Postcranial diversity and recent ecomorphic impoverishment of North American gray wolves

An update on Aenocyon dirus in the interior of North America: new records, radiocarbon dates, ZooMS spectra, and isotopic data for an iconic late Pleistocene carnivore

Aenocyon dirus played a crucial role as a predator in late Quaternary megafaunal communities throughout southern North America. This article presents two new occurrences of the species from southwest Iowa on the eastern Great Plains, updates the Peccary Cave record in the southern Ozark Highlands, and amends the fossil record of the species. In southern North America, there are 166 occurrences of A. dirus, spanning Marine Isotope Stage (MIS) 2-19, with at least two-thirds (n = 112) of the occurrences dating to MIS 2-3 (11,600-57,000 cal B.P.). A. dirus fossils are found across this region, with notable concentrations in California, Florida, the Ozark Highlands, and broadly across the southern Great Plains. Consideration of Canis specimens from the lead region (covering contiguous parts of Illinois, Wisconsin, and Iowa) previously identified as Canis mississippiensis (and sometimes synonymized with A. dirus or C. lupus) reveals they are actually C. lupus. The terminal extinction of A. dirus occurred sometime after 12,800 cal B.P. The Iowa finds, consisting of a radius and a partial cranium, are the first records for the state. Zooarchaeology by mass spectrometry confirms these records, as well as the Peccary Cave record, are A. dirus, as opposed to C. lupus. The Iowa specimens are directly dated to 29,040-28,410 cal B.P. and 14,325-14,075 cal B.P., while Peccary Cave is dated to 25,350-21,405 cal B.P. These results place A. dirus in the interior of southern North America before, during, and after the Last Glacial Maximum (26,500-19,000 cal B.P.). Stable nitrogen isotope (δ15N) values of bone collagen from the younger of the two Iowa records suggest this individual did not regularly compete for prey with Smilodon fatalis during the Bølling-Allerød Chronozone (14,640-12,850 cal B.P.). To the south, at Peccary Cave, considerations of prey size, prey abundance, and isotopic data strongly suggest Platygonus compressus was the focal prey species.

What does it mean to be wild? Assessing human influence on the environments of nonhuman primate specimens in museum collections

OBJECTIVES

Natural history collections are often thought to represent environments in a pristine natural state-free from human intervention-the so-called "wild." In this study, we aim to assess the level of human influence represented by natural history collections of wild-collected primates over 120 years at the Smithsonian Institution's National Museum of Natural History (NMNH).

MATERIALS AND METHODS

Our sample consisted of 875 catarrhine primate specimens in NMNH collections, representing 13 genera collected in 39 countries from 1882 to 2004. Using archival and accession information we determined the approximate locations from which specimens were collected. We then plotted location coordinates onto publicly available anthrome maps created by Ellis et al. (Global Ecology and Biogeography, 2010, 19, 589), which delineate terrestrial biomes of human population density and land use worldwide since the 1700s.

RESULTS

We found that among primates collected from their native ranges, 92% were from an environment that had some level of human impact, suggesting that the majority of presumed wild-collected primate specimens lived in an environment influenced by humans during their lifetimes.

DISCUSSION

The degree to which human-modified environments may have impacted the lives of primates currently held in museum collections has been historically ignored, implicating unforeseen consequences for collection-based research. While unique effects related to commensalism with humans remain understudied, effects currently attributed to natural phenomena may, in fact, be related to anthropogenic pressures on unmanaged populations of primates.

Considering Pleistocene North American wolves and coyotes in the eastern Canis origin story

The evolutionary origins and hybridization patterns of Canis species in North America have been hotly debated for the past 30 years. Disentangling ancestry and timing of hybridization in Great Lakes wolves, eastern Canadian wolves, red wolves, and eastern coyotes are most often partitioned into a 2-species model that assigns all ancestry to gray wolves and/or coyotes, and a 3-species model that includes a third, North American evolved eastern wolf genome. The proposed models address recent or sometimes late Holocene hybridization events but have largely ignored potential Pleistocene era progenitors and opportunities for hybridization that may have impacted the current mixed genomes in eastern Canada and the United States. Here, we re-analyze contemporary and ancient mitochondrial DNA genomes with Bayesian phylogenetic analyses to more accurately estimate divergence dates among lineages. We combine that with a review of the literature on Late Pleistocene Canis distributions to: (a) identify potential Pleistocene progenitors to southern North American gray wolves and eastern wolves; and (b) illuminate opportunities for ancient hybridization events. Specifically, we propose that Beringian gray wolves (C. lupus) and extinct large wolf-like coyotes (C. latrans orcutti) are likely progenitors to Mexican and Plains gray wolves and eastern wolves, respectively, and may represent a potentially unrecognized source of introgressed genomic variation within contemporary Canis genomes. These events speak to the potential origins of contemporary genomes and provide a new perspective on Canis ancestry, but do not negate current conservation priorities of dwindling wolf populations with unique genomic signatures and key ecologically critical roles.

Insect morphometry is reproducible under average investigation standards

Morphometric research is being applied to a growing number and variety of organisms. Discoveries achieved via morphometric approaches are often considered highly transferable, in contrast to the tacit and idiosyncratic interpretation of discrete character states. The reliability of morphometric workflows in insect systematics has never been a subject of focused research, but such studies are sorely needed. In this paper, we assess the reproducibility of morphometric studies of ants where the mode of data collection is a shared routine.We compared datasets generated by eleven independent gaugers, that is, collaborators, who measured 21 continuous morphometric traits on the same pool of individuals according to the same protocol. The gaugers possessed a wide range of morphometric skills, had varying expertise among insect groups, and differed in their facility with measuring equipment. We used intraclass correlation coefficients (ICC) to calculate repeatability and reproducibility values (i.e., intra- and intergauger agreements), and we performed a multivariate permutational multivariate analysis of variance (PERMANOVA) using the Morosita index of dissimilarity with 9,999 iterations.The calculated average measure of intraclass correlation coefficients of different gaugers ranged from R = 0.784 to R = 0.9897 and a significant correlation was found between the repeatability and the morphometric skills of gaugers (p = 0.016). There was no significant association with the magnification of the equipment in the case of these rather small ants. The intergauger agreement, that is the reproducibility, varied between R = 0.872 and R = 0.471 (mean R = 0.690), but all gaugers arrived at the same two-species conclusion. A PERMANOVA test revealed no significant gauger effect on species identity (R 2 = 0.69, p = 0.58).Our findings show that morphometric studies are reproducible when observers follow the standard protocol; hence, morphometric findings are widely transferable and will remain a valuable data source for alpha taxonomy.

Postcranial diversity and recent ecomorphic impoverishment of North American gray wolves

Recent advances in genomics and palaeontology have begun to unravel the complex evolutionary history of the gray wolf, Canis lupus Still, much of their phenotypic variation across time and space remains to be documented. We examined the limb morphology of the fossil and modern North American gray wolves from the late Quaternary (<ca 70 ka) to better understand their postcranial diversity through time. We found that the late-Pleistocene gray wolves were characterized by short-leggedness on both sides of the Cordilleran-Laurentide ice sheets, and that this trait survived well into the Holocene despite the collapse of Pleistocene megafauna and disappearance of the 'Beringian wolf' from Alaska. By contrast, extant populations in the Midwestern USA and northwestern North America are distinguished by their elongate limbs with long distal segments, which appear to have evolved during the Holocene possibly in response to a new level or type of prey depletion. One of the consequences of recent extirpation of the Plains (Canis lupus nubilus) and Mexican wolves (C. l. baileyi) from much of the USA is an unprecedented loss of postcranial diversity through removal of short-legged forms. Conservation of these wolves is thus critical to restoration of the ecophenotypic diversity and evolutionary potential of gray wolves in North America.