Background. There are no previous studies on the reproductive biology of the endemic and endangered cactus species Astrophytum ornatum. Questions. Is flowering continuous or episodic? What are the ...breeding and mating systems and what floral visitors are associated? and Does the reproductive success change over time? Study species. Astrophytum ornatum (Cactaceae). Study site and years of study. Observations from 2010 to 2011, in the highest density population of A. ornatum in Metztitlán Canyon (Hgo.). Methods. Monthly surveys and monitoring of reproductive structures. Tracking flowers in anthesis. Controlled pollinations to determine the mating system and determination of the Outcrossing Index (OCI), the pollen /ovule ratio and breeding system. Results. Astrophytum ornatum produced flower buds throughout the year, but 89.2% of them were aborted. Four events of ephemeral flowering population were presented per year. The species is self-incompatible and controlled pollinations indicated pollinator limitation of several bee species. The OCI indicates that the species is facultative xenogamy, and pollen/ovule ratio indicates obligate xenogamy. On average there were 54 seeds/fruit and individuals produced 4 fruits/year. Conclusions. The continuous production of buds had never been reported phenomenon for cacti. Intrapopulation bloom is one of the shortest recorded for the family and it produces high floral synchrony. The low number of seeds / fruit and flowers / individual, coupled with the narrow niche breadth of species and various anthropogenic factors place Astrophytum ornatumas a susceptible species to be extinct.
Antecedentes: No existen estudios precisos sobre la biología reproductiva de Astrophytum ornatum, especie endémica y en riesgo. Preguntas: ¿Cómo es la fenología de la especie? ¿Cuáles son los sistemas de cruza y apareamiento? y ¿Cuál es el éxito reproductivo? Especie de estudio: Astrophytum ornatum (Cactaceae). Sitio de estudio y fechas: Observaciones de 2010 a 2011 en la población más densa de A. ornatum en la Barranca de Metztitlán (Hgo. México). Métodos: Censos mensuales y seguimiento de estructuras reproductivas. Seguimiento de flores en antesis. Polinizaciones controladas para determinar el sistema de cruza y determinación del índice de entrecruza de Cruden (OCI) y de la relación polen/óvulo para estimar el sistema de apareamiento. Resultados: Astrophytum ornatum produjo botones florales todo el año pero el 89.2% de ellos fueron abortados. Se presentaron cuatro eventos efímeros de floración poblacional/año. La especie es autoincompatible y las polinizaciones controladas indicaron escasez de polinizadores (abejas). La especie es xenógama facultativa según el OCI o xenógama obligada por la relación polen/óvulo. En promedio se producen 54 semillas/fruto y 4 frutos/individuo/año. Conclusiones: La producción continua de botones florales es un fenómeno raramente reportado para cactáceas. La floración intrapoblacional constituye uno de los registros más cortos para la familia y produce una alta sincronía floral. El bajo número de semillas/fruto y de flores/individuo, aunado a la amplitud restringida del nicho de la especie y a diversos factores antropogénicos sitúan a Astrophytum ornatum como especie susceptible de extinción.
El género Mammillaria es de los más diversificados dentro de la familia Cactaceae, México es su centro de diversificación, y los estudios que analicen detalladamente los ciclos de vida de especies ...pertenecientes a este género son necesarios para determinar el estado de sus poblaciones y planear estrategias de conservación. Mammillaria humboldtii (C. Ehrenb, L.) es una especie endémica de Hidalgo, actualmente se encuentra en la categoría de “amenazada” por la NOM-059-SEMARNAT-2010 y en “peligro crítico” por la UICN. Empleamos modelos de proyección matricial para evaluar el estado de conservación de una población de M. humboldtii dentro de la Reserva de la Biosfera Barranca de Metztitlán, durante dos años (2012-2013). Se construyó una matriz de transición para poder calcular la tasa de crecimiento poblacional (?); se simularon los cambios en los elementos de la matriz que corresponden a la permanencia de banco de semillas, transición de semilla a plántula y permanencia de adultos. La tasa de crecimiento poblacional ? es de 0.8044 (0.754-0.846) indicando que la población decrece un 20 %. El proceso demográfico al que ? es más sensible fue la estasis (S = 68.35 %), seguido del crecimiento (G = 18.09 %). El valor reproductivo más alto fue el de la categoría adulto 3, las simulaciones mostraron que al incrementar el establecimiento de plántulas y la permanencia de adultos aumenta el valor de ? > 1, estos procesos son los principales cuellos de botella de la dinámica y crecimiento poblacional. Cualquier estrategia de manejo para la conservación de esta especie in situ deberá considerar el monitoreo a largo plazo de la población así como asegurar el establecimiento de plántulas y sobrevivencia de los adultos.
The dynamics of plant populations in arid environments are largely affected by the unpredictable environmental conditions and are fine‐tuned by biotic factors, such as modes of recruitment. A single ...species must cope with both spatial and temporal heterogeneity that trigger pulses of sexual and clonal establishment throughout its distributional range. We studied two populations of the clonal, purple prickly pear cactus, Opuntia macrocentra, in order to contrast the factors responsible for the population dynamics of a common, widely distributed species. The study sites were located in protected areas that correspond to extreme latitudinal locations for this species within the Chihuahuan Desert. We studied both populations for four consecutive years and determined the demographic consequences of environmental variability and the mode of reproduction using matrix population models, life table response experiments (LTREs), and loop and perturbation analyses. Although both populations seemed fairly stable (population growth rate, λ∼1), different demographic parameters and different life cycle routes were responsible for this stability in each population. In the southernmost population (MBR) LTRE and loop and elasticity analyses showed that stasis is the demographic process with the highest contributions to λ, followed by sexual reproduction, and clonal propagation contributed the least. The northern population (CR) had both higher elasticities and larger contributions of stasis, followed by clonal propagation and sexual recruitment. Loop analysis also showed that individuals in CR have more paths to complete a life cycle than those in MBR. As a consequence, each population differed in life history traits (e.g., size class structure, size at sexual maturity, and reproductive value). Numerical perturbation analyses showed a small effect of the seed bank on the λ of both populations, while the transition from seeds to seedlings had an important effect mainly in the northern population. Clonal propagation (higher survival and higher contributions to vital rates) seems to be more important for maintaining populations over long time periods than sexual reproduction.
Clonal structure in clonal plants can affect sexual reproduction. Individual ramets can decrease reproduction if their neighbors are ramets of the same genet due to inbreeding depression or ...self-incompatibility. We assessed ramet reproductive success in the partial self-incompatible
Ferocactus robustus
(Cactaceae) as a function of floral display size in focal ramets and floral display size and clonal structure of their reproductive neighborhoods. Ramets were labeled, sized in number of stems, mapped and genetically identified through RAPD markers in one population. A pollen dispersal area of 15-m radius was established for each ramet to determine the clonal diversity in the neighborhoods. Flower production and fruit set were counted on a monthly basis during one reproductive season as a surrogate of ramet fitness. We expected a decrease in individual ramet reproductive success as a function of the number of reproductive ramets of the same genet in the neighborhood. A total of 272 sampled ramets revealed 116 multilocus genotypes, showing high clonal diversity in the population (
G
/
N
= 0.43,
D
= 0.98). Clonal diversity of neighborhoods ranged from 0.06 to 1 and fruit set varied from 0 to 76.9%. Individual ramet reproductive success was influenced by (1) mate availability, (2) floral display size of a genet within the reproductive neighborhood, and (3) the proportion of distinguishable genotypes. Floral display size of genets and ramets coupled with the genetic diversity within the reproductive neighborhood determines the low sexual reproduction in
F. robustus.
La producción de semillas y el reclutamiento en las especies dependen en parte de factores reproductivos, tales como el comportamiento floral, la fenología de la floración, la producción de gametos y ...néctar, los sistemas de cruzamiento y de apareamiento, y la densidad poblacional. En este trabajo se estudia la biología floral, producción de néctar y polinización de Mammillaria huitzilopochtli D.R.Hunt en condiciones ex situ para sentar las bases que pueden ayudar a determinar el riesgo de extinción de la especie dado su sistema de apareamiento y éxito reproductivo. La floración de M. huitzilopochtli abarca cuatro meses (septiembre a diciembre), de antesis diurna, con longevidad por flor de alrededor de seis días, se presentó baja la producción de néctar (2.02 μl) y éste sólo se detectó en el 39% de las flores. La especie presenta un sistema de entrecruza xenógamo facultativo, con una relación polen:óvulo de 1,048. La producción de semillas por fruto es variable y baja con relación al número de óvulos promedio (35%). Existen muy pocos trabajos de biología floral en el género Mammillaria, pero al compararla con otras cactáceas, el comportamiento floral es similar a las especies de polinización melitófila como Echinocactus, Grusonia y Opuntia . La longevidad floral es la más prolongada de las reportadas y, el dimorfismo en la producción de néctar y el asentamiento de frutos vacíos no se había registrado para esta especie. El sistema de apareamiento xenógamo facultativo y el entrecruzamiento son frecuentes en las cactáceas raras y en peligro de extinción. Su condición de xenógama, la amplia varianza en el número de semillas por fruto y la incapacidad para clonar incrementa su riesgo.
La invasión de especies no autóctonas es una de las principales amenazas para la conservación de la biodiversidad y para la provisión de servicios ecosistémicos. Uno de los ecosistemas más ...vulnerables a escala mundial por la presencia de especies exóticas invasoras (EEI) es el bosque de manglar, ya que estas pueden desestabilizar la estructura y función de las redes tróficas y reducir su productividad, principalmente por competencia y depredación de especies nativas. En este estudio se realizó un análisis en los sistemas de información de biodiversidad y la literatura científica especializada para determinar la presencia de EEI en los bosques de manglar de las reservas de la biosfera Ría Celestún y Ría Lagartos ubicadas en la península de Yucatán, México; se identificó el nivel de riesgo de las EEI de acuerdo con el método de evaluación rápida de invasividad, y se generó información sobre las implicaciones de las EEI en los bosques de manglar. Entre las dos áreas naturales protegidas (ANP), se encontró la presencia de 16 EEI, de las cuales, 56.25% tienen valor de riesgo de invasividad “muy alto” y 43.75% riesgo de invasividad “alto”, lo que significa una alerta de peligro para los bosques de manglar de las ANP. La información generada en este estudio servirá de base para el planteamiento de estrategias de gestión para la atención de EEI y sobre la conservación de los bosques de manglar en las ANP.
The invasion of non-native species is one of the main threats to biodiversity conservation and the provision of ecosystem services. Mangroves are one of the most vulnerable ecosystems worldwide due to invasive alien species (IAS), as they can destabilize the structure and function of trophic webs and reduce their primary productivity, mainly through competition and predation of native species. In this paper, an analysis of biodiversity information systems and scientific literature were used to determine the presence of IAS within the mangrove forests of the Ria Celestún and Ría Lagartos biosphere reserves in the Yucatan Peninsula, Mexico; the level of risk of IAS was identified according to the rapid invasiveness assessment method, and information was generated on the implications of IAS in mangrove forests. In both natural protected areas (NPAs), 16 IAS were found, of which 56.25% had a "very high" invasiveness risk value, and 43.75% had a “high” invasiveness risk, which implies a danger alert for mangrove forests in the NPAs. The information generated in this study can be used to identify strategies for managing IAS and the conservation of mangrove forests in NPAs.
Fuentes-Agueda, S.A.; Gallegos, M.E.; Mandujano, M.C., and Golubov, J., 2023. Contrasting growth and establishment of Thalassia testudinum along a cover gradient in the Gulf of Mexico. Journal of ...Coastal Research, 39(4), 653–662. Charlotte (North Carolina), ISSN 0749-0208. Seagrasses are important for coastal ecosystem health and have significant economic benefits; however, they are undergoing important negative changes worldwide. The seagrass Thalassia testudinum comprises one of the main elements in submerged aquatic vegetation (SAV) habitats, and it grows in monospecific and mixed meadows along the continental shelf of the Gulf of Mexico. In this study, T. testudinum monospecific and mixed meadows were monitored over a 2 year period to identify the abiotic and biotic conditions that may correlate with population parameters through the plastochron index (PI). Plants found in monospecific meadows had larger rhizomes and more flowers in comparison to those in mixed meadows, while the latter produced more leaves and larger shoots. The annual rate of change in biomass (Br) of T. testudinum in the monospecific meadow was 1.15 ± 0.03, which was slightly higher than that in the mixed meadow, with a value of 1.12 ± 0.03. T. testudinum in monospecific meadows tended to exhibit increased sexual reproduction, while vegetative growth and clonal reproduction were more common in mixed meadows. The results highlight that T. testudinum life-history strategies and establishment are affected by both biotic and abiotic factors like depth, temperature, and water nutrients.
Correct species identification is critical for studies on biodiversity, ecology, and conservation. Determining Opuntia s.s. species is difficult because they have similar traits and are ...phenotypically plastic. Taxonomic keys are based on vegetative traits rather than reproductive ones such as flowers, because they are assumed to be too similar. We analyzed morphometric characteristics of flowers and cladodes over 6 years to determine which of these is most useful for differentiating Opuntia species from the Chihuahuan Desert. For each species ( Opuntia robusta H.L. Wendl. ex Pfeiff., O. cantabrigiensis Lynch, O. tomentosa Salm-Dyck, and O. streptacantha Lem.), we tagged 20 hermaphroditic and 40 dioecious plants (totaling 100) from 2014 to 2020 to complete the sample size of flowers and cladodes. Seventeen morphometric characters were measured for new cladodes and 15 for flowers, and discriminant analysis was applied to determine which traits enabled species delimitation. Six of the 17 cladode characteristics combined explained 89% of the variation, while 9 floral characteristics combined explained 94% of the variation. Floral morphometrics proved to be very useful to accurately differentiate species and should be included, in addition to cladodes, in future taxonomic studies. Here, we provide the first taxonomic key that includes floral traits to identify Opuntia and a new description of each studied species.
Mexico’s invasive species plan in context Golubov, Jordan; Aguirre-Muñoz, Alfonso; Mendoza, Roberto ...
Science (American Association for the Advancement of Science),
04/2017, Letnik:
356, Številka:
6336
Journal Article
Reproductive systems are life attributes important in defining the demography and genetic constitution of invasive alien species populations. We describe the phenology, floral behavior and floral ...visitors in Mexican populations of Leonotis nepetifolia considered invasive in America, Asia and Oceania. The mating system was determined through pollination experiments and, with a morphological analysis of flowers (outcrossing index, OCI) and pollen/ovule ratio, the breeding system was evaluated. Germination of 1 and 2‐year‐old seeds was tested to assess the potential characteristics of germination. Leonotis nepetifolia was reproductive for 7 months (June to December) and tended towards a specific season during autumn. Anthesis lasted 36 hr with protogyny and no hercogamy, with floral visitors of Apodiformes, Hymenoptera, Lepidoptera and Thysanoptera. Pollination experiments indicated a mixed mating system, whereas the OCI and the pollen/ovule ratio pointed towards a facultative xenogamous breeding system. Seed production was high (1,445 ± 132 seeds/plant); the seeds had potential longevity and were neutral photoblastic. One‐year‐old seeds germinated slightly later (x¯ = 2.6 ± 0.11 days) than 2‐year‐old seeds (x¯ = 1.9 ± 0.02 days), both synchronously (IS1yr = 0.88 ± 0.03 and IS2yr = 0.82 ± 0.02). Germination percentage for 1‐year‐old seeds was lower (55.33 ± 4.40%) than that of 2‐year‐old seeds (94.18 ± 0.59%), suggesting a potential longevity of the seeds in an optimal environment. Reproductive characteristics, such as wide reproductive period, mixed breeding system, copious seed production, seeds with potential longevity, and quick and synchronic germination in different light conditions, favor the invasive capacity of Leonotis nepetifolia.
Leonotis nepetifolia is considered an invasive species in America, Asia and Oceania. In a population of Mexico, we evaluate and describe different reproductive characteristics of the species. Reproductive characteristics, such as wide reproductive period, mixed breeding system, copious seed production, seeds with potential longevity, quick and synchronic germination in different light conditions, favor its invasive capacity. Understanding these characteristics could help design strategies for their management.
PDF
