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MEPS
Marine Ecology Progress Series

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MEPS 482:279-298 (2013)  -  DOI: https://doi.org/10.3354/meps10265

REVIEW
No evidence of predation causing female-biased sex ratios in marine pelagic copepods

Luiz Felipe Mendes Gusmão1,2,3,*, A. David McKinnon4, Anthony J. Richardson1,2

1Centre for Applications in Natural Resource Mathematics, School of Mathematics and Physics, The University of Queensland, St Lucia, Queensland 4067, Australia
2Climate Adaptation Flagship, CSIRO Marine and Atmospheric Research, Ecosciences Precinct, Dutton Park, Queensland 4102, Australia
3Centro de Biologia Marinha (CEBIMar) and Laboratory of Plankton Systems, Universidade de São Paulo, São Sebastião, SP,
11600-000, Brazil
4Australian Institute of Marine Science, PMB No 3, Townsville MC, Queensland 4810, Australia

ABSTRACT: Although sex ratios close to unity are expected in dioecious species, biased sex ratios are common in nature. It is essential to understand causes of skewed sex ratios in situ, as they can lead to mate limitation and have implications for the success of natural populations. Female-skewed sex ratios are commonly observed in copepods in situ. Here we discuss the challenges of copepod sex ratio research and provide a critical review of factors determining copepod sex ratios, focusing on 2 main objectives. The first is a critique of the male predation theory, which is currently the main process thought to be responsible for female-skewed sex ratios. It assumes that males have higher mortality because of increased vulnerability to predation during their search for mates. We show that there is little support for the male predation theory, that sex ratios skewed toward females occur in the absence of predation, that sex ratios are not related to predation pressure, and that where sex-skewed predation does occur, it is biased toward females. Our second objective is to suggest alternative hypotheses regarding the determination of sex ratios. We demonstrate that environmental factors, environmental sex determination and sex change have strong effects on copepod sex ratios, and suggest that differential physiological longevity of males and females may be more important in determining sex ratios than previously thought. We suggest that copepod sex ratios are the result of a mixture of factors.


KEY WORDS: Sex-specific predation · Sex change · Environmental sex determination · Intersexuality · Longevity · Prey size· Seasonality · Sex ratio · Zooplankton


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Cite this article as: Gusmão LFM, McKinnon AD, Richardson AJ (2013) No evidence of predation causing female-biased sex ratios in marine pelagic copepods. Mar Ecol Prog Ser 482:279-298. https://doi.org/10.3354/meps10265

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