Showing 81 - 90 of 5709 Items
A Men’s College with Women: Masculinity, Sexist Laughter, and Stories of Solidarity during Bowdoin College’s Transition to Coeducation, 1969-1975 Access to this record is restricted to members of the Bowdoin community. Log in here to view.
- Restriction End Date: 2025-06-01
Date: 2020-01-01
Creator: Emma D. Kellogg
Access: Access restricted to the Bowdoin Community
Bowdoin College Catalogue (1951-1952)
Date: 1952-01-01
Access: Open access
- Bowdoin College Bulletin no. 303
Bowdoin College Catalogue (1932-1933)
Date: 1933-01-01
Access: Open access
- Bowdoin College Bulletin no. 207
Incidence, size and spatial structure of clones in second-growth stands of coast redwood, Sequoia sempervirens (Cupressaceae)
Date: 2004-07-01
Creator: Vladimir Douhovnikoff, Adelaide M. Cheng, Richard S. Dodd
Access: Open access
- The ecology and evolutionary potential of coast redwood (Sequoia sempervirens) is significantly influenced by the important role clonal spread plays in its reproduction and site persistence. In nine second-growth stands, amplified fragment length polymorphisms (AFLPs) were used to identify redwood clonal architecture. Clones (multistem genets) dominated sites by representing an average of 70% of stems measured, ranging in size from two to 20 stems. As a result, a relatively small number of genets can monopolize a disproportionate amount of site resources, are more likely to persist over time, and have greater on-site genetic representation. Clones were not limited to fairy-ring structures, but consisted of a wide range of shapes including concentric rings, ring chains, disjunct, and linear structures. Between-ramet distances of up to 40 m were measured, indicating that clonal reproduction is not limited to basal stump resprouting. Clonal structure in second-growth stands was similar to earlier reports from old growth, emphasizing the importance of site persistence and long-term, gradual site development. Smaller ramet numbers per genet in old growth is probably due to local within-genet self thinning. Management and conservation of redwoods will benefit from a better understanding of the dynamics and structure of clonal spread in these forests.
Intron Size Correlates Positively with Recombination Rate in Caenorhabditis elegans
Date: 2004-03-01
Creator: Anuphap Prachumwat, Laura DeVincentis, Michael F. Palopoli
Access: Open access
- A negative correlation between intron size and recombination rate has been reported for the Drosophila melanogaster and human genomes. Population-genetic models suggest that this pattern could be caused by an interaction between recombination rate and the efficacy of natural selection. To test this idea, we examined variation in intron size and recombination rate across the genome of the nematode Caenorhabditis elegans. Interestingly, we found that intron size correlated positively with recombination rate in this species.
Rapid mechanisms for generating genome diversity: Whole ploidy shifts, aneuploidy, and loss of heterozygosity
Date: 2014-01-01
Creator: Richard J. Bennett, Anja Forche, Judith Berman
Access: Open access
- Human fungal pathogens can exist in a variety of ploidy states, including euploid and aneuploid forms. Ploidy change has a major impact on phenotypic properties, including the regulation of interactions with the human host. In addition, the rapid emergence of drug-resistant isolates is often associated with the formation of specific supernumerary chromosomes. Pathogens such as Candida albicans and Cryptococcus neoformans appear particularly well adapted for propagation in multiple ploidy states with novel pathways driving ploidy variation. In both species, heterozygous cells also readily undergo loss of heterozygosity (LOH), leading to additional phenotypic changes such as altered drug resistance. Here, we examine the sexual and parasexual cycles that drive ploidy variation in human fungal pathogens and discuss ploidy and LOH events with respect to their far-reaching roles in fungal adaptation and pathogenesis.
Global divergence of the human follicle mite Demodex folliculorum: Persistent associations between host ancestry and mite lineages
Date: 2015-12-29
Creator: Michael F. Palopoli, Daniel J. Fergus, Samuel Minot, Dorothy T. Pei, W. Brian, Simison, Iria Fernandez-Silva, Megan S. Thoemmes, Robert R. Dunn, Michelle Trautwein
Access: Open access
- Microscopic mites of the genus Demodex live within the hair follicles of mammals and are ubiquitous symbionts of humans, but little molecular work has been done to understand their genetic diversity or transmission. Here we sampled mite DNA from 70 human hosts of diverse geographic ancestries and analyzed 241 sequences from the mitochondrial genome of the species Demodex folliculorum. Phylogenetic analyses recovered multiple deep lineages including a globally distributed lineage common among hosts of European ancestry and three lineages that primarily include hosts of Asian, African, and Latin American ancestry. To a great extent, the ancestral geography of hosts predicted the lineages of mites found on them; 27% of the total molecular variance segregated according to the regional ancestries of hosts. We found that D. folliculorum populations are stable on an individual over the course of years and that some Asian and African American hosts maintain specific mite lineages over the course of years or generations outside their geographic region of birth or ancestry. D. folliculorum haplotypes were much more likely to be shared within families and between spouses than between unrelated individuals, indicating that transmission requires close contact. Dating analyses indicated that D. folliculorum origins may predate modern humans. Overall, D. folliculorum evolution reflects ancient human population divergences, is consistent with an out-of-Africa dispersal hypothesis, and presents an excellent model system for further understanding the history of human movement.
The initiation and development of small peat-forming ecosystems adjacent to lakes in the north central Canadian low arctic during the Holocene
Date: 2017-07-01
Creator: Philip Camill, Charles E. Umbanhowar, Christoph Geiss, Mark B. Edlund, Will O., Hobbs, Allison Dupont, Catherine Doyle-Capitman, Matthew Ramos
Access: Open access
- Small peat-forming ecosystems in arctic landscapes may play a significant role in the regional biogeochemistry of high-latitude systems, yet they are understudied compared to arctic uplands and other major peat-forming regions of the North. We present a new data set of 25 radiocarbon-dated permafrost peat cores sampled around eight low arctic lake sites in northern Manitoba (Canada) to examine the timing of peat initiation and controls on peat accumulation throughout the Holocene. We used macrofossils and charcoal to characterize changes in the plant community and fire, and we explored potential impacts of these local factors, as well as regional climatic change, on rates of C accumulation and C stocks. Peat initiation was variable across and within sites, suggesting the influence of local topography, but 56% of the cores initiated after 3000 B.P. Most cores initiated and remained as drier bog hummock communities, with few vegetation transitions in this landscape. C accumulation was relatively slow and did not appear to be correlated with Holocene-scale climatic variability, but C stocks in this landscape were substantial (mean = 45.4 kg C m ), potentially accounting for 13.2 Pg C in the Taiga Shield ecozone. To the extent that small peat-forming systems are underrepresented in peatland mapping, soil organic carbon (SOC) stocks may be underestimated in arctic regions. Mean fire severity appeared to be negatively correlated with C accumulation rates. Initiation and accumulation of soil C may respond to both regional and local factors, and substantial lowland soil C stocks have the potential for biogeochemical impacts on adjacent aquatic ecosystems. −2
Molecular basis of the copulatory plug polymorphism in Caenorhabditis elegans
Date: 2008-08-21
Creator: Michael F. Palopoli, Matthew V. Rockman, Aye TinMaung, Camden Ramsay, Stephen, Curwen, Andrea Aduna, Jason Laurita, Leonid Kruglyak
Access: Open access
- Heritable variation is the raw material for evolutionary change, and understanding its genetic basis is one of the central problems in modern biology. We investigated the genetic basis of a classic phenotypic dimorphism in the nematode Caenorhabditis elegans. Males from many natural isolates deposit a copulatory plug after mating, whereas males from other natural isolates-including the standard wild-type strain (N2 Bristol) that is used in most research laboratories-do not deposit plugs. The copulatory plug is a gelatinous mass that covers the hermaphrodite vulva, and its deposition decreases the mating success of subsequent males. We show that the plugging polymorphism results from the insertion of a retrotransposon into an exon of a novel mucin-like gene, plg-1, whose product is a major structural component of the copulatory plug. The gene is expressed in a subset of secretory cells of the male somatic gonad, and its loss has no evident effects beyond the loss of male mate-guarding. Although C. elegans descends from an obligate-outcrossing, male?female ancestor, it occurs primarily as self-fertilizing hermaphrodites. The reduced selection on male-male competition associated with the origin of hermaphroditism may have permitted the global spread of a loss-of-function mutation with restricted pleiotropy. ©2008 Macmillan Publishers Limited. All rights reserved.
Bowdoin College Catalogue (1971-1972)
Date: 1972-01-01
Access: Open access
- Bowdoin College Bulletin no. 382