Genetic monogamy in Monteiro's hornbill, Tockus monteiri

Hornbills display a unique breeding habit in which the female seals herself into the nest cavity prior to egg laying and remains ensconced for most of the breeding cycle. This habit necessitates long-term sperm storage, which considerably lengthens the fertile period of the female. This in turn increases the amount of time available to females to engage in extrapair copulations. Because food delivered by the male is the primary source of energy for female maintenance, egg production, incubation, female moult and offspring provisioning, male parental investment (and thus cuckoldry) in these hornbills is extremely expensive. This combination of costly male parental care and female dependence potentially places hornbills at a critical endpoint in the spectrum of genetic promiscuity operating within pairs of socially monogamous birds. A paradigm of reproductive conflict suggests that these factors might allow males to coerce females into a state of genetic monogamy. Sperm storage, however, might allow female hornbills to thwart monopolization attempts by their mates. We used minisatellite multilocus DNA fingerprinting to analyse paternity in a Namibian population of Monteiro's hornbill, Tockus monteiri. Despite the ability of female hornbills to store sperm for long periods, we found no evidence of extrapair paternity (EPP). Although we cannot explicitly rule out a role for coercion in the evolution of the genetic monogamy we observed, the benefits of EPP appear to be devalued to the point that the reproductive interests of males and females overlap considerably. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Chemical characterization of milk oligosaccharides of the polar bear, Ursus maritimus

Two trisaccharides, three tetrasaccharides, two pentasaccharides, one hexasaccharide, one heptasaccharide, one octasaccharide and one decasaccharide were isolated from polar bear milk samples by chloroform/methanol extraction, gel filtration, ion exchange chromatography and preparative thin-layer chromatography. The oligosaccharides were characterized by ¹H-NMR as follows: the saccharides from one animal: Gal(α1-3)Gal(β1-4)Glc (α3′-galactosyllactose), Fuc(α1-2)Gal(β1-4)Glc (2′-fucosyllactose), Gal(α1-3)[Fuc(α1-2)]Gal(β1-4)Glc (B-tetrasaccharide), GalNAc(α1-3)[Fuc(α1-2)]Gal(β1-4)Glc (A-tetrasaccharide), Gal(α1-3)Gal(β1-4)GlcNAc(β1-3)Gal(β1-4)Glc, Gal(α1-3)[Fuc(α1-2)]Gal(β1-4)GlcNAc(β1-3)Gal(β1-4)Glc, Gal(α1-3)Gal(β1-4)GlcNAc(β1-3)[Gal(α1-3)Gal(β1-4)GlcNAc(β1-6)]Gal(β1-4)Glc; the saccharides from another animal: α3′-galactosyllactose, Gal(α1-3)Gal(β1-4)[Fuc(α1-3)]Glc, A-tetrasaccharide, GalNAc(α1-3)[Fuc(α1-2)]Gal(β1-4)[Fuc(α1-3)]Glc (A-pentasaccharide), Gal(α1-3)Gal(β1-4)[Fuc(α1-3)]GlcNAc(β1-3)Gal(β1-4)Glc, Gal(α1-3)Gal(β1-4)[Fuc(α1-3)]GlcNAc(β1-3)Gal(β1-4)[Fuc(α1-3)]Glc (difucosylheptasaccharide) and Gal(α1-3)Gal(β1-4)[Fuc(α1-3)]GlcNAc(β1-3){Gal(α1-3)Gal(β1-4)[Fuc(α1-3)]GlcNAc(β1-6)}Gal(β1-4)Glc (difucosyldecasaccharide). Lactose was present only in small amounts. Some of the milk oligosaccharides of the polar bear had α-Gal epitopes similar to some oligosaccharides in milk from the Ezo brown bear and the Japanese black bear. Some milk oligosaccharides had human blood group A antigens as well as B antigens; these were different from the oligosaccharides in Ezo brown and Japanese black bears.     

6-Demethylvignafuran as a phytoalexin of Tetragonolobus maritimus

A phytoalexin isolated from the fungus-inoculated leaves of Tetragonolobus maritimus has been identified as 6-demethylvignafuran (2-[4-hydroxy-2-methoxyphenyl]-6-hydroxybenzofuran). The synthesis of 6-demethyl-vignafuran and two isomeric benzofurans is described. The presence of 3,9-dihydroxypterocarp-6a-ene in T. maritimus is also reported.     

Experimental analysis of monogamy in the Caribbean cleaner goby, Gobiosoma evelynae

To investigate factors promoting monogamy, we studied the reproductive behaviour and ecology of the monogamous Caribbean cleaner goby at two sites near St Croix, U.S. Virgin Islands. We assessed mate fidelity and the amount of time required to acquire a new mate in experimentally widowed males and females. We also measured behavioural responses of pair members and single females to experimentally introduced conspecific intruders of both sexes. Finally, we evaluated the distribution of suitable habitat relative to existing goby territories. We found that pairs often separated due to males abandoning females and moving to a new territory, that most widowed fish soon acquired a new mate, and that there was strong aggression towards large same-sex intruders. We also found an abundance of suitable, unoccupied habitat. We conclude that pairs are maintained by intrasexual aggression that is related to both mate availability and other resources, such as high-quality, food-rich cleaning stations. Combined with observations of frequent pair separation, interterritory male movement, and relatively rapid remating by both sexes, these results suggest a complex mating system that is best classified as serial monogamy. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.      

Signals of status in wintering white-crowned sparrows, Zonotrichia leucophrys gambelii

The possibility of plumage status signalling within the social systems of wintering birds has been a controversial issue. Our results are the first to demonstrate conclusively the reality of such signalling. Data from eight groups of captive white-crowned sparrows (Zonotrichia leucophrys gambelii), each with 8 to 11 different individuals, show that immature and adult females with crowns painted to resemble more brightly coloured, dominant adult males consistently win encounters with control birds of their own age and sex. These experiments demonstrate that signals that correlate with age (adult versus immature) and sex (adult male versus adult female) are used by the birds as reliable indicators of relative dominance position. Our demonstration of status signalling draws attention to the need to explain how such a system can be evolutionarily stable and we discuss some suitable models.     

Female polar bears, Ursus maritimus, on the Barents Sea drift ice: walking the treadmill

For animals in dynamic habitats, the contribution of passive (i.e. by wind or current) and active (movements by the animals themselves) displacement determines whether their space use reflects physical or adaptive behavioural processes. Polar bears in the Barents Sea undertake extensive annual migrations in a habitat that is highly dynamic because of continuous sea ice drift. Using combined information from satellite telemetry, satellite images and atmospheric pressure recordings, we estimated the contribution of sea ice drift and movements in the monthly net displacement of female polar bears. We found that movements, and thus behavioural processes, were dominant. Net displacement was directed northwards during summer ice retreat and southwards during winter ice advance. Conversely, movements were directed northwards counteracting a continuous southward drift. Acting as a treadmill, ice drift probably increased the energetic cost of migrations relative to that expected from observed net displacement distances; this suggests that pelagic and adjacent near-shore bears, on stable land-fast ice, have different energy costs. Little concordance between ice drift rates and net displacement and movement rates suggest that polar bears do not adjust their displacement relative to attractive areas with fixed locations, but rather adjust their movements to local habitat suitability. Furthermore, selective use of less dynamic drift ice when with cubs-of-the-year, and use of terrestrial denning areas, appear to be behavioural adaptations to the dynamics of the Barents Sea drift ice. Hence, understanding the behaviour and ecology of animals inhabiting dynamic habitats necessitates incorporation of both dynamic and static habitat variables. Copyright 2003 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour.      

Number of males in primate groups: Comparative tests of competing hypotheses

Primate social groups frequently contain multiple males. Male group size has been hypothesized to result from male mating competition, but the selective factors responsible for the evolution of multimale groups are unclear. Short breeding seasons create situations that are not conducive for single males to monopolize mating access to females, and may therefore favor the formation of large male groups. Alternatively, since the costs of mate defense increase with the spatial clumping of females, female group size may be a primary determinant of the number of males in a primate group. We used comparative methods designed to control for the potentially confounding effects of hidden third variables associated with phylogeny to test the breeding season and female group size hypotheses for the evolution of multimale groups. Our results revealed no association between breeding season duration and the number of males in groups. In contrast, we provide support for the female group size hypothesis by demonstrating a strong pattern of correlated evolution between female and male group size. © 1996 Wiley-Liss, Inc.