![]() Type species of these putative piscivore lineages are shown in figure 1 additional species in each of the eight lineages are figured in the supplemental material (see for all online suppl. Based on available dietary data, members of eight subgenera feed primarily on fish. All fish-hunting cone snails can be assigned to the genus Conus, which has been recently subdivided into 57 subgenera primarily based on molecular phylogenetic data (each well-supported lineage has been given subgenus rank). ![]() The cone snails (family Conidae) are venomous, predatory gastropods comprising 750 described species, and of these, probably more than 100 hunt fish. Fish-Hunting Conus: From Behavior to Biochemistry And because cones have radiated so recently and explosively, and their hunting behavior can be observed in the field and even more closely in the laboratory, a sufficiently rich biological context is often available to permit reconstruction of multiple facets of the trajectory of change. Because the peptide venoms of cone snails are encoded directly in their genomes, the histories of these key enabling technologies are relatively more straightforward to trace and define than in other lineages. We review the history and diversity of the fish-hunting lineages and attempt to show how what they learned is connected with how they evolved. The phylogenies also show how prey shifts evolved in concert with behaviors, venom delivery methods, venom pharmacologies and other traits. Increasingly, detailed phylogenetic reconstructions of the Conidae show that some prey specializations found within the family, such as hunting fish and other mollusks, evolved more than once and in some cases through multiple intermediate steps. The ancestors of modern cones hunted worms, as do many extant cone snail species. Here, we argue that fish-hunting cone snails provide some of the best opportunities to elucidate the role of behavior as a catalyst in the evolution of biochemical, developmental, physiological and ecological diversity. But there appear to be few cases where those macroevolutionary consequences can be demonstrated. These ‘Baldwin effect' processes are widely believed to promote evolutionary diversification, and instances of present-day plasticity are frequently used to illustrate how learning or other forms of phenotypic flexibility might lead to speciation and higher-order phenotypic divergence of entire lineages. This idea traces back at least to Baldwin, and by the end of the 20th century, it had given rise to rich literatures on topics such as phenotypic plasticity and genetic assimilation. Many authors have suggested that changes in behavior (or other flexible phenotypes) would be expected to precede changes in physiology and structure, by enabling individuals to exploit a new adaptive opportunity in advance of the genetic changes that would later refine and extend the adaptation. The system presented here may be one of the best examples where diversity in structure, physiology and molecular features were initially driven by particular pathways selected through behavior. Mapping behavior, biochemical components and radular tooth features onto phylogenetic trees shows that fish-hunting behavior emerged at least twice during evolution. Derived fish-hunting behavior clearly also correlates with physical features of the radular tooth, the device that injects these biochemical components. The first two fish-hunting behaviors are clearly associated with distinct groups of venom components, called cabals, which act in concert to modify the behavior of prey in a specific manner. The first sections introduce three different hunting behaviors associated with piscivory: ‘taser-and-tether', ‘net-engulfment' and ‘strike-and-stalk'. ![]() In this article, we attempt to reconstruct events resulting in this shift in food resource by closely examining patterns of behavior, biochemical agents (toxins) that facilitate prey capture and the combinations of toxins present in extant species. The venomous fish-hunting cone snails (Conus) comprise eight distinct lineages evolved from ancestors that preyed on worms.
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