Academic literature on the topic 'Hypermetamorphism'

The inconsistencies discussed in chapter 1 point toward two fundamental problems in need of solution: how to relate the environmental influence inherent in phenotype development to the genetic emphasis of evolutionary theory—Lewontin’s dilemma—and how to view the diverse phenomena of plasticity and development so as to illuminate evolutionary thinking in new ways—Wallace’s challenge. This chapter briefly describes some important, previously recognized connections among phenotypic flexibility, development, and evolution. It then defines key concepts for the chapters that follow. Important contributions toward a synthesis of development and evolution have accumulated over a period of many years. Some insights appear repeatedly in that cycle of inspiration and amnesia that characterizes important discoveries ahead of their times (for a concise review, see Hall, 1992, pp. 171-174). Some of these insights deal with the phenomenology of development and evolution—evidence that certain behavioral and developmental phenomena have influenced evolution in particular groups or in particular ways. These ideas, long familiar to evolutionary biologists, are the starting points for any attempt at a modern synthesis. Each of them will reappear again in later chapters. It does not require great sophistication in biology to realize that juveniles and adults have distinctive, divergent adaptations. Familiar extreme examples are the caterpillar and the butterfly, the tadpole and the frog. In such metamorphosing species, the juvenile has a dramatically different morphology, behavior, and ecology from that of the adult. Some hypermetamorphic insects show a striking series of differently specialized larval stages, and it is probably true of most organisms that juveniles and adults have different, evolved characteristics appropriate to their different niches, if for no other reason than the different requirements for dispersal, respiration, feeding, and defense that confront individuals of differing size (Schmidt-Nielsen, 1984; see also McKinney and McNamara, 1991). As a corrolary of this, different life stages evolve semi-independently. Thus, immature stages may evolve and diversify, undergoing their own adaptive radiations. Many authors have been impressed with the conservatism of certain aspects of early development.