... The five chapters of Part III aim to link evolutionary changes in neural circuits to the evolution of behavior. In Chapter 9, James Newcomb and colleagues describe the neural circuits underlying swimming behavior in various Nudipleura (sea slugs). As it turns out, some nudipleuran species ... et al. report that nonhomologous swimming behaviors can be mediated by neural circuits that include homologous (as well as nonhomologous) neurons and that clearly homologous swimming in closely related species may involve nonhomologous neurons. These findings show that, even for homologous ...

... In Chapter 10, Andrew Bass and Boris Chagnaud review the literature showing that the premotor neurons controlling sound production tend to be derived from caudal rhombomere 8 in ... hindbrain of many different vertebrates, including fishes and amphibians. Something about these neurons makes them especially well suited for complex, often rhythmic, pattern generation and for the coordination ...

... the muscles related to breathing. Bass and Chagnaud further point out that in toadfishes the hindbrain vocal motor neurons lie adjacent to motor neurons innervating the pectoral fins. This ... suggests that the neural circuitry for sound production shares a long evolutionary (and developmental) history with the circuits controlling the pectoral fins and, in tetrapods, the forelimbs. This hypothesis may seem far-fetched at ... ; however, pectoral fins are used for sound production in a number of fishes, and forelimbs are clearly used for gestural communication in humans. If correct, the hypothesis implies a deep homology between behaviors that seem quite ... but involve homologous neural circuits and, presumably, homologous developmental genes....

... James Goodson and colleagues in Chapter 11 examine variation in neuropeptide expression across multiple brain regions involved in avian social behavior. More ... on differences in peptide expression among four emberizid songbird species, examining their correlation with seasonal changes in territoriality and/or flocking behavior. The analysis gets complicated, because variation in the degree of territoriality may be caused by reduced aggression or ... selection allows the authors to identify one set of differences in neuropeptide expression that is most likely linked to differences in aggression and another set that correlates with differences in flocking behavior. As the authors admit, the conclusions are based on just a few species and, ... , tentative. However, the study undeniably reveals an unexpectedly large degree of variation in peptide levels both across species and within species (i.e., seasonal variation). This variation is probably a driving force behind the variation in behavior, although it may also be a ...

... gradients (in odor plumes) as well as local cue constellations (locale-specific odorant mixtures). The hippocampus became specialized to process and integrate these two kinds of information. Subsequently, these functions were extended to other sensory modalities. An interesting corollary of this ...

... predict when and where their food will be available than in species that feed opportunistically....

.... Their star-shaped “nose” evolved to help them in this task, as did a series of related specializations in the brain, including an expanded somatosensory cortex. Catania then turns to an aquatic snake that has evolved a fascinating trick for catching fish. It uses a tiny muscular ...