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Xalapa de Enríquez, Mexico

Laundre J.W.,Idaho State University | Laundre J.W.,Institute Ecologia
Ecology | Year: 2010

The predator-prey shell game predicts random movement of prey across the landscape, whereas the behavioral response race and landscape of fear models predict that there should be a negative relationship between the spatial distribution of a predator and its behaviorally active prey. Additionally, prey have imperfect information on the whereabouts of their predator, which the predator should incorporate in its patch use strategy. I used a onepredator-one-prey system, puma (Puma concolor)-mule deer (Odocoileus hemionus) to test the following predictions regarding predator-prey distribution and patch use by the predator. (1) Pumas will spend more time in high prey risk/low prey use habitat types, while deer will spend their time in low-risk habitats. Pumas should (2) select large forage patches more often, (3) remain in large patches longer, and (4) revisit individual large patches more often than individual smaller ones. I tested these predictions with an extensive telemetry data set collected over 16 years in a study area of patchy forested habitat. When active, pumas spent significantly less time in open areas of low intrinsic predation risk than did deer. Pumas used large patches more than expected, revisited individual large patches significantly more often than smaller ones, and stayed significantly longer in larger patches than in smaller ones. The results supported the prediction of a negative relationship in the spatial distribution of a predator and its prey and indicated that the predator is incorporating the prey's imperfect information about its presence. These results indicate a behavioral complexity on the landscape scale that can have far-reaching impacts on predator-prey interactions. © 2010 by the Ecological Society of America.

Pineda E.,Institute Ecologia | Pineda E.,CSIC - National Museum of Natural Sciences | Lobo J.M.,CSIC - National Museum of Natural Sciences
Global Ecology and Biogeography | Year: 2012

Aim The method used to generate hypotheses about species distributions, in addition to spatial scale, may affect the biodiversity patterns that are then observed. We compared the performance of range maps and MaxEnt species distribution models at different spatial resolutions by examining the degree of similarity between predicted species richness and composition against observed values from well-surveyed cells (WSCs). Location Mexico. Methods We estimated amphibian richness distributions at five spatial resolutions (from 0.083° to 2°) by overlaying 370 individual range maps or MaxEnt predictions, comparing the similarity of the spatial patterns and correlating predicted values with the observed values for WSCs. Additionally, we looked at species composition and assessed commission and omission errors associated with each method. Results MaxEnt predictions reveal greater geographic differences in richness between species rich and species poor regions than the range maps did at the five resolutions assessed. Correlations between species richness values estimated by either of the two procedures and the observed values from the WSCs increased with decreasing resolution. The slopes of the regressions between the predicted and observed values indicate that MaxEnt overpredicts observed species richness at all of the resolutions used, while range maps underpredict them, except at the finest resolution. Prediction errors did not vary significantly between methods at any resolution and tended to decrease with decreasing resolution. The accuracy of both procedures was clearly different when commission and omission errors were examined separately. Main conclusions Despite the congruent increase in the geographic richness patterns obtained from both procedures as resolution decreases, the maps created with these methods cannot be used interchangeably because of notable differences in the species compositions they report. © 2012 Blackwell Publishing Ltd.

Santiago-Alarcon D.,Institute Ecologia | Santiago-Alarcon D.,Albert Ludwigs University of Freiburg | Palinauskas V.,Institute of Ecology | Schaefer H.M.,Albert Ludwigs University of Freiburg
Biological Reviews | Year: 2012

Haemosporida is a large group of vector-borne intracellular parasites that infect amphibians, reptiles, birds, and mammals. This group includes the different malaria parasites (Plasmodium spp.) that infect humans around the world. Our knowledge on the full life cycle of these parasites is most complete for those parasites that infect humans and, to some extent, birds. However, our current knowledge on haemosporidian life cycles is characterized by a paucity of information concerning the vector species responsible for their transmission among vertebrates. Moreover, our taxonomic and systematic knowledge of haemosporidians is far from complete, in particular because of insufficient sampling in wild vertebrates and in tropical regions. Detailed experimental studies to identify avian haemosporidian vectors are uncommon, with only a few published during the last 25 years. As such, little knowledge has accumulated on haemosporidian life cycles during the last three decades, hindering progress in ecology, evolution, and systematic studies of these avian parasites. Nonetheless, recently developed molecular tools have facilitated advances in haemosporidian research. DNA can now be extracted from vectors' blood meals and the vertebrate host identified; if the blood meal is infected by haemosporidians, the parasite's genetic lineage can also be identified. While this molecular tool should help to identify putative vector species, detailed experimental studies on vector competence are still needed. Furthermore, molecular tools have helped to refine our knowledge on Haemosporida taxonomy and systematics. Herein we review studies conducted on Diptera vectors transmitting avian haemosporidians from the late 1800s to the present. We also review work on Haemosporida taxonomy and systematics since the first application of molecular techniques and provide recommendations and suggest future research directions. Because human encroachment on natural environments brings human populations into contact with novel parasite sources, we stress that the best way to avoid emergent and reemergent diseases is through a program encompassing ecological restoration, environmental education, and enhanced understanding of the value of ecosystem services. © 2012 The Authors. Biological Reviews © 2012 Cambridge Philosophical Society.

Valiente-Banuet A.,Institute Ecologia | Valiente-Banuet A.,National Autonomous University of Mexico | Verdu M.,University of Valencia
Annual Review of Ecology, Evolution, and Systematics | Year: 2013

The relationship between facilitation and evolutionary ecology is poorly understood. We review five issues elucidating how the phylogenetic relatedness of species provides insight into the role of facilitation in community assembly: (a) Are the facilitative interactions more common between species that differ in a regeneration niche? (b) Are facilitative interactions more common between distantly related species? (c) Do communities governed by facilitation (rather than competition) have higher phylogenetic diversity? (d) As facilitated juvenile plants mature, do they compete with their nurses more often if they are closely related to them? (e) How does the phylogenetic signature in a community reveal ecological processes, such as succession, regeneration dynamics, indirect interactions, and coextinction cascades? The evolutionary history of lineages explains the regeneration niche of species, which ultimately determines the facilitation-competition balance and therefore community assembly and dynamics. We apply this framework to the conservation of biodiversity and propose future research avenues. © Copyright ©2013 by Annual Reviews. All rights reserved.

Purpose: In this study, we quantified soil organic carbon (SOC) stocks and analyzed their relationship with biophysical factors and soil properties. Materials and methods: The study region was Veracruz State, located in the eastern part of Mexico, covering an area of 72,410 km2. A soil database that contains physicochemical analyses of soil horizons such as carbon concentration data was the source of information used in this study. The database consisted of 163 soil profiles representing 464 genetic horizons. Statistical analysis was used to investigate the effect of each factor (climate, altitude, slope) on SOC stock to 0.50 m depth and to assess differences in the distribution of SOC stock in terms of soil depth (0.0-0.20, 0.20-0.40, 0.40-0.60, 0.60-0.80, 0.80-1.0 m) and land use. In order to compute the spatial distribution of SOC stock to 0.50 m depth based on the soil sampling location, the kriging method was used. Results and discussion: Results indicated that SOC stock (0.50 m depth) ranged between 0.44 and 41.2 kg C m-2. Regression analysis showed that SOC stocks (0.50 m depth) are negatively correlated with temperature (r = -0.38; P < 0.001) and positively correlated with altitude (r = 0.40; P < 0.001) and slope (r = 0.40; P < 0.001). In addition, by multiple regression, temperature combined with precipitation explained more SOC stock variations (r = 0.43; P < 0.001) than the regression model with precipitation (r = 0.13; P = 0.16) alone. Also, slope combined with temperature and precipitation explained more SOC stock variations (r = 0.46; P < 0.001) than the regression model with slope alone. Forest lands, grasslands, and croplands have higher SOC stocks in the 0.0-0.20-m soil layer than in deeper layers. On average, forest lands, grasslands, croplands, and other lands (wetland and dunes) had a SOC stock of 13.6, 14.6, 15.1, and 8.5 kg C m-2 at 1 m depth, respectively. Soil color correlated (-0.25 ≤ r ≤ -0.89) with SOC content. Conclusions: Overall, these results indicate the influence of major interactions between biophysical factors and SOC stocks. This research indicated that SOC stock decreased with soil depth, but with slight variations depending on land use. Thus, there remains a need for more SOC data that include an improved distribution of soil sampling points in order to entirely understand the contributions of biophysical factors to SOC stocks in Veracruz State. © 2014 Springer-Verlag Berlin Heidelberg.

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