Trade-offs between offspring fitness and future reproduction of adult female black brent

1.?Successful reproduction requires numerous decisions, and some of which may require trade-offs between current and future reproduction. We studied effects of choice of foraging patches on gosling growth and future breeding by mothers in black brent (Branta bernicla nigricans) geese. 2.?Specific foraging areas consistently produced high-quality goslings over 21?years. We found a consistent ranking of gosling mass, corrected for age, across brood rearing areas (BRAs) and years [Akaike model weights, Σw(i) =?1·00 for models including additive effects of BRA and year]. Growth of goslings largely determines their future fitness, so areas where goslings grew most rapidly also produced goslings with the highest mean fitness. 3.?We used a multistate robust design capture-mark-recapture approach to estimate the probability of transitioning from a breeding state to a non-breeding (unobservable) state as a function of quality of BRA. 4.?In the best supported model, transition from a breeding state to a non-breeding state was positively related to gosling growth rates across BRAs. Thus, future reproduction was lower for females using BRAs that produced higher-quality goslings. Our results are consistent with trade-offs by individual brent between fitness of their current offspring and their own reproductive value.     

Female mate preference and offspring fitness in the melon fly

The influence of female mate preference on the fitness components of offspring was studied in the melon fly,Dacus cucurbitae. Adult flies were allowed to mate under two experimental treatments. In one treatment, 100 females and 100 males were allowed to mate freely in a cage (cage-mating). In the other treatment, a single female was allowed to mate with a single male in a small chamber (chamber-mating). Viability in the immature stages was not different between two treatments. The developmental speed of female offspring in the cage-mating treatment was faster than that in the chamber-mating treatment. The wing length of offspring of both sex in the cage-mating treatment was also larger than that in the chamber-mating treatment. These results were considered to support 3-trait handicap models of the evolution of female mate preference.     

The influence of a positive correlation between clutch size and offspring fitness on the optimal offspring size

Summary The effect is modeled of a positive relationship between clutch size and offspring fitness on the optimal investment in offspring. In species which meet the assumptions of the model, the model predicts a positive correlation between maternal resource level and offspring size. If larger mothers are able to allocate more resources to offspring, then the model would also predict a positive correlation between maternal size and offspring size when the assumptions of the model are met. Thus, this model may help explain both among and within individual variation in offspring size. When offspring are produced in groups and the number of offspring killed per clutch is limited by predator satiation, offspring in larger clutches may experience a higher probability of survival. Such a life style may be found in animals such as sea turtles. Offspring size is positively correlated with maternal size in some members of this group.     

Age-dependent inbreeding risk and offspring fitness costs in female black grouse

Dispersal is an important mechanism used to avoid inbreeding. However, dispersal may only be effective for part of an individual's lifespan since, post-dispersal individuals that breed over multiple reproductive events may risk mating with kin of the philopatric sex as they age. We tested this hypothesis in black grouse Tetrao tetrix, and show that yearling females never mated with close relatives whereas older females did. However, matings were not with direct kin suggesting that short-distance dispersal to sites containing kin and subsequent overlap of reproductive lifespans between males and females were causing this pattern. Chick mass was lower when kinship was high, suggesting important fitness costs associated with inbred matings. This study shows that increased inbreeding risk might be a widespread yet rarely considered cost of ageing.     

Positive correlation between vegetation dissimilarity and genetic differentiation of Carex sempervirens

Synthesizing genetic data at population level and vegetation data at community level may give insight into how ecological and evolutionary processes associated with different vegetation influence genetic diversity and differentiation of plant populations. We correlated population genetic patterns of Carex sempervirens with community vegetation patterns in abandoned subalpine grassland in the Swiss Alps. Within-population genetic diversity (percentage of polymorphic bands and Nei's gene diversity) of C. sempervirens was not significantly correlated with plant richness, evenness or Shannon's diversity index (Pearson correlation coefficient |r|<0.32, P>0.10). However, the genetic distance (F_ST) between C. sempervirens populations was significantly positively correlated with the vegetation dissimilarity between communities (Mantel's r=0.23, P<0.01). The correlation between the population genetic differentiation and the vegetation dissimilarity was not due to the parallel effects of geographic isolation or site conditions, because F_ST was not correlated with the geographic distance or the pairwise differences in any of the measured site condition parameters. One likely mechanism is that different plant communities were associated with different selective forces, which, in turn, influenced the genetic differentiation between C. sempervirens populations. Another possibility is that the vegetation heterogeneity (dissimilarity) generated ecological barriers against gene flow and thus enhanced the genetic differentiation between C. sempervirens populations.     

Females allocate differentially to offspring size and number in response to male effects on female and offspring fitness

Female investment in offspring size and number has been observed to vary with the phenotype of their mate across diverse taxa. Recent theory motivated by these intriguing empirical patterns predicted both positive (differential allocation) and negative (reproductive compensation) effects of mating with a preferred male on female investment. These predictions, however, focused on total reproductive effort and did not distinguish between a response in offspring size and clutch size. Here, we model how specific paternal effects on fitness affect maternal allocation to offspring size and number. The specific mechanism by which males affect the fitness of females or their offspring determines whether and how females allocated differentially. Offspring size is predicted to increase when males benefit offspring survival, but decrease when males increase offspring growth rate. Clutch size is predicted to increase when males contribute to female resources (e.g. with a nuptial gift) and when males increase offspring growth rate. The predicted direction and magnitude of female responses vary with female age, but only when per-offspring paternal benefits decline with clutch size. We conclude that considering specific paternal effects on fitness in the context of maternal life-history trade-offs can help explain mixed empirical patterns of differential allocation and reproductive compensation.     

Change of nipple preference between successive offspring in Japanese macaques

Selective use of nipples among free-ranging infant Japanese macaques (Macaca fuscata) was studied. Each infant held only one of its mother's two nipples in the mouth during an average of 90.9% ± 1.5% (SEM) of total nipple contact time. The next offspring born to the same mother tended to use the nipple that its previous sibling had not used. Maternal behavior did not cause use of one nipple or the other.     

Fine-scale genetic analysis of species-specific female preference in Drosophila simulans

Behavioural differences are thought to be the first components to contribute to species isolation, yet the precise genetic basis of behavioural isolation remains poorly understood. Here, we used a combination of behaviour assays and genetic mapping to provide the first refined map locating candidate genes for interspecific female preference isolating Drosophila simulans from D. melanogaster. First, we tested whether two genes identified as affecting D. melanogaster female intraspecific mate choice also affect interspecific mate choice; neither of these genes was found to contribute to species‐specific female preference. Next, we used deficiency mapping to locate genes on the right arm of the third chromosome for species‐specific female preference and identified five small significant regions that contain candidate genes contributing to behavioural isolation. All five regions were located in areas that would have low interspecific recombination, which mirrors the results of other behavioural isolation studies that used quantitative trait locus (QTL) mapping, but without the potential concern of bias towards regions of low recombination that QTL mapping may have. As this model system may be refined to the individual gene level using the same methodology, this initial map we provide may potentially serve as a ready template for the identification and characterization of the first behavioural isolation genes.     

The evolution of alternative reproductive strategies: fitness differential, heritability, and genetic correlation between the sexes

Paternity analyses using molecular markers have become standard in studies of mating systems, parentage, and kinship. In systems where individuals exhibit alternative mating strategies, molecular analyses have been productively used to estimate the reproductive success of each behavioral type and hence the fitness consequences to each individual. Here we review the fitness results in a system of five alternative mating strategies present in one population of side-blotched lizards (Uta stansburiana). Males in this population adopt one of three behavioral strategies that differ in their degree of territoriality and mate guarding. In contrast, females adopt one of two strategies that differ in offspring quantity and quality. We use paternity analyses to estimate the fitness of each morph, the heritability of reproductive strategy, and the correlation in strategy between the sexes and discuss the implications of our findings for the evolution and maintenance of reproductive polymorphism in this and other systems.     

No detectable genetic correlation between male and female mating frequency in the stalk-eyed fly Cyrtodiopsis dalmanni

There is much interest in explaining why female insects mate multiply. Females of the stalk-eyed fly Cyrtodiopsis dalmanni can mate several times each day in a lifetime which may span several months. There are many adaptive explanations, but one hypothesis that has received little rigorous empirical attention is that female multiple mating has evolved for non-adaptive reasons as a correlated response to selection for high male mating frequency rather than because of direct or indirect benefits accruing to females. We tested this hypothesis in stalk-eyed flies by measuring the mating frequency of females from lines that exhibited a direct response in males to artificial selection for increased ('high') and decreased ('low') male mating frequency. We found that the mating frequency of high-line females did not differ from that of low-line females. Hence, there was no support for a genetic correlation between male and female mating frequency in this species. Our study suggests that the genes which influence remating may not be the same in the sexes, and that females remate frequently in this species to gain as yet unidentified benefits.     

The relationship between host selection behaviour and offspring fitness in a koinobiont parasitoid

1. When host quality varies, optimal foraging theory assumes that parasitic wasps select hosts in a manner that increases their individual fitness. In koinobiont parasitoids, where the hosts continue developing for a certain period of time after parasitisation, host selection may not reflect current host quality but may be based on an assessment of future growth rates and resources available for the developing larvae. 2. When presented with hosts of uniform quality, the koinobiont parasitoid Leptomastix dactylopii exhibits a characteristic host‐selection behaviour: some hosts are accepted for oviposition on first encounter, while others are rejected several times before an egg is laid in them, a behaviour that is commonly associated with a changing host acceptance threshold during the course of a foraging bout. 3. The fitness of the offspring that emerged from hosts accepted immediately upon encounter was compared with the fitness of offspring emerged from hosts rejected several times before being accepted for oviposition. 4. The pattern of host acceptance and rejection was not related to any of the measured fitness parameters of the offspring emerging from these hosts (development time, size at emergence, sex ratio at emergence, and female offspring egg load). 5. While complex post facto adaptive explanations can be devised to explain the nature of such a time and energy consuming host selection process, it is suggested that physiological constraints on egg production or oviposition may provide an alternative, purely mechanistic, explanation for the results obtained.     

Migration and the genetic covariance between habitat preference and performance

Studies of the genetic covariance between habitat preference and performance have reported conflicting outcomes ranging from no covariance to strong covariance. The causes of this variability remain unclear. Here we show that variation in the magnitude of genetic covariance can result from variability in migration regimes. Using data from walking stick insects and a mathematical model, we find that genetic covariance within populations between host plant preference and a trait affecting performance on different hosts (cryptic color pattern) varies in magnitude predictably among populations according to migration regimes. Specifically, genetic covariance within populations is high in heterogeneous habitats where migration between populations locally adapted to different host plants generates nonrandom associations (i.e., linkage disequilibrium) between alleles at color pattern and host preference loci. Conversely, genetic covariance is low in homogeneous habitats where a single host exists and migration between hosts does not occur. Our results show that habitat structure and patterns of migration can strongly affect the evolution and variability of genetic covariance within populations.     

Georgian and kurd mtDNA sequence analysis shows a lack of correlation between languages and female genetic lineages

Mitochondrial DNA sequences from Georgians and Kurds were analyzed in order to test the possible correlation between female lineages and languages in these two neighboring West Eurasian groups. Mitochondrial sequence pools in both populations are very similar despite their different linguistic and prehistoric backgrounds. Both populations present mtDNA lineages that clearly belong to the European gene pool, as shown by 1) similar nucleotide and sequence diversities; 2) a large number of sequences shared with the rest of European samples; 3) nonsignificant genetic distances; and 4) classification of the present lineages into the major European mtDNA haplogroups already described. The outlier position of the populations from the Caucasus according to classical genetic markers is not recognized in the present Georgian mtDNA sequence pool. This result suggests that the differentiation of mtDNA sequences in West Eurasia and the outlier features of Caucasian populations should be attributed to different processes. Moreover, the putative linguistic relationship between Caucasian groups and the Basques, another outlier population within Europe for classical genetic markers, is not detected by the analysis of mtDNA sequences.     

Testing the fisherian mechanism: examining the genetic correlation between male song and female response in waxmoths

Models of indirect (genetic) benefits sexual selection predict linkage disequilibria between genes that influence male traits and female preferences, owing to either non-random mate choice or physical linkage. Such linkage disequilibria, a genetic correlation, can accelerate the evolution of male traits and female preferences to exaggerated levels. But relatively few empirical studies have measured the genetic correlation between male traits and female responses in natural populations, and the findings of those few are mixed: often, genetic correlations are not found. We tested the above prediction in an acoustic pyralid moth, Achroia grisella, in which males attract females with a rhythmic train of sound pulses, and females respond only to song that exceeds a minimum pulse rhythm. Both male song rhythm and female threshold response are repeatable and heritable characters. Because female choice in A. grisella is based largely on male song, and males do not appear to provide direct benefits at mating, genetic correlation between male song rhythm and female response is expected. We studied 2 A. grisella populations, bred them according to a full-sib/half-sib design, split the progeny among 4 different environmental conditions, and measured the male song/female response genetic correlation in each of the 8 resulting groups. While song rhythm and response threshold were generally heritable, we found no evidence of significant genetic correlation between these traits. We suggest that the complexity of the various male song characters, of female response to male song, and of correlations between male song characters and between aspects of female response have mitigated the evolution of strong genetic correlation between song and response. Thus, exaggerated levels of trait development may be tempered.