scholarly journals Actuarial senescence in a dimorphic bird: different rates of ageing in morphs with discrete reproductive strategies

2018 ◽  
Vol 285 (1892) ◽  
pp. 20182053 ◽  
Author(s):  
Melissa L. Grunst ◽  
Andrea S. Grunst ◽  
Vincent A. Formica ◽  
Marisa L. Korody ◽  
Adam M. Betuel ◽  
...  
Keyword(s):  
Parental Care ◽  
Parental Investment ◽  
Parental Support ◽  
Alternative Hypothesis ◽  
Mating Strategies ◽  
Competitive Strategies ◽  
Zonotrichia Albicollis ◽  
Sexual Competition ◽  
Senescence Rate ◽  
Genetically Determined

It is often hypothesized that intra-sexual competition accelerates actuarial senescence, or the increase in mortality rates with age. However, an alternative hypothesis is that parental investment is more important to determining senescence rates. We used a unique model system, the white-throated sparrow ( Zonotrichia albicollis ), to study variation in actuarial senescence. In this species, genetically determined morphs display discrete mating strategies and disassortative pairing, providing an excellent opportunity to test the predictions of the above hypotheses. Compared to tan-striped males, white-striped males are more polygynous and aggressive, and less parental. Tan-striped females receive less parental support, and invest more into parental care than white-striped females, which are also more aggressive. Thus, higher senescence rates in males and white-striped birds would support the intra-sexual competition hypothesis, whereas higher senescence rates in females and tan-striped birds would support the parental investment hypothesis. White-striped males showed the lowest rate of actuarial senescence. Tan-striped females had the highest senescence rate, and tan-striped males and white-striped females showed intermediate, relatively equal rates. Thus, results were inconsistent with sexual selection and competitive strategies increasing senescence rates, and instead indicate that senescence may be accelerated by female-biased parental care, and lessened by sharing of parental duties.

scholarly journals Why is mutual mate choice not the norm? Operational sex ratios, sex roles and the evolution of sexually dimorphic and monomorphic signalling

2002 ◽  
Vol 357 (1419) ◽  
pp. 319-330 ◽  
Author(s):  
H. Kokko ◽  
R. A. Johnstone
Keyword(s):  
Mate Choice ◽  
Parental Care ◽  
Parental Investment ◽  
Sex Roles ◽  
Mating Strategies ◽  
Operational Sex Ratio ◽  
Encounter Rate ◽  
Theoretic Model ◽  
Biparental Care ◽  
Mutual Mate Choice

Biases in the operational sex ratio (OSR) are seen as the fundamental reason behind differential competition for mates in the two sexes, and as a strong determinant behind differences in choosiness. This view has been challenged by Kokko and Monaghan, who argue that sex–specific parental investment, mortalities, mate–encounter rates and quality variation determine the mating system in a way that is not reducible to the OSR. We develop a game–theoretic model of choosiness, signalling and parental care, to examine (i) whether the results of Kokko and Monaghan remain robust when its simplifying assumptions are relaxed, (ii) how parental care coevolves with mating strategies and the OSR and (iii) why mutual mate choice is observed relatively rarely even when both sexes vary in quality. We find qualitative agreement with the simpler approach: parental investment is the primary determinant of sex roles instead of the OSR, and factors promoting choosiness are high species–specific mate–encounter rate, high sex–specific mate–encounter rate, high cost of breeding (parental investment), low cost of mate searching and highly variable quality of the opposite sex. The coevolution of parental care and mating strategies hinders mutual mate choice if one parent can compensate for reduced care by the other, but promotes it if offspring survival depends greatly on biparental care. We argue that the relative rarity of mutual mate choice is not due to biases in the OSR. Instead, we describe processes by which sexual strategies tend to diverge. This divergence is prevented, and mutual mate choice maintained, if synergistic benefits of biparental care render parental investment both high and not too different in the two sexes.

Mating strategies, parental investment and mutual ornamentation in Iberian Rock Sparrows (Petronia petronia)

Behaviour ◽  
2013 ◽  
Vol 150 (14) ◽  
pp. 1641-1663 ◽  
Author(s):  
Vicente García-Navas ◽  
Amanda García del Rincón ◽  
Esperanza S. Ferrer ◽  
Hicham Fathi
Keyword(s):  
Parental Care ◽  
Parental Investment ◽  
Paternal Care ◽  
Bird Species ◽  
Mating Strategies ◽  
Social Environments ◽  
Social Monogamy ◽  
Uniparental Care ◽  
Female Ornamentation ◽  
Brood Desertion

Relatively few bird species show complex social mating systems whose preponderance in a population is likely to affect the patterns of parental care observed there. In turn, parental investment is likely to be related to the expression of certain ornaments, which may reveal information on the bearer’s individual quality. Here we address both issues in a species characterised by several forms of parental care (both biparental and uniparental care) and in which both sexes possess a yellow breast patch, the rock sparrow (Petronia petronia). In our population, males contributed more to the care of the young in comparison with other populations. Social monogamy was the most frequent mating pattern and the percentage of cases of female (or male) brood desertion was lower with respect to that reported in previous studies, suggesting a flexible behaviour of this species to deal with different social environments. Birds did not pair assortatively with respect to the size of the yellow breast patch and we found no significant relationship between this trait and the frequency with which parents provisioned their chicks. However, we observed a positive relationship between male yellow patch size and nestling tarsus length, which suggests that more ornamented males are better parents. Males, but not females, differentially allocated parental investment in response to female ornamentation, although the benefits that males may gain from choosing more attractive females remain unidentified. Our results on paternal care investment along with previous studies on this species, reinforcing the view that the rock sparrow constitutes a good model to study sexual conflict over parental care under different social environments.

Are parental care trade-offs in shorebirds driven by parental investment or sexual selection?

2009 ◽  
Vol 22 (4) ◽  
pp. 672-682 ◽  
Author(s):  
V. A. OLSON ◽  
T. J. WEBB ◽  
R. P. FRECKLETON ◽  
T. SZÉKELY
Keyword(s):  
Sexual Selection ◽  
Parental Care ◽  
Parental Investment ◽  
Trade Offs

scholarly journals Sex-biased immunity is driven by relative differences in reproductive investment

2014 ◽  
Vol 281 (1790) ◽  
pp. 20140333 ◽  
Author(s):  
Crystal M. Vincent ◽  
Darryl T. Gwynne
Keyword(s):  
Immune Response ◽  
Sex Differences ◽  
Immune System ◽  
Sexual Dimorphism ◽  
Parental Investment ◽  
Sex Role ◽  
Reproductive Investment ◽  
Paternal Investment ◽  
Sexual Competition ◽  
Relative Differences

Sex differences in immunity are often observed, with males generally having a weaker immune system than females. However, recent data in a sex-role-reversed species in which females compete to mate with males suggest that sexually competitive females have a weaker immune response. These findings support the hypothesis that sexual dimorphism in immunity has evolved in response to sex-specific fitness returns of investment in traits such as parental investment and longevity, but the scarcity of data in sex-reversed species prevents us from drawing general conclusions. Using an insect species in which males make a large but variable parental investment in their offspring, we use two indicators of immunocompetence to test the hypothesis that sex-biased immunity is determined by differences in parental investment. We found that when the value of paternal investment was experimentally increased, male immune investment became relatively greater than that of females. Thus, in this system, in which the direction of sexual competition is plastic, the direction of sex-biased immunity is also plastic and appears to track relative parental investment.

scholarly journals Simultaneous GPS-tracking of parents reveals a similar parental investment within pairs, but no immediate co-adjustment on a trip-to-trip basis

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Marwa M. Kavelaars ◽  
Jan M. Baert ◽  
Jolien Van Malderen ◽  
Eric W. M. Stienen ◽  
Judy Shamoun-Baranes ◽  
...  
Keyword(s):  
Parental Care ◽  
Parental Investment ◽  
Time Frame ◽  
Gps Tracking ◽  
Nest Attendance ◽  
Time Intervals ◽  
Foraging Effort ◽  
Levels Of Care ◽  
Larus Fuscus ◽  
Underlying Processes

Abstract Background Parental care benefits the offspring, but comes at a cost for each parent, which in biparental species gives rise to a conflict between partners regarding the within-pair distribution of care. Pair members could avoid exploitation by efficiently keeping track of each other’s efforts and coordinating their efforts. Parents may, therefore, space their presence at the nest, which could also allow for permanent protection of the offspring. Additionally, they may respond to their partner’s previous investment by co-adjusting their efforts on a trip-to-trip basis, resulting in overall similar parental activities within pairs. Methods We investigated the coordination of parental care measured as nest attendance and foraging effort in the Lesser black-backed gull (Larus fuscus), a species with long nest bouts that performs extended foraging trips out of sight of their partner. This was achieved by GPS-tracking both pair members simultaneously during the entire chick rearing period. Results We found that the timing of foraging trips (and hence nest attendance) was coordinated within gull pairs, as individuals left the colony only after their partner had returned. Parents did not match their partner’s investment by actively co-adjusting their foraging efforts on a trip-by-trip basis. Yet, pair members were similar in their temporal and energetic investments during chick rearing. Conclusion Balanced investment levels over a longer time frame suggest that a coordination of effort may not require permanent co-adjustment of the levels of care on a trip-to-trip basis, but may instead rather take place at an earlier stage in the reproductive attempt, or over integrated longer time intervals. Identifying the drivers and underlying processes of coordination will be one of the next necessary steps to fully understand parental cooperation in long-lived species.

scholarly journals Lonely hearts or sex in the city? Density-dependent effects in mating systems

2006 ◽  
Vol 361 (1466) ◽  
pp. 319-334 ◽  
Author(s):  
Hanna Kokko ◽  
Daniel J Rankin
Keyword(s):  
Sexual Selection ◽  
Mate Choice ◽  
Parental Care ◽  
Mating Systems ◽  
Sex Role ◽  
Mate Guarding ◽  
Mating Strategies ◽  
Male Mating ◽  
Density Dependent ◽  
Basic Ideas

Two very basic ideas in sexual selection are heavily influenced by numbers of potential mates: the evolution of anisogamy, leading to sex role differentiation, and the frequency dependence of reproductive success that tends to equalize primary sex ratios. However, being explicit about the numbers of potential mates is not typical to most evolutionary theory of sexual selection. Here, we argue that this may prevent us from finding the appropriate ecological equilibria that determine the evolutionary endpoints of selection. We review both theoretical and empirical advances on how population density may influence aspects of mating systems such as intrasexual competition, female choice or resistance, and parental care. Density can have strong effects on selective pressures, whether or not there is phenotypic plasticity in individual strategies with respect to density. Mating skew may either increase or decrease with density, which may be aided or counteracted by changes in female behaviour. Switchpoints between alternative mating strategies can be density dependent, and mate encounter rates may influence mate choice (including mutual mate choice), multiple mating, female resistance to male mating attempts, mate searching, mate guarding, parental care, and the probability of divorce. Considering density-dependent selection may be essential for understanding how populations can persist at all despite sexual conflict, but simple models seem to fail to predict the diversity of observed responses in nature. This highlights the importance of considering the interaction between mating systems and population dynamics, and we strongly encourage further work in this area.

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