A Study of the Coevolution of Digital Organisms with an Evolutionary Cellular Automaton

This paper presents an Evolutionary Cellular Automaton (ECA) that simulates the evolutionary dynamics of biological interactions by manipulating strategies of dispersion and associations between digital organisms. The parameterization of the different types of interaction and distribution strategies using configuration files generates easily interpretable results. In that respect, ECA is an effective instrument for measuring the effects of relative adaptive advantages and a good resource for studying natural selection. Although ECA works effectively in obtaining the expected results from most well-known biological interactions, some unexpected effects were observed. For example, organisms uniformly distributed in fragmented habitats do not favor eusociality, and mutualism evolved from parasitism simply by varying phenotypic flexibility. Finally, we have verified that natural selection represents a cost for the emergence of sex by destabilizing the stable evolutionary strategy of the 1:1 sex ratio after generating randomly different distributions in each generation.

Forests Without Frugivores and Frugivores Without Forests – An Investigation Into the Causes of a Paradox in One of the Last Archipelagos Colonized by Humans

The Mascarenes are sadly famous worldwide for the massive extinction of their native vertebrates since recent human colonization. However, extinction patterns show astonishing disparities between the two main islands and between lineages of forest vertebrates. On Réunion (2,512 km2, 3,070 m) where about a third of native habitats remains, most large-bodied vertebrates, especially frugivores, collapsed by the first half of the 18th century, while several have survived longer and some still exist on Mauritius (1,865 km2, 828 m) where more than 95% of native habitats have been transformed. Considering lineages of forest vertebrates shared by both islands (23 genera, 53 species), we test the hypothesis that differing patterns of lowland suitable habitat destruction is the main cause behind this paradox. Before that, we assess the potential impact of other major drivers of extinctions since first contact with humans. Firstly, Mauritius shows earlier and more numerous introductions of mammal predators known for their devastating impact (except northern islets which have thus become important sanctuaries for several squamates). Secondly, settlers were inveterate hunters on both islands, but while Réunion was overhunted before Mauritius, the burst of human population in the latter in late 18th century has not led to the rapid extinction of all large native vertebrates. These two factors alone therefore cannot explain the observed paradox. Rather, the early destruction of lowland habitats (<400 m) on Réunion is concomitant with most extinctions of forest vertebrate, notably frugivores that rapidly lost most lowland habitats dominated by large fleshy-fruited plants. Moreover, landform-induced fragmentation has likely decreased the ability of adjacent habitats to act as effective refuges. Conversely, Mauritius retained suitable low-fragmented habitats until the late 19th which probably allowed, at least for a time, several native vertebrates to escape from multiple human-induced disturbances. Despite the almost total destruction of native habitats since then on Mauritius, conservation actions have saved several threatened vertebrate species that play a fundamental role in the functioning of native ecosystems. The fact that there are now more favorable habitats on Réunion than on Mauritius argues for the rewilding of Réunion with these extant large vertebrates.

Successful management of invasive rats across a fragmented landscape

Summary Introduced mammalian predators are responsible for the decline and extinction of many native species, with rats (genus Rattus) being among the most widespread and damaging invaders worldwide. In a naturally fragmented landscape, we demonstrate the multi-year effectiveness of snap traps in the removal of Rattus rattus and Rattus exulans from lava-surrounded forest fragments ranging in size from <0.1 to >10 ha. Relative to other studies, we observed low levels of fragment recolonization. Larger rats were the first to be trapped, with the average size of trapped rats decreasing over time. Rat removal led to distinct shifts in the foraging height and location of mongooses and mice, emphasizing the need to focus control efforts on multiple invasive species at once. Furthermore, because of a specially designed trap casing, we observed low non-target capture rates, suggesting that on Hawai‘i and similar islands lacking native rodents the risk of killing non-target species in snap traps may be lower than the application of rodenticides, which have the potential to contaminate food webs. These efforts demonstrate that targeted snap-trapping is an effective removal method for invasive rats in fragmented habitats and that, where used, monitoring of recolonization should be included as part of a comprehensive biodiversity management strategy.

Pronounced Genetic Separation Among Varieties of thePrimula cusickianaSpecies Complex, a Great Basin Endemic

Distinguishing between unique species and populations with strong genetic structure is a common challenge in population genetics, especially in fragmented habitats where allopatric speciation may be widespread and distinct groups may be morphologically similar. Such is often the case with species complexes across sky island environments. In these scenarios, biogeography may help to explain the relations between species complex members, and RADseq methods are commonly used to compare closely related species across thousands of genetic loci. Here we use RADseq to clarify the relations between geographically distinct but morphologically similar varieties of thePrimula cusickianaspecies complex, and to contextualize past findings of strong genetic structure among populations within varieties. Our genomic analyses demonstrate pronounced separation between isolated populations of this Great Basin endemic, indicating that the current varietal classification of complex members is inaccurate and emphasizing their conservation importance. We discuss how these results correspond to recent biogeographical models used to describe the distribution of other sky island taxa in western North America. Our findings also fit into a wider trend observed for alpinePrimulaspecies complexes, and we consider how heterostylous breeding systems may be contributing to frequent diversification via allopatric speciation in this genus.

Influence of Environmental Factors on the Genetic and Chemical Diversity of Brickellia veronicifolia Populations Growing in Fragmented Shrublands from Mexico

Brickellia veronicifolia is a native Asteraceae from Mexico that persists in fragmented habitats. This investigation reports the genetic and chemical diversity of B. veronicifolia. The diversity analysis based on iPBS markers showed an averaged Shannon index (S) of 0.3493, a Nei genetic diversity (h) of 0.2256, and a percentage of polymorphic loci average (P) of 80.7867%. The population structure obtained by AMOVA revealed that the highest variation found within populations was 94.58%. GC-MS profiling of six populations indicated that major volatiles were β–caryophyllene (11.63%), spathulenol (12.85%), caryophyllene oxide (13.98%), α–cadinol (7.04%), cubedol (6.72%) and tau-muurolol (4.81%). Mantel tests suggested a statistically significant relationship between minor volatiles and geographical distance (r = 0.6163; p = 0.0470; p ˂ 0.05). Likewise, major volatiles showed a significant correlation with the soil pH (r = 0.6862; p = 0.0230) and maximum temperature (r = 0.4999; p = 0.0280). Our study suggests that the variation and genetic divergence of B. veronicifolia has no relationship with climatic parameters, whereas the volatiles are probably influenced by environmental factors and not by the genotype per se. Based on the characteristics of B. veronicifolia, this plant could be considered as a candidate for restoring fragmented shrublands in Mexico.

Dispersal and migration have contrasting effects on butterfly flight morphology and reproduction

Movement may fundamentally alter morphology and reproductive states in insects. In long-distance migrants, reproductive diapause is associated with trade-offs between diverse life-history traits such as flight morphology and lifespan. However, many non-diapausing insects engage in shorter resource-driven dispersals. How diapause and other reproductive states alter flight morphology in migrating versus dispersing insects is poorly understood. To find out, we compared flight morphology in different reproductive states of multiple butterfly species. We found that dispersers consisted of ovulating females with higher egg loads compared with non-dispersing females. This trend was in stark contrast with that of migrating female butterflies in reproductive diapause, which made substantially higher investment in flight tissue compared with reproductively active, non-migrating females. Thus, long-distance migration and shorter resource-driven dispersals had contrasting effects on flight morphology and egg loads. By contrast, male flight morphology was not affected by dispersal, migration or associated reproductive states. Thus, dispersal and migration affected resource allocation in flight and reproductive tissue in a sex-specific manner across relatively mobile versus non-dispersing individuals of different species. These findings suggest that dispersals between fragmented habitats may put extra stress on egg-carrying females by increasing their flight burdens.

Eco-Epidemiological Evidence of the Transmission of Avian and Human Influenza A Viruses in Wild Pigs in Campeche, Mexico

Influenza, a zoonosis caused by various influenza A virus subtypes, affects a wide range of species, including humans. Pig cells express both sialyl-α-2,3-Gal and sialyl-α-2,6-Gal receptors, which make them susceptible to infection by avian and human viruses, respectively. To date, it is not known whether wild pigs in Mexico are affected by influenza virus subtypes, nor whether this would make them a potential risk of influenza transmission to humans. In this work, 61 hogs from two municipalities in Campeche, Mexico, were sampled. Hemagglutination inhibition assays were performed in 61 serum samples, and positive results were found for human H1N1 (11.47%), swine H1N1 (8.19%), and avian H5N2 (1.63%) virus variants. qRT-PCR assays were performed on the nasal swab, tracheal, and lung samples, and 19.67% of all hogs were positive to these assays. An avian H5N2 virus, first reported in 1994, was identified by sequencing. Our results demonstrate that wild pigs are participating in the exposure, transmission, maintenance, and possible diversification of influenza viruses in fragmented habitats, highlighting the synanthropic behavior of this species, which has been poorly studied in Mexico.

Putting the Intellectual Back in Environmental History

At its birth, American environmental history had strong connections with intellectual history. Books such as Roderick Nash's Wilderness and the American Mind and Donald Worster's Nature's Economy made the rise of preservationist and ecological thinking central to the field's early identity. But during the last several decades, as intellectual historians have engaged in their own soul-searching, American environmental historians retreated from engagement with intellectual history in favor of a “cultural turn.” In some ways, this retreat was surprising, because environmental historians became more circumspect about the very approaches that intellectual historians were questioning in their own scholarly practices: whether we could generalize from elite sources, disengage ideas from their social or cultural contexts, separate out a distinct intellectual realm and its exemplary intellects from histories of popular knowledge, or locate such a thing as an “American mind.” The second generation of American environmental historians continued to study environmental ideas, of course, but with less willingness to venerate canonical environmental thinkers and more interest in how American ideas of nature were socially and culturally constructed. As environmental historians became more critical of environmentalist ideas—finding in them signs of class position, racial formation, consumer status, and uncritical borrowings from science—we tended to become suspicious of the realm of ideas in general. Despite these parallels within our fields, the moment compelled environmental historians to turn away from intellectual history. One sad result is that environmental historians do not seem to have stayed abreast of intellectual historiography. Another, if my cursory review of this journal's recent tables of contents is any indication, is that environmental topics seem peripheral to the field of intellectual history. For the sake of both fields, it's time to restore the fragmented habitats that have isolated our subdisciplines.