The evolutionary process in talitrid amphipods and salamanders in changing environments, with a discussion of "genetic assimilation" and some other evolutionary concepts

Abstract

MATSUDA, R. 1982. The evolutionary process in talitrid amphipods and salamanders in changing environments, with a discussion of "genetic assimilation" and some other evolutionary concepts. Can. J . Zool. 60: 733-749. The evolutionary process of talitrid amphipods and salamanders involving neoteny in changing environments consists of the aspect of environmental induction of structural changes as a result of altered activity of the preexisting endocrine mechanism and the aspect of natural selection which results in canalization of development and genetic assimilation of the modified (neotenous) phenotype. The prevalence of genetic assimilation is discussed, along with the cases where traditional neo-Darwinism applies. By taking the fact of environment-hormonal induction of gene regulation and the aspect of natural selection into account, mechanisms of macroevolution, ,preadaptation, plasticity in morphogenesis, and a mode of speciation are discussed. A historical review is presented concerning the theories (the Baldwin effect and Weismann's theory) related to genetic assimilation and neo-Darwinism.MATSUDA, R. 1982. The evolutionary process in talitrid amphipods and salamanders in changing environments, with a discussion of "genetic assimilation" and some other evolutionary concepts. Can. J. Zool. 60: 733-749. Le processus Cvolutif qui implique la nCotCnie dans des milieux changeants chez les amphipodes talitridCs et chez les salamandres rel&ve d'une part de l'induction Ccologique des changements structuraux qui rksultent de I'activitC modifiCe du mkcanisme endocrinien prkexistant et, d'autre part, de la sClection naturelle qui entraine la canalisation du dCveloppement et l'assimilation gCnCtique du phCnotype modifiC (nCotCnique). La discussion porte sur la prkdominance de l'assimilation gCnCtique ainsi que sur l'application, en certains cas, du nCodarwinisme traditionnel. Sont analysis aussi les mCcanismes de macr&volution, la prkadaptation, la plasticit6 au cours de la morphogen&se et le mode de spkciation, a la lumi&re de l'induction Ccologique et hormonale de la rkgulation gCnCtique et a la lumi&re aussi du phCnom&ne de sClection naturelle. Une revue historique des thCories (effet Baldwin et thCorie de Weismann) relikes a l'assimilation gCnCtique et au nCodarwinisme est prCsentCe Cgalement . [Traduit par le journal]No organism can grow and develop without environmental stimuli. However, integration of this most fundamental biological principle into the study of evolution has been almost a taboo for a long time, and for some historical reasons (p. 746). Nevertheless, I shall attempt below to examine closely, based on the available evidence, the significance of the morphogenetic effect of environmental factors in evolution, while attempting to see how environments have acted also as selective agents during the same evolutionary process.To see the environmental effect clearly, I have chosen talitrid amphipods which have changed their habitat from sea to land during phylogeny, and salamanders which normally change ...

Developmental Plasticity, Genetic Differentiation, and Hypoxia-induced Trade-offs in an African Cichlid Fish

“…As Matsuda [8] and Hall [10] point out, it is very difficult to prove in nature that genetic changes that have taken place were preceded by similar plastic changes. In fact, this scarcity of evidence has led several evolutionary biologists to propose that genetic assimilation is not an important process in evolution [19,[24][25][26].…”

“…For more than a century there has been considerable enthusiasm among evolutionary biologists for the hypothesis that phenotypic plasticity facilitates evolutionary change by allowing the survival of populations in a different environment, followed by a slower evolutionary response as a result of selection for a better adaptedness to the changed environment [e.g., [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Hence, phenotypic plasticity is hypothesized to smooth the fitness landscape facilitating evolutionary transitions among alternative phenotypes [17,18].…”

“…These concepts are very similar (see e.g., [7,8,20,21] for discussions). The term genetic assimilation was meant to be interpreted in the broadest sense by Waddington [7], encompassing the organic selection of Baldwin, Morgan, and Osborn (i.e.…”

Phenotypic Plasticity and the Origins of Diversity

“…However, all socially parasitic species (believed derived from them by phenotype fixation-224) have independently evolved parallel morphological traits associated with aggressive parasitism, namely enlarged mandibles, a thick cuticle, and a recurved sting (224). Matsuda (127) noted that an accumulation of new specialization commonly accompanies phenotype fixation involving neotenous morphs. Although he regarded this as a kind of reaction to neotenous simplification ("material compensation"), the pattern may represent that predicted here as a result of phenotype fixation.…”

Evolutionary role of phenotypic plasticity

“…Возможно, по этой схеме шла эволюция саламандр рода Ambystoma, у которых не выходящие на сушу педоморфные формы и на-земные метаморфы исходно были двумя альтерна-тивными фенотипами, определяемыми средой (раз-мером водоема); в дальнейшем некоторые виды стали облигатными педоморфами, а другие -об-лигатными метаморфами [34].…”