Disparity in floral traits and breeding systems in the iconic columnar cactus Pachycereus pringlei (Cactaceae)

Pericarp development in fruit of epiphytic cacti: implications for fruit classification and macro-morphology in the Cactaceae

“…When the fruit ripens, the seeds are completely embedded in mucilage, a sticky substance, commonly described as water-soluble pectin-like polysaccharide (Cárdenas et al 1997), deriving from the funiculus and innermost pericarp layers. It has been proposed that the mucilage covering the seeds of epiphytic and terrestrial cacti is advantageous in stressed environments, particularly in areas with limited water supply, such as the tree canopies and open dry desert areas, in providing a moist exterior protective layer for the seed and embryo against high temperatures and desiccation (Almeida et al 2013b;Gutiérrez-Flores et al 2017). Also, this palatable, slimy substance may facilitate the seed ingestion and passage through the digestive tract of frugivorous…”

Variation in chromosome number and breeding systems: implications for diversification in Pachycereus pringlei (Cactaceae)

“…Unlike most cacti, this taxon exhibits variation in genders and breeding systems (Fleming et al 1998, Medel-Narváez 2008, Gutiérrez-Flores et al 2016, 2017). While the vegetative morphological variability in this species is seemingly conservative to the extent that the species can be easily recognized by these attributes, the existence of polymorphism in floral traits associated with breeding systems and geographic distribution of populations is highly diverse, suggesting reproductive isolation (Gutiérrez-Flores et al 2017).…”

“…Unlike most cacti, this taxon exhibits variation in genders and breeding systems (Fleming et al 1998, Medel-Narváez 2008, Gutiérrez-Flores et al 2016, 2017). While the vegetative morphological variability in this species is seemingly conservative to the extent that the species can be easily recognized by these attributes, the existence of polymorphism in floral traits associated with breeding systems and geographic distribution of populations is highly diverse, suggesting reproductive isolation (Gutiérrez-Flores et al 2017). Recent studies of neutral genetic variation (Gutiérrez-Flores 2015, Gutiérrez-Flores et al 2016) identified five genetic populations of P. pringlei unexpectedly associated with different breeding systems, namely two hermaphrodite populations restricted to Catalana and Cerralvo Islands in the Gulf of California, a mainly dioecious assemblage in Cabo San Lucas (CBS) at the tip of the BCP, another trioecious cohort from CBS to northern BCP (~28°N), and a mostly gynodioecious population in northern BCP and the coast of Sonora in mainland Mexico.…”

“…The biogeographic distribution pattern of P. pringlei has been driven by longstanding climatic fluctuations associated with differential colonization abilities of genders, geographic variation of selfing and outcrossing rates, and the effect of biotic and abiotic factors (Gutiérrez-Flores et al 2016, 2017). As a result, the spatial segregation of genders in P. pringlei has long been a magnet to ecologists, geneticists, and systematists (Fleming et al 1994, 1998, Molina-Freaner et al 2003, Gutiérrez-Flores et al 2016, 2017).…”

“…As a result, the spatial segregation of genders in P. pringlei has long been a magnet to ecologists, geneticists, and systematists (Fleming et al 1994, 1998, Molina-Freaner et al 2003, Gutiérrez-Flores et al 2016, 2017). Even so, several important evolutionary questions, such as the distribution of chromosome numbers and whether the diploid condition is dominant over a polyploid condition influencing the evolution and diversity of this cactus, remain unclear.…”