Adaptive radiation of Lake Tana's (Ethiopia) Labeobarbus species flock (Pisces, Cyprinidae)

2008 ◽  
Vol 59 (5) ◽  
pp. 391 ◽  
Author(s):  
Martin de Graaf ◽  
Eshete Dejen ◽  
Jan W. M. Osse ◽  
Ferdinand A. Sibbing
Keyword(s):  
Prey Species ◽  
Prey Size ◽  
Species Flock ◽  
East African ◽  
Lake Tana ◽  
Ecological Diversification ◽  
Ecological Selection ◽  
Cyprinid Fishes ◽  
Temporal Dimensions ◽  
Species Flocks

Studying species flocks (e.g. Darwin’s finches, Caribbean anoline lizards, East African cichlid fishes) has proven to be highly successful in understanding the forces driving speciation. The only known, intact species flock of cyprinid fishes, the 15 Labeobarbus species in Lake Tana (Ethiopia), includes eight piscivorous species. Piscivory is a rare specialisation among the highly successful (>2000 species) but mostly benthivorous Cyprinidae. The extent and mechanisms of diversification of this remarkable Labeobarbus species flock, particularly among the unexpected piscivorous species, are still largely unknown. In the present study we demonstrate that all 15 Labeobarbus species are segregated to a great extent along spatial, trophic and/or temporal dimensions. The spatial distribution, diet (prey species but not prey size), time of active feeding and predation techniques differed significantly among the eight piscivores. Lake Tana’s cyprinids displayed their retained potential for ecological diversification and speciation, including the uncommon specialisation of piscivory. The latter is probably a result of the absence of common African specialist piscivores in Lake Tana. We suggest that the evolution of Lake Tana’s Labeobarbus species flock at this stage is predominantly structured by ecological selection models. The labeobarbs most likely underwent sequential stages of radiation and speciation: habitat divergence followed by trophic divergence.

scholarly journals On the origin of the Synodontis catfish species flock from Lake Tanganyika

2006 ◽  
Vol 2 (4) ◽  
pp. 548-552 ◽  
Author(s):  
Julia J Day ◽  
Mark Wilkinson
Keyword(s):  
Lake Tanganyika ◽  
Sequence Data ◽  
Phylogenetic Study ◽  
Species Flock ◽  
East African ◽  
Extrinsic Factors ◽  
Factors Affecting ◽  
Fossil Calibration ◽  
Mtdna Sequence ◽  
Species Flocks

Species flocks within Great Lakes provide unique insights into the factors affecting diversification. Lake Tanganyika (LT) is of particular interest because it contains many endemic groups for which general factors affecting diversification can be discerned. Here, we present the first phylogenetic study of the LT Synodontis (Siluriformes, Mochokidae) species flock using mtDNA sequence data. Our data reveal some previously unrecognized species diversity and indicate that the LT species flock is not monophyletic, and that two closely related clades of endemics may have independently colonized LT. Other comparable small species flocks are characterized by a single colonization event. Molecular date estimates of the timing of the initial within-lake diversification of the LT endemics, based on a fossil calibration, are comparable to those reported for other groups, suggesting that extrinsic factors maybe important common causes of clade diversification. The basal divergence in the sampled Synodontis reveals an East–West African faunal split seen in many terrestrial, but few aquatic groups, the timing of which coincides with East African rifting events.

Experimental evidence for the biological species status in Lake Tana's Labeobarbus flock (Cyprinidae)

2010 ◽  
Vol 60 (2) ◽  
pp. 183-193 ◽  
Author(s):  
Arjan Palstra ◽  
Martin de Graaf ◽  
Leo Nagelkerke ◽  
Ferdinand Sibbing
Keyword(s):  
Genetic Basis ◽  
Direct Proof ◽  
Morphological Differentiation ◽  
Common Garden ◽  
Biological Species ◽  
Species Flock ◽  
Lake Tana ◽  
Cyprinid Fishes ◽  
Morphological Differences ◽  
Common Garden Experiments

AbstractLake Tana (Ethiopia) harbours the only known remaining intact species flock of large (max. 100 cm standard length, SL) cyprinid fishes (15 Labeobarbus spp.). In 'common garden' experiments progeny of the riverine spawning benthivorous L. tsanensis, and of the piscivorous L. truttiformis and L. megastoma was raised under similar environmental conditions to test if interspecific morphological differentiation would occur. Interspecific morphological differences and divergence were clearly observed early in ontogeny (≤ 40 mm SL). This study is the first to demonstrate direct proof for the genetic basis of morphological differentiation among these labeobarbs, providing further support that Lake Tana's labeobarb species are true biological species.

Evolutionary origin of Lake Tana's (Ethiopia) small Barbus species: indications of rapid ecological divergence and speciation

2007 ◽  
Vol 57 (1) ◽  
pp. 39-48 ◽  
Author(s):  
Johannis Samallo ◽  
Hendrik-Jan Megens ◽  
Martin De Graaf ◽  
Ferdinand Sibbing
Keyword(s):  
Genetic Divergence ◽  
Species Flock ◽  
Similar Species ◽  
Lineage Sorting ◽  
Drainage Basins ◽  
Lake Tana ◽  
The North ◽  
Rivers And Lakes ◽  
Cyprinid Fishes ◽  
North Western

AbstractLake Tana, located in the north-western highlands of Ethiopia, contains a unique assemblage of cyprinid fishes. In addition to the only known intact species flock of large (max. 100 cm forklength (FL)) Labeobarbus species, the lake harbours three small (<10 cm FL) Barbus species: B. humilis Boulenger, 1902, B. pleurogramma Boulenger, 1902 and B. tanapelagius de Graaf, Dejen, Sibbing and Osse, 2000. Phylogenetic relationships of the small Barbus species of Lake Tana were investigated using the mtDNA cytochrome b gene. All small Barbus species occurring in Lake Tana are part of the 'small African diploid' groups identified by Tsigenopoulos et al. (2002). Barbus pleurogramma, only reported in Lake Tana, and populations of the morphologically similar species, B. paludinosus Peters, 1852, collected in rivers and lakes throughout Ethiopia, comprised a monophyletic group with separate clades congruent with drainage basins. Barbus pleurogramma could well be a cryptic species rather than synonymous to B. paludinosus as previously suggested. The genetic divergence between B. humilis and B. tanapelagius was very low, and without lineage sorting of haplotypes. This is probably due to recent (<16 000 years ago) evolution of the pelagic, zooplanktivorous B. tanapelagius from the benthic, omnivorous B. humilis after the formation of Lake Tana.

Context-specific behavior serves as a mechanism of interspecific cohesion in mixed-species flocks

The Auk ◽  
2021 ◽  
Author(s):  
Sean M Williams ◽  
Catherine A Lindell
Keyword(s):  
Flight Distance ◽  
Species Flock ◽  
Mixed Species ◽  
Specific Behavior ◽  
Call Type ◽  
Interspecific Associations ◽  
Mixed Species Flocks ◽  
Context Specific ◽  
Species Flocks

Abstract We investigated whether context-specific behavior is responsible for the cohesion of mixed-species flocks of antshrikes and antwrens in Amazonian Peru. Antshrikes perform a behavior while spatially repositioning, to which antwrens respond by approaching. The cohesion of interspecific associations requires communication, although the mechanisms often are unexplored. In monospecific groups, cohesion among individuals is maintained with actions or vocalizations given in a certain context. Dusky-throated Antshrikes (Thamnomanes ardesiacus) vocalize while in flight and the number of times they vocalize covaries with the flight distance. We refer to this pairing of flight and vocalization as repositioning behavior. Furthermore, antshrikes pair a different call type with perching, which we refer to as perching behavior. We followed Long-winged (Myrmotherula longipennis) and White-flanked Antwrens (M. axillaris) and recorded their response following natural vocalizations (no playback used) given by the antshrikes. Long-winged Antwrens, but not White-flanked, flew toward an antshrike significantly sooner and were more likely to approach the antshrikes after the repositioning behavior than after perching behavior. In addition, Long-winged Antwrens, but not White-flanked, flew toward an antshrike sooner after a longer series of repositioning calls than after a shorter series. We did not distinguish between the Long-winged Antwrens’ response as a function of movement vs. vocalizations of the antshrikes, although we argue that vocalizations are likely a more important communication component of repositioning behavior than movement. It remains unclear whether the antshrikes are deliberately signaling the Long-winged Antwrens or the antwrens are taking advantage of the repositioning behavior; active signaling is possible since antshrikes benefit from antwrens. White-flanked Antwrens may be less responsive to the antshrikes since they have a lower propensity to occur in a mixed-species flock. The results indicate that the repositioning behavior of Dusky-throated Antshrikes is a key mechanism of interspecific cohesion of Amazonian mixed-species flocks of the understory.

Evolution of MHC class II &; chain-encoding genes in the Lake Tana barbel species flock (Barbus intermedius complex)

1996 ◽  
Vol 44 (6) ◽  
pp. 419-431 ◽  
Author(s):  
Brian Dixon ◽  
Leo A. J. Nagelkerke ◽  
Ferdinand A. Sibbing ◽  
Egbert Egberts ◽  
René J. M. Stet
Keyword(s):  
Mhc Class Ii ◽  
Class Ii ◽  
Species Flock ◽  
Lake Tana ◽  
Encoding Genes ◽  
Barbus Intermedius

The occurrence of species flocks in the nematode genus Cloacina (Strongyloidea : Cloacininae), parasitic in the stomachs of kangaroos and wallabies

2002 ◽  
Vol 50 (6) ◽  
pp. 597 ◽  
Author(s):  
I. Beveridge ◽  
N. B. Chilton ◽  
D. M. Spratt
Keyword(s):  
Host Specificity ◽  
Host Species ◽  
Nematode Species ◽  
Morphological Data ◽  
Species Flock ◽  
Sampling Effort ◽  
Nematode Genus ◽  
Single Host ◽  
Species Flocks ◽  
Occurrence Of Species

The occurrence of species flocks within the nematode genus Cloacina was examined using the criteria of host specificity, co-occurrence and monophyly. Species of Cloacina generally exhibited a high degree of host specificity, with most species occurring either in a single host species or in two closely related host species. The frequency distribution of numbers of component species of Cloacina per host species indicated that most host species harboured 2–4 species of nematodes, with an approximately exponential decline in the number of species of parasites to a maximum of 20 species of nematode per host species. Host species harbouring eight or more species of Cloacina were found within a single recent macropodid clade, but there was no correlation between evolutionary age of the host and the number of parasite species harboured. Sampling effort was significantly correlated with the number of nematode species found and, in partial regression analysis, subsumed the effects of host body size and geographic range, which were found to be significant correlates with the number of nematode species present in preliminary analyses. Analysis of co-occurrences of nematode species indicated significant variation between host species, with some hosts (e.g. Macropus agilis) most commonly harbouring a single species of Cloacina, while closely related host species (e.g. M. dorsalis) most commonly harboured numerous species. Parsimony analysis of species of Cloacina based on morphological data suggested that while small series of related nematode species could be identified within a single host species, the species flock in each host species is polyphyletic in origin. Species flocks contributed significantly to community richness in some host species.

Discerning the diets of sweep-feeding eurypterids: assessing the importance of prey size to survivorship across the Late Devonian mass extinction in a phylogenetic context

Paleobiology ◽  
2020 ◽  
pp. 1-13
Author(s):  
Emily S. Hughes ◽  
James C. Lamsdell
Keyword(s):  
Mass Extinction ◽  
Prey Species ◽  
Size Range ◽  
Prey Size ◽  
Phylogenetic Signal ◽  
Late Devonian ◽  
Evolutionary Trend ◽  
Average Spacing ◽  
Horseshoe Crabs ◽  
Mode Of Life

Abstract Eurypterids are generally considered to comprise a mixture of active nektonic to nektobenthic predators and benthic scavenger-predators exhibiting a mode of life similar to modern horseshoe crabs. However, two groups of benthic stylonurine eurypterids, the Stylonuroidea and Mycteropoidea, independently evolved modifications to the armature of their anterior appendages that have been considered adaptations toward a sweep-feeding life habit, and it has been suggested the evolution toward sweep-feeding may have permitted stylonurines to capture smaller prey species and may have been critical for the survival of mycteropoids during the Late Devonian mass extinction. There is a linear correlation between the average spacing of feeding structures and prey sizes among extant suspension feeders. Here, we extrapolate this relationship to sweep-feeding eurypterids in order to estimate the range of prey sizes that they could capture and examine prey size in a phylogenetic context to determine what role prey size played in determining survivorship during the Late Devonian. The mycteropoid Cyrtoctenus was the most specialized sweep-feeder, with comblike appendage armature capable of capturing mesoplankton out of suspension, while the majority of stylonurines possess armature corresponding to a prey size range of 1.6–52 mm, suggesting they were suited for capturing small benthic macroinvertebrates such as crustaceans, mollusks, and wormlike organisms. There is no clear phylogenetic signal to prey size distribution and no evolutionary trend toward decreasing prey sizes among Stylonurina. Rather than prey size, species survivorship during the Late Devonian was likely mediated by geographic distribution and ability to capitalize on the expanding freshwater benthos.

Major histocompatibility genes in the Lake Tana African large barb species flock: evidence for complete partitioning of class II B, but not class I, genes among different species

2005 ◽  
Vol 56 (12) ◽  
pp. 894-908 ◽  
Author(s):  
Corine P. Kruiswijk ◽  
Trudi Hermsen ◽  
Joost van Heerwaarden ◽  
Brian Dixon ◽  
Huub F. J. Savelkoul ◽  
...  
Keyword(s):  
Class Ii ◽  
Class I ◽  
Species Flock ◽  
Major Histocompatibility ◽  
Lake Tana

scholarly journals Linkage Relationships and Haplotype Polymorphism Among Cichlid Mhc Class II B Loci

Genetics ◽  
1998 ◽  
Vol 149 (3) ◽  
pp. 1527-1537
Author(s):  
Edward Málaga-Trillo ◽  
Zofia Zaleska-Rutczynska ◽  
Brendan McAndrew ◽  
Vladimir Vincek ◽  
Felipe Figueroa ◽  
...  
Keyword(s):  
Mhc Class Ii ◽  
Adaptive Radiation ◽  
Genetic System ◽  
Class Ii ◽  
East African ◽  
Cichlid Species ◽  
Definition Of ◽  
The Individual ◽  
Haploid Embryos ◽  
Species Flocks

Abstract The species flocks of cichlid fishes in the Great East African Lakes are paradigms of adaptive radiation and hence, of great interest to evolutionary biologists. Phylogenetic studies of these fishes have, however, been hampered by the lack of suitable polymorphic markers. The genes of the major histocompatibility complex hold the promise to provide, through their extensive polymorphism, a large number of such markers, but their use has been hampered by the complexity of the genetic system and the lack of definition of the individual loci. In this study we take the first substantial step to alleviate this problem. Using a combination of methods, including the typing of single sperm cells, gyno- or androgenetic individuals, and haploid embryos, as well as sequencing of class II B restriction fragments isolated from gels for Southern blots, we identify the previously characterized homology groups as distinct loci. At least 17 polymorphic class II B loci, all of which are presumably transcribed, have been found among the different species studied. Most of these loci are shared across the various cichlid species and genera. The number of loci per haplotype varies from individual to individual, ranging from 1 to 13. A total of 21 distinct haplotypes differing in the number of loci they carry has thus far been identified. All the polymorphic loci are part of the same cluster in which, however, distances between at least some of the loci (as indicated by recombination frequencies) are relatively large. Both the individual loci and the haplotypes can now be used to study phylogenetic relationships among the members of the species flocks and the mode in which speciation occurs during adaptive radiation.

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