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.
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.
Invasion of Kalanchoe by clonal spread Guerra-García, Azalea; Golubov, Jordan; C. Mandujano, María
Biological invasions,
06/2015, Letnik:
17, Številka:
6
Journal Article
Recenzirano
Kalanchoe delagoensis
,
K. daigremontiana
and their hybrid (Houghton’s hybrid) are invasive in tropical regions. One outstanding feature of these Madagascan succulent plants is the growth of clonal ...propagules from the margin of their leaves. Using eight microsatellite loci, we estimated the genetic diversity of introduced populations of these species and their hybrid in Mexico. For
K. daigremontiana
and Houghton’s hybrid, we registered one multilocus genotype in all populations, which were separated by several hundred km. The same occurred in
K. delagoensis
populations where only four multilocus genotypes were present (A, B, C and D), although genotype A accounted for 86 % of all screened individuals of that population. The other three genotypes were in low frequencies and did not present new alleles, indicating that they are very likely derived by sexual recombination. However, sexual reproduction seems not to have occurred in the other populations. The presence of just one genotype of the hybrid suggests that hybridization between
K. delagoensis
and
K. daigremontiana
is unlikely, but we cannot discard it because of the absence of private alleles. The lack of genotypic diversity suggests that the invasion by these two species and the hybrid occurred from the introduction of one genotype, and have expanded by clonal growth and human mediated dispersal.
The maintenance of interactions between plants and their floral visitors depends on factors such as resource variability, seasonality, and population dynamics. Changes in water availability along ...with different types and levels of anthropogenic disturbance may influence how plants and pollinators interact, especially in arid environments.
In a semi‐arid area of the southernmost Chihuahuan Desert (Mexico), we surveyed bee–plant interactions in the dry and rainy season at sites that differed in disturbance type. We used a mutualistic network approach to analyse our data.
We collected 946 bee individuals belonging to 32 bee species, almost a third of the total richness previously reported for Querétaro state. We detected a strong impact of seasonality on the structure of ecological interactions, with more complex and robust interactions among bee and plant species in the rainy season.
We did not find statistical support for a relationship among disturbance, nestedness, or niche overlap. We did find disturbance negatively affected plant robustness to secondary extinctions.
Four plants: Echinocactus platyacanthus, Opuntia stenopetala, Senna wislizeni var. painteri and Cylindropuntia imbricata comprised the core species that were primarily responsible for the resilience of the bee communities. The following bees conformed the generalist core of species: Diadasia rinconis, Lasioglossum (Dialictus) sp. 1, Apis mellifera, and Augochlorella pomoniella.
Overall, network nestedness and robustness differed significantly between seasons but not among sites with different levels of disturbance.
There is a strong impact of seasonality on the structure and assembly of bee–plant ecological interactions, promoting a more complex and robust system in the rainy season.
We did not find statistical support for a relationship among disturbance, nestedness, or niche overlap. However, we found that disturbance negatively affected plant robustness to secondary extinction.
The plants Echinocactus platyacanthus, Opuntia stenopetala, Senna wislizeni var. painteri and Cylindropuntia imbricata act as core species for the maintenance of resilient bee communities. The following bees formed the generalist core of species: Diadasia rinconis, Lasioglossum(Dialictus) sp. 1, Apis mellifera, and Augochlorella pomoniella.
Overall, network nestedness and robustness differed significantly between seasons but not among sites with different levels of disturbance.
A nurse–protégé relationship is a frequent facilitation interaction in deserts that allows the recruitment of new individuals of many species. Our aim was to evaluate the relationship of Echinocereus ...enneacanthus during its life cycle and its nurse plants in the brousse tigrée (tiger bush) vegetation of the Chihuahuan Desert. The population structure of the cactus is skewed toward adult stages, which are commonly found in the bare areas of the brousse tigrée, whereas juveniles are located in the vegetated bands. The vegetation structure and the nurse–protégé relationship were determined using censuses of 19 permanent plots monitored between 2008 and 2019. The differential association of E. enneacanthus with potential nurse plants was evaluated using an interaction network, under the hypothesis of strict association of the seedlings and juveniles with nurse species. In addition, χ2 tests and standardized residuals were fitted among likely nurse species, weighted by the cover of the nurse and of the areas without vegetation. The study species, as well as the nurse plants, had an aggregated distribution pattern. The interaction network showed that the frequency of the association with nurse plants decreased as the size of the protégé individuals increased. At the same time, there were differences in the establishment of E. enneacanthus under particular nurse plants; Prosopis glandulosa and Hilaria mutica were the most important. The nurse–protégé relationship for seeds and seedlings is integral to the vegetation bands of the brousse tigrée.
A nurse–protégé relationship is a frequent facilitation interaction in deserts that allows the recruitment of new individuals of many species.
We evaluate the relationship of Echinocereus enneacanthus during its life cycle and its nurse plants in the brousse tigrée (tiger bush) vegetation of the Chihuahuan Desert.
Population structure is skewed toward adult stages, which are found in bare areas of the brousse tigrée, while juveniles are located in the vegetated bands associated with a nurse.
The nurse–protégé relationship for seeds and seedlings is integral to the vegetation bands of the brousse tigrée.
Se propone a Mammillaria cielensis (Cactaceae), como una especie nueva de la Reserva de la Biosfera “El Cielo” (RBC) en Tamaulipas, México. Es morfológicamente muy similar a M. zublerae Repp., de la ...cual difiere en el tamaño del tallo, la forma redondeada del ápice, los tubérculos de menor tamaño y glabros, aréolas con lana blanca, las espinas radiales y centrales más numerosas y ligeramente más cortas, frutos de diferente color y tamaño, la semilla de mayor tamaño, con testa porosa y el hilo de mayores dimensiones. Su distribución conocida se restringe al bosque de pino encino en el área de la RBC, al sur del estado de Tamaulipas, México. Se presenta una comparación con las especies afines.
The dynamics of plant populations are often limited by the early stages in their life cycles. However, information regarding seed bank dynamics and how these may influence the whole life cycle of ...plant species is remarkably scarce or not considered explicitly. This lack of knowledge is due mainly to the challenges in quantifying seed vital rates. Studies of arid land plant species have historically been focused on the drivers of sporadic recruitment. However, little attention has been given to the demographic consequences of early developmental stages, and how seed banks affect their dynamics. Here, we evaluate the effects of seed bank survival and seedling recruitment vital rates on the population dynamics and viability of 12 columnar cacti species. Recent evidence suggests that cacti seeds may remain viable for the short‐term. We assess how changes in the vital rates of these processes and the inclusion of a seed bank affect population growth rate (λ). We found that a seed bank in the examined matrix population models significantly increased λ as well as the vital rate elasticities of λ to growth and fecundity, whereas that of overall survival decreased. Our numerical simulations showed that seed survival had a more considerable effect on λ than seedling recruitment and establishment. We suggest that the seed bank may explain the structure and population dynamics. Thus, we reconsider that this early stage in demographic models will generate more informed decisions on the conservation and management of columnar cacti.
This manuscript reports results on the evaluated effects of seed bank survival and seedling recruitment vital rates on the population dynamics and viability of 12 columnar cacti species.
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