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Anthropogenic changes to the environment challenge animal populations to adapt to new conditions and unique threats. While the study of adaptation has focused on genetic variation, epigenetic mechanisms may also be important. DNA methylation is sensitive to environmental stressors, such as parasites and pesticides, which may affect gene expression and phenotype. We studied the effects of an invasive ec toparasite, Philornis downsi, on DNA methylation of Galápagos mockingbirds (Mimus parvulus). We used the insecticide permethrin to manipulate P. downsi presence in nests of free-living mockingbirds and tested for effects of parasitism on nestling mockingbirds using epiGBS, a reduced-representation bisulfite sequencing (RRBS) approach. To distinguish the confounding effects of insecticide exposure, we con ducted a matching experiment exposing captive nestling zebra finches (Taeniopygia guttata) to permethrin. We used zebra finches because they were the closest model organism to mockingbirds that we could breed in controlled conditions. We identi fied a limited number of differentially methylated cytosines (DMCs) in parasitized versus nonparasitized mockingbirds, but the number was not more than expected by chance. In contrast, we saw clear effects of permethrin on methylation in captive zebra finches. DMCs in zebra finches paralleled documented effects of permethrin exposure on vertebrate cellular signaling and endocrine function. Our results from captive birds indicate a role for epigenetic processes in mediating sublethal nontar get effects of pyrethroid exposure in vertebrates. Environmental conditions in the field were more variable than the laboratory, which may have made effects of both parasitism and permethrin harder to detect in mockingbirds. RRBS approaches such as epiGBS may be a cost-effective way to characterize genome-wide methylation profiles. However, our results indicate that ecological epigenetic studies in natural populations should consider the number of cytosines interrogated and the depth of sequencing in order to have adequate power to detect small and variable effects

The capacity to respond to environmental challenges ultimately relies on phenotypic variation which manifests from complex interactions of genetic and nongenetic mechanisms through development. While we know something about genetic variation and structure of many species of conservation importance, we know very little about the nongenetic contributions to variation. Rhizophora mangle is a foundation species that occurs in coastal estuarine habitats throughout the neotropics where it provides critical ecosystem functions and is potentially threatened by anthropogenic environmental changes. Several studies have documented landscape-level patterns of genetic variation in this species, but we know virtually nothing about the inheritance of nongenetic variation. To assess one type of nongenetic variation, we examined the patterns of DNA sequence and DNA methylation in maternal plants and offspring from natural populations of R. mangle from the Gulf Coast of Florida. We used a reduced representation bisulfite sequencing approach (epi-genotyping by sequencing; epiGBS) to address the following questions: (a) What are the levels of genetic and epigenetic diversity in natural populations of R. mangle? (b) How are genetic and epigenetic variation structured within and among populations? (c) How faithfully is epigenetic variation inherited? We found low genetic diversity but high epigenetic diversity from natural populations of maternal plants in the field. In addition, a large portion (up to ~25%) of epigenetic differences among offspring grown in common garden was explained by maternal family. Therefore, epigenetic variation could be an important source of response to challenging environments in the genetically depauperate populations of this foundation species.

Anthropogenic activities have increased exposure to heavy metal pollution in previously uncontaminated ecosystems, threatening plant communities. Considering that phenotypic variation underlies rapid adjustment to challenging environmental conditions in natural populations, the study of variation in traits related to plant response to heavy metal stress provides valuable insight into the likelihood of a population’s survival. This paper investigates patterns of intraspecific phenotypic variation for heavy metal accumulation and tolerance in bryophytes, one of the most resilient and relatively understudied plant taxa. We examined two moss species with contrasting affinities for heavy metals: the heavy metal specialist Scopelophila cataractae, and the facultative metallophyte Ceratodon purpureus. We sampled four populations of S. cataractae in close microhabitats with different contamination levels of Cd and Cu, one population of C. purpureus in an urban area, and separate lab-maintained male and female isolates from one population of C. purpureus growing in axenic conditions. After clonally propagating all populations under control, Cd and Cu treatments, we measured plant fitness, oxidative damage, and Cd and Cu accumulation. Scopelophila cataractae isolates from microhabitats with higher levels of metals in the field (Sc2, Sc3) were more tolerant than those collected in less contaminated microhabitats (Sc1, Sc4). Sc2 and Sc3 accumulated significantly less Cu in the leaves compared to the stem which could limit damage to their main photosynthetic organs and contribute to the observed differences in Cu tolerance. In contrast C. purpureus showed intraspecific differences in tolerance to Cd and Cu, but not in accumulation. These differences arose among isolates that had never been exposed to heavy metals before. We also report the first evidence for sexual dimorphism for Cd tolerance in this species, with females being more tolerant than males. Altogether, our results provide novel insights into the mechanisms used by bryophytes to deal with heavy metal stress, as well as the first evidence for metal-dependent, sex-specific differences in heavy metal tolerance in bryophytes.

In this study, we used amplified fragment length polymorphism analysis to investigate the genetic structure of the terrestrial moss Pseudoscleropodium purum (Hedw.) M. Fleish. naturally exposed to different levels of atmospheric deposition of heavy metals. We also determined the heavy metal concentrations in samples of this moss to evaluate whether there was a relationship between atmospheric pollution and population genetic diversity. A low level of genetic diversity and a limited gene flow among populations were observed which is in accordance to the prevalence of asexual reproduction in this species. In addition, no significant correlation was found between metal content and gene diversity in P. purum, probably because of the common history of the sampled populations and/or to the lack of a drastic reduction of the size of the population; nonetheless, a clear genetic structure was evident in relation to the existing pollution gradient. Thus, based on the results of the principal coordinate analysis and Bayesian analysis of the genotypes, the mixed structure of the second most polluted population would suggest an ongoing differentiation of metal-tolerant genotypes in the most polluted sites of the sampling area.

Protein expression was assessed in samples of Pseudoscleropodium purum cross-transplanted between one unpolluted (UNP) and two polluted (POLL) sites. Firstly, the level of expression (LE) of 17 proteins differed between native mosses from both types of sites, but differences were only maintained throughout the experiment for 5 of them. The LE of these five proteins changed over time in mosses transplanted from UNP to POLL and vice versa, becoming similar to that in autotransplants. However, these changes occurred slower than changes in the heavy metal concentrations measured in the same samples, and therefore they were not related to atmospheric pollution. Although the proteins identified were associated with moss metabolism, the expected growth reduction in samples autotransplanted within POLL (as a result of the down-regulation of photosynthesis-related proteins), did not occur. This supports the hypothesis that mosses growing in polluted areas adapt to heavy metal pollution and are able to reduce/overcome their toxic effects (i.e., reduced growth). Nevertheless, further specific research must be carried out to identify the proteins involved in this type of response, as lack of information on the bryophyte genome precludes us from reaching further conclusions.

We measured the concentrations of Cd, Cu, Hg, Pb and Zn in samples of the terrestrial moss Pseudoscleropodium purum reciprocally transplanted between an unpolluted and two polluted sampling sites. At the beginning of the experiment, the concentrations of all these elements differed significantly between mosses from the unpolluted site and mosses from the polluted sites. In general, the concentrations of the heavy metals in mosses from both polluted sites transplanted to the unpolluted site decreased until they reached the same levels as in autotransplants at this site (after 480-840 days). However, the concentrations of all heavy metals in mosses transplanted from the unpolluted site to both polluted sites increased to higher levels than in the autotransplants (except for Cu, Hg and Pb at one of the sampling sites). These results led us to conclude that mosses that have been continuously exposed to high atmospheric deposition of heavy metals undergo an adaptive response (probably genotypic) to such conditions. We therefore recommend active rather than passive biomonitoring of air quality in industrial environments because atmospheric deposition could be underestimated, and also recommend further investigation into the mechanisms involved in this response.

Pulsed-field gel electrophoretic analysis of 2,144 methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from patients in Spanish hospitals over a 7-year period revealed 17 predominant profiles. Typing showed the replacement of Iberian clone E1 (ST247-MRSA-I) by two prevalent clones, E7 and E8, that are closely related to each other and have the same genetic background as ST125-MRSA-IV.

In recent years, methicillin-resistant Staphylococcus aureus (MRSA) isolates in Spain have increased dramatically; in 1986 there were only 1.2% MRSA amongst all nosocomial Staphylococcus aureus (SA) isolates, by 1989 this percentage had risen to 44% in some hospital causing a very serious epidemic situation in the country. We have characterized these isolates by direct, reverse and Fisk phage typing and we have also looked for an additional local set of phages to help us to differentiate these strains. We have been able to differentiate an epidemic strain from other MRSA strains which cause sporadic hospital outbreaks, and we have also distinguished between some variants of the epidemic strain. This research has been supported by a grant from the Fondo de Investigaciones Sanitarias de la Seguridad Social (FISS), Ministerio de Sanidad y Consumo, Spain; No. 93/0144. Sí