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1. Palms of the past: can morphometric phytolith analysis inform deep time evolution and palaeoecology of Arecaceae?

   https://doi.org/10.1093/aob/mcae068  

   Brightly, W H; Crifò, C; Gallaher, T J; Hermans, R; Lavin, S; Lowe, A J; Smythies, C A; Stiles, E; Wilson_Deibel, P; Strömberg, C_A E (April 2024, Annals of Botany)

   Abstract Background and aimsPalm fossils are often used as evidence for warm and wet palaeoenvironments, reflecting the affinities of most modern palms. However, several extant palm lineages tolerate cool and/or arid climates, making a clear understanding of the taxonomic composition of ancient palm communities important for reliable palaeoenvironmental inference. However, taxonomically identifiable palm fossils are rare and often confined to specific facies. Although the resolution of taxonomic information they provide remains unclear, phytoliths (microscopic silica bodies) provide a possible solution because of their high preservation potential under conditions where other plant fossils are scarce. We thus evaluate the taxonomic and palaeoenvironmental utility of palm phytoliths. MethodsWe quantified phytolith morphology of 97 modern palm and other monocot species. Using this dataset, we tested the ability of five common discriminant methods to identify nine major palm clades. We then compiled a dataset of species’ climate preferences and tested if they were correlated with phytolith morphology using a phylogenetic comparative approach. Finally, we reconstructed palm communities and palaeoenvironmental conditions at six fossil sites. Key resultsBest-performing models correctly identified phytoliths to their clade of origin only 59 % of the time. Although palms were generally distinguished from non-palms, few palm clades were highly distinct, and phytolith morphology was weakly correlated with species’ environmental preferences. Reconstructions at all fossil sites suggested that palm communities were dominated by Trachycarpeae and Areceae, with warm, equable climates and high, potentially seasonal rainfall. However, fossil site reconstructions had high uncertainty and often conflicted with other climate proxies. ConclusionsWhile phytolith morphology provides some distinction among palm clades, caution is warranted. Unlike prior spatially restricted studies, our geographically and phylogenetically broad study indicates phytolith morphology may not reliably differentiate most palm taxa in deep time. Nevertheless, it reveals distinct clades, including some likely to be palaeoenvironmentally informative. 

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2. Halibee fossil assemblages reveal later Pleistocene cercopithecins (Cercopithecidae: Primates) in the Middle Awash of Ethiopia

   https://doi.org/10.1002/ajpa.24637  

   Taylor, Catherine E; Brasil, Marianne F; Monson, Tesla A; Yohler, Ryan M; Hlusko, Leslea J (January 2023, American Journal of Biological Anthropology)

   Abstract ObjectivesThe goals of this study were to describe and interpret two new fossil assemblages of cercopithecin monkeys (n = 328), one from the Faro Daba beds (ca. 100,000 years) and the other one from the Chai Baro beds (>158,000 years old), in the Afar Rift of Ethiopia. Materials and MethodsWe describe the two assemblages and compare them to extant cercopithecin species and the smaller fossil assemblage from Asbole, Ethiopia (ca. 600 ka). We use a population‐based approach to the taxonomy given the unusually large number of specimens. Craniodental and postcranial anatomy are presented. Evidence of locomotor habitus is described and evaluated in a framework of hybridization and postcranial plasticity. ResultsWe attribute all cercopithecin specimens from both beds to cf.Chlorocebusand conclude that the Faro Daba and Chai Baro assemblages likely sample single species at each time horizon. Subtle differences between the two assemblages, mostly in postcranial morphology, are insufficient to justify separation at the species level. DiscussionThe large sample sizes and unique preservational aspects of these two assemblages open a new window into the recent evolution of guenons. Our data indicate that these fossil populations may be ancestral to the cercopithecins currently living in the Afar region of Ethiopia. 

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3. A new fossil Acmopyle with accessory transfusion tissue and potential reproductive buds: Direct evidence for ever‐wet rainforests in Eocene Patagonia

   https://doi.org/10.1002/ajb2.16221  

   Andruchow‐Colombo, Ana; Rossetto‐Harris, Gabriella; Brodribb, Timothy J; Gandolfo, María A; Wilf, Peter (August 2023, American Journal of Botany)

   Abstract PremiseAcmopyle(Podocarpaceae) comprises two extant species from Oceania that are physiologically restricted to ever‐wet rainforests, a confirmed fossil record based on leaf adpressions and cuticles in Australia since the Paleocene, and a few uncertain reports from New Zealand, Antarctica, and South America. We investigated fossil specimens withAcmopyleaffinities from the early Eocene Laguna del Hunco site in Patagonia, Argentina. MethodsWe studied 42 adpression leafy‐shoot fossils and included them in a total evidence phylogenetic analysis. ResultsAcmopyle grayaesp. nov. is based on heterophyllous leafy shoots with three distinct leaf types. Among these, bilaterally flattened leaves uniquely preserve subparallel, linear features that we interpret as accessory transfusion tissue (ATT, an extra‐venous water‐conducting tissue). Some apical morphologies ofA. grayaeshoots are compatible with the early stages of ovuliferous cone development. Our phylogenetic analysis recovers the new species in a polytomy with the two extantAcmopylespecies. We report several types of insect‐herbivory damage. We also transferAcmopyle engelhardtifrom the middle Eocene Río Pichileufú flora toDacrycarpus engelhardticomb. nov. ConclusionsWe confirm the biogeographically significant presence of the endangered West Pacific genusAcmopylein Eocene Patagonia.Acmopyleis one of the most drought‐intolerant genera in Podocarpaceae, possibly due to the high collapse risk of the ATT, and thus the new fossil species provides physiological evidence for the presence of an ever‐wet rainforest environment at Laguna del Hunco during the Early Eocene Climatic Optimum. 

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4. Where did they come from, where did they go? Niche conservatism in woody and herbaceous plants and implications for plant‐based paleoclimatic reconstructions

   https://doi.org/10.1002/ajb2.16426  

   Quirk, Zack J; Smith, Selena Y; Paul_Acosta, R; Poulsen, Christopher J (November 2024, American Journal of Botany)

   Abstract PremiseThe ecological conditions that constrain plants to an environmental niche are assumed to be constant through time. While the fossil record has been used previously to test for niche conservatism of woody flowering plants, additional studies are needed in other plant groups especially since they can provide insight with paleoclimatic reconstructions, high biodiversity in modern terrestrial ecosystems, and significant contributions to agriculture. MethodsWe tested climatic niche conservatism across time by characterizing the climatic niches of living herbaceous ginger plants (Zingiberaceae) and woody dawn redwood (Metasequoia) against paleoniches reconstructed based on fossil distribution data and paleoclimatic models. ResultsDespite few fossil Zingiberaceae occurrences in the latitudinal tropics, unlike living Zingiberaceae, extinct Zingiberaceae likely experienced paratropical conditions in the higher latitudes, especially in the Cretaceous and Paleogene. The living and fossil distributions ofMetasequoialargely remain in the upper latitudes of the northern hemisphere. The Zingiberaceae shifted from an initial subtropical climatic paleoniche in the Cretaceous, toward a temperate regime in the late Cenozoic;Metasequoiaoccupied a more consistent climatic niche over the same time intervals. ConclusionsBecause of the inconsistent climatic niches of Zingiberaceae over geologic time, we are less confident of using them for taxonomic‐based paleoclimatic reconstruction methods like nearest living relative, which assume a consistent climatic niche between extant and extinct relatives; we argue that the consistent climatic niche ofMetasequoiais more appropriate for these reconstructions. Niche conservatism cannot be assumed between extant and extinct plants and should be tested further in groups used for paleoclimatic reconstructions. 

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5. Dispersal Limitation Governs Bacterial Community Assembly in the Northern Pitcher Plant ( Sarracenia purpurea ) at the Continental Scale

   https://doi.org/10.1111/geb.13922  

   Cagle, Grace A; McGrew, Alicia; Baiser, Benjamin; Record, Sydne; Gotelli, Nicholas J; Gravel, Dominique; Bittleston, Leonora S; Young, Erica B; Gray, Sarah M; Freedman, Zachary B (December 2024, Global Ecology and Biogeography)

   ABSTRACT AimEcological theory suggests that dispersal limitation and selection by climatic factors influence bacterial community assembly at a continental scale, yet the conditions governing the relative importance of each process remains unclear. The carnivorous pitcher plantSarracenia purpureaprovides a model aquatic microecosystem to assess bacterial communities across the host plant's north–south range in North America. This study determined the relative influences of dispersal limitation and environmental selection on the assembly of bacterial communities inhabitingS. purpureapitchers at the continental scale. LocationEastern United States and Canada. Time Period2016. Major Taxa StudiedBacteria inhabitingS. purpureapitchers. MethodsPitcher morphology, fluid, inquilines and prey were measured, and pitcher fluid underwent DNA sequencing for bacterial community analysis. Null modelling of β‐diversity provided estimates for the contributions of selection and dispersal limitation to community assembly, complemented by an examination of spatial clustering of individuals. Phylogenetic and ecological associations of co‐occurrence network module bacteria was determined by assessing the phylogenetic diversity and habitat preferences of member taxa. ResultsDispersal limitation was evident from between‐site variation and spatial aggregation of individual bacterial taxa in theS. purpureapitcher system. Selection pressure was weak across the geographic range, yet network module analysis indicated environmental selection within subgroups. A group of aquatic bacteria held traits under selection in warmer, wetter climates, and midge abundance was associated with selection for traits held by a group of saprotrophs. Processes that increased pitcher fluid volume weakened selection in one module, possibly by supporting greater bacterial dispersal. ConclusionDispersal limitation governed bacterial community assembly inS. purpureapitchers at a continental scale (74% of between‐site comparisons) and was significantly greater than selection across the range. Network modules showed evidence for selection, demonstrating that multiple processes acted concurrently in bacterial community assembly at the continental scale. 

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