The Experts below are selected from a list of 186 Experts worldwide ranked by ideXlab platform
Craig Moritz - One of the best experts on this subject based on the ideXlab platform.
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range instability leads to cytonuclear discordance in a morphologically cryptic ground squirrel species complex
Molecular Ecology, 2017Co-Authors: Mark A Phuong, Craig MoritzAbstract:The processes responsible for cytonuclear discordance frequently remain unclear. Here, we employed an exon capture data set and demographic methods to test hypotheses generated by species distribution models to examine how contrasting histories of range stability vs. fluctuation have caused cytonuclear concordance and discordance in ground squirrel lineages from the Otospermophilus beecheyi species complex. Previous studies in O. beecheyi revealed three morphologically cryptic and highly divergent mitochondrial DNA lineages (named the Northern, Central and Southern lineages based on geography) with only the Northern lineage exhibiting concordant divergence for nuclear genes. Here, we showed that these mtDNA lineages likely formed in allopatry during the Pleistocene, but responded differentially to climatic changes that occurred since the last interglacial (~120,000 years ago). We find that the Northern lineage maintained a stable range throughout this period, correlating with genetic distinctiveness among all genetic markers and low migration rates with the other lineages. In contrast, our results suggested that the Southern lineage expanded from Baja California Sur during the Late Pleistocene to overlap and potentially swamp a contracting Central lineage. High rates of intraspecific gene flow between Southern lineage individuals among expansion origin and expansion edge populations largely eroded Central ancestry from autosomal markers. However, male-biased dispersal in this system preserved signals of this past hybridization and introgression event in matrilineal-biased X-chromosome and mtDNA markers. Our results highlight the importance of range stability in maintaining the persistence of phylogeographic lineages, whereas unstable range dynamics can increase the tendency for lineages to merge upon secondary contact.
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range stability predicts lineage persistence in a morphologically cryptic ground squirrel species complex
bioRxiv, 2016Co-Authors: Mark A Phuong, Craig MoritzAbstract:The processes responsible for patterns of cytonuclear discordance remain unclear. Here, we employ an exon capture dataset, demographic methods, and species distribution modeling to elucidate the impact of historical demography on patterns of genealogical concordance and discordance in ground squirrel lineages from the Otospermophilus beecheyi species complex. Previous studies in O. beecheyi revealed three morphologically cryptic and highly divergent mitochondrial DNA (mtDNA) lineages (named the Northern, Central, and Southern lineages based on geography) with only the Northern lineage exhibiting concordant divergence in nuclear markers. We show that these mtDNA lineages likely formed in allopatry during the Pleistocene, but responded differentially to climatic changes that occurred since the last interglacial (~120,000 years ago). We find that the Northern lineage maintained a stable range throughout this period, correlating with genetic distinctiveness among all genetic markers and low migration rates between the other lineages. In contrast, our results support a scenario where the Southern lineage expanded from Baja California Sur during the Late Pleistocene and hybridized with the Central lineage, eventually driving the Central lineage to extinction. While high intraspecific gene flow among newly colonized populations eroded significant signals of Central ancestry from autosomal markers, male sex-biased dispersal in this system preserved signals of this past hybridization and introgression event in matrilineal-biased X-chromosome and mtDNA markers. Our results highlight the importance of range stability in maintaining the persistence of phylogeographic lineages, whereas unstable range dynamics can increase the tendency for lineages to interact and collapse upon secondary contact.
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delimiting species in the genus Otospermophilus rodentia sciuridae using genetics ecology and morphology
Biological Journal of The Linnean Society, 2014Co-Authors: Mark A Phuong, Kevin C Rowe, Craig Moritz, Daniel R WaitAbstract:This workwas supported by UC Berkeley Summer Undergradu-ate Research Fellowships to MAP and ML, UC Berke-ley Biology Fellows Program Awards to DRW and MAP,the Museum of Vertebrate Zoology UndergraduateBiodiversity Award, and the NSF DEB 0640859 to CM.
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size increase in high elevation ground squirrels over the last century
Global Change Biology, 2012Co-Authors: Lindsey M Eastman, Toni Lyn Morelli, Kevin C Rowe, Chris J Conroy, Craig MoritzAbstract:There is increasing evidence for morphological change in response to recent environmental change, but how this relates to fluctuations in geographic range remains unclear. We measured museum specimens from two time periods (1902‐1950 and 2000‐2008) that vary significantly in climate to assess if and how two high elevation contracting species of ground squirrels in the Sierra Nevada of California, Belding’s ground squirrel (Urocitellus beldingi) and the golden-mantled ground squirrel (Callospermophilus lateralis), and one lower elevation, stable species, the California ground squirrel (Otospermophilus beecheyi), have responded morphologically to changes over the last century. We measured skull length (condylobasal length), an ontogenetically more labile trait highly correlated with body size, and maxillary toothrow length, a more developmentally constrained trait predictive of skull shape. C. lateralis and U. beldingi, both obligate hibernators, have increased in body size, but have not changed in shape. In contrast, O. beecheyi, which only hibernates in parts of its range, has shown no significant change in either morphometric trait. The increase in body size in the higher elevation species, hypothesized to be a plastic effect due to a longer growing season and thus prolonged food availability, opposes the expected direction of selection for decreased body size under chronic warming. Our study supports that population contraction is related to physiological rather than nutritional constraints.
Breanna J. Putman - One of the best experts on this subject based on the ideXlab platform.
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recent encounters with rattlesnakes enhance ground squirrel responsiveness to predator cues
Behavioral Ecology and Sociobiology, 2017Co-Authors: Rey E Ayon, Breanna J. Putman, Rulon W. ClarkAbstract:A diverse range of prey taxa exhibit stereotyped antipredator behaviors when confronting live predators. Predator cues also elicit antipredator responses, and previous research indicates that prey possess mechanisms to discriminate between the relative risk posed by particular predator cues, which mediates their investment in antipredator behaviors (i.e., “threat-sensitive” behavior). However, the salience of such predator cues may change according to perceived predation risk, which can vary temporally or spatially. We hypothesized that prey modify responses to predatory cues according to their recent experience with predators, which would prime prey to attend to predator-related cues. In the present study, we found that recent encounters with live tethered rattlesnakes increased perceived predation risk in free-ranging California ground squirrels (Otospermophilus beecheyi), leading to concomitant increases in the intensity of antipredator behaviors displayed toward a predator model. The increase in antipredator behavior following snake encounters was higher toward the predator model than a novel object, suggesting that squirrels exhibit threat-sensitive responses toward objects resembling predators. However, squirrels did not treat either of these objects with caution, nor did they differ in antipredator behavior, when presented with the model or novel object when no live snake was encountered. This suggests that increased vigilance following predator encounters modulates responses to predator cues. Such increases in antipredator behavior could assist in detecting nearby predators quickly but could also have indirect effects on prey. Underresponding to predators could lead to death, while overresponding could reduce time spent on other fitness-related activities. Prey balance these costs by using environmental cues to modify antipredator responses. Detecting a live predator in the environment could indicate that the chance of predation is high, which may enhance preys’ antipredator responses. We show that ground squirrels significantly enhance antipredator behaviors toward snake models and novel objects after encountering a live tethered rattlesnake predator. However, the predator model elicited greater antipredator behavior than the novel object following snake encounters, suggesting that squirrels are primed to attend to predator-related cues in this context. Both objects were treated similarly, and with less caution, when no snake was detected. Vigilance following predator interactions therefore mediates threat-sensitive responses to subsequent predator cues.
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ORIGINAL PAPER The
2016Co-Authors: Breanna J. Putman, Richard G. Coss, Rulon W. ClarkAbstract:ontogeny of antipredator behavior: age differences in California ground squirrels (Otospermophilus beecheyi) at multiple stages of rattlesnake encounter
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The Foraging Behavior of Free-ranging Rattlesnakes (Crotalus oreganus) in California Ground Squirrel (Otospermophilus beecheyi) Colonies
Herpetologica, 2016Co-Authors: Breanna J. Putman, Matthew A. Barbour, Rulon W. ClarkAbstract:Abstract Foraging is a key aspect of a species’ ecology and decisions made while foraging affect fitness in many ways. Although much research has focused on snake foraging, only a handful of detailed studies have been conducted on free-ranging individuals, all on Crotalus horridus. We used fixed videography to collect data on free-ranging Northern Pacific Rattlesnake (Crotalus oreganus) behavior to qualitatively test predictions regarding interspecific differences in rattlesnake foraging behavior. We analyzed foraging behaviors based on encounter rates with prey and strike rates on prey, distances moved between consecutive ambush sites, residency time at each site, and poststrike behaviors. Snakes encountered approximately 4 prey/d, with California Ground Squirrels (Otospermophilus beecheyi) being encountered at much higher rates than other prey types. Crotalus oreganus typically did not remain at hunting sites for long durations compared with other species, and generally exhibited short distance movement...
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The ontogeny of antipredator behavior: age differences in California ground squirrels (Otospermophilus beecheyi) at multiple stages of rattlesnake encounters
Behavioral Ecology and Sociobiology, 2015Co-Authors: Breanna J. Putman, Richard G. Coss, Rulon W. ClarkAbstract:Newborn offspring of animals often exhibit fully functional innate antipredator behaviors, but they may also require learning or further development to acquire appropriate responses. Experience allows offspring to modify responses to specific threats and also leaves them vulnerable during the learning period. However, antipredator behaviors used at one stage of a predator encounter may compensate for deficiencies at another stage, a phenomenon that may reduce the overall risk of young that are vulnerable at one or more stages. Few studies have examined age differences in the effectiveness of antipredator behaviors across multiple stages of a predator encounter. In this study, we examined age differences in the antipredator behaviors of California ground squirrels ( Otospermophilus beecheyi ) during the detection, interaction, and attack stages of Pacific rattlesnake ( Crotalus oreganus ) encounters. Using free-ranging squirrels, we examined the ability to detect free-ranging rattlesnakes, snake-directed behaviors after discovery of a snake, and responses to simulated rattlesnake strikes. We found that age was the most important factor in snake detection, with adults being more likely to detect snakes than pups. We also found that adults performed more tail flagging (a predator-deterrent signal) toward snakes and were more likely to investigate a snake’s refuge when interacting with a hidden snake. In field experiments simulating snake strikes, adults exhibited faster reaction times than pups. Our results show that snake detection improves with age and that pups probably avoid rattlesnakes and minimize time spent in close proximity to them to compensate for their reduced reaction times to strikes.
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the fear of unseen predators ground squirrel tail flagging in the absence of snakes signals vigilance
Behavioral Ecology, 2015Co-Authors: Breanna J. Putman, Rulon W. ClarkAbstract:Rather than fleeing from predators, many animals exhibit conspicuous displays that are thought to deter attacks by advertising quality (physical capabilities), or awareness of the predator. However, prey commonly exhibit the same antipredator display when predators are absent. Signaling in this context could either dishonestly indicate predator detection, or honestly indicate vigilance, but no study has tested these hypotheses experimentally. We tested the vigilance advertisement function of tail flagging, a signal given by California ground squirrels (Otospermophilus beecheyi) to rattlesnakes (Crotalus oreganus), by simulating snake strikes and quantifying strike avoidance behaviors in signaling and non-signaling squirrels. We removed the effect of snake presence on signaling by simulating strikes 1) in the presence of a rattlesnake, 2) with no snake present, or 3) in an area where squirrels had recently encountered a snake that was no longer present. Squirrels tail flagged most when interacting with a snake. Squirrels also signaled in areas of recent snake encounters, and in this context, they responded faster to simulated strikes and were more likely to leap vertically or horizontally away from the attack. Tail flagging rate was also related to squirrels’ body displacement time and flee modality. Squirrels rarely signaled or exhibited evasive leaping with no snake present. These results indicate that displays in the absence of predators can honestly signal vigilance, or the readiness to avoid an attack, even if predators are undetected. Such antipredator displays may be widespread as many species could benefit from advertising alertness when uncertain of the location of predators.
Rulon W. Clark - One of the best experts on this subject based on the ideXlab platform.
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recent encounters with rattlesnakes enhance ground squirrel responsiveness to predator cues
Behavioral Ecology and Sociobiology, 2017Co-Authors: Rey E Ayon, Breanna J. Putman, Rulon W. ClarkAbstract:A diverse range of prey taxa exhibit stereotyped antipredator behaviors when confronting live predators. Predator cues also elicit antipredator responses, and previous research indicates that prey possess mechanisms to discriminate between the relative risk posed by particular predator cues, which mediates their investment in antipredator behaviors (i.e., “threat-sensitive” behavior). However, the salience of such predator cues may change according to perceived predation risk, which can vary temporally or spatially. We hypothesized that prey modify responses to predatory cues according to their recent experience with predators, which would prime prey to attend to predator-related cues. In the present study, we found that recent encounters with live tethered rattlesnakes increased perceived predation risk in free-ranging California ground squirrels (Otospermophilus beecheyi), leading to concomitant increases in the intensity of antipredator behaviors displayed toward a predator model. The increase in antipredator behavior following snake encounters was higher toward the predator model than a novel object, suggesting that squirrels exhibit threat-sensitive responses toward objects resembling predators. However, squirrels did not treat either of these objects with caution, nor did they differ in antipredator behavior, when presented with the model or novel object when no live snake was encountered. This suggests that increased vigilance following predator encounters modulates responses to predator cues. Such increases in antipredator behavior could assist in detecting nearby predators quickly but could also have indirect effects on prey. Underresponding to predators could lead to death, while overresponding could reduce time spent on other fitness-related activities. Prey balance these costs by using environmental cues to modify antipredator responses. Detecting a live predator in the environment could indicate that the chance of predation is high, which may enhance preys’ antipredator responses. We show that ground squirrels significantly enhance antipredator behaviors toward snake models and novel objects after encountering a live tethered rattlesnake predator. However, the predator model elicited greater antipredator behavior than the novel object following snake encounters, suggesting that squirrels are primed to attend to predator-related cues in this context. Both objects were treated similarly, and with less caution, when no snake was detected. Vigilance following predator interactions therefore mediates threat-sensitive responses to subsequent predator cues.
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ORIGINAL PAPER The
2016Co-Authors: Breanna J. Putman, Richard G. Coss, Rulon W. ClarkAbstract:ontogeny of antipredator behavior: age differences in California ground squirrels (Otospermophilus beecheyi) at multiple stages of rattlesnake encounter
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The Foraging Behavior of Free-ranging Rattlesnakes (Crotalus oreganus) in California Ground Squirrel (Otospermophilus beecheyi) Colonies
Herpetologica, 2016Co-Authors: Breanna J. Putman, Matthew A. Barbour, Rulon W. ClarkAbstract:Abstract Foraging is a key aspect of a species’ ecology and decisions made while foraging affect fitness in many ways. Although much research has focused on snake foraging, only a handful of detailed studies have been conducted on free-ranging individuals, all on Crotalus horridus. We used fixed videography to collect data on free-ranging Northern Pacific Rattlesnake (Crotalus oreganus) behavior to qualitatively test predictions regarding interspecific differences in rattlesnake foraging behavior. We analyzed foraging behaviors based on encounter rates with prey and strike rates on prey, distances moved between consecutive ambush sites, residency time at each site, and poststrike behaviors. Snakes encountered approximately 4 prey/d, with California Ground Squirrels (Otospermophilus beecheyi) being encountered at much higher rates than other prey types. Crotalus oreganus typically did not remain at hunting sites for long durations compared with other species, and generally exhibited short distance movement...
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The ontogeny of antipredator behavior: age differences in California ground squirrels (Otospermophilus beecheyi) at multiple stages of rattlesnake encounters
Behavioral Ecology and Sociobiology, 2015Co-Authors: Breanna J. Putman, Richard G. Coss, Rulon W. ClarkAbstract:Newborn offspring of animals often exhibit fully functional innate antipredator behaviors, but they may also require learning or further development to acquire appropriate responses. Experience allows offspring to modify responses to specific threats and also leaves them vulnerable during the learning period. However, antipredator behaviors used at one stage of a predator encounter may compensate for deficiencies at another stage, a phenomenon that may reduce the overall risk of young that are vulnerable at one or more stages. Few studies have examined age differences in the effectiveness of antipredator behaviors across multiple stages of a predator encounter. In this study, we examined age differences in the antipredator behaviors of California ground squirrels ( Otospermophilus beecheyi ) during the detection, interaction, and attack stages of Pacific rattlesnake ( Crotalus oreganus ) encounters. Using free-ranging squirrels, we examined the ability to detect free-ranging rattlesnakes, snake-directed behaviors after discovery of a snake, and responses to simulated rattlesnake strikes. We found that age was the most important factor in snake detection, with adults being more likely to detect snakes than pups. We also found that adults performed more tail flagging (a predator-deterrent signal) toward snakes and were more likely to investigate a snake’s refuge when interacting with a hidden snake. In field experiments simulating snake strikes, adults exhibited faster reaction times than pups. Our results show that snake detection improves with age and that pups probably avoid rattlesnakes and minimize time spent in close proximity to them to compensate for their reduced reaction times to strikes.
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the fear of unseen predators ground squirrel tail flagging in the absence of snakes signals vigilance
Behavioral Ecology, 2015Co-Authors: Breanna J. Putman, Rulon W. ClarkAbstract:Rather than fleeing from predators, many animals exhibit conspicuous displays that are thought to deter attacks by advertising quality (physical capabilities), or awareness of the predator. However, prey commonly exhibit the same antipredator display when predators are absent. Signaling in this context could either dishonestly indicate predator detection, or honestly indicate vigilance, but no study has tested these hypotheses experimentally. We tested the vigilance advertisement function of tail flagging, a signal given by California ground squirrels (Otospermophilus beecheyi) to rattlesnakes (Crotalus oreganus), by simulating snake strikes and quantifying strike avoidance behaviors in signaling and non-signaling squirrels. We removed the effect of snake presence on signaling by simulating strikes 1) in the presence of a rattlesnake, 2) with no snake present, or 3) in an area where squirrels had recently encountered a snake that was no longer present. Squirrels tail flagged most when interacting with a snake. Squirrels also signaled in areas of recent snake encounters, and in this context, they responded faster to simulated strikes and were more likely to leap vertically or horizontally away from the attack. Tail flagging rate was also related to squirrels’ body displacement time and flee modality. Squirrels rarely signaled or exhibited evasive leaping with no snake present. These results indicate that displays in the absence of predators can honestly signal vigilance, or the readiness to avoid an attack, even if predators are undetected. Such antipredator displays may be widespread as many species could benefit from advertising alertness when uncertain of the location of predators.
Santos-moreno Antonio - One of the best experts on this subject based on the ideXlab platform.
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Registros notables de tres especies de mamíferos del estado de Oaxaca, México
Universidad Nacional Autónoma de México., 2014Co-Authors: Ruiz-velásquez Elder, Andrés-reyes, Julia Venus, Santos-moreno AntonioAbstract:ResumenEn este estudio se documenta el primer caso de depredación de un vertebrado por el murciélago Artibeus jamaicensis, el registro de la nutria neotropical de río Lontra longicaudis más distal de su distribución en la vertiente del golfo de México, en Oaxaca y el registro con mayor elevación para México; finalmente, la segunda y tercera localidades para el estado y el límite más sureño de la distribución de la ardilla terrestre Otospermophilus variegatus.AbstractThis study documents the following: the first case of vertebrate predation by the fruit-eating bat Artibeus jamaicensis, the most distal point of distribution on the slope of the Gulf of Mexico in Oaxaca and highest altitude recorded in Mexico for the neotropical river otter Lontra longicaudis; the second and third localities for the state and the southernmost limit of distribution for the ground squirrel Otospermophilus variegatus
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Registros notables de tres especies de mamíferos del estado de Oaxaca, México
'Revista Mexicana de Biodiversidad', 2014Co-Authors: Andrés-reyes, Julia Venus, Santos-moreno AntonioAbstract:En este estudio se documenta el primer caso de depredación de un vertebrado por el murciélago Artibeus jamaicensis, el registro de la nutria neotropical de río Lontra longicaudis más distal de su distribución en la vertiente del golfo de México, en Oaxaca y el registro con mayor elevación para México; finalmente, la segunda y tercera localidades para el estado y el límite más sureño de la distribución de la ardilla terrestre Otospermophilus variegatu
Michael J Yabsley - One of the best experts on this subject based on the ideXlab platform.
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southern plains woodrats neotoma micropus from southern texas are important reservoirs of two genotypes of trypanosoma cruzi and host of a putative novel trypanosoma species
Vector-borne and Zoonotic Diseases, 2013Co-Authors: Roxanne A Charles, Sonia A Kjos, Angela E Ellis, John C Barnes, Michael J YabsleyAbstract:Trypanosoma cruzi, the causative agent of Chagas' disease, is an important public health and veterinary pathogen. Although human cases are rare in the United States, infections in wildlife, and in some areas domestic dogs, are common. In 2008 and 2010, we investigated T. cruzi prevalence in possible vertebrate reservoirs in southern Texas, with an emphasis on southern plains woodrats (Neotoma micropus). Infection status was determined using a combination of culture isolation, polymerase chain reaction (PCR), and serologic testing. Based on PCR and/or culture, T. cruzi was detected in 35 of 104 (34%) woodrats, 3 of 4 (75%) striped skunks (Mephitis mephitis), 12 of 20 (60%) raccoons (Procyon lotor), and 5 of 28 (18%) other rodents including a hispid cotton rat (Sigmodon hispidus), rock squirrel (Otospermophilus variegatus), black rat (Rattus rattus), and two house mice (Mus musculus). Additionally, another Trypanosoma species was detected in 41 woodrats, of which 27 were co-infected with T. cruzi. Genetic characterization of T. cruzi revealed that raccoon, rock squirrel, and cotton rat isolates were genotype TcIV, while woodrats and skunks were infected with TcI and TcIV. Based on the Chagas Stat-Pak assay, antibodies were detected in 27 woodrats (26%), 13 raccoons (65%), 4 skunks (100%), and 5 other rodents (18%) (two white-ankled mice [Peromyscus pectoralis laceianus], two house mice, and a rock squirrel). Seroprevalence based on indirect immunofluorescence antibody testing was higher for both woodrats (37%) and raccoons (90%), compared with the Chagas Stat-Pak. This is the first report of T. cruzi in a hispid cotton rat, black rat, rock squirrel, and white-ankled mouse. These data indicate that based on culture and PCR testing, the prevalence of T. cruzi in woodrats is comparable with other common reservoirs (i.e., raccoons and opossums) in the United States. However, unlike raccoons and opossums, which tend to be infected with a particular genotype, southern plains woodrats were infected with TcI and TcIV at near equal frequencies.
