scholarly journals Sex differences in biochemical composition, energy content and allocation to reproductive effort in the brooding sea star Leptasterias polaris

2004 ◽  
Vol 283 ◽  
pp. 179-190 ◽  
Author(s):  
JF Raymond ◽  
JH Himmelman ◽  
HE Guderley
Keyword(s):  
Sex Differences ◽  
Biochemical Composition ◽  
Reproductive Effort ◽  
Energy Content ◽  
Sea Star ◽  
Leptasterias Polaris

Freshwater Migration as a Determinant Factor in the Somatic Cost of Reproduction of Two Anadromous Coregonines of James Bay

1990 ◽  
Vol 47 (2) ◽  
pp. 318-334 ◽  
Author(s):  
Yvan Lambert ◽  
Julian J. Dodson
Keyword(s):  
Energy Cost ◽  
Reproductive Effort ◽  
Energy Content ◽  
Cost Of Reproduction ◽  
Energy Gain ◽  
Lake Whitefish ◽  
James Bay ◽  
Energy Increase ◽  
Species Specific ◽  
Somatic Energy

We tested the hypothesis that the species-specific costs of migration differentially affect reproductive effort and somatic cost of reproduction in sympatric anadromous populations of cisco (Coregonus artedii) and lake whitefish (C. clupeaformis) of James Bay. Reproductive effort, which includes the energy cost of migration, is higher for cisco. Female cisco allocate more energy to reproduction than its total energy gain. The energy invested by lake whitefish in reproduction is approximately equal to its seasonal energy gain. Reproduction results in large differences in the energy content of gonads, viscera, and carcass between reproductive and nonreproductive fish of the same length. Neither cisco nor lake whitefish are able to spawn two years in succession. The somatic energy increase of reproductive female cisco is 121% lower than the somatic energy increase of nonreproductive females; similar comparisons are 89% (female) and 103% (male) for lake whitefish. The energy cost of migration is largely responsible for the higher somatic cost of reproduction observed for cisco. These different somatic costs of migration are related to resource accumulation prior to migration and to differences in the aerobic cost of swimming between the two species in combination with the difficulty of the freshwater migration.

Localization of infaunal prey by the sea star Leptasterias polaris

2004 ◽  
Vol 146 (5) ◽  
pp. 887-894 ◽  
Author(s):  
Myles Thompson ◽  
David Drolet ◽  
John H. Himmelman
Keyword(s):  
Sea Star ◽  
Leptasterias Polaris

scholarly journals Sex differences in lizard escape decisions vary with latitude, but not sexual dimorphism

2015 ◽  
Vol 282 (1805) ◽  
pp. 20150050 ◽  
Author(s):  
Diogo S. M. Samia ◽  
Anders Pape Møller ◽  
Daniel T. Blumstein ◽  
Theodore Stankowich ◽  
William E. Cooper
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Risk Taking ◽  
Reproductive Effort ◽  
Meta Analysis ◽  
Specific Behaviour ◽  
Underlying Mechanisms ◽  
Natural And Sexual Selection ◽  
Predator Behaviour ◽  
Latitudinal Effect

Sexual selection is a powerful evolutionary mechanism that has shaped the physiology, behaviour and morphology of the sexes to the extent that it can reduce viability while promoting traits that enhance reproductive success. Predation is one of the underlying mechanisms accounting for viability costs of sexual displays. Therefore, we should expect that individuals of the two sexes adjust their anti-predator behaviour in response to changes in predation risk. We conducted a meta-analysis of 28 studies (42 species) of sex differences in risk-taking behaviour in lizards and tested whether these differences could be explained by sexual dichromatism, by sexual size dimorphism or by latitude. Latitude was the best predictor of the interspecific heterogeneity in sex-specific behaviour. Males did not change their escape behaviour with latitude, whereas females had increasingly reduced wariness at higher latitudes. We hypothesize that this sex difference in risk-taking behaviour is linked to sex-specific environmental constraints that more strongly affect the reproductive effort of females than males. This novel latitudinal effect on sex-specific anti-predator behaviour has important implications for responses to climate change and for the relative roles of natural and sexual selection in different species.

scholarly journals Sex differences in the effects of juvenile and adult diet on age-dependent reproductive effort

2015 ◽  
Vol 28 (5) ◽  
pp. 1067-1079 ◽  
Author(s):  
T. M. Houslay ◽  
J. Hunt ◽  
M. C. Tinsley ◽  
L. F. Bussière
Keyword(s):  
Sex Differences ◽  
Reproductive Effort ◽  
Age Dependent ◽  
Adult Diet

Energy budgets and reproductive ecologies of mayflies occupying disparate thermal environments

1989 ◽  
Vol 67 (11) ◽  
pp. 2782-2791 ◽  
Author(s):  
Michael J. Benton
Keyword(s):  
Body Size ◽  
Reproductive Effort ◽  
Energy Content ◽  
Aquatic Insect ◽  
Handling Time ◽  
Growth Efficiency ◽  
Life Cycles ◽  
Energy Budgets ◽  
Insect Larvae ◽  
Growth Ratio

Energy budgets were calculated for two populations of Ameletus occupying thermally disparate habitats. Growth, consumption, respiration, fecundity, and energy content of larvae and eggs were determined experimentally. Respiration rates increased and decreased with temperature throughout the life cycles of both species, although thermal effects became less pronounced with increased body size. Ameletus similior exhibited more uniform and consistently higher respiration values than Ameletus celer. Respiration costs were not constant over the life cycle of either species as has been reported for some other mayflies. Growth was influenced by both temperature (which affected instar duration) and body size (which affected growth ratio). Growth corresponded positively to temperature in both species, but was more uniform in A. celer. Net growth efficiency and assimilation were highest during cold periods in A. celer, but highest during warmer periods in A. similior. Consumption estimates were high even after adjustments for projected nonfeeding time, but unless food availability or handling time is limiting, the feeding rate of Ameletus relative to body mass may be higher than rates reported for other aquatic insect larvae. Several sources of error in consumption estimates existed, however. Assimilation efficiencies were low, but comparable to those for other herbivorous aquatic insects. Reproductive effort was higher in A. celer, but net reproductive effort was lower. The higher net reproductive effort by A. similior did not result in increased fecundity as expected, but in higher egg energy content. This and other factors suggest that A. similior displays more "K-selected" traits than A. celer, and indicates that greater fitness may not necessarily be synonymous with higher fecundity in all mayflies in all habitats.

Dendrogaster (Crustacea: Ascothoracida) parasitic in Alaskan and eastern Canadian Leptasterias (Asteroidea)

1986 ◽  
Vol 64 (6) ◽  
pp. 1249-1253 ◽  
Author(s):  
Mark J. Grygier
Keyword(s):  
Bering Sea ◽  
Western Hemisphere ◽  
Sea Star ◽  
Bristol Bay ◽  
Eastern Bering Sea ◽  
Middle Piece ◽  
Davis Strait ◽  
Leptasterias Polaris

The ascothoracid parasite Dendrogaster is reported from four boreal localities in the Western Hemisphere. Dendrogaster elegans Wagin infests the sea star Leptasterias polaris in Bristol Bay, Alaska, and in the Gulf of St. Lawrence; the eastern specimens have a shorter brood sac middle piece. A lectotype is selected and described for D. arctica Korschelt from L. groenlandica in the eastern Bering Sea; Siberian specimens previously assigned to this species differ from the type in many details. Immature specimens of an unidentified Dendrogaster species have been found in L. floccosa from the Davis Strait.

Biochemical composition, energy content and chemical antifeedant and antifoulant defenses of the colonial Antarctic ascidian Distaplia cylindrica

2004 ◽  
Vol 145 (5) ◽  
pp. 885-894 ◽  
Author(s):  
J. B. McClintock ◽  
M. O. Amsler ◽  
C. D. Amsler ◽  
K. J. Southworth ◽  
C. Petrie ◽  
...  
Keyword(s):  
Biochemical Composition ◽  
Energy Content

Reproduction in Australian elapid snakes II. Female reproductive cycles

1977 ◽  
Vol 25 (4) ◽  
pp. 655 ◽  
Author(s):  
R Shine
Keyword(s):  
Reproductive Effort ◽  
Placental Transfer ◽  
Energy Content ◽  
Late Summer ◽  
Egg Laying ◽  
Published Data ◽  
Maternal Size ◽  
Wet Weight ◽  
Reproductive Cycles ◽  
Second Clutch

Female reproductive cycles were studied in seven species of Australian elapid snakes, and the results compared with published information on snake faunas of other continents. Of the species studied, five are live-bearing (Austrelaps superbus, Hemiaspis signata, Notechis scutatus, Pseudechis porphyriacus and Unechis gouldii) and two egg-laying (Pseudonaja nuchalis and P. textilis). The live-bearing species usually produce one clutch per year, a higher reproductive frequency than has been found in most previously studied venomous snakes. All live-bearing species show similar seasonal timing of ovulation and parturition. Gestation occupies about 14 weeks. The egg-laying species ovulate at about the same time as sympatric live-bearers, but oviposit shortly thereafter and may produce a second clutch of eggs in late summer. P. porphyriacus shows true 'viviparity', including placental transfer of nutrients (ash content of oocytes increases during gestation, energy content decreases only slightly). The live (wet) weight of the oocytes increases up to fourfold during gestation in live-bearing species, but dry weights change very little. Extra-uterine transfer of oocytes is common. Infertility is rare in A. superbus and P. porphyriacus, but frequent in N. scutatus. Clutch size is correlated with maternal body size in all species. The ratio of clutch weight to body weight decreased slightly with increasing maternal size in N. scutatus and P. porphyriacus. Published data on reptilian 'reproductive effort' are reviewed.

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