Atypical distyly in Psychotria goyazensis Mull. Arg. (Rubiaceae), an intramorph self-compatible species

Abstract

Distyly is a genetically controlled fl oral dimorphism, characterized by the reciprocal positioning of pin and thrum morphs, a heteromorphic incompatibility system and a balanced morph ratio (isoplethy). Th is study aimed to investigate the phenology, features of distyly, reproductive biology, and fl oral visitors of Psychotria goyazensis Mull. Arg. (Rubiaceae), an intramorph self-compatible species, in a tropical semideciduous forest in the municipality of Catalão, located in the state of Goiás, Brazil. Th e phenology was recorded for a sample of individuals, the fl oral morphology being described using fresh and fi xed material. Th e incompatibility system was tested using controlled hand pollinations. Floral visitors were collected and identifi ed. Blooming began in November 2009 and ended in April 2010. Fruits developed from December 2009 to March 2010. Th e population presented atypical distyly, because only plants with pin fl owers were found. Th e intramorph and open pollinations set more fruits than did spontaneous self-pollinations. Th e main fl ower visitors were Systropus sp. (Diptera), as well as Hymenoptera and Lepidoptera species. Morphological variations in distyly can occur by breakdown/permutation of the gene that controls the polymorphism. However, some authors argue that, in Rubiaceae, genetic control of the incompatibility system can operate independently of the morphological factor, and species might respond in diff erent ways to the same selective pressures.

Floral biology, reciprocal herkogamy and breeding system in fourPsychotriaspecies (Rubiaceae) in Brazil

“…These morphological and physiological characteristics were considered linked in the early literature (Darwin, ; Ganders, ; Barrett, ), but research on various plant groups has shown that the morphological syndrome and incompatibility system are not always genetically associated (Pérez‐Barrales et al ., ; Ferrero et al ., ; Santos‐Gally, Gonzalez‐Voyer & Arroyo, ). In the present study, we described variation in flower morphology, reciprocity and the place of the incompatibility reaction in several heterostylous species of Psychotria , a genus with substantial variation in the expression of the polymorphism (Faivre & McDade, ; Oliveira, ; Sakai & Wright, ; Consolaro et al ., ; Rodrigues & Consolaro, ).…”

“…In Rubioideae, Psychotria L. is the most important genus and heterostyly appears to be an ancestral condition, as shown at the family level in a phylogenetic context (Robbrecht, ; Hamilton, ; Ferrero et al ., ). At the generic level, Psychotria shows substantial variation in the expression of the polymorphism across species and populations, physiologically (variation in incompatibility system) and morphologically (variation in the matching between reciprocal organs) (Sakai & Wright, ; Consolaro, Silva & Oliveira, ; Faria et al ., ; Naiki, ; Rodrigues & Consolaro, ).…”

Theoretical predictions of plant-pollinator interactions in sympatric species of Psychotria (Rubiaceae) in Cerrado of Brazil

“…The genus Psychotria is predominantly heteromorphic and selfincompatible, meaning that fruit formation can only occur through crosses between long-styled and short-styled flowers. Heterostylous flowers are mostly pollinated by bees, but may also be pollinated by many other animal groups, such as flies, moths, butterflies and hummingbirds (Rodrigues & Consolaro 2013, Castro & Oliveira 2002, Ganders 1979, Richards & Koptur 1993). Psychotria species are pollinated more efficiently by lepidopterans and bees (Castro & Oliveira 2002, Coelho & Barbosa 2004, Consolaro et al 2011, Sá 2013, Lopes & Buzato 2005, Mesquita-Neto 2013, Oliveira 2008, Ramos & Santos 2006, Teixeira & Machado 2004.…”

Inacurácia em espécies distílicas de Rubiaceae

“…Thus, we may even speculate that the higher imprecision and smaller pollen receipt of thrum stigmas may, in the long term, lead to some sort of atypical distyly such as pin-monomorphism, commonly found in Rubiaceae (e.g. Sobrevila et al 1983;Faivre & McDade 2001;Rodrigues et al 2013;Sá et al 2016;Costa et al 2017). As mentioned, this may be mediated by the acquisition of other characteristics such as loss of self-incompatibility .…”

“…Despite established in some groups, variations within the distylous populations are common (Sobrevila et al 1983;Faivre and McDade 2001;Santos et al 2008;Coelho et al 2003;Pereira et al 2006;Costa et al 2017;Rodrigues et al 2013;Sugawara et al 2013;Brys and Jacquemyn 2015;Sá et al 2016) and reasons for these variations are less well defined. Variations are observed when the environment is under ecological pressure or disturbances, such as the habitats fragmentation ).…”