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Contemporary Morphological Evolution In A Lacustrine Population Of Threespine Stickleback, Rose Watts
Contemporary Morphological Evolution In A Lacustrine Population Of Threespine Stickleback, Rose Watts
Biology
In the face of rapidly changing environments, some populations go through contemporary evolution in response to altered selective pressures. In this situation, changes in morphology and behavior can be observed to monitor phenotypic transitions. In adaptive radiations such as the threespine stickleback, Gasterosteus aculeatus, species complex, both re-expression of ancestral phenotypes and the expression of novel phenotypes have been detected. I monitored a population of threespine stickleback in Lynne Lake, Alaska, which is undergoing rapid environmental changes due in part to an increase in primary productivity in the lake. Changes have been documented in the body size and foraging behavior …
Quantification Of Phenotypic Variation In Populations Of Newfoundland Threespine Stickleback (Gasterosteus Aculeatus), Nathan R. Biedak
Quantification Of Phenotypic Variation In Populations Of Newfoundland Threespine Stickleback (Gasterosteus Aculeatus), Nathan R. Biedak
Biology
Phenotypic variation in morphology driven by ecological factors has been well characterized in Alaskan and British Columbian populations of threespine stickleback, with studies demonstrating that the variation is extensive in a wide variety of anti-predator traits and body shape. In contrast, the limited published studies of stickleback in eastern North America suggest that there is relatively little among-population phenotypic variation in anti-predatory armor and body shape. Recent samples obtained from 30 populations of stickleback in Newfoundland, from a wide array of habitats, indicate that the earlier suggestion of relatively limited phenotypic diversity may need to be reevaluated. Using geomorphic morphometrics …
Evolution Of Nervous System Centralization: Role Of Bmp Signaling In Neural Fate And Dorsal-Ventral Axis Specification In Capitella Teleta, Christie Joyce
Evolution Of Nervous System Centralization: Role Of Bmp Signaling In Neural Fate And Dorsal-Ventral Axis Specification In Capitella Teleta, Christie Joyce
Biology
Bone Morphogenetic Protein (BMP) signaling plays an important role in establishing the dorsal-ventral (D-V) axis across Bilateria. BMP signaling has also been implicated in neural fate specification in several bilaterians that possess centralized nervous systems. The classic examples are found in vertebrates and Drosophila melanogaster, where opposing gradients of BMP2/4/Dpp and Chordin/Sog specify the D-V axis and the nervous system arises on the Chordin/Sog side of the early embryo due to the anti-neural role of BMPs. These similarities have been used as support for the hypothesis that the bilaterian ancestor possessed a centralized nervous system and that BMP signaling delimited …