Evidence Of Extrapair Fertilizations Research Articles

Mate Opportunity Hypothesis and Extrapair Paternity in Waved Albatrosses (Phoebastria Irrorata)

Abstract Early arrival at breeding sites can influence reproductive success through enhanced access to critical resources such as nest sites or mates. One hypothesis explaining protandry, or male-first arrival at breeding sites, proposes that males arrive earlier to increase their extrapair copulation (EPC) opportunities, which may, in turn, enhance males' reproductive success through extrapair fertilizations (EPFs) (“mate opportunity hypothesis”). Extrapair behavior is unexpected in long-lived birds, in which the male is expected to abandon a brood of uncertain paternity, because his probability of future reproduction is high. A previous study of the Waved Albatross (Phoebastria irrorata), a long-lived, socially monogamous seabird, showed evidence of EPFs in 4 of 16 (25%) families. Here, we combined behavioral observations of copulations with additional molecular genetic evidence of EPFs in Waved Albatross families to investigate the fitness consequences of protandry under the mate opportunity hypothesis. During three breeding seasons, we documented 3,661 attempted copulations between birds of known identity; >60% of copulations that involved at least one breeding bird were classified as EPCs. Protandry was pronounced in all three study years: 76.3–96.6% of males arrived before (typically, 6–10 days before) their social mates. Early arrival was associated with increased opportunities for copulations: individual EPC frequencies were higher for breeding males than for breeding females, and males that arrived earlier than their social mates engaged in the most EPCs. Extrapair fertilizations were also regular in our study population; social fathers were excluded as the genetic sire in 14–21% of families. Egg laying dates of EPFs tended to be earlier in the season than those of within-pair fertilizations (WPFs). However, earlier arrival by a male did not translate into a higher probability of siring either within-pair or extrapair offspring, nor did cuckolding males have enhanced reproductive success. Although the fitness consequences of early arrival remain unclear, these findings suggest alternative advantages of early arrival for male Waved Albatrosses. La Hipótesis de Oportunidad de Apareamiento y Paternidad Extra-pareja en Phoebastria irrorata

MATE OPPORTUNITY HYPOTHESIS AND EXTRAPAIR PATERNITY IN WAVED ALBATROSSES (PHOEBASTRIA IRRORATA)

Abstract Early arrival at breeding sites can influence reproductive success through enhanced access to critical resources such as nest sites or mates. One hypothesis explaining protandry, or male-first arrival at breeding sites, proposes that males arrive earlier to increase their extrapair copulation (EPC) opportunities, which may, in turn, enhance males' reproductive success through extrapair fertilizations (EPFs) (“mate opportunity hypothesis”). Extrapair behavior is unexpected in long-lived birds, in which the male is expected to abandon a brood of uncertain paternity, because his probability of future reproduction is high. A previous study of the Waved Albatross (Phoebastria irrorata), a long-lived, socially monogamous seabird, showed evidence of EPFs in 4 of 16 (25%) families. Here, we combined behavioral observations of copulations with additional molecular genetic evidence of EPFs in Waved Albatross families to investigate the fitness consequences of protandry under the mate opportunity hypothesis...

Social and Genetic Monogamy in Territorial and Loosely Colonial Populations of Phainopepla (Phainopepla Nitens)

Abstract We observed courtship and copulatory behavior in two populations of Phainopeplas (Phainopepla nitens) with contrasting social systems and used multilocus DNA fingerprinting to assess rates of extrapair fertilization (EPF). Phainopeplas from both territorial and loosely colonial populations copulated infrequently (≤2 times per day). No extrapair copulations (EPCs) were observed in either population. We found no evidence of EPFs in 48 nestlings from 25 nests. Thus, Phainopeplas appear to be both socially and genetically monogamous. However, Phainopeplas are not monogamous over their lifetimes—they do not retain mates from year to year and appear to switch mates between breeding localities within the same year. Compressed breeding seasons, geographically shifting food resources, and widespread breeding failures may favor monogamy during any given breeding attempt while allowing opportunities to switch mates between breeding localities and years.

Genetic Relationships of Cory's Shearwater: Parentage, Mating Assortment, and Geographic Differentiation Revealed by DNA Fingerprinting

AbstractWe used DNA fingerprinting to assess genetic structure of populations in Cory's Shearwater (Calonectris diomedea). We analyzed mates and parent-offspring relationships, as well as the amount and distribution of genetic variation within and among populations, from the level of subcolony to subspecies. We found no evidence of extrapair fertilization, confirming that the genetic breeding system matches the social system that has been observed in the species. Mates were closely related, and the level of genetic relatedness within populations was within the range usually found in inbred populations. In contrast to previous studies based on allozymes and mtDNA polymorphism, DNA fingerprinting using microsatellites revealed consistent levels of genetic differentiation among populations. However, analyzing the two subspecies separately revealed that the pattern of genetic variation among populations did not support the model of isolation by distance. Natal dispersal, as well as historic and/or demographic events, probably contributed to shape the genetic structure of populations in the species.

GENETIC RELATIONSHIPS OF CORY'S SHEARWATER: PARENTAGE, MATING ASSORTMENT, AND GEOGRAPHIC DIFFERENTIATION REVEALED BY DNA FINGERPRINTING

Abstract We used DNA fingerprinting to assess genetic structure of populations in Cory's Shearwater (Calonectris diomedea). We analyzed mates and parent-offspring relationships, as well as the amount and distribution of genetic variation within and among populations, from the level of subcolony to subspecies. We found no evidence of extrapair fertilization, confirming that the genetic breeding system matches the social system that has been observed in the species. Mates were closely related, and the level of genetic relatedness within populations was within the range usually found in inbred populations. In contrast to previous studies based on allozymes and mtDNA polymorphism, DNA fingerprinting using microsatellites revealed consistent levels of genetic differentiation among populations. However, analyzing the two subspecies separately revealed that the pattern of genetic variation among populations did not support the model of isolation by distance. Natal dispersal, as well as historic and/or demographi...

The Mating Strategies of Eastern Screech-Owls: A Genetic Analysis

We used genetic analysis to examine the mating strategies of male and female Eastern Screech-Owls (Otus asio) in central Kentucky. DNA fingerprinting revealed no evidence of extra-pair fertilizations in 23 broods (80 nestlings). Such results suggest that pursuit of extra-pair copulations by male and female screech-owls may be costly. One possible cost for females is the risk of losing the nest site. Alternatively, pursuit of extra-pair matings by females might be energetically expensive, thereby conflicting with egg production. Male screech-owls provide food for their mate (and young) during much of the breeding season and such feeding probably affects reproductive success. Males pursuing EPCs might have less time for foraging and, as a result, reduced reproductive success.

Helpers liberate female fairy-wrens from constraints on extra-pair mate choice

In cooperatively breeding superb fairy-wrens (Malurus cyaneus), all males contribute to the feeding and defence of young. Despite the expectation that such paternal care should be directed only to relatives, DNA fingerprinting revealed that most offspring (76%, 138 out of 181) were sired by extra-group males that contributed no care, and that almost all broods (95%, 38 out of 40) contained young sired by extra-group fathers. This is the highest known incidence of cuckoldry. This remarkable mating system is produced by female control of fertilization and consistent preference for certain extra-group male genotypes. This choice leads to the production of sons that also gain extra-group fertilizations. One constraint on the extra-pair mate choice of females is the level of parental assistance received from males. Males living in pairs contribute relatively more parental care and are more likely to gain paternity in one of their broods (85%, 11 out of 13) than dominant males in multi-male cooperative groups (30%, 8 out of 27). In groups helpers compensate for the lower parental assistance of dominant males, so the total feeding rate is similar between pairs and groups. This suggests that females allow males in pairs more paternity to ensure their assistance with parental care. Helpers provide an alternative source of paternal investment, and allow females to express unrestricted mate choice. Mating options for females in other species with female control of fertilization may also reflect a trade-off between acquiring the genes of high-quality males for their offspring and parental care of those offspring.

Extrapair Fertilization in Monogamous Bull-Headed Shrikes Revealed by DNA Fingerprinting

-We analyzed parentage in a wild population of the Bull-headed Shrike (Lanius bucephalus) by DNA fingerprinting. Male Bull-headed Shrikes pair with a single female and defend a large all-purpose territory. Generally, both parents provide substantial parental care. Among 99 nestlings from 24 clutches, 10 (10%) nestlings from 4 (17%) clutches had extrapair paternity, but were offspring of the females. These results show that copulation frequency is not necessarily a good measure of reproductive success even in monogamous birds where no extrapair copulations are observed. The average band-sharing proportion between full siblings was the same as that between parent and offspring, but the variance was greater. This is likely the case because the band-sharing proportion reflects the gene-sharing proportion. Received 6 May 1991, accepted 9 February 1992. OvER 90% of birds are thought to be monogamous (Lack 1968), and males of these species employ mate guarding to avoid being cuckolded (M0ller 1985). Nevertheless, recent evidence from field observations and genetic analyses has clearly demonstrated that extrapair copulations (EPCs) and extrapair fertilizations (EPFs) occur in monogamous species. Among colonially breeding species of monogamous birds like Bank Swallows (Riparia riparia; Beecher and Beecher 1979) and Cattle Egrets (Bubulcus ibis; Fujioka and Yamagishi 1981), EPCs occur frequently. In Purple Martins (Progne subis; Morton et al. 1990) and Zebra Finches (Taeniopygia guttata; Birkhead et al. 1990), EPCs often result in fertilization, and intraspecific brood parasitism (ISBP) has been documented. In House Sparrows (Passer domesticus), which have a loosely colonial breeding system, up to 8% of the offspring were not fathered by their putative male parent (Wetton et al. 1987). EPCs have been recorded even in species with large all-purpose territories, where individuals are relatively difficult to observe. In Indigo Buntings (Passerina cyanea), EPCs often resulted in EPFs (Westneat 1987a, b), while in monogamous Willow Warblers (Phylloscopus trochilus), EPCs resulted in few EPFs (Gyllensten et al. 1990). These results show that copulation frequency is not necessarily a good measure of reproductive success. However, there are only a few genetic studies of strongly monogamous and territorial species; all have found low frequencies of EPFs. The Bull-headed Shrike (Lanius bucephalus) has a strongly monogamous breeding system and has a large all-purpose territory (radius ca. 100 m; Yamagishi 1982b). No EPCs have been observed (Yamagishi and Saito 1985). In monogamous birds for which no EPCs have been observed, there are few studies involving the determination of parentage; an exception is an analysis of Dunnocks (Prunella modularis) under a monogamous system (Burke et al. 1989). Their study showed that in monogamous pairs no EPFs occurred, so that the reproductive success of a pair was related to the number of fledged young. To test if this was also the case for Bull-headed Shrikes, we looked for evidence of EPFs and ISBP using DNA fingerprinting, which can be a powerful tool for determining parentage (Jeffreys et al. 1985b). STUDY AREA AND METHODS Study area and capture techniques.-The study was conducted from March to June 1989 in Oizumi city park, Osaka Prefecture, central Japan (34?34'N, 135?32'E). The park covers an area of about 70 ha, is about 20 m in elevation, and is planted mainly with oaks (Quercus). The incubating female and/or the female and the male that fed their nestlings were captured with a mist net, and were regarded as the putative father and mother of the brood. All males that produced extrapair offspring were captured during incubation or nestling period (i.e. when their female mate was not fertilizable, therefore, a capture of the male did not affect our results). Age determination was based on the coloration of the wing coverts (Yamagishi 1982a). DNA fingerprinting.-DNA was prepared from 100 ,ul blood samples collected by jugular venipuncture