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Abstract Detail

Ecological diversification and niche evolution in the temperate zone’s largest genus: Carex

Escudero, Marcial [1], Hahn, Marlene [2], Brown, Bethany [2], Lueders, Kate [2], Arroyo, Juan M. [1], Jordano, Pedro [1], Hipp, Andrew L. [2].

Is chromosome differentiation a driver of ecological diversification at microevolutionary scale?

Carex (Cyperaceae), with ca. 2100 species, constitutes the largest genus of flowering plants in the northern temperate zone. Several authors have suggested a link between Carex species richness and chromosome radiation (2n = 12--124). The goals of our research are to answer three fundamental questions: 1) Do the population dynamics of sedges allow for rapid establishment of chromosome variants, even in the face of potential underdominance of those mutations? 2) To what extent do chromosome rearrangements decrease the fitness of interpopulation crosses? and 3) Do chromosome rearrangements protect ecologically significant genome regions from recombination?
Carex helodes (Carex sect. Spirostachyae) is restricted to southwestern Iberian Peninsula and northern Morocco and its chromosome number ranges from 2n = 68 to 74. We will present preliminary results of a study of within population dynamics in this cytogenetically variable sedge. Carex scoparia (Carex sect. Ovales) is distributed in the northern half of North America and ranges in chromosome number from 2n = 56 to 70. We produced a series of cytogenetic hybrid F1 crosses by cross-pollinating individuals that differ in chromosome number, as well as control crosses between individuals that exhibit no differences. Our results suggest that hybrid dysfunction may play a role in preventing gene flow among individuals that differ by three or more chromosome rearrangements. We then produced an F2 cross from two of the parents and generated a RADseq linkage map based on 191 samples (including parents 2n = 64 and 2n = 66, 5 F1 individuals and 184 F2 individuals). Our results demonstrated that alleles do not segregate in Mendelian fashion in three of the 32 observed linkage groups, which suggests that meiotic selection very likely plays a role in the evolution of chromosome variability in Carex. Our results strongly implicate chromosome evolution as a driver of the ecological and lineage diversity we see in Carex.

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1 - Estación Biológica de Doñana (EBD - CSIC), Integrative Ecology, Americo Vespucio sn, Seville, 41010, Spain
2 - The Morton Arboretum, 4100 Illinois Route 53, Lisle, IL, 60532, USA

hybrid dysfunction
population dynamics
postzygotic barrier
meiotic selection
prezygotic barrier
linkage mapping
Seed germination.

Presentation Type: Symposium Presentation
Session: SY15
Location: Salon 11/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 9:15 AM
Number: SY15004
Abstract ID:472
Candidate for Awards:None

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