Sex-specific costs of hatching last: an experimental study on herring gulls (Larus argentatus)

Abstract

An organism's pattern of development can have important long-term fitness effects. In species where the sexes differ in size or other phenotypic traits, they may also have different optimal developmental rates. This influences both parental sex allocation strategies and susceptibility of the sexes to early developmental conditions. However, sex differences in developmental rate and vulnerability to environment during the embryonic period are not well understood. In birds, sibling competition and hatching asynchrony may select for accelerated embryonic development of the last offspring in order to reduce their competitive disadvantage after hatching. They may advance their hatching in response to vocal stimuli by the older siblings. It is, however, unclear whether this flexibility in developmental rates is sex specific. In this study, we experimentally manipulated between-embryo contact and tested whether this affected the pre-natal developmental rate and post-hatching performance of male and female offspring from last-laid eggs in the herring gull. Post-hatching performance was measured both in competitive and noncompetitive situations. Among young incubated in isolation, males hatched faster than females, but both sexes fledged in similar, relatively good condition. Among young incubated with normal between-embryo contact, hatching time did not differ between sexes, but males fledged in poorer condition than females, regardless of whether they were reared singly or in a brood. These results suggest that male and female offspring differ in their ability to mitigate the costs of hatching asynchrony.

Effect of Thermal Embryonic Manipulation on the Quality of Male and Female Broiler Meat Submitted to Thermal Stress Pre-Slaughter

“…It is known that male broilers are more vulnerable to environmental changes than females (Bogdanova & Nager, 2008). However, in the present trial, the meat quality of neither male or female broilers was affected by the high incubation temperature applied during the sensitive period of embryonic thermoregulatory system development.…”

Influence of temperature stimulation during the last 4 days of incubation on secondary sex ratio and later performance in male and female broiler chicks

“…But the clearest sign of the improved vitality of the hatched chicks seems to be the increased proportion of hatched male chicks in relation to all hatched chicks after short-term warm stimulation, which was shown in all 6 trials. It is known that male embryos or foetuses are more vulnerable to environmental changes than the females (Bogdanova and Nager, 2008;Catalano et al, 2008). Related to this fact, our hypothesis is that prenatal ''temperature training'' with shortterm warm loads induced an improvement in vitality, especially in the male late-term embryos, and at least for the male hatchlings.…”

Persistent sex‐by‐environment effects on offspring fitness and sex‐ratio adjustment in a wild bird population

“…Thus, the morphological development and fitness of offspring may vary sex‐specifically across a range of rearing conditions, and some effects may be manifested later in life (see also McDonald, Olsen & Cockburn ; Berthouly et al . ; Bogdanova & Nager ; Boncoraglio, Martinelli & Saino ; Bonisoli‐Alquati et al . ; Sockman et al .…”