scholarly journals Rapid ecological specialization despite constant population sizes

2018 ◽  
Author(s):  
Andrinajoro R Rakotoarivelo ◽  
Paul O'Donoghue ◽  
Michael W Bruford ◽  
Yoshan Moodley
Keyword(s):  
East Africa ◽  
Nuclear Dna ◽  
Incomplete Lineage Sorting ◽  
Demographic History ◽  
Secondary Contact ◽  
12S Rrna ◽  
Surprising Result ◽  
Ecological Specialization ◽  
Data Set ◽  
North East

Background. The bushbuck, Tragelaphus scriptus, is the most widespread and ecologically diverse ungulate species complex within the spiral-horned antelopes. This species was recently found to consist of two genetically divergent but monophyletic Scriptus and Sylvaticus lineages, which are paraphyletic at mitochondrial (mt)DNA owing to an ancient interspecific hybridization event. The Scriptus lineage inhabits the north-western half of the African continent while Sylvaticus is found in the south-eastern half. Here we test hypotheses of historical demography and adaptation in bushbuck using a higher-resolution framework, with four nuclear (MGF, PRKCI, SPTBN, and THY) and three new mitochondrial markers (cytochrome b, 12S rRNA, and 16S rRNA). Methods. Genealogies were reconstructed for the mitochondrial and nuclear data sets, with the latter dated using fossil calibration points. We also inferred the demographic history of Scriptus and Sylvaticus using coalescent-based methods. To obtain an overview of the origins and ancestral colonisation routes of ancestral bushbuck sequences across geographic space, we conducted a discrete Bayesian phylogeographic analysis on our nuclear DNA data set. Results. Both nDNA and mtDNA support previously findings of two genetically divergent Sylvaticus and Scriptus lineages, with no allele sharing despite coming into secondary contact at several geographic locations. The three mtDNA loci confirmed 15 of the previously defined ecotypes, including those with convergent phenotypes. However, the nuclear tree showed less phylogenetic resolution at the more derived parts of the genealogy, possibly due to incomplete lineage sorting of the slower evolving nuclear genome. The only exception to this was the montane ecotype meneliki (Sylvaticus) of the Ethiopian highlands, which formed a monophyletic group at three of four nDNA loci. We dated the coalescence of the two lineages to a common ancestor ∼2.54 million years ago. Both marker sets revealed similar demographic histories of constant population size over time. We show that the bushbuck likely originated in North-East Africa, with Scriptus colonising suitable habitats towards west of the rift and Sylvaticus diffusing from east of the rift into southern Africa. Discussion. Despite lower levels of genetic structure at nuclear loci, we confirmed the independent evolution of the Menelik’s bushbuck relative to the phenotypically similar montane ecotypes in East Africa, adding further weight to previous suggestions of convergent evolution within the bushbuck complex. Perhaps the most surprising result of our analysis was that both Scriptus and Sylvaticus populations remained relatively constant throughout the Pleistocene, which is remarkable given that this was a period of major climatic and tectonic change in Africa, and responsible for driving the evolution of much of the continents extant large mammal diversity.

scholarly journals Rapid ecological specialization despite constant population sizes

2018 ◽  
Author(s):  
Andrinajoro R Rakotoarivelo ◽  
Paul O'Donoghue ◽  
Michael W Bruford ◽  
Yoshan Moodley
Keyword(s):  
East Africa ◽  
Nuclear Dna ◽  
Incomplete Lineage Sorting ◽  
Demographic History ◽  
Secondary Contact ◽  
12S Rrna ◽  
Surprising Result ◽  
Ecological Specialization ◽  
Data Set ◽  
North East

Background. The bushbuck, Tragelaphus scriptus, is the most widespread and ecologically diverse ungulate species complex within the spiral-horned antelopes. This species was recently found to consist of two genetically divergent but monophyletic Scriptus and Sylvaticus lineages, which are paraphyletic at mitochondrial (mt)DNA owing to an ancient interspecific hybridization event. The Scriptus lineage inhabits the north-western half of the African continent while Sylvaticus is found in the south-eastern half. Here we test hypotheses of historical demography and adaptation in bushbuck using a higher-resolution framework, with four nuclear (MGF, PRKCI, SPTBN, and THY) and three new mitochondrial markers (cytochrome b, 12S rRNA, and 16S rRNA). Methods. Genealogies were reconstructed for the mitochondrial and nuclear data sets, with the latter dated using fossil calibration points. We also inferred the demographic history of Scriptus and Sylvaticus using coalescent-based methods. To obtain an overview of the origins and ancestral colonisation routes of ancestral bushbuck sequences across geographic space, we conducted a discrete Bayesian phylogeographic analysis on our nuclear DNA data set. Results. Both nDNA and mtDNA support previously findings of two genetically divergent Sylvaticus and Scriptus lineages, with no allele sharing despite coming into secondary contact at several geographic locations. The three mtDNA loci confirmed 15 of the previously defined ecotypes, including those with convergent phenotypes. However, the nuclear tree showed less phylogenetic resolution at the more derived parts of the genealogy, possibly due to incomplete lineage sorting of the slower evolving nuclear genome. The only exception to this was the montane ecotype meneliki (Sylvaticus) of the Ethiopian highlands, which formed a monophyletic group at three of four nDNA loci. We dated the coalescence of the two lineages to a common ancestor ∼2.54 million years ago. Both marker sets revealed similar demographic histories of constant population size over time. We show that the bushbuck likely originated in North-East Africa, with Scriptus colonising suitable habitats towards west of the rift and Sylvaticus diffusing from east of the rift into southern Africa. Discussion. Despite lower levels of genetic structure at nuclear loci, we confirmed the independent evolution of the Menelik’s bushbuck relative to the phenotypically similar montane ecotypes in East Africa, adding further weight to previous suggestions of convergent evolution within the bushbuck complex. Perhaps the most surprising result of our analysis was that both Scriptus and Sylvaticus populations remained relatively constant throughout the Pleistocene, which is remarkable given that this was a period of major climatic and tectonic change in Africa, and responsible for driving the evolution of much of the continents extant large mammal diversity.

scholarly journals Rapid ecological specialization despite constant population sizes

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6476 ◽  
Author(s):  
Andrinajoro R. Rakotoarivelo ◽  
Paul O’Donoghue ◽  
Michael W. Bruford ◽  
Yoshan Moodley
Keyword(s):  
East Africa ◽  
Nuclear Dna ◽  
Incomplete Lineage Sorting ◽  
Demographic History ◽  
12S Rrna ◽  
Surprising Result ◽  
Ecological Specialization ◽  
Lineage Sorting ◽  
Mt Dna ◽  
Data Set

Background The bushbuck, Tragelaphus scriptus, is a widespread and ecologically diverse ungulate species complex within the spiral-horned antelopes. This species was recently found to consist of two genetically divergent but monophyletic lineages, which are paraphyletic at mitochondrial (mt)DNA owing to an ancient interspecific hybridization event. The Scriptus lineage (T. s. scriptus) inhabits the north-western half of the African continent while Sylvaticus (T. s. sylvaticus) is found in the south-eastern half. Here we test hypotheses of historical demography and adaptation in bushbuck using a higher-resolution framework, with four nuclear (MGF, PRKCI, SPTBN, and THY) and three new mitochondrial markers (cytochrome b, 12S rRNA, and 16S rRNA). Methods Genealogies were reconstructed for the mitochondrial and nuclear data sets, with the latter dated using fossil calibration points. We also inferred the demographic history of Scriptus and Sylvaticus using coalescent-based methods. To obtain an overview of the origins and ancestral colonisation routes of ancestral bushbuck sequences across geographic space, we conducted discrete Bayesian phylogeographic and statistical dispersal-vicariance analyses on our nuclear DNA data set. Results Both nuclear DNA and mtDNA support previous findings of two genetically divergent Sylvaticus and Scriptus lineages. The three mtDNA loci confirmed 15 of the previously defined haplogroups, including those with convergent phenotypes. However, the nuclear tree showed less phylogenetic resolution at the more derived parts of the genealogy, possibly due to incomplete lineage sorting of the slower evolving nuclear genome. The only exception to this was the montane Menelik’s bushbuck (Sylvaticus) of the Ethiopian highlands, which formed a monophyletic group at three of four nuclear DNA loci. We dated the coalescence of the two lineages to a common ancestor ∼2.54 million years ago. Both marker sets revealed similar demographic histories of constant population size over time. We show that the bushbuck likely originated in East Africa, with Scriptus dispersing to colonise suitable habitats west of the African Rift and Sylvaticus radiating from east of the Rift into southern Africa via a series of mainly vicariance events. Discussion Despite lower levels of genetic structure at nuclear loci, we confirmed the independent evolution of the Menelik’s bushbuck relative to the phenotypically similar montane bushbuck in East Africa, adding further weight to previous suggestions of convergent evolution within the bushbuck complex. Perhaps the most surprising result of our analysis was that both Scriptus and Sylvaticus populations remained relatively constant throughout the Pleistocene, which is remarkable given that this was a period of major climatic and tectonic change in Africa, and responsible for driving the evolution of much of the continent’s extant large mammalian diversity.

scholarly journals Rapid ecological specialization despite constant population sizes

2018 ◽  
Author(s):  
Andrinajoro R Rakotoarivelo ◽  
Yoshan Moodley
Keyword(s):  
Incomplete Lineage Sorting ◽  
Molecular Dating ◽  
Sub Saharan Africa ◽  
Dna Polymorphisms ◽  
Secondary Contact ◽  
12S Rrna ◽  
Ecological Specialization ◽  
Lineage Sorting ◽  
Mt Dna ◽  
Data Set

Background. The bushbuck, Tragelaphus scriptus, is the most widespread and ecologically diverse ungulate species complex within the spiral-horned antelopes, occurring in approximately 73% of the total land area of sub-Saharan Africa. This species was found to consist of two genetically divergent lineages based on the mitochondrial (mt)DNA control region. One lineage inhabited the north-western half of the African continent (T. scriptus) while the other lineage (T. sylvaticus) was found in the south-eastern half. The complex was also found to comprise an unprecedented example of 23 phylogenetically distinct groups (‘ecotypes’), with montane and desert phenotypes potentially resulting from convergent evolution. The current study aim to test hypotheses regarding historical demography and adaptation of bushbuck using a higher-resolution framework, with faster evolving nuclear markers(MGF, PRKCI, SPTBN, and THY) as well as three further mitochondrial markers (cytochrome b, 12S rRNA, and 16S rRNA). Methods. Genealogies were reconstructed for the nuclear and mitochondrial data sets and for each gene independently to test the non-monphyly of the bushbuck complexe in a multi loci framework. In addition, we reconstruct the phylogeographic history of the bushbuck complex by a Bayesian discrete phylogeographic approach of our nucDNA data set to investigate its geographic diffusion and ancestral sequence location. Results. We uncovered two evolutionarily divergent lineages and geographically restricted lineages (Sylvaticus and Scriptus) of bushbuck using phylogenetics. Molecular dating indicates that these lineages last shared a common ancestor ∼2.54 million years ago. Summary statistics and analysis of the frequency distributions of DNA polymorphisms do not have any support for expanding population. Both BSPs and EBSPs indicate that the Scriptus and Sylvaticus lineages have remained relatively stable during the last 225-450Kya. Discussion. Both nucDNA and mtDNA support previously findings of two genetically divergent Sylvaticus and Scriptus lineages, despite them coming into secondary contact in several geographic regions. The three mtDNA loci confirmed 15 of the previously defined ecotypes, including those with convergent phenotypes. However, the nuclear tree showed less phylogenetic resolution at the more derived parts of the genealogy, possibly due to incomplete lineage sorting of the slower evolving nuclear genome. The only exception to this was the montane ecotype meneliki of the Ethiopian highlands, which formed a monophyletic group at three of the four nucDNA loci. The independent evolution of this group relative to phenotypically similar montane ecotypes in Africa confirm previously suggestions of convergence within the bushbuck complex.

scholarly journals Interspecific Gene Flow and the Evolution of Specialization in Black and White Rhinoceros

2020 ◽  
Vol 37 (11) ◽  
pp. 3105-3117 ◽  
Author(s):  
Yoshan Moodley ◽  
Michael V Westbury ◽  
Isa-Rita M Russo ◽  
Shyam Gopalakrishnan ◽  
Andrinajoro Rakotoarivelo ◽  
...  
Keyword(s):  
Gene Flow ◽  
De Novo ◽  
Incomplete Lineage Sorting ◽  
Early Pleistocene ◽  
Secondary Contact ◽  
Feeding Strategies ◽  
Ecological Specialization ◽  
Ancestral Gene ◽  
Black And White ◽  
White Rhinoceros

Abstract Africa’s black (Diceros bicornis) and white (Ceratotherium simum) rhinoceros are closely related sister-taxa that evolved highly divergent obligate browsing and grazing feeding strategies. Although their precursor species Diceros praecox and Ceratotherium mauritanicum appear in the fossil record ∼5.2 Ma, by 4 Ma both were still mixed feeders, and were even spatiotemporally sympatric at several Pliocene sites in what is today Africa’s Rift Valley. Here, we ask whether or not D. praecox and C. mauritanicum were reproductively isolated when they came into Pliocene secondary contact. We sequenced and de novo assembled the first annotated black rhinoceros reference genome and compared it with available genomes of other black and white rhinoceros. We show that ancestral gene flow between D. praecox and C. mauritanicum ceased sometime between 3.3 and 4.1 Ma, despite conventional methods for the detection of gene flow from whole genome data returning false positive signatures of recent interspecific migration due to incomplete lineage sorting. We propose that ongoing Pliocene genetic exchange, for up to 2 My after initial divergence, could have potentially hindered the development of obligate feeding strategies until both species were fully reproductively isolated, but that the more severe and shifting paleoclimate of the early Pleistocene was likely the ultimate driver of ecological specialization in African rhinoceros.

Phylogeny and evolution of the green lizards, Lacerta spp. (Squamata: Lacertidae) based on mitochondrial and nuclear DNA sequences

2005 ◽  
Vol 26 (3) ◽  
pp. 271-285 ◽  
Author(s):  
D. James Harris ◽  
Nuno Ferrand ◽  
Eduardo Crespo ◽  
Raquel Godinho
Keyword(s):  
Dna Sequences ◽  
Phylogenetic Relationships ◽  
Nuclear Dna ◽  
Incomplete Lineage Sorting ◽  
Bird Species ◽  
Rrna Genes ◽  
12S Rrna ◽  
Lineage Sorting ◽  
Extant Species ◽  
Mitochondrial Cytochrome B

AbstractPartial DNA sequences from three mitochondrial (cytochrome b, 12S rRNA and 16S rRNA) and two nuclear (β-fibrinogen intron 7 and C-mos) genes were used to estimate the phylogenetic relationships among all eight extant species of green lizards, Lacerta sensu stricto, and many currently recognized subspecies. All eight species form a monophyletic group. L. agilis, L. schreiberi and L. strigata are genetically well differentiated species. L. trilineata and L. pamphylica are not monophyletic units based on analyses of the β-fibrinogen intron 7. Lacerta media is closely related to some Lacerta trilineata. L. bilineata and L. viridis are closely related, and recognition of L. bilineata as a distinct species makes L. viridis paraphyletic also. For both L. bilineata and L. viridis, some subspecies appear to remain in their southern glacial refugia, while a single genetic entity shows successfully postglacial expansion. The topology derived from C-mos variation is concordant with that derived from mtDNA, with substitutions occurring at a similar rate to that of transversions in the rRNA genes. Although C-mos is typically used at deeper taxonomic levels it is also phylogenetically informative within green lizards. β-fibrinogen intron 7, typically used for assessing phylogenetic relationships among bird species, is a useful phylogenetic marker for reptiles also, showing considerable variation between species. There is not complete concordance between estimates of relationships derived from the mtDNA and nuclear markers, probably because rapid diversification led to incomplete lineage sorting in the green lizards. Introgression could also be occuring between some species.

scholarly journals Low Nucleotide Diversity in Chimpanzees and Bonobos

Genetics ◽  
2003 ◽  
Vol 164 (4) ◽  
pp. 1511-1518 ◽  
Author(s):  
Ning Yu ◽  
Michael I Jensen-Seaman ◽  
Leona Chemnick ◽  
Judith R Kidd ◽  
Amos S Deinard ◽  
...  
Keyword(s):  
Nucleotide Diversity ◽  
Nuclear Dna ◽  
Demographic History ◽  
Nuclear Genome ◽  
Limited Data ◽  
Effective Population ◽  
East Central ◽  
Dna Diversity ◽  
History Of ◽  
Mtdna Diversity

Abstract Comparison of the levels of nucleotide diversity in humans and apes may provide much insight into the mechanisms of maintenance of DNA polymorphism and the demographic history of these organisms. In the past, abundant mitochondrial DNA (mtDNA) polymorphism data indicated that nucleotide diversity (π) is more than threefold higher in chimpanzees than in humans. Furthermore, it has recently been claimed, on the basis of limited data, that this is also true for nuclear DNA. In this study we sequenced 50 noncoding, nonrepetitive DNA segments randomly chosen from the nuclear genome in 9 bonobos and 17 chimpanzees. Surprisingly, the π value for bonobos is only 0.078%, even somewhat lower than that (0.088%) for humans for the same 50 segments. The π values are 0.092, 0.130, and 0.082% for East, Central, and West African chimpanzees, respectively, and 0.132% for all chimpanzees. These values are similar to or at most only 1.5 times higher than that for humans. The much larger difference in mtDNA diversity than in nuclear DNA diversity between humans and chimpanzees is puzzling. We speculate that it is due mainly to a reduction in effective population size (Ne) in the human lineage after the human-chimpanzee divergence, because a reduction in Ne has a stronger effect on mtDNA diversity than on nuclear DNA diversity.

Relations Between Neighbouring States in North-East Africa

1984 ◽  
Vol 22 (2) ◽  
pp. 273-285
Author(s):  
Peter Woodward
Keyword(s):  
East Africa ◽  
International Society ◽  
International Politics ◽  
International Order ◽  
International Dimension ◽  
North East ◽  
Pan Africanism ◽  
Foreign Politics ◽  
New States ◽  
Domestic Affairs

In recent years there has been a resurgence of interest in international politics in Africa. After the initial post-independence discussion of pan-Africanism the international dimension seemed overshadowed by the concern to account for domestic developments in many new states, and it is this imbalance which is now being redressed. Indeed, it has recently been argued by Robert Jackson and Carl Rosberg that, contrary to the situation elsewhere, Africa's international politics have assumed an order which is sadly lacking in the domestic affairs of many states: ‘At the level of international society, a framework of rules and conventions governing the relations of the states in the region has been bounded and sustained for almost two decades.’ If the contrast between internal anarchy and international order seems somewhat exaggerated, the distinction between domestic and foreign politics appears both conventional and appropriate.

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