Morphology and adaptation of aquatic mosses in an Antarctic lake

Abstract

Two species of moss growing in Moss Lake on Signy Island, South Orkney Islands, had unusual morphologies with large leaves and long internodes. Both Calliergon sarmentosum and Drepanocladus cf. aduncus differed from their terrestrial counterparts and from each other in the character of their leaves. The two genera differed in the ability of the terrestrial forms to develop a large-leaved growth form. Calliergon, which was represented by the same species in both environments, changed to the aquatic morphology when separated shoots were grown either submerged or under damp conditions. Ught intensity was not an important factor influencing change in morphology. In contrast, terrestrial Drepanocladus uncinatus, the closest taxonomic counterpart of D. cf. aduncus on Signy Island, did not show any adaptation under similar conditions. The aquatic forms also showed a corresponding degree of plasticity in their natural habitat. Calliergon varied from robust shoots to microphyllous or even leafless stems whereas Drepanocladus cf. aduncus only grew in the robust form. These differences were related to the success of the two species at different depths and it is suggested that the very low compensation points of the two mosses (reported in a separate study) resulted from the morphology of the plants.     

Locomotion pattern and trunk musculoskeletal architecture among Urodela

We comparatively examined the trunk musculature and prezygapophyseal angle of mid‐trunk vertebra in eight urodele species with different locomotive modes (aquatic Siren intermedia, Amphiuma tridactylum, Necturus maculosus and Andrias japonicus; semi‐aquatic Cynops pyrrhogaster, Cynops ensicauda; and terrestrial Hynobius nigrescens, Hynobius lichenatus and Ambystoma tigrinum). We found that the more terrestrial species were characterized by larger dorsal and abdominal muscle weight ratios compared with those of the more aquatic species, whereas muscle ratios of the lateral hypaxial musculature were larger in the more aquatic species. The lateral hypaxial muscles were thicker in the more aquatic species, whereas the M. rectus abdominis was more differentiated in the more terrestrial species. Our results suggest that larger lateral hypaxial muscles function for lateral bending during underwater locomotion in aquatic species. Larger dorsalis and abdominal muscles facilitate resistance against sagittal extension of the trunk, stabilization and support of the ventral contour line against gravity in terrestrial species. The more aquatic species possessed a more horizontal prezygapophyseal angle for more flexible lateral locomotion. In contrast, the more terrestrial species have an increasingly vertical prezygapophyseal angle to provide stronger column support against gravity. Thus, we conclude trunk structure in urodeles differs clearly according to their locomotive modes.     

Revision of the fossil vole assemblage (Mammalia,Rodentia, Arvicolidae) from Pleistocene deposits at Kisláng,Hungary

Abstract: The species‐rich fossil vertebrate assemblage from Pleistocene sedimentary deposits at Kisláng, Hungary, was originally described as containing eight species of arvicolids, six of which were considered new. Re‐examination of the material in the collection of the Hungarian Geological Institute, consisting of most of the previously described material, including the six name‐bearing types and also further undescribed specimens, indicates that the taxa Kislangia rex, Mimomys cf. hassiacus, Mimomys coelodus, Mimomys pusillus, Mimomys tornensis, Pitymimomys sp., Borsodia newtoni, Lagurodon arankae and Allophaiomys deucalion are present. Most of these species are compatible with Early Pleistocene age close to the boundary between the Villányian and Biharian regional stages (MQR10, MQ1, c. 1.6–2.0 Ma). However, the specimen of Mimomys cf. hassiacus is of approximately mid‐Pliocene age (MN15 c. 3.6–4.0 Ma), and one of the Pitymimomys specimens is referable to P. stenokorys, described from the earliest Pleistocene (MNR2–MNR3, MN17 c. 2.3–2.4 Ma). The assemblage is therefore interpreted as derived from at least three different geological periods and because of reworking of material is considered unusable to characterize any particular stratigraphic level. These conclusions are placed in the context of historical and current biostratigraphies.     

Shorebirds as important vectors for plant dispersal in Europe

Shorebirds (Charadriiformes) undergo rapid migrations with potential for long‐distance dispersal (LDD) of plants. We studied the frequency of endozoochory by shorebirds in different parts of Europe covering a broad latitudinal range and different seasons. We assessed whether plants dispersed conformed to morphological dispersal syndromes. A total of 409 excreta samples (271 faeces and 138 pellets) were collected from redshank Tringa totanus, black‐winged stilt Himantopus himantopus, pied avocet Recurvirostra avosetta, northern lapwing Vanellus vanellus, Eurasian curlew Numenius arquata and black‐tailed godwit Limosa limosa in south‐west Spain, north‐west England, southern Ireland and Iceland in 2005 and 2016, and intact seeds were extracted and identified. Godwits were sampled just before or after migratory movements between England and Iceland. The germinability of seeds was tested. Intact diaspores were recovered from all bird species and study areas, and were present in 13% of samples overall. Thirteen plant families were represented, including Charophyceae and 26 angiosperm taxa. Only four species had an ‘endozoochory syndrome’. Four alien species were recorded. Ellenberg values classified three species as aquatic and 20 as terrestrial. Overall, 89% of seeds were from terrestrial plants, and 11% from aquatic plants. Average seed length was higher in redshank pellets than in their faeces. Six species were germinated, none of which had an endozoochory syndrome. Seeds were recorded during spring and autumn migration. Plant species recorded have broad latitudinal ranges consistent with LDD via shorebirds. Crucially, morphological syndromes do not adequately predict LDD potential, and more empirical work is required to identify which plants are dispersed by shorebirds. Incorporating endozoochory by shorebirds and other migratory waterbirds into plant distribution models would allow us to better understand the natural processes that facilitated colonization of oceanic islands, or to improve predictions of how plants will respond to climate change, or how alien species spread.     

The ontogeny of the olfactory system in ceratophryid frogs (Anura,Ceratophryidae)

The aquatic‐to‐terrestrial shift in the life cycle of most anurans suggests that the differences between the larval and adult morphology of the nose are required for sensory function in two media with different physical characteristics. However, a better controlled test of specialization to medium is to compare adult stages of terrestrial frogs with those that remain fully aquatic as adults. The Ceratophryidae is a monophyletic group of neotropical frogs whose diversification from a common terrestrial ancestor gave rise to both terrestrial (Ceratophrys, Chacophrys) and aquatic (Lepidobatrachus) adults. So, ceratophryids represent an excellent model to analyze the morphology and possible changes related to a secondary aquatic life. We describe the histomorphology of the nose during the ontogeny of the Ceratophryidae, paying particular attention to the condition in adult stages of the recessus olfactorius (a small area of olfactory epithelium that appears to be used for aquatic olfaction) and the eminentia olfactoria (a raised ridge on the floor of the principal cavity correlated with terrestrial olfaction). The species examined (Ceratophrys cranwelli, Chacophrys pierottii, Lepidobatrachus laevis, and L. llanensis) share a common larval olfactory organ composed by the principal cavity, the vomeronasal organ and the lateral appendix. At postmetamorphic stages, ceratophryids present a common morphology of the nose with the principal, middle, and inferior cavities with characteristics similar to other neobatrachians at the end of metamorphosis. However, in advanced adult stages, Lepidobatrachus laevis presents a recessus olfactorius with a heightened (peramorphic) development and a rudimentary (paedomorphic) eminentia olfactoria. Thus, the adult nose in Lepidobatrachus laevis arises from a common developmental ‘terrestrial’ pathway up to postmetamorphic stages, when its ontogeny leads to a distinctive morphology related to the evolutionarily derived, secondarily aquatic life of adults of this lineage.     

First record for the slug parasitic nematode,Phasmarhabditis hermaphrodita (Schneider) in Egypt

The rhabditid nematode, Phasmarhabditis hermaphrodita is a lethal parasite of certain terrestrial gastropods and has been shown as a biocontrol agent under laboratory and field conditions. In Egypt, P. hermaphrodita was isolated for the first time from different species of terrestrial gastropods found associated with various crops at Aga and Mansoura districts of Dakhalia Governorate during the year 2000/2001. Females and dauer larvae (IJs) were described and illustrated based on the light microscope. Males are not found as this species seemed to be protandrous. PCR analysis confirmed nematode identification. The Egyptian isolate of P. hermaphrodita was found to be shorter and lower in width than the British isolate. V%, a, b and c parameters showed detectable variations between two isolates with values of 54%, 17.7, 4.28, 13.7 in the Egyptian isolate, and 51%, 19.5, 7.2 and 15.8 for the British isolate, respectively.     

Spatial distribution and habitat of the Anavilhanas Archipelago bird community in the Brazilian Amazon

This study is the first to present a quantitative survey of bird species occurring in the archipelago of Anavilhanas, located in the Rio Negro in the Brazilian Amazon and is part of the Anavilhanas Ecological Station. We asked whether bird community composition is similar among the islands, and between islands and areas dominated by the surrounding upland terra firme forest on the left (east) margin of the Rio Negro. The surveys were conducted in November and December of 1988, using two complementary methods with mist nets and boat transects. A total of 232 bird species was found for Anavilhanas including a survey done in 1998. The families Tyrannidae and Thamnophilidae showed the highest number of species (16.4% and 9.0% of the total respectively). Some species not well known or having limited distributions are relatively frequently encountered in the archipelago, such as Spizastur melanoleucus, Mitu tomentosa, Phaethornis rupurumii, Xiphorhynchus kienerii, Thamnophilus nigrocinereus, Myrmotherula klagesi, Myrmoborus lugubris, Pipra filicauda, and Cephalopterus ornatus. Hybrid Multidimensional Scaling (HMDS) ordination analysis indicated that the bird community composition is similar among islands. However, the bird community composition on the islands was significantly different from that in sites of terra firme forest at Rio Negro margins. Anavilhanas is a unique ecological system in the Amazon and has it own avifauna.     

Potential alteration of cross‐ecosystem resource subsidies by an invasive aquatic macroinvertebrate: implications for the terrestrial food web

相似文献   

不同生境下空心莲子草响应模拟昆虫采食的生长和化学防御策略

外来植物往往可以入侵多种生境并受到多种昆虫的采食,而不同生境条件将可能会影响这些入侵植物对昆虫采食的防御策略。以入侵我国的克隆植物——空心莲子草为研究对象,分别选择生长在水生生境、水陆两栖生境和陆生生境中的无性个体(分株),通过50%去叶处理模拟昆虫采食,分析不同生境下空心莲子草对模拟昆虫采食处理的生长及化学防御响应的差异。模拟昆虫采食处理显著抑制了陆生生境、水陆两栖生境以及水生生境下空心莲子草的根、茎、叶和总生物量,但对3种生境下空心莲子草的生物量分配(根冠比、根生物量分配、茎生物量分配和叶生物量分配)均无显著影响。陆生生境下空心莲子草根、茎和总生物量显著高于水陆两栖生境和水生生境,根冠比显著低于水陆两栖生境和水生生境。模拟昆虫采食处理显著降低了空心莲子草的木质素含量,而对单宁和总酚含量影响不显著。生境对木质素含量无显著影响,但陆生生境下空心莲子草单宁含量显著高于水陆两栖生境和水生生境,且总酚含量显著高于水陆两栖生境,表明陆生生境中空心莲子草具有更强的防御能力。空心莲子草木质素含量与总生物量无显著相关性,但在模拟采食情况下,其总酚含量与总生物量呈显著负相关,而无论模拟昆虫采食处理存在与否,空心莲子草单宁含量与总生物量均呈显著正相关。因此,空心莲子草存在昆虫介导的生长和化学防御之间的权衡,在昆虫采食的情况下可通过减少生长来增加对化学防御物质的投入,但生境对空心莲子草这种生长-防御权衡的影响十分有限。     

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.     

Do birds of a feather disperse plants together?

1. Dispersal of propagules by waterbirds is thought to be important for wetland plants because of the abundance of birds and their frequent movements among aquatic habitats. Differences in bird characteristics (size, movement, feeding ecology) were expected to lead to different outcomes for plant dispersal. 2. We investigated heterogeneity in plant dispersal by ducks (Anas superciliosa, Anas gracilis, Anas castanea). We calculated the probability of transport of viable seeds by germinating propagules retrieved from feathers and feet (epizoochory) and the contents of the oesophagus, gizzard and lower gut (endozoochory). 3. The abundance and richness of seeds carried internally and externally did not differ among sympatric bird species. We used estimates from the literature of movements of Anas species to approximate dispersal kernels for the transport of plant propagules. 4. Heterogeneity in the abundance and movement ecology of disperser species will result in differing patterns and degrees of connectivity for wetland plant metacommunities. Sedentary waterfowl are likely to have an important role in replenishing propagules and connecting aquatic metacommunities over small distances. Nomadic waterfowl may facilitate long‐distance dispersal. We discuss the implications of differences between duck species in movement patterns for connectivity of aquatic plant metacommunities across landscapes.     

Incidence of Wolbachia in aquatic insects

Wolbachia is a genus of intracellular bacteria typically found within the reproductive systems of insects that manipulates those systems of their hosts. While current estimates of Wolbachia incidence suggest that it infects approximately half of all arthropod species, these estimates are based almost entirely on terrestrial insects. No systematic survey of Wolbachia in aquatic insects has been performed. To estimate Wolbachia incidence among aquatic insect species, we combined field‐collected samples from the Missouri River (251 samples from 58 species) with a global database from previously published surveys. The final database contained 5,598 samples of 2,687 total species (228 aquatic and 2,459 terrestrial). We estimate that 52% (95% CrIs: 44%–60%) of aquatic insect species carry Wolbachia, compared to 60% (58%–63%) of terrestrial insects. Among aquatic insects, infected orders included Odonata, Coleoptera, Trichoptera, Ephemeroptera, Diptera, Hemiptera, and Plecoptera. Incidence was highest within aquatic Diptera and Hemiptera (69%), Odonata (50%), and Coleoptera (53%), and was lowest within Ephemeroptera (13%). These results indicate that Wolbachia is common among aquatic insects, but incidence varies widely across orders and is especially uncertain in those orders with low sample sizes such as Ephemeroptera, Plecoptera, and Trichoptera.     

Feeding ecology of a vertebrate assemblage inhabiting a stream of NW Spain (Riobo; Ulla basin)

The food resource use of a stream in NW Spain by fish (Salmo trutta L. and Anguilla anguilla L.), birds (Cinclus cinclus L. and Motacilla cinerea L.) and mammals (Galemys pyrenaicus G. and Neomys anomalus C.) was studied. Data on seasonal diets and stream benthos prey were used to determine prey selection patterns.Caddisfly larvae are the main resource for Cinclus and Galemys, but these predators also consumed other benthic prey. Salmo fed on a wide range of benthic invertebrates, emergent pupae and terrestrial prey, whereas Anguilla consumed primarily benthic invertebrates, especially Lumbricids. Neomys fed mainly on terrestrial prey (Gasteropods and Lumbricids), but also consumed aquatic prey. Motacilla captured aquatic insects both in larval and aerial stages, as well as terrestrial prey.Both prey availability and selection led to seasonal differences in the use of food resources. All species showed a marked prey selection of aquatic taxa. Prey size plays an important role in this selection, most species consuming the largest of available prey sizes. In spite of the fact that all species feed upon freshwater invertebrates, substantial resource partitioning was observed in all seasons. This partitioning may be attributable to morpholological and physiological differences. Nevertheless, Anguilla and Galemys, two quite different animals, did feed on the same prey much of the time.     

Genetic Differentiation Among Annual Fishes of the Genus Cynolebias (Cyprinodontiformes, Rivuluidae) in a Biosphere Reserve Site from Uruguay

The annual killifishes of the genus Cynolebias include one well supported clade composed of three taxa: Cynolebias adloffi, from Porto Alegre (southern Brazil), C. cf. adloffi and Cynolebias viarius, parapatrically distributed in southeastern Uruguay. Cynolebias cf. adloffi has always been considered an intergradation complex of populations between C. adloffi and C. viarius showing high levels of morphological variability and its systematic affinities have been historically discussed. This study clarified the patterns of genetic differentiation of C. cf. adloffi by means of RAPD markers to define its taxonomic status as a possible separated taxon. Multidimensional scaling analysis reveals that C. cf. adloffi is composed of two highly structured genetic groups (northern and southern) with discrete geographical distributions. The estimate of gene diversity for RAPD markers could suggest a scenario in which the rainy season flood pool populations across large distances could make intrapopulation variation high but interpopulation variation low. Phylogenetic analyses (UPGMA and parsimony) show different and unstable patterns of relationships among the taxa analyzed. In the UPGMA tree, C. viarius and C. cf. adloffi appear as sister taxa, while parsimony analysis does not support a unique hypothesis of relationship. Our analyses are in agreement with the hypothesis that C. cf. adloffi may well be a case of ancient hybrid ancestry followed by its divergence associated with Pleistocene and post-Pleistocene environmental changes in this region.     

Characterisation (δ13C and δ15N isotopes) of the food webs in a New Zealand stream in the Waitakere Ranges,with emphasis on the trophic level of the endemic frog Leiopelma hochstetteri

Abstract

Leiopelma hochstetteri, the most widespread of New Zealand's native frogs, is recognised as threatened, and is fully protected by legislation. As a first step to characterise the diet and trophic level of L. hochstetteri within streams in the Waitakere Ranges, Auckland, stable carbon and nitrogen isotope analyses were undertaken on a variety of sympatric terrestrial and aquatic plant and animal species, including adult frogs. These results show that: (1) aquatic and terrestrial food webs are linked by terrestrial inputs into the stream; (2) invertebrate and vertebrate predators separate well into distinct trophic groups, and (3) L. hochstetteri occupies an intermediate trophic position among predators, with a diet, at least as an adult, comprising terrestrial invertebrates. Shortfin eels and banded kokopu are identified as potential predators of L. hochstetteri, but data for rats are inconclusive. These results have important implications for the conservation of New Zealand native frog species and riparian stream habitat.     

Aquatic adaptations in a Neotropical coral snake: A study of morphological convergence

Micrurus surinamensis is an aquatic member of the genus Micrurus. This species is known for its highly specialized venom and distinctive diet, mostly made of aquatic vertebrates. Here, we explore both external (head and body) and skull shape morphologies in M. surinamensis, comparing it with two terrestrial species of the genus (M. lemniscatus and M. spixii) and to aquatic and terrestrial species of distantly related groups. We use both traditional and geometric morphometrics to determine whether the presence of similar traits in head shape morphology is rather the result of adaptive convergences between M. surinamensis and other aquatic species, or whether it is the product of phylogenetic conservatism within the genus. Results from both traditional and geometric morphometrics show that M. surinamensis can be considered convergent with aquatic species, mainly in the skull shape. Micrurus surinamensis differs from the two terrestrial species of Micrurus by having a wider head, smaller distance between nostrils, and a long tail. Geometric morphometric analysis shows that despite having an extremely conserved skull and mandible shape, M. surinamensis shows a longer supratemporal and quadrate bones than in terrestrial Micrurus, indicating a larger gape for this species. A more kinetic skull combined with a larger gape would allow M. surinamensis to feed on fish, which represent larger and wider prey that contrast with the elongate prey, which compose the main diet of species in the genus Micrurus. Our results illustrate the importance of both phylogenetic conservatism and adaptation in shaping species morphology.     

Patterns of bird species richness and composition on islands off Arnhem Land,Northern Territory,Australia

The bird faunas of the adjacent Wessel and English Company island chains were sampled at two scales (0.25 ha quadrats and entire islands). Ninety‐six species were recorded from 226 quadrats, with the most frequently recorded species being mistletoebird Dicaeum hirundinaceum, brown honeyeater Lichmera indistincta, silver‐crowned friarbird Philemon argenticeps, bar‐shouldered dove Geopelia humeralis, northern fantail Rhipidura rufiventris and yellow white‐eye Zosterops lutea. At the quadrat scale, vegetation type was a major determinant of the abundance of individual species (and hence species composition), species richness and total bird abundance. Bird species composition and richness at the quadrat scale was also significantly affected by island isolation (particularly the amount of land within 20 km of the island perimeter). Island size had no effect on quadrat‐scale richness or total abundance. However, the abundance of 10 of the 38 most frequently recorded individual species was significantly related to island size, in most cases even when the comparison was restricted to similar habitats. The most striking cases were rufous fantail Rhipidura rufifrons, mangrove golden whistler Pachycephala melanura, brown honeyeater and yellow white‐eye, which were all significantly more abundant on smaller islands. One hundred and seventy‐one species were recorded from the 62 islands sampled. There was a very tight relationship between island size and the number of terrestrial species (73% of deviance explained) and of all species (84% of deviance explained). This relationship was improved (marginally) when isolation was included in the model. Ordination of islands by their terrestrial bird species composition was related to island size and isolation, and suggested an erratic species composition on small islands.     

Landscape context influences the abundance of amphibians and the strength of their food web interactions in small ponds

Many species, including most amphibians, undergo an ontogenetic niche shift (ONS) from an aquatic larval stage to a terrestrial adult stage. We use the ratio of aquatic to terrestrial habitat in a landscape as a tool to understand the influence of landscape context on the population growth of ONS species. The aquatic to terrestrial ratio (ATR) of habitats can be viewed as an analog to the influence of resource ratios on the population growth of consumers and depends on the degree to which each habitat type limits the growth of a given population. Population growth rates of shorter‐lived species tend to be more limited by demographic rates in early (aquatic) life stages. As a result, increasing the ATR should lead to a higher total population size in the landscape (and higher densities in the terrestrial habitat), but have little influence on the density of individuals in any given aquatic habitat. Alternatively, population growth rates of longer‐lived species tend to be more limited by demographic rates in later (terrestrial) life stages and increasing the ATR should have little influence on the total population size in the landscape, but decrease the density of individuals in any given aquatic habitat. We show that among‐landscape variation in the breeding‐pond densities of three widespread amphibians with contrasting life histories is consistent with this framework. Within‐pond densities of Pseudacris crucifer, a species with short‐lived adults, were not influenced by ATR, whereas within‐pond densities of Hyla versicolor, a longer‐lived member of the same family (Hylidae), declined as ATR increased. Ambystoma maculatum, a long‐lived salamander, also had lower densities in ponds with higher ATR. Because A. maculatum larvae are important predators in ponds, we use structural equation modeling to show that landscape context (ATR) can moderate community structure via direct (amphibian abundances) and indirect (prey species richness) effects.     

Impact of three aquatic invasive species on native plants and macroinvertebrates in temperate ponds

Biological plant invasions pose a serious threat to native biodiversity and have received much attention, especially in terrestrial habitats. In freshwater ecosystems impacts of invasive plant species are less studied. We hypothesized an impact on organisms from the water column and from the sediment. We then assessed the impact of three aquatic invasive species on the plants and macroinvertebrates: Hydrocotyle ranunculoides, Ludwigia grandiflora and Myriophyllum aquaticum. Our research on 32 ponds in Belgium indicated that the reduction in the native plant species richness was a common pattern to invasion. However, the magnitude of impacts were species specific. A strong negative relationship to invasive species cover was found, with submerged vegetation the most vulnerable to the invasion. Invertebrate richness, diversity and abundance were measured in sediments of invaded and uninvaded ponds along a gradient of H. ranunculoides, L. grandiflora, and M. aquaticum species cover. We found a strong negative relationship between invasive species cover and invertebrate abundance, probably due to unsuitable conditions of the detritus for invertebrate colonization. Taxonomic compositions of aquatic invertebrate assemblages in invaded ponds differed from uninvaded ponds. Sensitive benthos, such as mayflies were completely absent in invaded ponds. The introduction of H. ranunculoides, L. grandiflora, and M. aquaticum in Belgian ponds has caused significant ecological alterations in the aquatic vegetation and the detritus community of ponds.     

On the systematic position of the large-sized deer from Apollonia,Early Pleistocene,Greece

The revision of the large-sized deer association from the early Pleistocene site Apollonia (Early Pleistocene; Greece), revealed the presence of two species,Praemegaceros pliotarandoides (De Alessandri, 1903) and a giant representative of the genusArvernoceros. P. pliotarandoides (=Psekupsoceros orientalis Radulesco & Samson, 1967) is characterized by advanced dental morphology, lack of the middle antler tine, and dichotomously branched distal part of the antlers and is regarded as the direct forerunner of middle PleistoceneP. verticornis. The species attribution of the ApollonianArvernoceros is not clear enough because of the incomplete data, and for this reason we keep this form under the nameArvernoceros cf.verestchagini. The presence ofArvernoceros in Apollonia certainly extends its chronological occurrence to early Pleistocene and a new generic definition is proposed. Several taxonomic and systematic questions on early Pleistocene large-sized deer of Europe are also discussed.