Animal body size often varies systematically along latitudinal gradients, where individuals are either larger or smaller with varying season length. This study examines ecotypic responses by the ...generalist grasshopper Melanoplus femurrubrum (Orthoptera: Acrididae) in body size and covarying, physiologically based life history traits along a latitudinal gradient with respect to seasonality and energetics. The latitudinal compensation hypothesis predicts that smaller body size occurs in colder sites when populations must compensate for time constraints due to short seasons. Shorter season length requires faster developmental and growth rates to complete life cycles in one season. Using a common garden experimental design under laboratory conditions, we examined how grasshopper body size, consumption, developmental time, growth rate and metabolism varied among populations collected along an extended latitudinal gradient. When reared at the same temperature in the lab, individuals from northern populations were smaller, developed more rapidly, and showed higher growth rates, as expected for adaptations to shorter and generally cooler growing seasons. Temperature-dependent, whole organism metabolic rate scaled positively with body size and was lower at northern sites, but mass-specific standard metabolic rate did not differ among sites. Total food consumption varied positively with body size, but northern populations exhibited a higher mass-specific consumption rate. Overall, compensatory life history responses corresponded with key predictions of the latitudinal compensation hypothesis in response to season length.
Invertebrates, ecosystem services and climate change Prather, Chelse M.; Pelini, Shannon L.; Laws, Angela ...
Biological reviews of the Cambridge Philosophical Society,
20/May , Volume:
88, Issue:
2
Journal Article
Peer reviewed
ABSTRACT
The sustainability of ecosystem services depends on a firm understanding of both how organisms provide these services to humans and how these organisms will be altered with a changing ...climate. Unquestionably a dominant feature of most ecosystems, invertebrates affect many ecosystem services and are also highly responsive to climate change. However, there is still a basic lack of understanding of the direct and indirect paths by which invertebrates influence ecosystem services, as well as how climate change will affect those ecosystem services by altering invertebrate populations. This indicates a lack of communication and collaboration among scientists researching ecosystem services and climate change effects on invertebrates, and land managers and researchers from other disciplines, which becomes obvious when systematically reviewing the literature relevant to invertebrates, ecosystem services, and climate change. To address this issue, we review how invertebrates respond to climate change. We then review how invertebrates both positively and negatively influence ecosystem services. Lastly, we provide some critical future directions for research needs, and suggest ways in which managers, scientists and other researchers may collaborate to tackle the complex issue of sustaining invertebrate‐mediated services under a changing climate.
Arbuscular mycorrhizal (AM) fungi are root symbionts that can facilitate plant growth and influence plant communities by altering plant interactions with herbivores. Therefore, AM fungi could be ...critical for the conservation of certain rare plants and herbivores. For example, North American milkweed species are crucial hosts for monarch butterflies (Danaus plexippus). Understanding how mycorrhizal composition affects milkweeds will have direct impacts on the conservation and restoration of both increasingly threatened guilds. We present data from three studies on the effect of AM fungal composition on milkweed growth, latex production, and establishment. First, we grew seven milkweed species with and without a mixture of native mycorrhizal fungi. We assessed how important fungal composition is to milkweed growth and latex production by growing four milkweed species with seven fungal compositions, as single‐species inoculations with four native fungi, a mixture of native fungi, a single commercial fungus of presumably non‐native origin, and noninoculated controls. Finally, we assessed the field establishment of two milkweed species with and without native mycorrhizal inoculation. Milkweed species grew 98% larger and produced 82% more latex after inoculation with native mycorrhizae. Milkweeds were strongly affected by fungal composition; milkweeds were inhibited by commercial fungi (average of −14% growth) and showed variable but positive responses to native fungal species (average of +3% to +38% biomass). Finally, we found that restoration establishment was dependent on inoculation with native fungi and milkweed species. Overall, our findings indicate that some milkweed species (i.e., Asclepias syriaca and A. incarnata) are not responsive to mycorrhizal fungal presence or sensitive to mycorrhizal composition while others are, including endangered species (A. meadii) and species of high conservation value (A. tuberosa). We conclude that the reintroduction of native AM fungi could improve the establishment of desirable milkweed species and should be considered within strategies for plantings for monarch conservation.
This paper focuses on the mapping and rate of spread (ROS) measurement of grass fires using near infrared (NIR) images acquired by a small fixed-wing UAS operating at low altitudes. A new method is ...proposed for spatiotemporal representation of grass fire evolution using time labeled UAS NIR orthomosaics stitched from aerial images collected at varying time stamps over different regions of fire. Furthermore, a novel NIR intensity variance thresholding (IVT) method is proposed for accurate identification and delineation of grass fire fronts based on the obtained NIR mosaics in Digital Numbers (DN). The proposed methods are demonstrated and validated using UAS NIR imagery acquired over a prescribed tallgrass fire in Kansas (around 13 ha.). Three NIR short time-series orthomosaics are generated at a time interval of about two minutes with a spatial registration accuracy of 1.45 m (RMSE). The mean ROS for head, flank, and back tallgrass fires are measured to be 0.28 <inline-formula><tex-math notation="LaTeX">m/s</tex-math></inline-formula>, 0.1 <inline-formula><tex-math notation="LaTeX">m/s</tex-math></inline-formula>, and 0.025 <inline-formula><tex-math notation="LaTeX">m/s</tex-math></inline-formula>.
We show that urban chickadees are faster explorers than forest chickadees. Fast explorers are expected to colonize urban areas more readily but, as of yet, their information gathering strategies have ...not been examined. We find that exploration behaviors of urban individuals are more repeatable, suggesting that urban individuals benefit from diverging more from one another in their behaviour.
Abstract
Urban environments impose novel challenges on animals and, as a result, the behaviors of urban wildlife are changing. In particular, high exploratory tendencies and an ability to gather more information from the environment may facilitate adoption of novel ecological opportunities. As of yet, very few studies have examined if urbanization predicts the way in which animals explore novel environments, or the extent of among-individual variation within these habitats. Here, we assess exploration and its temporal plasticity in black-capped chickadees (Poecile atricapillus; N = 169 individuals, 14 sites) caught along an urban gradient to examine individual differences in exploration and changes in exploration over time and assays under a reaction-norm framework. As predicted, urban birds were significantly faster explorers in a novel environment (contacted more features and moved more), however urbanization did not predict individual differences in the change in exploration over time. Exploration score was moderately repeatable; interestingly, urban chickadees were more repeatable in their initial exploration behaviors, but seemed less repeatable in how they explored over time between assays in comparison to forest birds. Our results support the importance of high exploratory tendencies for urban animals, and suggest, for the first time, that individuals from urban and non-urban habitats differ in the amount of among-individual variation in exploration, and thus urban individuals may benefit from diverging more from one another in their behavior. Future work should examine the extent to which this variation in exploration and plasticity of exploration behaviors represent differences in how individuals gather information from their environment.
Fire metrics such as fire front location and rate of spread (ROS) are critical to understanding the behavior of prescribed fires and wildfires. This paper proposes a new method for prescribed grass ...fire evolution mapping and ROS measurement using multitemporal thermal orthomosaics collected by a small fixed-wing Unmanned Aircraft System (UAS) at low altitudes. The proposed method provides a low-cost, safe, and effective solution for active grass fire monitoring and fire metric measurement in areas that may be challenging for a typical rotor-wing UAS to cover due to endurance and size constraints. The proposed method is demonstrated using a prescribed grass fire data set collected by the KHawk fixed-wing UAS over a 13 ha. Kansas tallgrass prairie field on 8 October 2019. Repeat-pass thermal images collected by the KHawk UAS during about 10 min of the burning were grouped and processed to produce multitemporal orthomosaics with a spatial resolution of about
m and a horizontal position error of about 1.5 m. The resulting orthomosaics were further processed for fire front extraction and the measurement of fire front location and ROS. The head fire ROS of this grass burn was observed to be between 0.2 and 0.4
with a mean value of 0.27
.
The search for predictions of species diversity across environmental gradients has challenged ecologists for decades. The humped-back model (HBM) suggests that plant diversity peaks at intermediate ...productivity; at low productivity few species can tolerate the environmental stresses, and at high productivity a few highly competitive species dominate. Over time the HBM has become increasingly controversial, and recent studies claim to have refuted it. Here, by using data from coordinated surveys conducted throughout grasslands worldwide and comprising a wide range of site productivities, we provide evidence in support of the HBM pattern at both global and regional extents. The relationships described here provide a foundation for further research into the local, landscape, and historical factors that maintain biodiversity.
The search for predictions of species diversity across environmental gradients has challenged ecologists for decades. The humped-back model (HBM) suggests that plant diversity peaks at intermediate ...productivity; at low productivity few species can tolerate the environmental stresses, and at high productivity a few highly competitive species dominate. Over time the HBM has become increasingly controversial, and recent studies claim to have refuted it. Here, by using data from coordinated surveys conducted throughout grasslands worldwide and comprising a wide range of site productivities, we provide evidence in support of the HBM pattern at both global and regional extents. The relationships described here provide a foundation for further research into the local, landscape, and historical factors that maintain biodiversity.
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.
Abstract
Background
increasing numbers of older adults are living with frailty and its adverse consequences. We investigated relationships between diet quality or patterns and incident physical ...frailty in older British men and whether any associations were influenced by inflammation.
Methods
prospective study of 945 men from the British Regional Heart Study aged 70–92 years with no prevalent frailty. Incident frailty was assessed by questionnaire after 3 years of follow-up. Frailty was defined as having at least three of: low grip strength, low physical activity, slow walking speed, unintentional weight loss and feeling of low energy, all based on self-report. The Healthy Diet Indicator (HDI) based on WHO dietary guidelines and the Elderly Dietary Index (EDI) based on a Mediterranean-style dietary intake were computed from questionnaire data and three dietary patterns were identified using principal components analysis: prudent, high fat/low fibre and high sugar.
Results
men in the highest EDI category and those who followed a prudent diet were less likely to become frail top vs bottom category odds ratio (OR) (95% CI) 0.49 (0.30, 0.82) and 0.53 (0.30, 0.92) respectively after adjustment for potential confounders including BMI and prevalent cardiovascular disease. No significant association was seen for the HDI. By contrast those who had a high fat low fibre diet pattern were more likely to become frail OR (95% CI) 2.54 (1.46, 4.40). These associations were not mediated by C-reactive protein (marker of inflammation).
Conclusions
the findings suggest adherence to a Mediterranean–style diet is associated with reduced risk of developing frailty in older people.
PDF
