Taxonomic and functional homogenization of an endemic desert fish fauna

Aim The highly endemic fishes of the arid Southwest USA have been heavily impacted by human activities resulting in one of the most threatened fish faunas in the world. The aim of this study was to examine the patterns and drivers of taxonomic and functional beta diversity of freshwater fish in the Lower Colorado River Basin across the 20th century. Location Lower Colorado River Basin (LCRB). Methods The taxonomic and functional similarities of watersheds were quantified to identify patterns of biotic homogenization or differentiation over the period 1900–1999. Path analysis was used to identify the relative influence of dam density, urban land use, precipitation regimes and non‐native species richness on observed changes in fish faunal composition. Results The fish fauna of the LCRB has become increasingly homogenized, both taxonomically (1.1% based on β_sim index) and functionally (6.2% based on Bray–Curtis index), over the 20th century. The rate of homogenization varied substantially; range declines of native species initially caused taxonomic differentiation (?7.9% in the 1960s), followed by marginal homogenization (observed in the 1990s) in response to an influx of non‐native species introductions. By contrast, functional homogenization of the basin was evident considerably earlier (in the 1950s) because of the widespread introduction of non‐native species sharing similar suites of biological traits. Path analysis revealed that both taxonomic and functional homogenization were positively related to the direct and indirect (facilitation by dams and urbanization) effects of non‐native species richness. Main conclusions Our study simultaneously examines rates of change in multiple dimensions of the homogenization process. For the endemic fish fauna of the LCRB, we found that the processes of taxonomic and functional homogenization are highly dynamic over time, varying both in terms of the magnitude and rate of change over the 20th century.     

The Ethiopian subregion fish fauna: an original patchwork with various origins

In this article, I analysed the biogeographical distribution and the historical origin of freshwater fish of the Ethiopian Rift Valley (ERV) region which is not a homogeneous area. The Ethiopian region, including Eritrea and part of Somalia, includes 13 basins as geographical units. A comparison was carried out with four Near East geographical units. A correspondence analysis was applied to presence–absence data for the 17 basins × 170 species’ matrix. Then, a faunistic distance (Euclidian distance) between basins was computed from the coordinates of factors retained in this new analysis. From this faunistic distance, a hierarchical cluster analysis was performed and a dendrogram produced by a UGPMA classification. The old Abyssinian ichthyo-province (sensu Roberts, Zool J Linn Soc 57:249–319, 1975) was not homogeneous in species composition. I distinguished four main groups based on the present species composition which seemed to be mainly influenced by historical events. The species composition of the ERV basins was not randomly distributed and can be classified into four main geographical units. The importance of the historical events was demonstrated and two origins can be considered. The westernmost basins are under Nilo-Sudan influence whereas the easternmost ones seem to have been colonised from the Near East. In this Eastern part it can be distinguished three different groups: the main ERV province and two derived sub-regions, Lake Tana with a Labeobarbus intermedius related species flock and the Coastal Red Sea, characterised by a very impoverished freshwater fish fauna.     

The influence of habitat homogenization on the trophic structure of fish fauna in tropical streams

Habitat homogenization is one of the most important drivers of change in riverine fauna. Therefore, the aim of this study was to determine whether habitat homogenization influences the trophic structure of fish assemblages in tropical streams. We sampled 78 streams located in pasture and crop lands to examine habitat variables and fish. Principal coordinates analysis, canonical analysis of principal coordinates, and a distance-based test for homogeneity of multivariate dispersions revealed two groups of streams, designated homogeneous and heterogeneous, based on the habitat variables. We determined trophic guilds according to the frequency and biovolume of food items. Seven guilds were identified: aquatic insectivores, terrestrial insectivores, detritivores, herbivores, omnivores, algivores, and detritivores–algivores. Homogeneous streams showed higher abundance and biomass of aquatic insectivores, detritivores, and algivores. Heterogeneous streams showed greater diversity of trophic guilds and higher abundance and biomass of terrestrial insectivores and herbivores than homogeneous streams. Our results demonstrate that trophic structure is influenced by habitat condition. Additionally, the riparian canopy and nearshore vegetation have a modulating role in the trophic structure of stream fishes due to their influence on resource supply and promotion of the physical heterogeneity of the channel.     

The structure and spatial organization of the butterfly fauna (Lepidoptera,Rhopalocera) of the Ural Mountains

The butterfly fauna of the Ural Mountains contains 233 species: Papilionidae (6 species), Pieridae (23), Lycaenidae (64), Nymphalidae (60), Satyridae (57), and Hesperiidae (23). The number of butterfly species in seven regional and 29 local faunas generally increases gradually from north to south. The mean number of species in the local butterfly faunas is 127 in the southern Urals and slightly over 50 in the Polar Urals. The arealogical structure of the fauna is determined by the distribution of species recorded in 24 meridional and 19 latitudinal groups which together result in 80 distribution patterns. Based on comparison of the local butterfly faunas of the Urals, two large, historically formed faunistic complexes are distinguished: southern and northern. Either complex contains two faunistic complexes of the second order, hypoarctic and boreal in the former, and southern boreal and subboreal in the latter. The faunas of the Kazakhstan part of the Urals form a separate subboreal semi-arid complex, whereas the extreme boreal fauna of Pay-Khoy forms an independent arctic complex.     

The effects of recreated instream and ecotone structures on the fish fauna of an epipotamal river

Investigations of fifteen sections of seven Austrian epipotamal (barbel region) streams between 1981 and 1984 demonstrate the impact of instream river bed structures on fish communities. Reduced spatial heterogeneity due to river straightening resulted in decreasing species number, diversity, stock density and biomass. Reincreased variability of the river bed in the frame of a subsequent restructuring project improved all community-specific values significantly within a 3-year investigation period (1988–1990). Besides the regained habitat variability in form of riffle pool sequences and other instream structures, the newly created riparian zones obviously provided important niches, e.g. as refuge areas during flooding and as nursery grounds for fish fry. The positive effects of the recreated land/water ecotone are discussed with respect to river restoration projects.     

The influence of fish predation on the abundance cycles of an algal turf invertebrate fauna

Summary A fauna of small invertebrates in a perennial algal turf habitat showed marked seasonal fluctuations in abundance. These were characterised by a summer (December) peak in the abundance of gammarid amphipods and an autumn (April) peak in polychaete densities. Invertebrate abundance was lowest during the period February–March which coincided with an influx of very high densities of juveniles (0⁺ year class) of the sparid fish Chrysophrys auratus. Both juvenile C. auratus and also the mullid Upeneichthys porosus achieved their highest densities over coralline turf areas and fed on the associated invertebrates. Gammarid amphipods constituted the main food items of each species. All these observations suggested a key role of fish predators in determining the observed seasonal patterns of invertebrate abundance.This hypothesis was investigated by the use of replicated fish exclusion shields and cages which excluded both species from the algal turf and also permitted an assessment of Upeneichthys porosus feeding in the absence of Chrysophrys auratus. The experiment ran from November until June and covered the period of invertebrate and fish abundance changes. Little evidence of a fish predation effect on either the densities of or the timing of abundance peaks of the invertebrate fauna was detected. Sediment analysis of the cage and control experimental sites revealed no evidence of a cage effect on the microhabitat. It is suggested that seasonal changes in the abundance of invertebrates occurs independently of the high densities of predatory fish recorded in this habitat.     

The Tortonian fish fauna of Gavdos Island (Greece)

Although the occurrence of fossil fishes is known since more than one century in the Neogene of Gavdos Island (Greece), its composition remained hitherto unknown. The present study demonstrates that, in the Tortonian of Gavdos, the most abundant species is Bregmaceros albyi (Sauvage), which constitutes two thirds of the collected material. This fish fauna is indicative of an environment of moderate depth, probably corresponding to the external edge of the neritic zone, or possibly to the upper part of the continental slope. To cite this article: J. Gaudant et al., C. R. Palevol 4 (2005).     

The social organization of free-ranging fish shoals

The phenotypic composition of social groups can affect the foraging efficiency and predation risk of their individual members. In shoaling fishes, active choice of shoal companions on the basis of phenotypic characters such as body length has been reported. In this study, we investigated the phenotypic composition of free-ranging, multi-species fish shoals in a temperate freshwater lake. We collected 21 entire shoals, each consisting of up to four species and comprising 3622 fish in total. Shoals were strongly assorted by species, body length, parasite prevalence and parasite load. Using a mark-recapture procedure involving 785 banded killifish ( Fundulus diaphanus ), we found no evidence for shoal fidelity or site fidelity, as individuals from different shoals mixed extensively after just 24 h and ranged all over the study site irrespective of initial capture locations. Killifish showed strong changes in shoal-size choice over 24 h, and no evidence was found that shoals might break up into sub-units of individuals that are more phenotypically assorted than their original shoals. The mechanisms by which assortative groups may arise and the consequences of low group fidelity for the evolution of cooperative behaviour are discussed.     

The dominant fish fauna in the North Sea and its determination

The 224 species of fish reported from the North Sea are regarded as being composed of elements of three faunas—Boreal, Lusitanian and Atlantic, and they can be grouped accordingly on both a number of species and a biomass basis. The estimation of biomass of more than 10 important species is based on stock estimates obtained from population data. For 65 non-standard species the estimate is based on a comparison of catch rates for 'standard'and non-standard species from groundfish survey data. This involves assumption about the relative catchability of different sets of species. For the other species the biomass are computed in different ways. An analysis of the dominant fish fauna in the North Sea is attempted. The fish fauna in the area is analysed in two ways: by the conventional total number of species from each zoogeographic area, and by the biomass of the representatives of each fauna. It is concluded that for establishing the dominant faunal element of fish, biomass is a better index than is the number of species. The dominant faunal element of fish in the North Sea is Boreal.     

The southwestern Atlantic reef fish fauna: composition and zoogeographic patterns

The Brazilian coast, the Caribbean and the tropical South Atlantic oceanic islands reef ichthyofauna separated into two major clusters: (1) the western Atlantic continental margin and Bermuda, further divided into (1a) the western North Atlantic, and (1b) the Brazilian coast; and (2) the South Atlantic oceanic islands, also divided in (2a) the Brazilian offshore islands, and (2b) Ascension and St Helena. Species geographic ranges suggest the recognition of only two western Atlantic zoogeographic provinces for tropical marine shore fishes. A Brazilian Province, including the offshore localities of Atol das Rocas, Fernando de Noronha, Trindade and St Paul's Rocks, and an expanded West Indian Province that includes Bermuda. Ascension and St Helena should be regarded as a separated Central Atlantic Province.     

台湾海峡鱼类组成及其生态区系

本文依据台湾海峡鱼类物种的相关历史调查资料和文献, 分析了台湾海峡鱼类物种组成及其生态类型和区系特征, 探讨全球变化背景下台湾海峡鱼类物种组成变化。结果显示, 台湾海峡共有鱼类1,697种, 分隶40目206科740属, 其中, 目级分类阶元种类数最多的为鲈形目, 科级分类阶元种类数最多的为鰕虎科; 从适温性上看, 暖水性鱼类最多, 有1,560种, 其次为暖温性鱼类(128种)和冷温性鱼类(9种); 栖息地生态类型则以大陆架砂泥质底层鱼类和岩礁性鱼类种类数最多, 各有596种, 其后依次是大陆架近底层鱼类(249种)、大陆架中上层鱼类(158种)和大洋性鱼类(98种), 洄游性鱼类181种, 经济性鱼类735种; 海区间鱼类种类数对比显示, 台湾海峡鱼类与南海鱼类共有种最多, 共有种比例高达91.9%, 其次为东海(69.3%)和黄海(19.4%), 多为印度—西太平洋海区分布种, 仅288种广泛分布于中国各海区。由此, 台湾海峡鱼类区系特征兼有热带和亚热带海区鱼类区系特点, 属于印度—西太平洋暖水区系中—日亚区和印度—马来亚区的过渡海区, 其分界区域在台湾浅滩东部外缘至澎湖列岛偏北海域。     

Hawaiian biogeography and the islands' freshwater fish fauna

Aim This paper describes known patterns in the distributions and relationships of Hawaiian freshwater fishes, and compares these patterns with those exhibited by Hawaii's terrestrial biota. Location The study is based in Hawaii, and seeks patterns across the tropical and subtropical Indo‐west Pacific. Methods The study is based primarily on literature analysis. Results The Hawaiian freshwater fish fauna comprises five species of goby in five different genera (Gobiidae). Four species are Hawaiian endemics, the fifth shared with islands in the western tropical Pacific Ocean. All genera are represented widely across the Indo‐west Pacific. All five species are present on all of the major Hawaiian islands. All five species are amphidromous – their larval and early juvenile life being spent in the sea. Although there has been some local phyletic evolution to produce Hawaiian endemics, there has been no local radiation to produce single‐island endemics across the archipelago. Nor is there evidence for genetic structuring among populations in the various islands. Main conclusions In this regard, the freshwater fish fauna of Hawaii differs from the well‐known patterns of local evolution and radiation in Hawaiian Island terrestrial taxa. Amphidromy probably explains the biogeographical idiosyncrasies of the fish fauna – dispersal through the sea initially brought the fish species to Hawaii, and gene flow among populations, across the archipelago, has hitherto inhibited the evolution of local island endemics, apparently even retarding genetic structuring on individual islands.     

The human genome structure and organization

Genetic information of human is encoded in two genomes: nuclear and mitochondrial. Both of them reflect molecular evolution of human starting from the beginning of life (about 4.5 billion years ago) until the origin of Homo sapiens species about 100,000 years ago. From this reason human genome contains some features that are common for different groups of organisms and some features that are unique for Homo sapiens. 3.2 x 10(9) base pairs of human nuclear genome are packed into 23 chromosomes of different size. The smallest chromosome - 21st contains 5 x 10(7) base pairs while the biggest one -1st contains 2.63 x 10(8) base pairs. Despite the fact that the nucleotide sequence of all chromosomes is established, the organisation of nuclear genome put still questions: for example: the exact number of genes encoded by the human genome is still unknown giving estimations from 30 to 150 thousand genes. Coding sequences represent a few percent of human nuclear genome. The majority of the genome is represented by repetitiVe sequences (about 50%) and noncoding unique sequences. This part of the genome is frequently wrongly called "junk DNA". The distribution of genes on chromosomes is irregular, DNA fragments containing low percentage of GC pairs code lower number of genes than the fragments of high percentage of GC pairs.     

The status of the Irish freshwater fish fauna: a review

The status of the Irish freshwater fish fauna is reviewed. Of the 25 Irish species, 11 are introduced and five are considered as endangered or vulnerable. Agriculture through eutrophication, farm wastes and overgrazing, and afforestation and introductions are the main threats to the native fauna.     

The history of the formation of fish parasite fauna in lake Baikal

The fauna of fish parasites in Lake Baikal is represented by 5 faunistic complexes, namely the boreal plain, boreal submountain, arctic freshwater, Baikal, and Sino-Indian ones. The parasites of the boreal plain complex are dominant by the number of species (43 %). Hypotheses on the origin of the recent fish and parasite faunas of Lake Baikal were advanced on the base of the data on the parasite species composition and their distribution among hosts, as well as on the base of paleontological data. It is shown that invasion of new fish species and their parasites to Baikal led to the change of the composition of natural faunistic fish complexes and parasite systems. Invading fishes play the roles of intermediate and definitive hosts in parasite systems of Baikal, that led to the change of the initial structure of these systems.     

Characteristics of the introduced fish fauna of Israel

Fishes have been introduced worldwide with deleterious effects on various native ecosystems. To gain insight into this phenomenon in Israel, we studied the introduced ichthyofauna. There are 27 species of introduced fishes in the freshwater habitats of Israel, a large number for a nation this size. Ten of these species reproduce in the wild. Most of these fishes were introduced for aquaculture; some are constantly restocked. The proportion of restocked versus established species in Israel is high compared to other regions. New fish introductions continue in recent decades, unlike the global trend. In Israel these species are found in the Jordan Basin, Lake Kinneret (Sea of Galilee), and the coastal plain rivers. A few species are widespread, and most are found in Lake Kinneret. Harmful effects of introduced fishes have been suspected and in several cases demonstrated. We encourage further caution when new introductions are contemplated; in some regions eradication should be attempted.