Astrophytum is one of most collected genera in the cactus family. Around the world several species are maintained in collections and yearly, several plants are taken from their natural habitats. ...Populations of Astorphytum capricorne are found in the northern Chihuahuan desert, Mexico, and as many endemic cactus species, it has a highly restricted habitat. We conducted a demographic study from 2008 to 2010 of the northern populations found at Cuatro Ciénegas, Mexico. We applied matrix population models, included simulations, life table response experiments and descriptions of the population dynamics to evaluate the current status of the species, and detect key life table stages and demographic processes. Population growth rate decreased in both years and only 4% individual mortality can be attributed to looting, and a massive effort is needed to increase seedling recruitment and reduce adult mortality. The fate of individuals differed between years even having the same annual rainfall mainly in accentuated stasis, retrogression and high mortality in all size classes, which coupled with low seed production, no recruitment and collection of plants are the causes contributing to population decline, and hence, increase the risk in which A. capricorne populations are found. Reintroduction of seedlings and lowering adult mortality are urgently needed to revert the alarming demographic condition of A. capricorne populations.
•We used population matrix models to determine the population status of a cactus.•We examine the effect of seed bank and seedling establishment on population growth.•The population showed high mortality in all size classes and low fecundity.•4% of the plants were illegally collected during our 3 yr study period.•Based on the population growth rate, the species is critically endangered.
Seed aggregation in latrines of rabbits is a little-studied process that may contribute substantially to seed dispersal and survival. We located Juniperus deppeana trees and the latrines used by the ...endemic Mexican cottontail rabbit Sylvilagus cunicularius within a 1 ha fragment of J. deppeana-dominated forest and evaluated their patterns of aggregation as microhabitats used by cottontail rabbits to consume the J. deppeana galbulus (fleshy cones) or to deposit their pellets with defecated seeds. Based on mean latrine area, we marked a 2 m × 2 m plot centred on the base of every tree or latrine within the study site. We counted all pellets within each plot and analysed them for the presence of seeds of Juniperus or any other species. We found seeds in 13% of all pellets, mainly those deposited in the latrines. If seeds are scarified by passing through the intestinal tract, seed germination in latrines may increase the probability of survival and establishment. Thus, the community structure and density could change in time as rabbits are changing the places where they place their latrines.
http://zoobank.org/urn:lsid:zoobank.org:pub:372FEED4-5DFF-4144-A384-4FB30F480A26
Nurse-protégé interactions facilitate seedling establishment of many cacti species and might promote spatial aggregation of plants. In June 2014, we analyzed the spatial distribution pattern with ...Ripley's K-function and the possible association of Astrophytum myriostigma with nurse plants in two populations (Rioverde and Pozas, San Luis Potosí, Mexico). We estimated canopy cover of perennial plant species with a logarithmic scale method and determined the association, size, and orientation of A. myriostigma in relation to nurse plants. Astrophytum myriostigma had an aggregated distribution pattern; approximately 50% were associated with nurse plants at Rioverde and 63% at Pozas, with Hechtia glomerata (Bromeliaceae) being the main nurse plant species in both populations. Cacti associated with nurse plants at Pozas were larger than those not associated, and they did not have any significant orientation in relation to the nurse plant crown. In contrast, the size of associated and nonassociated cacti at Rioverde was similar, but they were established significantly more frequently under the north side of the nurse plant. The association of A. myriostigma with nurse plants is facultative, through either nurse plant protection or open spaces, likely related with abiotic nurses. Understanding nurse plant associations will help target key species for conservation and identify the most likely associations to increase the survival of reintroduced individuals.
The introduction of the honey bee, Apis mellifera L. (Hymenoptera: Apidae), into the arid environments of Mexico has affected the behavioral ecology of native bees. We described the behavioral ...repertoire and interactions between A. mellifera and the native bee Lithurgus littoralis Cockerell (Hymenoptera: Megachilidae) on Opuntia huajuapensis Bravo (Cactaceae) flowers in a semiarid environment. We filmed the bees in 150 cactus flowers to obtain the diversity of behaviors and their durations and thereby quantify the interactions. The behavior accumulation curve (Clench model) showed differences in the behavioral repertoire between the 2 bee species and between the sexes of L. littoralis. We found that A. mellifera and L. littoralis females invested more time in feeding behavior than L. littoralis males and recorded a wider repertoire of agonistic behaviors in male compared with female bees. Native male bees often perched in flowers and were inactive for long periods. The results indicate a possible interference competition between native and non-native bee species that are visiting the flowers of O. huajuapensis.
Insect-pollinated plants offer nectar as the main reward, which influences the preference of flower visitors. We describe the feeding behavior of the exotic bee Apis mellifera (L.) (Hymenoptera: ...Apidae) and the flower fly Lycastrirhyncha nitens (Bigot) (Diptera: Syrphidae) on tristylous flowers of Pontederia sagittata (C. Presl) (Commelinales: Pontederiaceae) in relation to temporal nectar availability. The production of this resource was similar between floral morphs but there were temporal variations during the anthesis period, in a coincidence with a higher number of visitors and activity of bees and flies. The dynamics of nectar production could be related to the feeding behavior of these insects despite the similarity in daily nectar volume produced in all the 3 types of flowers. The variations of nectar feeding may affect the transportation of pollen among the 3 floral morphs. Key Words: Apis mellifera; fower fy; tristyly; behavior; nectar Las plantas polinizadas por insectos ofrecen el nectar como la principal recompensa que infuye las preferencias de los visitantes forales. Describimos el comportamiento de alimentacion de la abeja exotca Apis mellifera (L.) (Hymenoptera: Apidae) y la mosca de las fores Lycastrirhyncha nitens (Bigot) (Diptera: Syrphidae) en las fores tristlicas de Pontederia sagitata (C. Presl) (Commelinales: Pontederiaceae) en relacion con la disponibilidad temporal de nectar. La produccion de este recurso fue similar entre los morfos forales pero hubo variacion temporal durante el periodo de antesis, en coincidencia con un mayor numero de visitantes y actvidad de abejas y moscas. La dinamica en la produccion de nectar podria estar relacionada con el comportamiento de alimentacion de estos insectos a pesar de la similitud en los valores de volumen de nectar producido por los tres tpos de fores. Las variaciones en el consumo de nectar podria afectar el transporte de polen entre los tres morfos forales. Palabras Clave: Apis mellifera; mosca de las fores; tristlia; comportamiento; nectar
Insect-pollinated plants offer nectar as the main reward, which influences the preference of flower visitors. We describe the feeding behavior of the exotic bee Apis mellifera (L.) (Hymenoptera: ...Apidae) and the flower fly Lycastrirhyncha nitens (Bigot) (Diptera: Syrphidae) on tristylous flowers of Pontederia sagittata (C. Presl) (Commelinales: Pontederiaceae) in relation to temporal nectar availability. The production of this resource was similar between floral morphs but there were temporal variations during the anthesis period, in a coincidence with a higher number of visitors and activity of bees and flies. The dynamics of nectar production could be related to the feeding behavior of these insects despite the similarity in daily nectar volume produced in all the 3 types of flowers. The variations of nectar feeding may affect the transportation of pollen among the 3 floral morphs.
The diverse offspring of clonal species differ in their dispersability, influencing genotypic diversity and clonal structure. Here, we determined dispersal patterns and their impact on genetic ...structure in Opuntia microdasys, a self‐incompatible cactus with three dispersal units (one sexual and two clonal). We analyzed dispersal, using experiments at three populations, and assessed multilocus genotypes (ISSR markers) of all individuals in 10 clumps per population with known reproductive origin (sexual or clonal). Genotype of all samples, population structure, and migration between clumps and populations were assessed with GenAlEx and GenoDive, assuming higher genotypic diversity and migration when sexual reproduction is more frequent. We determined the most likely number of genetic clusters with STRUCTURE and GENELAND. Dispersal differed among populations; primary dispersal occurred at short distances and was farthest on steep slopes, and dispersal distance increased after secondary dispersal. Clumps had 116 different multilocus genotypes in three spatially explicit genetic clusters. We detected genetic structure at small scale, genotypic diversity among clumps varied between populations; diversity decreased while clonal dominance increased, and the most variation occurred among clumps. Genetic structure was moderate, suggesting gene flow by seed dispersal allows slight differentiation among population at large scales. Genetic diversity within clumps was the lowest because dispersal of clonal propagules was limited and caused genotypic dominance at local scale. However, the combined dispersal pattern of sexual and clonal dispersal units is fine‐tuned by environmental factors, generating a range of genetic diversity among clusters and populations. This pattern suggests that genetic structure of clonal plants is more dynamic than thought, and dispersal of different types of offspring affects genetic structure at many scales.
We study the effect of clonal and sexual propagule dispersal on the genotypic diversity of a clonal cactus and estimate migration rates at different scales. Plants were sampled and genotyped from each of three populations to determine multilocus genotypes based on ISSRs markers and analyzed with STRUCTURE and Geneland. Clonal offspring with limited mobility increased genetic structure, and three main genetic clusters correspond to the spatial location. Migration is mediated by sexual propagules among populations.
Resumen: El conejo Sylvilagus floridanus (J.A. Allen, 1990) y la liebre Lepus callotis (Wagler, 1830), que cohabitan en la zona semiárida del valle de Perote, están bajo la continua presión de ...cambios en su hábitat por el impacto producido por incendios de tipo antrópico. Investigamos cómo el comportamiento de formación de letrinas de estos lepóridos difiere entre sitios con y sin exposición al incendio y cuáles son sus características de tamaño y composición. Nuestros resultados mostraron que el tamaño de las letrinas difiere entre conejos y liebres, y además entre sitios, ya que el sitio perturbado es donde las letrinas fueron más heterogéneas en tamaño. También registramos la presencia de letrinas mixtas en donde los conejos y liebres depositan mayor cantidad de grupos fecales después de 6 meses de haber ocurrido el incendio. Mostramos que S. floridanus y L. callotis tienen amplia plasticidad para aclimatarse a un hábitat perturbado por incendio y usan el hábitat perturbado a pesar de la pérdida temporal de la cobertura vegetal.
The introduction of the honey bee, Apis mellifera L. (Hymenoptera: Apidae), into the arid environments of Mexico has affected the behavioral ecology of native bees. We described the behavioral ...repertoire and interactions between A. mellifera and the native bee Lithurgus littoralis Cockerell (Hymenoptera: Megachilidae) on Opuntia huajuapensis Bravo (Cactaceae) flowers in a semiarid environment. We filmed the bees in 150 cactus flowers to obtain the diversity of behaviors and their durations and thereby quantify the interactions. The behavior accumulation curve (Clench model) showed differences in the behavioral repertoire between the 2 bee species and between the sexes of L. littoralis. We found that A. mellifera and L. littoralis females invested more time in feeding behavior than L. littoralis males and recorded a wider repertoire of agonistic behaviors in male compared with female bees. Native male bees often perched in flowers and were inactive for long periods. The results indicate a possible interference competition between native and non-native bee species that are visiting the flowers of O. huajuapensis.
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