Microbial Characteristics of a Submerged Karst Cave System in Northern Florida

Karst aquifer systems contain submerged caves that act as conduits for subterranean water flow and are subject to rapid surface recharge at points such as sink holes and submerging streams. We examined the microbial communities in six conduits of the Northern Florida Wakulla Springs cave system and in several hydrologically connected surface sinks. Culturable bacteria were assessed using both oligotrophic and copiotrophic media, and specific media for Enterococcus and Escherichia coli. Culture independent methods included using 16S rRNA PCR amplified DNA for T-RFLP analysis and development of clone libraries for sequencing. Pronounced seasonality was found in all microbiological parameters suggesting responsiveness to surface conditions from recharge of the groundwater despite near constant groundwater temperature. Other differences may reflect the character of the drainage areas feeding different conduits and flow rates and flow reversals that affected residence time in cave conduits. In a region of groundwater flow divide, elevated numbers of a plate counts, flocculent material, and a sulfide smell were reflected in T-RFLP pattern differences. Sequence data from five selected sampling locations revealed the presence of Enterobacter and Klebsiella sequences in surface waters, but not in conduits. One conduit contained a high percentage of sequences with close homology to the archaeal species Thermococcalles archaeon. Other cave-specific sequences were found that do not match previously characterized bacteria. Overall, the data suggest both temporal and spatial differences in the microbial communities within the extensive cave system conduits feeding the spring vent, reflecting both drainage area influences and undocumented subterranean microbial diversity.     

The land fauna of Ascension Island: new data from caves and lava flows,and a reconstruction of the prehistoric ecosystem

Abstract. Terrestrial arthropods were investigated in 1990 and 1995 on Ascension, a young and extremely isolated volcanic island in the equatorial Atlantic. Three new genera (of Araneae, Oribatida and Psocoptera) were discovered and the number of apparently endemic species was increased from fourteen to about twenty-nine. Some 311 species of land animals (a few now extinct) are known to have established themselves on the island; in a few groups there may be significant numbers of unrecorded species. About ninety-five endemic and non-endemic species are considered to be native (including two marine turtles, twelve seabirds and two extinct landbirds); seventy-eight are of doubtful status; and at least 138 were probably introduced by humans. Natural colonists arrived mainly by air (drifting with the wind during migratory movements) but some evidently travelled on floating objects or attached to birds or other animals. Natural colonization was almost entirely from Africa. Before the arrival of humans, Ascension had an early successional ecosystem. The fauna in the lava and cinder deserts of the lowlands—both on the surface and in subterranean cracks and caves—was dominated by taxonomically varied scavengers and mainly arachnid predators. The scattered angiosperms here and in the foothills supported some host-specific herbivores with associated predators; they were also exploited (especially after exceptional rains) by a number of Orthoptera, Hemiptera and Lepidoptera derived from migratory African populations and perhaps reinforced at intervals by additional groups of colonists. The more extensive and largely cryptogamic vegetation on the central peak had a poor fauna probably composed mainly of micro-arthropods. Along coasts, on islets and in the extensive seabird colonies there were additional arthropod species and also a flightless rail and a night heron (both now extinct). Invertebrate stocks that colonized Ascension underwent a variety of evolutionary changes including phyletic evolution leading to endemic status, adaptation to subterranean life (Araneae, Pseudoscorpiones, Collembola and Psocoptera), character release (phorid Diptera), and probably splitting of lineages (speciation) within the island (Isopoda, Collembola and gryllid Orthoptera). The relatively high diversity of Pseudoscorpiones (five species in five genera) and their 100% apparent endemicity is notable. The indigenous fauna of Ascension provides a view of an early stage in the processes of colonization, adaptive evolution and radiation which—over much longer periods—give rise to the richer and more distinctive faunas of older oceanic islands such as Ascension's nearest neighbour, St Helena, where a few invertebrate clades have undergone repetitive speciation and some adaptive radiation.     

Comparing patterns of geographic variation in cave crickets by combining geostatistic methods and Mantel tests

Geographic variation patterns of biological characters and environmental variables are compared by using a procedure employing multivariate analyses, production of contour maps by the kriging method with enclosed validation of estimates, and Mantel tests to assess the significance of comparisons. As biological material we chose a sample of Dolichopoda cave crickets populations from Central-Southern Italy. The kriging technique provides estimates of the interpolation error for each true and estimated point. This profitable feature offers the opportunity to use, with ascertained levels of confidence, the estimated z -scores for further analysis and to compare data collected within the same area, but not exactly coincident in location or number. In such a way, we were able to use for subsequent comparisons by means of Mantel tests the maximum number of data points for all data sets, which originally differed in sampling sites. The interpretation of the contour maps and their statistical comparison suggested that allozymes and epiphallus shape data sets follow the phylogenetic pathways within the Dolichopoda populations, whereas variation in leg elongation is almost entirely under the control of an environmental gradient, synthetically described by the cave temperature.     

Genetic variability and differentiation of hypogean Cyprinid fishes from Somalia

The genetic structure of populations of two hypogean Somali cyprinid species was compared by analysing genetic variation at 30 allozyme loci. The two species, Phreatichthys andruzzii and Barbopsis devecchii , are of particular interest, representing two different steps in adaptation to cave life, as indicated by several morphological features including eye regression. Phreatichthys is completely anophthalmic, while Barbopsis shows a highly variable microphthalmia. Results showed a close relationship between Phreatichthys and Barbopsis , suggesting their origin from a common epigean ancestor. Population structure of the two species differs and levels of gene flow are much higher between the Barbopsis populations than between the Phreatichthys populations. Two possible scenarios leading to the current situation are hypothesized.     

Biology of the New Zealand genus Neolimnia (Diptera: Sciomyzidae)

Abstract

Data are presented on the life cycles of eight species of Neolimnia, an endemic New Zealand genus of snail-killing flies. Habitats, geographical distributions, biological features of adults and immature stages, including adult and larval behaviour and feeding habits, and phenology are discussed. Larvae of subgenus Pseudolimnia live in aquatic environments; those of N. (P.) repo, N. (P.) sigma, and N. (P.) ura prey on aquatic pulmonate snails, but those of N. (P.) tranquilla prey on aquatic prosobranch snails. Larvae of Neolimnia (Neolimnia) castanea, N. (N.) irrorata, N. (N.) obscura, and N. (N.) striata live in terrestrial environments, and apparently prey overtly on terrestrial snails in nature, but will also attack aquatic snails in laboratory rearings.     

喀斯特区不同退化程度植被群落植物-凋落物-土壤-微生物生态化学计量特征

为摸清喀斯特植被退化对群落各组分C、N、P生态化学计量特征及内稳态特征的影响，为喀斯特退化生态系统植被恢复与重建提供科学依据，以桂西北喀斯特地区5种退化程度植被群落为研究对象，测定了不同退化程度植被群落植物叶片、凋落物、土壤和微生物生物量的C、N、P含量，分析其化学计量比特征、相互关系及植物内稳性特征。结果表明：(1)随着退化程度加剧，叶片C、N、P含量、N∶P和凋落物N∶P、微生物量C显著下降，而叶片C∶N、C∶P则显著增加，且植物叶片N∶P<14;随退化程度加剧，凋落物N、P含量、土壤C、N、P含量、微生物量N、P呈先略有增后显著降低的趋势，且不同退化程度群落土壤N∶P和微生物量C∶N无显著差异。(2)叶片N、P含量与土壤N、P含量，叶片C∶P与土壤C∶N、C∶P、N∶P,叶片N∶P与凋落物N、N∶P,叶片C、N、P含量与微生物量C呈显著或极显著正相关关系；叶片C∶N与土壤C、N,叶片C∶P与土壤N、P,叶片N∶P与土壤P呈显著或极显著负相关关系。(3)喀斯特地区植物叶片N、P元素的内稳性指数(H)平均值分别为2.74和2.31,属于弱稳态型，叶片N∶P的H值为5.14,为稳...     

Ancient mitochondrial genomes from Chinese cave hyenas provide insights into the evolutionary history of the genus Crocuta

Cave hyenas (genus Crocuta) are extinct bone-cracking carnivores from the family Hyaenidae and are generally split into two taxa that correspond to a European/Eurasian and an (East) Asian lineage. They are close relatives of the extant African spotted hyenas, the only extant member of the genus Crocuta. Cave hyenas inhabited a wide range across Eurasia during the Pleistocene, but became extinct at the end of the Late Pleistocene. Using genetic and genomic datasets, previous studies have proposed different scenarios about the evolutionary history of Crocuta. However, causes of the extinction of cave hyenas are widely speculative and samples from China are severely understudied. In this study, we assembled near-complete mitochondrial genomes from two cave hyenas from northeastern China dating to 20 240 and 20 253 calBP, representing the youngest directly dated fossils of Crocuta in Asia. Phylogenetic analyses suggest a monophyletic clade of these two samples within a deeply diverging mitochondrial haplogroup of Crocuta. Bayesian analyses suggest that the split of this Asian cave hyena mitochondrial lineage from their European and African relatives occurred approximately 1.85 Ma (95% CI 1.62–2.09 Ma), which is broadly concordant with the earliest Eurasian Crocuta fossil dating to approximately 2 Ma. Comparisons of mean genetic distance indicate that cave hyenas harboured higher genetic diversity than extant spotted hyenas, brown hyenas and aardwolves, but this is probably at least partially due to the fact that their mitochondrial lineages do not represent a monophyletic group, although this is also true for extant spotted hyenas. Moreover, the joint female effective population size of Crocuta (both cave hyenas and extant spotted hyenas) has sustained two declines during the Late Pleistocene. Combining this mitochondrial phylogeny, previous nuclear findings and fossil records, we discuss the possible relationship of fossil Crocuta in China and the extinction of cave hyenas.     

The Petralona dentition—Hominid or cave bear?

Four teeth were recovered from the Petralona cave site in Greece. These specimens were considered to be hominid remains and have become part of the dental data base for the Pleistocene hominids of Europe. SEM analysis of the anamel structure of these remains reveals an enamel prism pattern which is not hominid. A walled hexagonal prism was obtained which is representative of the carnivores.Subsequent analysis of a fragment of enamel from the Petralona hominid cranium revealed a keyhole enamel prism, typical of modern man, while analysis of a number of cave bear teeth revealed an identical walled hexagonal prism, as was found in the four isolated teeth.The conclusion is that the four isolated teeth are those of the Pleistocene cave bear which frequently populated the cave.     

桢楠幼苗适应喀斯特岩溶裂隙生境及降雨时间格局变化的方式

喀斯特生态系统是全球陆地生态系统的重要组成部分，生态环境极为脆弱。由于碳酸盐岩长期强烈的化学溶蚀作用，其基本特征体现为地表土壤和地下岩溶裂隙及洞穴的二元结构。近年来，在全球气候变化下，我国西南地区降雨格局呈现降雨频次减少且单次降雨量增加的趋势。因此，岩溶裂隙和区域降雨时间格局改变将对喀斯特地区的植物生长产生重要影响。通过模拟不同岩溶裂隙生境(S₀:24 cm土壤；S_1/2:12 cm土壤层+12 cm裂隙层；S_3/4:6 cm土壤层+18 cm裂隙层)和不同降雨时间格局(I_2d:2 d降雨间隔；I_19d:19 d降雨间隔),探究二年生桢楠(Phoebe zhennan S. Lee)幼苗是否通过生物量分配及根系分布的调整来适应变化环境。结果显示：(1)短时间降雨格局下，相比全土生境，少量岩溶裂隙存在并不影响桢楠幼苗生物量的积累，然而随着岩溶裂隙层进一步增厚和降雨时间间隔延长，桢楠降低了总生物量，减少了茎且增大了根和叶的生物量分配。(2)桢楠幼苗的根系垂直分布随着深度增加而下降，...