The study, led by Mauricio Bonilla-Flores of the Institute of Geosystems and Bioindication at Technische Universität Braunschweig together with colleagues from Kiel, Jena, Aachen, and the Chinese Academy of Sciences, focused on the genus Heterocypris, one of the most diverse groups within the family Cyprididae with 72 known species. The team cultured three asexual species under identical laboratory conditions: Heterocypris exodonta from a temporary pond near Nam Co on the Tibetan Plateau at an altitude of 4728 meters, Heterocypris incongruens from a flowerpot in southern Mexico City, and Heterocypris salina from the Botanical Garden in Braunschweig, Germany. By raising all three under the same temperature range of 18 to 23 degrees Celsius and a fixed light cycle, the researchers could separate genuine species differences from environmental noise.

What emerged was a remarkably consistent developmental blueprint. All three species passed through nine distinct stages: eight juvenile instars and one adult stage, each separated by a molt in which the animal sheds its old shell and grows a new, larger one. The smallest juveniles, at stage A-8, measured only around 180 to 220 micrometers in valve length, barely visible to the naked eye. Adults, by contrast, reached over a millimeter in length. Heterocypris incongruens proved the largest of the three, with adult right valves averaging 1349 micrometers, while H. salina was the smallest at 1039 micrometers. These numbers may sound esoteric, but they form the reference library that paleontologists need to identify which species, and which life stages, are preserved in ancient sediments.

One of the most striking findings concerns the surface texture of the juvenile shells. Under scanning electron microscopy, the early instars of all three species displayed a pronounced polygonal reticulation, a net-like pattern of ridges covering the valve surface that included hexagonal and other irregular shapes. As the animals molted toward adulthood, this ornamentation progressively weakened and eventually disappeared entirely. This matters enormously for taxonomy: a fossilized juvenile shell with strong reticulation could easily be misidentified as a different species if researchers did not know that ornamentation fades with age. The study demonstrates that valve ornamentation alone is not a reliable taxonomic character, but becomes highly informative when evaluated in relation to developmental stage.

The eggs themselves proved equally revealing. All three species produce ellipsoidal eggs with a two-layered eggshell, an inner layer produced by the oocyte and an outer layer secreted by the ovarian epithelium, a structure first described in classical histological studies over a century ago. Yet the eggs differed dramatically in size between species even under identical laboratory conditions: H. incongruens eggs averaged 147 micrometers in diameter, H. exodonta eggs 129 micrometers, and H. salina eggs just 91 micrometers. Since all three were raised in the same water, at the same temperature, and fed the same spinach, these differences must reflect intrinsic species-specific traits rather than environmental influences, making egg size a potentially powerful diagnostic character.

The survival machinery packed into these eggs is extraordinary. Resting eggs of Heterocypris are known to withstand desiccation and extreme temperatures ranging from minus 18 to 42 degrees Celsius, and can remain viable in a dormant state for more than 20 years. In the study, eggs of H. exodonta were deliberately dried for 120 hours, causing them to collapse, yet after rehydration they turned orange within 20 minutes and regained their original diameter within an hour. This resilience underpins the formation of so-called egg banks, accumulations of viable dormant eggs in sediment that hatch when conditions turn favorable, acting as ecological reservoirs that allow populations to persist in ephemeral ponds that dry out seasonally and recolonize after disturbance.

The research also tested a venerable rule of crustacean biology. Brooks’ rule, proposed in 1886, holds that arthropods roughly double their volume with each molt, which translates into a linear size increase of about 1.26 per stage. The measured growth ratios in all three Heterocypris species converged on values close to this prediction, ranging from about 1.21 to 1.26 for valve length and height. But the averages concealed considerable variation among species and stages, with larger increments in intermediate instars and smaller ones in the final molts, possibly linked to the development of reproductive structures at maturity. The authors conclude that geometric growth represents a general tendency rather than a fixed rule, and that growth ratios alone cannot reliably distinguish closely related species.

Raising the animals was not without its challenges. The researchers found that newly hatched A-8 juveniles kept in isolation died within 7 to 9 days despite being fed, but when 10 to 15 juveniles shared a compartment, survival extended to 25 to 30 days and many reached adulthood. This aggregation behavior, likely tied to favorable water conditions and food access, also appeared to protect against fungal contamination. The complete life cycle from hatching to final molt took only about 35 to 60 days under laboratory conditions, though the team noted that development slows dramatically in winter, with juveniles apparently entering a dormant phase until warmed by sunlight.

The broader implications reach deep into paleoclimate science. Because ostracod valves are often the only part of the animal preserved in sediments, and because early juvenile stages calcify weakly and preserve poorly, sediment records are inherently biased toward adults and later instars. Understanding the full ontogenetic sequence allows researchers to distinguish genuine population structure from the effects of sediment transport, wind-driven hydrodynamics, and taphonomic loss. It also helps resolve a longstanding puzzle: whether widespread species like H. incongruens and H. salina are truly cosmopolitan or actually complexes of cryptic taxa, a question that molecular studies suggest is increasingly likely, with multiple clonal lineages already documented within these morphologically uniform animals.

Ultimately, the study delivers something the field has lacked for over a century: complete, high-resolution documentation of every developmental stage in three Heterocypris species, from the layered architecture of the eggshell to the fading reticulation of the growing valve. As lake sediments worldwide are interrogated for clues about monsoon dynamics, drought history, and ecosystem response to warming, these tiny crustaceans and their meticulously catalogued life stages will serve as indispensable benchmarks, ensuring that the stories locked in ancient mud are read with the precision they deserve.

Subject of Research: Ontogenetic development, egg morphology, and valve growth of three cultured freshwater ostracod species of the genus Heterocypris

Article Title: Ontogenetic growth of three cultured species of Heterocypris Claus, 1892 (Crustacea: Ostracoda): eggs and valve morphology

Article References: Bonilla-Flores, M., Pérez, L., Frenzel, P., Echeverría-Galindo, P., Wang, J., & Schwalb, A. (2026). Ontogenetic growth of three cultured species of Heterocypris Claus, 1892 (Crustacea: Ostracoda): eggs and valve morphology. Journal of Micropalaeontology, 45(1), 429-453. https://doi.org/10.5194/jm-45-429-2026

Image Credits: AI Generated

DOI: 10.5194/jm-45-429-2026

Keywords: ostracods, Heterocypris, ontogeny, valve morphology, egg banks, Brooks' rule, paleoecology, Tibetan Plateau, laboratory culture, scanning electron microscopy, crustaceans, lake sediments

A team of researchers led by Bi Irie Ghislain Tré of Nangui Abrogoua University, working with colleagues in Côte d’Ivoire and France, measured 550 mahogany trees across three natural stands spanning the country’s major agro-ecological zones. The sites could hardly be more different in character. Pouniakele, in the northern Sudanian savanna, receives about 1,200 millimetres of rain a year and is the driest and most disturbed of the three, with pastures and agricultural exploitation pressing in on the trees. Kouassi-N’Dawa, in the east, is a sacred forest on a hill where human activity is deliberately limited by cultural tradition. Koumokro, in the centre-east, is a community forest sitting in the climatic transition zone between subtropical and humid tropical conditions, receiving roughly 1,300 millimetres of annual rainfall. Measurements were collected between January 2022 and June 2024, all on standing trees in their natural habitat, using non-destructive techniques.

The methodological design is what gives the study its power. Rather than treating all trees as a single population, the researchers sorted them into three diameter-based cohorts that serve as proxies for developmental stages: young trees between 5 and 25 centimetres in diameter, non-exploitable adults from 25 to 40 centimetres, and exploitable adults of 40 centimetres or more, the size class targeted by selective cutting for charcoal. On every tree, eleven traits were recorded, ranging from the classic dendrometric measures of trunk diameter, total height, bole height and crown spread to a suite of foliar characters including leaf length and width, petiole length, the number of leaflets per leaf, and the length and width of individual leaflets. This dual focus on architecture and foliage allowed the team to track how different parts of the tree’s form respond to different pressures across the lifespan.

The statistical treatment was equally rigorous. After standardisation, the data were subjected to analysis of variance to detect differences among sites within each cohort, then to hierarchical cluster analysis to group trees with similar morphology, and finally to discriminant function analysis to identify which traits did the best job of separating those groups. Bartlett’s test of sphericity and the Kaiser-Meyer-Olkin measure confirmed the datasets were suitable for multivariate work. The results were strikingly consistent: at every developmental stage, and again when all 550 trees were pooled, the analyses resolved three distinct morphological groups, and leaf length and leaflet length emerged as the most discriminating traits across all stages of life.

Some of the site-level patterns were unexpected. Pouniakele, despite being the driest and most degraded site, produced trees with the largest mean diameters in every cohort. Kouassi-N’Dawa and Koumokro, by contrast, yielded trees with significantly larger leaves. In the young cohort, ten of the eleven measured variables differed highly significantly among sites, with juveniles at Kouassi-N’Dawa reaching the greatest total heights, an apparent response to light competition in the shaded sacred forest. Among non-exploitable adults, Koumokro dominated seven variables, posting the tallest mean height at 13.54 metres and the widest crown spread at 8.5 metres, while Pouniakele trees paradoxically combined the thickest trunks, averaging 33.12 centimetres, with the lowest values for six other traits.

Perhaps the most intriguing result is a reversal in the ontogenetic trajectory of diameter. Among juveniles, the gradient ran from thickest at Koumokro to thinnest at Pouniakele. By maturity, that order had flipped, with Pouniakele trees topping the rankings. The researchers interpret this inversion as evidence that the survivors at the harsh northern site prioritise radial growth to enhance mechanical stability and resource storage after episodes of water stress and pruning. Supporting this reading, the coefficient of variation for crown spread surged from 25.6 percent in young trees to 51.9 percent in exploitable adults, a signature of individual trees each following their own adaptive path through a mosaic of microhabitats and human disturbances.

The pooled analysis of all trees crystallised the picture into three site-scale morphotypes. Group 1 contained the giants of the sample, with a mean diameter of 42.9 centimetres, a total height of 14.37 metres and a crown spread of 9.53 metres, but the shortest leaves at 28.3 centimetres. Group 3 sat at the opposite pole: small trees averaging just 10 centimetres in diameter and 6.6 metres in height, yet bearing the largest leaves, up to 37.7 centimetres long. The geographic distribution of these morphotypes was anything but random. At drought-prone Pouniakele, 60.5 percent of trees belonged to the big-trunk, small-leaf Group 1, a combination that favours water conservation and mechanical resilience. At Kouassi-N’Dawa and Koumokro, where regeneration is denser and competition for light fiercer, the small-stature, large-leaf Group 3 dominated, reflecting an investment in foliar area to fuel rapid height growth in crowded stands. At Pouniakele, that morphotype was almost entirely absent, accounting for just 1.2 percent of trees.

The study’s two founding hypotheses fared differently. The first, that morphological heterogeneity would be greatest at the juvenile stage, was confirmed: coefficients of variation showed young trees to be the most variable, consistent with high initial phenotypic plasticity. The second, that natural selection would progressively filter this diversity into a converged adult form, was refuted. Even the exploitable adults remained strongly differentiated, with seven of eleven parameters differing significantly among sites. This persistence of structure into old age suggests that savanna mahogany maintains multiple viable adaptive strategies simultaneously rather than marching toward a single optimal body plan. The authors frame this as an evolutionary bet-hedging strategy, a reservoir of resilience against environmental fluctuation, though they caution that the coexistence of several phenotypic groups could also represent a transitional phase before a stable adaptive optimum emerges under recurrent disturbances such as bushfires and pruning.

The practical implications reach well beyond evolutionary theory. Because leaf length and leaflet length proved reliably discriminant at every stage, foresters now have simple, measurable phenotypic criteria for selecting superior mother trees for seed collection, a critical step for plantation development that could relieve pressure on natural stands. The identification of vulnerable growth stages also helps target protection efforts. At the same time, the authors are candid about the limits of their work. The study relies exclusively on morphology, so it cannot yet say whether the observed morphotypes reflect genetic differentiation between populations or purely environmental plasticity, and the cohort design compares different individuals rather than following the same trees over time. Combining the morphometric approach with neutral genetic markers, and mounting long-term monitoring of marked cohorts, are the obvious next steps. What is already clear, however, is that conserving this species means conserving its diversity of forms, not just its count of individuals, and that a sacred forest, a community woodland and a battered northern savanna each preserve a different chapter of the mahogany’s adaptive story.

Subject of Research: Ontogenetic variation in morphological traits of Khaya senegalensis across three savanna sites in Côte d'Ivoire

Article Title: Ontogenic dynamics of phenotypic diversity in savanna mahogany (Khaya senegalensis) across three sites in Côte d’Ivoire

Article References: Tré, B. I. G., Koffi, K. G., Kouonon, L.-C., Yao, Y. E. P., Pereda-Loth, V., & Sié, R. S. (2026). Ontogenic dynamics of phenotypic diversity in savanna mahogany (Khaya senegalensis) across three sites in Côte d’Ivoire. Discover Plants, 3(1), Article 408. https://doi.org/10.1007/s44372-026-00883-8

Image Credits: AI Generated

DOI: 10.1007/s44372-026-00883-8

Keywords: Khaya senegalensis, savanna mahogany, phenotypic plasticity, ontogeny, Côte d'Ivoire, morphological variability, tree conservation, CITES, mother tree selection, drought adaptation, leaf morphology, sustainable forestry

The research was conducted by C. Garcia-Co, A. Dewulf, F. Verbruggen, J. Morales and W. Müller, working across the University of Antwerp, Ghent University and the Spanish National Research Council. The team took advantage of a well-characterised lab-bred population of domestic canaries (Serinus canaria), a species in which maternal aggression toward nestlings varies noticeably between females. Because the birds were kept under controlled, semi-natural conditions, the researchers could observe maternal behaviour at the nest directly, define each mother’s aggression phenotype through careful observation, and then measure cognition in both mothers and offspring using standardised behavioural assays. This combination of ecological realism and experimental control is rare, and it is precisely what made the study capable of addressing the transmission question head-on.

Inhibitory control was assessed with a detour task, one of the most widely used benchmarks of self-regulation in comparative psychology. In this task, an animal can see a reward through a transparent barrier but cannot reach it directly; success requires suppressing the instinctive, straight-line approach and instead taking an indirect route around the obstacle. The task sounds simple, yet it reliably separates individuals: those with stronger response inhibition tend to solve the detour quickly, while those prone to impulsive approach repeatedly bump into the barrier. Detour performance has been linked to a range of ecological and social traits across species, which is exactly why the canary team expected that mothers differing in aggression might also differ in how well they executed the task. The transparent-cylinder style detour used here forced each bird to inhibit a prepotent response in favour of a learned, circuitous solution.

The first key prediction concerned the mothers themselves. If maternal aggression reflected a failure of behavioural inhibition, then aggressive females should have performed worse on the detour task than their more tolerant counterparts. The data did not support this. When the researchers compared detour performance between aggressive and non-aggressive mothers, they found no meaningful differences in inhibitory control between the two groups. Aggressive mothers were neither slower to learn the detour nor more likely to make impulsive approach errors. In other words, in this population, striking a nestling does not appear to be the behavioural signature of a female who cannot inhibit her impulses. The cognitive-deficit hypothesis, at least in its simplest form, failed to find support in adult canaries.

The second and arguably more ambitious prediction concerned the offspring. Early-life stressors, including hostile social environments, are known in many species to leave lasting marks on behaviour and cognition, and some theoretical frameworks propose intergenerational transmission of such effects. The canary study asked two distinct questions: does growing up with an aggressive mother impair a juvenile’s later inhibitory control, and do offspring resemble their biological mothers in detour performance regardless of who raises them? To disentangle these possibilities, the team employed a cross-fostering design, in which chicks were swapped between nests so that some were raised by females other than their biological mothers. This elegant manipulation separates post-hatching environmental influences, such as exposure to maternal aggression, from prenatal and genetic contributions carried by the biological mother.

Once again, the results were unambiguous in their null finding. Juvenile inhibitory control was not influenced by post-hatching exposure to maternal aggression, nor was it predicted by the aggression phenotype of the biological mother. Moreover, the researchers detected no mother–offspring covariation in inhibitory control: daughters and sons did not systematically resemble either the foster mothers who raised them or the biological mothers who produced them in this cognitive measure. Taken together, these findings suggest that maternal aggression in canaries is unlikely to be transmitted across generations through the pathway of inhibitory control, and that the cognitive trait measured by the detour task is not a heritable or environmentally transmitted correlate of aggressive parenting in this system.

Amid all the null results, the study did uncover something striking: powerful ontogenetic effects. Juvenile canaries took substantially longer to complete the detour than adults, but they improved more steeply across trials, a pattern consistent with a post-hatching maturation of inhibitory control. In other words, young birds start out impulsive and slow to suppress the direct approach, but with experience and development their self-regulation improves rapidly. This developmental trajectory is itself scientifically important. It demonstrates that inhibitory control, as measured by the detour task, is not a fixed trait but a capacity that changes markedly with age in canaries, echoing findings from a broad range of vertebrates in which response inhibition continues to mature well after fledging or weaning.

The authors argue that their findings carry a broader methodological lesson for the field of comparative cognition. Inhibitory control measures are notoriously task- and context-specific: an individual that performs poorly on one inhibition assay may excel on another, and performance can be swayed by motivation, neophobia, motor capacity and prior experience. The absence of a link between maternal aggression and detour performance in canaries does not necessarily mean that no cognitive difference exists between aggressive and tolerant mothers; it may mean that the detour task captures only one facet of a multidimensional construct. The study therefore serves as a caution against overinterpreting single-task measures and against building sweeping theories of behavioural syndromes on the basis of one assay in one context.

The research also speaks to a long-running debate in behavioural ecology about the origins and persistence of harmful parental behaviour. Maternal aggression toward offspring represents an early-life social stressor that has been linked to long-term behavioural differences in several species, making its underlying mechanisms a matter of genuine scientific and welfare interest. By showing that this aggression is unlikely to reflect deficits in inhibitory control, and equally unlikely to be transmitted to offspring via that cognitive route, the canary study narrows the space of plausible explanations. Future work may need to explore alternative mechanisms, including hormonal states, stress physiology, neural circuits of social behaviour, or entirely different cognitive dimensions. The study was approved by the ethics committees of the University of Antwerp and Ghent University, and the birds remain part of an ongoing transgenerational transmission experiment, meaning this carefully bred population may yet reveal what does and does not pass from mother to chick. For now, the message is a refreshing dose of rigour: a plausible and popular hypothesis, tested thoroughly, simply did not hold up, and science is stronger for knowing it.

Subject of Research: The relationship between maternal aggression and inhibitory control, and its potential intergenerational transmission, in domestic canaries.

Article Title: No evidence for a link between maternal aggression and inhibitory control across generations in domestic canaries

Article References: Garcia-Co, C., Dewulf, A., Verbruggen, F., Morales, J., & Müller, W. (2026). No evidence for a link between maternal aggression and inhibitory control across generations in domestic canaries. Animal Cognition. https://doi.org/10.1007/s10071-026-02110-z

Image Credits: AI Generated

DOI: 10.1007/s10071-026-02110-z

Keywords: inhibitory control, maternal aggression, detour task, domestic canaries, animal cognition, cross-fostering, transgenerational transmission, response inhibition, ontogeny, behavioral ecology, early-life stress, Serinus canaria

The research, conducted in Páramo Grande within the Chingaza complex in Cundinamarca, Colombia, tracked leaf water potential and gas exchange in ten tagged individuals, five juveniles and five adults, across the wet season from September to December 2023 and the dry season from January to February 2024. Adults were defined as rosettes at least 25 centimeters in diameter with inflorescences or peduncle traces, while juveniles were 15 centimeters or smaller and lacked reproductive structures. The team measured midday leaf water potential with a pressure chamber and morning gas exchange, including stomatal conductance, transpiration, and net carbon dioxide assimilation, using a portable photosynthesis system, alongside detailed microclimate recordings.

The seasonal contrast was dramatic. Soil water content averaged 73.8 percent during the wet season but collapsed to 21.9 percent in the dry season, while relative humidity fell from 72.8 to 56.3 percent and mean air temperature climbed from 15.9 to 19.8 degrees Celsius. The leaf-to-air vapor pressure deficit, or VPD, a key driver of water loss, rose from around 1.3 kilopascals in the wet season to a maximum of 3.2 kilopascals in February. These shifts in the physical environment translated directly into plant stress: leaf water potential declined sharply in both stages during the dry months, with juveniles reaching approximately minus 2.7 megapascals in January compared with minus 1.8 megapascals in adults, a statistically significant difference.

That juvenile dehydration reflects a deeper physiological strategy. During the wet season, juveniles consistently opened their stomata wider than adults, with stomatal conductance peaking at 171 millimoles per square meter per second in December, while adults remained below 100 throughout the study. Juveniles also transpired at higher and more stable rates when water was abundant. Yet this aggressive gas exchange came at a cost: when the dry season arrived and atmospheric demand surged, juveniles proved more vulnerable, dropping to significantly lower water potentials and closing their stomata almost completely, with conductance falling below 10 millimoles per square meter per second in both stages by February.

Carbon gain told a different story. Despite the juveniles’ higher conductance and transpiration, net carbon dioxide assimilation varied primarily with season rather than developmental stage. Assimilation peaked during the wet season, reaching maximum rates of about 6 micromoles per square meter per second in adults and slightly above 4 in juveniles in October, then fell below 2 micromoles per square meter per second in both stages by February. Light response curves showed a photosynthetic saturation point near 500 micromoles per square meter per second, with a light compensation point of roughly 24 micromoles of photons and a respiration rate averaging about 0.2 micromoles of carbon dioxide per square meter per second.

The most striking technical finding is the tight hydraulic-stomatal coupling that governs the species. Across all sampling dates, stomatal conductance was inversely related to VPD, following a power-law relationship that explained roughly two-thirds of the variance. When the atmosphere pulled harder on leaf water, stomata closed; when demand eased, they opened. This regulation minimizes water loss at the expense of carbon assimilation under dry conditions, a classic trade-off in water-limited environments, but here it operates with stage-specific intensity.

Why would juveniles run riskier water budgets than adults? The authors point to ontogeny: differences in whole-plant hydraulic architecture, rooting depth, biomass allocation, and leaf functional traits that shift as plants mature. Adults likely benefit from greater hydraulic capacitance and more developed root systems, buffering their water relations and allowing a more conservative stomatal posture. Juveniles, smaller and closer to the ground where near-surface microclimates swing more extreme, appear to follow an opportunistic strategy, maximizing carbon gain when conditions permit but absorbing greater hydraulic risk when they do not. The researchers also note that because all adults in the study were reproductive, some of the observed differences may reflect reproductive investment as well as ontogenetic effects.

The comparison with other páramo rosettes adds nuance. In the caulescent giant rosette Coespeletia moritziana, juveniles similarly showed stronger stomatal closure and greater reductions in assimilation during drought. But in some Colombian páramo species studied previously, assimilation actually increased during the dry season, apparently because persistent wet-season cloudiness, rather than water limitation, constrains carbon gain in those systems. Paepalanthus alpinus bucks that pattern, suggesting that growth form matters: low, acaulescent rosettes may be more sensitive to dry-season soil and atmospheric water stress than taller species that ride above the boundary layer.

The implications stretch beyond one species. Global assessments show that VPD has already increased in recent decades and is projected to keep rising as warming outpaces changes in relative humidity, and elevated VPD is known to suppress stomatal conductance and photosynthesis worldwide. Regional projections for the tropical Andes point to robust warming with heterogeneous, and in some northern sectors decreasing, precipitation. For a species whose juveniles already sit at the physiological edge during the dry season, these trends could disproportionately hit early life stages, reducing recruitment and threatening long-term population stability. Microsites that buffer atmospheric demand, such as shaded areas, moist depressions, and soils rich in organic matter, may become critical refugia for juvenile survival.

The study, published open access in Discover Plants, underscores a broader conservation message: preserving the full diversity of microhabitats within páramo landscapes is essential for endemic species like P. alpinus. Understanding physiological thresholds across growth stages, the authors argue, is essential for predicting species resilience and informing management strategies in one of the world’s most important alpine biodiversity hotspots, an ecosystem that also supplies water to millions of people downstream.

Subject of Research: Ontogenetic variation in water relations and gas exchange of the páramo rosette Paepalanthus alpinus in the tropical high Andes

Article Title: Water relations and gas exchange across developmental stages in the páramo rosette Paepalanthus alpinus Körn. (Eriocaulaceae) in the tropical high Andes

Article References: Water relations and gas exchange across developmental stages in the páramo rosette Paepalanthus alpinus Körn. (Eriocaulaceae) in the tropical high Andes. (n.d.). https://doi.org/10.1007/s44372-026-00829-0

Image Credits: AI Generated

DOI: 10.1007/s44372-026-00829-0

Keywords: Paepalanthus alpinus, páramo, tropical alpine, stomatal conductance, vapor pressure deficit, leaf water potential, ontogeny, gas exchange, hydraulic-stomatal coupling, Chingaza, drought stress, plant ecophysiology