Papers by Marcelo Kittlein
Mammalian Biology
Several components of individual condition can modulate immune function in vertebrates. One of th... more Several components of individual condition can modulate immune function in vertebrates. One of the most common techniques used by ecologists to estimate immune responsiveness in wild populations is the phytohemagglutinin (PHA)-skin test, which is usually considered a proxy of cell-mediated activity. To determine the influence of individual condition on the magnitude of this immune index we assessed the variability in the inflammatory response to PHA in the subterranean solitary rodent, Ctenomys talarum (Talas tuco-tucos), including 18 variables associated with different aspects of individual condition that are indicative of physical, physiological, parasitological and immunological state. A partial least square (PLS) regression analysis was performed on the condition and the response variables to identify those having greater contribution to overall variation in the response. The first two components explained together 77.5% of the maximum achievable explained variance in the inflammatory response to PHA (60% of total variance). Abundance of eggs of Trichuris pampeana, eosinophil, monocyte and neutrophil counts, together with reproductive condition were identified as the most important variables affecting the inflammatory response. The first component negatively associated the inflammatory response to PHA with the abundance of the nematode T. pampeana, and with counts of eosinophils and monocytes. The second component negatively associated the inflammatory response to PHA with reproductive condition, neutrophils and eosinophils. We discuss the general negative effect of infection on the immune responsiveness of wild animals and highlight the usefulness of the multivariate approaches in providing information on physiology, parasitology and health relationships to assess patterns of variation in immune responses.
Mastozoología Neotropical
Developmental Psychobiology
Prey species exposed to predator-derived odors have shown alterations in foraging, feeding, gener... more Prey species exposed to predator-derived odors have shown alterations in foraging, feeding, general activity, and, mainly in females, reproduction (Apfelbach et al., 2005), although negative results were also described depending upon prey life history (Orrock, 2010) These changes may be accompanied by an impact on the regulation of the hypothalamic-pituitary-adrenal (HPA) axis, with increased levels of stress hormones such as glucocorticoids (GCs) and adrenocorticotrophic hormone (ACTH)
Mastozoología Neotropical
Genetica
Studies of genetic differentiation in fragmented environments help us to identify those landscape... more Studies of genetic differentiation in fragmented environments help us to identify those landscape features that most affect gene flow and dispersal patterns. Particularly, the assessment of the relative significance of intrinsic biological and environmental factors affecting the genetic structure of populations becomes crucial. In this work, we assess the current dispersal patterns and population structure of Ctenomys "chasiquensis", a vulnerable and endemic subterranean rodent distributed on a small area in Central Argentina, using 9 polymorphic microsatellite loci. We use landscape genetics approaches to assess the relationship between genetic connectivity among populations and environmental attributes. Our analyses show that populations of C. "chasiquensis" are moderately to highly structured at a regional level. This pattern is most likely the outcome of substantial gene flow on the more homogeneous sand dune habitat of the Northwest of its distributional range, in conjunction with an important degree of isolation of eastern and southwestern populations, where the optimal habitat is surrounded by a highly fragmented landscape. Landscape genetics analysis suggests that habitat quality and longitude were the environmental factors most strongly associated with genetic differentiation/uniqueness of populations. In conclusion, our results indicate an important genetic structure in this species, even at a small spatial scale, suggesting that contemporary habitat fragmentation increases population differentiation.
Mammalian Biology - Zeitschrift für Säugetierkunde
Genetica, 2016
In this study we combine information from landscape characteristics, demographic inference and sp... more In this study we combine information from landscape characteristics, demographic inference and species distribution modelling to identify environmental factors that shape the genetic distribution of the fossorial rodent Ctenomys. We sequenced the mtDNA control region and amplified microsatellites from 27 populations distributed across the Iberá wetland ecosystem. Hierarchical Bayesian modelling was used to construct phylogenies and estimate divergence times. We developed species distribution models to determine what climatic variables and soil parameters predicted species presence by comparing the current to the historic and predicted future distribution of the species. Finally, we explore the impact of environmental variables on the genetic structure of Ctenomys based on current and past species distributions. The variables that consistently correlated with the predicted distribution of the species and explained the observed genetic differentiation among populations included the distribution of well-drained sandy soils and temperature seasonality. A core region of stable suitable habitat was identified from the Last Interglacial, which is projected to remain stable into the future. This region is also the most genetically diverse and is currently under strong anthropogenic pressure. Results reveal complex demographic dynamics, which have been in constant change in both time and space, and are likely linked to the evolution of the Paraná River. We suggest that any alteration of soil properties (climatic or anthropic) may significantly impact the availability of suitable habitat and consequently the ability of individuals to disperse. The protection of this core stable habitat is of prime importance given the increasing levels of human disturbance across this wetland system and the threat of climate change.
Evolutionary Ecology, 2000
We studied habitat preferences and intra and interspeci®c density-dependent eects on habitat sele... more We studied habitat preferences and intra and interspeci®c density-dependent eects on habitat selection by Akodon azarae and Calomys laucha between maize ®elds and their adjacent borders, during dierent developmental stages of the crop. Akodon azarae detected quantitative dierences between habitats, using preferentially borders throughout the year, while C. laucha perceived borders and crop®elds as quantitatively similar during spring and summer and it detected borders as quantitatively better at the high density period (autumn and winter). These results support the prediction of dierential habitat preferences as a model of community organisation at the low density period, while they are consistent with shared habitat preferences during autumn and winter when both species apparently coexist in the better habitat (border). Akodon azarae showed intraspeci®c density-dependent habitat selection throughout the year, except in spring, while habitat selection by C. laucha was density-dependent in spring, autumn and winter. The eect of interspeci®c density on habitat selection was detected in both habitats and changed seasonally. The eect of A. azarae over C. laucha by resources exploitation was detected in borders, while competitive eects of C. laucha over A. azarae was observed within crop®elds. Both species were more aected by exploitation competition than interference, which was more common in borders than in maize ®elds. We conclude that seasonally have a profound eect in habitat selection of these species because it changes the intensity of intra and interspeci®c competition and aects dierent habitat preferences and basic suitability of habitats.
Landscape Ecology, Jul 1, 2009
... To assess the statistical accuracy of this procedure to determine potential habitat for C. po... more ... To assess the statistical accuracy of this procedure to determine potential habitat for C. porteousi we compared our results to a classification of habitat developed using program MaxEnt (Phillips et al. 2006). We used all bands from the two Landsat ETM? ...
Mammalian Biology - Zeitschrift für Säugetierkunde, 2016
Mastozoologia Neotropical, 2013
Proyecto académico sin fines de lucro, desarrollado bajo la iniciativa de acceso abierto
In book: Manejo de fauna silvestre en Amanonia y Latinoamerica, Publisher: pp. 219-236, Editors: ... more In book: Manejo de fauna silvestre en Amanonia y Latinoamerica, Publisher: pp. 219-236, Editors: Cabrera E., Mercolli C., R. Resquin
Journal of Sea Research, 2015
ABSTRACT The invasive shrimp Palaemon macrodactylus is associated mainly with brackish waters. Pr... more ABSTRACT The invasive shrimp Palaemon macrodactylus is associated mainly with brackish waters. Previous studies raised the question if tolerance to low salinities differs between larvae and adults. To answer this question, the combined effects of two temperatures (20 and 25 °C) and four salinities (5, 12, 23 and 34 psu) on survival and development of larvae that hatched at the beginning, in the midpoint and near the end of a reproductive season (denotedearly,middleseasonandlatelarvaerespectively)wereexamined.Thethreetypesoflarvaewereableto surviveandreachjuvenilephaseatsalinitiesbetween 12 and34psuandatbothtemperatures.At5psualllarvae died, but 45% molted at least once. Temperature and salinity to a lesser extent, had effects on the duration of developmentandonthenumberoflarvalstagesinalllarvaltypes.Developmentwaslongeratthelowertemper-ature, especially in middle season and late larvae. Most early larvae reached the juvenile phase through 5 larval stages;thenumberoflarvalstagesofmiddleseasonandlatelarvaewashigherat20°Candinlatelarvaealsolow salinity produced extra stages. Low salinity (12 psu) and, in early and middle season larvae, low temperature produced lighter and smaller individuals. Response of larvae to environmental factors seems to be related in part to theprevious conditions (maternal effects and/or embryo development conditions).The narrower salinity tolerance of larvae compared to adults and the ability of zoea I to survive at least some days at 5 psu may be related with an export larval strategy.
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Papers by Marcelo Kittlein