POLLINATION AND GENE FLOW IN WHITE CLOVER, GROWING IN A PATCHY HABITAT

2001 ◽  
pp. 35-40 ◽  
Author(s):  
J.L. Osborne ◽  
I.H. Williams ◽  
A.H. Marshall ◽  
T.P.T. Michaelson-Yeates
2011 ◽  
Vol 17 (4) ◽  
pp. 421-430 ◽  
Author(s):  
Christina L. Løjtnant ◽  
Birte Boelt ◽  
Sabine K. Clausen ◽  
Christian Damgaard ◽  
Per Kryger ◽  
...  

2012 ◽  
Vol 63 (2) ◽  
pp. 155 ◽  
Author(s):  
J. A. De Lucas ◽  
J. W. Forster ◽  
K. F. Smith ◽  
G. C. Spangenberg

White clover is one of the most important pasture legumes in global temperate regions. It is an outcrossing, insect-pollinated species with gene flow occurring naturally between plants. A 2-year study was conducted to assess the relationship between gene flow and physical distance in white clover under field conditions in southern Australia. White clover plants exhibiting a red leaf mark phenotypic trait acted as pollen donors to recipient plants lacking leaf markings at distances up to 200 m distant from the donor plants. Progeny were scored for the dominant red-leafed phenotype and gene flow was modelled. Paternity was confirmed using simple sequence repeat markers. A leptokurtic pattern of gene flow was observed under conditions designed to measure maximised gene flow with the majority of pollination occurring in the first 50 m from the donor pollen source. The combined use of simple sequence repeat and visual markers confirmed that there was also a white clover pollen source in addition to the donor plants. This research confirms the difficulty in ensuring absolute containment of gene flow in an outcrossing species grown in an environment when endemic populations are known to exist.


2018 ◽  
Vol 285 (1883) ◽  
pp. 20181019 ◽  
Author(s):  
Marc T. J. Johnson ◽  
Cindy M. Prashad ◽  
Mélanie Lavoignat ◽  
Hargurdeep S. Saini

Urbanization is a global phenomenon with profound effects on the ecology and evolution of organisms. We examined the relative roles of natural selection, genetic drift and gene flow in influencing the evolution of white clover ( Trifolium repens ), which thrives in urban and rural areas. Trifolium repens exhibits a Mendelian polymorphism for the production of hydrogen cyanide (HCN), a potent antiherbivore defence. We quantified the relative frequency of HCN in 490 populations sampled along urban–rural transects in 20 cities. We also characterized genetic variation within 120 populations in eight cities using 16 microsatellite loci. HCN frequency increased by 0.6% for every kilometre from an urban centre, and the strength of this relationship did not significantly vary between cities. Populations did not exhibit changes in genetic diversity with increasing urbanization, indicating that genetic drift is unlikely to explain urban–rural clines in HCN frequency. Populations frequently exhibited isolation-by-distance and extensive gene flow along most urban–rural transects, with the exception of a single city that exhibited genetic differentiation between urban and rural populations. Our results show that urbanization repeatedly drives parallel evolution of an ecologically important trait across many cities that vary in size, and this evolution is best explained by urban–rural gradients in natural selection.


Nature ◽  
2003 ◽  
Author(s):  
HelenR. Pilcher
Keyword(s):  

Agronomie ◽  
2003 ◽  
Vol 23 (5-6) ◽  
pp. 503-510 ◽  
Author(s):  
Florence Paynel ◽  
Jean Bernard Cliquet

2020 ◽  
Vol 82 ◽  
pp. 199-209
Author(s):  
Mike B. Dodd ◽  
Katherine N. Tozer ◽  
Iris Vogeler ◽  
Rose Greenfield ◽  
David R. Stevens ◽  
...  

The improvement in forage quality and quantity of summer-dry hill country pasture resulting from the introduction of clover is well recognised. However, ensuring the persistence of the commonly availablecultivars is challenging, in the face of seasonal moisture stress, intensive grazing, competition from established well-adapted pasture species, low soil fertility and low soil pH – conditions typical of the East Coast of the North Island. Here we quantify the value proposition associated with the introduction of white clover into a case study on a Gisborne sheep and beef farm, using a six-step process. A topographically explicit approach is taken, using an understanding of the underlying spatial variability, based on a combination of soil and pasture measurements, APSIM simulation modelling of pasture growth and farm system modelling of enterprise performance. We show that from a baseline of a typical low-fertility, diverse species hill country pasture, white clover introduction can increase spring and summer forage consumption by 17%, enabling inclusion of an additional 6-month bull finishing enterprise generating a 32% greater carcass weight production and leading to a 49% improvement in farm system EBIT. This represents a positive net present value of over $360,000 for the original investment in white clover establishment into existing pastures.


Author(s):  
B.R. Watkin

AN Aberystwyth selection of tall fescue (Festuca arundinacea Schreb.), known as S170, was sown with certified New Zealand white clover (Trifolium repens) and re' clover (T. pratense) and compared under sheep grazing with other grass/clover pastures at the Grasslands Division Regional Station at Lincoln (Watkin, 1975) .


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