25 research outputs found
Ecological drivers of helminth infection patterns in the Virunga Massif mountain gorilla population
The Virunga Massif mountain gorilla population has been periodically monitored since the early 1970s, with gradually increasing effort. The population declined drastically in the 1970s, but the numbers stabilized in the 1980s. Since then, the population has been steadily increasing within their limited habitat fragment that is surrounded by a dense human population. We examined fecal samples collected during the Virunga 2015–2016 surveys in monitored and unmonitored gorilla groups and quantified strongylid and tapeworm infections using egg counts per gram to determine environmental and host factors that shape these helminth infections. We showed that higher strongylid infections were present in gorilla groups with smaller size of the 500-m buffered minimum-convex polygon (MCP) of detected nest sites per gorilla group, but in higher gorilla densities and inhabiting vegetation types occurring at higher elevations with higher precipitation and lower temperatures. On the contrary, the impact of monitoring (habituation) was minor, detected in tapeworms and only when in the interaction with environmental variables and MCP area. Our results suggest that the Virunga mountain gorilla population may be partially regulated by strongylid nematodes at higher gorilla densities. New health challenges are probably emerging among mountain gorillas because of the success of conservation efforts, as manifested by significant increases in gorilla numbers in recent decades, but few possibilities for the population expansion due to limited amounts of habitat
Bird tolerance to humans in open tropical ecosystems
AbstractAnimal tolerance towards humans can be a key factor facilitating wildlife–human coexistence, yet traits predicting its direction and magnitude across tropical animals are poorly known. Using 10,249 observations for 842 bird species inhabiting open tropical ecosystems in Africa, South America, and Australia, we find that avian tolerance towards humans was lower (i.e., escape distance was longer) in rural rather than urban populations and in populations exposed to lower human disturbance (measured as human footprint index). In addition, larger species and species with larger clutches and enhanced flight ability are less tolerant to human approaches and escape distances increase when birds were approached during the wet season compared to the dry season and from longer starting distances. Identification of key factors affecting animal tolerance towards humans across large spatial and taxonomic scales may help us to better understand and predict the patterns of species distributions in the Anthropocene.</jats:p
Changing roles of propagule, climate, and land use during extralimital colonization of a rose chafer beetle
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Changing roles of propagule, climate and land use during extralimital colonization of a rose chafer beetle
Regardless of their ecosystem functions, some
insects are threatened when facing environmental changes
and disturbances, while others become extremely successful.
It is crucial for successful conservation to differentiate factors
supporting species
’
current distributions from those triggering
range dynamics. Here, we studied the sudden extralimital
colonization of the rose chafer beetle,
Oxythyrea funesta
,in
the Czech Republic. Specifically, we depicted the range ex-
pansion using accumulated historical records of first known
occurrences and then explained the colonization events using
five transformed indices depicting changes in local propagule
pressure (LPP), climate, land use, elevation, and landscape
structure. The slow occupancy increase of
O. funesta
before
1990 changed to a phase of rapid occupancy increase after
1990, driven not only by changes in the environment (climate
and land use) but also by the spatial accumulation of LPP.
Climate was also found to play a significant role but only
during the niche-filling stage before 1990, while land use
became important during the phase of rapid expansion after
1990. Inland waters (e.g., riparian corridors) also contributed
substantially to the spread in the Czech Republic. Our method
of using spatially transformed variables to explain the coloni-
zation events provides a novel way of detecting factors trig-
gering range dynamics. The results highlight the importance
of LPP in driving sudden occupancy increase of extralimital
species and recommend the use of LPP as an important
predictor for modeling range dynamics
První experimenty s automatickými opravami prozodických anotací rozsáhlých řečových korpusů
Většina moderních systémů pro syntézu řeči využívají k naučení nového hlasu rozsáhlé řečové korpusy. Tyto korpusy obvykle obsahují několik hodin řeči namluvené schopnými mluvčími schopnými nahrát takové množství řečových dat v dostatečné kvalitě. Odpovídající fonetická a prozodická anotace nahrávek je potřebná pro vysokou kvalitu syntetické řeči. Pro mnoho jazyků platí, že průběh základní hlasivkové frekvence v posledním prozodickém slově prozodické fráze je charakteristický pro jednotlivé typy vět a strukturu souvětí.Avšak v reálných řečových datech může být tento předpoklad porušen a mohou se objevit i jiné tvary průběhů základní hlasivkové frekvence. To může způsobit nekonzistenci prozódie v syntetické řeči. Tento článek popisuje pokusy s automatickou detekcí prozodického nesouladu v nahraných větách. Pro tento účel je použit jednoduchý GMM klasifikátor. Pokusy byly provedeny na 5 velkých řečových korpusech. Výsledky klasifikace byly úspěšně ověřeny poslechovými testy.Most modern speech synthesis systems utilize large speech corpora to learn new voices. These speech corpora usually contain several hours of speech spoken by talented speakers who are able to record such an amount of speech data in a sufficient quality. An appropriate phonetic and prosodic annotation of the recorded utterances is necessary for a high quality of synthesized speech. For many languages, the pitch shape within the last prosodic word of a phrase is characteristic for particular types of sentences and phrase structure of compound/complex sentences. However in the real data, this formal convention can be breached and a different pitch shape than expected can be present. This can be a source of prosody inconsistency in synthesized speech. This article presents some experiments on automatic detection of prosodic mismatch in recorded utterances. A simple classifier based on GMM was proposed for this task. Experiments were performed on 5 large speech corpora. The classification results were successfully verified by listening tests
Habitat use, but not gene flow, is influenced by human activities in two ecotypes of Egyptian fruit bat (Rousettus aegyptiacus)
Understanding the ecological, behavioural and evolutionary response of organisms to changing environments is of primary importance in a human-altered world. It is crucial to elucidate how human activities alter gene flow and what are the consequences for the genetic structure of a species. We studied two lineages of the Egyptian fruit bat (Rousettus aegyptiacus) throughout the contact zone between mesic and arid Ecozones in the Middle East to evaluate the species' response to the growing proportion of human-altered habitats in the desert. We integrated population genetics, morphometrics and movement ecology to analyse population structure, morphological variation and habitat use from GPS- or radio-tagged individuals from both desert and Mediterranean areas. We classified the spatial distribution and environmental stratification by describing physical–geographical conditions and land cover. We analysed this information to estimate patch occupancy and used an isolation-by-resistance approach to model gene flow patterns. Our results suggest that lineages from desert and Mediterranean habitats, despite their admixture, are isolated by environment and by adaptation supporting their classification as ecotypes. We found a positive effect of human-altered habitats on patch occupancy and habitat use of fruit bats by increasing the availability of roosting and foraging areas. While this commensalism promotes the distribution of fruit bats throughout the Middle East, gene flow between colonies has not been altered by human activities. This discrepancy between habitat use and gene flow patterns may, therefore, be explained by the breeding system of the species and modifications of natal dispersal patterns.This work was funded by the Israel Science Foundation (ISF) Grants ISF‐FIRST 1316/05 and ISF 1259/09, the Grant Agency of the Academy of Sciences of the Czech Republic (IAA 601110905) and the Institutional Research Support grant No. SVV 260 313/2016, the Adelina and Massimo Della Pergolla Chair of Life Sciences and the Minerva Center for Movement Ecology (R.N.), the President of Israel Doctoral Award (D.S.), the Lady Davis Fellowship Trust and the University Pablo de Olavide (A.C‐C)
Uncertainty of Phone Voicing and its Impact on Speech Synthesis
While unit selection speech synthesis is not at the centre of research nowadays, it shows its strengths in deployments where fast fixes and tuning possibilities are required. The key part of this method is target and concatenation costs, usually consisting of features manually designed. When there is a flaw in a feature design, the selection may behave in an unexpected way, not necessarily causing a bad quality speech output. One of such features in our systems was the requirement on the match between expected and real units voicing. Due to the flexibility of the method, we were able to narrow the behaviour of the selection algorithm without worsening the quality of synthesised speech
Data from: Habitat use, but not gene flow, is influenced by human activities in two ecotypes of Egyptian fruit bat (Rousettus aegyptiacus)
Understanding the ecological, behavioral and evolutionary response of organisms to changing environments is of primary importance in a human-altered world. It is crucial to elucidate how human activities alter gene flow and what are the consequences for the genetic structure of a species. We studied two lineages of the Egyptian fruit bat (Rousettus aegyptiacus) throughout the contact zone between mesic and arid ecozones in the Middle East to evaluate the species' response to the growing proportion of human-altered habitats in the desert. We integrated population genetics, morphometrics and movement ecology to analyze population structure, morphological variation and habitat use from GPS- or radio-tagged individuals from both desert and Mediterranean areas. We classified the spatial distribution and environmental stratification by describing physical-geographical conditions and land cover. We analyzed this information to estimate patch occupancy and used an isolation by resistance approach to model gene flow patterns. Our results suggest that lineages from desert and Mediterranean habitats, despite their admixture, are isolated by environment and by adaptation supporting their classification as ecotypes. We found a positive effect of human-altered habitats on patch occupancy and habitat use of fruit bats by increasing the availability of roosting and foraging areas. While this commensalism promotes the distribution of fruit bats throughout the Middle East, gene flow between colonies has not been altered by human activities. This discrepancy between habitat use and gene flow patterns may, therefore, be explained by the breeding system of the species and modifications of natal dispersal patterns