Genetic Patterns of Zamia in Florida Are Consistent with Ancient Human Influence and Recent Near Extirpation

Abstract

Premise of research:The only cycad native to the continental United States, Zamia integrifolia, is a taxonomically controversial species with a long history of use by people culminating in near-extirpation 100 years ago. We sought to illuminate the geographic and Click here to access/download;Manuscript;Revision Zamia Florida 09282021.docx

From “Cycad Hell” to Sacred Landscapes: Tracing the Cultural Significance of Cycads in the Ryukyu Islands and Japan

“…19-20 kya, it is also possible, given the timeframe for colonization of the Ryukyus ca. 35-30 kya, that human groups could have mediated gene flow and facilitated the spread of cycads in the region, as has been recently described for Zamia integrifolia in Florida (Griffith et al 2022).…”

“…If further research can confirm the antiquity of these relic landscapes, it may assist in elucidating questions regarding the human colonization of the islands and the place of cycads in preagricultural subsistence strategies and prehistoric Ryukyuan diets, as well as the relationship between the Pleistocene and Holocene populations in the Ryukyus, all of which are subjects on which there is considerable current debate (Fujita et al 2016; Fujita, Yamasaki, and Sawaura 2020; Takamiya and Nakamura 2020; Takamiya et al 2016; Takamiya et al 2019). Of particular note are the population genetics and phylogeographical studies of C. revoluta and C. taitungensis and their divergence (Chang, Huang, and Liao 2019; Chang et al 2022; Chiang et al 2009; Chiang and Schaal 2006; Kyoda and Setoguchi 2010). While these authors attribute the low genetic diversity and marked geographical structure in haplotype groups among these species to environmental and geological fluctuations following the end of the Last Glacial Maximum ca.…”

“…Distributional comparison between C. revoluta haplotype groups (pattern beginning ca. 19 kya) (left; after Kyoda and Setoguchi 2010: 185, Figure 4) and Shellmidden middle Early 4 (ca. 1500 BCE) pottery in the Ryukyu Islands (right; after Takamiya et al 2016: 10, Figure 6).…”

“…Cycas revoluta , which together with its sister species C. taitungensis constitute the Asiorientalis section of the genus (Hill 2004), is widely distributed across the Ryukyu arc, usually along rocky coasts, from southern Kyushu through the Ryukyus and parts of southern China (Osborne and Tomiyama 1995; Whitelock 2002; Yamazaki 1995). Genetic studies have demonstrated that both species are native to the Ryukyu archipelago, having diverged allopatrically during the postglacial transgression (Chang, Huang, and Liao 2019; Chang et al 2022; Chiang and Schaal 2006; Chiang et al 2009; Kyoda and Setoguchi 2010). Cycad biology makes them especially hardy and resilient plants, able to thrive in a variety of marginal ecosystems and rocky soils of generally poor quality (Norstog and Nicholls 1997).…”

Speciation and conservation genetic assessment of two endangered cycad species

“…Furthermore, it is mysterious that some species pairs are morphologically similar but can be recognized using molecular markers (i.e., cryptic species) (Bickford et al, 2007), such as species in Taxus (Taxaceae) (Liu et al, 2011), Pinus armandii Franch. (Pinaceae) (Liu et al, 2019), Zamia integrifolia L.f. (Zamiaceae) (Griffith et al, 2022), and Potamogeton (Potamogetonaceae) (Fehrer et al, 2022). Comparing patterns of intra‐ and interspecific genetic differentiation between species with similar morphology holds considerable significance in unraveling the mechanisms underlying their speciation process.…”