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1.
J Insect Physiol ; 106(Pt 3): 163-171, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29278714

RESUMO

In the face of global warming, both the absolute thermal tolerance of an ectotherm, and its ability to shift its tolerance level via acclimation, are thought to be fundamentally important. Understanding the links between tolerance and its plasticity is therefore critical to accurately predict vulnerability to warming. Previous studies in a number of ectotherm taxa suggest trade-offs in the evolution of thermal tolerance and its plasticity, something which does not, however, apply to Deronectes diving beetles, where these traits are instead positively correlated. Here we revisit the relationship between thermal tolerance and plasticity in these beetles, paying attention to a recently discovered morphological adaptation supporting under water respiration - setal tracheal gills. Hollow setae on the elytra interconnect with the beetle's tracheal system, providing a gas exchange surface that allows oxygen to be extracted directly from the water. This enables individuals to stay submerged for longer than their subelytral air stores would allow. We show that hypoxia reduced heat tolerance, especially when individuals were denied access to air, forcing them to rely solely on aquatic gas exchange. Species with higher densities of these gas-exchanging setae exhibited improved cold tolerance, but reduced heat tolerance and lower plasticity of heat tolerance. Differences in setal tracheal gill density across species were also related to habitat use: species with low gill density were found mainly in intermittent, warmer rivers, where underwater gas exchange is more problematic and risks of surfacing may be smaller. Moreover, when controlling for differences in gill density we no longer found a significant relationship between heat tolerance and its plasticity, suggesting that the previously reported positive relationship between these variables may be driven by differences in gill density. Differences in environmental conditions between the preferred habitats could simultaneously select for characteristic differences in both thermal tolerance and gill density. Such simultaneous selection may have resulted in a non-causal association between cold tolerance and gill density. For heat tolerance, the correlations with gill density could reflect a causal relationship. Species relying strongly on diffusive oxygen uptake via setal tracheal gills may have a reduced oxygen supply capacity and may be left with fewer options for matching oxygen uptake to oxygen demand during acclimation, which could explain their reduced heat tolerance and limited plasticity. Our study helps shed light on the mechanisms that underpin thermal tolerance and plasticity in diving air-breathing ectotherms, and explores how differences in thermal tolerance across species are linked to their selected habitat, morphological adaptations and evolutionary history.


Assuntos
Besouros/fisiologia , Oxigênio/fisiologia , Termotolerância , Animais , Besouros/anatomia & histologia , Ecossistema , Brânquias/anatomia & histologia
2.
Biol Lett ; 12(9)2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27624796

RESUMO

There is a current surge of research interest in the potential role of developmental plasticity in adaptation and evolution. Here we make a case that some of this research effort should explore the adaptive significance of heterokairy, a specific type of plasticity that describes environmentally driven, altered timing of development within a species. This emphasis seems warranted given the pervasive occurrence of heterochrony, altered developmental timing between species, in evolution. We briefly review studies investigating heterochrony within an adaptive context across animal taxa, including examples that explore links between heterokairy and heterochrony. We then outline how sequence heterokairy could be included within the research agenda for developmental plasticity. We suggest that the study of heterokairy may be particularly pertinent in (i) determining the importance of non-adaptive plasticity, and (ii) embedding concepts from comparative embryology such as developmental modularity and disassociation within a developmental plasticity framework.


Assuntos
Adaptação Fisiológica , Desenvolvimento Embrionário/fisiologia , Meio Ambiente , Animais , Embrião de Mamíferos/fisiologia , Embrião não Mamífero/fisiologia , Epigênese Genética , Fenótipo
3.
Mar Environ Res ; 112(Pt A): 44-51, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26392350

RESUMO

Ocean acidification (OA) is occurring at a fast rate, resulting in changes of carbonate chemistry in the oceans and in lowering of the pH. Previous studies have documented significant changes in the antioxidant defenses of marine species in response to OA. Here, selected polychaete species, Platynereis dumerilii, Polyophthalmus pictus and Syllis prolifera, were sampled from a natural CO2 vent system (pH = 7.3) and from a non-venting 'control' site (pH = 8.1), and reciprocally transplanted in these areas for 30 days. Total antioxidant capacity toward different forms of oxyradicals was compared in native and transplanted polychaetes: the aim was to assess whether the environmental conditions at the vent site would act as a prooxidant stressor, and the capability of polychaetes to modulate their antioxidant capacity to counteract a varied oxyradicals formation. None of the investigated species enhanced the antioxidant potential during the experiment. A significant reduction of the capability to neutralize different forms of oxyradicals was observed in P. pictus and, partially, in S. prolifera when transplanted from control to naturally-acidified conditions. On the other hand, populations of P. dumerilii originating from the vent and of S. prolifera from both control and acidified sites, showed higher constitutive antioxidant efficiency toward peroxyl radicals and peroxynitrite, which may allow them to cope with short-term and chronic exposure to higher oxidative pressure without further enhancement of antioxidant defenses. Since low pH - high pCO2 is the greatest environmental difference between the control and the vent sites, we suggest that the pro-oxidant challenge due to such peculiarities may have different biological consequences in different polychaete species. Some appear more susceptible to oxidative effects, while others acquire a long term acclimatization to vent conditions through the enhancement of their basal antioxidant protection.


Assuntos
Antioxidantes/metabolismo , Carbonatos/análise , Estresse Oxidativo , Poliquetos/fisiologia , Água do Mar/química , Aclimatação , Animais , Dióxido de Carbono/análise , Concentração de Íons de Hidrogênio , Itália , Especificidade da Espécie
4.
J Exp Biol ; 217(Pt 14): 2499-508, 2014 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-24803457

RESUMO

The distribution patterns of many species in the intertidal zone are partly determined by their ability to survive and recover from tidal emersion. During emersion, most crustaceans experience gill collapse, impairing gas exchange. Such collapse generates a state of hypoxemia and a hypercapnia-induced respiratory acidosis, leading to hyperlactaemia and metabolic acidosis. However, how such physiological responses to emersion are modified by prior exposure to elevated CO2 and temperature combinations, indicative of future climate change scenarios, is not known. We therefore investigated key physiological responses of velvet swimming crabs, Necora puber, kept for 14 days at one of four pCO2/temperature treatments (400 µatm/10°C, 1000 µatm/10°C, 400 µatm/15°C or 1000 µatm/15°C) to experimental emersion and recovery. Pre-exposure to elevated pCO2 and temperature increased pre-emersion bicarbonate ion concentrations [HCO3(-)], increasing resistance to short periods of emersion (90 min). However, there was still a significant acidosis following 180 min emersion in all treatments. The recovery of extracellular acid-base via the removal of extracellular pCO2 and lactate after emersion was significantly retarded by exposure to both elevated temperature and pCO2. If elevated environmental pCO2 and temperature lead to slower recovery after emersion, then some predominantly subtidal species that also inhabit the low to mid shore, such as N. puber, may have a reduced physiological capacity to retain their presence in the low intertidal zone, ultimately affecting their bathymetric range of distribution, as well as the structure and diversity of intertidal assemblages.


Assuntos
Braquiúros/metabolismo , Dióxido de Carbono/metabolismo , Temperatura Alta/efeitos adversos , Água do Mar/química , Acidose , Animais , Mudança Climática , Concentração de Íons de Hidrogênio , Hipercapnia , Ondas de Maré
5.
Integr Comp Biol ; 53(4): 660-70, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23660590

RESUMO

The injection of anthropogenically-produced CO2 into the atmosphere will lead to an increase in temperature and a decrease in pH at the surface of the oceans by 2100. Marine intertidal organisms possess the ability to cope in the short term with environmental fluctuations exceeding predicted values. However, how they will cope with chronic exposure to elevated temperature and pCO2 is virtually unknown. In addition, individuals from the same species/population often show remarkable levels of variation in their responses to complex climatic changes: in particular, variation in metabolic rates often is linked to differences in individuals' performances and fitness. Despite its ecological and evolutionary importance, inter-individual variation has rarely been investigated within the context of climatic changes, and most investigations have typically employed orthogonal experimental designs paired to analyses of independent samples. Although this is undoubtedly a powerful and useful approach, it may not be the most appropriate for understanding all alterations of biological functions in response to environmental changes. An individual approach arguably should be favored when trying to describe organisms' responses to climatic change. Consequently, to test which approach had the greater power to discriminate the intensity and direction of an organism's response to complex climatic changes, we investigated the extracellular osmo/iono-regulatory abilities, upper thermal tolerances (UTTs), and metabolic rates of individual adults of an intertidal amphipod, Echinogammarus marinus, exposed for 15 days to combined elevated temperature and pCO2. The individual approach led to stronger and different predictions on how ectotherms will likely respond to ongoing complex climatic change, compared with the independent approaches. Consequently, this may call into question the relevance, or even the validity, of some of the predictions made to date. Finally, we argue that treating individual differences as biologically meaningful can lead to a better understanding of the physiological responses themselves and the selective processes that will occur with complex climatic changes; selection will likely play a crucial role in defining species' responses to future environmental changes. Individuals with higher metabolic rates were also characterized by greater extracellular osmo/iono-regulative abilities and higher UTTs, and thus there appeared to be no evolutionary trade-offs between these functions. However, as individuals with greater metabolic rates also have greater costs for maintenance and repair, and likely a lower fraction of energy available for growth and reproduction, trade-offs between life-history and physiological performance may still arise.


Assuntos
Aclimatação/fisiologia , Anfípodes/fisiologia , Mudança Climática , Estuários , Osmorregulação/fisiologia , Estresse Fisiológico/fisiologia , Análise de Variância , Animais , Dióxido de Carbono/análise , Metabolismo Energético/fisiologia , Inglaterra , Concentração de Íons de Hidrogênio , Masculino , Oceanos e Mares , ATPase Trocadora de Sódio-Potássio/metabolismo , Temperatura Ambiente
6.
Mar Pollut Bull ; 73(2): 470-84, 2013 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-23428288

RESUMO

To reduce the negative effect of climate change on Biodiversity, the use of geological CO2 sequestration has been proposed; however leakage from underwater storages may represent a risk to marine life. As extracellular homeostasis is important in determining species' ability to cope with elevated CO2, we investigated the acid-base and ion regulatory responses, as well as the density, of sea urchins living around CO2 vents at Vulcano, Italy. We conducted in situ transplantation and field-based laboratory exposures to different pCO2/pH regimes. Our results confirm that sea urchins have some ability to regulate their extracellular fluid under elevated pCO2. Furthermore, we show that even in closely-related taxa divergent physiological capabilities underlie differences in taxa distribution around the CO2 vent. It is concluded that species distribution under the sort of elevated CO2 conditions occurring with leakages from geological storages and future ocean acidification scenarios, may partly be determined by quite subtle physiological differentiation.


Assuntos
Dióxido de Carbono/análise , Ecossistema , Ouriços-do-Mar/fisiologia , Poluentes Químicos da Água/análise , Adaptação Fisiológica , Animais , Mudança Climática , Fenômenos Geológicos , Concentração de Íons de Hidrogênio , Itália , Água do Mar/química
7.
J Evol Biol ; 25(2): 329-41, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22151892

RESUMO

Surfacing behaviour is fundamental in the ecology of aquatic air-breathing organisms; however, it is only in vertebrates that the evolutionary ecology of diving has been well characterized. Here, we explore the diving behaviour of dytiscid beetles, a key group of surface-exchanging freshwater invertebrates, by comparing the dive responses of 25 taxa (Deronectes and Ilybius spp.) acclimated at two temperatures. The allometric slopes of dive responses in these dytiscids appear similar to those of vertebrate ectotherms, supporting the notion that metabolic mode shapes the evolution of diving performance. In both genera, beetles spend more time submerged than on the surface, and surface time does not vary with the temperature of acclimation. However, presumably in order to meet increased oxygen demand at higher temperatures, Deronectes species increase surfacing frequency, whereas Ilybius species decrease dive time, an example of 'multiple solutions.' Finally, widespread northern species appear to possess higher diving performances than their geographically restricted southern relatives, something which may have contributed to their range expansion ability.


Assuntos
Besouros/fisiologia , Mergulho , Animais , Comportamento Animal , Evolução Biológica , Besouros/metabolismo , Filogenia , Temperatura Ambiente
8.
Fish Shellfish Immunol ; 30(6): 1209-22, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21463691

RESUMO

The inception of ecological immunology has led to an increase in the number of studies investigating the impact of environmental stressors on host immune defence mechanisms. This in turn has led to an increased understanding of the importance of invertebrate groups for immunological research. This review discusses the advances made within marine invertebrate ecological immunology over the past decade. By demonstrating the environmental stressors tested, the immune parameters typically investigated, and the species that have received the greatest level of investigation, this review provides a critical assessment of the field of marine invertebrate ecological immunology. In highlighting the methodologies employed within this field, our current inability to understand the true ecological significance of any immune dysfunction caused by environmental stressors is outlined. Additionally, a number of examples are provided in which studies successfully demonstrate a measure of immunocompetence through alterations in disease resistance and organism survival to a realized pathogenic threat. Consequently, this review highlights the potential to advance our current understanding of the ecological and evolutionary significance of environmental stressor related immune dysfunction. Furthermore, the potential for the advancement of our understanding of the immune system of marine invertebrates, through the incorporation of newly emerging and novel molecular techniques, is emphasized.


Assuntos
Ecossistema , Imunidade Celular/imunologia , Imunidade Humoral/imunologia , Imunidade Inata/imunologia , Invertebrados/imunologia , Estresse Fisiológico/imunologia , Animais , Peptídeos Catiônicos Antimicrobianos/imunologia , Biologia Marinha , Oceanos e Mares , Fagocitose/imunologia , Explosão Respiratória/imunologia , Especificidade da Espécie
9.
Biol Lett ; 7(2): 285-7, 2011 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-20880860

RESUMO

Heterochrony, differences in the timing of developmental events between descendent species and their ancestors, is a pervasive evolutionary pattern. However, the origins of such timing changes are still not resolved. Here we show, using sequence analysis, that exposure to predator cues altered the timing of onset of several developmental events in embryos of two closely related gastropod species: Radix balthica and Radix auricularia. These timing alterations were limited to certain events and were species-specific. Compared with controls, over half (62%) of exposed R. auricularia embryos had a later onset of body flexing and an earlier occurrence of the eyes and the heart; in R. balthica, 67 per cent of exposed embryos showed a later occurrence of mantle muscle flexing and an earlier attachment to, and crawling on, the egg capsule wall. The resultant developmental sequences in treated embryos converged, and were more similar to one another than were the sequences of the controls for both species. We conclude that biotic agents can elicit altered event timing in developing gastropod embryos. These changes were species-specific, but did not occur in all individuals. Such developmental plasticity in the timing of developmental events could be an important step in generating interspecific heterochrony.


Assuntos
Sinais (Psicologia) , Desenvolvimento Embrionário , Lymnaea/embriologia , Comportamento Predatório , Animais , Olho/embriologia , Peixes/fisiologia , Coração/embriologia , Lymnaea/crescimento & desenvolvimento , Especificidade da Espécie , Fatores de Tempo
10.
Biol Lett ; 6(4): 525-8, 2010 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-20071391

RESUMO

Alarm substances elicit behavioural responses in a wide range of animals but effects on early embryonic development are virtually unknown. Here we investigated whether skin injury-induced alarm substances caused physiological responses in embryos produced by two Danio species (Danio rerio and Danio albolineatus). Both species showed more rapid physiological development in the presence of alarm substance, although there were subtle differences between them: D. rerio had advanced muscle contraction and heart function, whereas D. albolineatus had advanced heart function only. Hence, alarm cues from injured or dying fish may be of benefit to their offspring, inducing physiological responses and potentially increasing their inclusive fitness.


Assuntos
Comunicação Animal , Desenvolvimento Embrionário/efeitos dos fármacos , Reação de Fuga/fisiologia , Aptidão Genética/fisiologia , Feromônios/farmacologia , Peixe-Zebra/embriologia , Peixe-Zebra/metabolismo , Análise de Variância , Animais , Testes de Função Cardíaca/efeitos dos fármacos , Contração Muscular/efeitos dos fármacos , Especificidade da Espécie , Gravação em Vídeo
11.
Mar Environ Res ; 58(2-5): 781-5, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15178113

RESUMO

The effect of temperature on the heart rate (fH) of Carcinus maenas exposed to a sublethal nominal concentration (0.5 mg l(-1)) of copper is reported. Adult, intermoult males (4 cm carapace width) were collected from Stavanger Fjord (Norway) in August (seawater TEMPERATURE=17 degrees C) and maintained in the laboratory (fed ad libitum) at 5, 15 and 25 degrees C for 7 days. Following this holding period, crabs were exposed to waterborne copper at the same temperature. After 3 days of exposure, individual fH was measured using the non-invasive Computer Aided Physiological MONitoring system (CAPMON) method. Copper-exposed individuals demonstrated significantly increased fH compared with controls at 5 and 25 degrees C (P<0.01). It is inferred that physiological function in C. maenas may be more vulnerable to copper contamination at seasonal temperature extremes (5 and 25 degrees C) than at the 'standard' test temperature (15 degrees C). Additionally, cardiac arrest observed at 5 degrees C is interpreted as a physiological response to limit copper uptake while the erratic fH in the 25 degrees C group reflected enhanced copper toxicity.


Assuntos
Braquiúros/efeitos dos fármacos , Cobre/toxicidade , Frequência Cardíaca/efeitos dos fármacos , Temperatura Ambiente , Animais , Braquiúros/fisiologia , Parada Cardíaca/induzido quimicamente , Frequência Cardíaca/fisiologia , Masculino , Noruega , Água do Mar
12.
Artigo em Inglês | MEDLINE | ID: mdl-11282329

RESUMO

Electrophoretic examination of dissociated haemocyanin subunits from a number of amphipod, decapod and isopod crustaceans supports the hypothesis that subunit composition is species-specific, despite marked within-species variation in many species. General patterns of heterogeneity on native PAGE gels were also evident between groupings within the Amphipoda. Gammarid amphipods could be split into two groups; one characterised by a high degree of heterogeneity and the other by a low degree of heterogeneity. The talitrid amphipods generally displayed a low degree of heterogeneity similar to, although still distinct from, the second gammarid category. Haemocyanin from the Hyalidae, a family allied to the talitrids was highly heterogeneous, similar to the first gammarid group and unlike the talitrids. Isopod haemocyanin banding patterns were more similar to one another than to any of the amphipod or decapod species examined. In general, the molecular weights of the amphipod Hcs tended to be greater than those of the isopods, with the decapods being lowest of all. It is suggested that Hc subunit heterogeneity may be a useful tool for investigating speciation and speciation events, and for reliably separating very closely-related species (e.g. Gammarus spp.), purely on the basis of their Hc subunit compositions.


Assuntos
Crustáceos/química , Hemocianinas/química , Animais , Eletroforese em Gel de Poliacrilamida/métodos , Hemocianinas/análise , Subunidades Proteicas , Especificidade da Espécie
13.
Trends Ecol Evol ; 13(2): 70-4, 1998 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-21238203

RESUMO

The christening of the decline in the geographic extent of species from high to low latitudes as Rapoport's rule was a bold step. Allowing for a variety of potentially significant complications to the interpretation of empirical studies, evidence that this is indeed a general pattern is, at the very least, equivocal. The present taxonomically and regionally biased set of studies lend support to the recent suggestion that the pattern is a local phenomenon being expressed primarily in the Palaearctic and Nearctic above latitudes of 40-50°N. Five hypotheses have been proposed to explain the generation of latitudinal declines in range size where they do occur, with the past heavy emphasis on a climatic variability mechanism being eroded. Evidence is accruing in support of more than one such mechanism. Whatever the generality of the `rule', it has undoubtedly served to stimulate a consideration of the role of spatial variation in range sizes in several areas of research in ecology and evolution.

14.
Trends Ecol Evol ; 12(10): 381-2, 1997 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21238117
15.
J Exp Zool ; 270(6): 508-16, 1994 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-7798869

RESUMO

In newly hatched brine shrimp (Artemia franciscana) cardiac organogenesis and function could only take place with the onset of segmentation. Consequently differences in age, body size and temperature (in the range 22-34 degrees C) affected the ontogeny of cardiac activity only indirectly, through their influence on developmental stage. Once present the frequency of cardiac activity (heart beat) increased with increasing body size and concomitant differentiation of cardiac tissue. At least initially, (dry body weight 11-16 micrograms) heart rate was independent of temperature and weight specific heart rate was independent of body size. When differentiation neared completion, and cardiac growth switched to elongation (dry body weight > 16 micrograms), there was a change in the pattern of cardiac function. There was now a decrease in heart beat with increasing body size and weight specific heart rate showed an inverse relationship with body weight. Heart rate also became temperature dependent, although it remained relatively insensitive. In conclusion it is suggested that the ontogeny of cardiac function in Artemia is constrained by an anamorphic (direct) pattern of development where segment formation occurs post hatch. Early cardiac functioning cannot be predicted on an allometric basis, as cardiovascular structure and function changes qualitatively during ontogeny.


Assuntos
Coração/embriologia , Animais , Artemia , Circulação Sanguínea , Constituição Corporal , Peso Corporal , Cobre/farmacologia , Coração/efeitos dos fármacos , Coração/fisiologia , Temperatura Ambiente
16.
Comp Biochem Physiol C ; 100(3): 339-42, 1991.
Artigo em Inglês | MEDLINE | ID: mdl-1687526

RESUMO

1. We have assessed, using current literature, the respiratory consequences of water-borne heavy metal exposure in crustaceans and molluscs. 2. We suggest that in lethal and sub-lethal concentrations the essential metals Cu and Zn act on the respiratory system primarily by disrupting gill function which results in the development of internal hypoxia, although reparation can be accomplished even at "high" sub-lethal concentrations. 3. The more toxic xenobiotes such as Hg (and perhaps to a lesser extent Cd) may interfere with the respiratory system at every level of organisation including cellular respiration itself.


Assuntos
Crustáceos/efeitos dos fármacos , Metais/toxicidade , Moluscos/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Transporte Biológico/efeitos dos fármacos , Oxigênio/farmacocinética , Consumo de Oxigênio/efeitos dos fármacos , Respiração/efeitos dos fármacos
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