HOLOCHROMEVOL

HOLOCENTRIC CHROMOSOME EVOLUTION AND THE ORIGINS OF BIODIVERSITY IN A HYPER-DIVERSE PLANT LINEAGE

Coordinatore	AGENCIA ESTATAL CONSEJO SUPERIOR DE INVESTIGACIONES CIENTIFICAS    more  Organization address address: CALLE SERRANO 117 city: MADRID postcode: 28006 contact info Titolo: Mr. Nome: Alberto Cognome: Sereno Alvarez Email: send email Telefono: +34 91 566 8852 Fax: +34 91 566 89 13
Nazionalità Coordinatore	Spain [ES]
Totale costo	213˙266 €
EC contributo	213˙266 €
Programma	FP7-PEOPLE Specific programme "People" implementing the Seventh Framework Programme of the European Community for research, technological development and demonstration activities (2007 to 2013)
Code Call	FP7-PEOPLE-2011-IOF
Funding Scheme	MC-IOF
Anno di inizio	2012
Periodo (anno-mese-giorno)	2012-10-01   -   2015-03-31

 Partecipanti

#	participant	country	role	EC contrib. [€]
1	AGENCIA ESTATAL CONSEJO SUPERIOR DE INVESTIGACIONES CIENTIFICAS  Organization address address: CALLE SERRANO 117 city: MADRID postcode: 28006 contact info Titolo: Mr. Nome: Alberto Cognome: Sereno Alvarez Email: send email Telefono: +34 91 566 8852 Fax: +34 91 566 89 13	ES (MADRID)	coordinator	213˙266.55

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 Obiettivo del progetto (Objective)

'Holocentric chromosomes are commonly referred to as having a diffuse centromere. Holocentric chromosome organization has been described for three of the six supergroups in the domain Eukarya (the Eukaryotes): plants (angiosperms, algae and mosses), animals (numerous arthropod clades, velvet worms, and nematodes), and Rhizaria. It has long been recognized that chromosome fragments that would be lost in monocentric chromosomes may be propagated and become fixed in organisms with holocentric chromosomes. In addition to fission and fusion, which may be only weakly underdominant or nearly neutral in holocentric chromosomes, holocentric chromosome structure facilitates translocations and inversions. In the sedge genus Carex (Cyperaceae), 2n = 12 – 124, chromosome rearrangements contribute to genetic diversity within species. These findings suggest that holocentry is an important determinant of biodiversity patterns in the wide range of lineages in which it occurs. Holocentry undoubtedly also plays an important role in the evolution of recombination rates which may be selected by the environment. There is another dimension to chromosome evolution in organisms with holocentric chromosomes: Chromosome rearrangements may suppress recombination (islands of speciation theory). The goals of this study are to answer four fundamental questions: 1) Do chromosome rearrangements protect ecologically significant genome regions from recombination? 2) To what extent do chromosome rearrangements decrease the fitness of first- and second-generation interpopulation crosses? 3) What are the relative contributions of hybrid dysfunction (decreased fitness of hybrids between individuals with differing chromosome numbers) and recombination suppression to chromosomal speciation? and 4) Do the population dynamics of sedges allow for rapid establishment of chromosome variants, even in the face of underdominance of those mutations?'

Introduzione (Teaser)

Researchers are studying a peculiar type of chromosome to better understand how it influences speciation and evolution.

Descrizione progetto (Article)

Chromosomes, bundles of DNA common to all plants and animals, are held together and controlled via a central area called a centromere. Some plants and animals have a centromere diffused across the length of the chromosome; these chromosomes are referred to as holocentric.

Recent evidence suggests that holocentric chromosomes influence the evolution of the species in which they occur. An EU-funded project, 'Holocentric chromosome evolution and the origins of biodiversity in a hyper-diverse plant lineage' (HOLOCHROMEVOL), is investigating this phenomenon in the common European sedge genus Carex.

With more than 2000 species, Carex is one of the most species-rich genera of angiosperms and the most diverse in the northern temperate zone. The genus has holocentric chromosomes, and so it is likely that these have influenced genetic diversity and species richness in the genus.

The project has conducted long-term breeding experiments with Carex scoparia, both within and between populations. Several generations of offspring were grown, interbred and harvested for further analysis.

High-throughput genetic sequencing (RADseq) was used to obtain linkage maps and evaluate chromosome rearrangements and how this phenomenon related to interbreeding in these plants. Researchers have found that germination rate decreases as chromosomal rearrangements increase.

This is the first evidence that holocentric chromosomes can influence the breeding (and thus the evolution) of an organism. HOLOCHROMEVOL has produced an in vivo model for other scientists to study the relationships between holocentric chromosomes, evolution and speciation.