DSpace Angular :: Browsing by Author "Maldonado, Karin"

Browsing by Author "Maldonado, Karin"

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A multi-isotope approach reveals seasonal variation in the reliance on marine resources, production of metabolic water, and ingestion of seawater by two species of coastal passerine to maintain water balance
(2023) Navarrete, Lucas; Lubcker, Nico; Alvarez, Felipe; Nespolo, Roberto; Sanchez-Hernandez, Juan Carlos; Maldonado, Karin; Sharp, Zachary D.; Whiteman, John P.; Newsome, Seth D.; Sabat, Pablo
Tracing how free-ranging organisms interact with their environment to maintain water balance is a difficult topic to study for logistical and methodological reasons. We use a novel combination of triple-oxygen stable isotope analyses of water extracted from plasma (delta O-16, delta O-17, delta O-18) and bulk tissue carbon (delta C-13) and nitrogen (delta N-15) isotopes of feathers and blood to estimate the proportional contribution of marine resources, seawater, and metabolic water used by two species of unique songbirds (genus Cinclodes) to maintain their water balance in a seasonal coastal environment. We also assessed the physiological adjustments that these birds use to maintain their water balance. In agreement with previous work on these species, delta C-13 and delta N-15 data show that the coastal resident and invertivore C. nigrofumosus consumes a diet rich in marine resources, while the diet of migratory C. oustaleti shifts seasonally between marine (winter) to freshwater aquatic resources (summer). Triple-oxygen isotope analysis (Delta O-17) of blood plasma, basal metabolic rate (BMR), and total evaporative water loss (TEWL) revealed that similar to 25% of the body water pool of both species originated from metabolic water, while the rest originated from a mix of seawater and fresh water. Delta O-17 measurements suggest that the contribution of metabolic water tends to increase in summer in C. nigrofumosus, which is coupled with a significant increase in BMR and TEWL. The two species had similar BMR and TEWL during the austral winter when they occur sympatrically in coastal environments. We also found a positive and significant association between the use of marine resources as measured by delta C-13 and delta N-15 values and the estimated delta O-18 values of ingested (pre-formed) water in both species, which indicates that Cinclodes do not directly drink seawater but rather passively ingest when consuming marine invertebrates. Finally, results obtained from physiological parameters and the isotope-based estimates of marine (food and water) resource use are consistent, supporting the use of the triple-oxygen isotopes to quantify the contribution of water sources to the total water balance of free-ranging birds.
Diet and habitat aridity affect osmoregulatory physiology: An intraspecific field study along environmental gradients in the Rufous-collared sparrow
(2009) Sabat, Pablo; Gonzalez-Vejares, Sandra; Maldonado, Karin
The urine field osmolality in Zonotrichia capensis along a latitudinal gradient in rainfall and temperature in Chile was examined. We also investigated latitudinal variation in the renal traits that mediate how these birds cope with dehydration. We used the delta N-15 of this species' tissue to investigate whether the reliance on animals and seeds varied among birds and if it had any effect on excretion and renal traits. We found a significant latitudinal variation in urine osmolality, a variable that was correlated with habitat aridity. We also found that the kidney size and proportion of kidney devoted to medullary tissue differed between birds from and and mesic localities, but not in a lineal fashion with aridity. The increment in the position in the food web, as measured by delta N-15, led to an increment in urine osmolality, without changes in kidney features. Our data suggested that differences in dietary habits in the field could be not extended enough to cause changes in the kidney structure in Rufous-collared sparrows. (C) 2008 Elsevier Inc. All rights reserved.
Energetic costs and implications of the intake of plant secondary metabolites on digestive and renal morphology in two austral passerines
(2016) Barcelo, Gonzalo; Manuel Rios, Juan; Maldonado, Karin; Sabat, Pablo
Seed-eating birds have a diet of high nutritional value; however, they must cope with plant secondary metabolites (PSM). We postulated that the detoxification capacity of birds is associated with a metabolic cost, given that the organs responsible for detoxification significantly contribute to energetic metabolism. We used an experimental approach to assess the effects of phenol-enriched diets on two passerines with different feeding habits: the omnivorous rufous-collared sparrow (Zonotrichia capensis) and the granivorous common diuca-finch (Diuca diuca). The birds were fed with one of three diets: control diet, supplemented with tannic acid, or supplemented with Opuntia ficus-indica phenolic extract (a common food of the sparrow but not the finch). After 5 weeks of exposure to the diets, we measured basal metabolic rates (BMR), energy intake, glucuronic acid output and digestive and kidney structure. In both species, detoxification capacity expressed as glucuronic acid output was higher in individuals consuming phenol-enriched diets compared to the control diet. However, whereas sparrows increase energy intake and intestinal mass when feeding on phenol-enriched diets, finches had lower intestinal mass and energy intake remains stable. Furthermore, sparrows had higher BMR on phenolenriched diets compared to the control group, whereas in the finches BMR remains unchanged. Interspecific differences in response to phenols intake may be determined by the dietary habits of these species. While both species can feed on moderate phenolic diets for 5 weeks, energy costs may differ due to different responses in food intake and organ structure to counteract the effects of PSM intake.
Feeding and digestive responses to fatty acid intake in two South American passerines with different food habits
(2014) Manuel Rios, Juan; Barcelo, Gonzalo F.; Narvaez, Cristobal; Maldonado, Karin; Sabat, Pablo
Specific fatty acids (FA) such as unsaturated (UFA) and saturated (SFA) fatty acids contained in foods are key factors in the nutritional ecology of birds. By means of a field and experimental approach, we evaluated the effect of diet on the activity of three esterases involved in FA hydrolysis; carboxylesterase (CE: 4-NPA-CE and a-NA-CE) and butyrylcholinesterase, in two South American passerines: the omnivorous rufous-collared sparrow (Zonotrichia capensis) and the granivorous common diuca-finch (Diuca diuca). The activity of the three esterases was measured in the intestines of freshly caught individuals over two distinct seasons and also after a chronic intake of a UFA-rich or SFA-rich diet in the laboratory. In turn, we assessed the feeding responses of the birds choosing amongst diets contrasting in the kind of specific FA (UFA- vs. SFA-treated diets). During summer, field CE activities (4-NPA-CE and a-NA-CE) in the small intestine were higher in the rufous-collared sparrow (25.3 +/- A 3.3 and 81.4 +/- A 10.8 A mu mol min(-1) g tissue(-1), respectively) than in the common diuca-finch (10.0 +/- A 3.0 and 33.9 +/- A 13.1 A mu mol min(-1) g tissue(-1), respectively). Two hour feeding trial test indicated that both species exhibited a clear preference for UFA-treated diets. On average, the rufous-collared sparrow consumed 0.46 g 2 h(-1) of UFA-rich diets and 0.12 g 2 h(-1) of SFA-rich diets. In turn, the consumption pattern of the common diuca-finch averaged 0.73 and 0.16 g 2 h(-1) for UFA-rich and SFA-rich diets, respectively. After a month of dietary acclimation to UFA-rich and SFA-rich diets, both species maintained body mass irrespective of the dietary regime. Additionally, the intestinal 4-NPA-CE activity exhibited by birds fed on a UFA-rich or SFA-rich diet was higher in the rufous-collared sparrow (39.0 +/- A 5.3 and 44.2 +/- A 7.3 A mu mol min(-1) g tissue(-1), respectively) than in the common diuca-finch (13.3 +/- A 1.9 and 11.2 +/- A 1.4 A mu mol min(-1) g tissue(-1), respectively). Finally, the intestinal a-NA-CE activity exhibited by the rufous-collared sparrow was about two times higher when consuming an UFA-rich diet. Our results suggest that the rufus-collared sparrow exhibits a greater capacity for intestinal FA hydrolysis, which would allow it to better deal with fats from different sources.
Geographic Variation in the Association between Exploratory Behavior and Physiology in Rufous-Collared Sparrows
(2012) Maldonado, Karin; van Dongen, Wouter F. D.; Vasquez, Rodrigo A.; Sabat, Pablo
Increasing research has attempted to clarify the links between animal personality and physiology. However, the mechanisms driving this association remain largely unknown, and knowledge of how ecological factors may affect its direction and strength is scant. In this study, we quantified variation in the association between exploratory behavior, basal metabolic rate (BMR), and total evaporative water loss (TEWL) in rufous-collared sparrows (Zonotrichia capensis) inhabiting desert, Mediterranean, and cold-temperate climates. We found that the exploratory behavior score was highest in birds from the cold-temperate site, which was characterized by a moderate level of ecological variability (seasonality). Moreover, the association between exploratory behavior and physiological variables differed among localities. Only birds from the Mediterranean site showed a positive correlation between exploratory behavior and BMR. We found no association between exploration and TEWL at any study site. Our findings suggest that differences in the ecological conditions experienced by each sparrow population result in a particular combination of behavioral and physiological traits. An understanding of this intraspecific variation along ecological gradients provides unique insights into how specific ecological conditions affect the coupling of behavioral and physiological traits and the mechanisms underlying that relationship.
Geographic variation in the repeatability of a personality trait
(2010) van Dongen, Wouter F. D.; Maldonado, Karin; Sabat, Pablo; Vasquez, Rodrigo A.
Animal personalities are interindividual behavioral differences that are consistent across time or contexts. Increasing research is revealing the adaptive significance of personalities, although the mechanisms driving this variation remain largely unknown. A possible source of variation in personality traits is interpopulational differences in the strength of selection acting upon them. The response to selection can be measured indirectly via the behavior's repeatability, as repeatability generally sets an upper limit to trait heritability. However, no information currently exists on geographic variation in personality repeatability. We therefore quantified repeatability in exploratory behavior, a common personality trait, over multiple trials for 3 populations of rufous-collared sparrow (Zonotrichia capensis), focusing on 3 specific measures (exploration speed, diversity of perches visited, and number of hops). We also asked how differences in repeatability of these 3 measures affect other aspects of exploration, such as the temporal consistency of intercorrelations between the measures. Exploration speed was highly repeatable across all populations, whereas diversity was only repeatable in 2 of 3 populations and hopping behavior not at all. These differences in repeatability lead to temporal variation in the correlation matrices of the 3 exploration measures. Finally, only trial number influenced interindividual variability in exploration, whereas population identity, experimental conditions (i.e., conducting the novel environment assay under laboratory or field conditions), and time since capture all had no effect. Our findings highlight the complexity of using measures of behavioral consistency as a definition of personalities and emphasize the value of quantifying interpopulational patterns of trait repeatability.
Individual diet specialisation in sparrows is driven by phenotypic plasticity in traits related to trade-offs in animal performance
(2019) Maldonado, Karin; Newsome, Seth D.; Razeto-Barry, Pablo; Manuel Rios, Juan; Piriz, Gabriela; Sabat, Pablo
Individual diet specialisation (IS) is frequent in many animal taxa and affects population and community dynamics. The niche variation hypothesis (NVH) predicts that broader population niches should exhibit greater IS than populations with narrower niches, and most studies that examine the ecological factors driving IS focus on intraspecific competition. We show that phenotypic plasticity of traits associated with functional trade-offs is an important, but unrecognised mechanism that promotes and maintains IS. We measured nitrogen isotope (delta N-15) and digestive enzyme plasticity in four populations of sparrows (Zonotrichia capensis) to explore the relationship between IS and digestive plasticity. Our results show that phenotypic plasticity associated with functional trade-offs is related in a nonlinear fashion with the degree of IS and positively with population niche width. These findings are opposite to the NVH and suggest that among individual differences in diet can be maintained via acclimatisation and not necessarily require a genetic component.
Osmoregulatory capacity and the ability to use marine food sources in two coastal songbirds (Cinclodes
(2006) Sabat, Pablo; Maldonado, Karin; Farina, Jose Miguel; del Rio, Carlos Martinez
Cinclodes nigrofumosus and C. oustaleti are two closely related songbirds that inhabit the northern Chilean coast during the austral fall and winter. This stretch spans a dramatic north to south latitudinal gradient in rainfall and temperature. Whereas C. nigrofumosus lives exclusively on coastal environments, C. oustaleti shifts seasonally from coastal environments to inland freshwater ones. We used the delta C-13 of these two species' tissues to investigate whether the reliance on marine versus terrestrial sources varied from the hyperarid north to the wet south. We also investigated latitudinal variation in the renal traits that mediate how these birds cope with dehydration and a salty marine diet. Both species increased the incorporation of terrestrial carbon, as measured by 613 C, as terrestrial productivity increased southwards. However, C. nigrofumosus had consistently more positive (i.e. more marine) and less variable delta C-13 values than C. oustaleti. The osmoregulatory traits of both species varied with latitude as well. Urine osmolality decreased from extremely high values in the north to moderate values in the south, while C. nigrofumosus produced more concentrated urine than C. oustaleti. In both species, the proportion of kidney devoted to medullary tissue decreased from north to south, and kidney size increased significantly with latitude. Cinclodes nigrofumosus had larger kidneys with larger proportions of medullary tissue than C. oustaleti. C. nigrofumosus and C. oustaleti are terrestrial organisms subsidized by a rich marine environment where it is adjacent to an unproductive terrestrial. Variation in the reliance on marine food sources seems to be accompanied by adjustments in the osmoregulatory mechanisms used by these birds to cope with salt and dehydration.
Temporal variation in isotopic composition of Pygoscelis penguins at Ardley Island, Antarctic: Are foraging habits impacted by environmental change?
(2017) Negrete, Pablo; Sallaberry, Michel; Barcelo, Gonzalo; Maldonado, Karin; Perona, Franco; McGill, Rona A. R.; Quillfeldt, Petra; Sabat, Pablo
Several studies have suggested that penguins are undergoing a major restructuring of their feeding habits and distribution after drastic climatic changes in the Antarctic Peninsula region. With the objective of estimating potential medium-term and inter-annual variations in trophic niche, we measured delta N-15 and delta C-13 in feather samples of pygoscelid penguins from museum specimens (1982-1984) and in blood and feather samples from 2009/10-2011 collected from animals on Ardley Island. Current penguin feathers had lower delta C-13 and delta N-15 values and were more similar to Antarctic krill values, than feathers in 1982-1984 and blood from 2009/10-2011. Moreover, delta C-13 and delta N-15 values from museum feathers and modern samples occupied a larger isotopic space in Gentoo Penguins (Pygoscelis papua), compared to Ad,lie Penguins (Pygoscelis adeliae) and Chinstrap Penguins (Pygoscelis antarctica). Our results from feathers samples indicated that penguins have decreased their consumption of fish and other prey of higher trophic levels in the early interbreeding period (EIBP), while increasing the amount of euphausiids (Antarctic krill Euphausia superba) taken. The isotopic values of the species suggest that foraging sites varied significantly over time and seasonally. We suggest that environmental changes may have modified the feeding habits of pygoscelid penguins, resulting in changed foraging behaviour in the EIBP, and altering the secondary prey consumption. Prey choice in breeding pygoscelid species is probably limited by the foraging range around the breeding colony and competitive exclusion between congeners.
Testing the niche variation hypothesis in a community of passerine birds
(2017) Maldonado, Karin; Bozinovic Kuscevic, Francisco; Newsome, Seth D.; Sabat, Pablo

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