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1. Tracing demographic histories through time using ancient DNA in Chilean Fuego-Patagonia

   Balentine, C. M.; Alfonso-Durruty, M.; Reynolds, A. W.; Vilar, M.; Morello, F.; San Román, M.; Springs, L. C.; Bolnick, D. A. (January 2022, American Journal of Biological Anthropology)

   Historically, hunter-gatherers living east and west of the Andean foothills of southern South America (Fuego-Patagonia) practiced different subsistence strategies. To the east, the wide open and relatively dry pampas presented a climate ideal for Terrestrial hunter-gatherers who depended on terrestrial animals (e.g., Lama guanicoe). In contrast, Marine hunter-gatherers who lived on islands in the western archipelago, a colder and wetter environment, mainly subsisted on marine resources (e.g., seals and shellfish). Archaeological evidence dates Terrestrial hunter-gatherers’ presence in Fuego-Patagonia to at least ~10,500 BP, whereas Marine hunter-gatherers’ presence dates to ~6,500 BP and is associated with highly specialized tools that have only been observed in the archaeological record after this time. Genetic analyses of some ancient Fuegian-Patagonians have supported the hypothesis that Marine hunter-gatherers migrated into the region after Terrestrial hunter-gatherers, around 6,500 BP (7,500 calBP), while analyses of other individuals suggest that Marine hunter-gatherers descended from the earlier Terrestrial hunter-gatherer groups. Here, we test these hypotheses by analyzing newly collected genome-wide data from n=46 ancient Chilean Fuegian-Patagonian individuals belonging to Marine, Terrestrial, and Mixed-economy archaeological sites dating to 6,895–304 calBP. We explored basic population structure among these hunter-gatherer groups using PCA and ADMIXTURE. We calculated π, pairwise-FST, and f-statistics, and developed demographic simulations to further examine genetic relationships among the groups. The results of this study shed light on local demographic patterns of ancient southern South American groups, which in turn provides more insight into broader population histories of South America. This study was funded by FONDECYT (Chile), National Geographic Society, National Science Foundation, and Wenner-Gren Foundation. C. M. Balentine is supported by an NSF Graduate Research Fellowship. 

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2. Genomic and transcriptomic survey of bryozoan Hox and ParaHox genes with emphasis on phylactolaemate bryozoans

   https://doi.org/10.1186/s12864-023-09826-z  

   Saadi, Ahmed J; de_Oliveira, André Luiz; Kocot, Kevin M; Schwaha, Thomas (December 2023, BMC Genomics)

   Bryozoans are mostly sessile aquatic colonial invertebrates belonging to the clade Lophotrochozoa, which unites many protostome bilaterian phyla such as molluscs, annelids and brachiopods. While Hox and ParaHox genes have been extensively studied in various lophotrochozoan lineages, investigations on Hox and ParaHox gene complements in bryozoans are scarce. Herein, we present the most comprehensive survey of Hox and ParaHox gene complements in bryozoans using four genomes and 35 transcriptomes representing all bryozoan clades: Cheilostomata, Ctenostomata, Cyclostomata and Phylactolaemata. Using similarity searches, phylogenetic analyses and detailed manual curation, we have identified five Hox genes in bryozoans (pb, Dfd, Lox5, Lox4 and Post2) and one ParaHox gene (Cdx). Interestingly, we observed lineage-specific duplication of certain Hox and ParaHox genes (Dfd, Lox5 and Cdx) in some bryozoan lineages. The bryozoan Hox cluster does not retain the ancestral lophotrochozoan condition but appears relatively simple (includes only five genes) and broken into two genomic regions, characterized by the loss and duplication of serval genes. Importantly, bryozoans share the lack of two Hox genes (Post1 and Scr) with their proposed sister-taxon, Phoronida, which suggests that those genes were missing in the most common ancestor of bryozoans and phoronids. 

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3. A genetically based ecological trade‐off contributes to setting a geographic range limit

   https://doi.org/10.1111/ele.13900  

   Mauro, Alexander A.; Torres‐Dowdall, Julián; Marshall, Craig A.; Ghalambor, Cameron K.; Angert, ed., Amy (October 2021, Ecology Letters)

   Abstract Understanding the ecological factors that shape geographic range limits and the evolutionary constraints that prevent populations from adaptively evolving beyond these limits is an unresolved question. Here, we investigated why the euryhaline fish,Poecila reticulata, is confined to freshwater within its native range, despite being tolerant of brackish water. We hypothesised that competitive interactions with a close relative,Poecilia picta, in brackish water preventsP.reticulatafrom colonising brackish water. Using a combination of field transplant, common garden breeding, and laboratory behaviour experiments, we find support for this hypothesis, asP.reticulataare behaviourally subordinate and have lower survival in brackish water withP.picta. We also found a negative genetic correlation betweenP.reticulatagrowth in brackish water versus freshwater in the presence ofP.picta, suggesting a genetically based trade‐off between salinity tolerance and competitive ability could constrain adaptive evolution at the range limit. 

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4. 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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5. A new vertebrate fauna from the Lower Cretaceous Holly Creek Formation of the Trinity Group, southwest Arkansas, USA

   https://doi.org/10.7717/peerj.12242  

   Suarez, Celina A.; Frederickson, Joseph; Cifelli, Richard L.; Pittman, Jeffrey G.; Nydam, Randall L.; Hunt-Foster, ReBecca K.; Morgan, Kirsty (January 2021, PeerJ)

   We present a previously discovered but undescribed late Early Cretaceous vertebrate fauna from the Holly Creek Formation of the Trinity Group in Arkansas. The site from the ancient Gulf Coast is dominated by semi-aquatic forms and preserves a diverse aquatic, semi-aquatic, and terrestrial fauna. Fishes include fresh- to brackish-water chondrichthyans and a variety of actinopterygians, including semionotids, an amiid, and a new pycnodontiform, Anomoeodus caddoi sp. nov. Semi-aquatic taxa include lissamphibians, the solemydid turtle Naomichelys , a trionychid turtle, and coelognathosuchian crocodyliforms. Among terrestrial forms are several members of Dinosauria and one or more squamates, one of which, Sciroseps pawhuskai gen. et sp. nov., is described herein. Among Dinosauria, both large and small theropods ( Acrocanthosaurus , Deinonychus , and Richardoestesia ) and titanosauriform sauropods are represented; herein we also report the first occurrence of a nodosaurid ankylosaur from the Trinity Group. The fauna of the Holly Creek Formation is similar to other, widely scattered late Early Cretaceous assemblages across North America and suggests the presence of a low-diversity, broadly distributed continental ecosystem of the Early Cretaceous following the Late Jurassic faunal turnover. This low-diversity ecosystem contrasts sharply with the highly diverse ecosystem which emerged by the Cenomanian. The contrast underpins the importance of vicariance as an evolutionary driver brought on by Sevier tectonics and climatic changes, such as rising sea level and formation of the Western Interior Seaway, impacting the early Late Cretaceous ecosystem. 

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