The adaptive value of cued seed dispersal in desert plants: Seed retention and release in Mammillaria pectinifera (Cactaceae), a small globose cactus

Abstract

Serotiny, or delayed seed dispersal, is common in fluctuating environments because it hedges the risks of establishment. Mammillaria pectinifera (Cactaceae) facultatively expels fruits in the year they are produced or retains them to disperse the seed over several years. We tested whether M. pectinifera increased fruit expulsion as a response to increased rainfall. While no fruit expulsion was observed in 1997, a dry year, in the wetter 1998 around 20% of all fruits formed were expelled from the maternal plant. A greenhouse experiment showed that high moisture results in the plants expelling all their fruits. Because in 1998 establishment was five times higher than in 1997, this response seems to be highly adaptive: Active fruit expulsion and consequent seed release increases the probability of establishment during pulses of high precipitation.

Not only size matters: achene morphology affects time of seedling emergence in three heterocarpic species of <i>Anacyclus</i> (Anthemideae, Asteraceae)

“…& Durieu; and Aguado & al., 2012, in Anthemis chrysantha Gay). This mechanism may be advantageous in fluctuating environments such as Mediterranean Climate zones because it increases the probability of establish ment during different pulses of precipitation when the likelihood of establishment success is maximal (Gutterman, 1994;Peters & al., 2009). A similar mechanism was described in A. radiatus (Bastida & al., 2010), and observed in other Anacyclus species, in which achenes dampened by rain are released centripetally, so that unwinged inner achenes may be liberated several months after the outermost.…”

Research Article Quaternary origin and genetic divergence of the endemic cactus Mammillaria pectinifera in a changing landscape in the Tehuacán Valley, Mexico

“…Mature fruits and seeds can be retained within the maternal plant for several years, a phenomenon known as serotiny. Seeds are only released during episodes of high precipitation, increasing the chances of germination and establishment (Peters et al, 2009). Pollination by small insects, serotiny, and gravity dispersal can strongly limit pollen and seed mobility among populations, constraining genetic interchange.…”

“…Populations are distributed in the northern sector of the TVr, and separated by 3.66 to 62.68 km (Valverde and Zavala-Hurtado, 2006). Pollination is carried out by small insects (Valverde PL, unpublished results), and seeds can be retained several years within mature fruits limiting dispersal in space and time (Peters et al, 2009). To date, there have been no attempts to explain the processes responsible for the diversification of mammillarias in the TVr.…”

Diversity and Conservation in the Cactus Family

“…These animals have great vagility, increasing the seed dispersal capacity of these cacti. Globular cacti have a lower seed dispersal capacity because their fruits are eaten by reptiles and insects (Godínez-Alvarez 2004), or they show passive dispersal (Peters et al 2009). These latter traits would lead to a narrower habitat size (Mourelle and Ezcurra 1997;Goettsch and Hernández 2006;Hernández et al 2008).…”