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• 1. [Article] Climate and Ecological Change in Oligo-Miocene Mammals

  xiii, 198 p. : ill. (some col.)

  Citation × Citation Citation Abstract Copy Title: Climate and Ecological Change in Oligo-Miocene Mammals Author: Orcutt, John D. Year: 2012, 2011 xiii, 198 p. : ill. (some col.) Title: Climate and Ecological Change in Oligo-Miocene Mammals Author: Orcutt, John D. Year: 2012, 2011 xiii, 198 p. : ill. (some col.) Close

• 2. [Article] The Effect of Group Size on Individual Roles and the Potential for Cooperation in Group Bubble-net Feeding Humpback Whales (Megaptera novaeangliae)

  Group foraging is observed in many species as a means to increase the ability of members of the group to find and exploit patchy prey. Group foraging can be exhibited in a number of different contexts ...

  Citation × Citation Citation Abstract Copy Title: The Effect of Group Size on Individual Roles and the Potential for Cooperation in Group Bubble-net Feeding Humpback Whales (Megaptera novaeangliae) Author: Mastick, Natalie Group foraging is observed in many species as a means to increase the ability of members of the group to find and exploit patchy prey. Group foraging can be exhibited in a number of different contexts based on the relationships between the participants, including by-product mutualism. One variant of by-product mutualism is cooperation, in which individuals achieve a greater energetic gain by feeding together than they would alone. In cooperation, individuals adopt a role in the group, and in the most complex interactions there may be multiple roles, resulting in a division of labor that occasionally includes role specialization. Humpback whales (Megaptera novaeangliae) are one of the few baleen whale species that have been observed feeding in groups, utilizing behaviors that are hypothesized to be cooperative. One of these behaviors is group bubble-net feeding, which has been observed in the Northeastern Pacific, Northwestern Atlantic, and Southern Oceans. This study utilized multi-sensor archival tag data from 26 humpback whales from the southern Gulf of Maine, 4 from Southeast Alaska, and 1 from the Western Antarctic Peninsula to analyze individual bubble-net feeding behaviors and compare these across populations. Linear mixed effects models were used to determine if dive behaviors varied with group sizes to test the hypothesis that group size influences individual behavior. The results indicate that individuals in the southern Gulf of Maine, for which sufficient data were available, were consistent in their bubble-net feeding behaviors across group sizes, which suggests that individuals utilize set roles in group feeding events. There was evidence for a division of labor and role specialization among whales utilizing certain bubble-net feeding tactics in the southern Gulf of Maine. The three populations performed different variations of bubble-net feeding that are likely based on the speed and schooling patterns of the prey. The results are consistent with the hypothesis that bubble-net feeding is an example of by-product mutualism in these populations, though was not enough data to suggest that group bubble-net feeding in Southeast Alaska was a form of by-product mutualism. The prevalence of herding dives in feeding groups suggest that each individual takes on a role to herd the prey to the surface, and provide evidence against a producer-scrounger relationship in the southern Gulf of Maine, and potentially in the Western Antarctic Peninsula. Title: The Effect of Group Size on Individual Roles and the Potential for Cooperation in Group Bubble-net Feeding Humpback Whales (Megaptera novaeangliae) Author: Mastick, Natalie Group foraging is observed in many species as a means to increase the ability of members of the group to find and exploit patchy prey. Group foraging can be exhibited in a number of different contexts based on the relationships between the participants, including by-product mutualism. One variant of by-product mutualism is cooperation, in which individuals achieve a greater energetic gain by feeding together than they would alone. In cooperation, individuals adopt a role in the group, and in the most complex interactions there may be multiple roles, resulting in a division of labor that occasionally includes role specialization. Humpback whales (Megaptera novaeangliae) are one of the few baleen whale species that have been observed feeding in groups, utilizing behaviors that are hypothesized to be cooperative. One of these behaviors is group bubble-net feeding, which has been observed in the Northeastern Pacific, Northwestern Atlantic, and Southern Oceans. This study utilized multi-sensor archival tag data from 26 humpback whales from the southern Gulf of Maine, 4 from Southeast Alaska, and 1 from the Western Antarctic Peninsula to analyze individual bubble-net feeding behaviors and compare these across populations. Linear mixed effects models were used to determine if dive behaviors varied with group sizes to test the hypothesis that group size influences individual behavior. The results indicate that individuals in the southern Gulf of Maine, for which sufficient data were available, were consistent in their bubble-net feeding behaviors across group sizes, which suggests that individuals utilize set roles in group feeding events. There was evidence for a division of labor and role specialization among whales utilizing certain bubble-net feeding tactics in the southern Gulf of Maine. The three populations performed different variations of bubble-net feeding that are likely based on the speed and schooling patterns of the prey. The results are consistent with the hypothesis that bubble-net feeding is an example of by-product mutualism in these populations, though was not enough data to suggest that group bubble-net feeding in Southeast Alaska was a form of by-product mutualism. The prevalence of herding dives in feeding groups suggest that each individual takes on a role to herd the prey to the surface, and provide evidence against a producer-scrounger relationship in the southern Gulf of Maine, and potentially in the Western Antarctic Peninsula. Close

• 3. [Article] Community gradients of Arctic macrolichens in relation to succession, grazing and the environment

  The purpose of this dissertation was to define macrolichen community gradients in relation to succession, grazing and the environment. First, species scores indicating when macrolichen species appeared ...

  Citation × Citation Citation Abstract Copy Title: Community gradients of Arctic macrolichens in relation to succession, grazing and the environment Author: Holt, Emily A. The purpose of this dissertation was to define macrolichen community gradients in relation to succession, grazing and the environment. First, species scores indicating when macrolichen species appeared following disturbance were derived from the literature. Weighted averaging of these data with a community matrix created a successional score for each sample unit of interest. These scores are surrogates for community age for subsequent analyses. I then described lichen community structure and its relation to the environment in the Bering Land Bridge National Preserve (BELA) in northwestern Alaska. Two primary gradients in lichen community composition were related to habitat rockiness and a substrate-topographic gradient. Next, I sought impacts of grazing by reindeer and caribou on lichen communities. I found lightly grazed areas had taller lichens, greater total lichen cover and minor but significant changes in community structure than heavily grazed sites. Lichen species richness, however, did not differ by grazing status. To create a generalized recovery model, I used plots in burned areas and found total lichen and bryophyte cover varied with time since fire (range 4-49 yrs since fire), while vascular plant cover showed no trend. I then compared these patterns to BELA, an area of unknown disturbance history. Low lichen cover in BELA may not necessarily reflect disturbance but rather site or climatic differences. Lastly, I found that all 17 GIS variables separated lichen communities to some degree. Separation of lichen communities by variable ranged from strong (Alaska Subsections, soil and surficial geology variables) to weak (Watersheds and Reindeer Ownership). The quality of the underlying relationships, how finely the groups are divided and the average patch size of each variable also contribute to differences in how clearly lichen communities were separated. This work will serve as a baseline for future comparisons to understand implications of climate and land use change on lichen communities. My grazing results may inform managers of the implications of heavy grazing and underscore protection and monitoring of prolific and diverse sites. In addition, this work contributes a new method to age tundra communities and a list of GIS variable successful at separating lichen communities. Title: Community gradients of Arctic macrolichens in relation to succession, grazing and the environment Author: Holt, Emily A. The purpose of this dissertation was to define macrolichen community gradients in relation to succession, grazing and the environment. First, species scores indicating when macrolichen species appeared following disturbance were derived from the literature. Weighted averaging of these data with a community matrix created a successional score for each sample unit of interest. These scores are surrogates for community age for subsequent analyses. I then described lichen community structure and its relation to the environment in the Bering Land Bridge National Preserve (BELA) in northwestern Alaska. Two primary gradients in lichen community composition were related to habitat rockiness and a substrate-topographic gradient. Next, I sought impacts of grazing by reindeer and caribou on lichen communities. I found lightly grazed areas had taller lichens, greater total lichen cover and minor but significant changes in community structure than heavily grazed sites. Lichen species richness, however, did not differ by grazing status. To create a generalized recovery model, I used plots in burned areas and found total lichen and bryophyte cover varied with time since fire (range 4-49 yrs since fire), while vascular plant cover showed no trend. I then compared these patterns to BELA, an area of unknown disturbance history. Low lichen cover in BELA may not necessarily reflect disturbance but rather site or climatic differences. Lastly, I found that all 17 GIS variables separated lichen communities to some degree. Separation of lichen communities by variable ranged from strong (Alaska Subsections, soil and surficial geology variables) to weak (Watersheds and Reindeer Ownership). The quality of the underlying relationships, how finely the groups are divided and the average patch size of each variable also contribute to differences in how clearly lichen communities were separated. This work will serve as a baseline for future comparisons to understand implications of climate and land use change on lichen communities. My grazing results may inform managers of the implications of heavy grazing and underscore protection and monitoring of prolific and diverse sites. In addition, this work contributes a new method to age tundra communities and a list of GIS variable successful at separating lichen communities. Close