Marcelo A. Aizen

Marcelo A. Aizen
National University of Comahue | UNCo · Centro Regional Universitario Bariloche

Ph.D.

About

223
Publications
180,538
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Introduction
Dr. Marcelo Aizen graduated in biology at the Universidad de Buenos Aires in 1985 and obtained his PhD at the University of Massachusetts in 1992. At present he is “Investigador Superior” of CONICET (the National Research Council of Argentina) and "Profesor Titular" at the ecology department of the Universidad Nacional del Comahue in Bariloche. His research has been focused on a diversity of basic and applied topics in plant reproductive ecology and plant-pollinator interactions, from the study of pollen tube-pistil interactions to global assessment of pollinator declines and the so-called pollination crisis. In the last years, he and his group have been studiedthe consequences of the invasion of the Buff-tailed bumblebee (Bombus terrestris) on the native biota of Patagonia.
Additional affiliations
January 1995 - present
National University of Comahue
Position
  • Professor
September 1992 - present
National Scientific and Technical Research Council
Position
  • Senior Researcher
Education
September 1982 - August 1992
March 1980 - December 1985
Universidad de Buenos Aires
Field of study
  • Biology

Publications

Publications (223)
Article
Full-text available
Plant–plant interactions can promote diversification in harsh environments through (1) natural selection producing divergent adaptations to extreme and varying abiotic conditions in plants that grow in the open, or (2) genetic drift involving little niche differentiation in plants that grow associated with others. We assessed whether alpine plant g...
Article
Full-text available
Aim Local effects of ecosystem engineers on biodiversity can scale up to the landscape level, stressing the importance of ecological processes as determinants of species richness at larger spatial scales. In harsh environments, cushion plants often act as ecosystem engineers given their ability to buffer extreme abiotic conditions, thus providing u...
Chapter
Increasing honey demand and global coverage of pollinator-dependent crops within the context of global pollinator declines have accelerated international trade in managed bees. Bee introductions into agricultural landscapes outside their native ranges have triggered noteworthy invasions, especially of the African honey bee in the Americas and the E...
Article
Full-text available
Artificial selection and genetic engineering plus an expanding repertoire and use of agrochemical inputs have allowed a rapid and continuous increase in crop yield (i.e., volume production per unit area) over the last century, which is needed to fulfill food demands from a growing human population. However, the first signs of yield deceleration and...
Article
Wild and managed bees are key pollinators, ensuring or enhancing the reproduction of a large fraction of the world's wild flowering plants and the yield of ∼85% of all cultivated crops. Recent reports of wild bee decline and its potential consequences are thus worrisome. However, evidence is mostly based on local or regional studies; the global sta...
Article
Full-text available
Aim Aggregated species occurrence data are increasingly accessible through public databases for the analysis of temporal trends in the geographic distributions of species. However, biases in these data present challenges for statistical inference. We assessed potential biases in data available through GBIF on the occurrences of four flower‐visiting...
Article
Full-text available
ABSTRACT. Mounting evidence shows that pollinators are declining as a result of widespread environmental degradation. This loss raises concerns that a global pollination crisis could threaten the human food supply by decreasing crop yield and even promote famine under a hypothetical scenario of total pollinator extinction. This catastrophic possibi...
Article
Modern agriculture is becoming increasingly pollinator-dependent. However, the global stock of domesticated honeybees is growing at a slower rate than its demand, while wild bees are declining worldwide. This uneven scenario of high pollinator demand and low pollinator availability can translate into increasing pollination limitation, reducing the...
Article
Full-text available
Introduction Cold-adapted bumblebees are vulnerable to climate change (CC). South American Bombus dahlbomii, the southernmost bumblebee worldwide, has strongly declined since the 1990s and may be particularly susceptible to current and future CC. Aims/methods We asked (1) whether current CC had a role in the observed decline of this species and (2...
Article
Full-text available
Nectar robbers are common cheaters of plant-pollinator mutualisms by making holes in flower tissues to attain floral rewards often without providing pollination service. Most studies have focused on the consequences of nectar robbing on plant reproduction, whereas the underlying drivers of spatiotemporal variation in nectar robbing have been compar...
Article
Full-text available
Aim: Plant reliance on animal mutualists is expected to decrease with latitude owing to increasing environmental instability. As a consequence, more erratic animal pollination in the temperate zones than in the tropics could translate into lower efficiency in pollen transfer, and thus increasing pollen wastage. Despite the relevance of this hypothe...
Preprint
Full-text available
Aim: Aggregated species occurrence data are increasingly accessible through public databases for the analysis of temporal trends in species’ distributions. However, biases in these data present challenges for robust statistical inference. We assessed potential biases in data available through GBIF on the occurrences of four flower-visiting taxa: be...
Article
Full-text available
While feeding, foragers can alter their environment. Such alteration constitutes ecological niche construction (ENC) if it enables future benefits for the constructor and conspecific individuals. The environmental modification may also affect non‐constructing, bystander species, especially if they share resources with constructor species. If so, EN...
Article
Full-text available
Pollinator-mediated plant–plant interactions have traditionally been viewed within the competition paradigm. However, facilitation via pollinator sharing might be the rule rather than the exception in harsh environments. Moreover, plant diversity could be playing a key role in fostering pollinatormediated facilitation. Yet, the facilitative efect o...
Article
One of the most important challenges facing global agriculture is to ensure an adequate, stable food supply while conserving soil, water and biodiversity. The yield stability of pollinator-dependent crops, such as pear and apple, can be negatively affected by variability of the pollination service, which in turn can reduce mean yield. We explored h...
Article
An analysis of plant–pollinator interactions reveals that the presence of abundant plant species favours the pollination of rare species. Such asymmetric facilitation might promote the coexistence of species in diverse plant communities. Abundant plant species boost the pollination of rare plant species.
Article
Full-text available
Insect pollinators have been relocated by humans for millennia and are, thus, among the world’s earliest intentional exotic introductions. The introduction of managed bees for crop pollination services remains, to this day, a common and growing practice worldwide and the number of different bee species that are used commercially is increasing. Bein...
Article
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Invasive species can reach high abundances and dominate native environments. One of the most impressive examples of ecological invasions is the spread of the African sub‐species of the honey bee throughout the Americas, starting from its introduction in a single locality in Brazil. The invasive honey bee is expected to more negatively impact bee co...
Article
Cultivation of pollinator-dependent crops has expanded globally, increasing our reliance on insect pollination. This essential ecosystem service is provided by a wide range of managed and wild pollinators whose abundance and diversity are thought to be in decline, threatening sustainable food production. The Western honey bee (Apis mellifera) is am...
Article
Ecosystems are interconnected and complex, but conservation has often focused on rehabilitating individual species. A systems-ecology approach aims to support overall ecosystem structure and maintain ecological functions, and may be especially pertinent for mutualistic plant-pollinator communities. This approach focuses on species interactions as t...
Article
Greater susceptibility to herbivory can arise as an effect of crop domestication. One proposed explanation is that defenses decreased intentionally or unintentionally during the domestication process, but evidence remains elusive. An alternative but non‐excluding explanation is presumed selection for higher nutritional quality. ●We used a meta‐anal...
Article
1. Domestication generally involves two sequential processes: initial identification of wild species with desirable characteristics (“progenitor filtering”); and subsequent artificial and natural selection that respectively improve features preferred by humans and adapt species to cultivation/captivity (“domestication selection”). Consequently, dom...
Article
Large-scale changes introduced by industrial agriculture can affect other productive activities such as beekeeping, which heavily depends on floral resources and responsible management of agrochemicals. To assess the long-term effect of soybean expansion on honey production in Argentina, we evaluated the relationships between the area cultivated wi...
Chapter
Full-text available
This book contains 23 chapters divided into seven parts. Part I reviews the key hypotheses in invasion ecology that invoke biotic interactions to explain aspects of plant invasion dynamics; and reviews models, theories and hypotheses on how invasion performance and impact of introduced species in recipient ecosystems can be conjectured according to...
Chapter
Multiple anthropogenic challenges threaten nature’s contributions to human well-being. Agricultural expansion and conventional intensification are degrading biodiversity and ecosystem functions, thereby undermining the natural foundations on which agriculture is itself built. Averting the worst effects of global environmental change and assuring ec...
Preprint
Full-text available
Pollinator decline has attracted global attention, and substantial efforts are underway to respond, through national pollinator strategies and action plans. These policy responses require clarity on what is driving pollinator decline, and what risks it generates for society, in different parts of the world. Using a formal expert elicitation process...
Article
Wild and managed bees are key pollinators, providing ecosystem services to a large fraction of the world’s flowering plants, including ~85% of all cultivated crops. Recent reports of wild bee decline and its potential consequences are thus worrisome. However, evidence is mostly based on local or regional studies; global status of bee decline has no...
Article
Full-text available
Wild pollinators are declining and the number of managed honey bee colonies is growing slower than agricultural demands for pollination. Because of these contrasting trends in pollinator demand and availability, breeding programs for many pollinator-dependent crops have focused on reducing the need for pollinators. Although numerous crop varieties...
Article
1.Despite the crucial importance of biotic pollination for many crops, land managers rarely monitor the levels of crop pollination to guide farming decisions. 2.The few existing pollination recommendations focus on a particular number of honey‐bee or bumble‐bee hives per crop area, but these guidelines do not accurately predict the actual pollinati...
Article
The alarming loss of pollinator diversity world‐wide can reduce the productivity of pollinator‐dependent crops, which could have economic impacts. However, it is unclear to what extent the loss of a key native pollinator species affects crop production and farmer's profits. By experimentally manipulating the presence of colonies of a native bumbleb...
Chapter
Full-text available
This book contains 23 chapters divided into seven parts. Part I reviews the key hypotheses in invasion ecology that invoke biotic interactions to explain aspects of plant invasion dynamics; and reviews models, theories and hypotheses on how invasion performance and impact of introduced species in recipient ecosystems can be conjectured according to...
Preprint
Full-text available
Wild and managed bees are key pollinators, providing ecosystem services to a large fraction of the world’s flowering plants, including ~85% of all cultivated crops. Recent reports of wild bee decline and its potential consequences are thus worrisome. However, evidence is mostly based on local or regional studies; global status of bee decline has no...
Article
Full-text available
Human land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield–related ecosystem services can be maintained by a few dominant species or rely on high richness remains unclear. Using a global database from 89 studies (with 1475 locations), we partition the relative importance...
Article
Full-text available
Human land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield–related ecosystem services can be maintained by a few dominant species or rely on high richness remains unclear. Using a global database from 89 studies (with 1475 locations), we partition the relative importance...
Article
Full-text available
Mosses are a dominant ground cover in a wide array of ecosystems, especially in those developing under cold-stressed environments such as arctic and alpine ice-melting glacial forelands. Consequently, mosses may influence the performance and distribution of other plants. Here, we assessed the nature of interactions between vascular plants and cushi...
Article
Full-text available
The global increase in the proportion of land cultivated with pollinator‐dependent crops implies increased reliance on pollination services. Yet agricultural practices themselves can profoundly affect pollinator supply and pollination. Extensive monocultures are associated with a limited pollinator supply and reduced pollination, whereas agricultur...
Article
Preserving species diversity is critical to ensure ecosystem functioning; however, different components of diversity might respond to human disturbance in different ways. Similarly, trophic levels might have uncoupled responses to the same disturbance, thus ameliorating or aggravating the persistence of ecological communities. In this study, we ana...
Article
Full-text available
Ecological interaction and adaptation both depend on phenotypic characteristics. In contrast to the common conception of the “adult” phenotype, plant bodies develop continuously during their lives. Furthermore, the different units (metamers) that comprise plant bodies are not identical copies, but vary extensively within individuals. These characte...
Article
The area cultivated with pollinator-dependent crops is increasing worldwide, while a shortfall in pollinator availability is a growing problem in many agroecosystems. For this reason, many highly pollinator-dependent crops are nowadays pollinated artificially by humans. Here, we compared the efficiency of artificial and bee pollination practices on...
Preprint
Full-text available
Human land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield-related ecosystem services can be maintained by few abundant species or rely on high richness remains unclear. Using a global database from 89 crop systems, we partition the relative importance of abundance and s...
Article
• Background and Aims In animal-pollinated plants, direct and indirect selection for large and small flowers in predominantly outcrossing and selfing species, respectively, is a common consequence of pollen limitation (PL). However, many hermaphroditic species show a mixed-mating system known as delayed selfing, which provides reproductive assuranc...
Article
Full-text available
Premise of research. Sexual functions in gymnosperms are mostly performed by separate reproductive structures, which largely reduces sexual interference and sets the scene for morphological and functional sexual specialization. The evolutionary trajectories followed by traits related to the male and female functions are therefore expected to be unc...
Article
Full-text available
Pollen limitation can strongly influence reproduction of pollinator-dependent plants. Flower abundance can affect pollination ‘quantity’ and ‘quality’ due to its influence on pollen availability and foraging patterns of pollinators, ultimately impacting on seed production. We complemented individual-based measurements with landscape-level metrics t...
Article
Full-text available
Important groups of mutualistic species are threatened worldwide, and identifying factors that make them more or less fragile in the face of disturbance is becoming increasingly critical. Although much research has focused on identifying the ecological factors that favor the stability of communities rich in mutualists, much less has been devoted to...
Poster
La introducción en 1996 del paquete tecnológico que incluye soja genéticamente modificada y Glifosato produjo en la Argentina un avance sostenido de la soja sobre otros cultivos. Este proceso favoreció el avance de la frontera agrícola sobre áreas naturales en un 74% y una pérdida de la diversidad de cultivos. En simultáneo se ha observado una dism...
Article
Full-text available
Background A classical dichotomous perspective proposes that either pollination or plant resources limit seed production. However, ovule number could also be limiting when pollination results in complete ovule fertilization and there are more plant resources available than needed to develop seeds. Moreover, this dichotomous view assumes that all fl...
Article
The honey bee (Apis mellifera L.) has been spread all over the world by humans and is now the most widespread bee invasive species. In spite of being considered a beneficial species, there is a controversy around its impact on natural habitats caused by its high densities. Here we review the most important effects and mechanisms attributed to an in...
Article
Full-text available
Globally, agriculture increasingly depends on pollinators to produce many seed and fruit crops. However, what constitutes optimal pollination service for pollinator-dependent crops remains unanswered. We developed a simulation model to identify the optimal pollination service that maximizes fruit quality in crops. The model depicts the pollination...
Article
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1. The global trade of species promotes diverse human activities but also facilitates the introduction of potentially invasive species into new environments. As species ignore national boundaries, unilateral national decisions concerning species trade set the stage for transnational species invasion with significant conservation, economic and polit...
Article
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The exponential growth of the human population often causes the overexploitation of resources and disruption of ecological interactions. Here, we propose that the antagonist effect of humans on exploited species might be alleviated with the advent of a second predator species. We focused on the complex interactions between an endangered conifer (Ar...
Data
Proportion of partially eaten seeds between people's bags and those collected underneath trees;Intact seed density comparison;Influence of seed size and weight on the germination results;Proportion of germinated seeds in relation to days passed after sowing
Article
Full-text available
Invasive alien species modify pollinator biodiversity and the services they provide that underpin ecosystem function and human well-being. Building on the Intergovernmental Science-Policy Platform for Biodiversity and Ecosystem Services (IPBES) global assessment of pollinators and pollination, we synthesize current understanding of invasive alien i...
Article
Despite global interest in the role of pollinators for food production, their impact on farmers’ profit, which determines farmers’ livelihood and land-use decisions, is unclear. Although average values of pollinator benefits are generally assumed, there is potential for large spatial variation among crop species and varieties or among pollinator ma...
Article
Full-text available
La biodiversidad está siendo destruida a una tasa alarmante. Una de las principales causas de esta pérdida es el cambio de uso del suelo, que se basa en la agricultura y la ganadería convencionales. Las prácticas de manejo como el monocultivo y el uso intensivo de agroquímicos reducen el número de especies de plantas, aves, insectos y otros grupos...
Article
Full-text available
Pollinators are important agents of selection on floral traits, including nectar sugar composition. Although it is widely assumed that the proportion of sugars (mainly sucrose, glucose and fructose) in nectar reflects pollinators’ physiological limitations and digestive efficiency, the relative impact of pollinators and abiotic factors on nectar su...
Article
Full-text available
Conservation biology can profit greatly from incorporating a phylogenetic perspective into analyses of patterns and drivers of species extinction risk. We applied such an approach to analyse patterns of bumblebee (Bombus) decline. We assembled a database representing approximately 43% of the circa 260 globally known species, which included species...
Article
Effective pollination is a complex phenomenon determined by both species-level and community-level factors. While pollinator communities are constituted by interacting organisms in a shared environment, these factors are often simplified or overlooked when quantifying species-level pollinator effectiveness alone. Here, we review the recent literatu...
Chapter
Full-text available
Plant–pollinator interactions and associated pollination services are essential for crop production and the integrity of terrestrial ecosystem services. Introduced pollinators, in particular social bees such as honeybees and bumblebees, have become invaders in many regions of the world, strongly affecting the pollination of native, cultivated, and...
Article
Full-text available
The PREDICTS project—Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)—has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used t...