Does predation control adult sex ratios and longevities in marine pelagic copepods?

A.G. Hirst, D. Bonnet, D.V.P. Conway, Thomas Kiørboe

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

We assess the causes of adult sex ratio skew in marine pelagic copepods by examining changes in these ratios between the juveniles and adults, sexual differences in juvenile stage durations, and mortality rates of adults in the field and laboratory (when free from predators). In the field, late copepodite stages (CIV and CV) commonly have sex ratios that are either not significantly different from equity (1 : 1), or slightly male biased. By contrast, in adults, these ratios are commonly significantly biased toward female dominance. Sex ratio skews are therefore primarily attributable to processes in adults. Members of the non-Diaptomoidea have especially skewed adult ratios; in the members Oithonidae and Clausocalanidae this is not generated from differences between male and female adult physiological longevity (i.e., laboratory longevity when free of predators). In the genera Acartia, Oithona, and Pseudocalanus, we estimate that predation mortality contributed $ 69% of the field mortality rate in adult males, whereas in Acartia, Oithona, and Calanus adult females, this is $ 36%.We conclude that (1) adult sex ratio skew in pelagic copepods is primarily due to differential mortality of the sexes in the adult stage and not in juveniles, (2) mortality rates of adult Acartia, Pseudocalanus, and Oithona are dominated by predation mortality rather than physiological longevity (except under extreme food limitation), and (3) in Pseudocalanus and Oithona, elevated mortality rates in adult males to females is predominantly due to higher predation on males. Our work demonstrates that we now need to develop a more comprehensive understanding of the importance of feeding preferences in predators.
Original languageEnglish
JournalLimnology and Oceanography
Volume55
Issue number5
Pages (from-to)2193-2206
ISSN0024-3590
DOIs
Publication statusPublished - 2010

Cite this

Hirst, A.G. ; Bonnet, D. ; Conway, D.V.P. ; Kiørboe, Thomas. / Does predation control adult sex ratios and longevities in marine pelagic copepods?. In: Limnology and Oceanography. 2010 ; Vol. 55, No. 5. pp. 2193-2206.
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title = "Does predation control adult sex ratios and longevities in marine pelagic copepods?",
abstract = "We assess the causes of adult sex ratio skew in marine pelagic copepods by examining changes in these ratios between the juveniles and adults, sexual differences in juvenile stage durations, and mortality rates of adults in the field and laboratory (when free from predators). In the field, late copepodite stages (CIV and CV) commonly have sex ratios that are either not significantly different from equity (1 : 1), or slightly male biased. By contrast, in adults, these ratios are commonly significantly biased toward female dominance. Sex ratio skews are therefore primarily attributable to processes in adults. Members of the non-Diaptomoidea have especially skewed adult ratios; in the members Oithonidae and Clausocalanidae this is not generated from differences between male and female adult physiological longevity (i.e., laboratory longevity when free of predators). In the genera Acartia, Oithona, and Pseudocalanus, we estimate that predation mortality contributed $ 69{\%} of the field mortality rate in adult males, whereas in Acartia, Oithona, and Calanus adult females, this is $ 36{\%}.We conclude that (1) adult sex ratio skew in pelagic copepods is primarily due to differential mortality of the sexes in the adult stage and not in juveniles, (2) mortality rates of adult Acartia, Pseudocalanus, and Oithona are dominated by predation mortality rather than physiological longevity (except under extreme food limitation), and (3) in Pseudocalanus and Oithona, elevated mortality rates in adult males to females is predominantly due to higher predation on males. Our work demonstrates that we now need to develop a more comprehensive understanding of the importance of feeding preferences in predators.",
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Does predation control adult sex ratios and longevities in marine pelagic copepods? / Hirst, A.G.; Bonnet, D.; Conway, D.V.P.; Kiørboe, Thomas.

In: Limnology and Oceanography, Vol. 55, No. 5, 2010, p. 2193-2206.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Does predation control adult sex ratios and longevities in marine pelagic copepods?

AU - Hirst, A.G.

AU - Bonnet, D.

AU - Conway, D.V.P.

AU - Kiørboe, Thomas

PY - 2010

Y1 - 2010

N2 - We assess the causes of adult sex ratio skew in marine pelagic copepods by examining changes in these ratios between the juveniles and adults, sexual differences in juvenile stage durations, and mortality rates of adults in the field and laboratory (when free from predators). In the field, late copepodite stages (CIV and CV) commonly have sex ratios that are either not significantly different from equity (1 : 1), or slightly male biased. By contrast, in adults, these ratios are commonly significantly biased toward female dominance. Sex ratio skews are therefore primarily attributable to processes in adults. Members of the non-Diaptomoidea have especially skewed adult ratios; in the members Oithonidae and Clausocalanidae this is not generated from differences between male and female adult physiological longevity (i.e., laboratory longevity when free of predators). In the genera Acartia, Oithona, and Pseudocalanus, we estimate that predation mortality contributed $ 69% of the field mortality rate in adult males, whereas in Acartia, Oithona, and Calanus adult females, this is $ 36%.We conclude that (1) adult sex ratio skew in pelagic copepods is primarily due to differential mortality of the sexes in the adult stage and not in juveniles, (2) mortality rates of adult Acartia, Pseudocalanus, and Oithona are dominated by predation mortality rather than physiological longevity (except under extreme food limitation), and (3) in Pseudocalanus and Oithona, elevated mortality rates in adult males to females is predominantly due to higher predation on males. Our work demonstrates that we now need to develop a more comprehensive understanding of the importance of feeding preferences in predators.

AB - We assess the causes of adult sex ratio skew in marine pelagic copepods by examining changes in these ratios between the juveniles and adults, sexual differences in juvenile stage durations, and mortality rates of adults in the field and laboratory (when free from predators). In the field, late copepodite stages (CIV and CV) commonly have sex ratios that are either not significantly different from equity (1 : 1), or slightly male biased. By contrast, in adults, these ratios are commonly significantly biased toward female dominance. Sex ratio skews are therefore primarily attributable to processes in adults. Members of the non-Diaptomoidea have especially skewed adult ratios; in the members Oithonidae and Clausocalanidae this is not generated from differences between male and female adult physiological longevity (i.e., laboratory longevity when free of predators). In the genera Acartia, Oithona, and Pseudocalanus, we estimate that predation mortality contributed $ 69% of the field mortality rate in adult males, whereas in Acartia, Oithona, and Calanus adult females, this is $ 36%.We conclude that (1) adult sex ratio skew in pelagic copepods is primarily due to differential mortality of the sexes in the adult stage and not in juveniles, (2) mortality rates of adult Acartia, Pseudocalanus, and Oithona are dominated by predation mortality rather than physiological longevity (except under extreme food limitation), and (3) in Pseudocalanus and Oithona, elevated mortality rates in adult males to females is predominantly due to higher predation on males. Our work demonstrates that we now need to develop a more comprehensive understanding of the importance of feeding preferences in predators.

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DO - 10.4319/lo.2010.55.5.2193

M3 - Journal article

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SP - 2193

EP - 2206

JO - Limnology and Oceanography

JF - Limnology and Oceanography

SN - 0024-3590

IS - 5

ER -