Terms Of Reproductive Success Research Articles

Song strophe‐length and reproductive success in a non‐passerine bird, the Hoopoe Upupa epops

HoopoeUpupa epopsmales produce a very simple song, with a repertoire size of one, in which the main difference between different strophes of a male and between the songs of different males is the number of elements they include (strophe‐length). In several passerine species it has been shown that strophe‐length is a sexually selected trait that reflects male quality and correlates with reproductive success. Here we analyse whether in a non‐passerine, the Hoopoe, strophe‐length of males is correlated with several variables of their reproductive success. Females paired with males singing long strophes laid their first clutch earlier, produced larger first clutches and laid second clutches after a successful first one more frequently than those paired with males singing short strophes. Moreover, males with long strophes produced more fledglings in their first clutches and in the whole season, partly because they brought more food for the brood than males with short strophes. The relationships found are not mediated by age effects. Previously we have shown that Hoopoe females in the early spring are attracted preferentially to songs with long strophes. Here we show that males singing long strophes also obtain postpairing benefits in terms of reproductive success, and that females paired with these males obtain direct benefits because these males provide greater feeding effort in the second half of the nestling period. These findings support the hypothesis that in the Hoopoe, strophe‐length is a sexually selected cue under direct selection.

Significance of Aggression for Hominoid Evolution

A principal component analysis of the correlation matrix array 25 items concerning the status of adult male and female as well as of offspring in 108 societies revealed that the more polygynous the society is, the more aggressive adult males in society are toward adult females. The more the subsistence of a society is dependent on the labor of males, the more aggressive adults are towards offspring. Swaddling and infanticide are considered to work as that buffering the aggression and to simultaneously act as a r-strategy or a K-strategy, respectively, in terms of reproductive success in human societies. Overall high level of aggression in greate apes and humans is discussed in terms of possible dietary changes that have occurred to produce high sociability in primates.

Relationships between individual- and population-based plankton models

Two simulations of plankton dynamics are combined: an N/P/Z model and an optimal foraging strategy dependent on variable vertical migration. We show that there is no optimal individual strategy consistent with a copepod population that has two generations and is a significant grazer on its limiting food supply. Alternative roles for diel vertical migration are considered. Introduction The purpose of this paper is to combine two different approaches to plankton modelling: one from the population perspective, the other from that of the individual. The interactions and inconsistencies between these two models will be considered in terms of their underlying assumptions as well as the technical methods used. Traditional nutrient, phytoplankton, zooplankton (N/P/Z) simulations treat P and Z as single entities. Usually there is no formal optimizing procedure, but a process of first defining the physical context, then selecting functional relationships and finally choosing parameter values. The results are judged by comparison with observations of, say, chlorophyll or zooplankton biomass. 'Tuning' is done by varying the least known (or knowable) parameters, such as predation rate (e.g. Fasham et ai, 1990). A previous paper (Steele and Henderson, 1998) used this approach in a vertically structured model with diel migration dependent on vertically varying light and food concentration, and on predator density. The responses were assessed in terms of reproductive success at diapause. Different patterns of vertical migration did not appear to produce significant changes at diapause after two generations. An alternative approach is to define explicitly an optimal strategy that the individual plankter should follow. The favoured criteria involve life-time reproductive success for strategies such as acquiring food and avoiding predation. A popular method, dynamic programming, involves back calculation over the life cycle of the selected species (Mangel and Clark, 1988). This 'backward' method is necessary when the optimal condition, maximum reproductive output, is only defined at the end of the forward simulation. Each type of simulation will be used, with the common critical variable being the diel vertical migration (DVM) of a calanoid copepod species. The population model will be run forward in time to determine food and predator concentrations. The individual-based model can be run backwards using these concentrations to define the optimal migration strategy. This strategy can then be used for a further run of the population model. Should this iterative process lead to convergence? If not, is this due to technical inadequacies in the models, or does it arise from © Oxford University Press 1403 J.H.Steele and C.W.Clark inconsistencies in the underlying assumptions on which these two types of model are based? A plankton population model The basis for defining functions and choosing parameter values for population models should be the behaviour of individuals in the population—in acquiring food or avoiding predators. However, certain functions and parameter values are very poorly defined, or essentially unknown. This is apparent for the closure terms at the level of the 'predation mortality' on the Z. This effect becomes more obvious if the Z is decomposed into life cycle components:

Vertical migration of copepods

Diel vertical migration (DVM) by herbivorous copepods is a nearly universal feature of pelagic ecosystems. The ecosystem consequences of this behavior are less well understood. A simulation of copepod life cycles in the northern North Sea examines migration in terms of reproductive success at diapause. Different patterns of vertical migration appear to be less important than mixed strategies for onset of diapause to cope with interannual variability in the physical environment.

Effects of body size and harem size on male reproductive behaviour in the southern elephant seal

In a study on size and reproductive behaviour in the southern elephant seal, Mirounga leonina, on South Georgia from 1991 to 1993, large size, measured as nose to hind flipper length, was associated with factors that confer an advantage in terms of reproductive success. Some males stayed at the centre of harems, others were on the periphery and others were outside the harem. A male's mating success increased with his length, and for central males, mating success increased with harem size. Central males defeated almost all other males. Central males were also longest and outside males shortest. Furthermore, central males stayed ashore longest. For central males, length was positively correlated with number of days spent in the harem but not with harem size. Central and peripheral males had the highest copulation frequencies (per h and per male). The copulation frequency of central males apparently peaked in harems with a maximum size of 100–150 females, with lower frequencies in larger and smaller harems. However, the mating success of central males over the season increased with harem size. The rate of alert behaviour and time devoted to resting were not correlated with harem size for any of the three male categories, but rate of agonistic behaviour increased with increasing harem size for central males.

Effects of Repeated Applications of Bacillus thuringiensis israelensis on the Mosquito Predator Erythemis simplicicollis (Odonata: Libellulidae) from Hatching to Final Instar

Nymphs of a common dragonfly, Erythemis simplicicollis (Say), were exposed to Bacillus thuringiensis israelensis de Barjac at 1.2 ppm once a week for an entire life cycle in a controlled laboratory environment. Eight weekIy applications were administered to 2 treatment groups: external contact only, and external + internal contact using prey (mostly anopheline larvae) that had fed on B. thuringiensis . Each B. thuringiensis -treated group and a control group consisted of 15 nymphs. Mortality was not affected by B. thuringiensis applications. Repeated B. thuringiensis applications did not affect development to the adult stage, morphology, or maiden flight capability. Nymph size of the external contact group, measured by hind femur length and head width, was substantially smaller compared with the control group in most instars from 4–12. However, adult size, based on head width and hind wing length comparisons, did not differ among the 3 groups. Prey consumption and instar duration, which were highly correlated, did not account for the differences in size. Sex ratio (lower proportion of large females in the external group) and initial size (slightly smaller in instar 2 in the external group) appeared to be the major factors contributing to the size differences in the external group. However, these variables were not responsible for the external + internal contact group being smaller in instar 10 compared with the controls, as sex ratios and initial size were equal. If repeated B. thuringiensis applications affect size in E. simplicicollis , the effect may be insignificant in terms of reproductive success, as published studies do not show a positive relationship between size and reproductive success in dragonflies.

Intersexual Selection and Reproductive Success in the Pheasant Phasianus colchicus

Some recent sexual selection models predict that female choice in species without paternal care may function to discriminate among males in order to pass ''good genes'' to offspring. Data quantifying the relationship between female mate choice and reproductive success are scarce. In a Swedish population of pheasants females prefer to mate with long-spurred males. Male viability also correlates with male spur length. We used DNA fingerprinting to measure individual pheasants' reproductive success in terms of both hatchlings and surviving offspring. The data show that long-spurred males sired more hatchlings and surviving offspring and also that the females' production of surviving offspring correlated with their mate's spur length. The analyses also indicate that offspring of females who mated with long-spurred males experienced an increased survival rate. (Less)

COSTS OF REPRODUCTION INFLUENCE THE EVOLUTION OF SEXUAL SIZE DIMORPHISM IN SNAKES.

Most explanations for sex differences in adult body size have focused on differences between the two sexes in the degree to which larger body size enhances reproductive success. For example, the general tendency for females to grow larger than males has been attributed to production of larger litters by larger females (Darwin 1871; Trivers 1972; but see Shine 1988), and the correlation between large male size and mating systems with male-male competition has led many authors to conclude that larger male size enhances male reproductive success in such systems (Darwin 1871; Clutton-Brock et al. 1977; Shine 1978; Berry and Shine 1980). Because each of these hypotheses deals only with the relationship between body size and reproductive success within one sex, no prediction can be made about the relative sizes of the two sexes (Greenwood and Adams 1987; Shine 1987). The degree of size dimorphism is presumably determined by the relative intensities of selection for large size in the two sexes, as well as the degree of genetic correlation between the sexes for alleles associated with body size (Arnold 1985). It is entirely likely that large size enhances reproductive success in both sexes, but more strongly in one than in the other. In order to predict the actual direction or degree of sexual size dimorphism within a population, we need data on the effects of body size on reproductive success in both sexes. Such data are rarely available (Clutton-Brock 1988), so the balance between selective forces acting on conspecific males and females has rarely been evaluated. A comparative analysis of sexual size dimorphism and mating systems in snakes reveals that females grow larger than males in most species, but not in species that show male-male combat behavior (Shine 1978). The same pattern has been noted in many other animals, including other reptiles, and generally has been attributed to sexual selection for large male body size in taxa with male-male combat (Shine 1979; Berry and Shine 1980; Fitch 1981). Nonetheless, there are many exceptions to this generalization, and the most puzzling of these are species in which male-male combat occurs but in which females attain larger sizes than males. Species that fail to conform to the usual pattern may tell us a great deal about the factors responsible for those general patterns. In this paper, we use detailed demographic and ecological data on one of these atypical species (the adder Vipera berus) to test among potential explanations for female-larger dimorphism in a species with male-male combat. Our analyses suggest that sex differences in costs of reproduction may strongly influence optimal body sizes in each sex, and hence may affect the direction of sexual size dimorphism. We focus here on the potential costs and benefits of larger body size in terms of reproductive success, especially, fecundity selection in females and sexual selection in males.

Effects of Ectoparasites on Reproduction of Their Swallow Hosts: A Cost of Being Multi-Brooded

Many birds are negatively affected in terms of reproductive success by the presence of ectoparasites in their nests. We hypothesized that the negative effects of ectoparasitism on reproductive success would be a direct function of the number of clutches laid because of a seasonal increase in ectoparasite populations. Ectoparasites would negatively affect each clutch and the total effect of parasitism on annual reproductive success should therefore be relatively larger with an increasing number of clutches. This prediction was tested by fumigation of nests of swallows Hirundo rustica either following completion of the first clutch, completion of all clutches or by keeping nests as controls

Spatial relationships between mate acquisition probability and aggregation size in a gregarious coreid bug, (Colpula lativentris): A case of the ideal free distribution under perceptual constraints

SummarySpatial relationships of mate acquisition probability for individuals of both sexes of a gregariously‐mating coreid bug, Colpula lativentris, were studied in relation to aggregation size. Operational sex ratio was always strongly male biased. Mate acquisition probability of females was rather constant and independent of aggregation size, as predicted by an ideal free distribution. Moreover laboratory experiments showed that both multiple mating and rearing density little affected female fecundity, suggesting ideal free distribution of females in terms of reproductive success. On the other hand, mate acquisition probability of males was higher in larger aggregations, where more receptive females were available. This male discrepancy from an ideal free distribution was similar to the patterns predicted by an ideal free distribution under perceptual constraints (Abrahams, 1986), but not by that under unequal competitive ability.

Conservative Surgical Treatment for Severe Endometriosis in Infertile Women

Conservative surgery for severe endometriosis in infertile women is one of the most challenging situations for the pelvic surgeon. The second half of the 1980s saw an increase in the supporters of laparoscopic treatment even for more extensive disease. Two opposing factions were thus created: traditional gynecologic surgeons who accuse endoscopists of imprudence and technical inadequacy and enthusiastic supporters of operative laparoscopy who consider laparotomy obsolete and its associated morbidity needlessly high for the patient and health service. In the present review of the literature data we analyze laparotomy and laparoscopy techniques and compare the postoperative results in terms of reproductive success in an attempt to clarify whether conservative endoscopic treatment of severe endometriosis is only an inappropriate proposal with no future or whether, due to its efficacy, it will eventually limit interventions via laparotomy to exceptional circumstances.

Do phytoseiid mites select the best prey species in terms of reproductive success?

Optimal foraging theory predicts that predators prefer those prey species that are most rewarding in terms of reproductive success, which is dependent on prey quality and prey availability. To investigate which selection pressures may have moulded prey preference in an acarine system consisting of two prey species and three predator species, we tested whether prey preference of the predators is matched by the associated reproductive success. The predators involved areAmblyseius finlandicus (Oudemans),Am. potentillae (Garman) andTyphlodromus pyri Scheuten. The prey species are the apple rust mite (Aculus schlechtendali (Nalepa)) and the fruit-tree red spider mite (Panonychus ulmi (Koch)). Reproductive success was assessed in terms of intrinsic rate of increase and for one predator also in terms of diapause induction. All three predator species reached highest reproductive success on the same prey species: apple rust mite. This was most pronounced for the predatorAm. finlandicus, because its larval stage suffered severe mortality when feeding onP. ulmi. An independent study on prey preference of the three predator species (Dicke et al., 1988) revealed thatAm. finlandicus prefersAc. schlechtendali toP. ulmi, whereas the other two predator species have the reverse preference. Thus, on the basis of current data, prey preference ofAm. finlandicus can be understood in terms of reproductive success. However, this is not so for prey preference ofT. pyri andAm. potentillae. Investigations needed for a better understanding of prey preference of the last-named two predator species are discussed.

How to analyse prey preference when prey density varies? A new method to discriminate between effects of gut fullness and prey type composition

State-dependent changes in prey preference are among the phenomena to be expected in studies of predator behaviour. For example, the rate of attack on each prey type is well known to be affected by the state of satiation, the dynamics of which is often assumed to parallel that of gut fullness. An interesting question is whether satiation alone is the determinant of the attack rate or whether the particular mixture of prey types in the predator's direct environment has an additional influence by itself. To detect examples of the latter type the predictive method proposed by Cock (1978) may be useful. In the present paper the predictive tool is a model built on the assumption that gut fullness is the sole internal state variable determining the attack rate. It is provided with parameter estimates from observations in monocultures of each type and then used to predict predation in mixtures of prey types. When measured predation on these prey types differs from what is predicted, the model may be too simple in various respects, one of which is that predators change prey preference in response to their own sample estimates of the densities of each prey type and their (innate or sample) estimate of the profitability of each prey type in terms of reproductive success. Thus, the lack of fit of the model poses a challenging problem, for to explain it one must identify underlying causes, such as differences in prey quality with respect to scarce nutrients or noxious chemicals that need to be detoxified or rendered harmless in other ways. The predictive approach is illustrated by analysis of preference of predatory mites (Phytoseiulus persimilis Athias-Henriot and Typhlodromus occidentalis Nesbitt) with respect to various stages of development of their prey, the two-spotted spider mite (Tetranychus urticae Koch). The results show that the relation between attack rate and gut fullness might well explain prey stage preference of predatory mites when the prey stages are presented together rather than each alone. In another paper by Dicke et al. (1989) marked deviations between predicted and measured diet are reported when the predatory mite, Typhlodromus pyri Scheuten, was offered a choice between two prey species, i.e. apple rust mites and (larvae of) European red spider mites. The underlying causes are to be revealed by further research, the impetus of which is born out by use of the method proposed by Cock (1978) and extended in this paper.

Longevity factor in hominoid social organization

In most primate groups emigration of the maturing young of one or the other sex tends to serve as an incest avoidance mechanism. Among most primate species it is the males who change groups. This supports the theory that, in terms of reproductive success, males should compete for mates and females should compete for resources. In hominoids the combination of increased longevity and greater female discrimination in mate selection seems responsible for female emigration. This may relate to the high frequency of patrilocality and male control of resources among human groups.

Chorus dynamics of a neotropical amphibian assemblage: comparison of computer simulation and natural behaviour

The high population density of vocalizing males of the Puerto Rican treefrog Eleutherodactylus coqui in their natural habitat can lead to call overlap, which may interfere with the function of the call. Simulations of groups of calling males suggest that a given male can maximize the effectiveness of each call by actively avoiding acoustic overlap with at most two of its nearest neighbours. Analysis of vocal patterns of natural groups of frogs support this hypothesis: 14 of the 18 frogs tested actively avoided acoustic overlap with no more than two neighbours (one avoided acoustic overlap with three neighbours) while three frogs exhibited active call-jamming with one of their neighbours. Moreover, cross-correlograms of calling patterns between all pairs of frogs in a group were used to infer dynamic chorus structure. Overlap avoidance behaviour is discussed in terms of reproductive success and predator evasion.

Vitamin a deficiency modifies response of predatory miteAmblyseius potentillae to volatile kairomone of two-spotted spider mite,Tetranychus urticae

A volatile kairomone of the two-spotted spider mite,Tetranychus urticae, elicits a searching response of the phytoseiid predatorAmblyseius potentillae, only when the predator is reared on a carotenoid-free diet. However, after addition of crystalline β-carotene or vitamin A acetate to the predator's rearing diet this searching response was absent. Because vitamin A and β-carotene are indispensable nutrients for diapause induction, the carotenoid-deficient predators increase their fitness by searching for two-spotted spider mites, when other spider mites are unavailable. Two-spotted spider mites, among others, contain the carotenoids required for diapause induction, but are an inferior prey due to the dense webbing they produce. When the predators have carotenoids at their disposal, they do better by searching for other spider mites that are more profitable in terms of reproductive success. Such a prey is the European red spide mite,Panonychus ulmi. The volatile kairomone of this prey elicits a searching response of the predator whether it has a carotenoid deficiency or not.

Adaptive and incidental consequences of the alba polymorphism in an agricultural population of Colias butterflies: female size, fecundity, and differential dispersion.

A sex-limited color dimorphism occurs in many populations of Colias eurytheme. Alba females exhibit different patterns of resource allocation and are less attractive than orange females. This study examines some of the consequences of these differences in terms of reproductive success and population structure in a high density agricultural population.Alba females produced more eggs than orange females on a daily basis, but the morphs did not differ in three measures of size. Spermatophore counts revealed that fresh and worn females did not differ in mating frequency between the two morphs, but very worn alba females gained more matings than very worn orange females.In two mark-release-recapture experiments, alba females exhibited longer residence times than orange females. Changes in population structure over time suggest that this was due to dispersal of orange females from the mature field. Evidence is presented that orange females emigrate in response to male harassment at high density while alba females, exposed to less harassment, remain behind. We suggest that the persistence of the polymorphism in this agricultural population is at least partially facilitated by the cyclic cutting of the alfalfa.

On climatic analogs in paleoclimatic reconstruction

Many of the problems that have been discussed with regard to the analog approach to paleoclimatic reconstruction may be illustrated by consideration of basic principles and definitions, and the logical consquences thereof. Specific attention is directed toward the definition of the regional macroclimate as the modal microclimate and to a series of axioms: (1) There are various microclimates which depart more or less from the macroclimate in each terrestrial region. (2) Environment and climate change on time scales from near instantaneous to millions of years. (3) Climate is multidimensional (a vector), not a single scalar datum. (4) Biotic assemblage changes in response to environmental (including climatic) changes are expressed primarily in terms of reproductive success. One may conclude from the corollaries to these axioms that perfect analogs cannot be found for any Holocene climate, but that “partial analogs” (“transfer equations”) may still be used if allowance is made for shared variance.

THE EXPERIMENTAL ASSESSMENT OF FITNESS IN DROSOPHILA. I. COMPARATIVE MEASURES OF COMPETITIVE REPRODUCTIVE SUCCESS

Strains of D. melanogaster, representing a range of genetic diversity, were systematically subjected to each of several techniques that have been devised to assess total or net fitness. All of these techniques operationally define fitness in terms of reproductive success under competitive conditions. For the set of strains tested, an excellent correlation was obtained between the competitive indices produced by two single-generation intraspecific competitions, despite fundamental differences in the strains used as competitive standards. The results of two interspecific tests were also correlated, but the intraspecific vs. interspecific test result comparisons ranged from highly significant to nonsignificant correlations. For the fitness estimates, the overall variances produced by the intraspecific tests were greater than those obtained in the interspecific competitions. No significant correlations were found between the results of a long-term (multi-generation) competitive assessment of fitness and any of the single-generation tests. Therefore, although all of these tests refer to a net parameter called "fitness", they are clearly not all measuring the same thing. Differences in the competitive interactions operative in each technique are suggested to account for these results.

Social rank and darwinian fitness in a multimale group of Barbary macaques (Macaca sylvana Linnaeus, 1758). Dominance reversals and male reproductive success.

In a 5-year study data were compared on rank and reproductive success of 3 mature males in a group of barbary macaques who had sired 32 infants on 14 females. The results indicate that the absolute number of offspring as well as the proportion of offspring from higher-ranking females is a function of the male's rank. Asymmetrical access to receptive females was produced by either a high basic rank or by the formation of a coalition, or both of these, which resulted in at least partial exclusion of competitors from reproduction. Rank reversals in basic rank was preceded by severe fights between the opponents involving deep wounds or loss of canine teeth. When such fights occurred they reaped benefits in each case for the challenger, which were measurable in terms of reproductive success.