Hatching Asynchrony and Feeding Rates in Yellow Warblers: A Test of the Sexual Conflict Hypothesis

1993 ◽  
Vol 142 (5) ◽  
pp. 881-892 ◽  
Author(s):  
Percy N. Hebert ◽  
Spencer G. Sealy
2019 ◽  
Vol 116 (17) ◽  
pp. 8437-8444 ◽  
Author(s):  
Brian Hollis ◽  
Mareike Koppik ◽  
Kristina U. Wensing ◽  
Hanna Ruhmann ◽  
Eléonore Genzoni ◽  
...  

In many animals, females respond to mating with changes in physiology and behavior that are triggered by molecules transferred by males during mating. InDrosophila melanogaster, proteins in the seminal fluid are responsible for important female postmating responses, including temporal changes in egg production, elevated feeding rates and activity levels, reduced sexual receptivity, and activation of the immune system. It is unclear to what extent these changes are mutually beneficial to females and males or instead represent male manipulation. Here we use an experimental evolution approach in which females are randomly paired with a single male each generation, eliminating any opportunity for competition for mates or mate choice and thereby aligning the evolutionary interests of the sexes. After >150 generations of evolution, males from monogamous populations elicited a weaker postmating stimulation of egg production and activity than males from control populations that evolved with a polygamous mating system. Males from monogamous populations did not differ from males from polygamous populations in their ability to induce refractoriness to remating in females, but they were inferior to polygamous males in sperm competition. Mating-responsive genes in both the female abdomen and head showed a dampened response to mating with males from monogamous populations. Males from monogamous populations also exhibited lower expression of genes encoding seminal fluid proteins, which mediate the female response to mating. Together, these results demonstrate that the female postmating response, and the male molecules involved in eliciting this response, are shaped by ongoing sexual conflict.


1999 ◽  
Vol 77 (4) ◽  
pp. 515-523 ◽  
Author(s):  
Percy N Hébert ◽  
Raymond McNeil

We examined predictions derived from three hypotheses (hurry-up, peak-load reduction, and brood reduction) regarding the adaptive significance of hatching asynchrony. The study was conducted, in 1991 and 1992, in a colony of Ring-billed Gulls (Larus delawarensis) on l'île de la Couvée, Montréal, Québec, Canada. The hypotheses were examined by comparing the mass and size of 18- to 20-day-old chicks from broods that hatched asynchronously (unmanipulated) and synchronously (manipulated). We also compared feeding rates and fledging success between asynchronous and synchronous broods. Also, in 1992, a sample of asynchronous and synchronous broods was experimentally food stressed by providing them with an additional chick when the oldest resident chick was 4 or 5 days old. Consistent with the hurry-up hypothesis, hatch spreads were significantly shorter in 1991 when the mean clutch initiation date was significantly earlier compared with 1992. Also consistent with the hypothesis, hatch spreads increased significantly through the breeding season. In agreement with the peak-load-reduction hypothesis, feeding rates were significantly lower in asynchronous broods compared with synchronous broods. Contrary to the hypothesis, however, the feeding rate was similar for food-stressed asynchronous and food-stressed synchronous broods. As predicted by the brood-reduction hypothesis, survivorship was higher for first-hatched chicks in asynchronous broods compared with chicks in synchronous broods. Total brood loss as a result of starvation tended to occur less often in asynchronous broods compared with synchronous broods. Likewise, fledging success was higher in asynchronous broods compared with synchronous broods. However, contrary to the brood-reduction hypothesis, survival rate of first-hatched chicks, total brood loss, and fledging success were similar in food-stressed asynchronous and synchronous broods. The above results indicate that several benefits accure to Ring-billed Gulls from hatching asynchrony.


1993 ◽  
Vol 24 (1) ◽  
pp. 10 ◽  
Author(s):  
Percy N. Hebert ◽  
Spencer G. Sealy

Behaviour ◽  
2005 ◽  
Vol 142 (11-12) ◽  
pp. 1495-1514 ◽  
Author(s):  
Tudor I. Draganoiu ◽  
Laurent Nagle ◽  
Raphael Musseau ◽  
Michel Kreutzer

AbstractSexual conflict over parental care can be mediated through differences in male and female overall feeding rates, brood division or both. At present, it is not clear whether post-fledging brood division occurs due to sexual conflict over parental investment or is due to bi-parental cooperation, e.g. increase offspring fitness. We provide evidence suggesting that brood division in the black redstart, Phoenicurus ochruros is due to sexual conflict. Males and females had similar feeding contributions during the nestling stage, which is common for most passerine species. After fledging, each parent showed long-term feeding preferences for particular chicks within the brood. In most cases (74%; 17/23) both parents provided care but males tended to feed less fledglings than females did and in about a quarter of cases (26%; 6/23) females fed the whole brood by themselves. The relative amount of male to female post-fledging feedings showed a significant negative relationship with the proportion of fledglings cared for exclusively by the male. These results suggest (1) a close link between the amount of parental care and brood division; (2) sexual conflict can be mediated through brood division; (3) female redstarts appear to loose this conflict more often than male redstarts, with in the extreme cases males showing post-fledging brood desertion. A literature review shows brood division to occur in at least a dozen of songbird species but male black redstarts have the lowest relative post-fledging parental investment, expressed either as feeding rates or number of chicks in care.


1991 ◽  
Vol 69 (3) ◽  
pp. 661-668 ◽  
Author(s):  
Ralph D. Morris ◽  
Michelle Woulfe ◽  
G. D. Wichert

In 1987 and 1988, common tern (Sterna hirundo) chicks at a colony near Port Colborne, Ontario, were individually colour banded according to known hatch order. Intraclutch hatch intervals produced size disparities among chicks at brood completion; third-hatched chicks were significantly lighter and at a significant survival disadvantage compared with their earlier-hatched siblings. There were differences in feeding rates according to hatch order and many third-hatched chicks obtained fewer or no feedings during our periods of observation. Sixty-five chicks known to have abandoned their home broods gained acceptance into foreign broods. Chicks that remained in the foreign brood for more than 2 days (average residency 11.9 ± 5.3 days; n = 26) were fed and brooded by the foster parents, were on average older than the youngest resident chick, but were not always the last hatched in their home brood. Conversely, chicks that were in a foreign brood for less than 2 days were no different in age from the youngest resident chick. Survival and fledging success was highest for chicks accepted into two chick broods in which they were older than the resident second chick; in effect, the adoptee became the second chick. Parents that accepted a foreign chick for more than 2 days experienced a seasonal fitness loss compared with nonadopting parents. As the only viable option available to them, selection favours movement away from home broods by chicks that may be disadvantaged there.


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