STATISTICAL ASSESSMENT OF CONGRUENCE AMONG PHYLOGEOGRAPHIC HISTORIES OF THREE AVIAN SPECIES IN THE CALIFORNIA FLORISTIC PROVINCE

Abstract

Comparing phylogeographic histories of codistributed species can reveal how common historical events and processes have influenced lineage diversification across species. Within the California Floristic Province, the phylogeographies of a diversity of plants and animals have been studied; however, only a few bird species have been examined in this region. We compared phylogeographic histories of three species of birdsWrentit (Chamaea fasciata), California Thrasher (Toxostoma redivivum), and White-headed Woodpecker (Picoides albolarvatus)to each other as well as to the phylogeographic histories of other California taxa. Qualitatively comparing phylogeographies of these three species reveals some similarities and some differences. All three species exhibit similar levels of sequence divergence, experienced recent range expansions, and show a division between southern and northern populations in the vicinity of the Transverse Ranges. However, nested-clade phylogeographic analysis suggests that different processes have influenced current patterns of genetic structure in these three species. Other taxa within California show a similar division between northern and southern populations; however, our species did not show concordant geographic breaks elsewhere that have been identified for other species. Using a statistical assessment of concordance, our data showed more agreement across a broader regional scale than among closely spaced populations. Phylogeographic trees of the three species showing relationships among counties were not statistically congruent with each other or with a tree representing other California taxa. However, at the broader level of geomorphic province, the Wrentit and White-headed Woodpecker showed complete concordance. Received 30 June 2006, accepted 5 February 2007. Resumen.La comparacion de la historia filogeografica de las especies con distribuciones similares, puede revelar como los eventos historicos y los procesos comunes que han experimentado estas especies han influenciado la diversificacion de sus linajes. Dentro de la provincia floristica de California, se ha estudiado la filogeografia de diversas plantas y animates; sin embargo, solo se han estudiado unas pocas especies de aves. En este estudio, comparamos la historia filogeografica de tres especies de avesChamaea fasciata, Toxostoma redivivum y Picoides albolarvatus; ademas, comparamos la historia filogeografica de otros taxones califomianos. Las comparaciones cualitativas de la filogeografia entre las tres especies antes mencionadas, revelan algunas diferencias y similitudes. Las tres especies muestran niveles similares de divergencia genetica, presentando, ademas, expansiones recientes en sus rangos de distribucion y mostrando una division entre las poblaciones del norte y del sur en las cercanias de los rangos transversales. Sin embargo, los analisis filogeograficos de clados encajados (NCA) sugieren que los patrones de estructura genetica en estas tres especies han sido determinados por procesos diferentes. Otros taxones dentro de California muestran una division similar entre las poblaciones del norte y del sur; sin embargo, nuestras especies no muestran una interrupcion en otras areas geograficas, las que han sido identificadas en especies con una misma distribucion. Utilizando un analisis estadistico de correspondencia nuestras aves muestran mayor concordancia a traves de una amplia escala regional que entre ^-mail: kburns@sunstroke.sdsu.edu