Special Issue "Reticulate Evolution"

Guest Editor
Prof. Dr. Michael L. Arnold
Department of Genetics, Life Sciences Building, University of Georgia, Athens, GA 30602, USA
Website: http://www.genetics.uga.edu/people_bio_arnold_m.html
E-Mail:
Interests: reticulate evolution; web of life; speciation; adaptation

Dear Colleagues,

The only illustration in the Origin of Species presents an evolutionary tree with branches that never reconnect. It is now evident that this view does not encompass the richness of the evolutionary process. Instead, the evolution of species from microbes to mammals is often reticulate, building like a web due to genetic exchange events. Some of the avenues for reticulate evolution, for example sexual recombination versus lateral gene transfer, result from different molecular mechanisms. However, even such widely different genetic processes may result in similar effects on the evolutionary/ecological trajectory of organisms. Given the widespread occurrence and thus importance of reticulate evolution, the journal Genes will publish a Special Issue devoted to this topic. Reviews and original papers are welcome. Topics that touch upon the role of reticulate evolution in any organismic group are appropriate for this Special Issue.

Professor Michael L. Arnold
Guest Editor

Submission Information

All manuscripts should be submitted to genes@mdpi.org with a copy to the Guest Editor. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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Please visit the Instructions for Authors page before submitting a manuscript. For the first couple of issues, to be published in 2010, the Article Processing Charges (APC) will be waived for well-prepared manuscripts. English correction and/or formatting fees of 250 CHF (Swiss Francs) will be charged in certain cases for those articles accepted for publication that require extensive additional formatting and/or English corrections.

• reticulate evolution
• hybridization
• introgression
• horizontal transfer
• hybrid speciation
• adaptive trait transfer

Type of Paper: Article
Title: Population Genomics of Secondary Contact
Authors: Anthony Geneva and Daniel Garrigan
Affiliation: Department of Biology, University of Rochester, Rochester, NY, USA; E-Mail: daniel.garrigan@rochester.edu
Abstract: One common form of reticulate evolution can arise as a consequence of secondary contact between previously allopatric populations. Using extensive coalescent simulations, we describe the conditions and extent of introgression of genetic material from a colonizing population into the genomes of an endemic population. The simulated coalescent histories are sampled from models that describe the evolution of entire chromosomes, thereby allowing the expected length of introgressed haplotypes to be estimated. The results indicate that our ability to identify reticulate evolution is highly variable and critically depends upon the duration of the period of allopatry, the timing of the secondary contact event, as well as the sizes of the populations at the time of contact. One particularly interesting result is that if secondary contact occurs close to the time of a severe founder event, genetic introgression is substantially more difficult to detect. However, if secondary contact occurs after such a founding event, when the range of the colonizing population increases, introgression is more readily detectable across the genome.

Type of Paper: Review
Title: The Application of Modern Cytogenetic Methods (FISH/GISH) to the Study of Reticulation (Polyploidy/Hybridization)
Author: Doug Soltis
Affiliation: Department of Biology, University of Florida, USA; E-Mail: dsoltis@botany.ufl.edu
Abstract: The convergence of diverged lineages resulting in hybrid taxa is an important process that has occurred during the evolution of many plants. Hybridisation can be accompanied by increases in ploidy allowing homologous pairing of chromosomes during meiosis. Fluorescence and genomic in situ hybridisation (FISH/GISH) can identify the most likely progenitors of hybrid taxa and reveal a variety of genomic changes that occur following hybridisation and polyploidisation. Recent advances in high-throughput DNA sequencing now allow the transcriptome and the medium to highly repetitive fractions of a genome to be rapidly characterised, thereby providing many potential cytogenetic markers. We review how FISH and GISH can be used to study taxa of hybrid origin, particularly with the increasing availability of plant genomic resources.

Type of Paper: Review
Title: Asymmetric Introgressive Hybridization Among Louisiana Iris Species
Authors: Michael L. Arnold et al.
Affiliation: Department of Genetics, Life Sciences Building, University of Georgia, Athens, GA 30602, USA; E-Mail: arnold@plantbio.uga.edu
Abstract: In this review, we discuss findings from studies carried out over the past 20+ years that document the occurrence of asymmetric introgressive hybridization in a plant clade. In particular, analyses of natural and experimental hybridization have demonstrated the consistent introgression of genes from Iris fulva into both Iris brevicaulis and Iris hexagona. Furthermore, our analyses have detected certain prezygotic and postzygotic barriers to reproduction that appear to contribute to the asymmetric introgression. Finally, our studies have determined that a portion of the genes transferred apparently affects adaptive traits.

Type of Paper: Review
Title: An Infectious Topic in Reticulate Evolution: Introgression and Hybridization in Animal Parasites
Authors: Jillian Detwiler and Charles Criscione
Affiliation: Department of Biology, Texas A&M University, College Station, TX, USA; E-Mail: ccriscione@mail.bio.tamu.edu
Abstract: Little attention has been given to the role that introgression and hybridization have played in the evolution of parasites. Most studies are host-centric and ask if the hybrid of a free-living species is more or less susceptible to parasite infection. Here we focus on what is known about how introgression and hybridization have influenced the evolution of protozoan and helminth parasites of animals. There are a few reports of genome or gene introgression from distantly related taxa into apicomplexans and filarial nematodes. Most common are genetic based reports of potential hybridization among congeneric taxa, but in several cases, more work is needed to definitively conclude current hybridization. In the medically important Trypanosoma it is clear that some clonal lineages are the product of past hybridization events. Similarly, strong evidence exists for hybridization in human helminths such as Schistosoma and Ascaris. There remain topics that warrant further investigation such as the potential hybrid origin of polyploidy platyhelminths. Furthermore, little work has investigated the phenotype or fitness, much less the epidemiological significance of hybrid parasites.