scholarly journals Epigenetic and genetic variation between two behaviorally isolated species of Neoconocephalus (Orthoptera: Tettigonioidea)

2019 ◽  
Vol 28 (2) ◽  
pp. 11-19
Author(s):  
Gideon Ney ◽  
Johannes Schul
Keyword(s):  
Secondary Contact ◽  
Species Differentiation ◽  
Polymorphism Analysis ◽  
Epigenetic Variation ◽  
Isolated Populations ◽  
Isolating Mechanisms ◽  
Rapid Changes ◽  
Species Groups ◽  
Epigenetic Signatures ◽  
Isolated Species

Epigenetic variation allows for rapid changes in phenotypes without alterations to nucleotide sequences. These epigenetic signatures may diverge over time among isolated populations. Epigenetic incompatibility following secondary contact between these populations could result in the evolution of reproductive isolating mechanisms. If epigenetic incompatibility drove the evolution of species isolating mechanisms, we expect to see significant epigenetic differentiation between these species. Alternatively, epigenetic variation could be the result of predominantly environmental variables and not align along species boundaries. A methylation sensitive amplified fragment length polymorphism analysis was performed on individuals of the closely related katydid species Neoconocephalusrobustus and N.bivocatus. We observed significant variation in total methylation levels between species. However, genetic differentiation remained larger than epigenetic differentiation between species groups. We measured a significant correlation between the epigenetic and genetic distance between individuals. Epigenetic differentiation is therefore likely the result of an interaction between genetic and epigenetic loci and not a mechanism for species differentiation. We therefore did not find evidence to support our hypothesis of an epigenetically mediated mechanism for speciation between N.robustus and N.bivocatus.

scholarly journals Genome assembly, structural variants, and genetic differentiation between Lake Whitefish young species pairs (Coregonus sp.) with long and short reads

2022 ◽  
Author(s):  
Claire M&eacuterot ◽  
Kristina S R Stenl&oslashkk ◽  
Clare Venney ◽  
Martin Laporte ◽  
Michel Moser ◽  
...  
Keyword(s):  
Transposable Elements ◽  
Genetic Architecture ◽  
Large Fraction ◽  
Sympatric Species ◽  
Secondary Contact ◽  
Species Differentiation ◽  
Lake Whitefish ◽  
Structural Variants ◽  
Species Pairs ◽  
Long Read

The parallel evolution of nascent pairs of ecologically differentiated species offers an opportunity to get a better glimpse at the genetic architecture of speciation. Of particular interest is our recent ability to consider a wider range of genomic variants, not only single-nucleotide polymorphisms (SNPs), thanks to long-read sequencing technology. We can now identify structural variants (SVs) like insertions, deletions, and other structural rearrangements, allowing further insights into the genetic architecture of speciation and how different variants are involved in species differentiation. Here, we investigated genomic patterns of differentiation between sympatric species pairs (Dwarf and Normal) belonging to the Lake Whitefish (Coregonus clupeaformis) species complex. We assembled the first reference genomes for both Dwarf and Normal Lake Whitefish, annotated the transposable elements, and analysed the genome in the light of related coregonid species. Next, we used a combination of long-read and short-read sequencing to characterize SVs and genotype them at population-scale using genome-graph approaches, showing that SVs cover five times more of the genome than SNPs. We then integrated both SNPs and SVs to investigate the genetic architecture of species differentiation in two different lakes and highlighted an excess of shared outliers of differentiation. In particular, a large fraction of SVs differentiating the two species was driven by transposable elements (TEs), suggesting that TE accumulation during a period of allopatry predating secondary contact may have been a key process in the speciation of the Dwarf and Normal Whitefish. Altogether, our results suggest that SVs play an important role in speciation and that by combining second and third generation sequencing we now have the ability to integrate SVs into speciation genomics.

scholarly journals A new species of the genus Canthon Hoffmannsegg (Coleoptera, Scarabaeidae, Scarabaeinae, Deltochilini) from central Brazil

2020 ◽  
Author(s):  
Fernando Z. Vaz-de-Mello ◽  
Luis Gabriel De Oliveira Albuquerque Nunes ◽  
Vinícius Da Costa-Silva
Keyword(s):  
New Species ◽  
Related Species ◽  
Taxonomic Revision ◽  
Central Brazil ◽  
Incertae Sedis ◽  
Species Groups ◽  
A New Species ◽  
Isolated Species

A new species of Canthon is described, illustrated and the morphological similarities with related species are discussed. The species Canthon cleidecostae was named after Dr. Cleide Costa a great beetles specialist. The subgeneric category of species is considered incertae sedis until the taxonomic revision of the genus Canthon is fully addressed. Also, we provide a key for genera, subgenera and isolated species-groups that can be confused with the genus Canthon.

Origin and Geography of the Fish Fauna of the Laurentian Great Lakes Basin

1981 ◽  
Vol 38 (12) ◽  
pp. 1539-1561 ◽  
Author(s):  
Reeve M. Bailey ◽  
Gerald R. Smith
Keyword(s):  
Great Lakes ◽  
Lake Trout ◽  
Lake Superior ◽  
Fish Fauna ◽  
Secondary Contact ◽  
Species Differentiation ◽  
Stizostedion Vitreum ◽  
Great Lakes Basin ◽  
Geological Evidence ◽  
The Past

The native fishes of the Great Lakes basin consist of 153 species, 64 genera, and 25 families. The total ichthyofaunal lists for the several lakes and (in parentheses) their tributary basins are as follows: Nipigon (and tributaries), 40; Superior, 53 (82); Michigan, 91 (135); Huron, 90 (112); St. Clair and Detroit River 108; Erie, 106 (125); Ontario, 95 (125). (These totals include 21 introduced species, most named species of ciscoes and chubs, and the blue pike (Stizostedion vitreum glaucum).)Several areas show notable within-species differentiation. Tributaries to Lake Ontario are part of a zone of secondary contact of a few small, nonmanaged, subspecies that entered the basin from both eastern and western glacial refugia. In the Great Lakes themselves, stocks of lake trout (Salvelinus namaycush), ciscoes, walleyes (Stizostedion vitreum vitreum), and a few nonmanaged species stem from differentiation within the basin or reflect interglacial events that occurred in Mississippi refugia.Species distribution patterns suggest colonization of the Great Lakes by 122 kinds solely from Mississippi basin refugia, 14 kinds only from Atlantic drainage refugia, and dual refugia for at least 18 kinds. Geological evidence provides some support for this interpretation. It is unlikely that any species colonized the Great Lakes from an Alaskan refuge in the past 14 000 yr.The ciscoes and chubs of the genus Coregonus include numerous genetically differentiated stocks, some of which may predate the opening of the Great Lakes in the past 14 000 yr. This conclusion is based on the occurrence in Lake Nipigon and Lake Superior of several forms that must have colonized prior to 9000 yr ago when the last access existed from Lake Superior to Lake Nipigon. At least four and perhaps up to eight forms of Great Lakes coregonines probably survived (or differentiated during) the last glaciation south of the ice in proglacial waters at the heads of major river systems. There is no evidence to support the hypothesized post-Wisconsinan dispersal of any of these forms from a northwestern refugium or their Pleistocene derivation by introgression with a Eurasian species.Despite the evidence for some long-standing genetic differentiation within Coregonus, morphological and biochemical characters fail to support the unequivocal recognition within the Great Lakes of more than one to four current biological species (apart from clupeaformis). The presently recognized species are groups of stocks whose position in the classification system is problematical. The named groups (two of which are extinct) included numerous stocks that were (or are) isolated by homing behavior specific to time and place. The lack of intrinsic reproductive isolation among forms increases their vulnerability to extinction because rare forms apparently hybridize with common forms spawning at adjacent times or places.Key words: biogeography, Coregonus, fish, Great Lakes, introduced fishes, Pleistocene, species, subspecies

scholarly journals Ultraviolet B Radiation Triggers DNA Methylation Change and Affects Foraging Behavior of the Clonal Plant Glechoma longituba

2021 ◽  
Vol 12 ◽  
Author(s):  
Jiaxin Quan ◽  
Vít Latzel ◽  
Dan Tie ◽  
Yuhan Zhang ◽  
Zuzana Münzbergová ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Foraging Behavior ◽  
Clonal Plants ◽  
Ultraviolet B ◽  
Light Environment ◽  
Polymorphism Analysis ◽  
Epigenetic Variation ◽  
Heterogeneous Environment ◽  
Distributed Resources ◽  
Glechoma Longituba

Clonal plants in heterogeneous environments can benefit from their habitat selection behavior, which enables them to utilize patchily distributed resources efficiently. It has been shown that such behavior can be strongly influenced by their memories on past environmental interactions. Epigenetic variation such as DNA methylation was proposed to be one of the mechanisms involved in the memory. Here, we explored whether the experience with Ultraviolet B (UV-B) radiation triggers epigenetic memory and affects clonal plants’ foraging behavior in an UV-B heterogeneous environment. Parental ramets of Glechoma longituba were exposed to UV-B radiation for 15 days or not (controls), and their offspring ramets were allowed to choose light environment enriched with UV-B or not (the species is monopodial and can only choose one environment). Sizes and epigenetic profiles (based on methylation-sensitive amplification polymorphism analysis) of parental and offspring plants from different environments were also analyzed. Parental ramets that have been exposed to UV-B radiation were smaller than ramets from control environment and produced less and smaller offspring ramets. Offspring ramets were placed more often into the control light environment (88.46% ramets) than to the UV-B light environment (11.54% ramets) when parental ramets were exposed to UV-B radiation, which is a manifestation of “escape strategy.” Offspring of control parental ramets show similar preference to the two light environments. Parental ramets exposed to UV-B had lower levels of overall DNA methylation and had different epigenetic profiles than control parental ramets. The methylation of UV-B-stressed parental ramets was maintained among their offspring ramets, although the epigenetic differentiation was reduced after several asexual generations. The parental experience with the UV-B radiation strongly influenced foraging behavior. The memory on the previous environmental interaction enables clonal plants to better interact with a heterogeneous environment and the memory is at least partly based on heritable epigenetic variation.

scholarly journals Sympatric speciation of wild emmer wheat driven by ecology and chromosomal rearrangements

2020 ◽  
Vol 117 (11) ◽  
pp. 5955-5963 ◽  
Author(s):  
Hongwei Wang ◽  
Huayan Yin ◽  
Chengzhi Jiao ◽  
Xiaojian Fang ◽  
Guiping Wang ◽  
...  
Keyword(s):  
Chromosomal Rearrangements ◽  
Sympatric Speciation ◽  
Wild Emmer Wheat ◽  
Emmer Wheat ◽  
Wild Emmer ◽  
Ancestral Population ◽  
Secondary Contact ◽  
Ros Scavenging ◽  
Isolated Populations ◽  
Ecological Selection

In plants, the mechanism for ecological sympatric speciation (SS) is little known. Here, after ruling out the possibility of secondary contact, we show that wild emmer wheat, at the microclimatically divergent microsite of “Evolution Canyon” (EC), Mt. Carmel, Israel, underwent triple SS. Initially, it split following a bottleneck of an ancestral population, and further diversified to three isolated populations driven by disruptive ecological selection. Remarkably, two postzygotically isolated populations (SFS1 and SFS2) sympatrically branched within an area less than 30 m at the tropical hot and dry savannoid south-facing slope (SFS). A series of homozygous chromosomal rearrangements in the SFS1 population caused hybrid sterility with the SFS2 population. We demonstrate that these two populations developed divergent adaptive mechanisms against severe abiotic stresses on the tropical SFS. The SFS2 population evolved very early flowering, while the SFS1 population alternatively evolved a direct tolerance to irradiance by improved ROS scavenging activity that potentially accounts for its evolutionary fate with unstable chromosome status. Moreover, a third prezygotically isolated sympatric population adapted on the abutting temperate, humid, cool, and forested north-facing slope (NFS), separated by 250 m from the SFS wild emmer wheat populations. The NFS population evolved multiple resistant loci to fungal diseases, including powdery mildew and stripe rust. Our study illustrates how plants sympatrically adapt and speciate under disruptive ecological selection of abiotic and biotic stresses.

scholarly journals Geographic and Ecological Dimensions of Host Plant-Associated Genetic Differentiation and Speciation in the Rhagoletis cingulata (Diptera: Tephritidae) Sibling Species Group

Insects ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 275 ◽  
Author(s):  
Doellman ◽  
Schuler ◽  
Jean ◽  
Hood ◽  
Egan ◽  
...  
Keyword(s):  
Reproductive Isolation ◽  
Sibling Species ◽  
Adaptive Radiation ◽  
Ecological Theory ◽  
Species Group ◽  
Secondary Contact ◽  
Similar Species ◽  
Isolated Populations ◽  
Ecological Diversification ◽  
Postzygotic Reproductive Isolation

Ascertaining the causes of adaptive radiation is central to understanding how new species arise and come to vary with their resources. The ecological theory posits adaptive radiation via divergent natural selection associated with novel resource use; an alternative suggests character displacement following speciation in allopatry and then secondary contact of reproductively isolated but ecologically similar species. Discriminating between hypotheses, therefore, requires the establishment of a key role for ecological diversification in initiating speciation versus a secondary role in facilitating co-existence. Here, we characterize patterns of genetic variation and postzygotic reproductive isolation for tephritid fruit flies in the Rhagoletis cingulata sibling species group to assess the significance of ecology, geography, and non-adaptive processes for their divergence. Our results support the ecological theory: no evidence for intrinsic postzygotic reproductive isolation was found between two populations of allopatric species, while nuclear-encoded microsatellites implied strong ecologically based reproductive isolation among sympatric species infesting different host plants. Analysis of mitochondrial DNA suggested, however, that cytoplasmic-related reproductive isolation may also exist between two geographically isolated populations within R cingulata. Thus, ecology associated with sympatric host shifts and cytoplasmic effects possibly associated with an endosymbiont may be the key initial drivers of the radiation of the R. cingulata group.

scholarly journals Where and when does a ring start and end? Testing the ring-species hypothesis in a species complex of Australian parrots

2008 ◽  
Vol 275 (1650) ◽  
pp. 2431-2440 ◽  
Author(s):  
Leo Joseph ◽  
Gaynor Dolman ◽  
Stephen Donnellan ◽  
Kathleen M Saint ◽  
Mathew L Berg ◽  
...  
Keyword(s):  
Population Genetics ◽  
Population Expansion ◽  
Temporal Analysis ◽  
Secondary Contact ◽  
Isolated Populations ◽  
Circular Distribution ◽  
Spatio Temporal ◽  
A Chain ◽  
Ring Species ◽  
Ring Speciation

Speciation, despite ongoing gene flow can be studied directly in nature in ring species that comprise two reproductively isolated populations connected by a chain or ring of intergrading populations. We applied three tiers of spatio-temporal analysis (phylogeny/historical biogeography, phylogeography and landscape/population genetics) to the data from mitochondrial and nuclear genomes of eastern Australian parrots of the Crimson Rosella Platycercus elegans complex to understand the history and present genetic structure of the ring they have long been considered to form. A ring speciation hypothesis does not explain the patterns we have observed in our data (e.g. multiple genetic discontinuities, discordance in genotypic and phenotypic assignments where terminal differentiates meet). However, we cannot reject that a continuous circular distribution has been involved in the group's history or indeed that one was formed through secondary contact at the ‘ring's’ east and west; however, we reject a simple ring-species hypothesis as traditionally applied, with secondary contact only at its east. We discuss alternative models involving historical allopatry of populations. We suggest that population expansion shown by population genetics parameters in one of these isolates was accompanied by geographical range expansion, secondary contact and hybridization on the eastern and western sides of the ring. Pleistocene landscape and sea-level and habitat changes then established the birds' current distributions and range disjunctions. Populations now show idiosyncratic patterns of selection and drift. We suggest that selection and drift now drive evolution in different populations within what has been considered the ring.

scholarly journals Biometrical, Biochemical, and Molecular Diagnosis of Portuguese Meloidogyne hispanica Isolates

Plant Disease ◽  
2012 ◽  
Vol 96 (6) ◽  
pp. 865-874 ◽  
Author(s):  
Carla M. Maleita ◽  
Maria José Simões ◽  
Conceição Egas ◽  
Rosane H. C. Curtis ◽  
Isabel M. de O. Abrantes
Keyword(s):  
Original Description ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Molecular Characteristics ◽  
Species Differentiation ◽  
Polymorphism Analysis ◽  
Accurate Identification ◽  
Restriction Sites ◽  
Meloidogyne Spp ◽  
Enzyme Pattern

Meloidogyne hispanica infects many economically important crops worldwide. The accurate identification of this pathogen is essential for the establishment of efficient and sustainable integrated pest management programs. Portuguese M. hispanica isolates were studied by biometrical, biochemical, and molecular characteristics. Biometrical characteristics of M. hispanica females, males, and second-stage juveniles were similar to the original description. Biochemical studies revealed a unique enzyme pattern (Hi4) for M. hispanica esterases that allowed for species differentiation. Molecular analysis of the mtDNA region from COII and 16S rRNA genes resulted in amplification products (1,800 bp) similar to M. hispanica, M. ethiopica, and M. javanica, and the described HinfI was unable to discriminate M. hispanica from the other two species. Analysis of the mtDNA sequences revealed altered nucleotides among the isolates that created new restriction sites for AluI and DraIII. The resulting restriction patterns successfully discriminated between the three species, providing a new tool for Meloidogyne identification. Finally, the phylogenetic relationship between M. hispanica and several Meloidogyne spp. sequences was analyzed using mtDNA, confirming the divergence between meiotic and mitotic species and revealing the proximity of M. hispanica to closely related species. Based on the studies conducted, the application of isozyme or polymerase chain reaction restriction fragment length polymorphism analysis would be a useful and efficient methodology for M. hispanica identification.

Wood and Bark Anatomy of Buchenavia Eichl. (Combretaceae)1

IAWA Journal ◽  
1991 ◽  
Vol 12 (2) ◽  
pp. 123-141 ◽  
Author(s):  
Veronica Angyallossy Alfonso ◽  
Hans Georg Richter
Keyword(s):  
Personal Communication ◽  
Individual Species ◽  
Species Differentiation ◽  
Diagnostic Features ◽  
Axial Parenchyma ◽  
Close Relationship ◽  
Variable Feature ◽  
Species Groups ◽  
Bark Anatomy ◽  
Bark Structure

Wood and bark structure of Buchenavia (Combretaceae) was studied for infrageneric variation and taxonomic utility. Despite its wide neotropical distribution Buchenavia has a homogeneous wood anatomy, axial parenchyma distribution being the most variable feature. The presence or absence of septate fibres and presence and location of silica grains in ray and/or axial parenchyma might eventually allow recognition of individual species or species groups. Bark anatomy offers no diagnostic features for species differentiation. Wood and bark structure of Buchenavia (15 species studied) intergrades fully with that of neotropical Terminalia (5 species studied), thus corroborating results of studies on morphology (Exell ' Stace 1963) and leaf anatomy (Stace, personal communication, 1989) which postulate a very close relationship between the two genera.

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