Studies of habitat selection are crucial for the conservation of threatened amphibians. Wild salamanders are often distributed near rocks or vegetation, which provide shelter. However, nothing is ...known about habitat selection of the Mexican axolotl (
Ambystoma mexicanum
), an endangered salamander of great cultural and ecological value. This study aims to test the relationship between vegetation presence and the distribution of captive-raised axolotls in two systems: a closed canal in their native ecosystem (
n
= 10) and an artificial canal within a zoological park (
n
= 6). We used radio-telemetry to analyse the hourly distribution and movement patterns of axolotls in each study site during 72-h observational periods. We found that movement patterns and microhabitat selection were related to vegetation coverage and diurnal and nocturnal periods. Sex and age had no effect in habitat selection. Axolotls in both study sites preferred vegetated microhabitats, but in Xochimilco this preference was only significant during daytime when they were less active. These habitat-specific patterns of spatial distribution may represent behavioural strategies for reducing predation. The first approach of behavioural insights from this study will inform the construction of refuges to reduce the alarming depletion of axolotls in the wild.
The probability of Blue‐footed Booby Sula nebouxii fledglings becoming reproductive adults is maximal when one parent is old and the other young, and minimal when both are old or young. No mechanism ...has been identified to explain this pattern, but here we showed that nestlings with different‐aged parents are the least infested with ticks. This result constitutes preliminary confirmation of the hypothesis that the effect of combined parental ages on probability of recruitment is mediated by offspring immunocompetence. The contribution of immunocompetence and parental care to these parental age effects needs to be unravelled.
Parasites are a major risk for group‐living animals and seabirds are notoriously susceptible to ectoparasite infestations because they commonly nest in dense colonies. Ticks parasitize seabirds ...across all biogeographical regions and they can be particularly harmful to nestlings, but the ecological factors that affect their transmission to chicks are little studied and poorly understood. Here we show that abundance of tick larvae in blue‐footed booby Sula nebouxii broods varies with local nest synchrony and density, and also with habitat structure: abundance increased with local breeding synchrony, was linearly and quadratically related to local nest density, and was highest toward the southern end of the study area which has suitable (boulder‐rich) habitat for ticks. Also, with increasing chick age infestation first increased and then declined. The results of this study highlight how local physical and social environmental factors influence infestation of seabird nestlings by ticks.
The function of female birds’ extra-pair (EP) behavior has remained an unresolved question in ornithology and behavioral ecology for > 30 yr. The genetic compatibility hypothesis (GCH) proposes that ...females benefit by acquiring biological sires that yield more heterozygous, and therefore fitter, offspring than their social mates. We used ten polymorphic microsatellite loci to test GCH predictions and its assumption that fitness increases with heterozygosity in blue-footed boobies Sula nebouxii, a long-lived tropical seabird. Our predictions were not supported. Heterozygosity was uncorrelated with quality indicators (fledging probability, fledgling or adult body size or mass, adult ornamentation, mean breeding success). Females were no more likely to have EP behavior or chicks when their social mates were less heterozygous or compatible, nor were EP males more heterozygous or compatible than the males they cuckolded. Finally, EP chicks were no more heterozygous than within-pair chicks overall or in half-sib comparisons, nor were within-pair chicks from all-within-pair nests more heterozygous that those with EP nest-mates. There are both methodological and biological explanations for these consistently negative results. Inadequate sample size is possible but unlikely, since our samples were comparable or larger than those of similar studies with significant findings. Lack of identity disequilibrium (within-individual heterozygosity correlation) among our marker loci could be responsible, and suggests either insufficient marker coverage or lack of inbreeding, bottleneck, and/or admixture. An independent social pedigree revealed infrequent inbreeding, suggesting that pressure on females to select sires that maximize offspring heterozygosity may be genuinely lax. Alternatively, it is possible that the GCH is only upheld when selection on young is strongest; this would not be detected in our sample, which was taken during an extremely productive year. Whatever their cause, our results expand the taxonomic breadth of avian EP behavior analyses and should be considered in future evaluations of the GCH.
Long‐term multigenerational experimental simulations of climate change on insect pests of economically and socially important crops are crucial to anticipate challenges for feeding humanity in the ...not‐so‐far future. Mexican bean weevil Zabrotes subfasciatus, is a worldwide pest that attacks the common bean Phaseolus vulgaris seeds, in crops and storage. We designed a long term (i.e., over 10 generations), experimental simulation of climate change by increasing temperature and CO2 air concentration in controlled conditions according to model predictions for 2100. Higher temperature and CO2 concentrations favored pest's egg‐to‐adult development survival, even at high female fecundity. It also induced a reduction of fat storage and increase of protein content but did not alter body size. After 10 generations of simulation, genetic adaptation was detected for total lipid content only, however, other traits showed signs of such process. Future experimental designs and methods similar to ours, are key for studying long‐term effects of climate change through multigenerational experimental designs.
This multigenerational simulation of climate change demonstrates how an economically important pest of the bean seeds; the Mexican bean weevil, will be leaner, fitter and show genetic resilience under the conditions predicted for 2100.
The evolution of remating and prolonged pair bonds in animals has generally been explained in terms of improved coordination and cooperation between familiar individuals, but costs of mate ...familiarity have rarely been considered. A possible cost for males is increased risk of losing paternity if familiarity enables females to detect when alternative sires are desirable, evade mate guarding or invest more in infidelity. To test whether this familiarity cost exists, we examined whether extrapair paternity increases with bond length in the socially monogamous blue-footed booby, Sula nebouxii, using microsatellite-based analysis of 384 broods. Extrapair paternity increased from 9.4% of broods in first pairings to 21.6% in second pairings, then declined to 7.5% in third through eighth pairings. On their first remating with a female, males faced enhanced risk of losing paternity, but thereafter the risk was no greater than on first matings. However, after loss of paternity, males were no more likely to divorce. Effects of familiarity on extrapair paternity could influence the evolution and taxonomic distribution of remating and prolonged pair bonding in socially monogamous animals.
•Animals in long-term partnerships often reap the benefits of increased familiarity.•We show that familiarity between partners can also entail an unsuspected cost.•For male boobies, risk of fathering offspring of a rival male nearly doubled on their first remating with a female.•Thereafter, however, the risk was no greater than on first pairings.•Mate familiarity might enable females to detect when infidelity is more profitable.
Protected urban green spaces (PUGS) are exposed to numerous disturbances and threats since they are immersed in highly dynamic socio-ecological systems. PUGS in highly urbanized cities require ...particular conservation strategies. Here, we propose an approach for PUGS management which integrates three components: i) scientific knowledge (monitoring/restoration), ii) community interaction with the environment, and iii) management decision. Our hypothesis asserts that the intersection of these components should produce a solid management program, provided that the obtained multidisciplinary knowledge meets the needs of information required by the community and decision makers. We tested this hypothesis for a small PUGS located within Mexico City at the National Autonomous University of Mexico campus that holds the Ecological Reserve of Pedregal de San Ángel. Through a participatory approach we built a mental model to understand the perceptions of different campus actors (students, academics and administrators), and their social and ecological relationships with this PUGS. Our findings provide insight into the actors’ perceptions and concerns and suggest that the interactions among the three components, although important, are not self-generated and must be constructed. The findings also suggest that one of the management problems is the mismatch between scientific knowledge and conservation programs. It is paramount to include generated knowledge into management and monitoring programs. The complexity of the PUGS requires an active collaboration among actors and monitoring the development of management strategies using the three components while taking the conservation goals into account.
Individual variation in sexual fidelity and extrapair paternity (EPP) is widely attributed to environmental heterogeneity, but the only variables known to be influential are food abundance and ...density of conspecific breeders (potential extrapair partners). Habitat structure is thought to impact EPP but is rarely measured and, when considered, is usually confounded with food abundance and predation pressure. To sidestep these confounds, we tested whether EPP is associated with habitat structure variables and with local conspecific density in a species whose nesting habitat is not used for feeding and lacks predators. In a blue-footed booby, Sula nebouxii, colony, the probability of EPP in a female's nest was highest in parts of the study plot where there were few obstacles to locomotion, and was quadratically related to local density of sexually active males, even though local males did not sire the EP chicks. The probability of a male breeder siring EP (extrapair) chicks elsewhere was quadratically related to local density of sexually active males around his nest. From these patterns we infer that both sexes may foray for EP interactions, that males and females nesting at intermediate density are most likely to be accessed by forayers, and that obstacles in the vicinity of a female's nest constrain access of foraying males. To our knowledge, this is the first demonstration that individual variation in EPP is associated with habitat structure in the absence of confounding variation in food availability, predation pressure or breeder quality, and the first evidence that EPP opportunities of female and male breeders are reduced by high density of conspecific breeders above a particular threshold.
•Habitat structure and local conspecific density affected extrapair paternity (EPP) in blue-footed boobies.•Habitat structure was not confounded with food availability or predation pressure.•EPP increased when fewer trees and rocks were around the nest.•EPP was greatest at intermediate conspecific density.•Although conspecific density favoured EPP, males sired chicks at distant nests.
Females sometimes obtain older sires for their offspring through extra-pair interactions, but how female age influences paternity is largely unexplored and interactive effects across the age span of ...both sexes have not been analyzed. To test whether female choice of sire age varies with female age in the blue-footed booby (Sula nebouxii), we examined associations between ages of both partners and the probability of extra-pair paternity (EPP) in 350 broods of parents up to 22 years old in a single breeding season. Extra-pair paternity enables a female to select an alternative sire for her offspring and could function to avoid or achieve particular combinations of parental ages. A male age × female age interaction revealed that in young females (≤4 years), EPP decreased with increasing age of the social partner, whereas in old females (≥8 years), it increased. Moreover, sires of extra-pair (EP) chicks of young females paired to young males were on average 6.33 years older than the females’ social partners. Since female boobies control copulatory access, this pattern could imply that young females choose old sires for their proven genetic quality and that old females avoid very old males because matings with them may risk infertility or genetic defects in offspring. Taking female age into account and observing across the whole age span may be necessary for understanding female age-based mate choice.
Los Hongos Formadores de Micorrizas Arbusculares (HFMA) incrementan la supervivencia y producción de biomasa de las plantas hospedadoras y mejoran la absorción de nutrientes. Los HFMA son muy ...importantes en la restauración de suelos degradados y en facilitar el crecimiento de la vegetación bajo condiciones de vivero y campo. Con el fin de restaurar las poblaciones de Kageneckia lanceolata, especie considerada vulnerable por World Conservation Monitoring Center, en este trabajo se propuso evaluar el efecto de la inoculación con HFMA en el crecimiento, la colonización radical y el contenido nutricional de esta especie. Para poner a prueba la hipótesis de que la inoculación con los HFMA promueve el crecimiento y la nutrición de K. lanceolata, se realizó un experimento de invernadero. El inóculo utilizado fue suelo natural proveniente de la rizosfera de un bosque con K. lanceolata. Después de 6 meses, los plantines inoculados con HFMA presentaron dos veces más de biomasa aérea y tres veces más de fósforo que los no inoculados. Este es el primer estudio que muestra el efecto positivo de los HFMA sobre el crecimiento y la nutrición mineral de K. lanceolata.
PDF
