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Evolutionary coherence of the mammalian amygdala.

ABSTRACT: Despite great interest in the role of the amygdala in animal and human behaviour, its very existence as a structurally and functionally unified brain component has been questioned, on the grounds that cell groups within it display divergent pharmacological and connectional characteristics. We argue that the question of whether particular brain nuclei constitute a valid structural and functional unit is inherently an evolutionary question, and we present a method for answering it. The method involves phylogenetic analysis of comparative data to determine whether or not separate regions of the putative brain structure show statistically correlated evolution. We find that, in three separate groups of mammals (primates and two groups of insectivores), evolutionary changes in the volumes of amygdala components are strongly correlated, even after controlling for volumetric change in a wide range of limbic and other brain structures. This allows us to reject the strong claim that the amygdala is neither a structural nor a functional unit, and demonstrates the importance of evolutionary analysis in resolving such issues in systems neuroscience.

SUBMITTER: Barton RA

PROVIDER: S-EPMC1691272 | biostudies-literature | 2003 Mar

REPOSITORIES: biostudies-literature

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Publications

Evolutionary coherence of the mammalian amygdala.

Barton Robert A RA Aggleton John P JP Grenyer Richard R

Proceedings. Biological sciences 20030301 1514

Despite great interest in the role of the amygdala in animal and human behaviour, its very existence as a structurally and functionally unified brain component has been questioned, on the grounds that cell groups within it display divergent pharmacological and connectional characteristics. We argue that the question of whether particular brain nuclei constitute a valid structural and functional unit is inherently an evolutionary question, and we present a method for answering it. The method invo ...[more]

PMID: 12641910

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Project description:BACKGROUND: Sucking lice (Phthiraptera: Anoplura) are obligate, permanent ectoparasites of eutherian mammals, parasitizing members of 12 of the 29 recognized mammalian orders and approximately 20% of all mammalian species. These host specific, blood-sucking insects are morphologically adapted for life on mammals: they are wingless, dorso-ventrally flattened, possess tibio-tarsal claws for clinging to host hair, and have piercing mouthparts for feeding. Although there are more than 540 described species of Anoplura and despite the potential economical and medical implications of sucking louse infestations, this study represents the first attempt to examine higher-level anopluran relationships using molecular data. In this study, we use molecular data to reconstruct the evolutionary history of 65 sucking louse taxa with phylogenetic analyses and compare the results to findings based on morphological data. We also estimate divergence times among anopluran taxa and compare our results to host (mammal) relationships. RESULTS: This study represents the first phylogenetic hypothesis of sucking louse relationships using molecular data and we find significant conflict between phylogenies constructed using molecular and morphological data. We also find that multiple families and genera of sucking lice are not monophyletic and that extensive taxonomic revision will be necessary for this group. Based on our divergence dating analyses, sucking lice diversified in the late Cretaceous, approximately 77 Ma, and soon after the Cretaceous-Paleogene boundary (ca. 65 Ma) these lice proliferated rapidly to parasitize multiple mammalian orders and families. CONCLUSIONS: The diversification time of sucking lice approximately 77 Ma is in agreement with mammalian evolutionary history: all modern mammal orders are hypothesized to have diverged by 75 Ma thus providing suitable habitat for the colonization and radiation of sucking lice. Despite the concordant timing of diversification events early in the association between anoplurans and mammals, there is substantial conflict between the host and parasite phylogenies. This conflict is likely the result of a complex history of host switching and extinction events that occurred throughout the evolutionary association between sucking lice and their mammalian hosts. It is unlikely that there are any ectoparasite groups (including lice) that tracked the early and rapid radiation of eutherian mammals.

Dataset Information

Evolutionary coherence of the mammalian amygdala.

Publications

Evolutionary coherence of the mammalian amygdala.

Similar Datasets

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