Heterosexual Pairs Research Articles

THE POPULATION STRUCTURE OF THE SYMBIOTIC CRAB, <i>TRAPEZIA</i> <i>SEPTATA</i> (DECAPODA, TRAPEZIIDAE) AT THE EARLY STAGES OF CORAL COLONY DEVELOPMENT

Symbiotic invertebrates play crucial roles in coral reef ecosystems due to their extremely high abundance and biomass, and by maintaining coral fitness and protecting them from predation. Among these invertebrates, symbiotic crabs of the family Trapeziidae are especially important for branching corals of the family Pocilloporidae. In this research, we studied the spatial arrangement and parameters of the populations of the symbiotic crab, Trapezia septata at the early stage of Pocillopora verrucosa colony formation. The study was conducted based on symbionts sampled from small coral colonies exposed for three months at a coral nursery in the Nha Trang Bay, Vietnam. As much as 59.5% of the study colonies are shown to be inhabited by the T. septata crab. The percentage of inhabited colonies grows proportionately to their volume. The male to female ratio is 1.4, being skewed to males. The number of males and females is increased with the volume of inhabited colonies, as is the average size of individuals. Individual colonies are commonly inhabited by a single crab or heterosexual pairs. Sexual dimorphism was found, females being larger than males. A positive relationship between the sizes of males and females in pairs was revealed, as in 73% pairs females were larger than males. The size of the clutch correlated positively to the size of the female. We hypothesize that the predominance of males in the population, as well as the individuals located among the hosts one by one, is the result of intersexual competition

Charity Bryant and the Queer Affordances of the Early American Acrostic

Abstract: This article investigates early American women's acrostic poetry, especially as it was written and exchanged in same-sex friendships and romantic relationships. It begins with a discussion of male poets' deployment of the print acrostic in the service of courtship, considering how such poems expose women to the public eye. Women's manuscript acrostics, on the other hand, refuse the isolation of the female subject in the heterosexual pair, instead creating community in their composition and circulation practices. By way of example, the article turns to acrostic poetry written and received by Charity Bryant, a young teacher from New England whose affections for other women prompted the exchange of manuscript acrostics that fit same-sex love into the larger framework of gendered respectability and morality. Taken together, these poems demonstrate the adaptation of women's manuscript practices to relationships that included but went well beyond the rhetoric of romantic friendship. In this exchange, the article argues, acrostics normalize same-sex relationships, making them legible and preserving them for posterity.

Ancestral sex-role plasticity facilitates the evolution of same-sex sexual behavior

Recent attempts to explain the evolutionary prevalence of same-sex sexual behavior (SSB) have focused on the role of indiscriminate mating. However, in many cases, SSB may be more complex than simple mistaken identity, instead involving mutual interactions and successful pairing between partners who can detect each other's sex. Behavioral plasticity is essential for the expression of SSB in such circumstances. To test behavioral plasticity's role in the evolution of SSB, we used termites to study how females and males modify their behavior in same-sex versus heterosexual pairs. Male termites follow females in paired "tandems" before mating, and movement patterns are sexually dimorphic. Previous studies observed that adaptive same-sex tandems also occur in both sexes. Here we found that stable same-sex tandems are achieved by behavioral plasticity when one partner adopts the other sex's movements, resulting in behavioral dimorphism. Simulations based on empirically obtained parameters indicated that this socially cued plasticity contributes to pair maintenance, because dimorphic movements improve reunion success upon accidental separation. A systematic literature survey and phylogenetic comparative analysis suggest that the ancestors of modern termites lack consistent sex roles during pairing, indicating that plasticity is inherited from the ancestor. Socioenvironmental induction of ancestral behavioral potential may be of widespread importance to the expression of SSB. Our findings challenge recent arguments for a prominent role of indiscriminate mating behavior in the evolutionary origin and maintenance of SSB across diverse taxa.

SYMBIOTICALLY SNAPPER SHRIMP ANCHISTUS CUSTOIDES BRUCE, 1977 (DECAPODA: PALAEMONIDAE) INHABITING THE MANTLE CAVITY OF THE PEN SHELL (BIVALVIA: PINNIDAE)

Snapper shrimp is a symbiotic organism usually hidden under the rocks, sponges and pen shells in the seagrass and coral habitats. The relationship study within snapper shrimp and pen shell was conducted from Merambong shoal, one of the biggest seagrass beds in peninsular Malaysia. A total of 40 individual pen shells were collected randomly and four species of pen shells were identified. 40 Anchistus custoides were found inhabiting symbiotically in the mantle cavity of the pen shell as solitary males and females and heterosexual pairs. Pen shell, Pinna bicolor and Atrina vexillum recorded the highest average SH 217.79±53.15 mm, SV 2.62±1.36 dm3 and SH 164.10-224.78 mm with the SV 1.18±0.43 dm3, respectively compared to the other species. The size of Anchistus custoides ranged from 15.00 to 20.00 mm in length and it was determined to be female due to the presence of eggs in the pleopods. The length of the cephalothorax and its length were highly related (rs=0.563, p≤0.01, N=40) and found wider in females. A little difference in size between the left and right chela in males of identical length was noticed, although the left chela is much bigger than the right. The significant relationship (rs=0.450, p≤0.01, N=40) between the pen shell length and shrimp (male-female) length revealed that the size of the shell is important to be hosted the snapper shrimp in the shell cavity.

Monogamy in the Burrowing Shrimp Axianassa australis Rodrigues & Shimizu, 1992 (Decapoda, Gebiidea, Axianassidae).

Our knowledge of the mating systems in burrowing shrimps (infraorders Axiidea and Gebiidea) is still rather limited. Here we describe the burrow use pattern, sex ratio, and sexual dimorphism of the burrowing shrimp Axianassa australis to test for monogamy, considering that monogamous species live in heterosexual pairs and exhibit a low degree of sexual dimorphism. To this end, a total of 226 individuals of A. australis were collected from the northeast region of Brazil. Our results showed that A. australis inhabited its burrows mainly as pairs, most of which were male-female pairs. In agreement with the expectations, specimens of A. australis were found dwelling as heterosexual pairs more frequently than expected by chance alone. The presence of ovigerous females was associated with the burrow occupation; that is, brooding females were more frequently observed in male-female combinations than solitarily. Also supporting theoretical considerations, we did not observe sexual dimorphism in body size between males and females of the population and the different categories of the burrow occupation. Conversely, sexual dimorphism in cheliped size was evident in the population, with larger chelipeds in males than in females. This observation agrees with that reported for most burrowing shrimps in which male-male competition is the main evolutionary force of sexual selection. The observations above favor the hypothesis that A. australis is primarily monogamous, with a small fraction of the males moderately promiscuous.

Ideal Men and Dream Women: Computer Matchmaking in twen during the West German Sex Wave, 1967–1970

Abstract Between 1967 and 1970, the West German youth magazine twen embarked on an ambitious experiment to match young heterosexual pairs using computer programming. Named Rendezvous, the program emerged during a moment of particular promise and transformation in West German history. The so-called ‘sex wave’, an emphasis on self-discovery and the reconfiguration of social relationships, had produced both new possibilities and pressures for how young West Germans should ‘get to know’ each other and what they should find meaningful in their romantic relationships. Rendezvous promised to take the guesswork and disappointment out of finding an ideal partner through a rational, scientific assessment of habits, attitudes and desires. This article uses Rendezvous as a lens to examine early interactions between technology, media cultures and value change long before the internet age. Through an analysis of questionnaires, first-person accounts and photo reports, the article argues that Rendezvous evidences the centrality of mass media to the reorganization of courting and romance around notions of personal fulfillment and self-discovery during the late 1960s.

Populational Evidence Supports a Monogomous Mating System in Five Species of Snapping Shrimps of the Genus Alpheus (Caridea: Alpheidae).

The objective of this study was to verify if populations of the snapping shrimps Alpheus angulosus, A. bouvieri, A. carlae, A. estuariensis and A. nuttingi from Pernambuco, northeastern Brazil, are monogamous based on population data. If these species are monogamous, then the populations must exhibit: 1) higher frequency of individuals living in pairs; 2) non-random population distribution, i.e., pairs are found more often than expected by chance alone; 3) males paired with females regardless of their reproductive condition; 4) sexual dimorphism regarding body size and chelipeds weaponry little pronounced among paired individuals and 5) size-assortative pairing. Our samplings were carried out in August 2015, February and August 2016 and February 2017, in the intertidal zone, during low spring tides. We captured a total of 2,276 specimens: 300 of A. angulosus, 393 of A. bouvieri, 374 of A. carlae, 403 of A. nuttingi and 806 of A. estuariensis. The key population parameters (indicators 1, 2, 3, 4, 5 above) for the four species strongly suggest that all four undergo monogomous mating. Although our frequency distribution demonstrated a higher tendency to find solitary individuals in A. nuttingi and A. estuariensis, the other studied features agree with the occurrence of monogamy in those populations. Lastly, the sexual differences observed in the chelipeds and the existence of solitary egg-carrying females indicated that monogamy in the five species is not rigid, i.e., heterosexual pairing may not last long, due to possible competition between males for females or refuge.

Molecular sexing in the formation of pairs of blue-and-yellow macaw (Ara ararauna) in reintroduction programs

Blue and yellow macaw is a species which does not show sexual dimorphism and is threatened by animal traffic. The identification of heterosexual pairs is important for reintroduction programs. The aim of this work was select parameters for sexing and use them to determine the frequency of heterosexual pairs in a population of blue-and-yellow macaws allocated in a Wild Animal Screening Center. Blood samples from 23 macaws were collected and genomic DNA extracted by Tris/SDS washes. Allele-specific molecular markers for sexing were amplified by PCR, and identified on 2% agarose gel. Three pairs of primers were tested: Pair 1 (P2/P8), Pair 2 (1237L/1272H) and Pair 3 (2550F/2718R). For the determination of animal pairs, all individuals had their social behavioral acts observed. The results showed that the low complexity DNA extraction protocol used was adequate. Pairs 2 and 3 of primers were effective for sexing and the Pair 3 was the most efficient. The study also showed that in the sample studied, the composition of males and females was similar (0.4 males n=10 and 0.6 females n=13); 70% (n=16) of the individuals formed pairs and 75% (n=12) of the pairs were heterosexual and the others male-male or female-female pairs. These results were used in the management of the animals in the reintroduction program.

Burrow use and sexual dimorphism as indicators of the mating system in the symbiotic pea crab Austinixa patagoniensis (Rathbun 1918) (Decapoda, Brachyura, Pinnotheridae)

AbstractBrachyuran crabs of the family Pinnotheridae De Haan are a classic example of symbiotic lifestyle. Here, we described the host‐use pattern, relative growth and sexual dimorphism of Austinixa patagoniensis (Rathbun 1918), a symbiont of the ghost shrimp Callichirus major (Say 1818). We use these analyses to test the A. patagoniensis mating system considering that monogamous species inhabit their respective host as male–female pairs and have a low degree of sexual dimorphism. Austinixa patagoniensis showed a high social plasticity, with individuals inhabiting galleries in solitary, in pairs, in trios or in groups of up to eight crabs. While it is true that 38% of the burrows sampled harbored pairs of crabs, the body size of paired crabs from the opposite sex was poorly correlated. This suggests that heterosexual pairing is short term with frequent shifts among burrows by male and/or female crabs, as reported before for other symbiotic decapods in which the body size of paired crabs is poorly correlated. A considerable proportion of the ovigerous females (34%) were found living solitarily, which suggest that males abandon these females shortly after insemination. The sexual dimorphism in terms of body and cheliped size was evident in this species, a condition that argues in favor of male–male competition in A. patagoniensis. The observations above argue against the notion that A. patagoniensis is monogamous. Lastly, our results revealed that body size and chelipeds of males are not under sexual selection by females, thus reinforcing the idea that male–male competition is the mechanism behind sexual selection in A. patagoniensis.

Mating System of the Snapping Shrimp Synalpheus brevicarpus (Caridea, Alpheidae) Inhabiting Sponges Dysidea sp. (Demospongiae).

AbstractThe lifestyle of symbiotic species in the genus Synalpheus can vary from pair living to eusocial. A pair-living social system commonly implies the adoption of a monogamous mating system. In this study, we used the symbiotic shrimp Synalpheus brevicarpus in association with the sponge Dysidea sp. to test the hypothesis that heterosexual pairs of symbiotic shrimps can adopt a monogamous mating system when living in association with a morphologically complex host. We collected a total of 40 sponges, which were inhabited by 76 shrimps: 41 males, 33 females, and 2 juveniles. Synalpheus brevicarpus is sexually dimorphic, with males displaying proportionately larger weaponry (snapping claws) and a smaller average body size than females. Sponges were more often inhabited by a pair of heterosexual shrimps than expected by chance. Larger sponges were inhabited by more than one pair of shrimps in which the sex ratio did not differ significantly from 1∶1. Pairs of heterosexual shrimps were recorded, with females carrying embryos in all stages of embryonic development. Our results indicate that S. brevicarpus is a pair-living shrimp with a monogamous social and mating system that may also guard spaces or areas within its sponge host. Our hypothesis of monogamy is supported by the observations on pair living, sex ratio, and sexual dimorphism in body size and weaponry in this species.

Male Sexual Preference for Female Swimming Activity in the Guppy (Poecilia reticulata).

Simple SummaryIn our first experiment, we found that male and female guppies differ consistently in their swimming activity, both when alone and when together in heterosexual pairs, and that males, regardless of their own activity, show more sexual behaviours to more active females in these pairs. In the second experiment, we gave males the choice between a slow and a fast-moving virtual female and found that males prefer to associate with the fast-moving female. Both experiments together provide evidence that guppy males prefer faster moving females as mating partners over slower moving ones. Higher activity patterns may indicate health, fitness and receptivity and a mating preference for more active females can help males increase their own reproductive success.Mate choice that is based on behavioural traits is a common feature in the animal kingdom. Using the Trinidadian guppy, a species with mutual mate choice, we investigated whether males use female swimming activity—a behavioural trait known to differ consistently among individuals in many species—as a trait relevant for their mate choice. In the first experiment, we assessed male and female activity in an open field test alone (two repeated measures) and afterwards in heterosexual pairs (two repeated measures). In these pairs, we simultaneously assessed males’ mating efforts by counting the number of sexual behaviours (courtship displays and copulations). Male and female guppies showed consistent individual differences in their swimming activity when tested both alone and in a pair, and these differences were maintained across both test situations. When controlling for male swimming behaviour and both male and female body size, males performed more courtship displays towards females with higher swimming activity. In a second experiment, we tested for a directional male preference for swimming activity by presenting males video animations of low- and high-active females in a dichotomous choice test. In congruence with experiment 1, we found males to spend significantly more time in association with the high-active female stimulus. Both experiments thus point towards a directional male preference for higher activity levels in females. We discuss the adaptive significance of this preference as activity patterns might indicate individual female quality, health or reproductive state while, mechanistically, females that are more active might be more detectable to males as well.

Observations of life history traits of Typton carneus Holthuis, 1951 (Caridea, Palaemonidae): a poorly known sponge-dwelling shrimp

The objective of this study was to investigate some life history traits of the palaemonid shrimp Typton carneus collected from a reef in northeastern Brazil. Samples of the sponges Amphimedon compressa, A. viridis, Desmapsamma anchorata, Dysidea etheria, Haliclona implexiformis and Tedania ignis were analyzed and shrimps were removed from them. A total of 41 individuals were found in Te. ignis, three in H. implexiformis and one in D. etheria; the latter two sponges are new records of sponge hosts for Ty. carneus. Of the specimens associated with Te. ignis, 24 were males, 10 ovigerous females, six non-ovigerous females and one juvenile male. Fecundity varied between 19 to 56 eggs (37 ± 14) per female, and the mean egg volume was 0.033 ± 0.010 mm³. Eleven heterosexual pairs were obtained. Characteristics of the pairs suggest a monogamous mating system for the studied population, such as: the absence of sexual dimorphism in weaponry and body size and presence of paired non-brooding and brooding females carrying eggs in different development stages; and a sex ratio that does not differ from the expected 1:1. However, the lack of size-assortative pairing as well as the low proportion of pairs, compared to solitary individuals, have been observed in polygamous mating systems.

Sexual dimorphism in the horn size of a pair-forming coral reef butterflyfish.

Sexual dimorphism is a common in the animal kingdom and is often linked to mate choice or competition for mates in polygynous mating systems. However, sexual dimorphism is less common in species that form heterosexual pairs and has not been recorded in pair-forming coral-reef fish. Here we demonstrate a pronounced morphological difference between males and females in the humphead bannerfish (Heniochus varius)—a pair-forming coral reef butterflyfish. Males of paired individuals collected in Kimbe Bay, Papua New Guinea had substantially larger hump and horn protrusions on their heads than females. Fish were also sexed, sized and aged to determine the reproductive and demographic basis of the pairing behaviour. H. varius pairs were exclusively heterosexual and were assorted strongly by total length and slightly less so by age. Females in pairs were generally the same size as male partners, but were frequently older by a year and sometimes more. Hump and horn lengths increased proportionally to body-size in both sexes, with horns growing at a greater rate among males. These findings suggest that H. varius form pairs primarily for reproductive purposes, with selection via a size-assortative process that likely also extends to selection for larger hump and horn protrusions among males. The larger humps and horns in males appear to be the first recorded example of a secondary sexual morphological characteristic in a pair-forming coral reef fish species.

Hidden burrow associates: macrosymbiotic assemblages of subtidal deep-burrowing invertebrates in the northern part of the Sea of Japan

The activity of deep-burrowing macrofauna strongly influences all biogeochemical processes in sublittoral soft sediments. Despite this key role, these organisms are difficult to sample and, thus, often remain ignored in environmental studies. This study is the first in comprehensively exploring the diversity of the macrosymbiotic communities associated with the dominant subtidal deep-burrowing invertebrates from the southern part of the Russian coast of the Sea of Japan, represented by the species of the genera Upogebia Leach, 1814 (Arthropoda: Crustacea: Decapoda) and Urechis Seitz, 1907 (Annelida: Polychaeta: Echiura). The associated symbiotic communities mostly consist of obligate, host-specific species, while those species found in burrows of both hosts are probably using them just as refuges. Most symbionts occurred solitary or in heterosexual pairs, likely due to aggressive and strictly territorial behavior. This is certainly a hidden biodiversity, as more than half of the species reported here were not previously known from these “relatively simple and well-studied” boreal marine ecosystems. Our findings also allowed us to describe a new species belonging to the symbiotic genus Hesperonoe Chamberlin, 1919 (Annelida: Polychaeta: Polynoidae), based on morphological and molecular evidences, the latter being here presented for this genus for the first time.

Adaptive reshaping of the hormonal phenotype after social niche transition in adulthood

Phenotypic plasticity allows individuals to adjust traits to the environment. Whether long-term adjustments of the phenotype occur during later life stages is largely unknown. To address this question, we examined whether hormonal phenotypes that are shaped by the environment during adolescence can still be reshaped in full adulthood. For this, guinea pig males were either housed in mixed-sex colonies or in heterosexual pairs. In adulthood, males were individually transferred to pair housing with a female. This way, a social niche transition was induced in colony-housed males, but not in pair-housed males. Before transfer, corresponding to findings in adolescence, adult colony-housed males showed significantly higher baseline testosterone levels and lower cortisol responsiveness than pair-housed males. One month after transfer, the hormonal phenotype of colony-housed males was changed towards that of pair-housed males: animals showed comparable baseline testosterone levels and cortisol responsiveness was significantly increased in colony-housed males. This endocrine readjustment builds the basis for an adaptive behavioural tactic in the new social situation. Thus, an adaptive change of the behavioural phenotype may still occur in adulthood via modification of underlying mechanisms. This suggests a greater role for developmental plasticity in later life stages than is commonly presumed.

Sexual and reproductive traits of the pearl oyster shrimp Pontonia margarita (Decapoda: Palemonidae), symbiotically inhabiting the mantle cavity of the rugose pen shell Pinna rugosa (Bivalvia: Pinnidae)

Symbiosis between decapods and mollusks provides a unique opportunity to examine some of the evolutionary strategies employed by marine invertebrates. We describe the sexual and reproductive traits of the pearl oyster shrimp, Pontoniamargarita Verril, 1869, found symbiotically inhabiting the mantle cavity of the rugose pen shell, Pinnarugosa Sowerby, 1835. Solitary males and females (ovigerous and non-ovigerous) and heterosexual pairs (with ovigerous and non-ovigerous females) were found in a total of 47 rugose pen shells collected from a sandy area with seagrass meadows on the southeastern coast of the Gulf of California, Mexico. The body length (BL) of female P.margarita was correlated with the shell volume of their rugose pen shell host. The sex ratio was female-biased (0.85M:1F). Female P.margarita were larger than their male counterparts in terms of BL, cephalothorax length (CL), and the maximum chelae length of the second pereopod (MCL). The CL and MCL were more strongly correlated for males (r = 0.70, p = 0.01). The number and volume of eggs per ovigerous female varied from 95 to 1,571 and from 5.46 ± 0.48 to 8.85 ± 0.97 mm3, respectively. Our results indicate polygamous behavior and social monogamy among P.margarita, and a short-term pairing system for their association with P.rugosa.

A new species of pea crab from south-western Europe (Crustacea, Decapoda, Brachyura): species description, geographic distribution and population structure with an identification key to European Pinnotheridae

AbstractAfter the recent detection, by both morphology and DNA barcodes, of the larval stages of an unknown species of pea crab (Pinnotheres sp.) in European waters, adults of this crab are herein reported and described as a new species. The current known geographic distribution of the species comprises the Gulf of Cádiz in the eastern Atlantic and the adjacent Mediterranean waters of the south of the Iberian Peninsula (Alboran Sea), where this crab is well-established inside the anomiid bivalve Anomia ephippium. In the Gulf of Cádiz, the species displayed a relatively high prevalence: on average, 55.6–77.7%, in A. ephippium samples. The dominant demographic categories of the new species were soft females (61.8–77.0%) with fewer males (17.7–21.10%). Most of the host bivalves carried only one crab; in bivalves harbouring two crabs, heterosexual pairs were collected more frequently than expected by chance, which suggests that they could be mated pairs. A strong correlation between host size and soft female size was found (r = 0.73, P < 0.01) indicating that space availability within hosts seems to be relevant in determining the size of the sedentary phase of the new crab species.

A new species of Polyonyx (Crustacea, Anomura, Porcellanidae) inhabiting polychaete-worm tubes (Annelida, Chaetopteridae) in the Indo-West Pacific.

Polyonyxsocialissp. n. from the South China Sea of Vietnam is described. The new species was collected in a previous study that compared the vertebrate and invertebrate symbiont communities living in the tubes of two syntopic species of the polychaete genus Chaetopterus. Polyonyxsocialissp. n. inhabits the tubes of the smaller polychaete species as a heterosexual pair, and frequently shares the cavity of the host’s tube with a larger porcellanid, P.heok, also present as a male-female pair, and with a species of trinchesiid nudibranch. Less frequently, the new species shares its host with a heterosexual pair of a larger species of pinnotherid crab. Polyonyxsocialissp. n. belongs to the P.sinensis group, a world-wide distributed morphological line within the heterogeneous genus Polyonyx. Most species in this group are obligate commensals of chaetopterid polychaetes. The crabs have a transversally cylindrical habitus, which enables them to move laterally along the worm tubes with ease. Polyonyxsocialissp. n. is a relatively small species that lives attached to the inner walls of the polychaete tube. The small size and flattened chelipeds and walking legs of the new species confers it an advantage to cohabiting the same worm tube with larger decapod species occupying most of the tube’s cavity.

Phylogenetic Methods Inconsistently Predict the Direction of HIV Transmission Among Heterosexual Pairs in the HPTN 052 Cohort.

We evaluated use of phylogenetic methods to predict the direction of human immunodeficiency virus (HIV) transmission. For 33 pairs of HIV-infected patients (hereafter, "index patients") and their partners who acquired genetically linked HIV infection during the study, samples were collected from partners and index patients close to the time when the partner seroconverted (hereafter, "SC samples"); for 31 pairs, samples collected from the index patient at an earlier time point (hereafter, "early index samples") were also available. Phylogenies were inferred using env next-generation sequences (1 tree per pair/subtype). The direction of transmission (DoT) predicted from each tree was classified as correct or incorrect on the basis of which sequences (those from the index patient or the partner) were closest to the root. DoT was also assessed using maximum parsimony to infer ancestral node states for 100 bootstrap trees. DoT was predicted correctly for both single-pair and subtype-specific trees in 22 pairs (67%) by using SC samples and in 23 pairs (74%) by using early index samples. DoT was predicted incorrectly for 4 pairs (15%) by using SC or early index samples. In the bootstrap analysis, DoT was predicted correctly for 18 pairs (55%) by using SC samples and for 24 pairs (73%) by using early index samples. DoT was predicted incorrectly for 7 pairs (21%) by using SC samples and for 4 pairs (13%) by using early index samples. Phylogenetic methods based solely on the tree topology of HIV env sequences, particularly without consideration of phylogenetic uncertainty, may be insufficient for determining DoT.

Investigating parental care behaviour in same-sex pairing of zoo greater flamingo (Phoenicopterus roseus).

Same-sex pair bonds have been documented in several animal species and they are widespread in birds. However, little is known about the evolutionary origin and the adaptive value of such behaviour. The aim of this study was to investigate the parental behaviour of four zoo female greater flamingos involved in two breeding pairs, housed in a flock at Parco Natura Viva, Italy. Further, the behaviour of the study females was compared with that of male and female flamingos in heterosexual pairs described in a previous published work on this same flock. For each pair, the behaviour of both birds during the incubation period was recorded and twenty 10-minute sessions were run within the incubation period. A continuous focal animal sampling method was used to collect data on location (on the nest or not on the nest) and the parental care behaviour (e.g.: agonistic behaviours toward disturbing conspecifics, egg-care, nest-building, self-comfort behaviour, sleeping) of the two pairs. Data of the current study females were compared with those of females and males involved in heterosexual pairs of this same flock. Results showed that within each pair the egg-layer female stayed away from the nest more than the other female. In addition, the female that did not lay an egg was more involved in agonistic behaviour compared to other females, particularly when in specific locations. In heterosexual pairs, male flamingos were more involved in the incubation and in nest protection. Moreover, no significant differences in the time spent on the nest and away from the nest between the heterosexual male and the non-layer females of same-sex pairs were found. The same findings were reported when comparing heterosexual females and the egg-layer females of the same-sex pairs. Therefore, our findings suggest that in greater flamingos the behaviour of the female–female pairs seems to be equivalent to that of male-female bonds. Such research provides more insight into flamingo social behaviour, and their reproductive cycle, and provides information on why pair bonds may form and how these affect the wider breeding behaviour of the flock.