Did Vicariance Mold Phenotypes of Western North American Fishes? Evidence From Gila River Cyprinids

Abstract

Pairwise, two- and three-way Mantel tests were used to evaluate a null hypothesis of no significant covariation when morphological features of three cyprinid fish taxa of the genus Gila were compared. Tests involved ecological conditions and past and present hydrography in the Gila River Basin of western North America. A vicariance hypothesis was the only model statistically proficient in explaining diversity of fish phenotypes. Of paleohydrographic reconstructions compared, those of the mid-Miocene and Pliocene epochs were significantly associated with present-day distributions of phenotypes. Of these, the Pliocene was paramount.

Evolutionary Relationships of the Plagopterins (Teleostei: Cyprinidae) from CytochromebSequences

“…This separation might be attributable to habitat isolation because of a proclivity of the genus for hard-bottomed streams, separated by the sand-bottomed, erosive nature of the mainstem lower Gila River. Alternatively, it might also have resulted from isolation in endorheic drainage basins (e.g., Douglas et al, 1999).…”

How well do multivariate data sets match? The advantages of a Procrustean superimposition approach over the Mantel test

“…Due to its simplicity and flexibility, the most common approach used by biologists for assessing the congruence between two multivariate data sets is the test for matrix correlation developed by Mantel (1967;e.g., Douglas and Endler 1982;Manly 1986;Jackson and Harvey 1989;Oden and Sokal 1992;Rosa et al 1995;Thorpe et al 1996;Manly 1997;Rodrígues and Lewis 1997;Douglas et al 1999;Dutilleul et al 2000 and references in). First each multivariate data set is translated into a pairwise distance matrix that expresses the difference between each pair of objects (e.g., species, sites, populations) in a multivariate space.…”

“…We develop this partial PROTEST method as an analogous procedure to a multiple Mantel test or partial Mantel test (Smouse et al 1986;Thorpe et al 1996;Douglas et al 1999), which is an extension of the original test for testing the correlation between two distance matrices where the variation due to one or more matrices is kept fixed (i.e., partial correlation). This approach can be essential in the process of testing the hypothesis of association/causation because it minimizes problems related to spurious correlation, i.e., that the association between two sets of data is largely due to their mutual correlation with other sources of variation rather than to their own.…”

“…Therefore, our simulations were more extensive in creating a larger number of more varied scenarios where the structure within-and between-matrices was more finely examined (Table 1) relative to other studies. We also evaluated the power where multivariate analysis (e.g., PCA) is used as a prelude to performing the tests, a common procedure among evolutionary biologists and ecologists when using the Mantel test (e.g., Jackson and Harvey 1989;Douglas and Matthews 1992;Rodrígues and Lewis 1997;Douglas et al 1999). The results show some benefit in terms of power for both tests when using PCA, especially for matrices with low degrees of association, indicating that it may be advantageous to reduce data dimensionality by applying an ordination prior to testing.…”

“…Community ecologists seek to establish relationships between environmental characteristics and species distribution (e.g., Jackson and Harvey 1993;Rodríguez and Lewis 1997;Jenkins and Buikema 1998). Among systematists a common goal is to determine whether or not spatial distribution is related to phenotypic or genetic differentiation among populations or species (e.g., Douglas and Endler 1982;Douglas et al 1999). These research programs embrace rather different questions and types of multivariate data, but they all involve comparisons between two or more data sets in order to measure their degree of concordance.…”