pinecone/core-2020-05-10-deduplication huggingface dataset:
Discovering hidden biodiversity: the use of complementary monitoring of fish diet based on DNA barcoding in freshwater ecosystems

14 páginas, 4 figuras, 5 tablasEcological monitoring contributes to the understanding of complex ecosystem\ud
functions. The diets of fish reflect the surrounding environment and habitats\ud
and may, therefore, act as useful integrating indicators of environmental status.\ud
It is, however, often difficult to visually identify items in gut contents to species\ud
level due to digestion of soft-bodied prey beyond visual recognition, but new\ud
tools rendering this possible are now becoming available. We used a molecular\ud
approach to determine the species identities of consumed diet items of an\ud
introduced generalist feeder, brown trout (Salmo trutta), in 10 Tasmanian lakes\ud
and compared the results with those obtained from visual quantification of\ud
stomach contents. We obtained 44 unique taxa (OTUs) belonging to five phyla,\ud
including seven classes, using the barcode of life approach from cytochrome\ud
oxidase I (COI). Compared with visual quantification, DNA analysis showed\ud
greater accuracy, yielding a 1.4-fold higher number of OTUs. Rarefaction curve\ud
analysis showed saturation of visually inspected taxa, while the curves from the\ud
DNA barcode did not saturate. The OTUs with the highest proportions of haplotypes\ud
were the families of terrestrial insects Formicidae, Chrysomelidae, and\ud
Torbidae and the freshwater Chironomidae. Haplotype occurrence per lake was\ud
negatively correlated with lake depth and transparency. Nearly all haplotypes\ud
were only found in one fish gut from a single lake. Our results indicate that\ud
DNA barcoding of fish diets is a useful and complementary method for discovering\ud
hidden biodiversity.The project was funded by The Korea\ud
National Long-Term Ecological Research\ud
Project (2013), Galathea 3, Sino-Danish\ud
Centre for Education and Research (SDC) and\ud
Aarhus University (AU).Peer reviewe
Quality and quantity: transitions in antimicrobial gland use for parasite defense

Parasites are a major force in evolution, and understanding how host life history affects parasite pressure and investment in disease resistance is a general problem in evolutionary biology. The threat of disease may be especially strong in social animals, and ants have evolved the unique metapleural gland (MG), which in many taxa produce antimicrobial compounds that have been argued to have been a key to their ecological success. However, the importance of the MG in the disease resistance of individual ants across ant taxa has not been examined directly. We investigate experimentally the importance of the MG for disease resistance in the fungus-growing ants, a group in which there is interspecific variation in MG size and which has distinct transitions in life history. We find that more derived taxa rely more on the MG for disease resistance than more basal taxa and that there are a series of evolutionary transitions in the quality, quantity, and usage of the MG secretions, which correlate with transitions in life history. These shifts show how even small clades can exhibit substantial transitions in disease resistance investment, demonstrating that host–parasite relationships can be very dynamic and that targeted experimental, as well as large-scale, comparative studies can be valuable for identifying evolutionary transitions
Limitation of seedling growth by potassium and magnesium supply for two ectomycorrhizal tree species of a Central African rain forest and its implication for their recruitment

In the ectomycorrhizal caesalpiniaceous groves of southern Korup National Park, the dominant tree species, Microberlinia bisulcata, displays very poor in situ recruitment compared with its codominant, Tetraberlinia bifoliolata. The reported ex situ experiment tested whether availabilities of soil potassium and magnesium play a role. Seedlings of the two species received applications of K and Mg fertilizer in potted native soil in a local shade house, and their responses in terms of growth and nutrient concentrations were recorded over 2 years. Amended soil concentrations were also determined. Microberlinia responded strongly and positively in its growth to Mg, but less to K; Tetraberlinia responded weakly to both. Added Mg led to strongly increased Mg concentration for Microberlinia while added K changed that concentration only slightly; Tetraberlinia strongly increased its concentration of K with added K, but only somewhat its Mg concentration with added Mg. Additions of Mg and K had small but important antagonistic effects. Microberlinia is Mg-demanding and apparently Mg-limited in Korup soil; Tetraberlinia, whilst K-demanding, appeared not to be K-limited (for growth). Added K enhanced plant P concentrations of both species. Extra applied Mg may also be alleviating soil aluminum toxicity, and hence improving growth indirectly and especially to the benefit of Microberlinia. Mg appears to be essential for Microberlinia seedling growth and its low soil availability in grove soils at Korup may be an important contributing factor to its poor recruitment. Microberlinia is highly shade-intolerant and strongly light-responding, whilst Tetraberlinia is more shade-tolerant and moderately light-responding, which affords an interesting contrast with respect to their differing responses to Mg supply. The study revealed novel aspects of functional traits and likely niche-partitioning among ectomycorrhizal caesalps in African rain forests. Identifying the direct and interacting indirect effects of essential elements on tropical tree seedling growth presents a considerable challenge due the complex nexus of causes involved
Postdispersal nepotism in male long-tailed macaques (Macaca fascicularis)

Cooperative behaviors are promoted by kin selection if the costs to the actor are smaller than the fitness benefits to the recipient, weighted by the coefficient of relatedness. In primates, cooperation occurs primarily among female dyads. Due to male dispersal before sexual maturity in many primate species, however, it is unknown whether there are sufficient opportunities for selective tolerance and occasional coalitionary support for kin selection to favor male nepotistic support. We studied the effect of the presence of male kin on correlates of male reproductive success (residence time, duration of high dominance rank) in non-natal male long-tailed macaques (Macaca fascicularis). We found that “related” (i.e., related at the half-sibling level or higher) males in a group have a significantly higher probability to remain in the non-natal group compared to males without relatives. Moreover, males stayed longer in a group when a relative was present at group entry or joined the same group within 3 months upon arrival. Males with co-residing relatives also maintained a high rank for longer than those without. To our knowledge, this is the first demonstration of a potential nepotistic effect on residence and rank maintenance among non-natal males in a social system without long-term alliances
Maternal adjustment or constraint: differential effects of food availability on maternal deposition of macro-nutrients, steroids and thyroid hormones in rock pigeon eggs

In oviparous species like birds, eggs provide the direct environment in which embryos are developing. Mothers may adjust different egg components in different ways in reaction to environmental cues either to adjust offspring development or because of constraints. In this study, we investigated the effects of food quality and quantity before and during egg laying on three different aspects of egg quality: macro-nutrients (egg and yolk mass), androgens (testosterone and androstenedione), and thyroid hormones (3,5,3'-triiodothyronine, T3 and l-thyroxine, T4), using the rock pigeon (Columba livia). As expected, egg and yolk mass were significantly reduced for the eggs laid under the poor-food condition, indicating a maternal trade-off between offspring and self in allocating important resources. We did not find any significant change in yolk testosterone or their within-clutch pattern over the laying sequence. This is consistent with the fact that, in contrast with nutrients, these hormones are not costly to produce, but does not support the hypothesis that they play a role in adjusting brood size to food conditions. In contrast, we found that T3 levels were higher in the egg yolks under the poor-food condition whereas the total T4 content was lower. This change could be related to the fact that iodine, the critical constituent of thyroid hormones, might be a limiting factor in the production of this hormone. Given the knowledge that food restriction usually lead to reduction of circulating T3 levels, our results suggested that avian mothers can independently regulate its concentrations in their eggs from their own circulation. The study demonstrates that environmentally induced maternal effects via the egg can be a result of a combination of constrained resources and unconstrained signals and that thyroid hormones might be an interesting case of both. Therefore, this hormone and the interplay of different maternal effects on the offspring phenotype deserve much more attention.status: publishe
Timing and location of reproduction in African waterfowl: an overview of >100 years of nest records.

The timing and location of reproduction are fundamental elements of reproductive success for all organisms. Understanding why animals choose to reproduce at particular times and in particular places is also important for our understanding of other aspects of organismal ecology, such as their habitat requirements, movement strategies, and biogeography. Although breeding patterns in waterfowl are relatively well documented, most studies are from northern temperate regions and the influences of location and time of year on breeding in Afrotropical ducks (Anatidae) are poorly understood. We outline six alternative (but not mutually exclusive) hypotheses that might explain where and when Afrotropical ducks choose to breed. To explore these hypotheses, we assembled and analyzed a new database of c. 22,000 breeding records for 16 Afrotropical ducks and one introduced Palearctic species (the Mallard Anas platyrhynchos). The full database is available on line as an appendix to this article. We identified five distinct breeding strategies as well as two outliers. Peak breeding for 9 of 16 indigenous duck species occurs during the dry season. We found no evidence for spatial synchrony or spatial autocorrelation in breeding, suggesting a high level of flexibility in waterfowl responses to prevailing conditions in any given year. More intensive analyses of alternative hypotheses are needed, but our initial analysis suggests that the timing of breeding for the majority of Afrotropical ducks is driven by a combination of resource availability and predation risk.NRF-South AfricaDST/NRF Center of Excellence at the Percy FitzPatrick InstituteUniversity of Cape Tow
Quantifying interspecific variation in dispersal ability of noctuid moths using an advanced tethered flight technique

Dispersal plays a crucial role in many aspects of species' life histories, yet is often difficult to measure directly. This is particularly true for many insects, especially nocturnal species (e.g. moths) that cannot be easily observed under natural field conditions. Consequently, over the past five decades, laboratory tethered flight techniques have been developed as a means of measuring insect flight duration and speed. However, these previous designs have tended to focus on single species (typically migrant pests), and here we describe an improved apparatus that allows the study of flight ability in a wide range of insect body sizes and types. Obtaining dispersal information from a range of species is crucial for understanding insect population dynamics and range shifts. Our new laboratory tethered flight apparatus automatically records flight duration, speed, and distance of individual insects. The rotational tethered flight mill has very low friction and the arm to which flying insects are attached is extremely lightweight while remaining rigid and strong, permitting both small and large insects to be studied. The apparatus is compact and thus allows many individuals to be studied simultaneously under controlled laboratory conditions. We demonstrate the performance of the apparatus by using the mills to assess the flight capability of 24 species of British noctuid moths, ranging in size from 12-27 mm forewing length (similar to 40-660 mg body mass). We validate the new technique by comparing our tethered flight data with existing information on dispersal ability of noctuids from the published literature and expert opinion. Values for tethered flight variables were in agreement with existing knowledge of dispersal ability in these species, supporting the use of this method to quantify dispersal in insects. Importantly, this new technology opens up the potential to investigate genetic and environmental factors affecting insect dispersal among a wide range of species
Longer wings for faster springs – wing length relates tospring phenology in a long-distanc e migrant across its range

In migratory birds, morphological adaptations for efficient migratory flight often oppose morphological adaptations for efficient behavior during resident periods. This includes adaptations in wing shape for either flying long distances or foraging in the vegetation and in climate-driven variation of body size. In addition, the timing of migratory flights and particularly the timely arrival at local breeding sites is crucial because fitness prospects depend on site-specific phenology. Thus, adaptations for efficient long-distance flights might be also related to conditions at destination areas. For an obligatory long-distance migrant, the common nightingale, we verified that wing length as the aerodynamically important trait, but not structural body size increased from the western to the eastern parts of the species range. In contrast with expectation from aerodynamic theory, however, wing length did not increase with increasing migration distances. Instead, wing length was associated with the phenology at breeding destinations, namely the speed of local spring green-up. We argue that longer wings are beneficial for adjusting migration speed to local conditions for birds breeding in habitats with fast spring green-up and thus short optimal arrival periods. We suggest that the speed of spring green-up at breeding sites is a fundamental variable determining the timing of migration that fine tune phenotypes in migrants across their range
Community dynamics of nematodes after Larsen ice-shelf collapse in the eastern Antarctic Peninsula

Free-living marine nematode communities of the Larsen B embayment at the eastern Antarctic Peninsula were investigated to provide insights on their response and colonisation rate after large-scale ice-shelf collapse. This study compares published data on the post-collapse situation from 2007 with new material from 2011, focusing on two locations in the embayment that showed highly divergent communities in 2007 and that are characterised by a difference in timing of ice-shelf breakup. Data from 2007 exposed a more diverse community at outer station B.South, dominated by the genus Microlaimus. On the contrary, station B.West in the inner part of Larsen B was poor in both numbers of individuals and genera, with dominance of a single Halomonhystera species. Re-assessment of the situation in 2011 showed that communities at both stations diverged even more, due to a drastic increase in Halomonhystera at B.West compared to relatively little change at B.South. On a broader geographical scale, it seems that B.South gradually starts resembling other Antarctic shelf communities, although absence of the genus Sabatieria and high abundance of Microlaimus still set it apart nine years after the main Larsen B collapse. In contrast, thriving of Halomonhystera at B.West further separates its community from other Antarctic shelf areas
Photographic identification of individuals of a free-ranging, small terrestrial vertebrate

This is an open access article under the terms of the Creative Commons Attribution License, which permits use,\ud
distribution and reproduction in any medium, provided the original work is properly cited.Recognition of individuals within an animal population is central to a range of\ud
estimates about population structure and dynamics. However, traditional methods\ud
of distinguishing individuals, by some form of physical marking, often rely\ud
on capture and handling which may affect aspects of normal behavior. Photographic\ud
identification has been used as a less-invasive alternative, but limitations\ud
in both manual and computer-automated recognition of individuals are\ud
particularly problematic for smaller taxa (<500 g). In this study, we explored\ud
the use of photographic identification for individuals of a free-ranging, small\ud
terrestrial reptile using (a) independent observers, and (b) automated matching\ud
with the Interactive Individual Identification System (I3S Pattern) computer\ud
algorithm. We tested the technique on individuals of an Australian skink in the\ud
Egernia group, Slater’s skink Liopholis slateri, whose natural history and varied\ud
scale markings make it a potentially suitable candidate for photo-identification.\ud
From ‘photographic captures’ of skink head profiles, we designed a multichoice\ud
key based on alternate character states and tested the abilities of observers\ud
— with or without experience in wildlife survey — to identify individuals\ud
using categorized test photos. We also used the I3S Pattern algorithm to match\ud
the same set of test photos against a database of 30 individuals. Experienced\ud
observers identified a significantly higher proportion of photos correctly (74%)\ud
than those with no experience (63%) while the I3S software correctly matched\ud
67% as the first ranked match and 83% of images in the top five ranks. This\ud
study is one of the first to investigate photo identification with a free-ranging\ud
small vertebrate. The method demonstrated here has the potential to be applied\ud
to the developing field of camera-traps for wildlife survey and thus a wide\ud
range of survey and monitoring applications
A tough egg to crack: recreational boats as vectors for invasive goby eggs and transdisciplinary management approaches

Non-native invasive species are a major threat to biodiversity, especially in freshwater ecosystems. Freshwater ecosystems are naturally rather isolated from one another. Nonetheless, invasive species often spread rapidly across water sheds. This spread is to a large extent realized by human activities that provide vectors. For example, recreational boats can carry invasive species propagules as ‘aquatic hitch-hikers’ within and across water sheds. We used invasive gobies in Switzerland as a case study to test the plausibility that recreational boats can serve as vectors for invasive fish and that fish eggs can serve as propagules. We found that the peak season of boat movements across Switzerland and the goby spawning season overlap temporally. It is thus plausible that goby eggs attached to boats, anchors or gear may be transported across watersheds. In experimental trials we found that goby eggs show resistance to physical removal (90mN attachment strength of individual eggs) and stay attached if exposed to rapid water flow (2.8m s-138 for 1h). When exposing the eggs to air, we found that hatching success remained high (&gt;95%) even after eggs had been out of water for up to 24h. It is thus plausible that eggs survive during pick up, within water and overland transport by boats. We complemented the experimental plausibility tests with a survey on how decision makers from inside and outside academia rate the feasibility of managing recreational boats as vectors. We found consensus that an installation of a preventive boat vector management is considered an effective and urgent measure. This study advances our understanding of the potential of recreational boats to serve as vectors for invasive vertebrate species, and demonstrates that preventive management of recreational boats is considered feasible by relevant decision makers in- and outside academia
Trophic overlap between fish and riparian spiders : potential impacts of an invasive fish on terrestrial consumers

Studies on resource sharing and partitioning generally consider species that
occur in the same habitat. However, subsidies between linked habitats, such as
streams and riparian zones, create potential for competition between populations
which never directly interact. Evidence suggests that the abundance of
riparian consumers declines after fish invasion and a subsequent increase in
resource sharing of emerging insects. However, diet overlap has not been investigated.
Here, we examine the trophic niche of native fish, invasive fish, and
native spiders in South Africa using stable isotope analysis. We compared spider
abundance and diet at upstream fishless and downstream fish sites and
quantified niche overlap with invasive and native fish. Spider abundance was
consistently higher at upstream fishless sites compared with paired downstream
fish sites, suggesting that the fish reduced aquatic resource availability to riparian
consumers. Spiders incorporated more aquatic than terrestrial insects in
their diet, with aquatic insects accounting for 45–90% of spider mass. In three
of four invaded trout rivers, we found that the average proportion of aquatic
resources in web-building spider diet was higher at fishless sites compared to
fish sites. The probability of web-building and ground spiders overlapping into
the trophic niche of invasive brown and rainbow trout was as high as 26 and
51%, respectively. In contrast, the probability of spiders overlapping into the
trophic niche of native fish was always less than 5%. Our results suggest that
spiders share resources with invasive fish. In contrast, spiders had a low probability
of trophic overlap with native fish indicating that the traits of invaders
may be important in determining their influence on ecosystem subsidies. We
have added to the growing body of evidence that invaders can have crossecosystem
impacts and demonstrated that this can be due to niche overlap.Table S1. Characteristics of the 12 sites during the month
of sampling.Table S2. Invertebrate resource isotope values and results
of ANOVA’s testing for differences between resources and
sites.Table S3. Carbon and nitrogen stable isotope values of
fish and spiders used in the study.The DST-NRF Centre of Excellence in Invasion
 Biologyhttp://onlinelibrary.wiley.com/journal/10.1002/(ISSN)2045-7758am2017Zoology and Entomolog