Showing 5451 - 5460 of 5831 Items
Sensory-based niche partitioning in a multiple predator-multiple prey community
Date: 2015-05-20
Creator: Jay J. Falk, Hannah M. Ter Hofstede, Patricia L. Jones, Marjorie M. Dixon, Paul A., Faure, Elisabeth K.V. Kalko, Rachel A. Page
Access: Open access
- Many predators and parasites eavesdrop on the communication signals of their prey. Eavesdropping is typically studied as dyadic predator-prey species interactions; yet in nature, most predators target multiple prey species and most prey must evade multiple predator species. The impact of predator communities on prey signal evolution is not well understood. Predators could converge in their preferences for conspicuous signal properties, generating competition among predators and natural selection on particular prey signal features. Alternatively, predator species could vary in their preferences for prey signal properties, resulting in sensory-based niche partitioning of prey resources. In the Neotropics, many substrate-gleaning bats use the mate-attraction songs of male katydids to locate them as prey. We studied mechanisms of niche partitioning in four substrate- gleaning bat species and found they are similar in morphology, echolocation signal design and prey-handling ability, but each species preferred different acoustic features of male song in 12 sympatric katydid species. This divergence in predator preference probably contributes to the coexistence of many substrate-gleaning bat species in the Neotropics, and the substantial diversity in the mate-attraction signals of katydids. Our results provide insight into how multiple eavesdropping predator species might influence prey signal evolution through sensory-based niche partitioning.
Mémoire et souvenir dans l'imaginaire antillais - Maryse Condé et Fabienne Kanor: Identité et existence noire aux Antilles et en France
Date: 2020-01-01
Creator: Elijah B Koblan-Huberson
Access: Open access
- L’histoire d’un peuple est en grande partie liée à sa mémoire, aux souvenirs et commémorations des évènements passés et des ancêtres.En raison de la colonisation et ses conséquences, les habitants des îles de la Guadeloupe et de la Martinique vivent un malaise vis-à-vis de la mémoire en tant que peuple antillais.Par conséquent, il est important de se demander comment, après la déshumanisation effectuée par l’extermination des premiers habitants, les Caraïbes et les Arawaks, l’esclavagisation des Africains, et la colonisation des territoires antillais, une nouvelle conceptualisation de la mémoire peut mener à une nouvelle conceptualisation de l’existence et de l’identité pour l’être humain antillais qui provient de ceux qui ont été esclavagisés. Pour répondre à la question nous examinerons les romans de Maryse Condé et de Fabienne Kanor.
TAKs, thylakoid membrane protein kinases associated with energy transduction
Date: 1999-04-02
Creator: Shaun Snyders, Bruce D. Kohorn
Access: Open access
- The phosphorylation of proteins within the eukaryotic photosynthetic membrane is thought to regulate a number of photosynthetic processes in land plants and algae. Both light quality and intensity influence protein kinase activity via the levels of reductants produced by the thylakoid electron transport chain. We have isolated a family of proteins called TAKs, Arabidopsis thylakoid membrane threonine kinases that phosphorylate the light harvesting complex proteins. TAK activity is enhanced by reductant and is associated with the photosynthetic reaction center II and the cytochrome b6f complex. TAKs are encoded by a gene family that has striking similarity to transforming growth factor β receptors of metazoans. Thus thylakoid protein phosphorylation may be regulated by a cascade of reductant-controlled membrane-bound protein kinases.
Bowdoin College - Medical School of Maine Catalogue (1905-1906)
Date: 1906-01-01
Access: Open access
- Bowdoin College Bulletin no. 4
Enemy Combatants and Unitary Executives: Presidential Power in Theory and Practice During the War on Terror
Date: 2020-01-01
Creator: Rohini Kurup
Access: Open access
- In the wake of the September 11 attacks, the Bush administration decided that suspected terrorists and those determined to have aided terrorists would be detained and classified as “enemy combatants.” This was a largely new category of prisoners who were neither prisoners of war protected under international law nor civilians. They included noncitizens and citizens—those captured on foreign battlefields and on American soil. They would be detained by the United States, held indefinitely without charge or access to a lawyer, and subject to trial by military commission. The administration’s enemy combatant policies were based on a theory of inherent executive power—that the Constitution gave the president vast and exclusive powers, which allowed him to act unilaterally without Congressional interference or judicial review. This thesis charts the development of and challenges to the enemy combatant policies to understand how they were conceived and what their implications are to the American political system. I argue that by appealing to a theory of inherent executive power to create the policies, the administration subverted traditional checks on presidential power and undermined the rule of law. Ultimately, the dismantling of some of the enemy combatant policies, largely a result of court rulings that challenged the administration’s premise of power, signified a reining in of executive authority. Yet, many aspects of the administration’s counterterrorism apparatus remained past Bush’s years in the White House, leaving a legacy of expanded presidential power for future presidents.
Isolation of Cell Adhesion Mutations in Arabidopsis thaliana Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2020-01-01
Creator: Frances DeCamp Hobart Zorensky
Access: Access restricted to the Bowdoin Community
The role of behavioral diversity in determining the extent to which central pattern generators are modulated
Date: 2020-01-01
Creator: Jacob Salman Kazmi
Access: Open access
- Neuromodulation may be a substrate for the evolution of behavioral diversity. The extent to which a central pattern generator is modulated could serve as a mechanism that enables variability in motor output dependent on an organism’s need for behavioral flexibility. The pyloric circuit, a central pattern generator in the crustacean stomatogastric nervous system (STNS), stimulates contractions of foregut muscles in digestion. Since neuromodulation enables variation in the movements of pyloric muscles, more diverse feeding patterns should be correlated with a higher degree of STNS neuromodulation. Previous data have shown that Cancer borealis, an opportunistic feeder, is sensitive to a wider array of neuromodulators than Pugettia producta, a specialist feeder. The observed difference in modulatory capacity may be coincidental since these species are separated by phylogeny. We predict that the difference in modulatory capacity is a product of a differential need for variety in foregut muscle movements. This study examined two members of the same superfamily as P. producta, the opportunistically feeding snow crab (Chionoecetes opilio) and portly spider crab (Libinia emarginata). Using extracellular recording methods, the responses of isolated STNS preparations to various neuromodulators were measured. Initial qualitative results indicate that the STNS of C. opilio is sensitive to all of these neuromodulators. Additionally, previous data on the neuromodulatory capacity of L. emarginata was supported through similar electrophysiological analysis of the isolated STNS. As a first step in determining the mechanism of differential sensitivity between species, tissue-specific transcriptomes were generated and mined for neuromodulators.