Competition as a selective mechanism for larger offspring size in guppies
Highly competitive environments are predicted to select for larger offspring. Guppies Poecilia reticulata from low-predation populations have evolved to make fewer, larger offspring than their counterparts from high-predation populations. As predation co-varies with the strength of competition in na...
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Published in | Oikos Vol. 117; no. 1; pp. 104 - 113 |
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Main Author | |
Format | Journal Article |
Language | English |
Published |
Copenhagen
Copenhagen : Blackwell Publishing Ltd
01.01.2008
Blackwell Publishing Ltd Blackwell Publishing Blackwell |
Subjects | |
Online Access | Get full text |
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Summary: | Highly competitive environments are predicted to select for larger offspring. Guppies Poecilia reticulata from low-predation populations have evolved to make fewer, larger offspring than their counterparts from high-predation populations. As predation co-varies with the strength of competition in natural guppy populations, here I present two laboratory experiments that evaluate the role of competition in selecting for larger offspring size. In the first experiment, paired groups of large and small newborns from either a high- or a low-predation population were reared in mesocosms under a high- or a low-competition treatment. While large newborns retained their size advantage over small newborns in both treatments, newborn size increased growth only in the high-competition treatment. Moreover, the increase in growth with size was greater in guppies derived from the low-predation population. In the second experiment, pairs of large and small newborns were reared in a highly competitive environment until reproductive maturity. Small size at birth delayed maturation and the effect of birth size on male age of maturity was greater in the low-predation population. These results support the importance of competition as a selective mechanism in offspring size evolution. |
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Bibliography: | http://dx.doi.org/10.1111/j.2007.0030-1299.16094.x ArticleID:OIK16094 istex:8576DD11575792DC3F8BA60DBFC681395C6F5CBA ark:/67375/WNG-3QSRNZC7-6 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0030-1299 1600-0706 |
DOI: | 10.1111/j.2007.0030-1299.16094.x |