Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/06/26 13:25:44」(JST)

wiki en

Look up semelparous in Wiktionary, the free dictionary.

Look up iteroparous in Wiktionary, the free dictionary.

Semelparity and iteroparity refer to the reproductive strategy of an organism. A species is considered semelparous if it is characterized by a single reproductive episode before death, and iteroparous if it is characterized by multiple reproductive cycles over the course of its lifetime. Some plant scientists use the parallel terms monocarpy and polycarpy. (See also plietesials.)

In truly semelparous species, death after reproduction is part of an overall strategy that includes putting all available resources into maximizing reproduction, at the expense of future life (see "Trade-offs", below). In any iteroparous population there will be some individuals who die between their first and second reproductive episodes, but unless this is part of a syndrome of programmed death after reproduction, this would not be called semelparity.

This distinction is also related to the difference between annual and perennial plants. An annual is a plant that completes its life cycle in a single season, and is usually semelparous. Perennials live for more than one season and are usually (but not always) iteroparous.^[1]

Overview[edit]

Semelparity[edit]

The Pacific salmon is an example of a semelparous organism

The word semelparity was coined by evolutionary biologist Lamont Cole^[2], and comes from the name of the Greek heroine "Semele", who, according to legend, simultaneously gave birth to the infant Dionysus and died. Semelparity is also known as "big bang" reproduction, since the single reproductive event of semelparous organisms is usually large, as well as fatal.^[3] A classic example of a semelparous organism is Pacific salmon (Oncorhynchus spp.), which lives for many years in the ocean before swimming to the freshwater stream of its birth, laying eggs, and dying. Other semelparous animals include many insects, including some species of butterflies, cicadas, and mayflies, many arachnids, and some molluscs such as squid and octopus.

Semelparity also occurs in smelt and capelin, but is very rare in vertebrates other than bony fish. In amphibians, it is known only among some Hyla frogs including the gladiator frog;^[4] in reptiles only a few lizards such as Labord's chameleon of southwestern Madagascar^[5] and Sceloporus bicanthalis of the high mountains of Mexico;^[6] and among mammals only in a few didelphid and dasyurid marsupials.^[7] Annual plants, including all grain crops and most domestic vegetables, are semelparous. Long-lived semelparous plants include century plant (agave), Lobelia telekii, and some species of bamboo.^[8]

Iteroparity[edit]

An iteroparous organism is one that can undergo many reproductive events throughout its lifetime. The pig is an example of an iteroparous organism

The term iteroparity comes from the Latin itero, to repeat, and pario, to beget. An example of an iteroparous organism is a human—though many people may choose only to have one child, humans are biologically capable of having offspring many times over the course of their lives. Iteroparous vertebrates include all birds, most reptiles, virtually all mammals, and most fish. Among invertebrates, most mollusca and many insects (for example, mosquitoes and cockroaches) are iteroparous. Most perennial plants are iteroparous.

Semelparity vs. iteroparity[edit]

Trade-offs[edit]

Iteroparous reproductive effort

An organism has a limited amount of energy available, and must partition it among various functions. Of relevance here is the trade-off between fecundity, growth and survivorship in its life history strategy. These trade-offs come into play in the evolution of iteroparity and semelparity. It has been repeatedly demonstrated that semelparous species produce more offspring in their single fatal reproductive episode than do closely related iteroparous species in any one of theirs.

Models based on non-linear trade-offs[edit]

One class of models that tries to explain the differential evolution of semelparity and iteroparity examines the shape of the trade-off between offspring produced and offspring forgone. In economic terms, offspring produced is equivalent to a benefit function, while offspring forgone is comparable to a cost function. The reproductive effort of an organism—the proportion of energy that it puts into reproducing, as opposed to growth or survivorship—occurs at the point where the distance between offspring produced and offspring forgone is the greatest.^[9] The accompanying graph shows the offspring-produced and offspring-forgone curves for an iteroparous organism:

Semelparous reproductive effort

In the first graph, the marginal cost of offspring produced is decreasing (each additional offspring is less "expensive" than the average of all previous offspring) and the marginal cost of offspring forgone is increasing. In this situation, the organism only devotes a portion of its resources to reproduction, and uses the rest of its resources on growth and survivorship so that it can reproduce again in the future.^[10] However, it is also possible (second graph) for the marginal cost of offspring produced to increase, and for the marginal cost of offspring forgone to decrease. When this is the case, it is favorable for the organism to reproduce a single time. The organism devotes all of its resources to that one episode of reproduction, so it then dies. This mathematical/graphical model has found only limited quantitative support from nature.

Bet-hedging models[edit]

A second set of models examines the possibility that iteroparity is a hedge against unpredictable juvenile survivorship (avoiding putting all one's eggs in one basket). Again, mathematical models have not found empirical support from real-world systems. In fact, many semelparous species live in habitats characterized by high (not low) environmental unpredictability, such as deserts and early successional habitats.

Cole's Paradox and demographic models[edit]

The models that have the strongest support from living systems are demographic. In Lamont Cole's classic 1954 paper, he came to an interesting conclusion:

For an annual species, the absolute gain in intrinsic population growth which could be achieved by changing to the perennial reproductive habit would be exactly equivalent to adding one individual to the average litter size.^[11]

For example, imagine two species—an iteroparous species that has annual litters averaging three offspring each, and a semelparous species that has one litter of four, and then dies. These two species have the same rate of population growth, which suggests that even a tiny fecundity advantage of one additional offspring would favor the evolution of semelparity. This is known as Cole's Paradox.

In his analysis, Cole assumed that there was no mortality of individuals of the iteroparous species, even seedlings. Twenty years later, Charnov and Schaffer ^[12] showed that reasonable differences in adult and juvenile mortality yield much more reasonable costs of semelparity, essentially solving Cole's paradox. An even more general demographic model was produced by Young.^[13]

These demographic models have been more successful than the other models when tested with real-world systems. It has been shown that semelparous species have higher expected adult mortality, making it more economical to put all reproductive effort into the first (and therefore final) reproductive episode.^[14]^[15]

r/K selection[edit]

Semelparity can be a characteristic of r strategists, and iteroparity a characteristic of K strategists.^[16]

References[edit]

^ Gotelli, Nicholas J. (2008). A Primer of Ecology. Sunderland, Mass.: Sinauer Associates, Inc. ISBN 978-0-87893-318-1
^ Cole, Lamont C. (June 1954). "The Population Consequences of Life History Phenomena". The Quarterly Review of Biology 29 (2): 103–137. Retrieved June 22 2013.
^ Robert E. Ricklefs and Gary Leon Miller (1999). Ecology. Macmillan ISBN 0-7167-2829-X
^ Andersson, Matle; Sexual Selection; p. 242. ISBN 0691000573
^ "A unique life history among tetrapods: An annual chameleon living mostly as an egg"
^ "Demography of a Semelparous, High-Elevation Population of Sceloporus bicanthalis (Lacertilia: Phrynosomatidae) from the Nevado de Toluca Volcano, Mexico" in The Southwestern Naturalist 56(1):71-77. 2011
^ Leiner, Natalia O.; Setz, Eleonore Z. F.; Silva, Wesley R. (February 2008). "Semelparity and Factors Affecting the Reproductive Activity of the Brazilian Slender Opossum (Marmosps paulensis) in Southeastern Brazil". Journal of Mammalogy (American Society of Mammalogists) 89 (1): 153–158. doi:10.1644/07-MAMM-A-083.1. Retrieved 2010-10-15.
^ Young, Truman P.; Carol K. Augspurger (1991). "Ecology and evolution of long-lived semelparous plants". Trends in Ecology and Evolution 6 (9): 285–289. doi:10.1016/0169-5347(91)90006-J. PMID 21232483.
^ Paul Moorcroft, "Life History Strategies" (lecture, Harvard University, Cambridge, MA 9 February 2009).
^ Roff, Derek A. (1992). The Evolution of Life Histories. Springer ISBN 0-412-02391-1
^ Lamont C. Cole. "The Population Consequences of Life History Phenomena." The Quarterly Review of Biology 29, no. 2 (June 1954): 103-137
^ Charnov, E.L. and W.M. Schaffer. 1973. Life history consequences of natural selection: Cole’s result revisited. American Naturalist 107:791-793
^ Young, T.P. 1981. A general model of comparative fecundity for semelparous and iteroparous life histories. American Naturalist 118:27-36
^ Young, T.P. 1990. The evolution of semelparity in Mount Kenya lobelias. Evolutionary Ecology 4: 157-171
^ Lesica, P. & T.P. Young. 2005. Demographic model explains life history evolution in Arabis fecunda. Functional Ecology 19:471-477
^ Michael Begon, Colin R. Townsend, John L. Harper (2006). Ecology: from individuals to ecosystems. Wiley-Blackwell ISBN 1-4051-1117-8

English Journal

Short- and long-term effects of litter size manipulation in a small wild-derived rodent.

Lehto Hürlimann M1, Stier A, Scholly O, Criscuolo F, Bize P.Author information 1Department of Ecology and Evolution, University of Lausanne, Switzerland.AbstractIteroparous organisms maximize their overall fitness by optimizing their reproductive effort over multiple reproductive events. Hence, changes in reproductive effort are expected to have both short- and long-term consequences on parents and their offspring. In laboratory rodents, manipulation of reproductive efforts during lactation has however revealed few short-term reproductive adjustments, suggesting that female laboratory rodents express maximal rather than optimal levels of reproductive investment as observed in semelparous organisms. Using a litter size manipulation (LSM) experiment in a small wild-derived rodent (the common vole; Microtus arvalis), we show that females altered their reproductive efforts in response to LSM, with females having higher metabolic rates and showing alternative body mass dynamics when rearing an enlarged rather than reduced litter. Those differences in female reproductive effort were nonetheless insufficient to fully match their pups' energy demand, pups being lighter at weaning in enlarged litters. Interestingly, female reproductive effort changes had long-term consequences, with females that had previously reared an enlarged litter being lighter at the birth of their subsequent litter and producing lower quality pups. We discuss the significance of using wild-derived animals in studies of reproductive effort optimization.
Biology letters.Biol Lett.2014 Mar 26;10(3):20131096. doi: 10.1098/rsbl.2013.1096. Print 2014.
Iteroparous organisms maximize their overall fitness by optimizing their reproductive effort over multiple reproductive events. Hence, changes in reproductive effort are expected to have both short- and long-term consequences on parents and their offspring. In laboratory rodents, manipulation of rep
PMID 24671828

COOPERATIVE BREEDING FAVOURS MATERNAL INVESTMENT IN SIZE OVER NUMBER OF EGGS IN SPIDERS.

Grinsted L1, Breuker CJ, Bilde T.Author information 1Department of Bioscience, Aarhus University, Ny Munkegade 116, 8000, Aarhus C, Denmark. l.grinsted@sussex.ac.uk.AbstractThe transition to cooperative breeding may alter maternal investment strategies depending on density of breeders, extent of reproductive skew and allo-maternal care. Change in optimal investment from solitary to cooperative breeding can be investigated by comparing social species with non-social congeners. We tested two hypotheses in a mainly semelparous system: that social, cooperative breeders, compared to subsocial, solitarily breeding congeners, 1) lay fewer and larger eggs because larger offspring compete better for limited resources and become reproducers; 2) induce egg size variation within clutches as a bet-hedging strategy to ensure that some offspring become reproducers. Within two spider genera, Anelosimus and Stegodyphus, we compared species from similar habitats and augmented the results with a mini-meta-analysis of egg numbers depicted in phylogenies. We found that social species indeed laid fewer, larger eggs than subsocials, while egg size variation was low overall, giving no support for bet-hedging. We propose that the transition to cooperative breeding selects for producing few, large offspring because reproductive skew and high density of breeders and young create competition for resources and reproduction. Convergent evolution has shaped maternal strategies similarly in phylogenetically distant species and directed cooperatively breeding spiders to invest in quality rather than quantity of offspring. This article is protected by copyright. All rights reserved.
Evolution; international journal of organic evolution.Evolution.2014 Mar 21. doi: 10.1111/evo.12411. [Epub ahead of print]
The transition to cooperative breeding may alter maternal investment strategies depending on density of breeders, extent of reproductive skew and allo-maternal care. Change in optimal investment from solitary to cooperative breeding can be investigated by comparing social species with non-social con
PMID 24654980

Mother knows best, even when stressed? Effects of maternal exposure to a stressor on offspring performance at different life stages in a wild semelparous fish.

Sopinka NM1, Hinch SG, Middleton CT, Hills JA, Patterson DA.Author information 1Pacific Salmon Ecology and Conservation Laboratory, Department of Forest and Conservation Sciences, University of British Columbia, 2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada, natsopinka@gmail.com.AbstractThe environment mothers are exposed to has resonating effects on offspring performance. In iteroparous species, maternal exposure to stressors generally results in offspring ill-equipped for survival. Still, opportunities for future fecundity can offset low quality offspring. Little is known, however, as to how intergenerational effects of stress manifest in semelparous species with only a single breeding episode. Such mothers would suffer a total loss of fitness if offspring cannot survive past multiple life stages. We evaluated whether chronic exposure of female sockeye salmon (Oncorhynchus nerka) to a chase stressor impaired offspring performance traits. Egg size and early offspring survival were not influenced by maternal exposure to the repeated acute stressor. Later in development, fry reared from stressed mothers swam for shorter periods of time but possessed a superior capacity to re-initiate bouts of burst swimming. In contrast to iteroparous species, the mechanisms driving the observed effects do not appear to be related to cortisol, as egg hormone concentrations did not vary between stressed and undisturbed mothers. Sockeye salmon appear to possess buffering strategies that protect offspring from deleterious effects of maternal stress that would otherwise compromise progeny during highly vulnerable stages of development. Whether stressed sockeye salmon mothers endow offspring with traits that are matched or mismatched for survival in the unpredictable environment they encountered is discussed. This study highlights the importance of examining intergenerational effects among species-specific reproductive strategies, and across offspring life history to fully determine the scope of impact of maternal stress.
Oecologia.Oecologia.2014 Mar 12. [Epub ahead of print]
The environment mothers are exposed to has resonating effects on offspring performance. In iteroparous species, maternal exposure to stressors generally results in offspring ill-equipped for survival. Still, opportunities for future fecundity can offset low quality offspring. Little is known, howeve
PMID 24619199

Japanese Journal

1回繁殖型非線形Leslie行列モデルの大域漸近安定性 (第10回生物数学の理論とその応用)

今隆助
数理解析研究所講究録 1917, 153-158, 2014-09
NAID 110009846123

Senemorphism: a novel perspective on aging patterns and its implication for diet-related biology

Trindade Lucas Siqueira,Balduino Alex,Aigaki Toshiro,Heddle Jonathan G.
Biogerontology 13(4), 457-466, 2012-08
… Such distinct diet-related senescence is analogous to the divergent aging processes and causes of death observed between castes of social insects, such as queens versus workers ("caste-related-senescence") and also between breeding versus non-breeding semelparous animals ("reproduction-related-senescence"). …
NAID 120005121774

A review of the ecological parameters and implications of subsociality in Parastrachia japonensis (Hemiptera : Cydnidae), a semelparous species that specializes on a poor resource