scholarly journals Australian corticolous myxomycetes: models of distribution and development

2019 ◽  
Vol 67 (8) ◽  
pp. 617 ◽  
Author(s):  
Peter Wellman
Keyword(s):  
Population Decline ◽  
Common Species ◽  
Growth Cycle ◽  
Population Increase ◽  
Arid Areas ◽  
Species Assemblage ◽  
Population Declines ◽  
Moist Chamber ◽  
Linear Plot ◽  
Chamber Technique

This paper presents an integrated model of the variation over a continental landmass of myxomycetes, a single-celled organism in the phylum Amoebozoa. Bark samples were collected on long traverses across Australia, and cultivated in Petri dishes by the moist chamber technique to obtain large assemblages of common species. The results of this survey and previous surveys are consistent with there being four major myxomycete assemblages: Tropical, Northern Arid, Southern Arid and Temperate. Where mapped, these species assemblage regions are consistent with the Australian phytogeographical regions. The myxomycetes differ between arid and non-arid areas; the arid areas have slightly higher productivity per wetting event, with members of the Physarales and Liceales relatively important and the Stemonitidales, Trichiales and Cribrariales less important. When the bark samples are placed in a moist culture there is a myxomycete growth cycle and then the population declines to resting phases. The population increase during a growth phase can be modelled by a linear plot of log(abundance) against species rank, where abundance is total harvested spore volume of a species. The population decline appears to be linear from two weeks after watering, declining to negligible activity 4 weeks after watering.

Myxomycetes on the bark of Banksia attenuata and B. menziesii (Proteaceae)

2006 ◽  
Vol 54 (4) ◽  
pp. 357 ◽  
Author(s):  
C. C. Jordan ◽  
M. H. Brims ◽  
E. J. Speijers ◽  
E. M. Davison
Keyword(s):  
Moisture Content ◽  
New Records ◽  
Common Species ◽  
Species Assemblage ◽  
Decomposition Level ◽  
Moist Chamber ◽  
Relative Moisture Content ◽  
Relative Moisture ◽  
Banksia Attenuata ◽  
Chamber Technique

Myxomycetes on the bark of dead Banksia attenuata and B. menziesii from the Perth metropolitan area of Western Australia were surveyed by the moist chamber technique, to determine whether the flora was similar on both hosts and what were the most important variables that determined the distribution of the most common species. Twenty-seven species of myxomycetes were recovered, including six new records for Australia (Comatricha rigidireta, Echinostelium elachiston, Paradiacheopsis cf. cribrata, P. rigida, Stemonitopsis amoena and S. cf. hyperopta). Members of the order Stemonitales comprised the largest number of species, whereas members of the Liceales occurred on the most bark pieces. The most common species were Licea kleistobolus, Echinostelium minutum, Comatricha elegans, Cribraria minutissima and Paradiacheopsis fimbriata. Overall, B. menziesii and B. attenuata had very similar myxomycete productivity, diversity and species assemblage, as did the tops and bottoms of the logs. It was concluded that they provided very similar microhabitats for myxomycetes. Both pH and the relative moisture content of the bark had an effect on myxomycete productivity. Bark decomposition level, pH and bark surface (top or bottom) were the most important variables determining the distribution of the most common myxomycete species.

Conservation biology of marine fishes: perceptions and caveats regarding assignment of extinction risk

2001 ◽  
Vol 58 (1) ◽  
pp. 108-121 ◽  
Author(s):  
Jeffrey A Hutchings
Keyword(s):  
Population Size ◽  
Extinction Risk ◽  
Population Decline ◽  
Empirical Support ◽  
Marine Fishes ◽  
Marine Biodiversity ◽  
Population Declines ◽  
High Fecundity ◽  
Reproductive Rates ◽  
Biological Extinction

Quantitative criteria used to assign species to categories of extinction risk may seriously overestimate these risks for marine fishes. Contemporary perception is that marine fishes may be less vulnerable to extinction than other taxa, because of great natural variability in abundance, high fecundity, rapid population growth, and an intrinsically high capability of recovering from low population size. Contrary to perception, however, there appears to be generally little theoretical or empirical support for the hypotheses that marine fish are more likely to experience large reductions in population size, to produce unusually high levels of recruitment, to have higher reproductive rates, or to recover more rapidly from prolonged population declines than nonmarine fishes. Although existing population-decline criteria may not accurately reflect probabilities of biological extinction, they do appear to reflect the converse-population recovery. Insufficient support for contemporary perceptions of their susceptibility to extinction, coupled with caveats associated with the assignment of extinction risk, suggest that significant increases in the population-decline thresholds used to assign marine fishes to at-risk categories would be inconsistent with a precautionary approach to fisheries management and the conservation of marine biodiversity.

Fates and movements of meadow voles (Microtus pennsylvanicus) following a population decline

1988 ◽  
Vol 66 (2) ◽  
pp. 323-328 ◽  
Author(s):  
Steve Mihok ◽  
Todd Lawton ◽  
Bill Schwartz
Keyword(s):  
Direct Evidence ◽  
Population Decline ◽  
Microtus Pennsylvanicus ◽  
Population Declines ◽  
Severe Winter ◽  
Meadow Voles ◽  
Small Areas ◽  
Small Mustelids ◽  
Winter Population

The movements of 24 meadow voles were monitored with radiotelemetry during summer 1985 near Pinawa, Manitoba, to ascertain fates following a severe winter population decline. Low breeding season survival of 22% per month resulted in the persistence of low numbers through spring 1986. Despite densities of only a few individuals per hectare, voles were captured in both meadows and forests. Some voles first caught in forests (mostly males) moved over large areas (up to 4 ha), including both meadow and forest habitat. In contrast, voles captured in meadows were sedentary, often confining their movements to small areas of 0.1–0.2 ha. Radiotransmitters were recovered from 18 of 19 voles that died during the study. Five voles (28%) appeared to have died in situ; six voles (33%) may have been taken by an unusually clean predator or scavenger. Fates of the remaining voles were uncertain. No direct evidence of predation by small mustelids was found to support the hypothesis that these predators account for the persistence of low density following population declines.

scholarly journals A globally threatened shark, Carcharias taurus, shows no population decline in South Africa

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Juliana D. Klein ◽  
Aletta E. Bester-van der Merwe ◽  
Matthew L. Dicken ◽  
Arsalan Emami-Khoyi ◽  
Kolobe L. Mmonwa ◽  
...  
Keyword(s):  
South Africa ◽  
Census Data ◽  
Demographic History ◽  
Conservation Status ◽  
Population Decline ◽  
Multilocus Genotype ◽  
Population Declines ◽  
Effective Population ◽  
Anthropogenic Pressures ◽  
Carcharias Taurus

Abstract Knowledge about the demographic histories of natural populations helps to evaluate their conservation status, and potential impacts of natural and anthropogenic pressures. In particular, estimates of effective population size obtained through molecular data can provide useful information to guide management decisions for vulnerable populations. The spotted ragged-tooth shark, Carcharias taurus (also known as the sandtiger or grey nurse shark), is widely distributed in warm-temperate and subtropical waters, but has suffered severe population declines across much of its range as a result of overexploitation. Here, we used multilocus genotype data to investigate the demographic history of the South African C. taurus population. Using approximate Bayesian computation and likelihood-based importance sampling, we found that the population underwent a historical range expansion that may have been linked to climatic changes during the late Pleistocene. There was no evidence for a recent anthropogenic decline. Together with census data suggesting a stable population, these results support the idea that fishing pressure and other threats have so far not been detrimental to the local C. taurus population. The results reported here indicate that South Africa could possibly harbour the last remaining, relatively pristine population of this widespread but vulnerable top predator.

scholarly journals Predicting how populations decline to extinction

2011 ◽  
Vol 366 (1577) ◽  
pp. 2577-2586 ◽  
Author(s):  
Ben Collen ◽  
Louise McRae ◽  
Stefanie Deinet ◽  
Adriana De Palma ◽  
Tharsila Carranza ◽  
...  
Keyword(s):  
At Risk ◽  
Extinction Risk ◽  
Mammalian Species ◽  
Local Population ◽  
Population Decline ◽  
Scale Up ◽  
Population Level ◽  
Biological Traits ◽  
Population Declines ◽  
Trend Data

Global species extinction typically represents the endpoint in a long sequence of population declines and local extinctions. In comparative studies of extinction risk of contemporary mammalian species, there appear to be some universal traits that may predispose taxa to an elevated risk of extinction. In local population-level studies, there are limited insights into the process of population decline and extinction. Moreover, there is still little appreciation of how local processes scale up to global patterns. Advancing the understanding of factors which predispose populations to rapid declines will benefit proactive conservation and may allow us to target at-risk populations as well as at-risk species. Here, we take mammalian population trend data from the largest repository of population abundance trends, and combine it with the PanTHERIA database on mammal traits to answer the question: what factors can be used to predict decline in mammalian abundance? We find in general that environmental variables are better determinants of cross-species population-level decline than intrinsic biological traits. For effective conservation, we must not only describe which species are at risk and why, but also prescribe ways to counteract this.

Myxomycetes biodiversity in Gaziantep Province (Turkey) with four new records

Phytotaxa ◽  
2021 ◽  
Vol 478 (1) ◽  
pp. 105-118
Author(s):  
HAYRİ BABA ◽  
FATMA GÜNDOĞDU ◽  
MUSTAFA SEVİNDİK
Keyword(s):  
New Records ◽  
Substrate Material ◽  
Tree Bark ◽  
Bearing Material ◽  
Moist Chamber ◽  
Humid Environment ◽  
Animal Material ◽  
Live Tree ◽  
Chamber Technique

Myxomycetes were cultured in moist chambers using substrate material collected in Gaziantep province, Turkey, during 2017–2019. Fruit bodies of wild myxomycetes were collected at ten locations. Rotten or live tree bark, leaves, debris, vegetable, and animal material, which were considered likely to contain spores, were also collected. Natural samples were immediately dried, and potential spore-bearing material was kept in a warm and humid environment with the moist chamber technique. A total of 537 samples were studied and 203 myxomycetes isolates were obtained, 33 of which were natural samples, 76 were obtained with the moist chamber technique and 94 were obtained both naturally and with the moist chamber technique in the laboratory. Six orders, 9 families, 16 genera and 42 species were identified in 3 subclasses. All species were new in Gaziantep province and four myxomycetes were identified as new records in Turkey; Didymium atrichum Henney & Alexop., Didymium serpula Fr., Craterium obovatum Peck and Physarum bivalve Pers. were added to the Turkish mycota.

Population decline of the Japanese sardine, Sardinops melanostictus, in relation to sea surface temperature in the Kuroshio Extension

1999 ◽  
Vol 56 (6) ◽  
pp. 973-983 ◽  
Author(s):  
Masayuki Noto ◽  
Ichiro Yasuda
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Population Size ◽  
Kuroshio Extension ◽  
Population Decline ◽  
Sea Surface ◽  
Population Increase ◽  
Japanese Sardine ◽  
The Relationship ◽  
The Kuroshio

The relationship between the population size of the Japanese sardine, Sardinops melanostictus, and sea surface temperature (SST) from 1979 to 1994 was studied. Significant positive correlations were found between the natural mortality coefficient during the period from the postlarval stage to age 1 and winter-spring SST in the Kuroshio Extension and its southern recirculation area (30-35°N, 145-180°E). That is, higher (lower) SST over the possible migration route corresponded to higher (lower) mortality rate. This result is consistent with the high mortality and low population size for the high-SST period of the 1950's and 1960's and the population increase during the low-SST period of the 1970's and 1980's due to a decrease in mortality. The population decline after 1988 possibly occurred as a result of the abrupt increase in SST since 1988 in the Kuroshio Extension region and suggests a close relationship between interdecadal climate-ocean variability and sardine population size. This may also explain the relationship between biomass size and distribution area.

Predation on toxic cane toads (Bufo marinus) may imperil bluetongue lizards (Tiliqua scincoides intermedia, Scincidae) in tropical Australia

2010 ◽  
Vol 37 (2) ◽  
pp. 166 ◽  
Author(s):  
Samantha J. Price-Rees ◽  
Gregory P. Brown ◽  
Richard Shine
Keyword(s):  
Population Decline ◽  
Bufo Marinus ◽  
Ecological Impacts ◽  
Laboratory Research ◽  
Direct Result ◽  
Population Declines ◽  
Cane Toad ◽  
Lizard Species ◽  
Stochastic Variation ◽  
Tropical Australia

Context. Detecting ecological impacts of invasive species can be extremely difficult. Even major population declines may be undetectable without extensive long-term data if the affected taxon is rare and/or difficult to census, and exhibits stochastic variation in abundance as a result of other factors. Our data suggest such a situation in an iconic Australian reptile species, the bluetongue lizard. Originally restricted to Central and South America, cane toads (Bufo marinus) are rapidly spreading through tropical Australia. Most native predators have no evolutionary history of exposure to the toads’ distinctive chemical defences (bufadienolides), and many varanid lizards, elapid snakes, crocodiles and marsupials have been killed when they have attempted to consume toads. Aims. Scincid lizards have not been considered vulnerable to toad invasion; however, one lineage (the bluetongues, genus Tiliqua) consists of large omnivores that may be affected. Our field and laboratory research aimed to elucidate this concern. Methods. Nightly surveys for bluetongue lizards (Tiliqua scincoides intermedia) and cane toads were conducted along two adjacent roadways on the Adelaide River floodplain of the Northern Territory. Scent discrimination trials in the laboratory assessed lizard responses to chemical cues from three food types (native frogs, cane toads and ‘preferred foods’) by counting tongue-flicks and biting elicited by cotton swabs. A subset of lizards was presented with live toads. Key results. Numbers of bluetongues encountered during standardised field surveys in the Darwin region declined soon after toads arrived, and we have not recorded a single lizard for the last 20 months. In the laboratory, foraging responses of bluetongues were as intense to cane-toad scent as to the scent of native frogs, and many of the lizards we tested attempted to consume toads, and were poisoned as a result. Conclusions and implications. The population decline of bluetongues in this region appears to have been the direct result of fatal ingestion of toxic cane toads. Our studies thus add a scincid lizard species to the list of native Australian predators imperilled by cane-toad invasion, and point to the difficulty of detecting invader impact even for an iconic species in a system subject to detailed survey work.

scholarly journals Population decline and range contraction of the Egyptian Vulture Neophron percnopterus in the Balkan Peninsula

2014 ◽  
Vol 25 (4) ◽  
pp. 440-450 ◽  
Author(s):  
METODIJA VELEVSKI ◽  
STOYAN C. NIKOLOV ◽  
BEN HALLMANN ◽  
VLADIMIR DOBREV ◽  
LAVRENTIS SIDIROPOULOS ◽  
...  
Keyword(s):  
Spatial Scales ◽  
Population Decline ◽  
Balkan Peninsula ◽  
Population Declines ◽  
Egyptian Vulture ◽  
Breeding Grounds ◽  
Conservation Actions ◽  
Causes Of Mortality ◽  
Yugoslav Republic

SummaryThe Egyptian Vulture has been classified as ‘Endangered’ due to a rapid population decline in India and long term declines in Europe and Africa. Although the species has been reported to be declining in Eastern Europe, no quantitative assessment of the magnitude or the causes for population declines are available. We used monitoring data from the Balkan Peninsula to estimate changes in population size and extent of occurrence of Egyptian Vultures between 1980 and 2013. We quantified population trends in three countries (Bulgaria, Greece and the former Yugoslav Republic [FYR] of Macedonia) to assess whether population declines are similar within the Balkan range states. We found a rapid and consistent decline of the Egyptian Vulture population that was largely similar among the three countries (λ = 0.940 in FYR of Macedonia, 0.951 in Bulgaria, 0.920 in Greece). As a consequence of population declines, the breeding range of Egyptian Vultures has contracted and the population in the Balkan Peninsula has fragmented into six subpopulations separated by more than 80 km. Population declines may be driven by factors such as poisoning, electrocution, direct persecution and changes in food availability which operate at large spatial scales and affect birds both on breeding grounds as well as during migration and wintering. Because the relative importance of threats to the survival of Egyptian Vultures are poorly understood, there is a critical need for research into causes of mortality and potential conservation actions that may halt and reverse population declines.

Ticks (Acari: Ixodoidea) of Ethiopia. I. Distribution, ecology and host relationships of species infesting livestock

1981 ◽  
Vol 71 (2) ◽  
pp. 339-359 ◽  
Author(s):  
Rupert G. Pegram ◽  
Harry Hoogstraal ◽  
Hilda Y. Wassef
Keyword(s):  
Common Species ◽  
Domestic Animals ◽  
Arid Areas ◽  
Eastern Ethiopia ◽  
Ornithodoros Savignyi ◽  
Boophilus Decoloratus ◽  
Rhipicephalus Evertsi Evertsi ◽  
The Common ◽  
Host Relationships ◽  
Semi Arid

AbstractIn a survey of adult ticks infesting livestock in Ethiopia, 33 species and subspecies were identified. The distribution and abundance of each are discussed in relation to ecology (altitude, climate and vegetation). Amblyomma variegatum (F.) is the most widespread and abundant tick parasitising cattle. A. cohaerens Dön. is common on cattle in wetter western habitats but is replaced by A. gemma Dön. in drier eastern areas. A. lepidum Dön. occupies intermediate habitats. The distribution of Boophilus decoloratus (Koch) is similar to that of A. variegatum. Hyalomma truncatum Koch and H. marginatum rufipes Koch are both common except in extremely arid and humid zones. H. anatolicum anatolicum Koch, H. anatolicum excavatum Koch, H. dromedarii Koch, H. erythraeum Tonelli-Rondelli, and H. impeltatum Schulze & Schlottke are usually associated with camels in semi-arid areas of eastern Ethiopia. Rhipicephalus evertsi evertsi Neum., R. sanguineus (Latr.) group and R. simus Koch do not display marked ecological preferences. East of the Rift Valley in semi-arid areas below 2000 m, R. pulchellus (Gerst.) is abundant on cattle and camels. R. longicoxatus Neum. and R. pravus Dön. inhabit drier localities, but R. lunulatus Neum. occurs only in wetter western areas. Species taken infrequently were A. nuttalli Dön., A. sparsum Neum., B. annulatus (Say), Haemaphysalis aciculifer Warb., H. leachii (Aud.), H. parmata Neum., H. spinulosa Neum., Hyalomma marginatum marginatum Koch, H. marginatum turanicum Pom., H. punt Hoogst., Kaiser & Pedersen, Ornithodoros savignyi (Aud.), R. longus Neum., R. muhsamae Morel & Vassiliades, and R. senegalensis Koch. The seasonal dynamics of the common species and observations on their relationships to tick-borne diseases of man and domestic animals are discussed.

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