most of populations of the four species will experience increasingly unsuitable conditions due to the increase of temperature and reduction in precipitation. The species less affected were those with wider niche breadth and situated in the middle of the latitudinal range and in the middle or lower extreme of the precipitation range for the genus (A. capricorne and A. myriostigma). Although the main threats for Astrophytum species come from the destruction of their habitats and activities as illegal extraction, climate change may reduce the chances for the regeneration of populations and the success of reintroduction programs.
•We explored the climate change effect on suitable conditions for the genera.•We analyzed implications of niche breadth in the vulnerability of species.•Most of populations could experiment unsuitable environmental conditions.•More abundant species with wider niche breadths are less affected.•Climate change threat the natural regeneration and success of conservation programs.
In community ecology, the knowledge of abiotic factors, that determine intraspecific variability in ecophysiological and functional traits, is important for addressing major questions, such as plant ...community assembly and ecosystem functioning. Mangroves have several mechanisms of resistance to salinity and most species exhibit some xeromorphic features in order to conserve water. Leaf area and stomatal density play an important role in maintaining water balance, and gas exchange is regulated by their aperture and density, two traits that vary intraspecifically in response to environmental conditions, such as water stress and salinity. In this study, we evaluated the effects of salinity on stomatal density, leaf area and plant size in R. mangle and we tested for associations among the three variables, across three sites along a natural salinity gradient in the Xel-Há Park, Quintana Roo, Mexico. We hypothesized that high salinity sites would produce smaller plants, with smaller leaves, and fewer stomata. Three sampling sites with different environmental conditions were chosen and salinities were monitored monthly. A total of 542 plants were tagged and tree heights and diameters were measured for each individual within each of the three sampling sites. Three leaves from 20 trees from each site were measured to determine leaf area. Stomatal densities were determined in each leaf using nail polish casts, examining ten 1 mm squares per leaf under an optical microscope. A principal component analysis was used to assess association between tree height, leaf area, and stomatal density for each plot. The salinity gradient was reflected in plant size, producing smaller plants at the higher salinity site. The largest leaves were found at the low salinity site (51.2 ± 24.99 cm2). Leaf length was not correlated to plant size (LL vs. tree height: r= 0.02, P= 0.8205; LL vs. trunk diameter: r= 0.03, P= 0.7336), so we concluded that leaf length is an environmentally plastic trait of red mangroves that may vary as a function of environmental conditions, such as hydric stress caused by elevated salinity. The larger leaves from the low salinity site had lower densities of stomata (65.0 stomata.mm2 SD= 12.3), and increasing salinities did not decrease stomatal density (intermediate salinity site: 73.4 stomata.mm2 SD= 13.5; high salinity site: 74.8 stomata.mm2 SD= 17.3). Our results confirm that stomatal density is inversely related to leaf area (r= -0.29, P < 0.001), especially leaf width (r= -0.31, P < 0.001), and that salinity may increase stomatal density by causing reduction of leaf size.
We studied the floral biology, floral visitors, levels of florivory, and mating system of Opuntia macrocentra in a population of ca. 300 individuals in order to describe what factors affect ...flower/fruit ratios. Blooming for the species occurred once a year during spring. Flowers were hermaphroditic, produced nectar, and remained open 6 to 9 h during a single day. Anther dehiscence starts at flower aperture and stigma receptivity starts approximately 1 h later. The most important floral visitors were solitary bees from the Anthophoridae family (genus Diadasia). Open- pollinated control and cross pollination treatments had the highest fruit set (96.8 ± 3.2% and 83.9 ± 6.7%, respectively), but fruit set for forced self-pollination treatment (77.4 ± 7.6%) did not differ from the cross-pollination treatment. Seed production was also highest in the open-pollinated treatment; the average number of seeds per fruit in the open-pollinated treatment was 40% higher than the cross-pollinated treatment and 64% higher than the self-pollinated treatment. The flowers were self-compatible and did not require a visitor to set fruit. Flower/fruit ratio was slightly above one over all pollination treatments (fruit ratios between 1.0–1.3), suggesting that almost all flowers turned into fruits. Outcrossing rates suggest a mixed mating system, but inbreeding depression was found for both fruit and seed set. Developing fruits were consumed by the caterpillar (Lepidoptera: Olycella subumbrella) and decreased fruit set from 20% to 100%. Florivory and inbreeding depression were the major factors that decrease fruit set for this species.
Variación en la densidad estomática, área foliar y tamaño de Rhizophora mangle (Malpighiales: Rhizophoraceae) a lo largo de un gradiente de salinidad en el Caribe Mexicano. Los manglares tienen ...varios mecanismos de resistencia salina y la mayoría de las especies presentan algunas características xeromórficas con el fin de conservar el agua. El tamaño de la hoja y la densidad de los estomas desempeñan un papel importante en el mantenimiento del equilibrio hídrico. El intercambio de gases puede mediarse mediante la regulación de la apertura de los estomas, así como el número de estomas sobre la epidermis, dos características que pueden variar intraespecíficamente en función las condiciones ambientales, tales como el estrés hídrico. Rhizophora mangle es una de las especies de mayor importancia en América del Norte y Sur, y de África occidental. El objetivo de este trabajo fue evaluar los efectos de la salinidad sobre la densidad de los estomas, el tamaño de la hoja y el tamaño de las plantas de Rhizophora mangle y determinar si existe una relación entre las tres variables, comparándose tres ambientes diferentes a lo largo de un gradiente natural de salinidad en Xel-Há, Quintana Roo, México. La hipótesis fue que los ambientes de alta salinidad producirían plantas más pequeñas, con hojas más pequeñas y menos estomas. Se seleccionaron tres sitios de estudio con condiciones ambientales diferentes y se midió la salinidad cada mes. Un total de 542 plantas fueron etiquetadas en los tres sitios, y se midió su altura y diámetro del tronco. Se recolectaron tres hojas de 20 árboles en cada uno de los sitios, y se obtuvo el área de cada hoja. La densidad estomática se midió mediante la técnica de microrelieve con barniz de uñas, observando diez 1 mm cuadrados bajo un microscopio óptico. Se utilizó un análisis de componentes principales para determinar la asociación entre altura de árbol, área de hoja y densidad estomática. El gradiente de salinidad se vio reflejado en el tamaño de las plantas, produciendo plantas más pequeñas en el sitio de alta salinidad. El largo de las hojas no se correlacionó con el tamaño de las plantas, por lo cual se concluyó que esta variable tiene plasticidad ambiental particular. Las hojas más grandes fueron encontradas en el sitio de baja salinidad y tuvieron densidades estomáticas menores. No se pudo observar que la densidad de estomas disminuyera con las altas salinidades. Estos resultados confirman que la densidad estomática es inversamente relacionada con el tamaño de la hoja, especialmente el ancho, y que la densidad estomática incrementa con la salinidad debido a la reducción del tamaño de hoja. Palabras clave: altura, área foliar, densidad estomática, estrés hídrico, manglar, plasticidad de hoja. In community ecology, the knowledge of abiotic factors, that determine intraspecific variability in ecophysiological and functional traits, is important for addressing major questions, such as plant community assembly and ecosystem functioning. Mangroves have several mechanisms of resistance to salinity and most species exhibit some xeromorphic features in order to conserve water. Leaf area and stomatal density play an important role in maintaining water balance, and gas exchange is regulated by their aperture and density, two traits that vary intraspecifically in response to environmental conditions, such as water stress and salinity. In this study, we evaluated the effects of salinity on stomatal density, leaf area and plant size in R. mangle and we tested for associations among the three variables, across three sites along a natural salinity gradient in the XelHá Park, Quintana Roo, Mexico. We hypothesized that high salinity sites would produce smaller plants, with smaller leaves, and fewer stomata. Three sampling sites with different environmental conditions were chosen and salinities were monitored monthly. A total of 542 plants were tagged and tree heights and diameters were measured for each individual within each of the three sampling sites. Three leaves from 20 trees from each site were measured to determine leaf area. Stomatal densities were determined in each leaf using nail polish casts, examining ten 1 mm squares per leaf under an optical microscope. A principal component analysis was used to assess association between tree height, leaf area, and stomatal density for each plot. The salinity gradient was reflected in plant size, producing smaller plants at the higher salinity site. The largest leaves were found at the low salinity site (51.2 + or - 24.99 cm.sup.2). Leaf length was not correlated to plant size (LL vs. tree height: r= 0.02, P= 0.8205; LL vs. trunk diameter: r= 0.03, P= 0.7336), so we concluded that leaf length is an environmentally plastic trait of red mangroves that may vary as a function of environmental conditions, such as hydric stress caused by elevated salinity. The larger leaves from the low salinity site had lower densities of stomata (65.0 stomata x mm.sup.2 SD= 12.3), and increasing salinities did not decrease stomatal density (intermediate salinity site: 73.4 stomata x mm.sup.2 SD= 13.5; high salinity site: 74.8 stomata x mm.sup.2 SD= 17.3). Our results confirm that stomatal density is inversely related to leaf area (r= -0.29, P < 0.001), especially leaf width (r= -0.31, P < 0.001), and that salinity may increase stomatal density by causing reduction of leaf size. Rev. Biol. Trop. 65 (2): 701-712. Epub 2017 June 01. Key words: leaf plasticity, leaf area, mangroves, tree height, stomatal densities, water stress.
Despite efforts for a complete phylogeny of Cactaceae, generic circumscription and species level relationships remain unsolved. Within Astrophytum one species is assigned to a different genus ...(Digitostigma) and two are often treated as a single species (A. myriostigma and A. coahuilense). Astrophytum is endemic to the Chihuahuan Desert, but may also be found in adjacent regions. We reconstructed the phylogeny to date the origin of clades and infer the biogeographic patterns of Astrophytum in order to understand the relationships between group members. Three sequences of chloroplast DNA (rbcL gene, trnL-trnF intergenic spacer, and trnK-matK region) were used with Bayesian and Maximum likelihood methods to generate a phylogeny. Divergence times for each node were estimated using an uncorrelated lognormal clock (BEAST) and inferred ancestral distribution using RASP. Astrophytum is monophyletic, with six species grouped in two main clades. Astrophytum caput-medusae (recognized as Digitostigma) is derived within Astrophytum. Individuals of A. myriostigma and A. coahuilense are grouped in independent clades, supporting their recognition as distinct species. Data suggest posterior diversification in the Late Miocene, during a transition to drier climates in North America. Occurrences of Astrophytum species outside of the Chihuahuan Desert are attributable to two recent independent events.
Premise of research. Plant sexuality evolves in response to genetic and ecological pressures that shape mating systems and floral traits. Comparing such systems and traits within phylogenies can show ...evolutionary trends in reproduction and floral morphology without the problems posed by the nonindependence of species. We compared sexual systems in seven species of the monophyletic genusAriocarpusto elucidate major differences in floral morphology and potential relationships between biogeographic rarity and reproductive traits. We hypothesized that floral morphology would be linked to outcrossing rates and that deviations from strict outcrossing and reduced fertility would be present in rare species.
Methodology. In one population per species, floral biology was detailed to characterize breeding systems, and mating systems were determined through pollination treatments. Discriminant analysis was used to identify floral traits that separate flowers into species. Phylogenetically independent contrasts were obtained to search for phylogenetic correlations between floral traits, and we inferred ancestral characters of floral traits across the phylogeny, using a maximum likelihood approach.
Pivotal results. Breeding systems are uniform acrossAriocarpusspecies, according to Cruden’s outcrossing index and pollen-to-ovule ratios. The outcrossing index obtained from pollination experiments showed that fiveAriocarpusspecies are predominantly outcrossers but that selfing can occur in two species. Most floral traits differed among species, and those related to male function separated flowers into species. Floral traits showed a conservative pattern of evolution within clades.
Conclusions. Breeding systems are uniform acrossAriocarpusspecies, with floral traits that promote outcrossing. The mating system inA. agavoidesandA. kotschoubeyanusdeparted from strict outcrossing;A. kotschoubeyanusflowers were smaller and had the least herkogamy. A conservative pattern of evolution in floral traits between sister species suggests that floral divergence inAriocarpusis restricted, but deviations from strict outcrossing can occur.
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