Boundaries and Barriers of North American Warm Deserts: An Evolutionary Perspective

2008 ◽  
Vol 58 (2) ◽  
pp. 257-273 ◽  
Author(s):  
Michelle. Mattern ◽  
Hans Van Gossum

AbstractSex-limited polymorphism is widely distributed among animal taxa, but has only rarely been studied from a macro-evolutionary perspective. We investigate the evolution of female-limited polymorphism by mapping presence or absence of multiple discrete morphs on published phylogenetic trees for North American representatives of two damselfly genera. The results indicate that female polymorphy represents the ancestral condition based on the species included with subsequent loss and monomorphy representing the evolutionary end-point in most cases. According to one phylogeny, character optimization suggests that expression of the polymorphism may be lost (to a state of monomorphy) and gained again (back to polymorphy). Earlier work indicated that changes from polymorphy to monomorphy might be coupled with evolution of the mating system from polyandry to monandry. The results presented here, however, do not convincingly support such view.


2020 ◽  
Vol 29 (2) ◽  
pp. 259-264 ◽  
Author(s):  
Hasan K. Saleh ◽  
Paula Folkeard ◽  
Ewan Macpherson ◽  
Susan Scollie

Purpose The original Connected Speech Test (CST; Cox et al., 1987) is a well-regarded and often utilized speech perception test. The aim of this study was to develop a new version of the CST using a neutral North American accent and to assess the use of this updated CST on participants with normal hearing. Method A female English speaker was recruited to read the original CST passages, which were recorded as the new CST stimuli. A study was designed to assess the newly recorded CST passages' equivalence and conduct normalization. The study included 19 Western University students (11 females and eight males) with normal hearing and with English as a first language. Results Raw scores for the 48 tested passages were converted to rationalized arcsine units, and average passage scores more than 1 rationalized arcsine unit standard deviation from the mean were excluded. The internal reliability of the 32 remaining passages was assessed, and the two-way random effects intraclass correlation was .944. Conclusion The aim of our study was to create new CST stimuli with a more general North American accent in order to minimize accent effects on the speech perception scores. The study resulted in 32 passages of equivalent difficulty for listeners with normal hearing.


2006 ◽  
Vol 175 (4S) ◽  
pp. 511-512
Author(s):  
David G. McLeod ◽  
Ira Klimberg ◽  
Donald Gleason ◽  
Gerald Chodak ◽  
Thomas Morris ◽  
...  

2006 ◽  
Vol 175 (4S) ◽  
pp. 46-47
Author(s):  
Daniel J. Lewinshtein ◽  
K.-H. Felix Chun ◽  
Alberto Briganti ◽  
Hendrik Isbarn ◽  
Eike Currlin ◽  
...  

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