Amphistomy: stomata patterning inferred from 13C content and leaf-side specific deposition of epicuticular wax.

BACKGROUND AND AIMS: The benefits and costs of amphistomy (AS) vs. hypostomy (HS) are not fully understood. Here, we quantify benefits of access of CO2 through stomata on the upper (adaxial) leaf surface, using 13C abundance in the adaxial and abaxial epicuticular wax. Additionally, a relationship between the distribution of stomata and epicuticular wax (EW) on the opposite leaf sides is studied. METHODS: We suggest that the 13C content of long-chain aliphatic compounds of cuticular wax records the leaf internal CO2 concentration in chloroplasts adjacent to the adaxial and abaxial epidermes. This unique property stems from (i) wax synthesis being located exclusively in epidermal cells and (ii) ongoing wax renewal over the whole leaf lifespan. Compound-specific and bulk wax 13C abundance (δ) was related to amphistomy level (ASL, fraction of adaxial in all stomata) of four AS and five HS species grown under various levels of irradiance. The isotopic polarity of EW, i.e. the difference in abaxial and adaxial δ(δab-δad), was used to calculate the leaf dorsi-ventral CO2 gradient. Leaf-side specific EW deposition, amphiwaxy level (AWL), was estimated and related to ASL. KEY RESULTS: In HS species, the CO2 concentration in the adaxial epidermis was lower than in the abaxial one independently of light conditions. In high-light and low-light grown AS leaves, the isotopic polarity and CO2 gradient varied in parallel with ASL. AS leaves grown under high light increased ASL compared to low light, and δab-δad approached near-zero values. Changes in ASL occurred concomitantly with changes in AWL. CONCLUSIONS: The leaf wax isotopic polarity is a newly identified leaf trait, distinguishing between hypo- and amphistomatous species and indicating that increased ASL in sun-exposed AS leaves reduces the CO2 gradient across the leaf mesophyll. Stomata and epicuticular wax deposition follow similar leaf-side patterning.

Testosterone and Erythrocyte Lifespan.

CONTEXT: Endogenous and exogenous androgens increase circulating erythrocytes and hemoglobin but their effects on erythrocyte lifespan is not known. OBJECTIVE: To investigate androgen effects on immature and mature erythrocyte lifespan in humans and mice using novel non-radioactive minimally invasive methods. DESIGN: Human erythrocyte lifespan was estimated using alveolar carbon monoxide concentration and blood hemoglobin in Levitt's formula in hypogonadal or transgender men before and up to 18 weeks after commencing testosterone (T) treatment. Erythrocyte lifespan was estimated in androgen receptor (AR) knockout and wild-type mice after T or dihydrotestosterone (DHT) treatment of intact females or orchidectomized males using in vivo biotin labelling of erythrocyte surface epitopes for reticulocytes (Ter119+CD71+) and two markers of erythrocytes (CD45-, Ter119+CD71-) monitoring their blood disappearance rate by flow cytometry. RESULTS: Before treatment, hypogonadal and transgender men had marked reduction in erythrocyte lifespan compared with controls. T treatment increased erythrocyte lifespan at 6 weeks but returned to pre-treatment levels at 18 weeks while serum T and blood hemoglobin were increased by T treatment remaining elevated at 18-weeks. In mice T and DHT treatment had higher erythrocyte (but not reticulocyte) lifespan but neither orchidectomy nor AR inactivation significantly influenced erythrocyte or reticulocyte lifespan. CONCLUSIONS: We conclude that hypogonadal men have reduced erythrocyte lifespan and acute androgen-induced increase in circulating erythrocyte lifespan may contribute to the well-known erythropoietic effects of androgens, but longer-term effects require further investigation to determine how much they contribute to androgen-induced increases in circulating hemoglobin.

Teriparatide as Treatment for Severe Osteoporosis in Lung Transplant Recipients.

Osteoporosis and osteopenia are common in lung transplant (LTx) recipients, with a significantly increased incidence compared to other non-lung solid organ transplant patients. Despite high fracture rates, including in patients treated with antiresorptive medications, there are limited data on the use of anabolic treatments in LTx recipients. We present clinical, biochemical and bone mineral density data for 3 patients with severe osteoporosis treated with teriparatide 20 micrograms daily for 18 months post-LTx. Prednisone doses ranged between 5 and 10 mg daily throughout the treatment period. All patients had previously received zoledronate (last dose 12-24 months prior to teriparatide). Bone turnover was monitored repeatedly during treatment in one patient. Following completion of teriparatide, all patients received consolidation treatment with 4 mg zoledronate. Bone density was measured prior and within 6 to 12 months after completion of teriparatide. All 3 patients experienced an increase in bone density at the lumbar spine (median +12%; range, 2%-14%) and total proximal femur (median +8%, range, 8%-10%). No adverse effects were observed. Given that severe osteoporosis is highly prevalent in LTx patients, teriparatide should be further studied as a treatment in this clinical setting. Our cases suggest it is safe and effective.

Effects of gender affirming hormone treatment in transgender individuals - a retrospective cohort study.

PURPOSE: Gender affirming hormone treatment (GAHT) results in measurable changes to anthropomorphic, biochemical and hormonal variables that are important to patients and their health care professionals to guide treatment. This study sought to quantify changes which occur in response to initiation of GAHT. METHODS: We performed a retrospective cohort study of outcomes in transgender and gender diverse (TGD) patients starting GAHT. The primary outcome was proportion of patients and time required to achieve optimal hormone levels after commencement of GAHT. Additional analyses were performed to assess whether clinical and biochemical factors were associated with likelihood of achieving target hormone levels. RESULTS: 345 patients were included. Among 154 transmasculine individuals, 116 (75%) achieved a testosterone level >10 nmol/L during follow-up at a median of 4-months (IQR 4-9). No clinical or biochemical factors were significantly associated with likelihood of reaching therapeutic testosterone concentrations in transmen. Among 191 transfeminine individuals, 131 (72%) achieved a testosterone level <2.0 nmol/L during follow-up at a median of 4-months (IQR 3-9). Factors associated with increased likelihood of testosterone suppression were use of subdermal estradiol implants as well as cyproterone acetate as an androgen antagonist. Changes in differing directions were observed during repeated measures of lipids, liver function, and blood count between transmasculine and transfeminine individuals, reflecting the important effects of testosterone and estradiol on biochemical tests ordered as part of routine clinical care. CONCLUSION: Most TGD patients achieve target testosterone levels within 9 months of GAHT initiation. Adverse effects of GAHT are rare, and are usually mild.

Amphistomy increases leaf photosynthesis more in coastal than montane plants of Hawaiian 'ilima (Sida fallax).

PREMISE: The adaptive significance of amphistomy (stomata on both upper and lower leaf surfaces) is unresolved. A widespread association between amphistomy and open, sunny habitats suggests the adaptive benefit of amphistomy may be greatest in these contexts, but this hypothesis has not been tested experimentally. Understanding amphistomy informs its potential as a target for crop improvement and paleoenvironment reconstruction. METHODS: We developed a method to quantify "amphistomy advantage" ( AA $\text{AA}$ ) as the log-ratio of photosynthesis in an amphistomatous leaf to that of the same leaf but with gas exchange blocked through the upper surface (pseudohypostomy). Humidity modulated stomatal conductance and thus enabled comparing photosynthesis at the same total stomatal conductance. We estimated AA $\text{AA}$ and leaf traits in six coastal (open, sunny) and six montane (closed, shaded) populations of the indigenous Hawaiian species 'ilima (Sida fallax). RESULTS: Coastal 'ilima leaves benefit 4.04 times more from amphistomy than montane leaves. Evidence was equivocal with respect to two hypotheses: (1) that coastal leaves benefit more because they are thicker and have lower CO2 conductance through the internal airspace and (2) that they benefit more because they have similar conductance on each surface, as opposed to most conductance being through the lower surface. CONCLUSIONS: This is the first direct experimental evidence that amphistomy increases photosynthesis, consistent with the hypothesis that parallel pathways through upper and lower mesophyll increase CO2 supply to chloroplasts. The prevalence of amphistomatous leaves in open, sunny habitats can partially be explained by the increased benefit of amphistomy in "sun" leaves, but the mechanistic basis remains uncertain.

Early post-transplant hyperglycemia and post-transplant diabetes mellitus following heart transplantation.

INTRODUCTION: Heart transplantation is an important treatment for end-stage heart failure. Early post-transplant hyperglycemia (EPTH) and post-transplant diabetes mellitus (PTDM) are common following heart transplantation and are associated with increased morbidity and mortality. AREAS COVERED: This review summarizes the clinical characteristics, diagnosis, and treatment of EPTH and PTDM in cardiac transplant patients, incorporating findings from non-cardiac solid organ transplant studies where relevant due to limited heart-specific research. EXPERT OPINION: EPTH following heart transplantation is common yet understudied and is associated with the later development of PTDM. PTDM is associated with adverse outcomes including infection, renal dysfunction, microvascular disease, and an increased risk of re-transplantation and mortality. Risk factors for EPTH include the post-operative immunosuppression regimen, recipient and donor age, body mass index, infections, and chronic inflammation. Early insulin treatment is recommended for EPTH, whereas PTDM management is varied and includes lifestyle modification, anti-glycemic agents, and insulin. Given the emerging evidence on the transplant benefits associated with effective glucose control, and the cardioprotective potential of newer anti-glycemic agents, further focus on the management of EPTH and PTDM within heart transplant recipients is imperative.

Glucagon-like Peptide-1 Receptor Agonist Treatment With Semaglutide in Type 1 Diabetes.

The efficacy of glucagon-like peptide-1 receptor agonists in type 2 diabetes is well established, but their role in type 1 diabetes (T1DM) is less clear. A 36-year-old woman with a 27-year history of T1DM and undetectable c-peptide presented for review of weight management, with body mass index 29.3 kg/m2. A previous trial of dapagliflozin led to no improvement in weight or glycemic control. Semaglutide was introduced (0.25 mg weekly increased to 0.5 mg weekly) and was well tolerated. After 6 months, weight had decreased by 16 kg and insulin dose by 36%. Despite less insulin, hemoglobin A1c improved, with reduced glycemic variability and no increase in hypoglycemia. Semaglutide may exert significant metabolic benefits in patients with established T1DM, even where c-peptide is no longer detectable. This case supports the need for a dedicated trial examining potential benefits of semaglutide in T1DM.

Diagnosis and management of prolactin-secreting pituitary adenomas: a Pituitary Society international Consensus Statement.

This Consensus Statement from an international, multidisciplinary workshop sponsored by the Pituitary Society offers evidence-based graded consensus recommendations and key summary points for clinical practice on the diagnosis and management of prolactinomas. Epidemiology and pathogenesis, clinical presentation of disordered pituitary hormone secretion, assessment of hyperprolactinaemia and biochemical evaluation, optimal use of imaging strategies and disease-related complications are addressed. In-depth discussions present the latest evidence on treatment of prolactinoma, including efficacy, adverse effects and options for withdrawal of dopamine agonist therapy, as well as indications for surgery, preoperative medical therapy and radiation therapy. Management of prolactinoma in special situations is discussed, including cystic lesions, mixed growth hormone-secreting and prolactin-secreting adenomas and giant and aggressive prolactinomas. Furthermore, considerations for pregnancy and fertility are outlined, as well as management of prolactinomas in children and adolescents, patients with an underlying psychiatric disorder, postmenopausal women, transgender individuals and patients with chronic kidney disease. The workshop concluded that, although treatment resistance is rare, there is a need for additional therapeutic options to address clinical challenges in treating these patients and a need to facilitate international registries to enable risk stratification and optimization of therapeutic strategies.

Metabolic Sequelae of Everolimus Treatment After Cardiac Transplant: A Hypothesis-Generating Study.

BACKGROUND: Although modern immunosuppressants improve survival post-transplant, they are associated with long-term metabolic complications, such as post-transplant diabetes mellitus (PTDM). Calcineurin inhibitor-sparing regimens using everolimus attenuate some complications such as left ventricular hypertrophy. However, the metabolic effects of everolimus following transplant are less clear. METHODS: Post-hoc analysis to compare PTDM and other metabolic outcomes in participants of a randomised open-label clinical trial of low-dose everolimus and tacrolimus versus standard-dose tacrolimus in heart transplant recipients (RADTAC1 study). RESULTS: There were 39 participants in the trial; mean follow-up was 6.4±1.5 years. There was a high rate of pre-existing diabetes (26%) and newly diagnosed PTDM (36%) during follow-up. Half the patients who developed PTDM in the everolimus-tacrolimus group (n=4/8) ceased diabetes medications during follow-up, which was not observed in patients on standard tacrolimus (n=0/6). In the first 12 months there was a higher use of non-insulin treatment for diabetes in the everolimus-tacrolimus group compared to the standard tacrolimus group. CONCLUSIONS: This study suggests that treatment with everolimus may be associated with improved glycaemic control of PTDM relative to treatment with standard doses of calcineurin inhibitor. These findings should be further studied in prospective randomised trials.

How Important Are Functional and Developmental Constraints on Phenotypic Evolution? An Empirical Test with the Stomatal Anatomy of Flowering Plants.

AbstractQuantifying the relative contribution of functional and developmental constraints on phenotypic variation is a long-standing goal of macroevolution, but it is often difficult to distinguish different types of constraints. Alternatively, selection can limit phenotypic (co)variation if some trait combinations are generally maladaptive. The anatomy of leaves with stomata on both surfaces (amphistomatous) present a unique opportunity to test the importance of functional and developmental constraints on phenotypic evolution. The key insight is that stomata on each leaf surface encounter the same functional and developmental constraints but potentially different selective pressures because of leaf asymmetry in light capture, gas exchange, and other features. Independent evolution of stomatal traits on each surface imply that functional and developmental constraints alone likely do not explain trait covariance. Packing limits on how many stomata can fit into a finite epidermis and cell size-mediated developmental integration are hypothesized to constrain variation in stomatal anatomy. The simple geometry of the planar leaf surface and knowledge of stomatal development make it possible to derive equations for phenotypic (co)variance caused by these constraints and compare them with data. We analyzed evolutionary covariance between stomatal density and length in amphistomatous leaves from 236 phylogenetically independent contrasts using a robust Bayesian model. Stomatal anatomy on each surface diverges partially independently, meaning that packing limits and developmental integration are not sufficient to explain phenotypic (co)variation. Hence, (co)variation in ecologically important traits like stomata arises in part because there is a limited range of evolutionary optima. We show how it is possible to evaluate the contribution of different constraints by deriving expected patterns of (co)variance and testing them using similar but separate tissues, organs, or sexes.

Sodium glucose co-transporter 2 inhibition with empagliflozin on metabolic, cardiac and renal outcomes in recent cardiac transplant recipients (EMPA-HTx): protocol for a randomised controlled trial.

INTRODUCTION: Cardiac transplantation (CTx) is a life-saving operation that can improve the quality and length of a recipient's life. Immunosuppression medication, required to prevent rejection, can result in adverse metabolic and renal effects. Clinically significant complications include metabolic effects such as diabetes and weight gain, renal impairment, and cardiac disease such as allograft vasculopathy and myocardial fibrosis. Sodium glucose co-transporter 2 (SGLT2) inhibitors are a class of oral medication that increase urinary excretion of glucose. In patients with type 2 diabetes, SGLT2 inhibitors improve cardiovascular, metabolic and renal outcomes. Similar benefits have been shown in patients with heart failure and reduced ejection fraction irrespective of diabetes status. In patients with post-transplant diabetes mellitus, SGLT2 inhibitors improve metabolic parameters; however, their benefit and safety have not been evaluated in randomised prospective studies. This study will potentially provide a novel therapy to improve or prevent complications (diabetes, kidney failure and heart fibrosis) that occur with immunosuppressive medications. METHODS: The EMPA-HTx study is a randomised, placebo-controlled trial of the SGLT2 inhibitor empagliflozin 10 mg daily versus placebo in recent CTx recipients. One hundred participants will be randomised 1:1 and commence the study medication within 6-8 weeks of transplantation with treatment and follow-up until 12 months after transplantation. Demographic information, anthropomorphic measurements, pathology tests and cardiac magnetic resonance (CMR) scan will be recorded at baseline and follow-up. Patients will be reviewed monthly during the study until 12 months post-CTx and data will be collected for each patient at each study visit. The overall aim of the study is to assess the safety and efficacy of empagliflozin in CTx recipients. The primary outcome is glycaemic improvement measured as change in glycated haemoglobin and/or fructosamine. Key secondary outcomes are cardiac interstitial fibrosis measured by CMR and renal function measured by estimated glomerular filtration rate. ETHICS AND DISSEMINATION: This study has been approved by St Vincent's Hospital Human Research Ethics Committee (2021/ETH12184). The findings will be presented at national and international scientific meetings and published in peer-reviewed journals. TRIAL REGISTRATION NUMBER: ACTRN12622000978763.

Technical comment on "Negative-assortative mating for color in wolves".

Hedrick et al. (2016) (Negative-assortative mating for color in wolves. Evolution, 70, 757-766) reported on "negative-assortative mating for color in wolves" from Yellowstone National Park, the "first documented case of significant negative-assortative mating in mammals." Here I report a logical inconsistency in their population genetic model that effectively imposes selection against some assortatively mating genotype. After pointing out this inconsistency, I derive new expressions for the frequency of different matings and the equilibrium allele frequencies. Compared to Hedrick et al. (2016) (Negative-assortative mating for color in wolves. Evolution, 70, 757-766), the system rapidly approaches an equilibrium based on observed levels of negative-assortative mating in this population. Hence, the revised model may strengthen the case that assortative mating can maintain polymorphism and provides logically consistent results to inform the study of nonrandom mating in other organisms.

Diabetes medication following heart transplantation: a focus on novel cardioprotective therapies-a joint review from endocrinologists and cardiologists.

There is accumulating evidence that novel glucose-lowering agents infer potent cardiovascular and renal benefits. Therefore, it is imperative to reassess the management of post-transplant diabetes mellitus and consider the role of newer agents. With improved transplant-related survival and high prevalence of post-transplant diabetes, management of long-term complications such as diabetes are increasingly important. There are limited guidelines to assist in choice of appropriate agents after solid organ transplantation. Traditional therapies including insulin and sulfonylureas may still have a role; however, other agents should be considered prior. The evidence of novel glucose-lowering agents in post-transplant care is limited, and most studies have focused on kidney transplant recipients. While there are some parallels between renal and cardiac transplant recipients, the potential cardiovascular benefits, particularly on cardiac fibrosis are unique to cardiac transplantation. The treatment of diabetes, with a focus on additional cardiac and renal benefits, needs to be brought to the forefront of post-transplant care with incorporation of recent evidence outside of transplantation. The role for novel glucose-lowering agents in cardiac transplant recipients will be explored, with a summary of available evidence.

Selection on early survival does not explain germination rate clines in Mimulus cardinalis.

PREMISE: Many traits covary with environmental gradients to form phenotypic clines. While local adaptation to the environment can generate phenotypic clines, other nonadaptive processes may also. If local adaptation causes phenotypic clines, then the direction of genotypic selection on traits should shift from one end of the cline to the other. Traditionally, genotypic selection on non-Gaussian traits like germination rate have been hampered because it is challenging to measure their genetic variance. METHODS: Here we used quantitative genetics and reciprocal transplants to test whether a previously discovered cline in germination rate showed additional signatures of adaptation in the scarlet monkeyflower (Mimulus cardinalis). We measured genotypic and population level covariation between germination rate and early survival, a component of fitness. We developed a novel discrete log-normal model to estimate genetic variance in germination rate. RESULTS: Contrary to our adaptive hypothesis, we found no evidence that genetic variation in germination rate contributed to variation in early survival. Across populations, southern populations in both gardens germinated earlier and survived more. CONCLUSIONS: Southern populations have higher early survival but it is not caused by faster germination. This pattern is consistent with nonadaptive forces driving the phenotypic cline in germination rate, but future work will need to assess whether there is selection at other life stages. This statistical framework should help expand quantitative genetic analyses for other waiting-time traits.

Immune Related Adverse Events of the Thyroid - A Narrative Review.

Immune checkpoints are small molecules present on the cell surface of T-lymphocytes. They maintain self-tolerance and regulate the amplitude and duration of T-cell responses. Antagonism of immune checkpoints with monoclonal antibodies (immune checkpoint inhibitors) is a rapidly evolving field of anti-cancer immunotherapy and has become standard of care in management of many cancer subtypes. Immune checkpoint inhibition is an effective cancer treatment but can precipitate immune related adverse events (irAEs). Thyroid dysfunction is the most common endocrine irAE and can occur in up to 40% of treated patients. Both thyrotoxicosis and hypothyroidism occur. The clinical presentation and demographic associations of thyrotoxicosis compared to hypothyroidism suggest unique entities with different etiologies. Thyroid irAEs, particularly overt thyrotoxicosis, are associated with increased immune toxicity in other organ systems, but also with longer progression-free and overall survival. Polygenic risk scores using susceptibility loci associated with autoimmune thyroiditis predict development of checkpoint inhibitor associated irAEs, suggesting potentially shared mechanisms underpinning their development. Our review will provide an up-to-date summary of knowledge in the field of thyroid irAEs. Major focus will be directed toward pathogenesis (including genetic factors shared with autoimmune thyroid disease), demographic associations, clinical presentation and course, treatment, and the relationship with cancer outcomes.

Core arbuscular mycorrhizal fungi are predicted by their high abundance-occupancy relationship while host-specific taxa are rare and geographically structured.

Habitat restoration may depend on the recovery of plant microbial symbionts such as arbuscular mycorrhizal (AM) fungi, but this requires a better understanding of the rules that govern their community assembly. We examined the interactions of soil and host-associated AM fungal communities between remnant and restored patches of subtropical montane forests. While AM fungal richness did not differ between habitat types, community membership did and was influenced by geography, habitat and host. These differences were largely driven by rare host-specific AM fungi that displayed near-complete turnover between forest types, while core AM fungal taxa were highly abundant and ubiquitous. The bipartite networks in the remnant forest were more specialized and hosts more specific than in the restored forest. Host-associated AM fungal communities nested within soil communities in both habitats, but only significantly so in the restored forest. Our results provide evidence that restored and remnant forests harbour the same core fungal symbionts, while rare host-specific taxa differ, and that geography, host identity and taxonomic resolution strongly affect the observed distribution patterns of these fungi. We suggest that host-specific interactions with AM fungi, as well as spatial processes, should be explicitly considered to effectively re-establish target host and symbiont communities.

Association of Antithyroid Antibodies in Checkpoint Inhibitor-Associated Thyroid Immune-Related Adverse Events.

CONTEXT: The significance of thyroid peroxidase (TPOAb) and thyroglobulin antibody (TgAb) in the pathogenesis of thyroid immune-related adverse events (irAEs) is unknown. OBJECTIVE: To characterize the association of anti-thyroid antibodies with the development of thyroid immune related adverse events. METHODS: A retrospective cohort study was conducted of patients with melanoma receiving immune checkpoint inhibitor (ICI) treatment. TPOAb, TgAb, and interleukin-6 (IL-6) were measured retrospectively using tumor-banked samples at baseline and at time of diagnosis of a thyroid irAE. In euthyroid patients (without thyroid irAEs) measures were repeated 30 to 60 days after ICI commencement, which was similar to the median time to onset of thyroid irAEs in other patients. RESULTS: A total of 122 patients were included-31 remained euthyroid, 47 developed subclinical thyrotoxicosis, 37 developed overt thyrotoxicosis, and 7 developed overt hypothyroidism without preceding thyrotoxicosis. Baseline elevation of TPOAb or TgAb was present in 19 (16%) and 28 (23%) patients, respectively. Positive TPOAb or TgAb at baseline was 97% and 100% specific for eventual development of a thyroid irAE, respectively. During ICI treatment, overt thyrotoxicosis, but not other subtypes of thyroid irAE, was associated with statistically significant increases in the titer of TgAb and TPOAb. Baseline IL-6 levels were not associated with thyroid irAE onset but statistically significantly increased during treatment in patients who developed overt hypothyroidism. CONCLUSIONS: TPOAb and TgAb positivity at baseline was more prevalent in patients who developed thyroid irAEs. Statistically significant increases or new antibody positivity was observed in association with overt thyrotoxicosis. TPOAb and TgAb positivity or increases during ICI treatment may be a useful biomarker to identify patients at increased risk of thyroid irAEs, particularly overt thyrotoxicosis.

The acquisitive-conservative axis of leaf trait variation emerges even in homogeneous environments.

BACKGROUND AND AIMS: The acquisitive-conservative axis of plant ecological strategies results in a pattern of leaf trait covariation that captures the balance between leaf construction costs and plant growth potential. Studies evaluating trait covariation within species are scarcer, and have mostly dealt with variation in response to environmental gradients. Little work has been published on intraspecific patterns of leaf trait covariation in the absence of strong environmental variation. METHODS: We analysed covariation of four leaf functional traits [specific leaf area (SLA) leaf dry matter content (LDMC), force to tear (Ft) and leaf nitrogen content (Nm)] in six Poaceae and four Fabaceae species common in the dry Chaco forest of Central Argentina, growing in the field and in a common garden. We compared intraspecific covariation patterns (slopes, correlation and effect size) of leaf functional traits with global interspecific covariation patterns. Additionally, we checked for possible climatic and edaphic factors that could affect the intraspecific covariation pattern. KEY RESULTS: We found negative correlations for the LDMC-SLA, Ft-SLA, LDMC-Nm and Ft-Nm trait pairs. This intraspecific covariation pattern found both in the field and in the common garden and not explained by climatic or edaphic variation in the field follows the expected acquisitive-conservative axis. At the same time, we found quantitative differences in slopes among different species, and between these intraspecific patterns and the interspecific ones. Many of these differences seem to be idiosyncratic, but some appear consistent among species (e.g. all the intraspecific LDMC-SLA and LDMC-Nm slopes tend to be shallower than the global pattern). CONCLUSIONS: Our study indicates that the acquisitive-conservative leaf functional trait covariation pattern occurs at the intraspecific level even in the absence of relevant environmental variation in the field. This suggests a high degree of variation-covariation in leaf functional traits not driven by environmental variables.