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Determining an absolute timescale for avian evolutionary history has proven contentious. The two sources of information available, paleontological data and inference from extant molecular genetic sequences (colloquially, 'rocks' and 'clocks'), have appeared irreconcilable; the fossil record supports a Cenozoic origin for most modern lineages, whereas(More)
The estimation and maintenance of connectivity among local populations is an important conservation goal for many species at risk. We used Bayesian statistics and coalescent theory to estimate short- and long-term directional gene flow among subpopulations for two reptiles that occur in Canada as peripheral populations that are geographically disjunct from(More)
SUMMARY Phylogenetic comparative methods are essential for addressing evolutionary hypotheses with interspecific data. The scale and scope of such data have increased dramatically in the past few years. Many existing approaches are either computationally infeasible or inappropriate for data of this size. To address both of these problems, we present geiger(More)
BACKGROUND Stramenopiles constitute a large and diverse eukaryotic clade that is currently poorly characterized from both phylogenetic and temporal perspectives at deeper taxonomic levels. To better understand this group, and in particular the photosynthetic stramenopiles (Ochrophyta), we analyzed sequence data from 135 taxa representing most major(More)
Data from the 1995 National Survey of Family Growth have previously shown greater risk of inconsistent contraceptive pill use among Hispanic women. We used the same data to test aculturally based model of pill use among the subsample of Hispanic women. Hierarchical logit analyses revealed that primary use of Spanish, negative attitudes about women in the(More)
OBJECTIVE This research evaluates the hypothesis that poor health triggers a change in living arrangements among elderly adults in Japan. METHODS Data came from a national probability sample of 2,200 Japanese people aged 60 or older. Four surveys of this sample were conducted over a period of 9 years, from 1987 to 1996. Multinomial logit regression(More)
Succulent plants are widely distributed, reaching their highest diversity in arid and semi-arid regions. Their origin and diversification is thought to be associated with a global expansion of aridity. We test this hypothesis by investigating the tempo and pattern of Cactaceae diversification. Our results contribute to the understanding of the evolution of(More)
OBJECTIVES There is limited knowledge concerning how the effects of socioeconomic status (SES) on mortality interact with gender and age. In addition, current studies are largely based on data from the Western nations. The validity of prior observations needs to be further evaluated. This research examines socioeconomic inequalities in old age mortality in(More)
OBJECTIVE This research examines how physical and mental health influence living arrangements among older Americans and whether these effects differ for married and unmarried persons. METHODS Data came from the Asset and Health Dynamics Among the Oldest Old study. These two intervals were pooled, and hierarchical multinomial logistic regressions were used(More)