Cichla Species Research Articles

Reduced genetic diversity and the success of the invasive peacock bass (Cichliformes: Cichlidae).

Several species of Cichla successfully colonized lakes and reservoirs of Brazil, since the 1960's, causing serious damage to local wildlife. In this study, 135 peacock bass were collected in a reservoir complex in order to identify if they represented a single dominant species or multiple ones, as several Cichla species have been reported in the basin. Specimens were identified by color pattern, morphometric and meristic data, and using mitochondrial markers COI, 16S rDNA and Control Region (CR). Overlapping morphological data and similar coloration patterns prevented their identification using the taxonomic keys to species identification available in the literature. However, Bayesian and maximum likelihood from sequencing data demonstrated the occurrence of a single species, Cichla kelberi. A single haplotype was observed for the 16S and CR, while three were detected for COI, with a dominant haplotype present in 98.5% of the samples. The extreme low diversity of the transplanted C. kelberi evidenced a limited number of founding maternal lineages. The success of this colonization seems to rely mainly on abiotic factors, such as increased water transparency of lentic environments that favor visual predators that along with the absence of predators, have made C. kelberi a successful invader of these reservoirs.

Development of species-specific Cichla species eDNA primers for alien invasive species (AIS) monitoring in Malaysia

Peacock bass or the cichlids are known locally as top predator fishes which are invasive in Malaysia freshwater system. Detection probabilities for these fishes are typically low, especially using conventional capture-survey method due to the fish’s behaviour of hiding beneath the water’s surface. Hence, the environmental DNA (eDNA) monitoring is a relatively new approach that can be used to assess the distribution of these invasive fishes. Here, we report the strategy to develop small fragment (280- 400 bp) specific-specific primers for three selected invasive Cichla species namely, C. ocellaris, C. monoculus, and C. kelberi based on mitochondrial DNA (mtDNA) sequences. Current research showed that the developed species-specific primers from cytochrome oxidase I (COI) gene has high resolution at species level. Species-specific amplification tests also proved the specificity of the developed primers, securing the high- level species identification potential which may help in controlling the spread of alien invasive fish species.

Comparative cytogenetic of six species of Amazonian Peacock bass (Cichla, Cichlinae): intrachromosomal variations and genetic introgression among sympatric species.

Cytogenetic data for the genus Cichla Bloch et Schneider, 1801 are still very limited, with only four karyotype descriptions to date. The sum of the available cytogenetic information for Cichla species, points to a maintenance of the diploid number of 48 acrocentric chromosomes, considered a typical ancestral feature in cichlids. In the current study, we performed molecular and classical cytogenetic analyses of the karyotype organization of six species of Cichla, the earliest-diverging genus of Neotropical cichlids. We cytogenetically analysed Cichla kelberi Kullander et Ferreira, 2006, Cichla monoculus Agassiz, 1831, Cichla piquiti Kullander et Ferreira, 2006, Cichla temensis Humboldt, 1821, Cichla vazzoleri Kullander et Ferreira, 2006 and Cichla pinima Kullander et Ferreira, 2006, including three individuals that showed mixed morphological characteristics, likely from different species, suggesting they were hybrid individuals. All individuals analysed showed 2n = 48 acrocentric chromosomes, with centromeric heterochromatic blocks on all chromosomes and a terminal heterochromatic region on the q arm of the 2nd pair. Mapping 18S rDNA gave hybridization signals, correlated with the nucleolus organizer regions, on the 2nd pair for all analyzed individuals. However, we found distinct patterns for 5S rDNA: interstitially at the proximal position on 6th pair of four species (C. kelberi, C. pinima, C. piquiti and C. vazzoleri), and on the distal of the 4th pair in two (C. monoculus and C. temensis). Accordingly, we present here new data for the genus and discuss the evolutionary trends in the karyotype of this group of fish. In addition, we provide data that supports the occurrence of hybrid individuals in the Uatumã River region, mainly based on 5S rDNA mapping.

Genomic markers confirm introgressive hybridization in Cichla (Teleostei) in an invaded coastal system

AbstractHybridization seems frequent among Cichla species (peacock bass), as studies have reported hybrids in populations within and outside their natural range (the Amazon and Orinoco river basins). Cichla kelberi and C. monoculus were introduced to the São João river (Southeast Brazil) more than 20 years ago, where they successfully colonized different environments. In this system, specimens have coloration and morphology that differ from patterns observed in their native range, indicating that the contact between C. monoculus and C. kelberi eliminated reproductive isolation, leading to introgressive hybridization. In this context, we used the LWS and dlx2 genes and the random amplified polymorphic DNA technique to characterize Cichla species in the São João river and to detect possible hybridization processes. The genetic markers identified here showed mismatches between mitochondrial and nuclear DNA in C. monoculus and C. kelberi, sampled both in the reservoir and in the estuarine stretch. Fragments of nuclear DNA from both species, as well as the presence of mitochondrial DNA from one species associated with the nuclear genome of the other, provide strong evidence of hybridization associated with bidirectional genetic introgression. Because hybrids may be more resistant, competitive, and aggressive than their parental species, these invaders may pose a significant threat to native biodiversity in this and other coastal rivers of the region.

Origin of Invasive Fish Species, Peacock Bass Cichla Species in Lake Telabak Malaysia Revealed by Mitochondrial DNA Barcoding

Origin of Invasive Fish Species, Peacock Bass Cichla Species in Lake Telabak Malaysia Revealed by Mitochondrial DNA Barcoding

Molecular and morphological approaches for species delimitation and hybridization investigations of two Cichla species

ABSTRACT The hybridization is a widely-discussed issue in several studies with fish species. For some authors, hybridization may be related with diversification and speciation of several groups, or also with the extinction of populations or species. Difficulties to differentiate species and hybrids may be a problem to correctly apply a management of wild species, because hybrid lineages, especially the advanced ones, may resemble the parental species. The genus Cichla Bloch & Schneider, 1801 constitutes an interesting experimental model, considering that hybridization and taxonomic uncertainties hinder a correct identification. Considering these problems, in this study, we developed genetic methodologies and applied meristic and morphometric approaches in wild samples in order to identify species and for test a possible hybridization between Cichla kelberi Kullander & Ferreira, 2006 and Cichla piquiti Kullander & Ferreira, 2006. For this, C. kelberi, C. piquiti and potential hybrid ( carijó) individuals were collected in Paraná and Tietê rivers (SP, Brazil). For meristic and morphometric methods, the individuals were analyzed using the statistical software Pcord 5:31, while for molecular methods, primers for PCR-multiplex were designed and enzyme for PCR-RFLP were selected, under the species-specific nucleotide. All results indicated that the carijó is not an interspecific hybrid, because it presented identical genetic pattern and morphology closed to C. piquiti. Thus, we propose that carijó is a C. piquiti morphotype. In addition, this study promotes a new molecular tool that could be used in future research, monitoring and management programs of the genus Cichla.

<b>Prospecting molecular markers to distinguish <i>Cichla kelberi</i>, <i>C. monoculus</i> and <i>C. piquiti

Peacock bass, a fish of the genus Cichla, is an exotic species from the upper river Parana floodplain in which the species Cichla kelberi and C. piquiti have been confirmed, coupled to the specie C. monoculus upstream in the Capivara and Taquarucu dams. The introduction of this genus has caused negative impacts on the diversity of native species. Current research prospects DNA sequences capable of distinguishing the three species and provide molecular data for the taxonomic characterization of the species in the upper Parana River basin. Sequencing of nuclear (tmo4c4, dlx2 and bmp4) and mitochondrial (cox1, cytb) loci were done from fish of the three species of the genus Cichla reported in the literature of the upper Parana River basin. Sequence analysis provided molecular differentiation for the species through the usage of loci cytb, dlx2 and cox1. Since the latter only distinguished C. piquiti from the other Cichla species, the loci bmp4 and tmo4c4 were not adequate to accomplish our aim.

Multi-locus species tree for the Amazonian peacock basses (Cichlidae: Cichla): Emergent phylogenetic signal despite limited nuclear variation

The inference of phylogenies of closely related species is obstructed by phenomena such as porous species boundaries and deep coalescence, and is often exacerbated by low levels of nucleotide variation among most loci surveyed in phylogenetic studies. We investigated the utility of twenty-one nuclear loci that had a range of 5–40 (median of 14) variable sites per locus to estimate the phylogeny of the genus Cichla, a group of 15 Neotropical cichlid fishes that began to diverge in the early to mid Miocene. We found that under a concatenated approach, the least variable loci, while contributing less to the overall phylogenetic signal (posterior node support), nevertheless provided information that increased support for the final tree. Moreover, this was not a result of misdirection by mutational noise, as the inference from all data was far superior to those from reduced datasets (those with more variable loci) in terms of the relative precision of posterior tree space. Phylogenetic methods that allowed each locus to have a separate genealogy, including Bayesian concordance analysis and a multispecies coalescent model, provided phylogenies that were also compatible with the concatenated tree in terms of the eight recently delimited species of Cichla, albeit with somewhat diminished support for some branches. In contrast, described species that still regularly exchange genes showed unstable relationships among analyses: not a surprising result from analyses that assume that gene tree heterogeneity results from incomplete lineage sorting and not gene flow. Importantly, we also observed that the confidence intervals for node ages in the coalescent analyses were quite wide, and likely susceptible to influence of the prior on node density (e.g. birth-death).

Non-native fish in aquaculture and sport fishing in Brazil: economic benefits versus risks to fish diversity in the upper River Paraná Basin

Brazil has a highly diverse freshwater fish fauna and their freshwaters provide valuable provisioning ecosystem services in aquaculture and sport angling, especially in the developed regions in the south. Non-native fish now comprise a substantial proportion of the total aquaculture production and value, contributing at least $US 250 million in 2008 (63% of the total value of freshwater fish aquaculture) according to the Fish and Agriculture Organisation. Much of this aquaculture activity is centred in Central and Southern Brazil, such as impounded sections of the upper River Parana. The non-native fishes used tend to feed at relatively low trophic levels, with the most prominently species being Cyprinus carpio and Oreochromis niloticus. Ecological risk assessment suggests these species are potentially highly invasive and deleterious to the native fish diversity of invaded water bodies. Fishes introduced for the creation of sport fisheries tend feed higher trophic levels through piscivory, such as the peacock basses (Cichla species) from Amazonia. Their introductions have generally resulted in establishment and invasion, which tends to be followed by significant and rapid declines in native fish diversity as a consequence of increased predation pressure. Thus, whilst non-native fish in the upper Parana River support provisioning ecosystem services of substantial economic value, the principal species used represent high risks to fish diversity and conservation. It is recommended local management should concentrate on reducing these risks through use of more appropriate species in these ecosystem services, with these decisions derived using risk assessment and precautionary principles.

Simultaneous delimitation of species and quantification of interspecific hybridization in Amazonian peacock cichlids (genus cichla) using multi-locus data

BackgroundIntrogression likely plays a significant role in evolution, but understanding the extent and consequences of this process requires a clear identification of species boundaries in each focal group. The delimitation of species, however, is a contentious endeavor. This is true not only because of the inadequacy of current tools to identify species lineages, but also because of the inherent ambiguity between natural populations and species paradigms. The result has been a debate about the supremacy of various species concepts and criteria. Here, we utilized multiple separate sources of molecular data, mtDNA, nuclear sequences, and microsatellites, to delimit species under a polytypic species concept (PTSC) and estimate the frequency and genomic extent of introgression in a Neotropical genus of cichlid fishes (Cichla). We compared our inferences of species boundaries and introgression under this paradigm to those when species are identified under a diagnostic species concept (DSC).ResultsWe find that, based on extensive molecular data and an inclusive species concept, 8 separate biological entities should be recognized rather than the 15 described species of Cichla. Under the PTSC, fewer individuals are expected to exhibit hybrid ancestry than under the DSC (~2% vs. ~12%), but a similar number of the species exhibit introgression from at least one other species (75% vs. 60%). Under either species concept, the phylogenetic breadth of introgression in this group is notable, with both sister species and species from different major mtDNA clades exhibiting introgression.ConclusionsIntrogression was observed to be a widespread phenomenon for delimited species in this group. While several instances of introgressive hybridization were observed in anthropogenically altered habitats, most were found in undisturbed natural habitats, suggesting that introgression is a natural but ephemeral part of the evolution of many tropical species. Nevertheless, even transient introgression may facilitate an increase in genetic diversity or transfer of adaptive mutations that have important consequences in the evolution of tropical biodiversity.

Spar genetic analysis of two invasive species of Cichla (Tucunaré) (Perciformes: Cichlidae) in the Paraná river basin

The introduction of exotic species in lake ecosystems has been greatly highlighted in the literature worldwide. Since introduction may threaten diversity of native fish, the issue turns up to be of paramount importance. Ecological effects may be predation, competition, parasitism or genetic, that is, changes in the genetic pool of populations owing to the occurrence of hybrids. Although the Tucunare fish (Cichla) is native to the Amazon region, it can be found in other hydrographic basins in which it has been introduced. RAPD molecular marker research showed that there are two species (Cichla kelberi and C. piquiti) belonging to the genus Cichla in the rivers of the Parana basin. Different morphotypes in the region may also be due to hybridization. Current research used SPAR molecular markers to confirm the presence of hybrids and the rupture of isolation mechanisms. Seventy-two specimens collected in several sites of the river Parana and Amazon basins were analyzed. Since exclusive SPAR molecular markers were obtained for Cichla kelberi and C. piquiti populations, the introduction of the two species in the region has been confirmed. Identification of the markers in specimens of the Parana river basin confirmed hybridization between these exotic species.

Growth and mortality of Cichla spp. (Perciformes, Cichlidae) introduced in Volta Grande Reservoir (Grande River) and in a small artificial lake in Southeastern Brazil

The growth and mortality parameters were estimated through the analysis of length frequency distribution for species of Cichla spp. introduced into a lake in Leme (SP), and in Volta Grande reservoir (SP-MG). In Leme, Cichla kelberi presented larger frequency in the inferior classes of lengths, larger instantaneous rate of natural mortality, and smaller number of cohorts than C. kelberi and C. piquiti in Volta Grande. The values of growth performance obtained for the species were similar, corroborating the validity of the estimated growth and mortality parameters. The increase of the growth rate in small and less diverse environments occurs due to predation. The genus Cichla adapts well in locations in which it is introduced, however this adaptation shows itself to be strongly adjusted to each particular location, determining great plasticity and establishment capacity.

Gill ectoparasite assemblages of two non-native Cichla populations (Perciformes, Cichlidae) in Brazilian reservoirs

The gills of 41 Cichla piquiti and 39 C. kelberi from Itaipu and Lajes reservoirs, respectively, Brazil, were examined to describe the ectoparasite assemblages of these two non-native peacock-bass populations. All ectoparasite species of the two studied hosts (C. piquiti and C. kelberi) were dominant, but Ascocotyle sp. (metacercariae) was the prevalent (58.53%) and most abundant helminth species in C. piquiti hosts, while Sciadicleithrum ergensi was the dominant species in C. kelberi hosts. Gill ectoparasites of C. piquiti and C. kelberi showed a typical pattern of overdispersion or aggregation, which is commonly reported for many other freshwater fishes. Ectoparasite prevalence and abundance did not vary between host sexes of the two Cichla populations. The prevalence and abundance of Ascocotyle sp. were positively correlated with C. piquiti standard length (SL), but only the abundance of S. ergensi showed a positive correlation with C. kelberi SL. Although environmental differences between reservoirs might also have influenced the results, we anticipated that the presence of a close congener in Itaipu reservoir and the lack of other Cichla species in Lajes reservoir were the key factors to explain the contrasts between C. piquiti and C. kelberi gill ectoparasites. Overall, our results suggest that the trend of parasite species loss through the invasion process may have contributed to the establishment of non-native C. piquiti and C. kelberi populations in Brazilian reservoirs.

Diet, reproduction and population structure of the introduced Amazonian fish Cichla piquiti (Perciformes: Cichlidae) in the Cachoeira Dourada reservoir (Paranaíba River, central Brazil)

The Blue Peacock Bass (Cichla piquiti), native to the Tocantins-Araguaia river basin of the Amazon system, was introduced into the basin of the Paranaíba River, Paraná River system. Cachoeira Dourada reservoir is one of a series of dams on the Paranaíba River in central Brazil, where this fish has become established. A study of its feeding spectrum, combined with information about its reproductive characteristics and population structure, would enable the current state of this species in the reservoir to be assessed and might provide useful data for the management of other species native to this habitat. This study showed that the peacock bass has no predators or natural competitors in the reservoir and that reproduces continuously, with high reproductive rates, and has a smaller median length at first maturity (L50) than other species of Cichla. Its successful establishment in habitats strongly affected by human activity should cause changes in the whole structure of the local fish communities. Nonetheless, in this reservoir, there appears to be some sharing of the functions of this species with native carnivorous fish, a situation that may be sustained by the presence of a wide variety of foraging fish.

The Casiquiare river acts as a corridor between the Amazonas and Orinoco river basins: biogeographic analysis of the genus Cichla

The Casiquiare River is a unique biogeographic corridor between the Orinoco and Amazonas basins. We investigated the importance of this connection for Neotropical fishes using peacock cichlids (Cichla spp.) as a model system. We tested whether the Casiquiare provides a conduit for gene flow between contemporary populations, and investigated the origin of biogeographic distributions that span the Casiquiare. Using sequences from the mitochondrial control region of three focal species (C. temensis, C. monoculus, and C. orinocensis) whose distributions include the Amazonas, Orinoco, and Casiquiare, we constructed maximum likelihood phylograms of haplotypes and analyzed the populations under an isolation-with-migration coalescent model. Our analyses suggest that populations of all three species have experienced some degree of gene flow via the Casiquiare. We also generated a mitochondrial genealogy of all Cichla species using >2000 bp and performed a dispersal-vicariance analysis (DIVA) to reconstruct the historical biogeography of the genus. This analysis, when combined with the intraspecific results, supports two instances of dispersal from the Amazonas to the Orinoco. Thus, our results support the idea that the Casiquiare connection is important across temporal scales, facilitating both gene flow and the dispersal and range expansion of species.

Genetic characterization of native and introduced populations of the neotropical cichlid genus Cichla in Brazil

A molecular phylogenetic analysis based on mitochondrial 16S ribosomal DNA and Control Region sequences from native and introduced populations was undertaken, in order to characterize the introduction of Cichla (peacock bass or tucunaré) species in Brazil. Mitochondrial DNA haplotypes found in introduced fish from Minas Gerais state (southeastern Brazil) clustered only with those from native species of the Tocantins River (Cichla piquiti and C. kelberi), thereby suggesting a single or, at most, few translocation acts in this area, even though with fish from the same source-population. Our study contributes to an understanding of the introduction of Cichla in regions of Brazil outside the Amazon basin, and adds phylogenetic data to the recently describe Cichla species, endemic from the Tocantins-Araguaia basin.

Microsatellite markers for the Amazon peacock bass (Cichla piquiti)

A set of primers to amplify 10 microsatellite DNA loci was developed for the Neotropical fish Cichla piquiti, one of the largest sized cichlids in the Amazon Basin. These loci were used to genotype individuals from two populations, one native population from the Tocantins River, the other an introduced population in southeast Brazil, Upper Paraná River. Cross-amplification was also successful for another species of peacock bass, C. kelberi. An average of 4.4 alleles per locus (2-9 alleles) was detected. These markers will be useful for the characterization of genetic structure of native populations, and also for invasive biology studies since Cichla species have been introduced in many river basins outside their native ranges.

Differences in reproductive seasonality of the Central American cichlidCichlasoma urophthalmusfrom three ‘cenotes’ (sinkholes)

Summary A total of 966 cichlids, Cichlasoma urophthalmus, was sampled from three karstic water bodies (cenotes) in the Yucatan Peninsula. Sex ratio was not different from 1. Specimens with ripe eggs were found during the dry and rainy seasons in the inland cenote and during the dry, rainy, and north winds seasons in the two wetland cenotes. With respect to relative fecundity, data show the C. urophthalmus inland population as two- to three-fold greater (53.1 ± 27.7) than the wetland populations (15.7 ± 5.1 and 18.2 ± 3.1). This is attributable to the different breeding strategies of C. urophthalmus populations inhabiting these two types of cenotes. In particular, the ichthyofauna from the two wetlands showed not only higher species richness (17 and 16 species) but also a higher number of potential predators (nine and eight species) as compared to the inland cenote (six species; two potential predators). It is hypothesized that C. urophthalmus adjusts its clutch size and extends its breeding periods as a response to riskier sites as compared to more secure ones; a higher competition for breeding sites and to increased fishing mortality.

Systematics, biogeography, and evolution of the Neotropical peacock basses Cichla (Perciformes: Cichlidae)

To investigate forces influencing diversification in Neotropical fishes, the phylogenetic relationships among species and populations of the cichlid genus Cichla were examined. Mitochondrial DNA was sequenced for 454 individuals of the 5 nominal Cichla species and several putative undescribed species. Phylogenetic analyses support the distinction of two major clades of Cichla. Clade A includes C. temensis and two undescribed species from the lower Amazonas and Xingu Rivers. Clade B includes C. orinocensis, C. monoculus, C. ocellaris. C, intermedia, and an undescribed species from the upper Madeira River. Species boundaries were relatively well-circumscribed for clade B, while incomplete lineage sorting was inferred for clade A. Three probable instances of introgression were observed, including a regional population of C. orinocensis from the Negro River that shows a history of introgression. Biogeographic patterns from Cichla are partially congruent with those seen in several other Neotropical fish clades, and the diversification of Cichla species is inferred to result from both vicariance and sympatric divergence.

Genetic diversity of invasive and native Cichla (Pisces: Perciformes) populations in Brazil with evidence of interspecific hybridization

Invasive and native populations of the Amazonian fishes ‘peacock bass’Cichla monoculus and of a not yet described species ‘blue tucunaré’ here referred as Cichla sp. ‘Azul’ were analysed for genetic diversity using the hypervariable domain of the mitochondrial DNA (mtDNA) control region plus steady diagnostic random amplified polymorphic DNA loci. There is no detailed historical record of the introduction of Cichla species into the Upper Paraná River basin, where they became invasive and a potential threat to local ichthyofauna. Genetic diversity among invasive populations confirmed the hypothesis of multiple introductions in this hydrographic basin. Moreover, a large and previously unknown population of natural fertile hybrids between C. cf. monoculus and Cichla sp. ‘Azul’ was identified in the Itaipu hydroelectric reservoir and in the floodplain of the Upper Paraná River. Crossbred morphotypes were similar to C. cf. monoculus, but their morphological identification was not unequivocal. This hybrid population was characterized by high genetic diversity and it was composed of hybrids possessing concurrently nuclear DNA fragments specific for C. cf. monoculus as well as fragments specific for Cichla sp. ‘Azul’. The nuclear DNA markers indicated that reproductive isolation between C. cf. monoculus and Cichla sp. ‘Azul’ has broken down in the new environment, and mtDNA sequences revealed that both species can be the female donor in the interspecific crosses. The data presented herein are potentially useful for future taxonomic, genetic and evolutionary studies in the complex Cichla group, for monitoring of invasive populations, and for further development of ecological guidelines.