Filter Results
4505 results
Explaining variation in life histories remains a major challenge because they are multi-dimensional and there are many competing explanatory theories and paradigms. An influential concept in life history theory is the 'fast-slow continuum', exemplified by mammals. Determining the utility of such concepts across taxonomic groups requires comparison of the groups' life histories in multidimensional space. Insects display enormous species richness and phenotypic diversity, but testing hypotheses like the 'fast-slow continuum' has been inhibited by incomplete trait data. We use phylogenetic imputation to generate complete datasets of seven life history traits in orthopterans (grasshoppers and crickets) and examine the robustness of these imputations for our findings. Three phylogenetic principal components explain 83-96% of variation in these data. We find consistent evidence of an axis mostly following expectations of a 'fast-slow continuum', except that 'slow' species produce larger, not smaller, clutches of eggs. We show that the principal axes of variation in orthopterans and reptiles are mutually explanatory, as are those of mammals and birds. Essentially, trait covariation in Orthoptera, with 'slow' species producing larger clutches, is more reptile-like than mammal-or-bird-like. We conclude that the 'fast-slow continuum' is less pronounced in Orthoptera than in birds and mammals, reducing the universal relevance of this pattern, and the theories that predict it.
Data Types:
  • Software/Code
  • Tabular Data
  • Text
Aim: One aspect that is still poorly explored about the origin and maintenance of Neotropical biodiversity is how the evolutionary dynamics of colonization and differentiation in relation to lowland and highland habitats has impacted lineage formation. Most speciation models for this region have focused on vicariant events, and the need to assess the influence of demographic processes has been recognized only recently. We evaluate if the origin of Andean montane lineages of terciopelo pitvipers is explained by either of two historical processes that represent fundamental phylogeographic mechanisms: differentiation by isolation within the highlands or different dispersal events from the lowlands. Location: Western Ecuador. Taxon: Terciopelo pitvipers (Bothrops asper species complex). Methods: We use genomic data and genetic clustering analyses, evaluation of historical migration between genetic clusters, and demographic model selection to investigate recent diversification events in South America using a vertebrate group rarely explored in phylogeographic studies: tropical Andean snakes. Specifically, the origin of two Ecuadorian montane lineages of terciopelo pitvipers was evaluated given ambiguous phylogenetic relationships with the presumably ancestral Pacific lowland lineage. Results: Discrepancies of evolutionary relationships previously obtained with tree-like methods are resolved through the use of modeling approaches. We found strong support for the independent origin of montane lineages based on topologies inferred by maximum-likelihood trees and modeling approaches that take into account possible gene flow. Main conclusions: Recent large-scale studies have found support for identifying dispersal events as important drivers of diversification in the Neotropical region. We contribute to these ideas by identifying a fine-scale case in a rarely explored group of animals -Andean snakes- in which river valleys acted as an entrance for the upward colonization of montane dry habitats and subsequent ecological diversification.
Data Types:
  • Other
  • Software/Code
  • Geospatial Data
  • Text
  • File Set
Root-feeding Scarabaeidae larvae can pose a serious threat to agricultural and forest ecosystems, but many details of larval ecology are still unknown. We developed an acoustic data analysis method based on active sound production by larvae (i.e. stridulations) for gaining new insights into larval ecology. In a laboratory study, third instar larvae of the Common Cockchafer (Melolontha melolontha) (n = 38) and the Forest Cockchafer (M. hippocastani) (n = 15) kept in soil-filled containers were acoustically monitored for 5 min each, resulting in the first known stridulation recordings for each species. Subsequent continuous monitoring of three M. hippocastani larvae over several hours showed that a single larva could stridulate more than 70 times per hour, and stridulation rates increased drastically with increasing larval abundance. The new fractal dimension-based data analysis method automatically detected audio sections with stridulations and provided a semi-quantitative estimate of stridulation activity. It is the first data analysis method specifically targeting Scarabaeidae larvae stridulations in soils, enabling for the first time non-invasive species-specific pest monitoring.
Data Types:
  • Text
  • File Set
Stocking programs designed to return extirpated species to their historical range have become increasingly prevalent, punctuating the need to better understand the risks posed to recipient ecosystems. Here, we investigated the genetic and biological consequences of an anadromous sockeye salmon (Oncorhynchus nerka) stocking program in Skaha Lake, British Columbia, where substantial levels of hybridization/introgression with the native freshwater resident ecotype (kokanee) have been detected. We genetically-assigned 543 individuals (adult spawners, age-0 juveniles) to estimate stock proportions (pure-stock sockeye/kokanee or hybrid) between 2010 and 2017, with a subset undergoing otolith microchemistry analysis to determine migratory life history and maternal ancestry. Proportion of hybrid spawners varied from 5-20% across sampling years, while hybrid age-0 juveniles remained relatively constant (~11%). Hybrid spawners exhibited intermediate size relative to pure-stocks, with the vast majority being non-anadromous (92%) and of resident maternal ancestry (76%). Our results provide empirical support for previously hypothesized mechanisms of hybridization between O. nerka life-history forms, and underscore the importance of continued monitoring of stocking programs to quantify long-term fitness impacts of introgression and refine management strategies.
Data Types:
  • Text
Temperature is a ubiquitous environmental factor affecting physiological processes of ectotherms. Due to the effects of climate change on global air and water temperatures, predicting the impacts of changes in environmental thermal conditions on ecosystems is becoming increasingly important. This is especially crucial for migratory fish, such as the ecologically and economically vital salmonids, because their complex life histories make them particularly vulnerable. Here, we addressed the question whether temperature affects the morphology of brown trout, Salmo trutta L. spermatozoa. The fertilising ability of spermatozoa is commonly attributed to their morphological dimensions, thus implying direct impacts on the reproductive success of the male producing the cells. We show that absolute lengths of spermatozoa are not affected by temperature, but spermatozoa from warm acclimated S. trutta males have longer flagella relative to their head size compared to their cold acclimated counterparts. This did not directly affect sperm swimming speed, although spermatozoa from warm acclimated males may have experienced a hydrodynamic advantage at warmer temperatures, as suggested by our calculations of drag based on head size and sperm swimming speed. The results presented here highlight the importance of increasing our knowledge of the effects of temperature on all aspects of salmonid reproduction in order to secure their continued abundance.
Data Types:
  • Software/Code
  • Text
1. The majority of bird and bat species are incapable of carrying tags that transmit their position to satellites. Given fundamental power requirements for such communication, burdened mass guidelines, and battery technology, this constraint necessitates the continued use of very high frequency (VHF) radio beacons. As such, efforts should be made to mitigate their primary deficiencies: detection range, localization time, and localization accuracy. 2. The integration of a radio telemetry system with an unmanned aerial vehicle (UAV) could significantly improve the capacity for data collection from VHF tags. We present a UAV-integrated radio telemetry system that relies on open source hardware and software. Localization methods including signal processing, bearing estimation based on principal component analysis, localization techniques, and test results are discussed. 3. Using a low power beacon applicable for bats and small birds, testing showed that the improved vantage of the UAV-radio telemetry system (UAV-RT) provided significantly higher received signal power compared to low level flights (maximum range beyond 1.4 km). Flight testing of localization methods showed median bearing errors between 2.3-6.8 degrees, with localization errors of between 5-14% of the distance to the tag. In a direct comparison to an experienced radio telemetry user, the UAV-RT system provided bearing and localization estimates with 53% less error. 4. This paper introduces the core functionality and use methods of the UAV-RT system, while presenting baseline localization performance metrics. An associated website hosts plans for assembly and software installation. The methods of UAV-RT use for tag detection will be further developed in future works. For both the detection and localization problems, the mobility of a flying asset drastically reduces tracker time requirements. A seven-minute flight would be sufficient to collect five equally spaced bearing estimates over a 1 km transect. The use of a software defined radio on the UAV-RT system will allow for the simultaneous detection and localization of multiple tags.
Data Types:
  • Text
Wildfires drive global biodiversity patterns and affect plant–pollinator interactions, and are expected to become more frequent and severe under climate change. Post‐fire plant communities often have increased floral abundance and diversity, but the effects of wildfires on the ecological process of pollination are poorly understood. Nocturnal moths are globally important pollinators, but no previous study has examined the effects of wildfire on nocturnal pollination interactions. We investigated the effects of wildfire on nocturnal pollen‐transport networks. We analysed the abundance and species richness of moths and flowers, and the structure of these networks, at three burned and three unburned sites in Portugal for two years, starting eight months after a large fire. Nocturnal pollen‐transport networks had lower complexity and robustness following the fire than at nearby unburned sites. Overall, 70% of individual moths carried pollen, and moths were found to be transporting pollen from 83% of the flower species present. Burned sites had significantly more abundant flowers, but less abundant and species‐rich moths. Individual moths transported more pollen in summer at burned sites, but less in winter; however, total pollen transport by the moth assemblage at burned sites was just 20% of that at unburned sites. Interaction turnover between burned and unburned networks was high. Negative effects of fire upon moths will likely permeate to other taxa through loss of mutualisms. Therefore, if wildfires become more frequent under climate change, community resilience may be eroded. Understanding the responses of ecological networks to wildfire can inform management that promotes resilience and facilitates whole‐ecosystem conservation.
Data Types:
  • Tabular Data
  • Text
Aims: As global temperatures rise, the survival of many species may hinge on whether they can shift their climatic niches quickly enough to avoid extinction. Previous analyses among species and populations suggest that species’ niches change far slower than rates of projected climate change. However, it is unclear how quickly niches can change over the timeframe most relevant to global warming (decades instead of thousands or millions of years). Here, we use data from introduced species to assess how quickly climatic niches can change over decadal timescales. Location: Global Methods: We analyze climatic data from 76 reptile and amphibian species introduced into the U.S. We test for a relationship between species climatic-niche values in their native and introduced ranges. We also quantify niche shifts in introduced populations relative to their native ranges and the rate of change associated with these shifts. We then compare these rate estimates to those estimated among species and to projected rates of future climate change. Results: Remarkably, niche shifts in introduced species are roughly a million times faster than niche shifts among species in their native ranges, and roughly ten times faster than rates of projected climate change. Main conclusions: Our results demonstrate that dramatic and rapid niche shifts are possible, although these may be limited in species’ native ranges by biotic interactions and other factors.
Data Types:
  • Other
  • Tabular Data
  • Document
Plant diversity fosters productivity in natural ecosystems. Biodiversity effects might increase agricultural yields at no cost in additional inputs. However, the effects of diversity on crop assemblages are inconsistent, probably because crops and wild plants differ in a range of traits relevant to plant-plant interactions. We tested whether domestication has changed the potential of crop mixtures to over-yield by comparing the performance and traits of major crop species and those of their wild progenitors under varying levels of diversity. We found stronger biodiversity effects in mixtures of wild progenitors, due to larger selection effects. Variation in selection effects was partly explained by within-mixture differences in leaf size. Our results indicate that domestication might disrupt the ability of crops to benefit from diverse neighbourhoods via reduced trait variance. These results highlight potential limitations of current crop mixtures to over-yield and the potential of breeding to re-establish variance and increase mixture performance.
Data Types:
  • Text
1. Satellite-based technologies that track individual animal movements enable the mapping of their spatial and temporal patterns of occurrence. This is particularly useful in poorly studied or remote regions where there is a need for the rapid gathering of relevant ecological knowledge to inform management actions. One such region is East Asia, where many intertidal habitats are being degraded at unprecedented rates and shorebird populations relying on these habitats show rapid declines. 2. We examine the utility of satellite tracking to accelerate the identification of coastal sites of conservation importance in the East Asian-Australasian Flyway. In 2015–2017 we used solar-powered satellite transmitters to track the migration of 32 great knots (Calidris tenuirostris), an ‘Endangered’ shorebird species widely distributed in the Flyway and fully dependent on intertidal habitats for foraging during the non-breeding season. 3. From the great knot tracks, a total of 92 stopping sites along the Flyway were identified. Surprisingly, 63% of these sites were not known as important shorebird sites before our study; in fact, every one of the tracked individuals used sites that were previously unrecognized. 4. Site knowledge from on-ground studies in the Flyway is most complete for the Yellow Sea and generally lacking for Southeast Asia, Southern China, and Eastern Russia. 5. Policy implications: Satellite tracking highlighted coastal habitats that are potentially important for shorebirds but lack ecological information and conservation recognition, such as those in Southern China and Southeast Asia. At the same time, the distributional data of tracked individuals can direct on-ground surveys at the lesser-known sites to collect information on bird numbers and habitat characteristics. To recognize and subsequently protect valuable coastal habitats, filling knowledge gaps by integrating bird tracking with ground-based methods should be prioritized.19-Jun-2019
Data Types:
  • Document
  • Text
8