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.
U2 - 10.4319/lo.2010.55.5.2193
DO - 10.4319/lo.2010.55.5.2193
M3 - Journal article
SN - 0024-3590
VL - 55
SP - 2193
EP - 2206
JO - Limnology and Oceanography
JF - Limnology and Oceanography
IS - 5
ER -