Homosexual behavior in primates: A review of evidence and theory

Homosexual behavior is defined as genital contact, genital manipulation or both between same-sex individuals. Available data indicate that this behavior is phylogenetically widespread among the anthropoid primates, but totally absent among prosimians. The majority of the 33 species that demonstrate homosexual behavior do so rarefy, but for a substantial number (N =12) it appears to be a more common pattern under free-ranging conditions. I summarize data on homosexual behavior as it relates to form, living condition, age, sex, social organization, and ecological context, and discuss hormonal, demographic, and sociosexual theories for primate homosexual behavior. Among adult primates, the behavior is not the product of abnormal excesses or deficiencies in androgens. Prenatal excesses of androgens may have some effect on the expression of female homosexual behavior, but these effects might vary over the life span, and data are equivocal at present. Demographic processes that result in skewed sex ratios can favor the expression of homosexual behavior in a population, which causes intraspecific variation. I examine several sociosexual explanations, including (a) proceptivity enhancement, (b) receptivity reduction, (c) dominance assertion, (d) practice for heterosexual copulation, (e) tension regulation, (f) reconciliation, and (g) alliance formation. An evolutionary scenario highlights the transformations this behavior underwent during the evolution of the anthropoid primates. I suggest exaptation as a theoretical framework for interpreting homosexual behavior and conclude that future consideration of sexual selection among primates should address homosexual components of this process.     

Mounting Interactions between Female Japanese Macaques: Testing the Influence of Dominance and Aggression

The goal of the work reported here was to determine whether female Japanese macaques (Macaca fuscata) participated in same-sex mounting interactions during homosexual consortships to communicate about asymmetries in their dominance relationships and to reduce aggression. Focal data were collected during 21 homosexual consortships involving 14 females living in a captive, mixed-sex group of 37 individuals. We identified eight types of mounts, one solicitation used specifically to request to mount (hands-on-hindquarters solicitation), two solicitations used specifically to request to be mounted (hindquarter and back presentations), and one behavior employed to facilitate mounts-in-progress (clasping). We tested whether dominant consort partners (1) mounted more and (2) requested to mount more than their subordinate partners and whether subordinate consort partners (1) requested to be mounted more and (2) facilitated mounts-in-progress more than their dominant partners. Finally, we examined whether mounting was temporally linked to the onset of aggressive interactions between consort partners and whether it functioned to defuse incipient aggression. None of these predictions was supported. All types of mounts, mount solicitations, and clasping occurred bi-directionally within consort dyads. Mutual sexual attraction and gratification provided the proximate motivation for these mounting interactions and, in turn, for the formation and maintenance of their homosexual consortships.     

Single-Cell Protein

The unlimited proliferative ability and plasticity to generate other cell types ensures that stem cells represent a dynamic system apposite for the identification of new molecular targets and the production and development of novel drugs. These cell lines derived from embryos could be used as a model for the study of basic and applied aspects in medical therapeutics, environmental mutagenesis and disease management. As a consequence, these can be tested for safety or to predict or anticipate potential toxicity in humans. Human ES cell lines may, therefore, prove clinically relevant to the development of safer and more effective drugs for patients presenting with diabetes mellitus.

These findings substantiate our method of encapsulation as opposed to the traditional formation strategies, for example those described by Cameron et al, where embryoid body formation is required (Hu 2003; Cameron 2006). These systems are probably used because they are known to generate three germ layers characteristic of embryo development, but EB formation is not an essential requirement in the production of insulin.     

Artificial bare patches increase habitat for the endangered Ohlone tiger beetle (Cicindela ohlone)

The endangered Ohlone tiger beetle (Cicindela ohlone) depends on bare ground areas in California coastal grasslands to encounter mates, oviposit, and find prey. We tested habitat creation as a potential management strategy to increase the availability of oviposition sites for C. ohlone. We compared three different bare ground treatments by scraping off surface vegetation, ripping, and tamping the plots. We also tested whether bare ground creation expands C. ohlone range within a habitat patch by scraping plots at increasing distances from the core habitat and monitoring C. ohlone colonization. C. ohlone oviposited significantly more in artificial bare ground plots compared to controls both one and 2 years after the scrapes were created. Distance from the core habitat did not affect colonization nor did decompaction of scraped plots. Percent bare ground significantly predicted incidence of colonization. For the conservation of the endangered Ohlone tiger beetle, we recommend continued creation of scraped plots every 2 years in order to maintain bare ground and to ensure maximum usage by female C. ohlone as oviposition sites.     

Sex differences in sexual partner acquisition, retention, and harassment during female homosexual consortships in Japanese macaques

Female Japanese macaques (Macaca fuscata) in certain populations are unusual in that they exhibit male-typical patterns of mounting behavior and sexual-partner preference. The goal of this study was to determine whether female Japanese macaques, from one such population, employ male-typical behavioral tactics to disrupt existing homosexual consortships, as well as to acquire and retain same-sex sexual partners. "Harassment" of homosexual consortships occurred when a sexually motivated, third-party male or female interrupted a consorting female couple by displacing or aggressing them. Sexual harassment was a male-typical strategy for disrupting existing homosexual consortships, but was rarely performed by females. "Intrusions" occurred when a male or female competitor attempted to acquire exclusive access to a female engaged in a homosexual consortship by targeting that female as the focus of competition and her partner as his/her competitor. "Sexual coercion" occurred when one individual alternately sexually solicited and aggressed another individual as part of the same behavioral sequence during an intrusion. Males employed consortship intrusions and sexual coercion when they attempted to acquire female sexual partners that were already engaged in homosexual consortships, but females rarely did so. However, females did employ male-typical patterns of aggressive competition and sexual coercion to retain same-sex sexual partners when confronted with male competitors' attempts to usurp those partners. These results indicate that female sexual activity during homosexual consortships is not uniformly "masculine" in expression, but rather is a mixture of male- and female-typical behaviors.     

Niche separation in Varecia variegata rubra and Eulemur fulvus albifrons: I. Interspecific patterns

Niche separation was documented in a year-long study of Varecia variegata rubra and Eulemur fulvus albifrons on the Masoala Peninsula, Madagascar. Feeding trees were measured, and diet, forest height, and forest site were recorded at 5-min time points on focal animals. For time point data, multivariate and bivariate analysis of frequencies was employed to examine how niche dimensions vary between species according to sex, season, and reproductive stage. V. v. rubra feeds in larger trees than E. f. albifrons. V. v. rubra has a diet consisting mainly of fruit, whereas E. f. lbifrons has a more varied diet. V. v. ubra ranges mainly above 15 m in tree crowns, whereas E. f. albifrons ranges mainly below 15 m in a wide array of forest sites. Both species are largely frugivorous, but they harvest fruit in different-sized trees, in different quantities, and in different forest strata. Niche partitioning varies in tandem with seasonal shifts in climate and food availability and with reproductive stages. Seasonal shifts in forest site and forest height use are largely attributed to species-specific tactics for behavioral thermoregulation and predator avoidance. The diet of E. f. albifrons is diverse whether examined by season or reproductive stage. However, females of both species diversify their diets with more low-fiber protein than males during gestation, lactation, and the hot seasons. This pattern is most pronounced for V. v. rubra females and may be directly attributed to high energetic investment in reproduction. These results suggest that niche partitioning may be driven more by the energetic requirements of reproductive females than males.     

Maritime climate influence on chaparral composition and diversity in the coast range of central California

We investigated the hypothesis that maritime climatic factors associated with summer fog and low cloud stratus (summer marine layer) help explain the compositional diversity of chaparral in the coast range of central California. We randomly sampled chaparral species composition in 0.1‐hectare plots along a coast‐to‐interior gradient. For each plot, climatic variables were estimated and soil samples were analyzed. We used Cluster Analysis and Principle Components Analysis to objectively categorize plots into climate zone groups. Climate variables, vegetation composition and various diversity measures were compared across climate zone groups using ANOVA and nonmetric multidimensional scaling. Differences in climatic variables that relate to summer moisture availability and winter freeze events explained the majority of variance in measured conditions and coincided with three chaparral assemblages: maritime (lowland coast where the summer marine layer was strongest), transition (upland coast with mild summer marine layer influence and greater winter precipitation), and interior sites that generally lacked late summer water availability from either source. Species turnover (β‐diversity) was higher among maritime and transition sites than interior sites. Coastal chaparral differs from interior chaparral in having a higher obligate seeder to facultative seeder (resprouter) ratio and by being dominated by various Arctostaphylos species as opposed to the interior dominant, Adenostoma fasciculatum. The maritime climate influence along the California central coast is associated with patterns of woody plant composition and β‐diversity among sites. Summer fog in coastal lowlands and higher winter precipitation in coastal uplands combine to lower late dry season water deficit in coastal chaparral and contribute to longer fire return intervals that are associated with obligate seeders and more local endemism. Soil nutrients are comparatively less important in explaining plant community composition, but heterogeneous azonal soils contribute to local endemism and promote isolated chaparral patches within the dominant forest vegetation along the coast.     

Genetic dissection of Al tolerance QTLs in the maize genome by high density SNP scan

Background

Aluminum (Al) toxicity is an important limitation to food security in tropical and subtropical regions. High Al saturation on acid soils limits root development, reducing water and nutrient uptake. In addition to naturally occurring acid soils, agricultural practices may decrease soil pH, leading to yield losses due to Al toxicity. Elucidating the genetic and molecular mechanisms underlying maize Al tolerance is expected to accelerate the development of Al-tolerant cultivars.

Results

Five genomic regions were significantly associated with Al tolerance, using 54,455 SNP markers in a recombinant inbred line population derived from Cateto Al237. Candidate genes co-localized with Al tolerance QTLs were further investigated. Near-isogenic lines (NILs) developed for ZmMATE2 were as Al-sensitive as the recurrent line, indicating that this candidate gene was not responsible for the Al tolerance QTL on chromosome 5, qALT5. However, ZmNrat1, a maize homolog to OsNrat1, which encodes an Al³⁺ specific transporter previously implicated in rice Al tolerance, was mapped at ~40 Mbp from qALT5. We demonstrate for the first time that ZmNrat1 is preferentially expressed in maize root tips and is up-regulated by Al, similarly to OsNrat1 in rice, suggesting a role of this gene in maize Al tolerance. The strongest-effect QTL was mapped on chromosome 6 (qALT6), within a 0.5 Mbp region where three copies of the Al tolerance gene, ZmMATE1, were found in tandem configuration. qALT6 was shown to increase Al tolerance in maize; the qALT6-NILs carrying three copies of ZmMATE1 exhibited a two-fold increase in Al tolerance, and higher expression of ZmMATE1 compared to the Al sensitive recurrent parent. Interestingly, a new source of Al tolerance via ZmMATE1 was identified in a Brazilian elite line that showed high expression of ZmMATE1 but carries a single copy of ZmMATE1.

Conclusions

High ZmMATE1 expression, controlled either by three copies of the target gene or by an unknown molecular mechanism, is responsible for Al tolerance mediated by qALT6. As Al tolerant alleles at qALT6 are rare in maize, marker-assisted introgression of this QTL is an important strategy to improve maize adaptation to acid soils worldwide.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-153) contains supplementary material, which is available to authorized users.     

Monetary exchanges with nieces and nephews: a comparison of Samoan men,women, and fa'afafine

Androphilia refers to sexual attraction and arousal to adult males, whereas gynephilia refers to sexual attraction and arousal to adult females. The kin selection hypothesis for male androphilia suggests that androphilic males have been selected to act as “helpers-in-the-nest,” caring for nieces and nephews and, by extension, increasing their indirect fitness. Previous research has demonstrated that Samoan male androphiles (known locally as fa'afafine) exhibit significantly higher altruistic tendencies toward nieces and nephews compared to Samoan women and gynephilic men. Elevated avuncular tendencies must translate into real-world avuncular behavior if they are to have any impact on the fitness of nieces and nephews and the uncles themselves. The present study examined whether Samoan fa'afafine exhibit higher altruistic behavior toward nieces and nephews compared to women and gynephilic men. We used money given to, and received from, oldest and youngest siblings' sons and daughters as a behavioral assay of kin altruism. Compared to women and gynephilic men, fa'afafine gave significantly more money to their youngest siblings' daughters. No group differences were observed for money received from nieces and/or nephews. There were no correlations between number of children parented and monetary exchanges with the niece and nephew categories examined, suggesting that childlessness cannot account for why fa'afafine give more money to their youngest siblings' daughters. These findings are consistent with the kin selection hypothesis for male androphilia.     

Genetic architecture of two red ruffed lemur (<Emphasis Type="Italic">Varecia rubra</Emphasis>) populations of Masoala National Park

The current range of the red ruffed lemur (Varecia rubra) population is primarily restricted to forests of the Masoala Peninsula on the northeastern coast of Madagascar. Whereas much of the peninsula is protected as Masoala National Park, parts of the forest are at risk from anthropogenic pressures and habitat fragmentation. We sampled 32 individual red ruffed lemur from two sites: Ambatoledama (DAMA), a narrow forest corridor across an area of degraded habitat connecting larger blocks of forest in the northwestern reaches of the park, and Masiaposa (MAS) forest, a largely pristine forest on the lower western side of the peninsula. Population genetic parameters were estimated for these two populations employing 15 microsatellite loci derived from the V. variegata genome. We found that by exceeding the expected heterozygosity at mutation-drift equilibrium, the DAMA population has undergone a recent population bottleneck. Population structure analysis detected individuals harboring genotypic admixture of the DAMA genetic cluster in the MAS population, suggesting a possibility of unilateral gene flow or movement between these populations.