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Sonia Kleindorfer - One of the best experts on this subject based on the ideXlab platform.
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adaptive divergence in darwin s small ground finch geospiza fuliginosa divergent selection along a cline
Biological Journal of The Linnean Society, 2013Co-Authors: Frank J. Sulloway, Sonia KleindorferAbstract:We examine here, in a single year (2005), phenotypic divergence along a 560-m elevation gradient in Darwin’s small ground finch (Geospiza fuliginosa) in the Galapagos Islands. In this sample, four composite measures of phenotypic traits showed significant differences along the 18-km geographical cline extending from lowlands to Highlands. Compared with lowland birds, highland birds had larger and more pointed beaks, and thicker tarsi, but smaller feet and claws. Finches in an intervening agricultural zone had predominantly intermediate trait values. In a second, mark–recapture study we analyse selection on morphological traits among birds recaptured across years (2000–2005) in lowland and highland habitats. Birds were more likely to survive in the Highlands and during the wet season, as well as if they had large beaks and bodies. In addition, highland birds exhibited higher survival rates if they had small feet and pointed beaks – attributes common to highland birds as a whole. Lowland birds were more likely to survive if they possessed the opposite traits. Selection therefore reinforced existing morphological divergence, which appears to reflect local adaptation to differing resources during the predominantly drought-ridden conditions that characterized the 5-year study. Alternative explanations – including genetic drift, matching habitat choice, deformation by parasites, and the effects of wear – received little or no support. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110, 45–59.
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the ecology of clutch size variation in darwin s small ground finch geospiza fuliginosa comparison between lowland and highland habitats
Ibis, 2007Co-Authors: Sonia KleindorferAbstract:This study examines the ecology of clutch size variation between two contiguous populations of Small Ground Finch Geospiza fuliginosa that breed in geographically distinct habitats (lowlands, Highlands) on Santa Cruz Island of the Galapagos Archipelago. Small clutch size is considered an adaptive response to high predation risk (to reduce behavioural conspicuousness at the nest and lower the energetic costs of re-nesting), whereas high food abundance is predicted to favour large clutch size. This study has two main objectives: (1) to present descriptive data on clutch size variation in G. fuliginosa between habitats, and (2) to test life-history predictions for clutch size variation based on food abundance and nest predation hypotheses. The Highlands on Santa Cruz Island were characterized by high nest predation (52%), high annual rainfall and high insect abundance across the year, whereas the lowlands were characterized by low nest predation (5%), seasonal rainfall and high insect abundance during the breeding season. The highland birds had smaller clutch size and a shorter re-nesting interval. Patterns of nest attendance differed significantly between habitats. The percentage of time incubating per hour was comparable between habitats, but the mean duration per incubation event was longer in the Highlands (with fewer events per hour), which is consistent with the prediction of reduced behavioural conspicuousness at nests under conditions of high predation risk. There were no significant differences in nestling feeding levels between habitats, probably because G. fuliginosa is a multiple prey loader.
Robert M Timm - One of the best experts on this subject based on the ideXlab platform.
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A new species of small-eared shrew in the Cryptotis thomasi species group from Costa Rica (Mammalia: Eulipotyphla: Soricidae)
Mammal Research, 2017Co-Authors: Neal Woodman, Robert M TimmAbstract:We describe a new species of small-eared shrew, genus Cryptotis Pomel, 1848 (Eulipotyphla: Soricidae), from near the community of Monteverde in the Tilarán Highlands of northwestern Costa Rica. The new species is immediately distinguished from all other Costa Rican shrews its large size and long tail. Morphologically, it belongs to the Cryptotis thomasi group of small-eared shrews, a clade that is more typically distributed in the Andes Cordillera and other highland regions of northern South America. The new Costa Rican species and the Panamanian endemic Cryptotis endersi Setzer, 1950 are the only two members of this species group known to occur in Central America. Like most other members of the C. thomasi group for which the postcranial skeleton has been studied, the new species tends be more ambulatory (rather than semi-fossorial) when compared with other members of the genus. Our survey efforts over several decades failed to locate a population of the new species, and we discuss its conservation status in light of its limited potential distribution in the Tilarán Highlands and the significant climatic change that has been documented in the Monteverde region during the past four decades.
Hermann Behling - One of the best experts on this subject based on the ideXlab platform.
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late quaternary vegetation climate and fire history of the araucaria forest and campos region from serra campos gerais paranastate south brazil
Review of Palaeobotany and Palynology, 1997Co-Authors: Hermann BehlingAbstract:New palynological and charcoal data from a bog (24°40′S, 50°13′W, 1200 m asl) of Serra Campos Gerais, northeastern ParanaState, allow a complete and detailed reconstruction of the late Quaternary vegetation and climate history of the South Brazilian Highlands. The late-glacial period, which starts at 12,50014C yr BP, indicates the predominance of a diverse grassland vegetation (campos) with scattered stands of Araucaria forest and Atlantic rain forest, probably growing in valley bottoms. This suggests 3 to 5°C colder and drier climates than at present. Judging from the absence of charcoal, fires must here been rare during late-glacial times. The early and mid-Holocene (until 285014C yr BP) is marked by a predominance of campos vegetation on the Highlands and expansion of tropical rain forest trees in the valleys, indicating warm climates and perhaps an increase in annual precipitation compared to the late-glacial. A migration of Araucaria forest from the valleys onto the Highlands did probably not occur. Seasonal drought is probably the major factor explaining the absence of an expansion of Araucaria forests on the southern Brazilian Highlands in the early and mid-Holocene. Palaeofires were more frequent at the beginning of the Holocene, probably ignited by Amerindians at that time. First expansion in the valleys or an initial migration of Araucaria angustifolia from valleys into the Serra Campos Gerais highland occurred during the late Holocene (2850-153014C yr BP), indicating a wetter climate with a shorter dry season. Fires during this period had the highest frequency and may have influenced the migration of Araucaria into the campos areas. A marked expansion of Araucaria forest, forming a mosaic of grassland and Araucaria forest patches on the Highlands, took place only in the last 1500 years. This suggests onset of a high precipitation climate without a strong annual dry season. Fires were also less frequent. Logging of Araucaria forests occurred during the last centuries.
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late quaternary vegetation climate and fire history from the tropical mountain region of morro de itapeva se brazil
Palaeogeography Palaeoclimatology Palaeoecology, 1997Co-Authors: Hermann BehlingAbstract:Late Quaternary paleoenvironments have been interpreted from a 35,000 yr B.P. pollen and charcoal record from Morro de Itapeva (22°47′S, 45°32′W, 1850 m a.s.l.) in the SE Brazilian Highlands. Changes in taxa composition and elevational shifts in high elevation grassland (campos de altitude), Araucaria forest, cloud forest and Atlantic rain forest, all of which can be found in the study area today, indicate climatic changes in the past. Expanded high elevation grasslands, absence of Araucaria forest, cloud forest and Atlantic rain forest during the recorded last glacial period (ca. 35,000–17,000 yr B.P.) suggest a climate markedly cooler and drier than today. Development of a Sphagnum peat bog, rare presence of Araucaria forest taxa and existence of a narrow cloud forest and rain forest belt at lower elevations during the late glacial period (17,000-ca. 10,000 yr B.P.) indicate a change to a cool and somewhat moister climates. During the early Holocene cloud forest developed close to the study site, reflecting a warm and moist climate on the east facing slopes, but a drier climate on the highland plateau, evidenced by the rare presence of Araucaria and Podocarpus. Only during the late Holocene moisture increases in the Highlands, suggested by the higher frequency of Araucaria and Podocarpus. Fires were more frequent during the last glacial than during the Holocene.
Neal Woodman - One of the best experts on this subject based on the ideXlab platform.
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A new species of small-eared shrew in the Cryptotis thomasi species group from Costa Rica (Mammalia: Eulipotyphla: Soricidae)
Mammal Research, 2017Co-Authors: Neal Woodman, Robert M TimmAbstract:We describe a new species of small-eared shrew, genus Cryptotis Pomel, 1848 (Eulipotyphla: Soricidae), from near the community of Monteverde in the Tilarán Highlands of northwestern Costa Rica. The new species is immediately distinguished from all other Costa Rican shrews its large size and long tail. Morphologically, it belongs to the Cryptotis thomasi group of small-eared shrews, a clade that is more typically distributed in the Andes Cordillera and other highland regions of northern South America. The new Costa Rican species and the Panamanian endemic Cryptotis endersi Setzer, 1950 are the only two members of this species group known to occur in Central America. Like most other members of the C. thomasi group for which the postcranial skeleton has been studied, the new species tends be more ambulatory (rather than semi-fossorial) when compared with other members of the genus. Our survey efforts over several decades failed to locate a population of the new species, and we discuss its conservation status in light of its limited potential distribution in the Tilarán Highlands and the significant climatic change that has been documented in the Monteverde region during the past four decades.
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two new species of shrews soricidae from the western Highlands of guatemala
Journal of Mammalogy, 2010Co-Authors: Neal WoodmanAbstract:The broad-clawed shrews (Soricomorpha: Soricidae: Cryptotis) encompass a clade of 5 species—Cryptotis alticolus (Merriam), C. goldmani (Merriam), C. goodwini Jackson, C. griseoventris Jackson, and C. peregrinus (Merriam)—that is known collectively as the Cryptotis goldmani group and is characterized by broadened forefeet, elongated and broadened fore claws, and broadened humeri. These shrews are distributed in highland regions from central Mexico to Honduras. Two broad-clawed shrews, C. goodwini and C. griseoventris, occur in southern Mexico and Guatemala and are presumed sister species whose primary distinguishing feature is the larger size of C. goodwini. In an investigation of variation within and between these 2 species, I studied characteristics of the postcranial skeleton. Statistical analyses of a variety of character suites indicate that the forelimb morphology in this group exhibits less intraspecific variation and greater interspecific variation than cranio-mandibular morphology, although most skull characters support groupings based on forelimb characters. Together, these characters define 4 distinct groups among the specimens examined. C. griseoventris is restricted to the northern Highlands of Chiapas, Mexico, and C. goodwini occurs in the southern Highlands of Chiapas and Guatemala. Herein, I describe 2 new species of broad-clawed shrews from the Sierra de los Cuchumatanes, Guatemala.
Jeffrey Rossibarra - One of the best experts on this subject based on the ideXlab platform.
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characterization of introgression from the teosinte zea mays ssp mexicana to mexican highland maize
PeerJ, 2019Co-Authors: Eric Gonzalezsegovia, Jeffrey Rossibarra, Garrett M Janzen, Sergio Perezlimon, Carolina G Cintoramartinez, Alejandro Guerrerozavala, Matthew B Hufford, Ruairidh J H SawersAbstract:Background The spread of maize cultivation to the Highlands of central Mexico was accompanied by substantial introgression from the endemic wild teosinte Zea mays ssp. mexicana, prompting the hypothesis that the transfer of beneficial variation facilitated local adaptation. Methods We used whole-genome sequence data to map regions of Zea mays ssp. mexicana introgression in three Mexican highland maize individuals. We generated a genetic linkage map and performed Quantitative Trait Locus mapping in an F2 population derived from a cross between lowland and highland maize individuals. Results Introgression regions ranged in size from several hundred base pairs to Megabase-scale events. Gene density within introgression regions was comparable to the genome as a whole, and over 1,000 annotated genes were located within introgression events. Quantitative Trait Locus mapping identified a small number of loci linked to traits characteristic of Mexican highland maize. Discussion Although there was no strong evidence to associate quantitative trait loci with regions of introgression, we nonetheless identified many Mexican highland alleles of introgressed origin that carry potentially functional sequence variants. The impact of introgression on stress tolerance and yield in the highland environment remains to be fully characterized.
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allele specific expression analysis identifies regulatory variation associated with stress related genes in the mexican highland maize landrace palomero toluqueno
bioRxiv, 2017Co-Authors: Rocio M Aguilarrangel, Jeffrey Rossibarra, Eric Gonzalezsegovia, Ricardo Chavez A Montes, June Simpson, Ruairidh J H SawersAbstract:Background. Gene regulatory variation has been proposed to play an important role in the adaptation of plants to environmental stress. In the central Highlands of Mexico, farmer selection has generated a unique group of maize landraces adapted the challenges of the highland niche. In this study, gene expression in Mexican highland maize and a reference maize breeding line were compared to identify evidence of regulatory variation in stress-related genes. It was hypothesised that local adaptation in Mexican highland maize would be associated with a transcriptional signature observable even under benign conditions. Methods. Allele specific expression analysis was performed using the seedling-leaf transcriptome of an F1 individual generated from the cross between the highland adapted Mexican landrace Palomero Toluqueno and the reference line B73, grown under benign conditions. Results were compared with a published dataset describing the transcriptional response of B73 seedlings to cold, heat, salt and UV treatments. Results. A total of 2386 genes were identified to show allele specific expression. Of these, 277 showed an expression difference between Palomero Toluqueno and B73 alleles that mirrored the response of B73 cold, heat, salt and/or UV treatments, and, as such, were considered to display a constitutive stress response. Constitutive stress response candidates included genes associated with plant hormone signaling and a number of transcription factors. Construction of a gene co-expression network revealed further signaling and stress-related genes to be among the potential targets of the transcription factors candidates. Discussion. Constitutive activation of responses may represent the best strategy when stresses are severe but predictable. Expression differences observed here between Palomero Toluqueno and B73 alleles indicate the presence of cis-acting regulatory variation linked to stress-related genes in Palomero Toluqueno. Considered alongside gene annotation and population data, allele specific expression analysis of plants grown under benign conditions provides an attractive strategy to identify functional variation potentially linked to local adaptation.
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genetic signals of origin spread and introgression in a large sample of maize landraces
Proceedings of the National Academy of Sciences of the United States of America, 2011Co-Authors: Joost Van Heerwaarden, José De Jesús Sánchez González, John Doebley, M M Goodman, William H Briggs, Jeffrey C Glaubitz, Jeffrey RossibarraAbstract:The last two decades have seen important advances in our knowledge of maize domestication, thanks in part to the contributions of genetic data. Genetic studies have provided firm evidence that maize was domesticated from Balsas teosinte (Zea mays subspecies parviglumis), a wild relative that is endemic to the mid- to lowland regions of southwestern Mexico. An interesting paradox remains, however: Maize cultivars that are most closely related to Balsas teosinte are found mainly in the Mexican Highlands where subspecies parviglumis does not grow. Genetic data thus point to primary diffusion of domesticated maize from the Highlands rather than from the region of initial domestication. Recent archeological evidence for early lowland cultivation has been consistent with the genetics of domestication, leaving the issue of the ancestral position of highland maize unresolved. We used a new SNP dataset scored in a large number of accessions of both teosinte and maize to take a second look at the geography of the earliest cultivated maize. We found that gene flow between maize and its wild relatives meaningfully impacts our inference of geographic origins. By analyzing differentiation from inferred ancestral gene frequencies, we obtained results that are fully consistent with current ecological, archeological, and genetic data concerning the geography of early maize cultivation.
