Gabriela Gleiser - Academia.edu (original) (raw)

Papers by Gabriela Gleiser

ABSTRACTCrop yields,i.e., harvestable production per unit of cropland area, are in decline for a ... more ABSTRACTCrop yields,i.e., harvestable production per unit of cropland area, are in decline for a number of crops and regions, but the drivers of this process are poorly known. Global decreases in pollinator abundance and diversity have been proposed as a major driver of yield declines in crops that depend on animals, mostly bees, to produce fruits and seeds. Alternatively, widespread tree mortality has been directly and indirectly related to global climate change, which could also explain yield decreases in tree crops. As tree crops are expected to be more dependent on pollinators than other crop types, disentangling the relative influence of growth form and pollinator dependence is relevant to identify the ultimate factors driving yield declines. Yield decline, defined here as a negative average annual yearly change in yield from 1961 to 2020, was measured in 4270 time series, involving 136 crops and 163 countries and territories. About one-fourth of all time series showed declines...

bioRxiv (Cold Spring Harbor Laboratory), Apr 29, 2023

Yields are in decline for a number of crops and regions, but the drivers of this process are poor... more Yields are in decline for a number of crops and regions, but the drivers of this process are poorly known. Global decreases in pollinator abundance and diversity have been proposed as a major driver of yield declines in crops that depend on animals, mostly bees, to produce fruits and seeds. Alternatively, widespread tree mortality has been directly and indirectly related to global climate change, which could also explain yield decreases in tree crops. As tree crops are expected to be more dependent on pollinators than other crop types, disentangling the relative influence of growth form and pollinator dependence is relevant to identify the ultimate factors driving yield declines. The incidence of yield decline, estimated as a negative average yield growth rate from 1961 to 2020, was measured in 4270 time series, involving 136 crops and 163 countries and territories. About one-fourth of all time series showed negative average rates of yield growth, a characteristic associated with both high pollinator dependence and a tree growth form. Because pollinator dependence and plant growth form were partially correlated, we disentangled the effect of each of these two predictors using a series of generalized linear mixed models that evaluated direct and indirect associations. Our analyses revealed a stronger association of yield decline with growth form than with pollinator dependence, a relationship that persisted after partialling out the effect of pollinator dependence. In particular, yield declines were more common among tree than herbaceous and shrub crops in all major regions but in Africa, a continent showing a high incidence of yield declines irrespective of growth form. These results suggest that global climate change rather than pollinator decline could already be impacting tree crop productivity.

Global Ecology and Biogeography, 2022

The exponential growth of the human population often causes the overexploitation of resources and... more 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 (Araucaria araucana) and two seed exploiters: the Austral parakeet (Enicognathus ferrugineus) and human seed collectors. We tested the importance of partial seed consumption by parakeets as an escape to human seed harvesting. Although parakeets frequently ate whole seeds, a substantial proportion of the seeds found under trees were only partially eaten and avoided by human collectors. These seeds germinated at a similar proportion but faster than intact seeds under laboratory conditions. Our results revealed an overlooked mutualism between parakeets and an endangered tree. Incomplete seed eating by parakeets, plus selection against these eaten seeds by humans may enhance regeneration possibilities for this conifer species subject to human seed collection, turning the scale of the antagonism-mutualism continuum to the mutualistic side. In this context, parakeets might be providing an important service in those forests subject to human harvesting by allowing a fraction of seeds to escape human predation

The exponential growth of the human population often causes the overexploitation of resources and... more 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 (Araucaria araucana) and two seed exploiters: the Austral parakeet (Enicognathus ferrugineus) and human seed collectors. We tested the importance of partial seed consumption by parakeets as an escape to human seed harvesting. Although parakeets frequently ate whole seeds, a substantial proportion of the seeds found under trees were only partially eaten and avoided by human collectors. These seeds germinated at a similar proportion but faster than intact seeds under laboratory conditions. Our results revealed an overlooked mutualism between parakeets and an endangered tree. Incomplete seed eating by parakeets, plus selection against these eaten seeds by humans, may enhance regeneration possibilities for this conifer species subject to human seed collection, turning the scale of the antagonism–mutualism continuum to the mutualistic side. In this context, parakeets might be providing an important service in those forests subject to human harvesting by allowing a fraction of seeds to escape human predation.

1. Domestication generally involves two sequential processes: initial identification of wild spec... more 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, domesticated species can differ from wild species and may share characteristics owing to convergent evolution ("domestication syndrome"). Baring evolutionary constraints, domestication selection may generate extreme phenotypes that transcend the "boundaries of nature" evident for wild species. Despite evidence of domestication syndromes in some clades, broader contributions of progenitor filtering and domestication selection to characteristics of contemporary domesticated species have received limited attention. 2. Using comparative analysis of 49 grain-crop and 87 wild annual plant species from 15 families, we: (1) addressed whether plants of crop and wild species differ for mean seed number, per-seed mass and total seed-mass investment; (2) assessed contributions of a) progenitor filtering and b) domestication selection to these differences; (3) evaluated whether crop characteristics exceed the boundaries of nature; and (4) assessed whether seed-production characteristics of grain crops constitute components of a generic domestication syndrome. 3. On average, grain-crop plants produce heavier seeds and greater total seed mass than wild species, but seed number per plant does not differ. Comparison of wild species between genera with or without crop species found no evidence of progenitor filtering. In contrast, crop species differed from congeneric wild species for the mass traits, but not for seed number. Greater seed investment by crops is consistent with artificial selection for enhanced seed yield (mass per harvested area), whereas heavier individual seeds suggest selection for improved nutritional quality and (or) adaptation to cultivation environments. 4. Seed numb [...]

Cryptogamie, Bryologie, 2018

ABSTRACT A new population of the Argentinian endemic Riella choconensis Hässel (Riellaceae, March... more ABSTRACT A new population of the Argentinian endemic Riella choconensis Hässel (Riellaceae, Marchantiophyta) was discovered from a culture of sediments from the Laguna de los Juncos (Río Negro province, Argentina). This species was known previously from two nearby collections, made in 1984, in the type locality at the Ramos Mexía reservoir (Neuquén province) and was not recorded since. Fresh material from the new population enabled detailed morphological analyses, which are extensively described here, illustrated and compared to type material of the species. Based on the smooth female involucre, the species belongs to subgenus Riella Mont. However, cross-sections of this structure showed that R. choconensis has bistratose involucre walls, contrasting with the unistratose female involucres of all other species in the genus. The updated morphological data are integrated into a new key to the identification of the American species of Riella.

Plant Biology, 2017

Variation in flowering phenology is common in natural populations, and is expected to be, togethe... more Variation in flowering phenology is common in natural populations, and is expected to be, together with inter-mate distance, an important driver of effective pollen dispersal. In populations composed by plants with temporally separated sexual phases (i.e. dichogamous or heterodichogamous populations), pollen-mediated gene flow is assumed to reflect phenological overlap between complementary sexual phases. In this study, we conducted paternity analyses to test this hypothesis in the temporally dimorphic tree Acer opalus.  We performed spatially explicit analyses based on categorical and fractional paternity assignment, and we included tree size, pairwise genetic relatedness and morph type as additional predictors. Because differences between morphs in flowering phenology may also influence pollination distances, we allowed for separate pollen dispersal kernels for the two morphs.  Extended phenological overlap between male and female phases (mainly associated with inter-morph crosses) resulted in higher siring success after accounting for the effects of genetic relatedness, morph type and tree size, while reduced phenological overlap (mainly associated with intra-morph crosses) resulted in longer pollination distances achieved. Siring success also increased in larger trees.  Mating patterns could not be predicted by phenology alone. However, as heterogeneity in flowering phenology was the single morph-specific predictor of siring success, it is expected to be key in maintaining the temporal dimorphism in Acer opalus, by promoting not only a prevalent pattern of inter-morph mating, but also long-distance pollination resulting from intra-morph mating events.

Royal Society open science, 2018

The exponential growth of the human population often causes the overexploitation of resources and... more 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 () and two seed exploiters: the Austral parakeet () and human seed collectors. We tested the importance of partial seed consumption by parakeets as an escape from human seed harvesting. Although parakeets frequently ate whole seeds, a substantial proportion of the seeds found under trees were only partially eaten and avoided by human seed collectors. These seeds germinated at a similar proportion but faster than intact seeds under laboratory conditions. Our results revealed an overlooked mutualism between parakeets and an endangered tree. Incomplete seed eating by parakeets, plus selection against these eaten seeds by humans, may enhance rege...

Evolutionary Ecology, 2017

Pollinators are important agents of selection on floral traits, including nectar sugar compositio... more 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 sugar composition, as well as the generality of these associations across the angiosperms, remain unknown. We compiled data on nectar sugar composition for [1000 plant species, along with information on flower visitors, plant growth form and latitudinal climatic zone, to provide the first comprehensive assessment of correlates of variation in sugar nectar composition in the angiosperms. After assembling a phylogeny linking all species in the dataset, we estimated the amount of phylogenetic signal in the percentage of sucrose and, by applying phylogenetically-informed multiple regressions, we evaluated whether nectar composition was influenced either by the main pollinator group, plant growth form, or latitudinal climatic zone. The relative importance of each of these factors was then assessed through model selection based on Akaike information criteria and deviance partitioning analysis. Nectar was dominated by sucrose in 56.8% of all the species, glucose in 16.7%, and fructose in 5.5%. Nectar in the remaining species was characterized by similar proportions of the three sugars. Variation in the proportion of sucrose was highest (*70%) at the intrafamily level, and had a significant but low phylogenetic signal, which partially reflects phylogenetic conservatism of the pollinator niche. After controlling for phylogenetic effects, the proportion of sucrose was mainly related to pollinator type and secondarily to climate. Accordingly, this study indicates that nectar sugar composition shows high evolutionary lability and its variation reflects plant-pollinator associations.

Ecology, Jan 28, 2017

The southernmost parakeet might be enhancing pollination of a dioecious conifer The endangered mo... more The southernmost parakeet might be enhancing pollination of a dioecious conifer The endangered monkey puzzle tree, Araucaria araucana, is a dioecious conifer that, throughout its native range in northwest Patagonia (Argentina and Chile), holds sex-specific interactions with the southernmost parrot in the world, the austral parakeet Enicognathus ferrugineus. This parakeet is known to be an important consumer and disperser of A. araucana's seeds (Tella et al. 2016). During the pollination season, we observed parakeets feeding massively on A. araucana's pollen-loaded male cones (Fig. 1a). With their bodies and feet bathed in pollen (Video S1) parakeets often flew to female trees, perching on receptive female cones, which they did not

Proceedings. Biological sciences, Jan 26, 2017

Conservation biology can profit greatly from incorporating a phylogenetic perspective into analys... more 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 extinction risk assessments following the International Union fo Conservation of Nature Red List categories and criteria, and information on species traits presumably associated with bumblebee decline. We quantified the strength of phylogenetic signal in decline, range size, tongue length and parasite presence. Overall, about one-third of the assessed bumblebees are declining and declining species are not randomly distributed across the Bombus phylogeny. Susceptible species were over-represented in the subgenus Thoracobombus (approx. 64%) and under-represented in the subgenus Pyrobombus (approx. 6%). Phylogenetic logistic regressions revea...

Ecology Letters, 2015

Landscape's human transformation The fertile Austral Pampas' region, where the study sierras are ... more Landscape's human transformation The fertile Austral Pampas' region, where the study sierras are located, was effectively colonized by criollos of Spanish descent between 1820 and 1830, and the land divided among the first "estancieros", whose main activity was cattle-raising. The transformation from pasture to cropland on the plains surrounding the sierras occurred at the end of the 19 th century associated with the onset of the big European immigration to Argentina (Barsky & Gelman 2001). As it happened across the Pampas, a relatively diverse agriculture dominated by wheat was replaced, starting in the late seventies, by one monopolized by soybean (Aizen et al. 2009). Today the sierras emerge as true islands of diversity amidst a relatively uniform agriculture matrix (Fig. 1). Threshold distance Functional connectivity depends on the dispersal capacity of individuals. Thus, it is difficult to determine a priori the threshold distance below which two given habitat patches are expected to be "connected" based solely on theoretical expectations, particularly for community attributes. An empirical approach frequently used in landscape ecological studies is to identify the threshold distance that maximizes the variance explained by the correlation between a given connectivity metric and a population/community attribute (e.g. Steffan-Dewenter et al. 2002). We followed this approach by estimating the relation between phylogenetic signals in interactions and estimates of patch betweenness centrality for each of the 12 focal sierras (Table S1), considering threshold distances between 10 and 20 km (Table S2). This range of distances was chosen because distances <10 km resulted in some sierras to be completely "disconnected" from the rest (i.e. their betweenness S38 Figure S3 (cont.

Conservation Genetics

Fourteen polymorphic microsatellite loci were isolated from the genomic DNA of Pistacia weinmanni... more Fourteen polymorphic microsatellite loci were isolated from the genomic DNA of Pistacia weinmannifolia, using the Fast Isolation by AFLP of Sequences Containing repeats (FIASCO) method, and screened on 12 individuals from each of two wild populations. The 14 polymorphic loci had an average of 4.1 alleles per locus varying from 1 to 9. The observed (H o) and expected (H e) heterozygosities across the two populations ranged from 0.000 to 0.933 and from 0.000 to 0.906, respectively. Tests for departure from Hardy-Weinberg equilibrium (HWE) and genotypic linkage disequilibrium (LD) were conducted for each of the two populations separately. It was found that no locus significantly deviated from HWE proportions and no significant LD was detected between loci (p < 0.001). In the test of cross-species utility, we successfully amplified nine (64.2%) of 14 loci in P. chinensis and four (28.6%) in P. mexicana. The relatively high level of polymorphism for these markers will facilitate further studies of gene flow, population structure and evolutionary history of P. weinmannifolia and its congeners.

Evolutionary Ecology, 2014

Proceedings of the Royal Society B: Biological Sciences, 2011

Pollen fate can strongly affect the genetic structure of populations with restricted gene flow an... more Pollen fate can strongly affect the genetic structure of populations with restricted gene flow and significant inbreeding risk. We established an experimental population of inbred and outbred Silene latifolia plants to evaluate the effects of (i) inbreeding depression, (ii) phenotypic variation and (iii) relatedness between mates on male fitness under natural pollination. Paternity analysis revealed that outbred males sired significantly more offspring than inbred males. Independently of the effects of inbreeding, male fitness depended on several male traits, including a sexually dimorphic (flower number) and a gametophytic trait ( in vitro pollen germination rate). In addition, full-sib matings were less frequent than randomly expected. Thus, inbreeding, phenotype and genetic dissimilarity simultaneously affect male fitness in this animal-pollinated plant. While inbreeding depression might threaten population persistence, the deficiency of effective matings between sibs and the hig...

Molecular Ecology, 2011

Comparative analyses of spatial genetic structure of populations of plants and the insects they i... more Comparative analyses of spatial genetic structure of populations of plants and the insects they interact with provide an indication of how gene flow, natural selection and genetic drift may jointly influence the distribution of genetic variation and potential for local coadaptation for interacting species. Here, we analysed the spatial scale of genetic structure within and among nine populations of an interacting species pair, the white campion Silene latifolia and the moth Hadena bicruris, along a latitudinal gradient across Northern ⁄ Central Europe. This dioecious, short-lived perennial plant inhabits patchy, often disturbed environments. The moth H. bicruris acts both as its pollinator and specialist seed predator that reproduces by laying eggs in S. latifolia flowers. We used nine microsatellite markers for S. latifolia and eight newly developed markers for H. bicruris. We found high levels of inbreeding in most populations of both plant and pollinator ⁄ seed predator. Among populations, significant genetic structure was observed for S. latifolia but not for its pollinator ⁄ seed predator, suggesting that despite migration among populations of H. bicruris, pollen is not, or only rarely, carried over between populations, thus maintaining genetic structure among plant populations. There was a weak positive correlation between genetic distances of S. latifolia and H. bicruris. These results indicate that while significant structure of S. latifolia populations creates the potential for differentiation at traits relevant for the interaction with the pollinator ⁄ seed predator, substantial gene flow in H. bicruris may counteract this process in at least some populations.

cma.gva.es

Page 1. 9 Biología reproductiva de Acer opalus subsp. granatense Gabriela Gleiser1 y Miguel Verdú... more Page 1. 9 Biología reproductiva de Acer opalus subsp. granatense Gabriela Gleiser1 y Miguel Verdú1 1 Centro de investigaciones sobre desertificación (CSIC - Universidad de Valencia - Generalitat Valenciana). Camí de la Marjal S/N. Apartado oficial 46470. Albal. Valencia. ...

International Journal of Plant Sciences, 2019

Premise of research. Sexual functions in gymnosperms are mostly performed by separate reproductiv... more 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 uncoupled. Studies on the fossil record of the conifer family Araucariaceae revealed important morphological changes occurring in reproductive cones. Here, we explored the pattern of evolution of male and female cone sizes in Araucariaceae, with a special focus on Araucaria-the most variable and widespread genus in the family. Methodology. We gathered data on male and female cone sizes from fossils and extant Araucariaceae species. Focusing on Araucaria, we analyzed whether cone sizes are phylogenetically structured. Furthermore, we compared the evolutionary trajectories of male and female cone sizes by evaluating the goodness of fit of different evolutionary models. Finally, we evaluated whether different selective regimes across the phylogeny could have shaped cone morphology. Pivotal results. Size changes in Araucariaceae occurred in both male and female cones, with the largest cones appearing in extant Araucaria. In this genus, different evolutionary models best described cone size changes, with male cone evolution best described by a model not influenced by phylogeny and female cone evolution by a stabilizing selection model with two optima. This resulted in contrasting phylogenetic signals, with female cone size being more phylogenetically structured than male cone size. Conclusions. Changes in cone size in Araucariaceae occurred in both male and female cones. The largest male and female cones appeared in Araucaria through uncoupled evolutionary pathways, both involving a natural selection component as a driver of evolutionary change. A contrasting pattern of phylogenetic signal in male and female cone size reflected the uncoupled evolutionary trajectories followed by these sexual structures.

bioRxiv (Cold Spring Harbor Laboratory), Apr 29, 2023

Global Ecology and Biogeography, 2022

The exponential growth of the human population often causes the overexploitation of resources and... more 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 (Araucaria araucana) and two seed exploiters: the Austral parakeet (Enicognathus ferrugineus) and human seed collectors. We tested the importance of partial seed consumption by parakeets as an escape to human seed harvesting. Although parakeets frequently ate whole seeds, a substantial proportion of the seeds found under trees were only partially eaten and avoided by human collectors. These seeds germinated at a similar proportion but faster than intact seeds under laboratory conditions. Our results revealed an overlooked mutualism between parakeets and an endangered tree. Incomplete seed eating by parakeets, plus selection against these eaten seeds by humans, may enhance regeneration possibilities for this conifer species subject to human seed collection, turning the scale of the antagonism–mutualism continuum to the mutualistic side. In this context, parakeets might be providing an important service in those forests subject to human harvesting by allowing a fraction of seeds to escape human predation.

Cryptogamie, Bryologie, 2018

Plant Biology, 2017

Royal Society open science, 2018

The exponential growth of the human population often causes the overexploitation of resources and... more 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 () and two seed exploiters: the Austral parakeet () and human seed collectors. We tested the importance of partial seed consumption by parakeets as an escape from human seed harvesting. Although parakeets frequently ate whole seeds, a substantial proportion of the seeds found under trees were only partially eaten and avoided by human seed collectors. These seeds germinated at a similar proportion but faster than intact seeds under laboratory conditions. Our results revealed an overlooked mutualism between parakeets and an endangered tree. Incomplete seed eating by parakeets, plus selection against these eaten seeds by humans, may enhance rege...

Evolutionary Ecology, 2017

Ecology, Jan 28, 2017

Proceedings. Biological sciences, Jan 26, 2017

Ecology Letters, 2015

Conservation Genetics

Evolutionary Ecology, 2014

Proceedings of the Royal Society B: Biological Sciences, 2011

Molecular Ecology, 2011

cma.gva.es

International Journal of Plant Sciences, 2019