A Review of Current Knowledge of Zamiaceae, With Emphasis on Zamia From South America

Abstract

Zamiaceae, a family of the ancient order Cycadales, is distributed throughout the tropical and subtropical regions of both the Old and New Worlds. Here, we present a systematic review of Zamiaceae with emphasis on Zamia species from South America. We aim to (a) establish the current knowledge, (b) identify research gaps, and (c) indicate directions for future studies, discussing ecology and conservation of South America species. The search recovered 508 papers, further classified into 11 research topics: taxonomy and systematics, morphology, biochemistry, genetics, phylogeography, population ecology, reproductive biology, ecological interactions, plant propagation, conservation, and reviews. The number of publications doubled in the 21st century, mostly focusing on genetics (n ¼ 60), taxonomy and systematics (n ¼ 52), morphology (n ¼ 36), ecological interactions (n ¼ 30), and an increasing interest in population ecology (n ¼ 29) and conservation (n ¼ 32). Studies are concentrated in North and Central America (54% of all studies) with just 6% (29) addressing South America species of Zamia. Overall, studies point out the key role of pollinators in promoting gene flow through pollen dispersal among populations of Zamiaceae. Therefore, investigate natural history, ecology, reproductive biology, genetic, and phylogeography, especially for South America species, are needed. Moreover, the implementation of in situ and ex situ collections and germplasm banks linked to botanical gardens are essential for the conservation and reestablishment of local populations of critically endangered Zamia species in South America. Concomitantly, we suggest studies modeling the distribution of Zamia species in future climate change scenarios.

Reproductive biology of the South American cycad Zamia boliviana, involving brood‐site pollination

“…Pharaxonotha cerradensis also used Zamia reproductive organs to reproduce, characterizing the brood‐site pollination mutualism. This study adds to the current body of knowledge accumulated over the last three decades suggesting that insects are the primary pollination vectors of cycads, and that the role of wind in pollinating New World cycads is negligible (Segalla et al, 2019; Tang, Xu, et al, 2018). Thus, our findings provide evidence that the conservation management of cycads must include management of their pollinators, especially for highly threatened species such as this Zamia of the Cerrado, a South American ecosystem with a high frequency of habitat loss.…”

“…The most common beetle visitors of cycads strobilis, palm flowers and Annonaceae species are the weevils from the Curculionidae family (Barfod et al, 2011; Chen, Liu, & Saunders, 2020). Exclusive pollination by beetles (or more rarely thrips) that breed on plant tissues is a common condition in palms (De Medeiros et al, 2019), as in Zamiaceae species (Segalla et al, 2019).…”

“…In members of Zamiaceae, there is a striking sexual dimorphism in the reproductive structures of the two sexes (Grobbelaar, 2002; Jones, 2002; Segalla, Telles, Pinheiro, & Morellato, 2019). The reliance on specialized and obligatory biotic vectors for reproduction increases the risks of reproductive failure for both plant and pollinator.…”

“…The reliance on specialized and obligatory biotic vectors for reproduction increases the risks of reproductive failure for both plant and pollinator. The reproductive biology of the Zamiaceae family (Cycadales) is characterized by cross‐pollination and predominantly obligatory and specialized mutualistic interactions between pollinators and their host plants, in some cases described as a cycad brood‐site pollination mutualism (Hall, Walter, Bergstrom, & Machin, 2004; Norstog & Fawcett, 1989; Norstog, Stevenson, & Niklas, 1986; Segalla et al, 2019; Suinyuy, Donaldson, & Johnson, 2009; Tang, 1987; Terry, 2001; Terry et al, 2005; Toon, Terry, Tang, Walter, & Cook, 2020; Valencia‐Montoya, Tuberquia, Guzmán, & Cardona‐Duque, 2017; Vovides, 1991).…”

“…Despite their rarity and fascinating biological history, cycads are among the most threatened groups of plants worldwide (IUCN, International Union for Conservation of Nature and Natural Resources, 2019; Stevenson, Stanberg, & Calonje, 2018). The codependency on specialized mutualism may render both insect and cycad especially sensitive to the properties associated with cycad population declines (Lopez‐Gallego, 2015; Segalla et al, 2019; Terry et al, 2005, 2012). The ancient origins of cycads provide an opportunity to study the evolution and diversity of plant pollination systems (Terry et al, 2005).…”