Menez-Dregan 1 (Plouhinec,Finistère,France) : un site d’habitat du Paléolithique inférieur en grotte marine. Stratigraphie,structures de combustion,industries riches en galets aménagés

The Lower Palaeolithic site of Menez-Dregan I is currently the subject of an important excavation and has been part of a multidisciplinary project since 1991. It is an ancient marine cave whose roof has gradually collapsed and thus partly protected the site from erosion. In Menez-Dregan 1, the sedimentological evidence has been significantly reduced due to multiple episodes of marine erosion in the cave (low sedimentary preservation in terms of sedimentation and erosion process). However, the proximity of a section with a longer sedimentary record (Gwendrez cliff) has allowed for an attempt at correlation between the different deposits by way of a sedimentologic study applied to sandy marker beds (dunes). The resulting new data permitted a more precise chronostratigraphy of this site to be drawn up and contributed to further validation of dating. Three main stratigraphic units show distinct levels of human occupation at the site, separated by coastal deposits. The ESR dates tend to place the first human occupation in MIS 12 or at the end of MIS 13 (around 465,000 years). The ESR dating obtained at the base of layer 5 gave an age of 380,000 years. The geological analysis (sedimentology, stratigraphical correlations at short distance) tends to confirm these dates. The fauna has not preserved due to the acidic environment, leaving only the lithic industry to show how the human groups who settled at the site lived and, it is worth noting, mastered fire lighting, and or control, at a very early date (late MIS 13 or early MIS 12). The lithic industry from the upper levels (layer 5) is likely Colombanian and is composed of numerous flakes and cores alongside a great quantity of cobble tools (mostly choppers), fractured cobbles, and cobbles with isolated removals on various types of rocks, some cleavers and very rare bifaces. Additionally denticulates and notches form the main part of the light duty tools, together with scrapers. These retouched light duty tools are mainly made on flint, but quartz and glossy sandstone were also used. The last level of occupation (layer 4) probably shows the transition between Lower and Middle Palaeolithic. This may represent a regional cobble tool industry of the south armorican shoreline, however, it is still difficult to separate it totally from the classic European Acheulean from Northern France. These armorican lithic industries could indeed correspond with areas of specialised activities, as demonstrated for some Middle Palaeolithic groups with a cobble tools lithic industry. The notion of culture that could be chosen to explain this variability must be treated with caution, because it would only be based on the presence or absence of only one type of tool (the handaxe).     

Morphometric analysis of interspecific and microgeographic variation of crayfish from a Mexican cave

Two undescribed species of Procambarus crayfish (Crustacea, Decapoda) inhabit the subterranean stream running in the recently explored Cueva de Los Camarones, Chiapas, Mexico. Individuals ranging from dark, robust, large-eyed forms with an epigean mien to pale, comparatively slender, microphthalmic ones resembling related troglobites were found, but only the extremes could be distinguished visually. Evolutionary relationships among individuals were investigated morphometrically by means of multivariate analysis'on 14 body dimensions. These analyses revealed a significant discontinuity between the two species, mainly determined by the shape of the rostrum, chelae and telson. The occurrence of a few aberrant phenotypes may indicate the existence of some gene flow between the two species.
Microgeographic variation was demonstrated within the less cavernicolous species. The characters involved were the same as those that discriminate between the two species. These results are compared with allozymic data presented in a parallel paper and the role of genie introgression and environmental induction are discussed.     

Toxic hydrogen sulphide and dark caves: pronounced male life-history divergence among locally adapted Poecilia mexicana (Poeciliidae)

Chronic environmental stress is known to induce evolutionary change. Here, we assessed male life‐history trait divergence in the neotropical fish Poecilia mexicana from a system that has been described to undergo incipient ecological speciation in adjacent, but reproductively isolated toxic/nontoxic and surface/cave habitats. Examining both field‐caught and common garden–reared specimens, we investigated the extent of differentiation and plasticity of life‐history strategies employed by male P. mexicana. We found strong site‐specific life‐history divergence in traits such as fat content, standard length and gonadosomatic index. The majority of site‐specific life‐history differences were also expressed under common garden–rearing conditions. We propose that apparent conservatism of male life histories is the result of other (genetically based) changes in physiology and behaviour between populations. Together with the results from previous studies, this is strong evidence for local adaptation as a result of ecologically based divergent selection.     

Molecular phylogeny and phylogeography of the Cuban cave-fishes of the genus Lucifuga: evidence for cryptic allopatric diversity

Underground environments are increasingly recognized as reservoirs of faunal diversity. Extreme environmental conditions and limited dispersal ability of underground organisms have been acknowledged as important factors promoting divergence between species and conspecific populations. However, in many instances, there is no correlation between genetic divergence and morphological differentiation. Lucifuga Poey is a stygobiotic fish genus that lives in Cuban and Bahamian caves. In Cuba, it offers a unique opportunity to study the influence of habitat fragmentation on the genetic divergence of stygobiotic species and populations. The genus includes four species and one morphological variant that have contrasting geographical distributions. In this study, we first performed a molecular phylogenetic analysis of the Lucifuga Cuban species using mitochondrial and nuclear markers. The mitochondrial phylogeny revealed three deeply divergent clades that were supported by nuclear and morphological characters. Within two of these main clades, we identified five lineages that are candidate cryptic species and a taxonomical synonymy between Lucifuga subterranea and Lucifuga teresinarum. Secondly, phylogeographic analysis using a fragment of the cytochrome b gene was performed for Lucifuga dentata, the most widely distributed species. We found strong geographical organization of the haplotype clades at different geographic scales that can be explained by episodes of dispersal and population expansion followed by population fragmentation and restricted gene flow. At a larger temporal scale, these processes could also explain the diversification and the distribution of the different species.     

Local adaptation and pronounced genetic differentiation in an extremophile fish, Poecilia mexicana, inhabiting a Mexican cave with toxic hydrogen sulphide

We investigated genetic differentiation and migration patterns in a small livebearing fish, Poecilia mexicana, inhabiting a sulfidic Mexican limestone cave (Cueva del Azufre). We examined fish from three different cave chambers, the sulfidic surface creek draining the cave (El Azufre) and a nearby surface creek without the toxic hydrogen sulphide (Arroyo Cristal). Using microsatellite analysis of 10 unlinked loci, we found pronounced genetic differentiation among the three major habitats: Arroyo Cristal, El Azufre and the cave. Genetic differentiation was also found within the cave between different pools. An estimation of first-generation migrants suggests that (i) migration is unidirectional, out of the cave, and (ii) migration among different cave chambers occurs to some extent. We investigated if the pattern of genetic differentiation is also reflected in a morphological trait, eye size. Relatively large eyes were found in surface habitats, small eyes in the anterior cave chambers, and the smallest eyes were detected in the innermost cave chamber (XIII). This pattern shows some congruence with a previously proposed morphocline in eye size. However, our data do not support the proposed mechanism for this morphocline, namely that it would be maintained by migration from both directions into the middle cave chambers. This would have led to an increased variance in eye size in the middle cave chambers, which we did not find. Restricted gene flow between the cave and the surface can be explained by local adaptations to extreme environmental conditions, namely H2S and absence of light. Within the cave system, habitat properties are patchy, and genetic differentiation between cave chambers despite migration could indicate local adaptation at an even smaller scale.     

A new cavefish of Sinocyclocheilus (Teleostei: Cypriniformes: Cyprinidae) from the Nanpanjiang River in Guizhou,China

A new species, Sinocyclocheilus xingyiensis, is described based on specimens collected from a karst cave in Guizhou Province, China. The authors used an integrated taxonomic approach, including morphological and molecular data, to identify the new species as a member of the Sinocyclocheilu angularis group, and it can be distinguished from all other members of this group by a combination of the following features: two pairs of long barbels and long pectoral fins, 42–46 lateral-line scales, 7 (13–14) on outer (inner) side of the first gill arch and 35 (14–15 + 4 + 16 − 17) vertebrae. Phylogenetic analyses based on the cytochrome b (cyt b) gene fragment suggest that S. xingyiensis is a sister lineage to Sinocyclocheilus flexuosdorsalis. The genetic distance (Kimura 2-parameter) between the S. xingyiensis and S. angularis groups of Sinocyclocheilus species based on cyt b gene fragment ranged from 1.2% to 15.4%.     

中国重庆洞穴喀蛛属一新种记述(蜘蛛目,球体蛛科)

记述了采自中国重庆洞穴内的球体蛛科喀蛛属1新种,心形喀蛛Karstia cordata sp.nov.,模式标本保存在四川大学自然博物馆(SCUM).心形喀蛛,新种Karstia cordata sp.nov.(图1～18)新种与上扬子喀蛛K.upperyangtzica Chen,2010相似,但它们的区别在于:前者具1插入器附片,后者缺失;前者插入器突不分叉,后者多分叉;前者中突表面呈具细齿锉刀状,后者光滑;前者雌性生殖板呈心形,后者为近三角形,前者纳精囊宽且长,后者窄而短.正模♂,产自中国重庆市武隆县土地乡天生村硝洞(29.53°N,107.85°E;海拔1050 m),2010-10-17.副模:1 ♂,3♀ ♀,采集信息同正模;2 ♂♂,10♀ ♀,产自四川省华蓥市洋河镇盐井沟村垛子石洞(30.29°N,106.77°E),2010-10-16,均为林玉成和窦亮采集.词源:新种种名源自拉丁词语cordatus(心形的),意指该种雌性生殖板形状;形容词.     

喀斯特峰丛洼地不同森林表层土壤有机质的空间变异及成因

基于动态监测样地(200 m×40 m)的网格(10 m×10 m)取样,以农作区为对照,用地统计学方法研究了喀斯特峰丛洼地人工林、次生林和原生林3类典型森林生态系统表层土壤(0—15 cm)有机质的空间变异,通过主成分分析和相关分析,探讨了其生态学过程和机制。结果表明:喀斯特峰丛洼地土壤有机质很高,沿着农作区-人工林-次生林-原生林的恢复梯度,土壤有机质显著提高,变异系数逐步增大;农作区和3类森林土壤表层有机质均具有良好的空间自相关性;农作区试验半变异函数C0/(C0+C)值为26.5%,呈中等程度的空间相关性;3类森林的C0/(C0+C)值为9.0%—22.6%,呈强烈的空间相关性;农作区和人工林土壤有机质呈单峰分布,次生林呈凹型分布,原生林呈凸型分布;不同森林的主导因子不同,农作区的主导因子为主要土壤养分,人工林为地形和物种多样性,次生林为森林结构和物种多样性,原生林为地形和物种多样性,且同一因子在不同森林与土壤表层有机质的正负作用关系和相关程度也不同。因此,农作区和3类森林应根据其土壤表层有机质的空间变异及主要影响因子制定相应的固碳措施。     

A carboniferous chondrichthyan assemblage from residues within a Triassic karst system at Cromhall quarry,Gloucestershire, England

Abstract. Sixteen different Lower Carboniferous (Tournaisian Courceyan to Chadian age, Mississippian) chondrichthyan teeth types have been extracted from Triassic erosional/aeolian fills in shallow karst systems found in the limestone quarry at Cromhall, Gloucestershire, England. These Carboniferous teeth have been found within a much larger assemblage of disarticulated bones and teeth belonging to small late Triassic terrestrial reptiles, for which Cromhall quarry is famous. The Carboniferous teeth are derived fossils, released during subaerial dissolution of the surrounding limestones. Owing to low specimen numbers and uncertainty of intraspecific character, 10 types of teeth are left in open nomenclature, although it is likely they represent new taxa. They belong to Jalodus, Ctenacanthiformes, Protacrodus, Orodus, Chomatodus, Petalodontidae, Euchondrocephali?, Helodus and Psephodus. A new genus and species, Cromhallia parvunda, of indeterminate phylogenetic relationships, is also erected. The assemblage includes also an identified suite comprising Thrinacodus ferox, Bransonella cf. nebraskensis and Stethacanthus cf. altonensis. The identification of all fish teeth found in the Cromhall assemblages as derived fossils from the Carboniferous removes any ambiguity regarding the fully terrestrial nature of the late Triassic fauna preserved in the residue‐bearing karst systems.     

黔中喀斯特次生林群落结构动态

喀斯特地区群落结构动态研究,是生态重建和石漠化治理中需解决的关键问题。该文基于黔中普定县6块永久监测样地在2013年、2015年和2019年的监测资料,分析了7年间喀斯特次生林重要值、物种消长结构、物种多样性、径级结构和垂直结构的动态特征。结果表明:(1)刺楸(Kalopanax septemlobus)、朴树(Celtis sinensis)等乔木种的优势度增大,更新率较高,竹叶椒(Zanthoxylum armatum)、杭子梢(Campylotropis macrocarpa)和火棘(Pyracantha fortuneana)等先锋种的重要值减少,且死亡率较高。(2)物种多样性指数各年间无显著差异,物种丰富度和Margalef丰富度指数呈先增加后减少的趋势,Shannon-Wiener多样性指数基本稳定,均匀度指数呈先减少后增加趋势,其在2013年和2019年之间差异显著。(3)径级和树高结构呈"倒J型"和"左偏正态"分布,各年间差异不显著,乔木层大径级(DBH≥10 cm)个体数增加,但高大乔木(H≥9 m)个体数和种数减少,灌木层中火棘、杭子梢和小冻绿树(Rhamnus rosthornii)等灌木种在0 m≤H3m和0 cm≤DBH2.5 cm的个体数减少,而刺楸、朴树等乔木种个体数增加。喀斯特次生林的自然演替过程较缓慢且复杂多样,层次结构不明显,群落总体处于演替进展的中前期,群落更新良好,将进一步以乔木占优势的方向发展。