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Larva

About: Larva is a research topic. Over the lifetime, 2594 publications have been published within this topic receiving 56416 citations. The topic is also known as: larvae & larval.


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Journal ArticleDOI
28 Dec 1973-Science
TL;DR: It is proposed that as development proceeds, variation in exponential growth coefficients causes a trend from a normal distribution to a skewed distribution of body sizes, and the relation between the ecological model and the physiological mechanisms that initiate metamorphosis can only be suggested.
Abstract: A synthetic theory of the ecology of amphibian metamorphosis is founded on the observation that the large variation in length of larval period and body size at metamorphosis typical of a particular species of amphibian cannot be directly explained by differences in dates of hatching or egg sizes. It is proposed that as development proceeds, variation in exponential growth coefficients causes a trend from a normal distribution to a skewed distribution of body sizes. The degree of skewing increases and the median of the distribution decreases with increasing initial densities of populations. The relative advantages of the largest members of a cohort may arise from a variety of mechanisms including the production of growth inhibitors, interference competition, and size-selective feeding behavior. These mechanisms result in a nonnormal distribution of competitive ability, a possible source of the density-dependent competition coefficient found in systems with many species (1). In our model the ranges of body sizes and dates of metamorphosis are determined by a minimum body size that must be obtained and a maximum body size that will not be exceeded at metamorphosis. Between these two size thresholds the endocrinological initiation of metamorphosis is expected to be related to the recent growth history of the individual larva. Species that exploit uncertain environments will have a wide range of possible sizes at metamorphosis. Species exploiting relatively certain environments will have a narrower range. The evolution of neoteny and direct development logically follow from the application of these ideas to the ecological context of the evolution of amphibian life histories. Species that live in constant aquatic habitats surrounded by hostile environments (desert ponds, caves, high-altitude lakes) may evolve permanent larvae genetically incapable of metamorphosis. Other populations may evolve a facultative metamorphosis such that populations are a mixture of neotenes and terrestrial adults. Direct development results from selection to escape the competition, predation, and environmental uncertainty characteristic of some aquatic habitats and is usually accompanied by parental care. The relation between our ecological model and the physiological mechanisms that initiate metamorphosis can only be suggested and it remains an open problem for developmental biologists.

1,243 citations

Journal ArticleDOI
01 Feb 1988-Ecology
TL;DR: Results demonstrate a direct relationship between phenotypic variation generated in the larval stage and adult traits closely associated with an individual's fitness.
Abstract: The relationships among timing of metamorphosis, size at metamorphosis, and traits related to adult fitness were studied for 8 yr in the salamander Ambystoma talpoideum at a temporary pond. Among years, the modal time of metamorphosis and mean body size at metamorphosis were positively correlated with the date the pond dried. In years that the pond dried late, one group of larvae metamorphosed well before the pond dried, whereas the other group metamorphosed just before pond drying. Mean body size of late—metamorphosing individuals was not greater than that of individuals metamorphosing early. Early—metamorphosing males and females were larger at first and second reproduction than were late—metamorphosing individuals. Independent of timing of metamorphosis, larger juveniles at metamorphosis were also larger adults at first reproduction. Age at first reproduction for males was not associated with timing of or size at metamorphosis but large early—metamorphosing females reproduced at a younger age than did small early—metamorphosing females. Neither time of metamorphosis nor size at metamorphosis was associated with survival to first reproduction. These results demonstrate a direct relationship between phenotypic variation generated in the larval stage and adult traits closely associated with an individual's fitness.

871 citations

Journal ArticleDOI
David C. Smith1
01 Apr 1987-Ecology
TL;DR: Unless breeding during the Ist yr led to higher mortality of large individuals, survival rate after meetamorphosis was not related to size or date at metamorphosis.
Abstract: A cohort of tadpoles of the chorus frog, Pseudacris triseriata, on Isle Royale, Michigan, was marked to determine the effect of body size and date at metamorphosis on survivorship to maturity. The cohort was classified at metamorphosis into four categories based on size and date of metamorphosis: large-early, small-early, large-late, and small- late. The number of frogs in each category that returned to breed on the study area was monitored for the following 2 yr. Long larval period and small body size at metamorphosis influenced recruitment to the breeding population by delaying maturity. Frogs that meta- morphosed at large size maintained their size advantage at maturity. Large body size and early date at metamorphosis increased survivorship to maturity by enhancing the chance that reproductive size was attained within 1 yr of metamorphosis. Frogs that were recap- tured in the 2nd yr after metamorphosis, when all frogs had attained mature size, were from all four categories in the same proportions marked at metamorphosis, indicating that unless breeding during the Ist yr led to higher mortality of large individuals, survival rate after metamorphosis was not related to size or date at metamorphosis.

808 citations

Journal ArticleDOI
01 Aug 1990-Ecology
TL;DR: The population appeared to be regulated through density-dependent factors affecting larval survival, larval size, and time of metamorphosis, as well as adult population size, which also affected total clutch volume.
Abstract: During a 7-yr population study on the wood frog, Rana sylvatica, the breed- ing population size fluctuated by a factor of 10 and juvenile production by a factor of 100. Variation in the adult population among years was largely due to variation in juvenile recruitment. Annual net replacement rates (Ro) varied from 0.009 to 7.49. Survivorship curves (calculated using the number of eggs deposited as the initial point) showed that most variation in the proportion of individuals surviving to adulthood was due to variation in larval survival; juvenile and adult survival was relatively constant among years. Male and female survival did not differ. Because females matured a year later than males, on average 2.3 times as many males as females from a given clutch survived to breed. This difference accounted for the observed male-biased sex ratio in breeding choruses. Pre- metamorphic survival and size at metamorphosis were negatively correlated with the number of eggs deposited. Length of larval period was positively correlated with number of eggs deposited. Survival was higher among juveniles that metamorphosed early and were large at metamorphosis. Larger juveniles matured earlier and were also larger as adults. The population appeared to be regulated through density-dependent factors affecting larval survival, larval size, and time of metamorphosis. Adult population size also nega- tively affected total clutch volume. Mean monthly rainfall positively affected adult survival.

789 citations

Journal ArticleDOI
TL;DR: Three environmental cues influence both the entry into and exit from the developmentally arrested dispersal stage called the dauer larva: a dauer-inducing pheromone, food, and temperature.

579 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20231,475
20223,416
202182
202061
201968
201857