Contingency and determinism in replicated adaptive radiations of island lizards   总被引：2，自引：0，他引：2  

JB Losos  TR Jackman  A Larson  K Queiroz  L Rodriguez-Schettino 《Science (New York, N.Y.)》1998,279(5359):2115-2118

The vagaries of history lead to the prediction that repeated instances of evolutionary diversification will lead to disparate outcomes even if starting conditions are similar. We tested this proposition by examining the evolutionary radiation of Anolis lizards on the four islands of the Greater Antilles. Morphometric analyses indicate that the same set of habitat specialists, termed ecomorphs, occurs on all four islands. Although these similar assemblages could result from a single evolutionary origin of each ecomorph, followed by dispersal or vicariance, phylogenetic analysis indicates that the ecomorphs originated independently on each island. Thus, adaptive radiation in similar environments can overcome historical contingencies to produce strikingly similar evolutionary outcomes.  相似文献   

Root length and nitrate under Sesbania sesban: Vertical and horizontal distribution and variability     

Kindu Mekonnen  Roland J. Buresh  Richard Coe  Kering Maru Kipleting 《Agroforestry Systems》1998,42(3):265-282

Measurements of root and nutrient distributions in agroforestry systems have often been obtained from unreplicated plots. We, therefore, measured the vertical and horizontal distribution of root length and soil nitrate in replicated plots of sesbania [Sesbania sesban (L.) Merr.] to assess plot-to-plot variation and identify appropriate sampling schemes. Sampling was on profile walls exposed from pits at two on-farm sites (Ochinga and Muange) in Kenya. At Ochinga, soil was sampled at 27 0.15-m depth intervals and eight 0.15-m-wide locations perpendicular to 2.25-m-wide rows of 19-month-old sesbania. At Muange, sampling was 18 months after establishment of sesbania from seedlings with a 1 m by 1 m spacing. Soil was sampled at 17 0.15-m depth intervals and nine 0.15-m-wide sampling locations – one exactly below the tree and four each on opposite sides of the tree. Root length density generally decreased with distance from sesbania and with soil depth. Soil nitrate, however, followed different trends in the four replications at Ochinga and the three replications at Muange. At Ochinga, nitrate above 2.5-m depth clearly increased with distance from the tree in two replications but followed no distinct trend in another replication. At Muange, nitrate above 1.2-m depth decreased with distance from the tree in one replication, increased with distance from the tree in another replication and followed no clear trend in another replication. The suitability of various sampling schemes for measuring root length and nitrate was accessed from percent bias between measured values at sampling locations in the scheme and actual values for an entire transect of sampling locations. Bias associated with selection of sampling locations tended to be higher within the 2.25-m-wide sesbania rows than the 1 m by 1 m sesbania spacing. Soil sampling in systems with rows of young trees should be at several locations along a transect perpendicular to tree rows in order to minimize bias. This revised version was published online in June 2006 with corrections to the Cover Date. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

Further investigation of equine fescue oedema induced by Mediterranean tall fescue (Lolium arundinaceum) infected with selected fungal endophytes (Epichloë coenophiala)     

SC Finch  JS Munday  BL Sutherland  JB Vlaming  LR Fletcher 《New Zealand veterinary journal》2013,61(6):322-326

Abstract