Microsatellite markers for the cardinal tetra Paracheirodon axelrodi,a commercially important fish from central Amazonia

The cardinal tetra Paracheirodon axelrodi is a very popular aquarium fish and the most important ornamental fishery resource for riverine communities inhabiting the Rio Negro floodplain in central Amazonia. Here we describe the isolation and characterization of 14 microsatellite DNA loci for cardinal tetras. Number of alleles and heterozygosity per locus in a sample of 30 fish ranged from 2 to 22 and from 0.49 to 0.92, respectively. These markers provide powerful tools for studies on conservation and management of cardinal tetra resources and for investigating evolutionary processes underlying population diversification in Amazonian flooded forest fishes.     

Characterization of microsatellite loci for the Amazonian rummy‐nose tetra,Hemigrammus bleheri (Teleostei,Characidae)

The rummy‐nose tetra, Hemigrammus bleheri, is a small fish found in forest streams of the Rio Negro floodplain, central Amazonia. This species is popular in aquaria and used as an ornamental fishery resource by the riverine people from middle Rio Negro. Here we describe eight microsatellite DNA loci for rummy‐nose tetras. Number of alleles and heterozygosity per locus in a sample of 30 fish ranged from five to 22 and from 0.52 to 0.96, respectively. These highly variable genetic markers provide important tools for investigating population history and identifying conservation units in rummy‐nose tetras.     

Population history of the Amazonian one-lined pencilfish based on intron DNA data

The evolutionary history of Amazonian organisms is generally poorly understood. This is particularly true for small floodplain fish species that show reduced dispersal capabilities. The one-lined pencilfish Nannostomus unifasciatus (family Lebiasinidae) is a small fish found in flooded forests of the Rio Negro Floodplain (RNF) in central Amazonia, Brazil. We used a large number of samples collected throughout the species distribution in the RNF and in its headwaters and DNA data from the second intron of the S7 ribosomal protein to reconstruct the phylogeography of N. unifasciatus . Two markedly distinct phylogroups of N. unifasciatus were detected in the RNF. Although these lineages are largely allopatric, they remain reproductively isolated in regions where they overlap, suggesting cryptic speciation in this group in the Rio Negro basin. Coalescent-based statistical methods suggest that the history of these populations was dominated by a Miocene fragmentation of the species in the headwaters of the basin that originated the two phylogroups, followed by recent events of demographic and range expansions in the floodplain. This pattern is discussed within the context of the geomorphologic history of the region, especially geotectonics, and of marine incursions. Our results match the predictions of the palaeogeography hypothesis of speciation and outline the usefulness of an intron DNA marker to reconstruct population history of a central Amazonian fish. Because N. unifasciatus is harvested commercially in the ornamental fishery of the RNF, the two species and limited dispersal capacity between nearby populations identified here are also important to develop sound management decisions in the region.     

Patterns of ion regulation in acidophilic fish native to the ion-poor, acidic Rio Negro

The Na⁺ uptake mechanism of cardinal tetras Paracheirodon axelrodi displayed specialization for operation in dilute waters of the amazonian Rio Negro. Kinetic analysis revealed low K_m and high J_max values which ensure high rates of uptake even in very dilute waters. In contrast, Na⁺ uptake of angelfish Pterophyllum scalare did not appear to be specialized for dilute waters at all, with much higher K_m and lower J_max values. Na⁺ uptake in cardinal tetras was high and completely unaffected down to pH 3·5, while uptake in angelfish was much lower and progressively inhibited by dropping pH; it was completely shut down at pH 3·5. During chronic exposure to pH 4·0 and 3·5, angelfish showed no ability to restore Na⁺ uptake and at pH 3·5 all individuals died between day 3 and 6 presumably due to small, but steady loss of Na⁺. At low pH, both species displayed a strong ability to prevent stimulation of diffusive Na+ losses. In angelfish, the ability to control diffusive ion losses at low pH was related to a high branchial affinity for Ca²⁺. For cardinal tetras, the rate of Na⁺ loss appeared to be independent of water Ca²⁺ concentration. The specializations of cardinal tetras are similar to other characid fishes tested, but the results for angelfish reveal a new pattern of ion regulation in acidophilic species from the Rio Negro. The differences between the species may be the result of their different distributions, cardinal tetras are found in the central Rio Negro region while angelfish are more peripheral, or they may reflect phylogenetic differences.     

Transalpine colonisation and partial phylogeographic erosion by dispersal in the common vole (Microtus arvalis)

The colonisation history and genetic structure of the common vole ( Microtus arvalis ) was investigated in the region of the Alps by analysing the mitochondrial cytochrome b gene (mtDNA) and 19 microsatellite loci (nucDNA) for 137 voles from 52 localities. mtDNA data provided a much refined distribution of three highly divergent evolutionary lineages in the region compared to previous studies. Although high mountain ranges are widely accepted to be barriers for colonisation processes for many organisms and especially small terrestrial mammals, our phylogeographic analyses showed clear evidence of four transalpine colonisation events by the common vole. Individual-based phylogenetic analyses of nucDNA and two alternative Bayesian-clustering approaches revealed a deep genetic structure analogous to mtDNA. Incongruence between nucDNA and mtDNA at the individual level was restricted to the regions of contact between the lineages. mtDNA patterns and strong female philopatry in M. arvalis suggest that the crossings of the Alps occurred during the colonisation of the region when it was free from ice after the last glaciation. nucDNA patterns suggest that some of the transalpine elements of this phylogeographic pattern were subsequently eroded by male-biased gene flow. We conclude that the combination of phylogeography and landscape genetics at the individual level can provide very detailed insights into colonisation events and may even allow differentiation between historical and more recent processes.     

Three fishes in one: cryptic species in an Amazonian floodplain forest specialist

Accurately describing biodiversity in tropical regions such as Amazonia is difficult because of insufficient morphological inventories and the lack of studies on the distribution of genetic diversity. Aquatic organisms from Amazonian flooded forests are generally expected to move laterally along the forests during the annual inundation cycle, a behaviour that should promote admixture of populations and reduce within‐drainage speciation. We used an unprecedented fine‐scale sampling effort and multiple DNA markers to quantify region‐wide population differentiation in an Amazonian floodplain forest specialist, the black‐wing hatchet fish Carnegiella marthae ( Myers, 1927 ). Our study revealed three previously unsuspected and ancient cryptic species of black‐wing hatchet fish in the Rio Negro floodplain (RNF), in central Amazonia. Two species produce occasional first‐generation hybrids. The third and rarer species, although found in extreme sympatry with another species, appears to be reproductively isolated, and also differs in external morphology and dentition. Our findings have important implications for guiding conservation management because C. marthae is harvested commercially in the RNF ornamental fishery. They also suggest that the diversity of Amazonian ichthyofauna is vastly underestimated, including that found in landscapes lacking contemporary barriers to account for population divergence and speciation. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 391–403.     

Development and characterization of microsatellite markers for the Amazonian blackwing hatchetfish,Carnegiella marthae (Teleostei,Gasteropelecidae)

The blackwing hatchetfish, Carnegiella marthae, is a small characin species distributed in forest streams of the Negro and upper Orinoco River basins in Amazonia. Freshwater hatchetfish are popular in the aquarium trade and represent an economic resource for the riverine people from middle Rio Negro, in Brazil. We isolated and characterized seven microsatellite DNA loci for the blackwing hatchetfish. Number of alleles and heterozygosity per locus in a sample of 30 fish ranged from three to 17 and from 0.19 to 0.87, respectively. These microsatellite loci provide powerful markers for studies on taxonomy, management and phylogeographic history of Amazonian hatchetfish.     

Molecular signature of the D-loop in the brown pencilfish Nannostomus eques (Characiformes, Lebiasinidae) reveals at least two evolutionary units in the Rio Negro basin, Brazil

The genetic variability of the brown pencilfish Nannostomus eques was studied, based on an analysis of sequences from the control region (1084 bp) of mitochondrial (mt)DNA in 125 individuals collected from eight tributaries along the upper (Açaituba, Miuá, Jaradi and Arixanã), middle (Demini), and lower (Jacundá, Maguari and Catalão) Rio Negro (Brazil). Phylogenetic inferences using mtDNA data from N. eques revealed two evolutionary units. Genetic distance between them ranged from 5·5 to 8·3% and differed by 8·5–11·8% from the sister species pencilfish Nannostomus unifasciatus. The time of divergence between the two evolutionary units was estimated to be the Middle Pliocene (c. 2·99 million years before present). Population genetic analysis (DNA polymorphism, AMOVA and Mantel test) showed high haplotype diversity (HD, >0·90) in each evolutionary unit, a strong population genetic structure in the Demini River that formed a monophyletic group and a correlation between genetic divergence and geographical distance in only one of these units (evolutionary unit 1). On the basis of molecular data, the rapids and waterfalls near São Gabriel da Cachoeira (Upper Rio Negro) were the main barriers to gene flow within evolutionary unit 1 in some localities. The emergences of the Branco River and the Anavilhanas Archipelago were apparently responsible for the discrepancy in distribution of the two evolutionary units, except at Jacundá, where the evolutionary units were sympatric. In view of the differences between the evolutionary units, N. eques cannot be treated as a single stock in the Rio Negro basin. These results may have important implications for the fishery management of this ornamental fish.     

Contrasting patterns of genetic structure in Caryocar (Caryocaraceae) congeners from flooded and upland Amazonian forests

In the present study, we compare the genetic structure of a flooded forest tree Caryocar microcarpum and a terra firme forest tree Caryocar villosum in the lower Rio Negro region and test the hypothesis that the Rio Negro, the largest tributary on the left bank of the Amazon River, has been acting as a geographical barrier to gene flow between populations from the left and right banks. Seventeen adult individuals on the left bank and 27 on the right bank of Rio Negro were sampled for C. microcarpum, whereas 27 on the left and 20 on the right bank were sampled for C. villosum. Two chloroplast DNA regions were sequenced: the intron of trnL gene and the intergenic region between psbA and trnH genes; and all individuals were genotyped using ten microsatellite loci. The trnL intron and psbA‐trnH intergenic spacer generated fragments of 459 bp and 424 bp, respectively. For C. microcarpum, six haplotypes were identified for trnL and seven for psbA‐trnH. By contrast, only one haplotype was found for C. villosum for both sequences. The results obtained showed that the Rio Negro has not been a barrier to gene flow by pollen and seeds for either species. No genetic differentiation and a high migration rate between populations from the left and right banks of the Rio Negro were detected for the chloroplast sequences and nuclear microsatellites, for both C. villosum and C. microcarpum. Although the two analysed sequences showed a sharp topology difference, both indicated that multiple lineages may have contributed to the origin of C. microcarpum populations in the Rio Negro basin. Nevertheless, for C. villosum, from terra firme, the results obtained may provide evidence of a recent expansion of one maternal lineage from an ancient relic population surviving in one of the few moist forest refuges of the Guiana Shield during extended droughts of the glacial periods. We hypothesize that the contrasting environments colonized by this congener pair may have played an important role in shaping the genetic structure of both species. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98 , 278–290.     

Vicariance, colonisation, and fast local speciation in Asia Minor and the Balkans as revealed from the phylogeny of spined loaches (Osteichthyes; Cobitidae)

We reconstruct the phylogeny of the morphologically diagnosable subgenera Bicanestrinia, Beysehiria, and Cobitis sensu stricto of the genus Cobitis from Asia Minor and the Balkans. We used the complete cytochrome b gene of 65 specimens in order to infer their evolutionary history in this zoogeographically interesting area. Our phylogeographic analysis did not evidence the previously suggested monophyly of the Bicanestrinia subgenus but revealed five monophyletic lineages in the area: the lineages Bicanestrinia I-IV including all species of Bicanestrinia plus the lineage Cobitis s. str. The monotypic subgenus Beysehiria from Lake Beysehir in Anatolia was closely related to the syntopic population of C. turcica and nested inside the lineage Bicanestrinia III. The strictly allopatric distribution of the four lineages of Bicanestrinia suggests that vicariance has played a major role in the diversification of Bicanestrinia. All analysed species of Cobitis s. str. from Asia Minor and Balkans were closely related to Cobitis s. str. from Central Europe, the Danube basin and the Caucasus, indicating at least two colonisation events into Asia Minor and the Balkans. A third, recent colonisation event led to the presence of C. strumicae, generally restricted to the Aegean Sea drainage, in the Danube basin. Besides the evidences of vicariance and colonisation events in the phylogenetic history of the genus Cobitis in Asia Minor and the Balkans, our analysis suggested also a rapid morphological evolution of C. bilseli in a lacustrine environment. Application of Cobitis mitochondrial cytochrome b clocks of 0.68% sequence divergence per million years (MY) suggest that the split between the five major lineages happened approximately 12.4-17.6 MYA, and according to the lack of basal resolution of this monophyletic group probably the split of all lineages happened within a narrow time window.     

Phylogeographic Analyses Suggest Multiple Lineages of Crystallaria asprella (Percidae: Etheostominae)

The crystal darter, Crystallaria asprella, exists in geographically isolated populations that may be glacial relicts from its former, wide distribution in the Eastern U.S. An initial phylogeographic survey of C. asprella based upon the mitochondrial cytochrome b (cyt b) gene indicated that there were at least four distinct populations within the species: Ohio River basin, Upper Mississippi River, Gulf coast, and lower Mississippi River. In particular, the most divergent population was the most recently discovered, from the Elk River, WV, in the Ohio River basin, and it was postulated that this population represents an undescribed, potentially threatened species. However, differentiation observed at a single gene region is generally not considered sufficient evidence to establish taxonomic status. In the present study, nucleotide variation at the mitochondrial control region and a nuclear S7 ribosomal gene intron were compared to provide independent verification of phylogeographic results between individuals collected from the same five disjunct populations previously surveyed. Variation between populations at the control region was substantial (except between Gulf drainages) and was concordant with patterns of sequence divergence from cyt b. Only the Elk River population was resolved as monophyletic based upon nuclear S7, but significant differences based upon Φ_ST statistics were observed between most populations. Morphometric data were consistent with molecular data regarding the distinctiveness of the Elk River population. It is proposed that populations of C. asprella consist of at least four distinct population segments, and that the Elk River group likely constitutes a distinct species.     

Past climate change drives current genetic structure of an endangered freshwater mussel species

Historical‐to‐recent climate change and anthropogenic disturbance affect species distributions and genetic structure. The Rio Grande watershed of the United States and Mexico encompasses ecosystems that are intensively exploited, resulting in substantial degradation of aquatic habitats. While significant anthropogenic disturbances in the Rio Grande are recent, inhospitable conditions for freshwater organisms likely existed prior to such disturbances. A combination of anthropogenic and past climate factors may contribute to current distributions of aquatic fauna in the Rio Grande basin. We used mitochondrial DNA and 18 microsatellite loci to infer evolutionary history and genetic structure of an endangered freshwater mussel, Popenaias popeii, throughout the Rio Grande drainage. We estimated spatial connectivity and gene flow across extant populations of P. popeii and used ecological niche models (ENMs) and approximate Bayesian computation (ABC) to infer its evolutionary history during the Pleistocene. structure results recovered regional and local population clusters in the Rio Grande. ENMs predicted drastic reductions in suitable habitat during the last glacial maximum. ABC analyses suggested that regional population structure likely arose in this species during the mid‐to‐late Pleistocene and was followed by a late Pleistocene population bottleneck in New Mexico populations. The local population structure arose relatively recently, perhaps due to anthropogenic factors. Popenaias popeii, one of the few freshwater mussel species native to the Rio Grande basin, is a case study for understanding how both geological and anthropogenic factors shape current population genetic structure. Conservation strategies for this species should account for the fragmented nature of contemporary populations.     

Molecular evidence for a recent demographic expansion in the puma (Puma concolor) (Mammalia,Felidae)

The puma is an iconic predator that ranges throughout the Americas, occupying diverse habitats. Previous phylogeographic analyses have revealed that it exhibits moderate levels of genetic structure across its range, with few of the classically recognized subspecies being supported as distinct demographic units. Moreover, most of the species’ molecular diversity was found to be in South America. To further investigate the phylogeographic structure and demographic history of pumas we analyzed mtDNA sequences from 186 individuals sampled throughout their range, with emphasis on South America. Our objectives were to refine the phylogeographic assessment within South America and to investigate the demographic history of pumas using a coalescent approach. Our results extend previous phylogeographic findings, reassessing the delimitation of historical population units in South America and demonstrating that this species experienced a considerable demographic expansion in the Holocene, ca. 8,000 years ago. Our analyses indicate that this expansion occurred in South America, prior to the hypothesized re-colonization of North America, which was therefore inferred to be even more recent. The estimated demographic history supports the interpretation that pumas suffered a severe demographic decline in the Late Pleistocene throughout their distribution, followed by population expansion and re-colonization of the range, initiating from South America.     

Inter‐basin exchange and repeated headwater capture across the Sierra Madre Occidental inferred from the phylogeography of Mexican stonerollers

Aim Geomorphic evolution of river basins can shape the structure and diversity of aquatic communities, but understanding the biological significance of basin evolution can be challenging in semi‐arid regions with ephemeral or endorheic conditions and complex drainage configurations such as the Sierra Madre Occidental (SMO) in North America. In this study, we characterized range‐wide patterns of genetic variation in the Mexican stoneroller (Campostoma ornatum) to infer how orogenic and erosional influences on river basin connectivity have given rise to the diverse and largely endemic freshwater communities across the SMO region. Location Twelve drainage basins across northern Mexico and the south‐western United States, centred on the SMO. Methods  We collected 202 specimens from 98 localities across the range of C. ornatum. We performed phylogenetic analyses of DNA sequences from one mitochondrial (cytochrome b) and one nuclear (intron S7) gene. Phylogenetic trees were estimated for each data set using maximum likelihood and Bayesian inference. Results Phylogenetic analyses consistently resolved a monophyletic C. ornatum composed of multiple evolutionary lineages within two markedly divergent clades that differentiate northern drainages from southern drainages in the SMO region. Within‐clade patterns of divergence corresponded to fine‐scale geographic structure within and among SMO drainage basins. However, the geographic distribution of evolutionary lineages within the northern and southern clades did not always correspond to the geographic configuration of drainage basins. Some subclades encompassed multiple drainages, and individuals from a single drainage were sometimes recovered in multiple subclades. Main conclusions Our findings indicate that a common ancestor of Mexican Campostoma is likely to have entered north‐west Mexico through an ancient Rio Grande system that extended as far south as the Rio Nazas and Rio Aguanaval. The geographic orientation of the two strongly divergent clades recovered within C. ornatum provides evidence of long‐standing isolation of southern basins from northern basins within the ancestral Rio Grande system, possibly due to the combined influence of tectonic events and increasing regional aridity. Geographic patterns of genetic variation also provide evidence of range expansion from Atlantic to Pacific drainages due to drainage evolution and river capture events, as well as further inter‐basin exchange via more recent headwater capture events, hydrological connections and possible anthropogenic introductions.     

Extremely high variability in the S72 intron of the Amazonian cardinal tetra (Paracheirodon axelrodi)

Here, a combination of a DNA screening technique, direct sequencing and cloning was used to carry out a large-scale assessment of intron variability in cardinal tetras – the first to be conducted for an Amazonian forest fish. To the best of the authors' knowledge, the levels of DNA variability reported in this study are the highest ever documented for an intron marker.     

Phylogeography and intraspecific genetic variation of prochilodontid fishes endemic to rivers of northern South America

Phylogeography and intraspecific genetic variation were studied in prochilodontids endemic to the Orinoco, Essequibo and Amazon River basins of northern South America. Portions of two protein‐encoding mitochondrial (mt) DNA genes, ND4 and COI, were examined using single‐strand conformational polymorphisms (SSCPs) and nucleotide sequencing. Phylogeographic analysis indicated that the geographically widespread Prochilodus rubrotaeniatus is paraphyletic, with individuals from the Orinoco sharing most recent common ancestry with co‐occurring Prochilodus mariae . A second Prochilodus rubrotaeniatus clade was composed of haplotypes found in the Rio Cuyuní(Essequibo Basin) and tributaries of the Rio Negro (Amazon Basin). Intraspecific genetic analysis suggested that a complex set of processes have influenced patterns of genetic variation in prochilodontid lineages. Prochilodus rubrotaeniatus is monomorphic at both loci in the Rio Negro and probably recently colonized this basin from the Rio Essequibo. Only two of 55 P. mariae exhibited variant haplotypes, and both had resulted from non‐synonymous changes in the ND4 region. These observations were counter to neutral expectation and consistent with the action of natural selection on the mitochondrion. Overall, these analyses implicate vicariance, demography and selection for driving diversification of prochilodontids in northern South America.     

Wide but not impermeable: Testing the riverine barrier hypothesis for an Amazonian plant species

Wallace's riverine barrier hypothesis postulates that large rivers, such as the Amazon and its tributaries, reduce or prevent gene flow between populations on opposite banks, leading to allopatry and areas of species endemism occupying interfluvial regions. Several studies have shown that two major tributaries, Rio Branco and Rio Negro, are important barriers to gene flow for birds, amphibians and primates. No botanical studies have considered the potential role of the Rio Branco as a barrier, while a single botanical study has evaluated the Rio Negro as a barrier. We studied an Amazon shrub, Amphirrhox longifolia (A. St.‐Hil.) Spreng (Violaceae), as a model to test the riverine barrier hypothesis. Twenty‐six populations of A. longifolia were sampled on both banks of the Rio Branco and Rio Negro in the core Amazon Basin. Double‐digest RADseq was used to identify 8,010 unlinked SNP markers from the nuclear genome of 156 individuals. Data relating to population structure support the hypothesis that the Rio Negro acted as a significant genetic barrier for A. longifolia. On the other hand, no genetic differentiation was detected among populations spanning the narrower Rio Branco, which is a tributary of the Rio Negro. This study shows that the strength of riverine barriers for Amazon plants is dependent on the width of the river separating populations and species‐specific dispersal traits. Future studies of plants with contrasting life history traits will further improve our understanding of the landscape genetics and allopatric speciation history of Amazon plant diversity.     

Molecular systematic analysis reveals cryptic tertiary diversification of a widespread tropical rain forest tree

The broad geographic range of many Neotropical rain forest tree species implies excellent dispersal abilities or range establishment that preceded the formation of current dispersal barriers. In order to initiate historical analyses of such widespread Neotropical trees, we sequenced the nuclear ribosomal spacer (ITS) region of Symphonia globulifera L. f. (Clusiaceae) from populations spanning the Neotropics and western Africa. This rain forest tree has left unmistakable Miocene fossils in Mesoamerica (15.5-18.2 Ma) and in South America ( approximately 15 Ma). Although marine dispersal of S. globulifera is considered improbable, our study establishes three marine dispersal events leading to the colonization of Mesoamerica, the Amazon basin, and the West Indies, thus supporting the paleontological data. Our phylogeographic analysis revealed the spatial extent of the three Neotropical S. globulifera clades, which represent trans-Andes (Mesoamerica+west Ecuador), cis-Andes (Amazonia+Guiana), and the West Indies. Strong phylogeographic structure found among trans-Andean populations of S. globulifera stands in contrast to an absence of ITS nucleotide variation across the Amazon basin and indicates profound regional differences in the demographic history of this rain forest tree. Drawing from these results, we provide a historical biogeographic hypothesis to account for differences in the patterns of beta diversity within Mesoamerican and Amazonian forests.     

Genetic consequences of Pleistocene glaciations for the tundra vole (Microtus oeconomus) in Beringia

Repeated glacial events during the Pleistocene fragmented and displaced populations throughout the northern continents. Different models of the effects of these climate-driven events predict distinct phylogeographic and population genetic outcomes for high-latitude faunas. The role of glaciations in (i) promoting intraspecific genetic differentiation and (ii) influencing genetic diversity was tested within a phylogeographic framework using the rodent Microtus oeconomus. The spatial focus for the study was Beringia, which spans eastern Siberia and northwestern North America, and was a continental crossroads and potential high arctic refugium during glaciations. Variation in mitochondrial DNA (cytochrome b and control region; 214 individuals) and nuclear DNA (ALDH1 intron; 63 individuals) was investigated across the Beringian region. Close genetic relationships among populations on either side of the Bering Strait are consistent with a history of periodic land connections between North America and Asia. A genetic discontinuity observed in western Beringia between members of a Central Asian clade and a Beringian clade is geographically congruent with glacial advances and with phylogeographic discontinuities identified in other organisms. Divergent island populations in southern Alaska were probably initially isolated by glacial vicariance, but subsequent differentiation has resulted from insularity. Tests of the genetic effects of postglacial colonization were largely consistent with expansion accompanied by founder effect bottlenecking, which yields reduced diversity in populations from recently deglaciated areas. Evidence that populations in the Beringian clade share a history of expansion from a low-diversity ancestral population suggests that Beringia was colonized by a small founder population from central Asia, which subsequently expanded in isolation.     

Impact of Past Forest Fires on Bird Populations in Flooded Forests of the Cuini River in the Lowland Amazon

Blackwater floodplain forests of the Rio Negro are susceptible to understory fires. Bird composition was distinct between burned and unburned floodplain forest but not between young (12–18 yr) and old burns (>25 yr), indicating low resilience after fire. Forest regeneration is slow, with open grassy areas persisting >80 yr.