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This paper develops a spatial rural economy model of adaptation to climate change that accounts for a multitude of rural enterprises across a diversity of ecosystems in South America using household surveys. We model adoptions of crops, livestock, and forests. Both specialized and diversified enterprises are modelled. This paper finds that livestock, forests, and a diversification into crops, livestock, and forests are key adaptation strategies. Under the UKMO (United Kingdom Meteorological Office) scenario, a livestock-only enterprise would expand by 4 per cent, a crops-livestock-forests by 3 per cent, and a forests-only by 3 per cent. Adaptation behaviours are closely tied with ecosystem changes under global warming. A livestock-only would increase especially in the grasslands. A crops-livestock-forests enterprise expands into xeromorphic forests. A crops-livestock expands in Andean grasslands and tall grasslands. A forests-only expands in the coasts and woody zones. A crops-only enterprise decreases across South America. Resumen Utilizando encuestas a hogares, en este artículo se desarrolla un modelo espacial de economía rural para la adaptación al cambio climático, con la capacidad de representar una gran cantidad de empresas rurales dentro de una diversidad de ecosistemas en América del Sur. Se modeliza la adopción de cultivos, ganado y bosques. Se modelizan tanto empresas especializadas como diversificadas. El artículo encontró que el ganado, los bosques, y una diversificación en cuanto a cultivos, ganado y bosques son estrategias claves de adaptación. Bajo un escenario propuesto por la Oficina Meteorológica del Reino Unido (UKMO, siglas en inglés), una explotación dedicada solamente a la ganadería aumentaría en un 4 por ciento, una dedicada a cultivos-ganadería-bosques un 3 por ciento, y una dedicada exclusivamente a bosques un 3 por ciento. Los comportamientos para la adaptación están estrechamente ligados a cambios en los ecosistemas debidos al calentamiento global. Una explotación exclusivamente ganadera aumentaría especialmente en el ecosistema de pastizal. Una explotación de cultivos-ganadería-bosques podría expandir en bosques xeromórficos. Una explotación basada en cultivos-ganado expandiría en áreas de pastizales Andinos y pastizal alto. Las explotaciones basadas solamente en bosque expandirían en las costas y zonas boscosas. Una explotación exclusivamente de cultivos disminuiría en América del Sur. [ABSTRACT FROM AUTHOR]

The South American Cerrado is the largest tropical savanna of the world, and one of the most threatened biomes on the Earth. Levels of bird endemism in this biome are controversial, but the most up-to-date study points to 30 endemic species. In this paper, I analysed the recent range shift by one of those species, the curl-crested jay Cyanocorax cristatellus, comparing it with three other alleged Cerrado endemics (lesser nothura Nothura minor, chestnut-capped foliage-gleaner Hylocryptus rectirostris, and grey-backed tachuri Polystictus superciliaris) and a ‘near-endemic’ (white-banded tanager Neothraupis fasciata). The curl-crested jay expanded its range considerably into south-eastern Brazil during the last century, colonizing extensive areas formerly covered by the Atlantic forest, which has been almost completely cleared by human activity. I found no evidence of recent range shift for the four other species studied, but demonstrated that the grey-backed tachuri is not a Cerrado endemic. I found that the vegetation map used by previous authors to classify birds as endemics is imprecise and out-of-date, not depicting well the biome limits, resulting in an arbitrary, sometimes erroneous, classification. I suggested the adoption of a more modern and detailed Cerrado map. The necessity of a comprehensive review in the list of Cerrado's endemic birds in light of modern vegetation maps is highlighted. [ABSTRACT FROM AUTHOR]

Global biodiversity is organised into biogeographic regions that comprise distinct biotas. The contemporary factors maintaining differences in species composition between regions are poorly understood. Given evidence that populations with sufficient genetic variation can adapt to fill new habitats, it is surprising that more homogenisation of species assemblages across regions has not occurred. Theory suggests that expansion across biogeographic regions could be limited by reduced adaptive capacity due to demographic variation along environmental gradients, but this possibility has not been empirically explored. Using three independently curated data sets describing continental patterns of mammalian demography and population genetics, we show that populations near biogeographic boundaries have lower effective population sizes and genetic diversity, and are more genetically differentiated. These patterns are consistent with reduced adaptive capacity in areas where one biogeographic region transitions into the next. That these patterns are replicated across mammals suggests they are stable and generalisable in their contribution to long‐term limits on biodiversity homogenisation. Understanding the contemporary processes that maintain compositional differences among regional biotas is crucial for our understanding of the current and future organisation of global biodiversity. [ABSTRACT FROM AUTHOR]

Plant defense suppression is an offensive strategy of herbivores, in which they manipulate plant physiological processes to increase their performance. Paradoxically, defense suppression does not always benefit the defense‐suppressing herbivores, because lowered plant defenses can also enhance the performance of competing herbivores and can expose herbivores to increased predation. Suppression of plant defense may therefore entail considerable ecological costs depending on the presence of competitors and natural enemies in a community. Hence, we hypothesize that the optimal magnitude of suppression differs among locations. To investigate this, we studied defense suppression across populations of Tetranychus evansi spider mites, a herbivore from South America that is an invasive pest of solanaceous plants including cultivated tomato, Solanum lycopersicum, in other parts of the world. We measured the level of expression of defense marker genes in tomato plants after infestation with mites from eleven different T. evansi populations. These populations were chosen across a range of native (South American) and non‐native (other continents) environments and from different host plant species. We found significant variation at three out of four defense marker genes, demonstrating that T. evansi populations suppress jasmonic acid‐ and salicylic acid‐dependent plant signaling pathways to varying degrees. While we found no indication that this variation in defense suppression was explained by differences in host plant species, invasive populations tended to suppress plant defense to a smaller extent than native populations. This may reflect either the genetic lineage of T. evansi—as all invasive populations we studied belong to one linage and both native populations to another—or the absence of specialized natural enemies in invasive T. evansi populations. [ABSTRACT FROM AUTHOR]

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For decades, palynologists working in tropical South America are using the genus Podocarpus as a climate indicator although without referring to any modern data concerning its distribution and limiting factors. With the aim to characterize the modern and past distribution of the southern conifer Podocarpus in Brazil and to obtain new information on the distribution of the Atlantic rainforest during the Quaternary, we examined herbarium data to locate the populations of three Brazilian endemic Podocarpus species: P. sellowii, P. lambertii, and P. brasiliensis, and extracted DNA from fresh leaves from 26 populations. Our conclusions are drawn in the light of the combination of these three disciplines: botany, palynology, and genetics. We find that the modern distribution of endemic Podocarpus populations shows that they are widely dispersed in eastern Brazil, from north to south and reveals that the expansion of Podocarpus recorded in single Amazonian pollen records may have come from either western or eastern populations. Genetic analysis enabled us to delimit regional expansion: between 5° and 15° S grouping northern and central populations of P. sellowii expanded c. 16,000 years ago; between 15° and 23° S populations of either P. lambertii or sellowii expanded at different times since at least the last glaciation; and between 23° and 30° S, P. lambertii appeared during the recent expansion of the Araucaria forest. The combination of botany, pollen, and molecular analysis proved to be a rapid tool for inferring distribution borders for sparse populations and their regional evolution within tropical ecosystems. Today the refugia of rainforest communities we identified are crucial hotspots to allow the Atlantic forest to survive under unfavourable climatic conditions and, as such, offer the only possible opportunity for this type of forest to expand in the event of a future climate change. [ABSTRACT FROM AUTHOR]

Predator assemblages are complex systems in which asynchrony in the dynamics of resources and consumers, and the idiosyncratic perception of environmental conditions by the predators may obscure the detection of expected patterns. We disentangle the specific effects of these variables on the guild structure of a vertebrate predatory assemblage in a semiarid ecosystem of western South America. Over 16 years, this system faced dramatic fluctuations in prey availability associated with four El Niño events. After controlling for other sources of variation, we tested if increased resource availability is associated with higher niche overlaps, as expected from the lean/fat scenario. We determined the existence of two trophic guilds of predators (specialized mammal-eaters and omnivorous species with emphasis on arthropods) and found that they responded to increased productivity both at the guild and whole assemblage levels. However, the population response of arthropod prey (almost simultaneous) and of different small mammal prey (delayed by 1 or 2 years) to productivity imposed a degree of asynchrony in prey availability and in the response of predators. This resulted in the between-guilds exchange of predator species depending on mammal prey scarcity or abundance. As a consequence, the observed pattern was an apparent lack of response at the assemblage level. Despite differences in the perception of prey levels by predators, we conclude that each one of them responded accordingly to theoretical predictions following a simple rule: if prey resources are not limiting, predators behave opportunistically converging over the most abundant resources, thus increasing niche overlap; if prey shortages occur, predators specialize on those prey resources that they gather most efficiently, thus lowering niche overlap; if resources become even scarcer, all predators converge again upon the few prey resources still available, thus increasing overlap – out of necessity. [ABSTRACT FROM AUTHOR]

I make a summary review of how El Niño/Southern Oscillation (ENSO) determines peculiar atmospheric and oceanographic conditions in western South America, thus affecting precipitation patterns in adjacent land masses, with cascading effects on marine and terrestrial plants, on sea and land birds, and on marine and terrestrial mammals. With regard to terrestrial ecosystems, I discuss the following biotic responses to El Niño-driven precipitation: 1) aboveground vegetation flushes immediately among herbs but not among shrubs. 2) The seed bank is quickly replenished of ephemeral seeds, but perennial seeds recover one year later. 3) Small rodents irrupt within months of El Niño arrival, but larger ones take a full year to increase. 4) Predator numbers lag one year behind their mammal prey, with smaller predators responding more quickly. Considering these responses, I offer a simplified model of El Niño-driven bottom-up control in terrestrial ecosystems of western South America. Apart from the direct links already described, there is a weak feedback loop between the plant compartments (vegetation and seeds) and their herbivores: primary productivy is the driving force, and is little affected by herbivory. Another weak feedback loop links herbivores and their predators: the latter seem to just “surf” over prey levels, skimming excess prey. [ABSTRACT FROM AUTHOR]

The article discusses the ecological and floristic convergence of some plant formations in South America. The author considers certain traits of flora, vegetation and climate as a first approximation to compare corresponding ecosystems. The comparative analysis may be viewed at three different approaches. The first is the assessment of the degree of environmental similarity under which similar types occur. The second concerns the structural and functional convergence of vegetation. The third approach focuses on a morpho-ecological characterization of each of the communities through their main plant components.