Baby on board: olfactory cues indicate pregnancy and fetal sex in a non-human primate.

Olfactory cues play an integral, albeit underappreciated, role in mediating vertebrate social and reproductive behaviour. These cues fluctuate with the signaller's hormonal condition, coincident with and informative about relevant aspects of its reproductive state, such as pubertal onset, change in season and, in females, timing of ovulation. Although pregnancy dramatically alters a female's endocrine profiles, which can be further influenced by fetal sex, the relationship between gestation and olfactory cues is poorly understood. We therefore examined the effects of pregnancy and fetal sex on volatile genital secretions in the ring-tailed lemur (Lemur catta), a strepsirrhine primate possessing complex olfactory mechanisms of reproductive signalling. While pregnant, dams altered and dampened their expression of volatile chemicals, with compound richness being particularly reduced in dams bearing sons. These changes were comparable in magnitude with other, published chemical differences among lemurs that are salient to conspecifics. Such olfactory 'signatures' of pregnancy may help guide social interactions, potentially promoting mother-infant recognition, reducing intragroup conflict or counteracting behavioural mechanisms of paternity confusion; cues that also advertise fetal sex may additionally facilitate differential sex allocation.

Phytochrome diversity in green plants and the origin of canonical plant phytochromes.

Phytochromes are red/far-red photoreceptors that play essential roles in diverse plant morphogenetic and physiological responses to light. Despite their functional significance, phytochrome diversity and evolution across photosynthetic eukaryotes remain poorly understood. Using newly available transcriptomic and genomic data we show that canonical plant phytochromes originated in a common ancestor of streptophytes (charophyte algae and land plants). Phytochromes in charophyte algae are structurally diverse, including canonical and non-canonical forms, whereas in land plants, phytochrome structure is highly conserved. Liverworts, hornworts and Selaginella apparently possess a single phytochrome, whereas independent gene duplications occurred within mosses, lycopods, ferns and seed plants, leading to diverse phytochrome families in these clades. Surprisingly, the phytochrome portions of algal and land plant neochromes, a chimera of phytochrome and phototropin, appear to share a common origin. Our results reveal novel phytochrome clades and establish the basis for understanding phytochrome functional evolution in land plants and their algal relatives.

The Roles of Phenotypic Plasticity and Plant-Microbe Interactions in the Evolution of Complex Traits in Boechera stricta

All organisms live in complex habitats that shape the course of their evolution by altering the phenotype expressed by a given genotype (a phenomenon known as phenotypic plasticity) and simultaneously by determining the evolutionary fitness of that phenotype. In some cases, phenotypic evolution may alter the environment experienced by future generations. This dissertation describes how genetic and environmental variation act synergistically to affect the evolution of glucosinolate defensive chemistry and flowering time in Boechera stricta, a wild perennial herb. I focus particularly on plant-associated microbes as a part of the plant’s environment that may alter trait evolution and in turn be affected by the evolution of those traits. In the first chapter I measure glucosinolate production and reproductive fitness of over 1,500 plants grown in common gardens in four diverse natural habitats, to describe how patterns of plasticity and natural selection intersect and may influence glucosinolate evolution. I detected extensive genetic variation for glucosinolate plasticity and determined that plasticity may aid colonization of new habitats by moving phenotypes in the same direction as natural selection. In the second chapter I conduct a greenhouse experiment to test whether naturally-occurring soil microbial communities contributed to the differences in phenotype and selection that I observed in the field experiment. I found that soil microbes cause plasticity of flowering time but not glucosinolate production, and that they may contribute to natural selection on both traits; thus, non-pathogenic plant-associated microbes are an environmental feature that could shape plant evolution. In the third chapter, I combine a multi-year, multi-habitat field experiment with high-throughput amplicon sequencing to determine whether B. stricta-associated microbial communities are shaped by plant genetic variation. I found that plant genotype predicts the diversity and composition of leaf-dwelling bacterial communities, but not root-associated bacterial communities. Furthermore, patterns of host genetic control over associated bacteria were largely site-dependent, indicating an important role for genotype-by-environment interactions in microbiome assembly. Together, my results suggest that soil microbes influence the evolution of plant functional traits and, because they are sensitive to plant genetic variation, this trait evolution may alter the microbial neighborhood of future B. stricta generations. Complex patterns of plasticity, selection, and symbiosis in natural habitats may impact the evolution of glucosinolate profiles in Boechera stricta.

The Perspectives of Gay, Bisexual, and Queer Adolescent Males with Parent-Child Sex Communication

Problem: Gay, bisexual, and queer (GBQ) adolescent males are disproportionately affected by negative sexual health outcomes compared to their heterosexual counterparts. Their sex education needs are not sufficiently addressed in the home and the larger ecological systems. The omission of their sex education needs at a time when they are forming a sexual identity during adolescence compels GBQ males to seek information in unsupervised settings. Evidence-based interventions aimed at ensuring positive sexual health outcomes through sex communication cannot be carried out with these youth as research on how parents and GBQ males discuss sex in the home has been largely uninvestigated.

Methods: This naturalistic qualitative study focused on the interpretive reports of 15- to 20-year-old GBQ males’ discussions about sex-related topics with their parents. From a purposive sample of 30 male adolescents who self-identified as GBQ, participants who could recall at least one conversation about sex with their parents were recruited for one-time interviews and card sorts. This strategy revealed, using Bronfenbrenners’ Bioecological Theory, their perceptions about sex communication in the context of their reciprocal relationship and the ecological systems that GBQ males and their parents navigate.

Results: Parents received poor ratings as sex educators, were generally viewed as not confident in their communication approach, and lacked knowledge about issues pertinent to GBQ sons. Nevertheless, participants viewed parents as their preferred source of sex information and recognized multiple functions of sex communication. The value placed by GBQ youth on sex communication underscores their desire to ensure an uninterrupted parent-child relationship in spite of their GBQ sexual orientation. For GBQ children, inclusive sex communication is a proxy for parental acceptance.

Results show that the timing, prompts, teaching aids, and setting of sex communication for this population are similar to what has been reported with heterosexual samples. However, most GBQ sons rarely had inclusive guidance about sex and sexuality that matched their attraction, behavior, and identities. Furthermore, the assumption of heterosexuality resulted in the early awareness of being different from their peers which led them to covertly search for sex information. The combination of assumed heterosexuality and their early reliance on themselves for applicable information is a missed parental opportunity to positively impact the health of GBQ sons. More importantly, due to the powerful reach of new media, there is a critical period of maximum receptiveness that has been identified which makes inclusive sex communication paramount in the pre-sexual stage for this population. Our findings also indicate that there are plenty of opportunities for systemic improvements to meet this population’s sexual education needs.