Panbiogeographical analysis of Costa Rican freshwater fishes

Track analysis and Parsimony analysis of endemicity (PAE) were performed to analyze the distribution pattern of Costa Rican freshwater fishes. A basic matrix (presence/absence) was prepared using the distribution of 77 freshwater fish. The data were analyzed with CLIQUE software in order to find generalized tracks (cliques). Data also were analyzed with the software NONA and Winclada version 1.00.08 in order to perform the Parsimony Analysis of Endemicity (PAE). Fourteen equally probable cliques were found with 31 species in each and the intersection of the amount was selected as a generalized track dividing the country in two main zones: Atlantic slope from Matina to Lake Nicaragua and Pacific slope from the Coto River to the basin of the Tempisque River connected with some branches oriented to the central part of the country. PAE analysis found ten cladogram areas (72 steps, CI=0.45, RI=0.64), using the "strict consensus option" two grouping zones were identified: Atlantic slope and Pacific slope. Both PAE and Track Analysis show the division of the two slopes and the orientation of the generalized track suggests new biogeographical evidence on the influence of both old and new southern elements to explain the migrations of freshwater fish into Central America during two different geological events.     

Fishes of the Cabo Pulmo reef, Gulf of California, Mexico: systematic list and aspects of abundance and biogeography

The Cabo Pulmo reef is the most important coral formation of the Gulf of California; however, its ichthyological fauna has been poorly studied. To produce a systematic list with data on relative abundance and frequency, and biogeographical affinities, we relied on visual census, field observations, analysis of commercial and sport fisheries (from 1986 to 1998), and the literature. A total of 236 species have been recorded at Cabo Pulmo (155 genera and 60 families). This number doubles previous compilations and represents 65.1% of all reef fishes known from the Gulf of California, and about 35% of its entire shallow-water fishes. Of the total species number, 68.3% are from the Panamic Province, 11.0% Indo Pacific colonizers and the same percentage gulf endemics, 7.6% are circumtropical, 1.7% Atlantic and 0.5% cosmopolitan; none are endemic to the reef. The most abundant taxa are the labrids Thalassoma lucasanum, T. grammaticum and the pomacentrid Chromis atrilobata. Only eleven species (4.7% of total) appeared in 75% to 100% of census, and 36 (15.3% of total) had high levels of both abundance and frequency, evidencing that the community is dominated by few taxa. Local species richness exceeds the number reported for most rocky or coral reefs of the Pacific coast of México, and indicates that Cabo Pulmo is a key area in the gulf and the entire Mexican Pacific, from the ichthyological point of view.     

A hierarchical classification of freshwater mussel diversity in North America

Aim North America harbours the most diverse freshwater mussel fauna on Earth. This fauna has high endemism at the continental scale and within individual river systems. Previous faunal classifications for North America were based on intuitive, subjective assessments of species distributions, primarily the occurrence of endemic species, and do not portray continent‐wide patterns of faunal similarity. The aim of this study is to provide an analytical portrayal of patterns of mussel diversity in a hierarchical framework that informs the biogeographical history of the fauna. Location The study considered the mussel fauna of North America from the Rio Grande system northwards. Methods Patterns of mussel faunal similarity in 126 river systems or lake watersheds across North America were examined. The dataset was developed from the literature and consisted of recent species presence/absence (282 species) in each drainage unit; subspecies were not included. Patterns of mussel diversity were examined with hierarchical cluster analysis, based on a pairwise distance matrix between all drainage units. Results Cluster analysis revealed 17 faunal provinces within four major faunal regions: Mississippian, Atlantic, Eastern Gulf and Pacific. The Mississippian Region dominates the North American fauna with 11 provinces, including five not recognized by previous classifications: Mississippi Embayment, Upper Mississippi, Great Plains, Ohioan and Pontchartrain–Pearl–Pascagoula. Within the Eastern Gulf Region (containing three provinces), the Escambia–Choctawhatchee Province is distinctive from the Apalachicolan Province, under which it was previously subsumed. Patterns of diversity in the Atlantic Region (two provinces) and Pacific Region (one province) were similar to previous classifications. Main conclusions The classification proposed in this study largely corroborates earlier schemes based on the occurrence of endemic species but identifies additional heterogeneity that reflects unique assemblages of widely distributed species. The study proposes a hierarchical structure that illustrates relationships among these provinces. Although some provinces in the Mississippian Region have high endemism, all Mississippian provinces share a group of widely distributed species. The Atlantic and Eastern Gulf regions have distinctive, endemic faunas suggesting limited past connectivity with the Mississippian Region. The Pacific Region is the most distinct fauna in North America and bears close affinity to the Eurasian mussel fauna.     

Probing diversity in freshwater fishes from Mexico and Guatemala with DNA barcodes

The freshwater fish fauna of Mexico and Guatemala is exceptionally diverse with >600 species, many endemic. In this study, patterns of sequence divergence were analysed in representatives of this fauna using cytochrome c oxidase subunit 1 (COI) DNA barcodes for 61 species in 36 genera. The average divergence among conspecific individuals was 0·45%, while congeneric taxa showed 5·1% divergence. Three species of Poblana , each occupying a different crater lake in the arid regions of Central Mexico, have had a controversial taxonomic history but are usually regarded as endemics to a single lake. They possess identical COI barcodes, suggesting a very recent history of isolation. Representatives of the Cichlidae, a complex and poorly understood family, were well discriminated by barcodes. Many species of Characidae seem to be young, with low divergence values (<2%), but nevertheless, clear barcode clusters were apparent in the Bramocharax – Astyanax complex. The symbranchid, Opisthernon aenigmaticum , has been regarded as a single species ranging from Guatemala to Mexico, but it includes two deeply divergent barcode lineages, one a possible new endemic species. Aside from these special cases, the results confirm that DNA barcodes will be highly effective in discriminating freshwater fishes from Central America and that a comprehensive analysis will provide new important insights for understanding diversity of this fauna.     

Biogeography of the Tropical Eastern Pacific: distribution and phylogeny of chaenopsid fishes

The Tropical Eastern Pacific Biogeographic Region (TEP) is delimited by steep thermal gradients to the north and south, by a wide expanse of open ocean (the East Pacific Barrier) to the west, and by the Central American land mass to the east. Four provinces within the TEP have been recognized based on the distribution of rocky shore fishes and marine invertebrates: the Cortez, Mexican, Panamic, and Galápagos Provinces. For rocky shore fishes, hypothesized barriers between these provinces are areas lacking rocky outcroppings, specifically the Central American Gap between the Panamic and Mexican Provinces, the Sinaloan Gap between the Mexican and Cortez Provinces, and the Pelagic Gap between the mainland and the Islas Galápagos. The occurrence of 33 chaenopsid fish species within these provinces, as well as other oceanic islands or archipelagos in the TEP (Isla de Malpelo, Isla del Coco, and Islas Revillagigedo) were tallied based on literature records and observations of museum specimens. Chaenopsid distributions within the TEP support these hypothesized provinces and their intervening gaps. Twenty‐one species (64% of the TEP chaenopsid fauna) are restricted to a single mainland province or one of the oceanic islands or archipelagos. Of the mainland provinces, the Cortez and Panamic exhibit similar levels of endemism (50%), but the Mexican Province has only one endemic (10%). Of the remaining chaenopsids in the Mexican Province, three are widespread, occurring in all three mainland provinces, four are shared only with the Cortez Province, and two are shared only with the Panamic Province. Within the TEP, the Pelagic Gap is the most effective (crossed by only 3 of 33 species adjacent to it), followed by the Central American Gap (crossed by 5 of 21 species), and the Sinaloan Gap (crossed by 7 of 17 species). Only one species, Chaenopsis alepidota, which is found off southern California and in the Cortez Province, crosses a barrier delimiting the TEP. Species‐level phylogenetic hypotheses for the Chaenopsidae imply exclusively allopatric speciation for these fishes in the TEP. Of the barriers delimiting the TEP, the most important in the recent evolution of chaenopsids is the Isthmian Barrier which is implicated in six speciation events. Within the TEP, the Central American Gap and Sinaloan Gap are each implicated in three speciation events, while the Pelagic Gap is implicated in three speciation events of island endemics from mainland populations and one inter‐island speciation event.     

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.     

Phytogeography of the trees of the Osa Peninsula,Costa Rica

A phytogeographic analysis of the distributions of 454 species of trees native to the Osa Peninsula in 22 families revealed that 4.8% of the species are endemic to the Osa Peninsula and the adjacent mainland of Costa Rica. However, nearly one-fourth of the species might be regionally endemic to Central-South Mesoamerica (Costa Rica, Nicaragua, and Panama). Our sample suggests that 53.6% of the species occur in some part of Mesoamerica and sometimes range into northwestern South America, and that 44.5% of the species have wide distributions throughout tropical America. There is a strong affinity with the flora of northwestern South America, with 46.2% of the species on the Osa also found there. In addition, 50.6% of the tree species on the Osa occur on both the Atlantic and Pacific slopes of Central America or, if they reach South America, are sometimes found on both sides of the Andes. Major contributions to the tree flora of the Osa have been made by species arriving in the Osa by 1) dispersal from South and North America to islands in proto Central America before the formation of a dry-land connection between the two continents, and 2) migration from South America and North America after the closure of the Panamanian isthmus was made. This analysis demonstrates the importance of the Osa as a regional refuge for protecting species with distributions limited to the Osa and parts of Panama, Costa Rica, or Nicaragua. The Osa is also important because it harbors the last expanse of tropical wet forest on the Pacific slope of Central America large enough to ensure the survival of the Central American populations of widely distributed plants and animals.     

A new species of arboreal pitviper from the Atlantic versant of northern Central America

A new species of green, prehensile-tailed pitviper of the genus Bothriechis is described from the Atlantic slopes of eastern Guatemala and western Honduras. This species appears to be most closely related to B. bicolor of the Pacific versant of Chiapas (Mexico) and Guatemala. Several other species of Bothriechis occur on the Atlantic versant of northern Central America, including two montane species, B. aurifer and B. marchi but, with one possible exception, these are not known to be sympatric with the new species and occur in different mountain ranges. The widespread B. schlegelii occurs up to at least 900 m on the Sierra de Caral, where the lowest elevation recorded for the new species is 885 m.     

A synopsis of Central American Theophrastaceae

A synoptical revision of the Theophrastaceae in Central America is presented. Three genera are recognized, viz. Clavija (5 spp.), Deherainia (2 spp.), and Jacquinia (11 spp.). Four taxa are described as new to science, viz. Clavija fusca (Panama), Jacquinia nitida (Nicaragua, Honduras, Guatemala), J. montana (Nicaragua), and Deherainia smaragdina ssp. occidentals (Mexico, Veracruz). Three new combinations are proposed, viz. Clavija mezii ssp. allenii, Jacquinia macrocarpa ssp. pungens , and J. m. ssp. panamensis. Variation in reproductive characters, indumentum, and foliar anatomy is briefly reviewed.     

广西野生淡水鱼类的物种多样性及其资源的可持续利用

广西地形复杂,河流众多,适于不同鱼类的栖息和繁殖.经对分布于广西境内的各水系鱼类资源的调查、对相关馆藏标本的进一步鉴定以及对相关文献的整理,目前已知广西淡水鱼类15目37科143属290种和亚种,其中很多种类具有重要经济价值.对广西及其邻近省区鱼类多样性指数的计算、比较和分析表明,广西地区G指数最高,F指数和G-F指数除低于云南外,高于广东、海南、贵州和湖南.广西野生淡水鱼类的显著特点是物种多样性高,特有属、种多,很多物种分布区狭窄,区系成分表现出明显的东洋界特点,不同水系鱼类组成各具特色.近年来,广西自然水域的野生鱼类资源的破坏较为严重,本文对广西野生淡水鱼类资源的可持续利用进行了讨论.     

Regional endemism and cryptic species revealed by molecular and morphological analysis of a widespread species of Neotropical catfish

The lower Central American landscape was fully emergent approximately three million years ago, an event which marked the beginning of the Great American biotic interchange. Freshwater fishes participated in the biotic interchange. Because primary freshwater fishes are restricted to freshwater, they provide an excellent system for investigating the interplay of historical and recent processes on the assembly, structure and diversity of the regions' aquatic ecosystems. We focused on examining the history of diversification for a species of catfish (Pimelodella chagresi) whose distribution spans multiple, isolated drainage basins across the Isthmian landscape and into north-western South America. Analysis of mitochondrial DNA haplotypes and morphological traits indicated that P. chagresi, as currently recognized, comprises a species complex. In addition, along the Pacific slope of Panama, repeated dispersion, diversification, extinction and possibly hybridization are thought to underlie a complex distribution of haplotypes. Overall, the results underscore the tremendous importance of historical processes on regional biodiversity.     

Biogeography,habitat transitions and hybridization in a radiation of South American silverside fishes revealed by mitochondrial and genomic RAD data

Rivers and lake systems in the southern cone of South America have been widely influenced by historical glaciations, carrying important implications for the evolution of aquatic organisms, including prompting transitions between marine and freshwater habitats and by triggering hybridization among incipient species via waterway connectivity and stream capture events. Silverside fishes (Odontesthes) in the region comprise a radiation of 19 marine and freshwater species that have been hypothesized on the basis of morphological or mitochondrial DNA data to have either transitioned repeatedly into continental waters from the sea or colonized marine habitats following freshwater diversification. New double digest restriction‐site associated DNA data presented here provide a robust framework to investigate the biogeographical history of and habitat transitions in Odontesthes. We show that Odontesthes silversides originally diversified in the Pacific but independently colonized the Atlantic three times, producing three independent marine‐to‐freshwater transitions. Our results also indicate recent introgression of marine mitochondrial haplotypes into two freshwater clades, with more recurring instances of hybridization among Atlantic‐ versus Pacific‐slope species. In Pacific freshwater drainages, hybridization with a marine species appears to be geographically isolated and may be related to glaciation events. Substantial structural differences of estuarine gradients between these two geographical areas may have influenced the frequency, intensity and evolutionary effects of hybridization events.     

Possible Ballast Water Transfer of Lionfish to the Eastern Pacific Ocean

The Indo-Pacific Red Lionfish was first reported off the Florida coast in 1985, following which it has spread across much of the SE USA, Gulf of Mexico, and Caribbean Sea. Lionfish negatively impact fish and invertebrate assemblages and abundances, thus further spread is cause for concern. To date, the fish has not been reported on the Pacific coast of North or Central America. Here we examine the possibility of ballast water transfer of lionfish from colonized areas in the Atlantic Ocean to USA ports on the Pacific coast. Over an eight-year period, we documented 27 commercial vessel-trips in which ballast water was loaded in colonized sites and later discharged untreated into Pacific coast ports in the USA. California had the highest number of discharges including San Francisco Bay and Los Angeles-Long Beach. A species distribution model suggests that the probability of lionfish establishment is low for the western USA, Colombia and Panama, low to medium for Costa Rica, Nicaragua, El Salvador and Guatemala, medium to high for mainland Ecuador, and very high for western Mexico, Peru and the Galapagos Islands. Given the species’ intolerance of freshwater conditions, we propose that ballast water exchange be conducted in Gatún Lake, Panama for western-bound vessels carrying ‘risky’ ballast water to prevent invasion of the eastern Pacific Ocean.     

The biogeography of lower Mesoamerican freshwater fishes

Aim This paper examines the importance of regional processes in determining the patterns of distribution and diversity of lower Mesoamerican freshwater fishes. Location We focused our analyses on the lower Mesoamerican region, which we define to include all the rivers of Panama and Costa Rica. The geographic boundaries are the Colombian Choco to the south and Lake Nicaragua to the north. Methods We described the biogeographical provinces of lower Mesoamerica (LMA) using presence/absence data of primary and secondary LMA freshwater fishes. We conducted subsequent analyses at the spatial resolution of the biogeographical provinces and described patterns of community composition, species richness, endemism, range size, and the permeability of dispersal barriers between biogeographical provinces. Results This study represents the first attempt since that of W. A. Bussing in 1976 to investigate the biogeographical regions of Mesoamerica, and our analyses demonstrate increased regional complexity in biodiversity patterns relative to previous studies. Changes in community composition across LMA clearly highlight the importance of both extrinsic geological processes and intrinsic biological differences among freshwater fish species in shaping the dispersal and diversification histories of the LMA freshwater fish fauna. The influence of biology and geology is also exemplified by patterns of endemism and turnover between biogeographical provinces, which suggests that the relative importance of regional speciation and dispersal varies spatially across the LMA landscape. Finally, it would seem to follow that secondary freshwater fishes will have larger range sizes than primary fishes as a result of the increased salinity tolerance posited for the former group, and thus the increased probability of dispersal along coastlines. We did not, however, find a significant difference between the average range size of primary and secondary freshwater fishes, indicating that the putative differences in physiological tolerance to seawater between the two groups are not reflected in their distribution patterns at the scale of LMA. The geometric distribution of range size of LMA freshwater fishes suggests that dispersal of both primary and secondary freshwater fishes along coastlines must be infrequent. Main conclusion The observation that regional processes exerted a strong influence on the assembly and maintenance of LMA freshwater fish communities has important consequences for both theory and conservation. We suggest that large‐scale biogeographical analyses are required to illuminate the backdrop upon which local interactions play themselves out, supporting a top‐down approach to the study of biological diversity. Our results also identify areas of high conservation priority, providing a baseline for informing conservation strategies for freshwater fishes in LMA. We conclude by calling for conservation planning and action that acknowledges the importance that regional processes play in determining patterns of organismal diversity, and that incorporates these processes in strategies to conserve remnant biological diversity.     

Biodiversity hotspots, centres of endemicity, and the conservation of coral reefs

On land, biodiversity hotspots typically arise from concentrations of small‐range endemics. For Indo‐Pacific corals and reef fishes, however, centres of high species richness and centres of high endemicity are not concordant. Moreover ranges are not, on average, smaller inside the Central Indo‐Pacific (CI‐P) biodiversity hotspot. The disparity between richness and endemicity arises because corals and reef fishes have strongly skewed range distributions, with many species being very widespread. Consequently, the largest ranges overlap to generate peaks in species richness near the equator and the CI‐P biodiversity hotspot, with only minor contributions from endemics. Furthermore, we find no relationship between the number of coral vs. fish endemics at locations throughout the Indo‐Pacific, even though total richness of the two groups is strongly correlated. The spatial separation of centres of endemicity and biodiversity hotspots in these taxa calls for a two‐pronged management strategy to address conservation needs.     

Distributional patterns of freshwater taxa (fishes, crustaceans and plants) from the Mexican Transition Zone

Aim  To test whether distributional patterns of Neotropical freshwater taxa fit the generalized tracks already postulated for terrestrial groups occurring in the Mexican Transition Zone.
Location  The study units comprised 17 hydrological basins located along the Pacific coast of the Americas from Mexico to Panama, and in the Gulf of Mexico from the Papaloapan to the Grijalva–Usumacinta basin.
Methods  Distributional data for 22 fish species, 34 crab species of the tribe Pseudothelphusini, and 22 strictly freshwater species of angiosperms were analysed. Parsimony analysis of endemicity is based on presence/absence data of these taxa and uses the computer programs Winclada and NONA.
Results  Three generalized tracks were obtained: (1) Mexican North Pacific, (2) Mexican Central Pacific, and (3) Southern Mexico–Guatemala. A node resulted at the intersection of the first two tracks, coinciding with the Neovolcanic Axis in central Mexico.
Main conclusions  Freshwater generalized tracks with an altitudinal distribution below 1000 m, mainly including fishes and angiosperms, are close to the Tropical Mesoamerican generalized track. Generalized tracks above 1000 m, including freshwater crabs, have a stronger affinity with the Mountain Mesoamerican track. The Isthmus of Tehuantepec represents a node for the Neotropical freshwater and terrestrial biota. These results seem to indicate that common geobiotic processes have induced these patterns.