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Articles 1 - 19 of 19
Full-Text Articles in Life Sciences
Genetic Admixture In Multidimensional Niche Space: Asymmetrical Niche Similarity Promotes Gene Flow In Armadillos (Dasypus Novemcinctus), Maria Arteaga, John Mccormack, Luis Eguiarte, Rodrigo Medellín
Genetic Admixture In Multidimensional Niche Space: Asymmetrical Niche Similarity Promotes Gene Flow In Armadillos (Dasypus Novemcinctus), Maria Arteaga, John Mccormack, Luis Eguiarte, Rodrigo Medellín
John E. McCormack
We unite genetic data with a robust test of niche divergence to test the hypothesis that patterns of gene flow between two lineages of the nine-banded armadillo are influenced by their climatic niches. We collected Geographical Information System (GIS) data on climate using locality information from 111 individuals from two lineages that had associated genetic material. We tested whether niches of these lineages were more conserved or divergent than the background environments of their geographic ranges and found evidence for niche conservatism on two axes and no evidence for divergence on any axis. To address the role of niche similarity …
New Phylogenetic Information Suggests Both An Increase And At Least One Loss Of Cooperative Breeding During The Evolutionary History Of Aphelocoma Jays, Elena Berg, Robert Aldredge, A. Peterson, John Mccormack
New Phylogenetic Information Suggests Both An Increase And At Least One Loss Of Cooperative Breeding During The Evolutionary History Of Aphelocoma Jays, Elena Berg, Robert Aldredge, A. Peterson, John Mccormack
John E. McCormack
Efforts to identify ecological and life history factors associated with cooperative breeding have been largely unsuccessful, and interest is growing in the role of phylogenetic history in determining the distribution of this social system among lineages. In birds, cooperative breeding is distributed non-randomly among lineages, suggesting that phylogenetic inertia may play an important role in determining its distribution. The bird genus Aphelocoma has been particularly well studied because, although it is a relatively small genus, it shows broad among-lineage variation in level of cooperation. Previous analyses described an unusual unidirectional pattern of evolutionary loss of cooperation in Aphelocoma. Here, historical …
Calibrating Divergence Times On Species Tree Versus Gene Trees: Implications For Speciation History Of Aphelocoma Jays, John Mccormack, Joseph Heled, Kathleen Delaney, A. Peterson, L. Knowles
Calibrating Divergence Times On Species Tree Versus Gene Trees: Implications For Speciation History Of Aphelocoma Jays, John Mccormack, Joseph Heled, Kathleen Delaney, A. Peterson, L. Knowles
John E. McCormack
Estimates of the timing of divergence are central to testing the underlying causes of speciation. Relaxed molecular clocks and fossil calibration have improved these estimates; however, these advances are implemented in the context of gene trees, which can overestimate divergence times. Here we couple recent innovations for dating speciation events with the analytical power of species trees, where multilocus data are considered in a coalescent context. Divergence times are estimated in the bird genus Aphelocoma to test whether speciation in these jays coincided with mountain uplift or glacial cycles. Gene trees and species trees show general agreement that diversification began …
Does Niche Divergence Accompany Allopatric Divergence In Aphelocoma Jays As Predicted Under Ecological Speciation?: Insights From Tests With Niche Models, John Mccormack, Amanda Zellmer, L. Knowles
Does Niche Divergence Accompany Allopatric Divergence In Aphelocoma Jays As Predicted Under Ecological Speciation?: Insights From Tests With Niche Models, John Mccormack, Amanda Zellmer, L. Knowles
John E. McCormack
The role of ecology in the origin of species has been the subject of long-standing interest to evolutionary biologists. New sources of spatially explicit ecological data allow for large-scale tests of whether speciation is associated with niche divergence or whether closely related species tend to be similar ecologically (niche conservatism). Because of the confounding effects of spatial autocorrelation of environmental variables, we generate null expectations for niche divergence for both an ecological-niche modeling and a multivariate approach to address the question: do allopatrically distributed taxa occupy similar niches? In a classic system for the study of niche evolution—the Aphelocoma jays—we …
The Delimitation Of Flammulina Fennae, Soňa Ripková, Karen Hughes, Slavomír Adamčík, Viktor Kučera, Katarína Adamčíková
The Delimitation Of Flammulina Fennae, Soňa Ripková, Karen Hughes, Slavomír Adamčík, Viktor Kučera, Katarína Adamčíková
Karen Hughes
Multivariate morphometric analyses of micromorphological characters measured on 35 specimens of Flammulina fennae and related species show that only a combination of spore dimensions and ixohyphidia characters are suitable for delimitation of this species. In order to confirm species identifications based on micromorphology, ribosomal ITS DNA sequences were obtained and compared with those previously deposited in GenBank, and phylogenetic analyses were performed using an ITS dataset of all known Flammulina species. All six specimens morphologically determined as F. fennae were identified by molecular data. Two of twelve specimens morphologically assigned to F. velutipes had F. elastica sequences. One ITS sequence …
A New Genus To Accommodate Gymnopus Acervatus (Agaricales), Karen Hughes, David A. Mather, Ronald H. Peterson
A New Genus To Accommodate Gymnopus Acervatus (Agaricales), Karen Hughes, David A. Mather, Ronald H. Peterson
Karen Hughes
Phylogenies based on ITS and LSU nrDNA sequences show Agaricus (Gymnopus) acervatus as unique within the Gymnopus/Rhodocollybia complex. These phylogenies imply that a separate genus is necessary, and Connopus is proposed. Infraspecific morphological and DNA-based variation within C. acervatus suggests that a western North American clade might be reproductively isolated from the eastern North American/Scandinavian clade and that in this species complex the European and eastern North American clade might be conspecific. A Scandinavian exemplar is selected for bar-coding. Two GenBank sequences with name-phylogenetic placement inconsistencies are identified.
Small-Scale Divergence In Egg Color Along An Elevation Gradient In The Mexican Jay (Aphelocoma Ultramarina): A Condition-Dependent Response?, John Mccormack, Elena Berg
Small-Scale Divergence In Egg Color Along An Elevation Gradient In The Mexican Jay (Aphelocoma Ultramarina): A Condition-Dependent Response?, John Mccormack, Elena Berg
John E. McCormack
The functional significance of bird egg color and patterning is a continuing subject of interest and debate. Extreme polymorphism in eggshell appearance is often thought to be maintained by frequency-dependent selection operating within populations. However, variation could also be explained by small-scale differentiation combined with limited migration. Here, we report the existence of extreme variation in egg color in a population of Mexican Jays (Aphelocoma ultramarina) inhabiting a steep elevation and habitat gradient within a single mountain range, the Sierra del Carmen of Coahuila, Mexico. We quantified egg color of 143 eggs from 54 nests throughout the mountain range, using …
Maximum Likelihood Estimates Of Species Trees: How Accuracy Of Phylogenetic Inference Depends Upon The Divergence History And Sampling Design, John Mccormack, Huateng Huang, L. Knowles
Maximum Likelihood Estimates Of Species Trees: How Accuracy Of Phylogenetic Inference Depends Upon The Divergence History And Sampling Design, John Mccormack, Huateng Huang, L. Knowles
John E. McCormack
The understanding that gene trees are often in discord with each other and with the species trees that contain them has led researchers to methods that incorporate the inherent stochasticity of genetic processes in the phylogenetic estimation procedure. Recently developed methods for species-tree estimation that not only consider the retention and sorting of ancestral polymorphism but also quantify the actual probabilities of incomplete lineage sorting are expected to provide an improvement over earlier summary-statistic based approaches that discard much of the information content of gene trees. However, these new methods have yet to be tested on truly challenging evolutionary histories …
Landscape Genetics Of California Mule Deer (Odocoileus Hemionus): The Roles Of Ecological And Historical Factors In Generating Differentiation, Katherine Pease, Adam Freedman, John Pollinger, John Mccormack, Wolfgang Buermann, Jeff Rodzen, Jim Banks, Erin Meredith, Vernon Bleich, Robert Schaefer, Ken Jones, Robert Wayne
Landscape Genetics Of California Mule Deer (Odocoileus Hemionus): The Roles Of Ecological And Historical Factors In Generating Differentiation, Katherine Pease, Adam Freedman, John Pollinger, John Mccormack, Wolfgang Buermann, Jeff Rodzen, Jim Banks, Erin Meredith, Vernon Bleich, Robert Schaefer, Ken Jones, Robert Wayne
John E. McCormack
Landscape genetics is an emerging discipline that utilizes environmental and historical data to understand geographic patterns of genetic diversity. Niche modelling has added a new dimension to such efforts by allowing species–environmental associations to be projected into the past so that hypotheses about historical vicariance can be generated and tested independently with genetic data. However, previous approaches have primarily utilized DNA sequence data to test inferences about historical isolation and may have missed very recent episodes of environmentally mediated divergence. We type 15 microsatellite loci in California mule deer and identify five genetic groupings through a Structure analysis that are …
Sky Islands, John Mccormack, Huateng Huang, L. Knowles
Sky Islands, John Mccormack, Huateng Huang, L. Knowles
John E. McCormack
No abstract provided.
Mexican Jay (Aphelocoma Ultramarina), John Mccormack, L. Brown
Mexican Jay (Aphelocoma Ultramarina), John Mccormack, L. Brown
John E. McCormack
No abstract provided.
Niche Expansion Leads To Small-Scale Adaptive Divergence Along An Elevation Gradient In A Medium-Sized Passerine Bird, John Mccormack, Thomas Smith
Niche Expansion Leads To Small-Scale Adaptive Divergence Along An Elevation Gradient In A Medium-Sized Passerine Bird, John Mccormack, Thomas Smith
John E. McCormack
Niche expansion can lead to adaptive differentiation and speciation, but there are few examples from contemporary niche expansions about how this process is initiated. We assess the consequences of a niche expansion by Mexican jays (Aphelocoma ultramarina) along an elevation gradient. We predicted that jays at high elevation would have straighter bills adapted to feeding on pine cones, whereas jays at low elevation would have hooked bills adapted to feeding on acorns. We measured morphological and genetic variation of 95 adult jays and found significant differences in hook length between elevations in accordance with predictions, a pattern corroborated by analysis …
Integrating Paleoecology And Genetics Of Bird Populations In Two Sky Island Archipelagos, John Mccormack, Bonnie Bowen, Thomas Smith
Integrating Paleoecology And Genetics Of Bird Populations In Two Sky Island Archipelagos, John Mccormack, Bonnie Bowen, Thomas Smith
John E. McCormack
Background: Genetic tests of paleoecological hypotheses have been rare, partly because recent genetic divergence is difficult to detect and time. According to fossil plant data, continuous woodland in the southwestern USA and northern Mexico became fragmented during the last 10,000 years, as warming caused cool-adapted species to retreat to high elevations. Most genetic studies of resulting 'sky islands' have either failed to detect recent divergence or have found discordant evidence for ancient divergence. We test this paleoecological hypothesis for the region with intraspecific mitochondrial DNA and microsatellite data from sky-island populations of a sedentary bird, the Mexican jay (Aphelocoma ultramarina). …
Speciation In The Highlands Of Mexico: Genetic And Phenotypic Divergence In The Mexican Jay (Aphelocoma Ultramarina), John Mccormack, A. Peterson, E. Bonaccorso, Thomas Smith
Speciation In The Highlands Of Mexico: Genetic And Phenotypic Divergence In The Mexican Jay (Aphelocoma Ultramarina), John Mccormack, A. Peterson, E. Bonaccorso, Thomas Smith
John E. McCormack
The pine-oak woodlands of the Mexican highlands harbour significant biological diversity, yet little is known about the evolutionary history of organisms inhabiting this region. We assessed genetic and phenotypic differentiation in 482 individuals representing 27 populations of the Mexican jay (Aphelocoma ultramarina) — a widespread bird species of the Mexican highlands — to test whether populations in the central and northern Mexican sierras display discrete breaks between groups, which would be consistent with a role for the different mountain chains in divergence and speciation. We found abrupt breaks in mitochondrial DNA (mtDNA; ND2 and control region) delineating four major genetic …
Producer-Scrounger Roles And Joining Based On Dominance In A Free-Living Group Of Mexican Jays (Aphelocoma Ultramarina), John Mccormack, Piotr Jablonski, Jerram Brown
Producer-Scrounger Roles And Joining Based On Dominance In A Free-Living Group Of Mexican Jays (Aphelocoma Ultramarina), John Mccormack, Piotr Jablonski, Jerram Brown
John E. McCormack
While foraging, animals often exploit group members to obtain food. One way to describe this behaviour is with the producer-scrounger (PS) model, where scroungers use social interaction to obtain food discovered by producers. Mexican jays (Aphelocoma ultramarina) are a groupforaging species with a linear dominance hierarchy. We studied interactions in a free-living foraging group to determine (1) if foraging interactions can be explained with the PS model, (2) if these roles are consistent and (3) if dominance or relatedness affects joining frequency. We recorded board-flipping, eating, and joining events during sets of feeding trials. We show that Mexican jays use …
Recent Postglacial Range Expansion Drives The Rapid Diversification Of A Songbird Lineage In The Genus Junco, Borja Milá, John Mccormack, Gabriela Castañeda, Robert Wayne, Thomas Smith
Recent Postglacial Range Expansion Drives The Rapid Diversification Of A Songbird Lineage In The Genus Junco, Borja Milá, John Mccormack, Gabriela Castañeda, Robert Wayne, Thomas Smith
John E. McCormack
Pleistocene glacial cycles are thought to have played a major role in the diversification of temperate and boreal species of North American birds. Given that coalescence times between sister taxa typically range from 0.1 to 2.0 Myr, it has been assumed that diversification occurred as populations were isolated in refugia over long periods of time, probably spanning one to several full glacial cycles. In contrast, the rapid postglacial range expansions and recolonization of northern latitudes following glacial maxima have received less attention as potential promoters of speciation. Here we report a case of extremely rapid diversification in the songbird genus …
Sierra Santa Rosa: An Oasis Of Bird Diversity In Arid Northern Mexico, John Mccormack, Gabriela Castañeda, Greg Levandoski
Sierra Santa Rosa: An Oasis Of Bird Diversity In Arid Northern Mexico, John Mccormack, Gabriela Castañeda, Greg Levandoski
John E. McCormack
No abstract provided.
Slate-Throated Redstarts (Myioborus Miniatus) Breeding In Maderas Del Carmen, Coahuila, Mexico, John Mccormack
Slate-Throated Redstarts (Myioborus Miniatus) Breeding In Maderas Del Carmen, Coahuila, Mexico, John Mccormack
John E. McCormack
The breeding range of the slate-throated redstart (Myioborus miniatus) stretches from South America to Mexico, where it extends northward along the Sierra Madre Oriental to southeastern Coahuila and along the Sierra Madre Occidental to southern Chihuahua and Sonora. We report the discovery of slate-throated redstarts breeding in the Maderas del Carmen mountains in Coahuila. This represents a range extension of approximately 400 km and is, to our knowledge, the northernmost breeding record for this species.
Precise, Highly Female-Biased Sex Ratios In A Social Spider, Leticia Avilés, John Mccormack, Asher Cutter, Todd Bukowski
Precise, Highly Female-Biased Sex Ratios In A Social Spider, Leticia Avilés, John Mccormack, Asher Cutter, Todd Bukowski
John E. McCormack
It has been recognized for some time that the risk of producing maleless clutches should select for a lower than binomial variance in the sex ratio of organisms with female–biased sex ratios, small clutches and breeding groups containing the clutch of a single female. However, to date, precise sex ratios have only been reported for organisms with haplodiploid sex determination, a system which allows direct control of the sex of individual offspring. In contrast, under heterogametic sex determination chance is expected to play a crucial role in determining the sex composition of any one family, in particular when males are …