The natural history of a monogamous coral-reef fish, Valenciennea strigata (Gobiidae): 2. behavior, mate fidelity and reproductive success

This study examined the behavior and reproduction of a monogamous coral-reef fish, Valenciennea strigata, to determine mate fidelity and the proximate causes of monogamy. Most fish were found in monogamous pairs that remained together over several rounds of reproduction. Pairs stayed within close proximity to each other and their burrows. Females fed at a higher rate than their mates, while males spent more time maintaining burrows. Females spawned every 13 days; males guarded eggs in the burrow for 2–3 days. Although females limited the RS of males, males did not mate polygynously under natural conditions. Reproductive success (RS) was affected primarily by survival, and secondarily by size. Both sexes enforced monogamy by guarding their mates. Three factors facilitated mate guarding: (1) all males were able to hold a nest site, (2) both sexes showed strong site fidelity, and (3) residents had an advantage in contests over mates. Thus, mates were economically defensible. Additionally, females formed a crescent of dark pigments on their abdomen that resembled a gravid condition; these marks may enhance continuation of the pair bond. Both sexes preferred large mates, and pairs were positively assorted by size. Males benefited from guarding large females because fecundity increased with size. Females may benefit from the burrowing of males, and larger males should be better burrowers.     

Carry-over effects of the social environment on future divorce probability in a wild bird population

Initial mate choice and re-mating strategies (infidelity and divorce) influence individual fitness. Both of these should be influenced by the social environment, which determines the number and availability of potential partners. While most studies looking at this relationship take a population-level approach, individual-level responses to variation in the social environment remain largely unstudied. Here, we explore carry-over effects on future mating decisions of the social environment in which the initial mating decision occurred. Using detailed data on the winter social networks of great tits, we tested whether the probability of subsequent divorce, a year later, could be predicted by measures of the social environment at the time of pairing. We found that males that had a lower proportion of female associates, and whose partner ranked lower among these, as well as inexperienced breeders, were more likely to divorce after breeding. We found no evidence that a female''s social environment influenced the probability of divorce. Our findings highlight the importance of the social environment that individuals experience during initial pair formation on later pairing outcomes, and demonstrate that such effects can be delayed. Exploring these extended effects of the social environment can yield valuable insights into processes and selective pressures acting upon the mating strategies that individuals adopt.     

Correlates of genetic monogamy in socially monogamous mammals: insights from Azara's owl monkeys

Understanding the evolution of mating systems, a central topic in evolutionary biology for more than 50 years, requires examining the genetic consequences of mating and the relationships between social systems and mating systems. Among pair-living mammals, where genetic monogamy is extremely rare, the extent of extra-group paternity rates has been associated with male participation in infant care, strength of the pair bond and length of the breeding season. This study evaluated the relationship between two of those factors and the genetic mating system of socially monogamous mammals, testing predictions that male care and strength of pair bond would be negatively correlated with rates of extra-pair paternity (EPP). Autosomal microsatellite analyses provide evidence for genetic monogamy in a pair-living primate with bi-parental care, the Azara''s owl monkey (Aotus azarae). A phylogenetically corrected generalized least square analysis was used to relate male care and strength of the pair bond to their genetic mating system (i.e. proportions of EPP) in 15 socially monogamous mammalian species. The intensity of male care was correlated with EPP rates in mammals, while strength of pair bond failed to reach statistical significance. Our analyses show that, once social monogamy has evolved, paternal care, and potentially also close bonds, may facilitate the evolution of genetic monogamy.     

Duetting—A mechanism to strengthen pair bonds in a dispersed pair‐living primate (Lepilemur edwardsi)?

Duetting is defined as an interactively organized pair display in which one pair partner coordinates its vocalizations in time with those of the other. It is widespread among tropical birds and cohesive pair‐living primates, in which it is suggested to strengthen pair bonds. We know very little about the presence and function of duetting in dispersed pair‐living mammals. We studied duetting behavior in a solitary foraging, but pair‐sleeping, primate, the Milne Edwards' sportive lemur, in a dry deciduous forest of north‐western Madagascar. We radio‐tracked six pairs throughout 1 year and recorded their sleeping sites and associations, home‐range use, and vocal and behavioral interactions. Three different periods were covered (mating, pregnancy, and offspring care). Sleeping partners form long‐term pair bonds, indicated by an almost exclusive pair‐specific usage of sleeping sites and home‐ranges across periods. We explored three functional hypothesis of duetting: mate reunion, pair reunion, and joint‐territorial defense. Pairs regularly engaged in duet calling. Duetting increased significantly during the offspring care period. Duetting occurred significantly more often at feeding sites than at sleeping sites. Pair partners synchronized behavioral activities after duetting. The activity most often synchronized was locomotion. Pair partners played an equal role in duetting with no difference between sexes in starting or terminating duetting. Altogether, our results provide support for the hypothesis that in dispersed pair‐living primates, duetting evolved as a mechanism to coordinate activities between pair partners dispersed in space, to strengthen pair bonds, and, perhaps, to limit infanticide and nutritional stress in lactating females. Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc.     

Das Kopulationsverhalten von Kiebitzen (Vanellus vanellus) im Verlauf der Brutsaison

Zusammenfassung Von 1996 bis 2000 wurden insgesamt 43 verschiedene und 58 des Kiebitz jeweils vom 1. März bis 15. Juni beobachtet. Während 79 Ganztagsbeobachtungen mit insgesamt 1109 Stunden wurden 767 Kopulationen registriert. Eine Kopulation dauerte in allen Phasen des Brutgeschäftes durchschnittlich 1,7 s. Die ersten Begattungen wurden acht bis zehn Tage nach Erstbeobachtung der im Revier der und je vier bis sechs Tage vor Legebeginn ab Anfang/Mitte März festgestellt. Die letzten Begattungen waren noch Anfang Juni zu beobachten. Die Kopulationen verteilten sich über den ganzen Tag mit Maxima in den frühen Morgen- und späten Nachmittag- bzw. frühen Abendstunden. Bis zum vollständigen Gelege wurde jedes 40- bis 70-mal begattet. Diese häufigen Kopulationen könnten zur Festigung und zum Erhalt von Paarbindungen beitragen. Auch während der gesamten Gelegebebrütung kopulierten die Brutpartner durchschnittlich zwei- bis dreimal täglich. Hier erfolgten 51,5 % aller Kopulationen bei der Ablösung des brütenden durch das . Mit zunehmender Zahl an Brutablösungen nahm die Anzahl der Ablösungen mit Kopulation zu. Insgesamt wurde im Durchschnitt bei jeder vierten Brutablösung kopuliert. Nur an 18 (13,5 %) von insgesamt 133 beobachteten Bebrütungstagen eines konnte den ganzen Tag über keine Begattung festgestellt werden. Polygyne hielten zu all ihren sexuellen Kontakt. Mit dem Schlupf der Küken wurden die Kopulationen eingestellt. Erneut einsetzende Begattungen während des Jungeführens oder nach Kükenverlust erfolgten im Rahmen der Ablage eines Zweitgeleges. Zwischen Gelegealter und Kopulationshäufigkeit wurde kein Zusammenhang gefunden. Fremdkopulationen (EPCs) wurden nicht beobachtet. Kopulationen während der Gelegebebrütung dienen daher wohl nicht zur Verhinderung von Fremdbefruchtung eines Ersatz- oder Zweitgeleges. Sie sind wohl während der Bebrütung ebenso nicht nötig, um das Follikelwachstum und die Keimdrüsen für ein weiteres Gelege zu stimulieren, da auch nach mehreren Wochen ohne Kopulation innerhalb weniger Tage der Follikelsprung ausgelöst wurde. Offenbar sind Kopulationen während der Bebrütungsphase unabhängig von ihrer eigentlichen Befruchtungsfunktion. Die sehr häufigen Kopulationen scheinen Kommunikationsfunktion im Sinne der Aufforderung zur Brutablösung zu haben und können die Paarbindung stärken und so eine optimale Bebrütung des Geleges ermöglichen.

---

The copulation behaviour of Lapwings (Vanellus vanellus) throughout the breeding season

Summary From 1996 to 2000 43 male and 58 female Lapwings were observed from March 1st until June 15th. During 79 full day observations over a total of 1109 hours, 767 copulations were recorded. Viewed over the whole breeding period a copulation took on average 1.7 seconds. The first matings (beginning of March) were registered eight to ten days after the arrival of the female in the male territory; four to six days later egg laying started. The last copulations were still being observed in early June. Matings were observed at all times of the day with peaks in the early morning and late afternoon. By the time the clutch was completed each female lapwing had taken part in 40 to 70 copulations. Frequent copulation may promote pair bonding. Over the complete incubation period the partners copulated on average two to three times a day. 51.5 % of copulations occured during brood relief of the male by the female. With an increasing number of brood reliefs the number of male to female reliefs with copulations became more frequent. All in all matings took place on average every fourth brood relief. Over 133 days of observation of an incubating fermale on only 18 days (13.5 %) were no copulations at all recorded. Polygamous males kept up contact to all their mates. The copulations finished on the hatching of the chicks. During chick leading or after the loss of chicks, matings started again for a second clutch. No connection was found between the age of a clutch and the frequency of copulations. Extra-pair copulations (EPCs) were not observed. Therefore matings during the incubation period would not appear to serve to prevent the extra-pair fertilization of a replacement or second clutch. Copulations during incubation time seem to be unnecessary to stimulate follicle growth and the germ glandular for a second clutch, because even after several weeks of abstention, an ovulation could be provoked within a few days. Copulations during the breeding period are obviously not connected to their regular function of fertilization. The very large number of copulations may have a communicative function stimulating turn-taking at brooding and helping to stabilize the pair bond, with a positive effect on the breeding success.

     

Sneaking by harem masters of the sandperch, Parapercis snyderi

Reproductive behavior of the sandperch Parapercis snyderi was studied in the coastal waters of Shikoku Island, Japan. This fish is a monandric and protogynous hermaphrodite. Males maintained home ranges of ca. 10 m² that slightly overlapped with each other. Harems included on average 2.45 females that were spaced out from each other. Males mated successively in pairs with the harem members within two hours before sunset. To release gametes, the pair rushed upward 10–200 cm. The pair spawning was sometimes parasitized by sneaking of an adjacent harem master, which had usually finished mating with his own mates. More than 80% of the sneaking rushes reached the apex of the pair rise, suggesting a high success rate of sneaking. Such sneaking by harem masters has not been reported in the genus Parapercis. The comparative reproductive ecology of this genus suggested that sneaking in P. snyderi is due to the close proximity of adjacent harems.