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Researchers Test Life History Theory on Island Rule

Dec 10, 2019

Animals on islands often show distinctive differences in life-history traits, such as body size and egg size, when compared with neighboring mainland populations; this is known as the island rule.

Life-history theory predicts that oviparous animals on islands will produce enlarged eggs because of increased maternal investment to improve offspring performance to facilitate intra-specific competition. The life-history theory, developed during the 1950s, provides a possible explanation for the "island rule", but this rule has seldom been tested.

Researchers from the Xinjiang Institute of Ecology and Geography (XIEG) of the Chinese Academy of Sciences evaluated the relationship between egg size and offspring fitness of frogs on 20 islands in the Zhoushan Archipelago and two nearby mainland sites.

To exclude covarying effects, they compared larval performance among different egg sizes in three levels: among siblings within clutches, among clutches within populations, and among different islands.

The researchers found that frogs on most of the islands did produce enlarged eggs and that their larvae had improved larval fitness. Additionally, at all three levels, the offspring that evolved from enlarged eggs had increased offspring fitness.

Their results indicate that, for the first time, the life-history theory predictions concerning egg size and offspring fitness are supported.

The study entitled "Enlarged egg size increases offspring fitness of a frog species on the Zhoushan Archipelago of China" was published in Scientific Reports and supported by China's Biodiversity Observation Network (Sino-BON).

Contact

LIU Jie

Xinjiang Institute of Ecology and Geography

E-mail:

Enlarged Egg Size Increases Offspring Fitness of a Frog Species on the Zhoushan Archipelago of China

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