Temperatura tijela u prirodi, mehanizmi termoregulacije i evolucija termalnih karakteristika u lacertidnih guštera

We discuss three aspects of the thermal biology of lacertid lizards. First, we provide an overview of the available data on field body temperatures (Tb), the thermal sensitivity of various performance functions and selected body temperatures in different species of lacertid lizards. We also briefly summarise information on the mechanisms of thermoregulation. Second, we discuss recent developments to estimate the »precision« of thermoregulation, and the contribution of distinct behavioural mechanisms. Finally, we revise available evidence for the existence of evolutionary adjustments of thermal characteristics in lacertid lizards. Existing studies have mainly dealt with within- and among-species differences in thermoregulatory behaviour (selected temperatures) and thermal physiology of adults (optimal temperatures, heating rates). Available data provide only limited evidence for clear-cut evolutionary shifts in thermal physiology characteristics along climatic gradients.Raspravlja se o tri aspekta termalne biologije lacertidnih guštera. Prvo donosimo pregled dostupnih podataka o tjelesnoj temperaturi u prirodi (Tb), termalnoj osjetljivosti različitih funkcija i odabranih temperatura tijela kod različitih vrsta lacertidnih guštera. Također se ukratko daju informacije o mehanizmima termoregulacije. Drugo, raspravlja se o nedavnim pokušajima procjene »preciznosti« termoregulacije i koji je doprinos određenih mehanizama ponašanja. Na kraju se daje pregled dostupnih dokaza o postojanju evolucijskih prilagodbi termalnih osobina lacertidnih gušterica. Postojeće studije su se uglavnom bavile razlikama u termoregulacijskom ponašanju (odabrane temperature) unutar jedne i između više vrsta i termalnom fiziologijom adulta (optimalne temperature, zagrijavanje). Dostupni podaci daju samo ograničene dokaze o jasno određenim evolucijskim pomacima u karakteristikama termalne fiziologije duž klimatskih gradijenata

The evolution of thermal performance curves in semi-aquatic newts: Thermal specialists on land and thermal generalists in water?

a b s t r a c t The position and shape of thermal performance curves (TPCs, the functions relating temperature to physiological performance) for ecologically relevant functions will directly affect the fitness of ectotherms and therefore should be under strong selection. However, thermodynamic considerations predict that relationships between the different components of the TPC will confound its evolutionary optimization. For instance, the ''jack-of-all-temperatures'' hypothesis predicts a trade-off between the breadth of the TPC and the maximal performance capacity; the ''warmer is better'' hypothesis suggests that low thermal optima will come with low absolute performances. Semi-aquatic organisms face the additional challenge of having to adjust their TPCs to two environments that are likely to differ in mean temperature and thermal variability. In this paper, we examine how parameters of the TPCs for maximal running and swimming speed have co-evolved in the semi-aquatic newt genus Triturus. We consider evolutionary relationships between the width and the height of the TPCs, the optimal temperatures and maximal performance. Phylogenetic comparative analyses reveal that in Triturus, swimming and running differ substantially in the (co-)variation of TPC parameters. Whereas evolutionary changes in the TPC for swimming primarily concern the shape of the curve (generalist versus specialist), most interspecific variation in running speed TPCs involves shifts in overall performance across temperatures

Rasprostranjenost vodozemaca i gmazova u Parku prirode »Lastovsko otočje«: mogući biotički i abiotički uzroci

In this paper we examine the distribution of amphibians and reptiles over the islands of the newly founded Lastovo Archipelago Nature Park (Lastovsko otočje), Croatia. On several field trips between 1996 and 2008, we encountered five species of lizards (Podarcis sicula, P. melisellensis, Dalmatolacerta oxycephala, Hemidactylus turcicus and Pseudopus apodus), one species of snake (Dolichophis caspius), one species of sea turtle (Caretta caretta) and one species of toad (Bufo viridis). We confirm literature data on the presence of some of these species on different islands of the archipelago, and add distributional records for several other islands and islets. Logistic regression analyses show that the variables predicting presence/absence from different islands vary among species. Within species, populations from different islands noticeably vary in body size and shape, scalation, dorsal and ventral coloration, behaviour and density. This observation adds to the value of the study area as a »natural laboratory« for future research into the ecology and evolution of island populations. Although most species seem to be doing well presently, we list a number of possible hazards and concerns.U ovom radu istražujemo distribuciju vodozemaca i gmazova novoosnovanog Parka prirode »Lastovsko otočje«, Hrvatska. Tijekom višestrukih terenskih posjeta u periodu od 1996. do 2008. godine zabilježili smo pet vrsta guštera (Podarcis sicula, P. melisellensis, Dalmatolacerta oxycephala, Hemidactylus turcicus i Pseudopus apodus), jednu vrstu zmije (Dolichophis caspius), jednu vrstu morske kornjače (Caretta caretta) i jednu vrstu žabe (Bufo viridis). Potvrdili smo prisutnost određenih vrsta na pojedinim otocima Lastovskog otočja, te dodali nalaze na mnogim drugim otocima i otočićima. Logističkom regresijskom analizom smo pokazali da varijable koje predviđaju prisutnost / odsutnost s različitih otoka variraju između vrsta. Unutar vrste, populacije s različitih otoka zapaženo variraju u veličini i obliku tijela, broju i izgledu pločica, leđnoj i trbušnoj obojenosti, ponašanju i gustoći. Ova opažanja povećavaju vrijednost istraživanog područja kao »prirodnog laboratorija« za buduća istraživanja ekologije i evolucije otočkih populacija. Iako se čini je većina vrsta u dobrom stanju, navodimo listu mogućih opasnih i zabrinjavajućih čimbenika

The growing caseload of chronic life-long conditions calls for a move towards full self-management in low-income countries

<p>Abstract</p> <p>Background</p> <p>The growing caseload caused by patients with chronic life-long conditions leads to increased needs for health care providers and rising costs of health services, resulting in a heavy burden on health systems, populations and individuals. The professionalised health care for chronic patients common in high income countries is very labour-intensive and expensive. Moreover, the outcomes are often poor. In low-income countries, the scarce resources and the lack of quality and continuity of health care result in high health care expenditure and very poor health outcomes. The current proposals to improve care for chronic patients in low-income countries are still very much provider-centred.</p> <p>The aim of this paper is to show that present provider-centred models of chronic care are not adequate and to propose 'full self-management' as an alternative for low-income countries, facilitated by expert patient networks and smart phone technology.</p> <p>Discussion</p> <p>People with chronic life-long conditions need to 'rebalance' their life in order to combine the needs related to their chronic condition with other elements of their life. They have a crucial role in the management of their condition and the opportunity to gain knowledge and expertise in their condition and its management. Therefore, people with chronic life-long conditions should be empowered so that they become the centre of management of their condition. In full self-management, patients become the hub of management of their own care and take full responsibility for their condition, supported by peers, professionals and information and communication tools.</p> <p>We will elaborate on two current trends that can enhance the capacity for self-management and coping: the emergence of peer support and expert-patient networks and the development and distribution of smart phone technology both drastically expand the possibilities for full self-management.</p> <p>Conclusion</p> <p>Present provider-centred models of care for people with chronic life-long conditions are not adequate and we propose 'full self-management' as an alternative for low-income countries, supported by expert networks and smart phone technology.</p

Trade-offs between speed and endurance in the frog Xenopus laevis: a multi-level approach

One of the most interesting trade-offs within the vertebrate locomotor system is that between speed and endurance capacity. However, few studies have demonstrated a conflict between whole-animal speed and endurance within a vertebrate species. We investigated the existence of trade-offs between speed and endurance capacity at both the whole-muscle and whole-animal levels in post-metamorphs of the frog Xenopus laevis. The burst-swimming performance of 55 frogs was assessed using a high-speed digital camera, and their endurance capacity was measured in a constant-velocity swimming flume. The work-loop technique was used to assess maximum power production of whole peroneus muscles at a cycle frequency of 6 Hz, while fatigue-resistance was determined by recording the decrease in force and net power production during a set of continuous cycles at 2 Hz. We found no significant correlations between measures of burst swimming performance and endurance capacity, suggesting that there is no trade-off between these two measures of whole-animal performance. In contrast, there was a significant negative correlation between peak instantaneous power output of the muscles at 6 Hz and the fatigue-resistance of force production at 2 Hz (other correlations between power and fatigue were negative but non-significant). Thus, our data support the suggestion that a physiological conflict between maximum power output and fatigue resistance exists at the level of vertebrate muscles. The apparent incongruence between whole-muscle and whole-animal performance warrants further detailed investigation and may be related to factors influencing both whole-muscle and whole-animal performance measures

Proximate causes of intraspecific variation in locomotor performance in the lizard Gallotia galloti

ABSTRACT To understand the evolution of biological traits, information on the degree and origins of intraspecific variation is essential. Because adaptation can take place only if the trait shows heritable variation, it is important to know whether (at least) part of the trait variation is genetically based. We describe intraand interindividual variation in three performance measures (sprint speed, climbing, and clambering speed) in juvenile Gallotia galloti lizards from three populations and examine how genetic, environmental (incubation temperature), and ontogenetic (age, size) effects interact to cause performance variation. Moreover, we test whether the three performance traits are intercorrelated phenotypically and genetically. Sprint speed is highest in juveniles incubated at the lowest temperature (26ЊC) irrespective of population. Climbing speed differs among populations, and the differences persist at least until the lizards are 30 wk old. This suggests that the three populations experience different selective pressures. Moreover, mass, snoutvent length, and hindlimb length seem to affect climbing performance differently in the three populations. The variation in sprinting and climbing ability appears to be genetically based. Moreover, the two performance traits are intercorrelated and thus will not evolve independently from each other. Clambering speed (i.e., capacity to climb up an inclined mesh) varies among individuals, but the origin of this variation remains obscure

Anatomical and physiological changes associated with a recent dietary shift in the lizard Podarcis sicula

ABSTRACT Dietary shifts have played a major role in the evolution of many vertebrates. The idea that the evolution of herbivory is physiologically constrained in squamates is challenged by a number of observations that suggest that at least some lizards can overcome the putative physiological difficulties of herbivory on evolutionary and even ecological timescales. We compared a number of morphological and physiological traits purportedly associated with plant consumption between two island populations of the lacertid lizard Podarcis sicula. Previous studies revealed considerable differences in the amount of plant material consumed between those populations. We continued the investigation of this study system and explored the degree of divergence in morphology (dentition, gut morphology), digestive performance (gut passage time, digestive efficiency), and ecology (endosymbiont density). In addition, we also performed a preliminary analysis of the plasticity of some of these modifications. Our results confirm and expand earlier findings concerning divergence in the morphology of feeding structures between two island populations of P. sicula lizards. In addition to the differences in skull dimensions and the prevalence of cecal valves previously reported, these two recently diverged populations also differ in aspects of their dentition (teeth width) and the lengths of the stomach and small intestine. The plasticity experiment suggests that at least some of the changes associated with a dietary shift toward a higher proportion of plant material may be plastic. Our results also show that these morphological changes effectively translate into differences in digestive performance: the population with the longer digestive tract exhibits longer gut passage time and improved digestive efficiency

Rasprostranjenost vodozemaca i gmazova u Parku prirode »Lastovsko otočje«: mogući biotički i abiotički uzroci

In this paper we examine the distribution of amphibians and reptiles over the islands of the newly founded Lastovo Archipelago Nature Park (Lastovsko otočje), Croatia. On several field trips between 1996 and 2008, we encountered five species of lizards (Podarcis sicula, P. melisellensis, Dalmatolacerta oxycephala, Hemidactylus turcicus and Pseudopus apodus), one species of snake (Dolichophis caspius), one species of sea turtle (Caretta caretta) and one species of toad (Bufo viridis). We confirm literature data on the presence of some of these species on different islands of the archipelago, and add distributional records for several other islands and islets. Logistic regression analyses show that the variables predicting presence/absence from different islands vary among species. Within species, populations from different islands noticeably vary in body size and shape, scalation, dorsal and ventral coloration, behaviour and density. This observation adds to the value of the study area as a »natural laboratory« for future research into the ecology and evolution of island populations. Although most species seem to be doing well presently, we list a number of possible hazards and concerns.U ovom radu istražujemo distribuciju vodozemaca i gmazova novoosnovanog Parka prirode »Lastovsko otočje«, Hrvatska. Tijekom višestrukih terenskih posjeta u periodu od 1996. do 2008. godine zabilježili smo pet vrsta guštera (Podarcis sicula, P. melisellensis, Dalmatolacerta oxycephala, Hemidactylus turcicus i Pseudopus apodus), jednu vrstu zmije (Dolichophis caspius), jednu vrstu morske kornjače (Caretta caretta) i jednu vrstu žabe (Bufo viridis). Potvrdili smo prisutnost određenih vrsta na pojedinim otocima Lastovskog otočja, te dodali nalaze na mnogim drugim otocima i otočićima. Logističkom regresijskom analizom smo pokazali da varijable koje predviđaju prisutnost / odsutnost s različitih otoka variraju između vrsta. Unutar vrste, populacije s različitih otoka zapaženo variraju u veličini i obliku tijela, broju i izgledu pločica, leđnoj i trbušnoj obojenosti, ponašanju i gustoći. Ova opažanja povećavaju vrijednost istraživanog područja kao »prirodnog laboratorija« za buduća istraživanja ekologije i evolucije otočkih populacija. Iako se čini je većina vrsta u dobrom stanju, navodimo listu mogućih opasnih i zabrinjavajućih čimbenika

Characterization of the natural variation in Arabidopsis thaliana metabolome by the analysis of metabolic distance

Metabolite fingerprinting is widely used to unravel the chemical characteristics of biological samples. Multivariate data analysis and other statistical tools are subsequently used to analyze and visualize the plasticity of the metabolome and/or the relationship between those samples. However, there are limitations to these approaches for example because of the multi-dimensionality of the data that makes interpretation of the data obtained from untargeted analysis almost impossible for an average human being. These limitations make the biological information that is of prime importance in untargeted studies be partially exploited. Even in the case of full exploitation, current methods for relationship elucidation focus mainly on between groups variation and differences. Therefore, a measure that is capable of exploiting both between- and within-group biological variation would be of great value. Here, we examined the natural variation in the metabolome of nine Arabidopsis thaliana accessions grown under various environmental conditions and established a measure for the metabolic distance between accessions and across environments. This data analysis approach shows that there is just a minor correlation between genetic and metabolic diversity of the nine accessions. On the other hand, it delivers so far in Arabidopsis unexplored chemical information and is shown to be biologically relevant for resistance studies