scholarly journals Allopatric origin of sympatric whitefish morphs with insights on the genetic basis of their reproductive isolation

2021 ◽  
Author(s):  
Bohao Fang ◽  
Paolo Momigliano ◽  
Kimmo Kahilainen ◽  
Juha Merila
Keyword(s):  
Reproductive Isolation ◽  
Adaptive Radiation ◽  
Genetic Basis ◽  
Coregonus Lavaretus ◽  
Gonad Weight ◽  
Ecological Adaptations ◽  
Weight Variation ◽  
Artificial Hybrid ◽  
Spawning Time ◽  
Demographic Modelling

The European whitefish (Coregonus lavaretus) species complex is a classic example of recent adaptive radiation. Here we examine a whitefish population introduced to northern Finnish Lake Tsahkal in late 1960s, where three divergent morphs (viz. littoral, pelagic and profundal feeders) were found ten generations after. Using demographic modelling based on genomic data we show that whitefish morphs evolved during a phase of strict isolation, refuting a rapid symmetric speciation scenario. The lake is now an artificial hybrid zone between morphs originated in allopatry. Despite their current syntopy, clear genetic differentiation remains between two of the three morphs. Using admixture mapping three quantitative trait loci associated with gonad weight variation, a proxy for sexual maturity and spawning time, were identified. We suggest that ecological adaptations in spawning time evolved in allopatry are currently maintaining partial reproductive isolation in the absence of other barriers to gene flow.

Influences on the natural reproduction of whitefish (Coregonus lavaretus) in Lake Constance

2009 ◽  
Vol 66 (4) ◽  
pp. 547-556 ◽  
Author(s):  
Bernd Wahl ◽  
Herbert Löffler
Keyword(s):  
Age Structure ◽  
Lake Constance ◽  
Coregonus Lavaretus ◽  
Low Oxygen ◽  
Stock Size ◽  
Natural Reproduction ◽  
Lake Bottom ◽  
Oxygen Conditions ◽  
Spawning Time ◽  
The Impact

The conditions for the natural reproduction of whitefish ( Coregonus lavaretus ) in Lake Constance have been subject to strong variations during recent decades by the impact of fishing and trophic changes. We analysed fluctuations of stock size, age structure, spawning time, and amount of sampled eggs of this species. The onset of spawning altered because of changes in the age structure of the stock. We found a clear relation of spawning time to the mean age of the annual catch and the November epilimnion temperature. The quantity of eggs sampled from the lake bottom with a dredge is in relation to the number of female spawners and may serve as an early indicator for stock size changes. The proportion of viable eggs on the lake floor correlates with oxygen concentrations in deep water. Extremely low oxygen conditions and an almost total loss of eggs occurred when the nutrient levels were high and oxygen regeneration by vertical winter mixing was weak. A mathematical model serves to interpret the changing abundance of living eggs on the lake bottom over the course of a season and is also used to estimate mortality rates.

The potential for rapid speciation in plants

Genome ◽  
1989 ◽  
Vol 31 (1) ◽  
pp. 203-210 ◽  
Author(s):  
Mark R. Macnair
Keyword(s):  
Reproductive Isolation ◽  
Genetic Architecture ◽  
Genetic Basis ◽  
Natural Populations ◽  
Direct Result ◽  
Epistatic Interactions ◽  
Genetic Changes ◽  
Rapid Speciation ◽  
Genetic Revolution ◽  
Self Fertilization

Speciation involves both ecological adaptation and reproductive isolation. This paper reviews various ways in which plants could achieve reproductive isolation as a direct result of adaptation to prevailing conditions, particularly through changes in flowering time, the adoption of self-fertilization, and changes in flower morphology so that different pollinators are attracted. These characters are likely to have a relatively simple genetic architecture, and there must frequently be genetic variance for them in natural populations. It is argued that speciation could thus be initiated swiftly in plants, without any need for a "genetic revolution" or the fixation of genes with strongly epistatic interactions. Postmating barriers also often have a simple genetic basis in plants, and so could also evolve swiftly if associated with an adaptive response. The nature of the genetic changes associated with speciation in a number of recent speciation events in Layia, Stephanomeria, and Mimulus is reviewed.Key words: Speciation, adaptation, reproductive isolation.

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 Differential Expression in Testis and Liver Transcriptomes from Four Species of Peromyscus (Rodentia: Cricetidae)

2020 ◽  
Vol 12 (1) ◽  
pp. 3698-3709
Author(s):  
Laramie L Lindsey ◽  
Roy N Platt ◽  
Caleb D Phillips ◽  
David A Ray ◽  
Robert D Bradley
Keyword(s):  
Cell Cycle ◽  
Gene Ontology ◽  
Reproductive Isolation ◽  
Differential Expression ◽  
Adaptive Radiation ◽  
Common Ancestor ◽  
Data Set ◽  
Regulatory Processes ◽  
Clade B ◽  
Reproductive Processes

Abstract The genus Peromyscus represents a rapidly diverged clade of Cricetid rodents that contains multiple cryptic species and has a propensity for morphologic conservation across its members. The unresolved relationships in previously proposed phylogenies reflect a suspected rapid adaptive radiation. To identify functional groups of genes that may be important in reproductive isolation in a reoccurring fashion across the Peromyscus phylogeny, liver and testis transcriptomes from four species (P. attwateri, P. boylii, P. leucopus, and P. maniculatus) were generated and differential expression (DE) tests were conducted. Taxa were selected to represent members diverged from a common ancestor: P. attwateri + P. boylii (clade A), and P. leucopus + P. maniculatus (clade B). Comparison of clades (A vs. B) suggested that 252 transcripts had significant DE in the liver data set, whereas significant DE was identified for 657 transcripts in the testis data set. Further, 45 genes had DE isoforms in the 657 testis transcripts and most of these functioned in major reproductive roles such as acrosome assembly, spermatogenesis, and cell cycle processes (meiosis). DE transcripts in the liver mapped to more broad gene ontology terms (metabolic processes, catabolic processes, response to chemical, and regulatory processes), and DE transcripts in the testis mapped to gene ontology terms associated with reproductive processes, such as meiosis, sperm motility, acrosome assembly, and sperm–egg fusion. These results suggest that a suite of genes that conduct similar functions in the testes may be responsible for the adaptive radiation events and potential reoccurring speciation of Peromyscus in terms of reproduction through varying expression levels.

scholarly journals The Genetic Basis of Prezygotic Reproductive Isolation Between Drosophila santomea and D. yakuba Due to Mating Preference

Genetics ◽  
2006 ◽  
Vol 173 (1) ◽  
pp. 215-223 ◽  
Author(s):  
Amanda J. Moehring ◽  
Ana Llopart ◽  
Susannah Elwyn ◽  
Jerry A. Coyne ◽  
Trudy F. C. Mackay
Keyword(s):  
Reproductive Isolation ◽  
Genetic Basis ◽  
Mating Preference

scholarly journals Sympatric, parapatric or allopatric: the most important way to classify speciation?

2008 ◽  
Vol 363 (1506) ◽  
pp. 2997-3007 ◽  
Author(s):  
Roger K Butlin ◽  
Juan Galindo ◽  
John W Grahame
Keyword(s):  
Reproductive Isolation ◽  
Local Adaptation ◽  
Genetic Basis ◽  
Environmental Gradients ◽  
Sympatric Speciation ◽  
Model System ◽  
Littorina Saxatilis ◽  
The Past ◽  
Intertidal Gastropod

The most common classification of modes of speciation begins with the spatial context in which divergence occurs: sympatric, parapatric or allopatric. This classification is unsatisfactory because it divides a continuum into discrete categories, concentrating attention on the extremes, and it subordinates other dimensions on which speciation processes vary, such as the forces driving differentiation and the genetic basis of reproductive isolation. It also ignores the fact that speciation is a prolonged process that commonly has phases in different spatial contexts. We use the example of local adaptation and partial reproductive isolation in the intertidal gastropod Littorina saxatilis to illustrate the inadequacy of the spatial classification of speciation modes. Parallel divergence in shell form in response to similar environmental gradients in England, Spain and Sweden makes this an excellent model system. However, attempts to demonstrate ‘incipient’ and ‘sympatric’ speciation involve speculation about the future and the past. We suggest that it is more productive to study the current balance between local adaptation and gene flow, the interaction between components of reproductive isolation and the genetic basis of differentiation.

scholarly journals Conspecific sperm precedence is reinforced but sexual selection weakened in sympatric populations ofDrosophila

2016 ◽  
Author(s):  
Dean M. Castillo ◽  
Leonie C. Moyle
Keyword(s):  
Sexual Selection ◽  
Reproductive Isolation ◽  
Sperm Competition ◽  
Competitive Ability ◽  
Genetic Basis ◽  
Direct Selection ◽  
Sperm Precedence ◽  
Sympatric Populations ◽  
Selection For ◽  
The Cost

SUMMARYSexual selection is well recognized as a driver of reproductive isolation between lineages. However, selection for increased reproductive isolation could reciprocally change the outcomes of sexual selection, when these processes share a genetic basis. Direct selection for reproductive isolation occurs in the context of ‘reinforcement’, where selection acts to increase prezygotic barriers to reduce the cost of heterospecific matings. Many studies of reinforcement focus on premating reproductive barriers, however postmating traits-such as conspecific sperm precedence (CSP)-can also respond to reinforcing selection. We tested whether i) CSP responded to reinforcing selection, and ii) this response in sympatric populations altered intraspecific sperm competition (ISC) and the strength of sexual selection, with the sister speciesDrosophila pseudoobscuraandD. persimilis. We used sperm competition experiments to evaluate differences in CSP and ISC between two sympatric and two allopatric populations ofD. pseudoobscura. Using multiple genotypes for each population allowed us to estimate not only patterns of phenotype divergence, but also the opportunity for sexual selection within each population. Consistent with a pattern of reinforcement, the sympatric populations had higher mean CSP. Moreover, ISC was altered in sympatric populations, where we observed decreased average offensive sperm competitive ability against conspecific males, allowing less opportunity for sexual selection to operate within these populations. These data demonstrate that strong reinforcing selection for reproductive isolation can have consequences for sexual selection and sexual interactions within species, in these important postmating sperm competition traits.

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