Patterns of contemporary hybridization inferred from paternity analysis in a four-oak-species forest

<p>Abstract</p> <p>Background</p> <p>Few studies address the issue of hybridization in a more than two-species context. The species-rich <it>Quercus </it>complex is one of the systems which can offer such an opportunity. To investigate the contemporary pattern of hybridization we sampled and genotyped 320 offspring from a natural mixed forest comprising four species of the European white oak complex: <it>Quercus robur</it>, <it>Q. petraea</it>, <it>Q. pubescens</it>, and <it>Q. frainetto</it>.</p> <p>Results</p> <p>A total of 165 offspring were assigned unambiguously to one of the pollen donors within the study plot. The minimum amount of effective pollen originating from outside the plot varied markedly among the seed parents, ranging from 0.18 to 0.87. The majority of the successful matings (64.1%) occurred between conspecific individuals indicating the existence of reproductive barriers between oak species. However, the isolation was not complete since we found strong evidence for both first-generation (8.4%) and later-generation hybrids (27.5%). Only two out of eight seed parents, belonging to <it>Q. petraea </it>and <it>Q. robur</it>, showed a high propensity to hybridize with <it>Q. pubescens </it>and <it>Q. petraea</it>, respectively. Significant structure of the effective pollen pools (<it>Φ</it>_{<it>pt </it>}= 0.069, P = 0.01) was detected in our sample. However, no support was found for the isolation by distance hypothesis. The proportion of hybrids was much higher (79%) in the seed generation when compared to the adult tree generation.</p> <p>Conclusion</p> <p>First-generation hybrids were observed only between three out of six possible species combinations. Hybrids between one pair of species preferred to mate with one of their parental species. The observation of first and later-generation hybrids in higher frequency in acorns than in adults might be explained by selection against hybrid genotypes, the history of this uneven-aged forest or past introgression between species.</p

Evidence for hybridization and introgression within a species-rich oak (Quercus spp.) community

<p>Abstract</p> <p>Background</p> <p>Analysis of interspecific gene flow is crucial for the understanding of speciation processes and maintenance of species integrity. Oaks (genus <it>Quercus</it>, <it>Fagaceae</it>) are among the model species for the study of hybridization. Natural co-occurrence of four closely related oak species is a very rare case in the temperate forests of Europe. We used both morphological characters and genetic markers to characterize hybridization in a natural community situated in west-central Romania and which consists of <it>Quercus robur</it>, <it>Q. petraea</it>, <it>Q. pubescen</it>s, and <it>Q. frainetto</it>, respectively.</p> <p>Results</p> <p>On the basis of pubescence and leaf morphological characters ~94% of the sampled individuals were assigned to pure species. Only 16 (~6%) individual trees exhibited intermediate morphologies or a combination of characters of different species. Four chloroplast DNA haplotypes were identified in the study area. The distribution of haplotypes within the white oak complex showed substantial differences among species. However, the most common haplotypes were present in all four species. Furthermore, based on a set of 7 isozyme and 6 microsatellite markers and using a Bayesian admixture analysis without any a priori information on morphology we found that four genetic clusters best fit the data. There was a very good correspondence of each species with one of the inferred genetic clusters. The estimated introgression level varied markedly between pairs of species ranging from 1.7% between <it>Q. robur </it>and <it>Q. frainetto </it>to 16.2% between <it>Q. pubescens </it>and <it>Q. frainetto</it>. Only nine individuals (3.4%) appeared to be first-generation hybrids.</p> <p>Conclusion</p> <p>Our data indicate that natural hybridization has occurred at relatively low rates. The different levels of gene flow among species might be explained by differences in flowering time and spatial position within the stand. In addition, a partial congruence between phenotypically and genetically intermediate individuals was found, suggesting that intermediate appearance does not necessarily mean hybridization. However, it appears that natural hybridization did not seriously affect the species identity in this area of sympatry.</p

The Grizzly, October 26, 2017

History of Halloween • Senior English Majors go Gothic • SAO Plans Halloween Trip to Dorney • Senior Halloween Party: An Ursinus Tradition • Fright Night: Phoenixville Theatre Hosts Horror Film Series • Spooky Ursinus Folk • Something Wicked This Way Comes • Opinions: A Ghost Story Haunts with Quiet Pain and Loss; Trick-or-Treating Should End for Children Older than Thirteen • Superstitions Win Confidence for Ursinus Student Athletes • First Year Athletes Face Scary New Adjustmentshttps://digitalcommons.ursinus.edu/grizzlynews/1629/thumbnail.jp

The Grizzly, September 21, 2017

CSCG Brings Biologist and Policy Maker Nina Federoff to Campus • Students Surprised by New Student Senate Requirements • International Film Festival Kicks Off • Q&A with Dean Mark Schneider • Beekeeping Society Creates Some Buzz • Final Member of Pi Omega Delta • Opinions: First-year Perspective: Challenge Yourself with New Experiences; How to be Involved but not Over-committed on Campus • Electric Start for UC Men\u27s Cross Country • Party of Five: Women\u27s Golf Wins First Matchhttps://digitalcommons.ursinus.edu/grizzlynews/1625/thumbnail.jp

The Grizzly, September 14, 2017

Three Workers Injured in IDC Construction Accident • Rush Week Comes Early This Year • Have You Seen Scene / Unseen? • Ursinus Welcomes a New AD to Main Street • A Fairy Tale in the English Department • Opinions: Trump\u27s Move to End DACA is One of his Most Disgusting Acts Yet; Why Resident Advisers Could Benefit From a Union • Fresh Voice for UC Volleyball • Bears Beat Bison and Bullets for Hot Start to Seasonhttps://digitalcommons.ursinus.edu/grizzlynews/1624/thumbnail.jp

The Grizzly, November 16, 2017

Democrats Sweep Local Elections • Sustainability Office Recognized by the Princeton Review • Bear2Bear Fund Aids Students with Emergency Expenses • UCDC Fall Show, Once Removed, Opens This Thursday • Pride Shines at Ursinus • Build Character, Write Now • Opinions: Student Leaders Must be Better Allies Through Their Actions; Paradise Papers Reveal Unethical Tax Avoidance by Tech Companies • UCXC Finishes Strong • Men\u27s Basketball Picked Fourth in Preseason Pollhttps://digitalcommons.ursinus.edu/grizzlynews/1632/thumbnail.jp

The Grizzly, September 7, 2017

Exciting Changes Coming to the Institute for Inclusion and Equity • New Real Estate Opens up at the Berman Museum • Ursinus Receives Grant for New Christian Studies Program on Campus • Writing for the Invisible: Dr. Keita Awarded a Pew Fellowship • First-year Advising is on Beat: Dr. Holly Hubbs Receives Award for Excellence • Opinions: Removing Confederate Statues Condemns White Supremacy; Fall Orientation Starts the Semester with Efficiency • Women\u27s Soccer Gets New Leader in Ascolese • Bears Top Pick for Centennial Conferencehttps://digitalcommons.ursinus.edu/grizzlynews/1623/thumbnail.jp

The Grizzly, April 12, 2018

The Distance Between Us : Ursinus Welcomes Mexican-American Author Reyna Grande • Lantern Launch Celebrates All Things Creative About Ursinus • Berman Museum Opens Annual Student Exhibition • International Perspective: Easter Festivities in Prague Recall Student\u27s Childhood Celebrations • Senior Awarded Fulbright Scholarship • Students Present at Celebration of Student Achievement • Summer Looks Bright for Dr. Lori Daggar • Opinions: Ursinus Needs More Science Labs for Humanities Students; Facebook\u27s Data Scandal Reveals Need for Privacy Protection • Men\u27s Lax Maintains Optimism Amid Rocky Season • T&F Impresses in Outdoor Openerhttps://digitalcommons.ursinus.edu/grizzlynews/1644/thumbnail.jp

Comparing genetic diversity in three threatened oaks

Genetic diversity is a critical resource for species’ survival during times of environmental change. Conserving and sustainably managing genetic diversity requires understanding the distribution and amount of genetic diversity (in situ and ex situ) across multiple species. This paper focuses on three emblematic and IUCN Red List threatened oaks (Quercus, Fagaceae), a highly speciose tree genus that contains numerous rare species and poses challenges for ex situ conservation. We compare the genetic diversity of three rare oak species-Quercus georgiana, Q. oglethorpensis, and Q. boyntonii-to common oaks; investigate the correlation of range size, population size, and the abiotic environment with genetic diversity within and among populations in situ; and test how well genetic diversity preserved in botanic gardens correlates with geographic range size. Our main findings are: (1) these three rare species generally have lower genetic diversity than more abundant oaks; (2) in some cases, small population size and geographic range correlate with genetic diversity and differentiation; and (3) genetic diversity currently protected in botanic gardens is inadequately predicted by geographic range size and number of samples preserved, suggesting non-random sampling of populations for conservation collections. Our results highlight that most populations of these three rare oaks have managed to avoid severe genetic erosion, but their small size will likely necessitate genetic management going forward