Understanding the impact of warming on organisms, communities and ecosystems is a central problem in ecology. Although species responses to warming are well documented, our ability to scale up to predict community and ecosystem properties is limited. Improving understanding of the mechanisms that link patterns and processes over multiple levels of organisation and across spatial and temporal scales promises to enhance our ability to predict whether the biosphere will exacerbate, or mitigate, climate warming. In this thesis, I combine ideas from metabolic theory with a variety of experimental approaches to further our understanding of how warming will impact photosynthesis and respiration across scales. Firstly, I show how phytoplankton can rapidly evolve increased thermal tolerance by downregulating rates of respiration more than photosynthesis. This increased carbon-use efficiency meant that evolved populations allocated more fixed carbon to growth. I then explore how constraints on individual physiology and community size structure influence phytoplankton community metabolism. Using metabolic theory, I link community primary production and respiration to the size- and temperature- dependence of individual physiology and the distribution of abundance and body size. Finally, I show that selection on photosynthetic traits within and across taxa dampens the effects of temperature on ecosystem-level gross primary production in a set of geothermal streams. Across the thermal-gradient, autotrophs from cold streams had higher photosynthetic rates than autotrophs from warm streams. At the ecosystem-level, the temperature-dependence of gross primary productivity was similar to that of organism-level photosynthesis. However, this was due to covariance between biomass and stream temperature; after accounting for the effects of biomass, gross primary productivity was independent of temperature. Collectively, this work emphasises the importance of ecological, evolutionary and physiological mechanisms that shape how metabolism responds to warming over multiple levels of organisation. Incorporating both the direct and indirect effects of warming on metabolism into predictions of the biosphere to climate futures should be considered a priority.

Earth mean surface temperature has increased by 1 °C since the industrial revolution, and this has already had considerable effects on animal and plant species. Ecological responses to the warming climate – often facilitated via phenotypic plasticity – are ubiquitous. However, even though evolution can occur rapidly there are only few examples of genetic adaptation to climate change. In my thesis, I used a near-natural system to study if and how organisms have adapted to 30 years of warming, and how this has affected competitive species interactions. I investigated Baltic Sea populations of the aquatic snails Galba truncatula and Theodoxus fluviatilis, which had been subjected to cooling water discharge from power plants, resulting in water temperatures 4 to 10 °C higher than in the surrounding sea. G. truncatula had high upper thermal limits and large acclimation potential. This plasticity may have helped the species to survive under the new conditions, allowing evolution through natural selection to take place. I found that the populations of the two thermal origins had diverged in SNP markers associated with warmer temperature, whereas divergence in selectively neutral markers was mainly related to geographical distance. Adaptation occurred from standing genetic variation, emphasizing the importance of genetic diversity and population size in enabling the persistence of populations. Changes in thermal sensitivity of growth and survival were subtle yet significant, and complied with theoretical models of thermal adaptation in ectotherms. At the community level, pre-adaptation to warmer conditions aided the native T. fluviatilis when competing with the alien Potamopyrgus antipodarum. However, interspecific competition limited the snails most in those traits favored under warming, highlighting the challenge of adapting to different selecting forces during global change. The persistence of species and populations under climate change depends on several factors - plasticity allowing for initial survival, evolvability in allowing the genetic changes, and species interactions affecting the new ecological niches. The results of my thesis indicate that persistence under climate change is possible when these factors align, but the relative roles of ecology and plasticity may explain why there are so few observed instances of evolution in response to climate change.

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: As ectotherms, lizards are particularly vulnerable to changes in the thermal landscape and face extinction risk if they lack the capacity to rapidly adapt or behaviourally mitigate increasingly altered thermal environments. Theoretical models that predict lizards‟ response to climate change often fail to take into account the thermal characteristics of the microenvironment, the ability of lizards to behaviourally buffer climate variation in the habitat and the plastic nature of both behaviour and physiology over ecologically relevant time-scales. Here, I address this major knowledge gap using two separate research chapters in an experimental physiology approach. In Chapter 1, I investigated the temperature-dependence and plasticity of resting metabolic rate, water-loss rate and preferred body temperature of Cordylus oelofseni at several temporal scales (within and between seasons) and incorporated field observations to acquire a better understanding of this species‟ adaptive potential to buffer thermal changes in the habitat. Cordylus oelofseni showed plasticity of both behaviour and physiology in response to thermal acclimation, but relied on distinct strategies depending on the time-scale investigated. These results highlighted the complexity of underlying mechanisms used by these organisms to buffer temperature variation. In Chapter 2, I used an experimental approach to examine the energetic costs of thermoregulation in C. oelofseni and test the cost-benefit model of thermoregulation. This model‟s primary prediction states that lizards should thermoregulate carefully only when the associated costs are low. Using four enclosures that simulated different thermal qualities (temporal and spatial distributions of operative temperatures) in the habitat, I found limited support for the cost-benefit model. Lizards in the low-quality heterogeneous enclosures invested the same energetic effort and thermoregulated with similar overall accuracy as lizards in the high-quality heterogeneous enclosure. The costs incurred were not necessarily energetic, but reflected missed opportunities (e.g. less time to forage), something that, along with important interaction effects with body mass, deserves further attention when testing this model. Together, these results illustrate the importance of incorporating ecological reality at various time and spatial scales in order to make relevant predictions regarding the fate of lizards with projected climate change. / AFRIKAANSE OPSOMMING: As ektotermiese diere, is akkedisse veral sensitief vir veranderinge in die termiese landskap en staar uitsterwingsrisiko in die gesig as hulle nie die vermoë het om vinnig aan te pas of gedragsveranderinge te maak in omgewings wat toenemend verwarm nie. Teoretiese modelle wat akkedisse se reaksie op klimaatsverandering voorspel, neem dikwels nie die termiese eienskappe van die mikro-omgewing, die vermoë van akkedisse om met gedragsveranderinge klimaat variasie in die habitat te buffer en die plastieke aard van beide gedrag en fisiologie oor ekologies relevante tydskale in ag nie. Hier bespreek ek hierdie groot kennisgaping met behulp van twee afsonderlike navorsingshoofstukke in 'n eksperimentele fisiologie benadering. In Hoofstuk 1 het ek ondersoek ingestel na die temperatuur-afhanklikheid en plastisiteit van rustende metaboliese tempo, waterverlies tempo en voorkeur liggaamstemperatuur van Cordylus oelofseni by verskeie tydskale (binne en tussen seisoene) en inkorporeer veld waarnemings om 'n beter begrip te verkry van hierdie spesie se aanpasbare potensiaal om termiese veranderinge in die habitat te buffer. Cordylus oelofseni het plastisiteit van beide gedrag en fisiologie in reaksie op hitte-akklimatisering getoon, maar staatgemaak op verskillende strategieë, afhangende van die tyd-skaal wat ondersoek is. Hierdie resultate beklemtoon die kompleksiteit van die onderliggende meganismes wat gebruik word deur hierdie organisme om temperatuur verandering te buffer. In Hoofstuk 2 het ek 'n eksperimentele benadering gebruik om die energiekoste van termoregulering in C. oelofseni te ondersoek en die kostevoordeel model van termoregulering te toets. Hierdie model se primêre voorspelling verklaar dat akkedisse slegs versigtig moet termoreguleer wanneer die gepaardgaande koste laag is. Deur gebruik te maak van vier afskortings wat verskillende termiese eienskappe gesimuleer het (tyd en ruimtelike verspreiding van operatiewe temperature) in die habitat, het ek beperkte ondersteuning gevind vir die koste-voordeel model. Akkedisse in die lae-gehalte heterogene afskortings het dieselfde energieke moeite belê en getermoreguleer met soortgelyke algehele akkuraatheid as akkedisse in die hoë-gehalte heterogene kamp. Die kostes wat aangegaan is, is nie noodwendig energiek nie, maar weerspieël geleenthede wat gemis is (bv. minder tyd om kos te soek), iets wat, saam met belangrike interaksie effekte met liggaamsmassa, verdere aandag verdien wanneer hierdie model getoets word. Tesame illustreer hierdie resultate die belangrikheid van die integrasie van ekologiese werklikheid op verskillende tyd en ruimtelike skale, om relevante voorspellings oor die lot van akkedisse met geprojekteerde klimaatsverandering te kan maak.

<p>This research examines three potential mechanisms by which bacteria can adapt to different temperatures: changes in strain-level population structure, gene regulation and particle colonization. For the first two mechanisms, I utilize bacterial strains from the Vibrionaceae family due to their ease of culturability, ubiquity in coastal environments and status as a model system for marine bacteria. I first examine vibrio seasonal dynamics in temperate, coastal water and compare the thermal performance of strains that occupy different thermal environments. Our results suggest that there are tradeoffs in adaptation to specific temperatures and that thermal specialization can occur at a very fine phylogenetic scale. The observed thermal specialization over relatively short evolutionary time-scales indicates that few genes or cellular processes may limit expansion to a different thermal niche. I then compare the genomic and transcriptional changes associated with thermal adaptation in closely-related vibrio strains under heat and cold stress. The two vibrio strains have very similar genomes and overall exhibit similar transcriptional profiles in response to temperature stress but their temperature preferences are determined by differential transcriptional responses in shared genes as well as temperature-dependent regulation of unique genes. Finally, I investigate the temporal dynamics of particle-attached and free-living bacterial community in coastal seawater and find that microhabitats exert a stronger forcing on microbial communities than environmental variability, suggesting that particle-attachment could buffer the impacts of environmental changes and particle-associated communities likely respond to the presence of distinct eukaryotes rather than commonly-measured environmental parameters. Integrating these results will offer new perspectives on the mechanisms by which bacteria respond to seasonal temperature changes as well as potential adaptations to climate change-driven warming of the surface oceans.</p> / Dissertation

O grande sucesso ecológico dos insetos sociais se deve, em grande parte, ao controle das condições climáticas do ninho, entre as quais é possível destacar a temperatura como uma das variáveis mais importantes. Nas abelhas sem ferrão, um grupo de abelhas eussociais com cerca de 400 espécies distribuidas pela região Neotropical, apesar dos poucos estudos existentes é possível identificar uma grande variedade de estratégias para lidar com a heterogeneidade térmica do ambiente. Em comparação com Apis mellifera (o inseto social mais bem estudado no mundo), é possível verificar, de maneira geral, uma menor capacidade termorregulatória nas abelhas sem ferrão. Portanto, isto coloca as abelhas sem ferrão como importantes modelos que podem permitir a melhor compreensão da evolução da diversidade de estratégias de sucesso nos insetos sociais para lidar com a heterogeneidade térmica. Adicionalmente, as abelhas sem ferrão realizam a polinização, um serviço ambiental chave para a manutenção dos ecossistemas Neotropicais. Dessa forma é necessário conhecer as adaptações térmicas nestes organismos, principalmente as voltadas para as altas temperaturas, para que possam ajudar a prever os impactos das mudanças climáticas nestes organismos. Assim, o objetivo deste estudo foi investigar a capacidade e os mecanismos termorregulatórios em abelhas sem ferrão, bem como alguns aspectos da sensibilidade térmica sob condições de altas temperaturas, usando para isso a espécie Scaptotrigona depilis como organismo modelo. Verificamos que essas abelhas são capazes de resfriar o ninho e para isto, utilizam pelo menos dois mecanismos: a ventilação e a coleta de água para resfriamento evaporativo. Este último comportamento foi observado pela primeira vez em um contexto colonial e natural. Adicionalmente foi verificado que a umidade relativa do ar dentro dos ninhos varia consideravelmente menos que a umidade relativa do ar ambiente, muito provalvemente por conta das fontes de umidade (néctar e água) e do isolamento da cavidade de nidificação. Verificamos que a taxa de construção de células de cria sofre uma diminuição sutil com o aumento da temperatura ambiente e quase nenhuma influência da temperatura do ninho. Finalmente, verificamos que o tempo de desenvolvimento do estágio pupal até o adulto diminui conforme a temperatura de incubação aumenta. Da mesma forma acontece com a mortalidade, porém esta aumenta drasticamente após atingir uma temperatura limite. Demonstramos que existem adaptações claras para o resfriamento do ninho em S. depilis, contradizendo as hipóteses atuais de que a nidificação em cavidades termicamente isoladas seria a principal forma de manter a temperatura em níveis relativamente constantes, supostamente necessários para o crescimento e manutenção da colônia. Adicionalmente, sugerimos que a temperatura dos ninhos varia consideravelmente (mesmo com o isolamento das cavidades e com os mecanismos ativos de termorregulação), porém o desempenho das atividades das abelhas no ninho é regular dentro de uma ampla faixa de temperaturas, i.e., as abelhas sem ferrão devem suportar uma ampla variação de temperaturas. / The great ecological success of the social insects is due, in large part, to their capacity of nest climate control, which it is possible to highlight the temperature as one of the most important variable. The stingless bees, a megadiverse group of eusocial bees with about 400 species on the Neotropical zone, show a great variety of strategies to deal with the thermal heterogeneity of the environment. Compared to Apis mellifera, (the social insect better studied in the world), it is possible to verify in general, that stingless bees have a low thermoregulatory capacity. Because of that different capacity and other biological features, stingless bees are excellent models to test hypothesis that focus on the evolution of diversity of strategies to deal with thermal heterogeneity in social insects and the consequent success in this group. Additionally, stingless bees are responsible for the pollination of an extensive number of vegetal species, which is a key environmental service to the maintenance of the tropical ecosystems. So, knowing their thermal adaptations, mainly the related to high temperatures, is indispensable in this moment, yet this knowledge will help to prevent the impact of global climate changes on this organisms. Thus, the aim of this study was to investigate the mechanisms and the thermoregulatory capacity in stingless bees, as well as some aspects of thermal sensibility under high temperature conditions, using the specie Scapotrigona depilis as model organism. We verified that the specie is capable of cool their nests and, for that, use at least two mechanisms: ventilation and water collection for evaporative cooling. This last behavior was observed for the first time in a colonial and natural context. Our results have shown that the air relative humidity inside the nests varies considerably less than the environmental air relative humidity, probably because of the humidity sources (nectar and water) and the nest cavity insulation. We also verified that the rate of brood production decrease with the increase of the environmental temperature and is slightly influenced by nest temperature. The developmental time of pupal stage to adult shows an inverse relationship with the rearing temperature. The same occurs with mortality, however it rises dramatically after reaching a temperature threshold. We demonstrated that there are adaptations for cooling the nest in S. depilis, contradicting the current hypothesis that the nesting behavior in thermal insulated cavity would be the main component on the maintenance of temperature in constant and stable levels, supposedly needed to the colony growth and maintenance. Additionally, we suggested that the nest temperature varies considerably (even with the cavity insulation and the actives mechanisms of thermoregulation), however the performance of their activities is regular within a wide range of temperatures, i.e., the stingless bees should support a extent variation of temperatures

Orientador: Leda Gobbo Bueno / Resumo: A otimização da produção de pintainhos, não implica somente na incubação de ovos férteis. Atualmente, as incubadoras necessitam ter alta produtividade de forma sustentável, incluindo o rendimento de incubação de pintainhos saudáveis com altas taxas de sobrevivência no incubatório e o seu desenvolvimento na fase de cria. Dessa forma, o objetivo do presente estudo foi avaliar a influência da manipulação térmica no rendimento de ovos incubáveis de pesos distintos de matrizes leves na última fase embrionária. O experimento foi realizado em incubatório comercial de poedeiras leves, localizado em Birigui –SP. Utilizou-se 1950 ovos de matrizes leves da linhagem comercial Dekalb White®. Os ovos foram classificados entre diferentes tamanhos e alocados em bandejas de incubação. No período de 19 a 21 dias foram utilizados máquinas de nascedouros posicionadas frontalmente ao corredor central. Na primeira máquina manteve-se os valores de temperatura e umidade do ar padrão do incubatório (37,0°C e 60% UR) e na segunda máquina a temperatura foi ajustada para 37,7°C com 60% UR. Os tratamentos se diferenciaram de acordo com tempo de permanência na segunda máquina, e peso dos ovos (G e M) controles T1(G) e T6(M), 1 hora T2(G) e T7(M), 3 horas T3(G) e T8(M), 6 horas T4(G) e T9(M) e 9 horas T5(G) e T10 (M). Após o nascimento as pintainhas foram transferidas para granja de postura comercial, para avaliar o seu desenvolvimento corporal. Para o estudo usou-se o Delineamento Fatorial 2X5. Os dados f... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

Submitted by Jorge Ikefuti Filho (ikefutifilho@msn.com) on 2018-07-19T17:43:12Z No. of bitstreams: 1 005-2018-Jorge Ikefuti Filho 19-07-18.pdf: 2256756 bytes, checksum: 138ed3a16f765780a351d182c74252b2 (MD5) / Approved for entry into archive by Fabio Sampaio Rosas null (fabio@dracena.unesp.br) on 2018-07-19T21:11:48Z (GMT) No. of bitstreams: 1 Ikefuti_filho_j_me_dra.pdf: 2256756 bytes, checksum: 138ed3a16f765780a351d182c74252b2 (MD5) / Made available in DSpace on 2018-07-19T21:11:48Z (GMT). No. of bitstreams: 1 Ikefuti_filho_j_me_dra.pdf: 2256756 bytes, checksum: 138ed3a16f765780a351d182c74252b2 (MD5) Previous issue date: 2018-02-09 / A otimização da produção de pintainhos, não implica somente na incubação de ovos férteis. Atualmente, as incubadoras necessitam ter alta produtividade de forma sustentável, incluindo o rendimento de incubação de pintainhos saudáveis com altas taxas de sobrevivência no incubatório e o seu desenvolvimento na fase de cria. Dessa forma, o objetivo do presente estudo foi avaliar a influência da manipulação térmica no rendimento de ovos incubáveis de pesos distintos de matrizes leves na última fase embrionária. O experimento foi realizado em incubatório comercial de poedeiras leves, localizado em Birigui –SP. Utilizou-se 1950 ovos de matrizes leves da linhagem comercial Dekalb White®. Os ovos foram classificados entre diferentes tamanhos e alocados em bandejas de incubação. No período de 19 a 21 dias foram utilizados máquinas de nascedouros posicionadas frontalmente ao corredor central. Na primeira máquina manteve-se os valores de temperatura e umidade do ar padrão do incubatório (37,0°C e 60% UR) e na segunda máquina a temperatura foi ajustada para 37,7°C com 60% UR. Os tratamentos se diferenciaram de acordo com tempo de permanência na segunda máquina, e peso dos ovos (G e M) controles T1(G) e T6(M), 1 hora T2(G) e T7(M), 3 horas T3(G) e T8(M), 6 horas T4(G) e T9(M) e 9 horas T5(G) e T10 (M). Após o nascimento as pintainhas foram transferidas para granja de postura comercial, para avaliar o seu desenvolvimento corporal. Para o estudo usou-se o Delineamento Fatorial 2X5. Os dados foram submetidos ao teste de hipóteses exato com base na distribuição Binomial para etapa de incubação e algaritimo Neperiano para etapa de crescimento corporal, foi utilizado software Minitab® 17. Como resultados notou-se que para ovos grandes (G), o tempo de permanência de 1 hora (T2), obteve melhores fêmeas comercialmente viáveis e menores índice de mortalidade embrionária na fase tardia e refugagem. Todavia para ovos médios (M) verificou-se melhores resultados com tempo de permanência de 3 e 6 horas (T8 e T9), não houve diferença para etapa de desenvolvimento corporal. / The optimization of the production of chicks does not only imply the incubation of fertile eggs. Currently, incubators need to have high productivity in a sustainable way, including the incubation yield of healthy chicks with high survival rates. Thus, the objective of the present study was to evaluate the influence of thermal manipulation on the yield of hatching eggs of different weights of layer breeds in the last embryonic stage, in the hatchery and its development in the breeding phase.The experiment was carried out in a commercial hatchery of layer breeds, located in Birigui-SP. It used 1950 eggs of layers breeds arrays of commercial line Dekalb White®. The eggs were classified among different sizes and allocated in incubation trays. In the period from 19 to 21 days were used starter machines positioned frontally to the central corridor. In the first machine the temperature and humidity values of the hatchery standard (37,0°C with 60% RH) air were maintained and in the second machine the temperature was adjusted to 37.72 ° C with 60% RH. The treatments were differentiated according to residence time in the second machine, and egg weight (G and M) controls T1 (G) and T6 (M), 1 hour T2 (G) and T7 (M), 3 hours T3 (G) and T8 (M), 6 hours T4 (G) and T9 (M) and 9 hours T5 (G) and T10 (M), After birth the chicks were transferred to the commercial laying nucleus to evaluate their body development. For the study, the 2X5 Factorial Design was used. The data were submitted to the test of exact hypotheses based on the Binomial distribution or incubation stage and Neperian algaritimo for stage of corporal growth, the software Minitab® 17. As results it was noticed that for large eggs (G), the residence time of 1 hour (T2), obtained better commercially viable females and lower embryonic mortality rate in the late phase and shelter. However for medium (M) eggs the best results were observed with residence time of 3 and 6 hours (T8 and T9) there was no difference for the stage of corporal development.

O grande sucesso ecológico dos insetos sociais se deve, em grande parte, ao controle das condições climáticas do ninho, entre as quais é possível destacar a temperatura como uma das variáveis mais importantes. Nas abelhas sem ferrão, um grupo de abelhas eussociais com cerca de 400 espécies distribuidas pela região Neotropical, apesar dos poucos estudos existentes é possível identificar uma grande variedade de estratégias para lidar com a heterogeneidade térmica do ambiente. Em comparação com Apis mellifera (o inseto social mais bem estudado no mundo), é possível verificar, de maneira geral, uma menor capacidade termorregulatória nas abelhas sem ferrão. Portanto, isto coloca as abelhas sem ferrão como importantes modelos que podem permitir a melhor compreensão da evolução da diversidade de estratégias de sucesso nos insetos sociais para lidar com a heterogeneidade térmica. Adicionalmente, as abelhas sem ferrão realizam a polinização, um serviço ambiental chave para a manutenção dos ecossistemas Neotropicais. Dessa forma é necessário conhecer as adaptações térmicas nestes organismos, principalmente as voltadas para as altas temperaturas, para que possam ajudar a prever os impactos das mudanças climáticas nestes organismos. Assim, o objetivo deste estudo foi investigar a capacidade e os mecanismos termorregulatórios em abelhas sem ferrão, bem como alguns aspectos da sensibilidade térmica sob condições de altas temperaturas, usando para isso a espécie Scaptotrigona depilis como organismo modelo. Verificamos que essas abelhas são capazes de resfriar o ninho e para isto, utilizam pelo menos dois mecanismos: a ventilação e a coleta de água para resfriamento evaporativo. Este último comportamento foi observado pela primeira vez em um contexto colonial e natural. Adicionalmente foi verificado que a umidade relativa do ar dentro dos ninhos varia consideravelmente menos que a umidade relativa do ar ambiente, muito provalvemente por conta das fontes de umidade (néctar e água) e do isolamento da cavidade de nidificação. Verificamos que a taxa de construção de células de cria sofre uma diminuição sutil com o aumento da temperatura ambiente e quase nenhuma influência da temperatura do ninho. Finalmente, verificamos que o tempo de desenvolvimento do estágio pupal até o adulto diminui conforme a temperatura de incubação aumenta. Da mesma forma acontece com a mortalidade, porém esta aumenta drasticamente após atingir uma temperatura limite. Demonstramos que existem adaptações claras para o resfriamento do ninho em S. depilis, contradizendo as hipóteses atuais de que a nidificação em cavidades termicamente isoladas seria a principal forma de manter a temperatura em níveis relativamente constantes, supostamente necessários para o crescimento e manutenção da colônia. Adicionalmente, sugerimos que a temperatura dos ninhos varia consideravelmente (mesmo com o isolamento das cavidades e com os mecanismos ativos de termorregulação), porém o desempenho das atividades das abelhas no ninho é regular dentro de uma ampla faixa de temperaturas, i.e., as abelhas sem ferrão devem suportar uma ampla variação de temperaturas. / The great ecological success of the social insects is due, in large part, to their capacity of nest climate control, which it is possible to highlight the temperature as one of the most important variable. The stingless bees, a megadiverse group of eusocial bees with about 400 species on the Neotropical zone, show a great variety of strategies to deal with the thermal heterogeneity of the environment. Compared to Apis mellifera, (the social insect better studied in the world), it is possible to verify in general, that stingless bees have a low thermoregulatory capacity. Because of that different capacity and other biological features, stingless bees are excellent models to test hypothesis that focus on the evolution of diversity of strategies to deal with thermal heterogeneity in social insects and the consequent success in this group. Additionally, stingless bees are responsible for the pollination of an extensive number of vegetal species, which is a key environmental service to the maintenance of the tropical ecosystems. So, knowing their thermal adaptations, mainly the related to high temperatures, is indispensable in this moment, yet this knowledge will help to prevent the impact of global climate changes on this organisms. Thus, the aim of this study was to investigate the mechanisms and the thermoregulatory capacity in stingless bees, as well as some aspects of thermal sensibility under high temperature conditions, using the specie Scapotrigona depilis as model organism. We verified that the specie is capable of cool their nests and, for that, use at least two mechanisms: ventilation and water collection for evaporative cooling. This last behavior was observed for the first time in a colonial and natural context. Our results have shown that the air relative humidity inside the nests varies considerably less than the environmental air relative humidity, probably because of the humidity sources (nectar and water) and the nest cavity insulation. We also verified that the rate of brood production decrease with the increase of the environmental temperature and is slightly influenced by nest temperature. The developmental time of pupal stage to adult shows an inverse relationship with the rearing temperature. The same occurs with mortality, however it rises dramatically after reaching a temperature threshold. We demonstrated that there are adaptations for cooling the nest in S. depilis, contradicting the current hypothesis that the nesting behavior in thermal insulated cavity would be the main component on the maintenance of temperature in constant and stable levels, supposedly needed to the colony growth and maintenance. Additionally, we suggested that the nest temperature varies considerably (even with the cavity insulation and the actives mechanisms of thermoregulation), however the performance of their activities is regular within a wide range of temperatures, i.e., the stingless bees should support a extent variation of temperatures

Genome-wide studies are prone to false positives due to inherently low priors and statistical power. One approach to ameliorate this problem is to seek validation of reported candidate genes across independent studies: genes with repeatedly discovered effects are less likely to be false positives. Inversely, genes reported only as many times as expected by chance alone, while possibly representing novel discoveries, are also more likely to be false positives. We show that, across over 30 genome-wide studies that reported Drosophila and Daphnia genes with possible roles in thermal adaptation, the combined lists of candidate genes and orthologous groups are rapidly approaching the total number of genes and orthologous groups in the respective genomes. This is consistent with the expectation of high frequency of false positives. The majority of these spurious candidates have been identified by one or a few studies, as expected by chance alone. In contrast, a noticeable minority of genes have been identified by numerous studies with the probabilities of such discoveries occurring by chance alone being exceedingly small. For this subset of genes, different studies are in agreement with each other despite differences in the ecological settings, genomic tools and methodology, and reporting thresholds. We provide a reference set of presumed true positives among Drosophila candidate genes and orthologous groups involved in response to changes in temperature, suitable for cross-validation purposes. Despite this approach being prone to false negatives, this list of presumed true positives includes several hundred genes, consistent with the “omnigenic” concept of genetic architecture of complex traits.

Environmental gradients exist at global and local scales and the variable conditions they encompass allow the coexistence of different microbial assemblages. Studying gradients and the selection forces they enclose can reveal the spatial succession and interactions of microorganisms and, therefore, how they are assembled in functionally stable communities. By combining high-throughput sequencing technology and laboratory experimental approaches, I investigated the factors that influence the microbial community assemblages in two types of environmental gradients in the Red Sea. I have studied the communities in the chemoclines occurring at the transition zones along the interfaces between seawater and the Deep Hypersaline Anoxic Brines (DHABs) at the bottom of the Red Sea. Across these chemoclines salinity increases of 5-10 times respect to the overlying seawater. I compared the microbial community diversity and metabolisms in the chemoclines of five different DHABs, finding different microbial community compositions due to the different DHABs characteristics, but the same succession of metabolisms along the five interfaces. From the Suakin Deep brine, I assembled the genome of a novel bacterial phylum and revealed the metabolic features that allow this organism to cope with the challenging variable conditions along the chemocline. In an alternative environmental system, I studied the effect of different thermal regimes on the microbiome of coastal sediment exposed to different yearly ranges of temperature variation. Sediment bacterial communities living under larger temperature variations are more flexible and can grow under a larger range of thermal conditions than communities experiencing narrower temperature ranges. My results highlight the large metabolic flexibility of microorganisms and their capacity to efficiently self-organize in complex functional assemblages under extreme ranges of environmental conditions.