Population structure in Neotropical plants: integrating pollination biology, topography and climatic niches

Animal pollinators mediate gene flow among plant populations, but, in contrast to well-studied topographic and (Pleistocene) environmental isolating barriers, their impact on population genetic differentiation remains largely unexplored. Comparatively investigating how these multifarious factors drive microevolutionary histories is, however, crucial for better resolving macroevolutionary patterns of plant diversification. We here combined genomic analyses with landscape genetics and niche modelling across six related Neotropical plant species (424 individuals across 33 localities) differing in pollination strategy to test the hypothesis that highly mobile (vertebrate) pollinators more effectively link isolated localities than less mobile (bee) pollinators. We found consistently higher genetic differentiation (FST) among localities of bee- than vertebrate-pollinated species with increasing geographic distance, topographic barriers and historic climatic instability. High admixture among montane populations further suggested relative climatic stability of Neotropical montane forests during the Pleistocene. Overall, our results indicate that pollinators may differentially impact the potential for allopatric speciation, thereby critically influencing diversification histories at macroevolutionary scales.

Ceratozamia dominguezii (Zamiaceae): A New Cycad Species from Southeastern Mexico

Ceratozamia dominguezii (Zamiaceae), a new species endemic to the lowland karstic tropical rainforests of southeastern Veracruz, Mexico, is described. The new species is part of the C. robusta species complex, a group of closely related species that share unique characteristics in the genus, such as robust trunks, large strobili, and long leaves. Compared with the other species in the complex (i.e., C. robusta, C. leptoceras, C. aurantiaca and C. subroseophylla), C. dominguezii has the longest rachides, and is characterized by having papyraceous leaflets, a unique caramel color in emerging leaves, and a dark-violet color in the central portion of distal faces of male and female sporophylls. Ceratozamia dominguezii occurs within the Uxpanapa floristic refuge, which is hypothesized to have sheltered a numerous group of tropical elements during the Neogene glaciations. The recognition of C. dominguezii contributes to clarifying the present diversity of cycads in the genus Ceratozamia, and adds discussion on the role of floristic refugia in the divergence of Neotropical plants in Mexico.

Disentangling Domestication from Food Production Systems in the Neotropics

The Neolithic Revolution narrative associates early-mid Holocene domestications with the development of agriculture that fueled the rise of late Holocene civilizations. This narrative continues to be influential, even though it has been deconstructed by archaeologists and geneticists in its homeland. To further disentangle domestication from reliance on food production systems, such as agriculture, we revisit definitions of domestication and food production systems, review the late Pleistocene–early Holocene archaeobotanical record, and quantify the use, management and domestication of Neotropical plants to provide insights about the past. Neotropical plant domestication relies on common human behaviors (selection, accumulation and caring) within agroecological systems that focus on individual plants, rather than populations—as is typical of agriculture. The early archaeobotanical record includes numerous perennial and annual species, many of which later became domesticated. Some of this evidence identifies dispersal with probable cultivation, suggesting incipient domestication by 10,000 years ago. Since the Pleistocene, more than 6500, 1206 and 6261 native plant species have been used in Mesoamerica, the Central Andes and lowland South America, respectively. At least 1555, 428 and 742 are managed outside and inside food production systems, and at least 1148, 428 and 600 are cultivated, respectively, suggesting at least incipient domestication. Full native domesticates are more numerous in Mesoamerica (251) than the Andes (124) and the lowlands (45). This synthesis reveals that domestication is more common in the Neotropics than previously recognized and started much earlier than reliance on food production systems. Hundreds of ethnic groups had, and some still have, alternative strategies that do involve domestication, although they do not rely principally on food production systems, such as agriculture.

Historical biogeography of a Brazilian lineage of Tillandsioideae (subtribe Vrieseinae, Bromeliaceae): the Paranaean Sea hypothesized as the main vicariant event

Subtribe Vrieseinae comprise four genera, Alcantarea, Stigmatodon, Vriesea s.s. and Waltillia, encompassing c. 20% of species in Tillandsioideae (Bromeliaceae), almost all of which are exclusive to Brazil. Here, we explore the biogeographic history of Vrieseinae, sampling 21 of the 22 genera of Tillandsioideae (130 terminals) and three DNA sequence markers (two plastid: rps16-trnK and matK; one nuclear: PHYC). We inferred a dated phylogeny and the ancestral areas of this lineage through RASP (reconstruct ancestral state in phylogeny) analyses. Vrieseinae were recovered as monophyletic, but tribe Vrieseeae (subtribe Vrieseinae + subtribe Cipuropsidinae) were not. A vicariant event between the Andes and Brazilian Shield probably occurred c. 10 Mya, when two clades, Cipuropsidineae + Tillandsieae and Vrieseineae, diverged. The Atlantic Forest plus the Chacoan region is recognized as the ancestral area for Vrieseinae. The results confirmed the recent origin of genera of Vrieseinae, with estimated crown ages in the Pliocene (5.3–2.6 Mya). We propose that the Paranaean Sea influenced the divergence of the main clades; Pleistocene events were probably responsible for the diversification of the most recent clades. This study sheds light on the biogeographic history of a key group of Neotropical plants, providing a new hypothesis for the evolution of bromeliads.

A new combination in African Gymnanthes (Euphorbiaceae)

The genus Gymnanthes Swartz (1788: 6, 95), originally considered as Neotropical (Pax & Hoffmann 1912), has recently been expanded to include species from Africa and Asia (Esser 1999, 2001). Previously, the two African species had been included in the separate genus Duvigneaudia Léonard (1959: 15), and were as such revised by Kruijt & Roebers (1996). Léonard (1959) had described the genus because these species were clearly distinct from all other African genera, but he did not compare any Neotropical plants, much like Kruijt & Roebers (1996). Also the World Checklist of Euphorbiaceae (Govaerts et al. 2000) accepted the genus as distinct. However, the African species hardly differ from many species of Neotropical Gymnanthes by any significant characters of the leaves and flowers, and although they have somewhat larger fruits, this does not seem to be sufficient to uphold Duvigneaudia as a separate genus. Therefore both genera were united by Esser (1999, 2001). Within Neotropical Gymnanthes, Duvigneaudia is most similar to the former genus Sarothrostachys Klotzsch (1841) from Brazil.

A new combination in African Gymnanthes (Euphorbiaceae)

The genus Gymnanthes Swartz (1788: 6, 95), originally considered as Neotropical (Pax & Hoffmann 1912), has recently been expanded to include species from Africa and Asia (Esser 1999, 2001). Previously, the two African species had been included in the separate genus Duvigneaudia Léonard (1959: 15), and were as such revised by Kruijt & Roebers (1996). Léonard (1959) had described the genus because these species were clearly distinct from all other African genera, but he did not compare any Neotropical plants, much like Kruijt & Roebers (1996). Also the World Checklist of Euphorbiaceae (Govaerts et al. 2000) accepted the genus as distinct. However, the African species hardly differ from many species of Neotropical Gymnanthes by any significant characters of the leaves and flowers, and although they have somewhat larger fruits, this does not seem to be sufficient to uphold Duvigneaudia as a separate genus. Therefore both genera were united by Esser (1999, 2001). Within Neotropical Gymnanthes, Duvigneaudia is most similar to the former genus Sarothrostachys Klotzsch (1841) from Brazil.