The fossil record and macroevolutionary history of North American ungulate mammals: standardizing variation in intensity and geography of sampling

Paleobiology ◽  
10.1666/13052 ◽  
2014 ◽  
Vol 40 (2) ◽  
pp. 238-255 ◽  
Author(s):  
Jonathan D. Marcot
Keyword(s):  
Convex Hull ◽  
Environmental Change ◽  
Geographic Variation ◽  
North American ◽  
Fossil Record ◽  
Geographic Distance ◽  
Geographic Location ◽  
Pairwise Distance ◽  
Evolutionary Response ◽  
Over Time

The record of the taxonomic evolution of North American ungulates is critical to our understanding of mammalian evolution and environmental change throughout the Cenozoic. The distribution of sampling in the ungulate fossil record over time and geographic space and the degree to which this biases the observed patterns of taxonomic evolution is poorly understood. To address these issues, I placed fossil collections and occurrences drawn from the Paleobiology Database into 2-Myr time intervals between 55 and 1 Ma. I determined the variation in numbers of fossil collections and occurrences, using three metrics to measure geographic variation: first, the area of the convex hull containing all collections in an interval, to determine the areal coverage of sampling; second, the mean pairwise geographic distance among collections as a measurement of the dispersion of collections within that area; and third, the interval-to-interval migration of the geographic centroid of all collections, to calculate changes in the geographic location of sampling. Each of these showed considerable variation over the Cenozoic, and both the area of the convex hull (ACH) encompassing all collections in an interval, and mean pairwise distance (MPWD) among them showed increasing trends over time.To minimize the effect of variation in numbers of fossil samples over time, I used standard sample-standardization procedures. To minimize the effect of geographic variation in sampling over time, I standardized the area of sampling among intervals. I also employed both standardizations sequentially. Each standardization procedure had surprisingly little effect on observed patterns of taxonomic richness and rates. This indicates that, for North American ungulates, neither variation in number nor geographic distribution of fossil samples exerts an overwhelming influence on perceived macroevolutionary patterns. These results confirm the ungulate fossil record as a critical and faithful record for our understanding of Cenozoic environmental change and the mammalian evolutionary response.

Spatiotemporal palaeodiversity patterns of modern crocodiles (Crocodyliformes: Eusuchia)

2019 ◽  
Vol 189 (2) ◽  
pp. 635-656 ◽  
Author(s):  
Ane De Celis ◽  
Iván Narváez ◽  
Francisco Ortega
Keyword(s):  
South America ◽  
Least Squares ◽  
Late Miocene ◽  
North American ◽  
Fossil Record ◽  
Generalized Least Squares ◽  
Global Scale ◽  
Biotic Factors ◽  
Species Dynamics ◽  
Over Time

Abstract Eusuchia is a crocodyliform clade with a rich and diverse fossil record dating back to the Mesozoic. There are several recent studies that analyse crocodyliform palaeodiversity over time, but none of them focuses exclusively on eusuchians. Thus, we estimated subsampled eusuchian palaeodiversity species dynamics over time not only at a global scale, but also by continents and main crocodylian lineages (Alligatoroidea, Crocodyloidea and Gavialoidea). These estimates reveal complex spatiotemporal palaeodiversity patterns, in which two maxima can be detected: the first during the Palaeocene and the second, which is also the biggest, in the middle-late Miocene. The Palaeocene shift is related to a North American alligatoroid diversification, whereas the middle–late Miocene maximum is related to a diversification of the three main Crocodylia lineages in Gondwanan land masses, but especially in South America. Additionally, a model-based study using generalized least squares was carried out to analyse the relationships between different abiotic and sampling proxies and eusuchian palaeodiversity. The results show that palaeotemperature is the most important factor amongst the analysed proxies, in accordance with previous studies. However, the results suggest that, along with palaeotemperature, other abiotic and/or biotic factors might also be driving eusuchian palaeodiversity dynamics.

Patterns of geographic variation in the skull of Nearctic Ermine (Mustela erminea)

1990 ◽  
Vol 68 (6) ◽  
pp. 1241-1249 ◽  
Author(s):  
Judith L. Eger
Keyword(s):  
Geographic Variation ◽  
North American ◽  
Geographic Distance ◽  
Glacial Refugia ◽  
Clinal Variation ◽  
Shape Variation ◽  
Mustela Erminea ◽  
Temperature And Precipitation ◽  
Glacial Stage ◽  
Species Groups

A. H. Macpherson suggested that much of the current geographic diversity in species and species groups of arctic mammals resulted from isolation in glacial refugia during the Wisconsin glacial stage. The present study evaluates this refugium hypothesis using a statistical assessment of geographic variation in 13 craniometric characters of Nearctic Mustela erminea. There is significant geographic variation among samples of North American ermine. Most of the skull character variance in this species reflects differences in size and is clinal. Variation in skull size is better explained by temperature and precipitation variables than by geographic distance, suggesting that environmentally ordered selection for size has been superimposed on any size differentiation that occurred during isolation in refugia. Variation in skull shape shows a relatively low correlation with climatic variables, and partitioning tests on shape variation reveal discontinuities consistent with the refugium hypothesis. Distinctive groups of samples reflect possible refugial populations in Eastern Beringia, in periglacial refugia south of the Wisconsin ice in eastern North America, and in one or more western North American refugia.

Phylogeography of moose in western North America

2019 ◽  
Vol 101 (1) ◽  
pp. 10-23 ◽  
Author(s):  
Nicholas J DeCesare ◽  
Byron V Weckworth ◽  
Kristine L Pilgrim ◽  
Andrew B D Walker ◽  
Eric J Bergman ◽  
...  
Keyword(s):  
North America ◽  
North American ◽  
Fossil Record ◽  
Complete Mitochondrial Genome ◽  
Geographic Distance ◽  
Ice Age ◽  
Western North America ◽  
Base Pairs ◽  
Phenotype Data ◽  
Continental Glaciation

Abstract Subspecies designations within temperate species’ ranges often reflect populations that were isolated by past continental glaciation, and glacial vicariance is believed to be a primary mechanism behind the diversification of several subspecies of North American cervids. We used genetics and the fossil record to study the phylogeography of three moose subspecies (Alces alces andersoni, A. a. gigas, and A. a. shirasi) in western North America. We sequenced the complete mitochondrial genome (16,341 base pairs; n = 60 moose) and genotyped 13 nuclear microsatellites (n = 253) to evaluate genetic variation among moose samples. We also reviewed the fossil record for detections of all North American cervids to comparatively assess the evidence for the existence of a southern refugial population of moose corresponding to A. a. shirasi during the last glacial maximum of the Pleistocene. Analysis of mtDNA molecular variance did not support distinct clades of moose corresponding to currently recognized subspecies, and mitogenomic haplotype phylogenies did not consistently distinguish individuals according to subspecies groupings. Analysis of population structure using microsatellite loci showed support for two to five clusters of moose, including the consistent distinction of a southern group of moose within the range of A. a. shirasi. We hypothesize that these microsatellite results reflect recent, not deep, divergence and may be confounded by a significant effect of geographic distance on gene flow across the region. Review of the fossil record showed no evidence of moose south of the Wisconsin ice age glaciers ≥ 15,000 years ago. We encourage the integration of our results with complementary analyses of phenotype data, such as morphometrics, originally used to delineate moose subspecies, for further evaluation of subspecies designations for North American moose.

Clinal geographic variation in mammals: implications for the study of chronoclines

Paleobiology ◽  
1986 ◽  
Vol 12 (3) ◽  
pp. 269-281 ◽  
Author(s):  
Paul L. Koch
Keyword(s):  
Body Size ◽  
Geographic Variation ◽  
North American ◽  
Fossil Record ◽  
Mammalian Species ◽  
Didelphis Virginiana ◽  
Mean Annual Temperature ◽  
Sciurus Carolinensis ◽  
Size Change ◽  
Mammalian Fossil

Mammalian species often exhibit clinal geographic variation in body size: individuals tend to be larger in areas with lower mean annual temperature. Climatic change involving increasing or decreasing mean annual temperature may cause clines to shift geographically, resulting in a phenotypic shift at all affected locales within a species' range. I assess the potential of shifting geographic clines to produce morphological trends in the fossil record. Five extant North American mammalian species (Didelphis virginiana, Mephitis mephitis, Odocoileus virginianus, Scalopus aquaticus, and Sciurus carolinensis) are examined to quantify size change along latitudinal clines and to estimate the geographic range and temperature difference commonly associated with a given difference in body size. Relative to body size, the observed size range of skeletal characters within each of these five species is comparable to that seen in a much larger sample of North American mammals. Thus patterns of variation documented for the five species may be used to assess the likelihood of dine translocation as an explanation of size change in the mammalian fossil record. As a case study, I examine three lineages from the Early Eocene of the Bighorn Basin, Wyoming. I determine that size change in these chronoclines represents evolutionary change and is not merely the result of shifting geographic clines.

Social Change and Psychological Change in Rural Mali

2016 ◽  
Vol 52 (7) ◽  
pp. 965-981 ◽  
Author(s):  
Carmi Schooler ◽  
Leslie J Caplan ◽  
Pakuy Pierre Mounkoro ◽  
Chiaka Diakité
Keyword(s):  
Social Change ◽  
Environmental Change ◽  
Environmental Conditions ◽  
Economic Hardship ◽  
Psychological Change ◽  
Self Confidence ◽  
Personality Stability ◽  
Psychological Reaction ◽  
Using Data ◽  
Over Time

We examine the effects of socio-environmental change on personality in Mali in three ways, using data from a longitudinal two-wave (1994, 2004) survey conducted in rural Mali. Firstly, we compare the between-wave personality stability of Anxiety, Self-confidence, Mastery/Fatalism, and Authoritarianism with that in USA, Japan, Poland, and Ukraine. Secondly, we examine socio-economic hardship and political instability in pre-industrial Mali. Thirdly, we examine patterns of psychological reaction to political and social change during the study period. Our findings have implications for comparisons and generalizations across times and cultures about the contribution of socio-environmental conditions to over-time change in personality.

scholarly journals The fossil record of whip spiders: the past of Amblypygi

PalZ ◽  
2021 ◽  
Author(s):  
Carolin Haug ◽  
Joachim T. Haug
Keyword(s):  
Fossil Record ◽  
3D Imaging ◽  
Three Dimensional ◽  
Dorsal Shield ◽  
Stereo Images ◽  
Geological Time ◽  
High Quality ◽  
The Past ◽  
Over Time

AbstractWhip spiders (Amblypygi), as their name suggests, resemble spiders (Araneae) in some aspects, but differ from them by their heart-shaped (prosomal) dorsal shield, their prominent grasping pedipalps, and their subsequent elongate pair of feeler appendages. The oldest possible occurrences of whip spiders, represented by cuticle fragments, date back to the Devonian (c. 385 mya), but (almost) complete fossils are known from the Carboniferous (c. 300 mya) onwards. The fossils include specimens preserved on slabs or in nodules (Carboniferous, Cretaceous) as well as specimens preserved in amber (Cretaceous, Eocene, Miocene). We review here all fossil whip spider specimens, figure most of them as interpretative drawings or with high-quality photographs including 3D imaging (stereo images) to make the three-dimensional relief of the specimens visible. Furthermore, we amend the list by two new specimens (resulting in 37 in total). The fossil specimens as well as modern whip spiders were measured to analyse possible changes in morphology over time. In general, the shield appears to have become relatively broader and the pedipalps and walking appendages have become more elongate over geological time. The morphological details are discussed in an evolutionary framework and in comparison with results from earlier studies.

scholarly journals The effects of geographic range size and abundance on extinction during a time of “sluggish”’ evolution

Paleobiology ◽  
2020 ◽  
pp. 1-14
Author(s):  
Michelle M. Casey ◽  
Erin E. Saupe ◽  
Bruce S. Lieberman
Keyword(s):  
North American ◽  
Fossil Record ◽  
Extinction Risk ◽  
Geographic Range ◽  
Range Size ◽  
Late Paleozoic ◽  
The North ◽  
Geographic Range Size ◽  
The Relationship ◽  
Habitat Tracking

Abstract Geographic range size and abundance are important determinants of extinction risk in fossil and extant taxa. However, the relationship between these variables and extinction risk has not been tested extensively during evolutionarily “quiescent” times of low extinction and speciation in the fossil record. Here we examine the influence of geographic range size and abundance on extinction risk during the late Paleozoic (Mississippian–Permian), a time of “sluggish” evolution when global rates of origination and extinction were roughly half those of other Paleozoic intervals. Analyses used spatiotemporal occurrences for 164 brachiopod species from the North American midcontinent. We found abundance to be a better predictor of extinction risk than measures of geographic range size. Moreover, species exhibited reductions in abundance before their extinction but did not display contractions in geographic range size. The weak relationship between geographic range size and extinction in this time and place may reflect the relative preponderance of larger-ranged taxa combined with the physiographic conditions of the region that allowed for easy habitat tracking that dampened both extinction and speciation. These conditions led to a prolonged period (19–25 Myr) during which standard macroevolutionary rules did not apply.

scholarly journals European Banking Network in Light of the Single Supervisory Mechanism from the Network Analysis Perspective

2015 ◽  
Vol 6 (1) ◽  
pp. 35-57 ◽  
Author(s):  
Mária Širaňová
Keyword(s):  
Network Analysis ◽  
Financial Stability ◽  
Geographic Distance ◽  
Topological Properties ◽  
Economic Space ◽  
Single Supervisory Mechanism ◽  
Cross Border ◽  
European Banking ◽  
Positive Step ◽  
Over Time

In this paper we discuss the topological properties of the European banking network and its evolution over time based on the BIS consolidated banking statistics data exploiting information from complex network analysis. Our conclusions are discussed in light of the soon-to-be-launched Single Supervisory Mechanism that takes into account, among other things, the significance of cross-border activity as a precondition for specifying the systemically important European credit institutions. According to our results, the banking network of the EU13 economic space can be characterized as highly asymmetric with a tendency to create clusters based on geographic distance and cultural and social similarities. Additionally, the highly exposed countries are usually dependent on a small number of major creditors while creditor countries tend to spread their power over dependent countries more equally. We advocate that the presence of heterogeneity and asymmetry in the network and a decrease in the level of foreign banking across Europe could be mitigated by the introduction of SSM, and from this perspective it should be viewed as a positive step towards greater financial stability.

scholarly journals Mutation load dynamics during environmentally-driven range shifts

2018 ◽  
Author(s):  
Kimberly J. Gilbert ◽  
Stephan Peischl ◽  
Laurent Excoffier
Keyword(s):  
Environmental Change ◽  
Geographic Distance ◽  
Species Range ◽  
Range Shifts ◽  
Strong Impact ◽  
Generalist Species ◽  
Deleterious Alleles ◽  
Species Survival ◽  
Specialist Species ◽  
The Impact

AbstractThe fitness of spatially expanding species has been shown to decrease over time and space, but specialist species tracking their changing environment and shifting their range accordingly have been little studied. We use individual-based simulations and analytical modeling to compare the impact of range expansions and range shifts on genetic diversity and fitness loss, as well as the ability to recover fitness after either a shift or expansion. We find that the speed of a shift has a strong impact on fitness evolution. Fastest shifts show the strongest fitness loss per generation, but intermediate shift speeds lead to the strongest fitness loss per geographic distance. Range shifting species lose fitness more slowly through time than expanding species, however, their fitness compared at equivalent geographic distances spread can be considerably lower. These counter-intuitive results arise from the combination of time over which selection acts and mutations enter the system. Range shifts also exhibit reduced fitness recovery after a geographic shift and may result in extinction, whereas range expansions can persist from the core of the species range. The complexity of range expansions and range shifts highlights the potential for severe consequences of environmental change on species survival.Author SummaryAs environments change through time across the globe, species must adapt or relocate to survive. Specialized species must track the specific moving environments to which they are adapted, as compared to generalists which can spread widely. During colonization of new habitat, individuals can accumulate deleterious alleles through repeated bottlenecks. We show through simulation and analytic modeling that the process by which these alleles accumulate changes depending upon the speed at which populations spread over a landscape. This is due to the increased efficacy of selection against deleterious variants at slow speeds of range shifts and decreased input of mutations at faster speeds of range shifts. Under some selective circumstances, shifting of a species range leads to extinction of the entire population. This suggests that the rate of environmental change across the globe will play a large role in the survival of specialist species as compared to more generalist species.

scholarly journals Evidence for continent-wide convergent evolution and stasis throughout 150 years of a biological invasion

2021 ◽  
Author(s):  
Yihan Wu ◽  
Robert I Colautti
Keyword(s):  
Adaptive Evolution ◽  
Fossil Record ◽  
Field Experiments ◽  
Common Garden ◽  
Lythrum Salicaria ◽  
Natural Systems ◽  
Continental Scale ◽  
Evolutionary Response ◽  
Temperature Records ◽  
Growing Conditions

The extent to which evolution can rescue a species from extinction, or facilitate range expansion, depends critically on the rate, duration, and geographical extent of the evolutionary response to natural selection. While field experiments have demonstrated that adaptive evolution can occur quickly, our understanding of the duration and geographical extent of contemporary evolution in natural systems remains limited. This is particularly true for species with large geographical ranges and for timescales that lie between 'long-term' field experiments and the fossil record. Here, we introduce the Virtual Common Garden (VCG) to estimate genetic differences among phenotypes observed in natural history collections. Reconstructing 150 years of evolution in Lythrum salicaria (purple loosestrife) as it invaded across North America, we analyze phenology measurements of 3,429 herbarium records, reconstruct growing conditions from more than 12 million local temperature records, and validate predictions across three common gardens spanning 10 degrees of latitude. We find that phenology evolves rapidly and repeatedly along parallel climatic gradients during the first century of evolution. However, the rate of microevolution stalls thereafter, recapitulating macroevolutionary stasis observed in the fossil record. Our study demonstrates why preserved specimens are a critical resource for understanding limits to evolution in natural. Our results show predictability of evolution emerging at a continental scale across 15 decades of rapid, adaptive evolution.

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