Quantitative traits are an important part of tardigrade taxonomy for both heterotardigrades and eutardigrades. Because most quantitative traits vary as a function of body size, variation in body size complicates comparisons between individuals or populations. Thus, body size effects must be eliminated in morphometric analysis. Although ratios (size of character/body size) are often used to attempt this, they only work for the specific case of isometry (i.e. when a structure grows proportionally to body size). Ratios do not eliminate body size effects for allometric (disproportionate) growth. In eutardigrades, body size is highly correlated with the length of the rigid buccal tube, whereas body length (BL) is highly variable because of the flexibility of the cuticle and the orientation and coverslip pressure on the specimen. In heterotardigrades, BL is typically used to indicate body size because the thickened dorsal plates provide more rigidity and reliability in measurements. We measured 27 traits in 97 specimens of Paramacrobiotus tonollii (Eutardigrada) and 14 traits in 100 specimens of Echiniscus virginicus (Heterotardigrada) and found that many traits are allometric rather than isometric. Thorpe (1975, Biol J Linn Soc 7:27) provided a normalization technique to eliminate body size effects for any trait regardless of its relationship to body size. Using the data from P. tonollii, we show that Thorpe's size normalization does successfully remove buccal tube length effects (body size effects), while pt indices generally do not. We also demonstrate the effectiveness of Thorpe's normalization in species delineations of Macrobiotus recens and Macrobiotus hufelandi, two species that differ primarily in a few quantitative traits and overall body size in addition to the eggs. Based on these examples, we propose that the allometric exponent (b) and the Y-intercept (a*) of the regression of Thorpe normalized traits versus body size are valuable metrics in tardigrade systematics.

No description available.

Body-size variability results from a variety of extrinsic and intrinsic factors (environmental and biological influences) underpinned by phylogeny. In ostracodes it is assumed that body size is predominantly controlled by ecological conditions, but investigations have mostly focused on local or regional study areas. In this study, we investigate the geographical size variability (length, height, and width) of Holocene and Recent valves of the salinity-tolerant ostracode species Cyprideis torosa within a large geographical area (31◦–51◦ latitude, and 12◦–96◦ longitude). It is shown that distant local size clusters of Cyprideis torosa are framed within two large-scale geographical patterns. One pattern describes the separation of two different size classes (i.e., morphotypes) at around ∼42◦ N. The co-occurrence of both size morphotypes in the same habitats excludes an environmental control on the distribution of the morphotypes but rather could point to the existence of two differentiated lineages. Generally, correlations between valve size and environmental parameters (salinity, geographical positions) strongly depend on the taxonomic resolution. While latitude explains the overall size variability of C. torosa sensu lato (i.e., undifferentiated for morphotypes), salinity-size correlations are restricted to the morphotype scale. Another large-scale pattern represents a continuous increase in valve size of C. torosa with latitude according to the macroecological pattern referred as Bergmann trend. Existing explanations for Bergmann trends insufficiently clarify the size cline of C. torosa which might be because these models are restricted to intraspecific levels. The observed size-latitude relationship of C. torosa may, therefore, result from interspecific divergence (i.e., size ordered spatially may result from interspecific divergence sorting) while environmental influence is of minor importance. Our results imply that geographical body-size patterns of ostracodes are not straightforward and are probably not caused by universal mechanisms. Consideration of phylogenetic relationships of ostracodes is therefore necessary before attempting to identify the role of environmental controls on body size variability.

An amphibian's life history includes patterns such as growth, development, and reproduction. These life history traits are essential to the fundamental understanding of population dynamics. Despite the importance of life history traits, key knowledge gaps still exist, hindering key information on birth/death rates, age/size at sexual maturity, size at metamorphosis, and clutch sizes for amphibians. Moreover, these life patterns can vary due to environmental conditions such as temperature and food availability, further emphasizing the importance of knowledge of species demographics. In this study, I aimed to investigate the growth of young-of-the-year and juvenile plethodontid salamanders with different life cycles, Plethodon cinereus (direct development) and Eurycea cirrigera (metamorphosis). Specifically, I was interested in examining the response of growth trajectories to different temperatures and food availability. I hypothesized that salamanders in the high-temperature treatment will grow faster initially but will be smaller at the conclusion of the experiment, while salamanders in the low-temperature treatment will grow slower initially but will be larger at the end of the experiment. To investigate the interaction between body size and environmental conditions, I exposed both species of salamanders to a factorial design, with two food treatments crossed with two temperature treatments. To analyze the data, I used a generalized additive mixed model (GAMM). The study revealed distinct growth patterns for both species of salamanders. P. cinereus experienced linear growth throughout the duration of the study, whereas E. cirrigera displayed non-linear growth (Throughout the experiment, salamander experienced a decrease in total length and mass). The results of the GAMM did not support my hypothesis for P. cinereus. However, the GAMM results did provide support for my hypothesis in the case of E. cirrigera under high food availability treatment. Furthermore, salamanders with limited food availability in both experiments grew at a slower rate. Forecasting the impacts of climate change on salamander populations is complex and will require the understanding of habitat quality and climate factors. / Master of Science / With the threats of climate change, habitat fragmentation, and disease looming, it's crucial we begin to understand amphibian life history traits, which includes the patterns of growth, development, and reproduction. These life history traits can vary due to environmental conditions and are essential to the fundamental understanding of population size and structure. Despite the importance of life history traits, information on amphibian birth/death rates, age/size at sexual maturity, size at metamorphosis, and clutch sizes are unknown, further emphasizing the importance of understanding species demographics. In this study, I investigated the growth of young-of-the-year and juvenile individuals of two plethodontid salamander species: eastern red-backed salamander and the southern two-lined salamander. These species exhibit two different life strategies. The eastern red-backed salamander is a fully terrestrial direct developing salamander without a distinct metamorphic stage, experiencing gradual growth without major morphological changes. However, the southern two-lined salamander semi aquatic salamander that goes through metamorphosis (Undergoes an aquatic larval stage but transitions to a terrestrial salamander), experiencing major morphological and physiological changes. I investigated the growth response of these two species of salamanders when exposed to different temperatures and when food availability varied from high to low. I hypothesized that salamanders in the high-temperature treatment will grow faster but be smaller at the conclusion of the experiment. While salamanders in the low-temperature treatment would grow slower but be larger at the end of the experiment. To understand the interaction between body size and environmental conditions, I exposed both species of salamanders to a 2x2 factorial experiment design that consisted of 2 food treatments and 2 temperature treatments. To analyze the results, I used a generalized additive mixed model. The results of the study indicated that both species of salamander differed in growth. The eastern red-backed salamander demonstrated linear growth throughout the experiment, while the southern two-lined salamander exhibited non-linear growth (During the experiment, salamanders experienced a decrease in total length and mass). However, the results of the eastern red-backed salamander did not support my hypothesis. Conversely, when food availability was high enough, the results supported my hypothesis for the southern two-lined salamander. Moreover, salamanders exposed to limited food availability in both experiments experienced a decrease in growth rates. Forecasting the impacts of climate change on salamander populations is complex and will require comprehension and insight to habitat quality and climate variables.

No description available.

The biomass size spectrum - the power-law scaling relationship between average individual size and total biomass - has often been studied in lake and marine ecosystems, but rarely in lotic systems. The objective of this study was to test for characteristic biomass spectra in small temperate streams. Seasonal fish and macroinvertebrate data, including population abundance and biomass estimates, were collected in three wadeable, southern West Virginia streams from October 2013 to May 2015. Fish abundances were estimated with 3-pass electrofishing (depletion) surveys and individuals were weighed in the field. Macroinvertebrates were collected with a Hess sampler and returned to the lab for identification to the lowest practical level (usually genus). Published length-mass regressions were then used to estimate individual mass. All size spectra relationships (linear regression of log-log data) were highly significant (p<0.001). Size spectra intercepts were variable and may reflect seasonal differences in fish and invertebrate densities. Size spectra slopes were more consistent, with a mean slope of approximately -0.73, suggesting a common scaling relationship between stream consumers at differing trophic levels.

Ecological network theory has developed from studies of static, binary trophic relationships to the analysis of quantitative, dynamic communities consisting of multiple link-types. Particularly, work has focused on the dynamic nature of ecological networks, which maintains stability in complex communities. However, there are few in situ network-level studies of the determinants of temporal and spatial variation in community structure. This thesis utilises data from a 10-year study of a host-parasitoid network and a collaborative study in an applied ecological setting to identify individual level factors important to network structure. The work aims towards an empirical, predictive framework linking adaptive foraging behaviour to ecological network structure. The results show that condition-dependent foraging behaviours structure host-parasitoid networks. The realised niches of the studied parasitoid species were generally biased towards larger host species and condition-dependent sex ratio allocation increased the likelihood that females would eclose from relatively larger hosts and males from relatively smaller hosts, which resulted in sex ratios deviating from Hamiltonian (50:50) predictions. Further, both of these aspects of behaviour are plastic, where parasitoid behaviour responded to environmental heterogeneity. Particularly, host preference behaviour conformed to an egg-/time-limitation framework, where the size dependency of the behaviour is greater when individuals have a greater likelihood of being egg-limited. Both the size-dependency and the plasticity of these behaviours differed significantly between secondary parasitoid species. This species identity effect interacted with landscape heterogeneity, which may explain some inter- and intra-specific variation in network structure. With respect to applied ecology, the results show that the benefits of natural vegetation for pest control are dependent upon the dispersal capabilities and the diet breadth of the pest and its natural enemies. The findings are evaluated towards a predictive framework for understanding the effects of future climate change on community structure and stability. We consider this framework in terms of applied ecology, particularly pest control ecosystem services provided by natural vegetation in an agricultural environment. The synergistic nature of the multiple determinants of network structure found in this thesis suggest that future studies should focus on the whole network, which is not necessarily the sum of its parts.

Master of Science / Department of Biology / Anthony Joern / Temperature and food quality vary across broad latitudinal gradients, greatly affecting performance by insect herbivores. The contribution of each varies latitudinally so that geographically distinct populations are challenged by differences in nutritional needs and energetic demands. While there has been extensive work studying diet selectivity and nutritional ecology of insect herbivores, few studies have focused on how insect herbivores adapt across such vast environmental gradients. The generalist-feeding grasshopper, Melanoplus femurrubrum (DeGreer), has a broad geographic range that extends across much of North America, making this species ideal for comparative investigations of intrinsic performance responses to extensive but predictable patterns of environmental variation. I compared responses by six populations collected from populations located from Texas to North Dakota (USA) using a common garden experimental design to investigate clinal responses in grasshopper performance. I examined responses in: (1) body size, (2) thermoregulation and adaptive coloration, (3) developmental and growth rates, (4) metabolic rates, (5) total consumption and rates, (6) diet ratio selection, and (7) digestive processing efficiencies across the latitudinal gradient. Grasshopper body size followed the Converse Bergmann’s Rule with decreasing body size as latitude increased. Temperature influenced all other responses, but responses to diet were not always significant or directional. Latitudinal trends for development and growth rates were observed but mass-specific metabolic rates were similar for all populations. Total consumption was body size dependent but independent of diet type. Mass-specific consumption varied but no single directional trend was detected. There was a shift in carbohydrate-biased diet preference at low latitude toward protein-biased diet ratios at higher latitudes, suggesting adaptations to different energetic demands by these populations. However, post-ingestive (digestive) efficiencies demonstrated variable responses with northern populations observing highest efficiencies for some indices but not all. Overall, this research documents phenotypic plasticity to environmental variability to some degree for digestive efficiencies, but ecotypic responses in body size and diet preference among M. femurrubrum populations were observed.

A compreensão da relação entre ventilação, troca gasosa e mecânica ventilatória é de vital importância na busca do entendimento do funcionamento do sistema respiratório. Ao longo do desenvolvimento animal, mudanças no tamanho corpóreo necessitam de reajustes na relação entre seus componentes em nível estrutural e funcional. O tamanho corporal, além de outros fatores, é um agente de influência em variáveis relacionadas ao sistema respiratório em vertebrados. O conhecimento sobre o funcionamento do sistema respiratório em répteis é restrito a algumas espécies, portanto, o presente trabalho teve como objetivo analisar o padrão ventilatório, troca de gases e a mecânica ventilatória em juvenis e adultos de Chelonoidis carbonarius (Cryptodira: Testudinidae). Os animais (n=10) pesando entre 40 gramas a 2,5 quilogramas aproximadamente e sob a condição de normóxia, foram submetidos à respirometria aberta para determinação do padrão ventilatório, do consumo de oxigênio e da produção de gás carbônico em diferentes temperaturas (15, 25 e 35°C). Os volumes pulmonares, complacência estática, complacência dinâmica, resistência pulmonar e o trabalho mecânico da ventilação foram averiguados em juvenis e adultos nas condições supino, prona e para os pulmões isolados das vísceras, verificando assim a influência dessas condições sobre a mecânica ventilatória do sistema respiratório. Os resultados obtidos apresentaram padrões ventilatórios periódicos em todas as temperaturas estudadas. O volume corrente não apresentou mudanças significativas com o aumento da temperatura, enquanto o aumento da frequência respiratória levou ao acréscimo da ventilação por minuto nas comparações entre 15-35°C. O consumo de oxigênio e a excreção de gás carbônico aumentaram com a temperatura e juvenis apresentaram maiores valores comparado a adultos. Tratando-se da mecânica ventilatória, adultos apresentaram diferença para o volume pulmonar de repouso na comparação entre a posição prona e supino e para o volume pulmonar máximo comparado a posição supino com os pulmões isolados. As complacências estática e dinâmica, juntamente com a resistência, padronizadas pela massa corpórea e pelos volumes pulmonares, demonstraram diferenças ao comparar os pulmões isolados com a posição supino. O trabalho mecânico mostrou ser dependente do volume ao invés da frequência em todas as condições testadas. Os resultados apresentados indicaram que mediante mudanças na ventilação, causada pelo aumento da temperatura, juvenis e adultos de Chelonoidis carbonarius, regularam a ventilação aumentando a frequência respiratória e mantiveram os valores do volume corrente a fim de garantir os níveis de trabalho mecânico. / The understanding of the relationship between ventilation, gas exchange and ventilatory mechanics is of vital importance in the search to understand the functioning of the respiratory system. Throughout animal development, changes in body size need adjustments in the relationship between its components at a structural and functional level. Body size, besides other factors, is an agent of influence in variables related to the respiratory system in vertebrates. The knowledge about the function of the respiratory system in reptiles is restricted to some species, so the present work aimed to analyze ventilatory pattern, gas consumption and respiratory mechanics in juveniles and adults of Chelonoidis carbonarius (Cryptodira: Testudinidae). The animals (n = 10) weighing between 40 grams to approximately 2,5 kilograms and under normoxic conditions, were submitted to open respirometry to determine the ventilatory pattern, the oxygen consumption and the production of carbon dioxide at different temperatures (15, 25 and 35°C). Pulmonary volumes, static compliance, dynamic compliance, pulmonary resistance and work of breathing were investigated in juveniles and adults in supine, prone and isolated lung, thus verifying the influence of these conditions on the ventilatory mechanics of the respiratory system. The obtained results presented periodic ventilatory patterns in all the studied temperatures. The tidal volume did not show significant changes with increased temperature, while the raise in breathing frequency led to greater minute ventilation when comparing 15 and 35°C. Oxygen consumption and carbon dioxide excretion increased with temperature and juveniles presented higher values compared to adults. Regarding mechanics, adults presented a significant difference for resting volume in the comparison between the prone and supine position and for the maximum lung volume compared to the supine position with the isolated lungs. Body mass as well as lung volume standardized static and dynamic compliances and resistance showed significant differences when comparing the isolated lungs with the supine position. The mechanical work was shown to be volume dependent rather than frequency in all tested conditions. The results indicated that through changes in ventilation caused by increasing temperature, juveniles and adults of Chelonoidis carbonarius regulated ventilation by increasing minute ventilation and maintained tidal volume values in order to guarantee levels of work of breathing.

Na presente tese investigamos o papel de alguns dos fatores mais importantes na estruturação da fauna de EPT em riachos. No primeiro capítulo, abordamos os efeitos do tamanho do riacho, do tipo de mesohabitat (corredeira e remanso) e da estação do ano (seca e chuva) sobre a abundância, riqueza e composição de Ephemeroptera, Plecoptera e Trichoptera (EPT). Segundo os nossos resultados, a abundância respondeu de forma significativa às interações entre o tipo de mesohabitat e o tamanho do riacho; e entre estação do ano e o tamanho do riacho. A riqueza foi influenciada significativamente pelo tamanho do riacho. Adicionalmente, tanto o tipo de mesohabitat quanto o tamanho do riacho afetaram significativamente a composição faunística (DCA I). O tipo de mesohabitat pode ser considerado um bom preditor da fauna de EPT, mesmo em um sistema altamente sazonal como é o caso dos riachos aqui estudados. No segundo capítulo, apresentamos equações representativas da relação tamanho corpóreo (comprimento do corpo e largura da cápsula cefálica) para táxons de EPT. Considerando os dados obtidos, recomendamos, sempre que possível, a utilização do comprimento do corpo e apenas as equações com o R2 acima de 0,65, as quais podem ser úteis em trabalhos onde informações gerais sobre a biomassa de EPT são necessárias. Este capítulo serviu de base para o capítulo III. No terceiro capítulo, abordamos os padrões de distribuição de frequência do tamanho corpóreo e a relação entre tamanho corpóreo e abundância de EPT. Os nossos resultados mostraram que independente do riacho, do tipo de mesohabitat e da estação do ano, no geral, as distribuições se encaixaram em uma distribuição normal. Considerando as relações entre o tamanho corpóreo e abundância, os dados de 50% das assembleias de EPT analisadas individualmente se encaixaram numa forma piramidal. Em nenhum dos casos, observamos relações lineares negativas, portanto, os nossos dados discordam da Regra de Equivalência Energética. Nossos resultados sugerem que um único fator (e.g. balanço energético) é insuficiente para explicar a relação tamanho-abundância de EPT em ambientes altamente variáveis como os riachos aqui estudados. / In this thesis we investigate the role of some of the most important factors in structuring EPT fauna in streams. In the first chapter, we discuss the effects of stream size, type of mesohabitat (riffles and pools) and season (rainy and dry) on the abundance, richness and composition of Ephemeroptera, Plecoptera and Trichoptera (EPT). According to our results, the abundance responded significantly to the interactions between mesohabitat type and size of the stream, and between season and size of the stream. Richness was significantly influenced by the size of the stream. Additionally, both the mesohabitat type and size of the stream significantly affected the faunal composition (DCA I). The type of mesohabitat can be considered a good predictor of EPT fauna, even in a highly seasonal system like the streams studied here. In the second chapter, we present equations representing the relative body size (body length and width of head capsule) for EPT taxa. Considering the data obtained, it is recommended, where possible, using the length of the body and only equations with R2 above 0.65, which may be useful when general information on the EPT biomass is necessary. This chapter supported the Chapter III. In third chapter we discuss the patterns of frequency distribution of body size and the relationship between body size and abundance of EPT. Our results show that regardless of the stream, the type of mesohabitat and the season, in general, the data on body size fit the normal distribution. Considering the relations between body size and abundance, the data of 50% of EPT assemblages analyzed individually fit the pyramidal shape. In any case, we observed negative linear relationship, therefore, our data disagree with the Energy Equivalence Rule. Our results suggest that a single factor (e.g. energy balance) is insufficient to explain the relationship between size and abundance of EPT in highly variable environments such as streams studied here.