Climate change and competition from invasive species remain two important challenges in restoration. We examined the hypothesis that non‐native tamarisk (Tamarix spp.) reestablishment after aboveground removal is affected by genetics‐based architecture of native Fremont cottonwood (Populus fremontii) used in restoration. As cottonwood architecture (height, canopy width, number of stems, and trunk diameter) is, in part, determined by genetics, we predicted that trees from different provenances would exhibit different architecture, and mean annual maximum temperature transfer distance from the provenances would interact with the architecture to affect tamarisk. In a common garden in Chevelon, AZ, U.S.A. (elevation 1,496 m), with cottonwoods from provenances spanning its elevation distribution, we measured the performance of both cottonwoods and tamarisk. Several key findings emerged. On average, cottonwoods from higher elevations were (1) two times taller and wider, covered approximately 3.5 times more basal area, and were less shrubby in appearance, by exhibiting four times fewer number of stems than cottonwoods from lower elevations; (2) had 50% fewer tamarisk growing underneath, which were two times shorter and covered 6.5 times less basal area than tamarisk growing underneath cottonwoods of smaller stature; and (3) the number of cottonwood stems did not affect tamarisk growth, possibly because the negative relationship between cottonwood stems and basal area. In combination, these findings argue that cottonwood architecture is affected by local conditions that interact with genetics‐based architecture. These interactions can negatively affect the growth of reinvading tamarisk and enhance restoration success. Our study emphasizes the importance of incorporating genetic and environmental interactions of plants used in restoration.

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The Heterostraci are a subclass of armored jawless vertebrates that were widespread in marginal marine environments around the Old Red Sandstone continent during the late Silurian to Middle Devonian. Although a number of clades have long been recognized, further analysis has been limited by lack of morphological information beyond that afforded by the armor, thus impeding understanding of early vertebrate evolution. Phylogenetic analysis of several heterostracan clades has been carried out previously and we here show an analysis of the family Cyathaspididae in which we prioritize the feature of a single branchial plate as a defining character of the family and reject a number of taxa previously included in analyses of this taxon. This analysis resolves to a single consensus tree showing that the Cyathaspididae is composed of a series of clades that are congruent with the subfamily groupings erected previously: Tolypelepidinae, Irregulareaspidinae, Poraspidinae, Anglaspidinae, and Boothiaspidinae. A trend can be seen from earlier members of the family with a dorsal shield divided into four epitega or growth areas (Asketaspis, Tolypelepis) to the most derived members (Poraspis, Faberaspis) in which the epitega are lost entirely. In addition, the earliest taxa are shown to have possessed shields composed of scale-like elements, which are lost and replaced by continuous ridges in the more derived members. This result supports the hypothesis that the earliest members of the Heterostraci may also have been scale-covered.

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This report documents the last pteraspids, (armored, jawless members of the Heterostraci), which are otherwise only known from the Early Devonian of the Old Red Sandstone Continent. Tuberculate pteraspid heterostracans are described from the Middle Devonian beds of two formations in western North America. The late Givetian Yahatinda Formation of Alberta and British Columbia consists of channels cut into lower Paleozoic rocks and represents deposition in marine to littoral environments. Clavulaspis finis (Elliott et al., 2000a) new combination is redescribed from additional material from the Yahatinda Formation and reassigned to the new genus Clavulaspis because the original genus name is invalid. The Eifelian Spring Mountain beds of Idaho consist of a large channel that represents a clastic-dominated estuarine environment. It contains Scutellaspis wilsoni new genus new species, and the previously described species from the Spring Mountain beds is redescribed and reassigned to Ecphymaspis new genus, which was prompted by new material and a review of the validity of the original genus name. Phylogenetic analysis shows that these three new taxa form part of the derived clade Protaspididae.UUID: http://zoobank.org/9cf09b21-cec1-4ce4-bc2b-658d0b515e10