On the Origin of the Family

This paper presents an overlapping generations model to explain why humans live in families rather than in other pair groupings. Since most non-human species are not familial, something special must be behind the family. It is shown that the two necessary features that explain the origin of the family are given by uncertain paternity and overlapping cohorts of dependent children. With such two features built into our model, and under the assumption that individuals care only for the propagation of their own genes, our analysis indicates that fidelity families dominate promiscuous pair bonding, in the sense that they can achieve greater survivorship and enhanced genetic fitness. The explanation lies in the free riding behavior that characterizes the interactions between competing fathers in the same promiscuous pair grouping. Kin ties could also be related to the emergence of the family. When we consider a kinship system in which an adult male transfers resources not just to his offspring but also to his younger siblings, we find that kin ties never emerge as an equilibrium outcome in a promiscuous environment. In a fidelity family environment, instead, kinship can occur in equilibrium and, when it does, it is efficiency enhancing in terms of greater survivorship and fitness. The model can also be used to shed light on the issue as to why virtually all major world religions are centered around the importance of the family.fatherhood uncertainty, free riding, kinship systems, religion, overlapping generations, divorce and blended families

Gene regulatory evolution and the origin of complex behaviors in the prairie vole, Microtus ochrogaster

Understanding variation in form and behavior within and among species requires mapping genotypes to phenotypes. Much of this variation depends on differences in regulatory DNA scattered throughout the genome; in the context of behavior, these regulatory sequences govern gene expression in regions of the brain that shape behavior. Surprisingly few studies have characterized the regulatory changes that underlie the adaptive evolution of brain and behavior. In my PhD dissertation project, I investigated the adaptive role of gene regulation in the evolution of pair-bonding and sexual fidelity in the prairie voles, Microtus ochrogaster. Expression of Avpr1a in the ventral pallidum plays a critical role in the origin and evolution of pair-bonding in these monogamous voles. In Chapter 1, I have applied phylogenetic and population genetic methods to find signatures of selection in functional elements in the prairie vole genome. I identified a regulatory element of the Avpr1a locus that is under positive selection, this sequence coincides with the origins of expression of this gene in a reward region, the ventral pallidum. Then, I tested its causality using transgenic mouse enhancer assays. I found that transgenic mice expressing a reporter under the control of this prairie vole enhancer were able to drive expression in the ventral pallidum, but expression was sensitive to insertion site. Interestingly, this gene also shows profound differences between individuals. In Chapter 2, I applied population genomic tools to demonstrate that this locus shows signatures of balancing selection in a polymorphic enhancer that predicts expression in a spatial memory circuit. I found that alleles that predict aspects of space use and sexual fidelity are strongly linked to each other. Moreover, I show evidence that the evolution of this regulatory element seems to be mediated by a mix of balancing, epistatic and density-dependent selection. In Chapter 3, I performed RNA-sequencing experiments to analyze monogamy-related genomic changes in the brain. I found massive changes in gene expression of prairie voles in contrast to promiscuous meadow voles, despite their gene expression modules are very well preserved. Moreover, neuroplasticity –a neural process involved with learning— was strongly activated in prairie but not it meadow vole brains. Overall, the results of these experiments reveal the potential for gene regulation to drive the adaptive evolution of complex behaviors.Ecology, Evolution and Behavio

On the origin of the family

We present a game theoretic model to explain why people form life long monogamous families. Three components are essential in our framework, paternal investment, fatherhood uncertainty, and, perhaps the most distinctive feature of all, the overlap of children of different ages. When all three conditions are present, monogamy is the most efficient form of sexual organization in the sense that it yields greater survivorship than serial monogamy, group marriage, and polygyny. Monogamy is also the only configuration that fosters altruistic ties among siblings. Finally, our result sheds light to the understanding of why most religions center around the monogamous fidelity family

Physical separation from the mate diminishes male’s attentiveness towards other females: a study in monogamous prairie voles Microtus ochrogaster

We tested whether continuous cohabitation in monogamous voles affects the mated male’s attentiveness to his breeding partner versus another female. Each male was housed in a 3-chamber apparatus with a Focal female (FF) and a Control female (CF) for 13 days then placed in a T-maze to assess his attentiveness to and memory of those females. The Distal male remained physically separated from both females, but received their distal cues. The Separate male cohabited with the FF for 3 days then remained physically separated from both females. The Disrupt male’s continuous cohabitation with the FF was disrupted by having him physically separated from her after 10 days and placed with the CF for the last 3 days. The Continuous male cohabited continuously with the FF for 13 days. With females in the T-maze, the Separate and Disrupt males spent more time near the FF’s box and the Disrupt males spent more time manipulating the FF’s box than the CF’s box. The Separate males groomed themselves more when near the FF’s box than the CF’s box. The Distal and Continuous males’ attentiveness to the two females did not differ. Results suggest that physical distance from the partner may reduce male’s attentiveness toward other potential mates. Prairie voles might be similar to socially monogamous primates in using tactile cues as a signal for maintaining their social bonds

Pair Bonds In Genetic Algorithm

Tesis ini membentangkan siasatan komprehensif berasaskan konsep ikatan pasangan (pasangan monogami) yang akan dilaksanakan dalam fasa rekombinasi algoritma genetik (GA). GA merupakan teknik pencarian heuristik berdasarkan prinsip dan mekanisma pilihan semula jadi dan teori "survival of the fittest". Biasanya kromosom ibubapa akan dipilih pada setiap generasi bagi menghasilkan kromosom anak melalui operasi percantuman (crossover) dan mutasi. Proses ini diulangi sehingga syarat berhenti dipenuhi. Tetapi kadang-kala alam semula jadi mempamerkan pembentukan hubungan yang berkekalan antara pasangan mengawan. Dalam masyarakat manusia moden, sesetengah burung, ikan, tikus, dan cicak, ikatan pasangan merupakan aspek penting dalam tingkah laku sosial mereka. Mereka biasanya mengekalkan pasangan yang sama sepanjang hidup - monogami sosial. Oleh itu, tesis ini mengkaji kesesuaian aplikasi ikatan pasangan dalam GA. Dua kaedah GA baru akan dibentangkan: Kaedah pertama dikenali sebagai Algoritma Genetik Ikatan Monogami (MopGA). Dalam MopGA, kromosom ibubapa akan berkekalan sehingga beberapa generasi. This work presents a comprehensive investigation on the concept of pair bonds (monogamous pairs) for the mating phase of genetic algorithms (GAs). GA is a heuristic search technique based on the principles and mechanisms of natural selection. Traditionally, parents are selected at every generation to reproduce offspring through crossover and mutation operations. The process reiterates until some termination conditions are met. However, nature sometimes exhibits the formation of enduring relationships between mating partners. In modern human society, some avian models, fish, rodents, and even lizards, pair bonds are integral aspects of their social behaviour. These species usually share the same mating partners throughout their lifetime - socially monogamous. Taking the cue from nature, this thesis studies the feasibilities of pair bonds in GA. Consequently, two methodologies are proposed: Firstly, in the Monogamous Pairs Genetic Algorithm (MopGA), parents are bonded and mated consistently over several predefined generations. Selection of new parents pairs will only take place at the end of pair bond tenure. Meanwhile, competition occurs between siblings to ensure only the best offspring are retained. Occasional infidelity generates variety, spreads genetic information across the population and speeds up convergence. Secondly, to improve the ease-of-use of MopGA, an adaptive MopGA (AMopGA) is introduced

On the Origin of the Family

This paper presents an overlapping generations model to explain why humans live in families rather than in other pair groupings. Since most non-human species are not familial, something special must be behind the family. It is shown that the two necessary features that explain the origin of the family are given by uncertain paternity and overlapping cohorts of dependent children. With such two features built into our model, and under the assumption that individuals care only for the propagation of their own genes, our analysis indicates that fidelity families dominate promiscuous pair bonding, in the sense that they can achieve greater survivorship and enhanced genetic fitness. The explanation lies in the free riding behavior that characterizes the interactions between competing fathers in the same promiscuous pair grouping. Kin ties could also be related to the emergence of the family. When we consider a kinship system in which an adult male transfers resources not just to his offspring but also to his younger siblings, we find that kin ties never emerge as an equilibrium outcome in a promiscuous environment. In a fidelity family environment, instead, kinship can occur in equilibrium and, when it does, it is efficiency enhancing in terms of greater survivorship and fitness. The model can also be used to shed light on the issue as to why virtually all major world religions are centered around the importance of the family

Molecular Evolution of Vasopressin and Oxytocin Receptor Genes in Owl Monkeys (aotus Azarai) of Northern Argentina

The arginine vasopressin (AVP) and oxytocin (OT) hormone pathways are involved in a multitude of physiological processes, and their receptor genes (AVPR1A and OXTR) have been implicated in increased partner preference and pair bonding behavior in mammalian lineages. This observation is of considerable importance for understanding social monogamy in primates, which is present in only a small subset of primate taxa, including Azara\u27s owl monkeys (Aotus azarai). Thus, it is the goal of this dissertation to examine the molecular evolution of AVPR1A and OXTR in owl monkeys to better understand how the pro-social behaviors related to those loci may have evolved. However, in order to properly contextualize functional neurogenetic variation related to such sociobehavioral pattterns, it is necessary to first establish the range of molecular variation occurring at non-related genetic loci. To address this issue, we sequenced the entire mitochondrial genome of two species of Aotus (A. azarai and A. nancymaae), and analyzed 39 haplotypes of the mitochondrial COII gene from ten different owl monkey taxa. Next, to understand the recent evolutionary history and genetic structure of our focal owl monkey population, we assessed variation of the mtDNA control region (D-loop) in 118 wild individuals. Furthermore, to establish our knowledge of genetic kinship and individual identity within the wild population, we investigated autosomal variation in the form of 24 short tandem repeat (STR) microsatellite loci. In concert with these analyses, we characterized the molecular features of AVPR1A and OXTR in A. azarai and other platyrrhines through direct sequencing, and demonstrated that there are substantial sequence differences at both loci across primate species. These data provide new clues on the possible basis of pair bonding in New World species, and may help to explain the sporadic appearance of monogamy in this infraorder. Specifically, despite a common molecular origin, we argue that the AVP and OT pathways have evolved in markedly different ways, due in part to their chromosomal locations and their relative proximity to regions of molecular instability. This study reinforces the notion that neurogenetic loci in primates have undergone significant evolutionary changes, and suggests that monogamy has arisen multiple times in the primate order through different molecular mechanisms

Unravelling mechanisms of reproductive isolation between two sister species of iberian voles

Tese de doutoramento, Biologia (Evolutiva), Universidade de Lisboa, Faculdade de Ciências, 2016The present Ph.D. project constituted a first step in understanding mechanisms of reproductive isolation between two recently diverged sister species: the Lusitanian pine vole Microtus lusitanicus and the Mediterranean pine vole Microtus duodecimcostatus. Reproductive isolation is essential to speciation, and two types of isolation, preand post-mating, may prevent hybridization between two species. While premating barriers prevent copulation and promote conspecific reproduction, postmating barriers affect the success of heterospecific fertilization and hybrid viability, and potentiate its sterility. M. lusitanicus diverged from M. duodecimcostatus approximately 60,000 years ago, constituting one of the most recent speciation events among Microtus sp. voles. While M. lusitanicus inhabits the Northern region of the Iberian Peninsula, reaching the French Pyrenees, M. duodecimcostatus occupies Southern Iberia and part of the South of France. There is also a sympatry area of distribution, where both species occur, located in the centre of the Iberian Peninsula, covering parts of Portugal and Spain. Analyses on cytochrome b and microsatellites have uncovered a cytonuclear discordance over a large geographic area in Portugal, indicating a historical introgression of mitochondrial DNA from M. duodecimcostatus to M. lusitanicus. An incomplete reproductive isolation in nature is also suggested between both voles since two possible hybrids were detected in a sample size of nearly three hundred individuals. Moreover, behavioural isolation was hinted at, since there is a preference for conspecific over heterospecific odour cues. The gametic isolation barrier was proposed since heterospecific mating, in laboratory conditions, is less reproductively prolific than conspecific mating. This result suggests that fertilization between M. lusitanicus and M. duodecimcostatus may not always occur after copulation, probably due to incompatibilities in the sperm-oocyte heterospecific recognition. Considering these previous findings, the present Ph.D. project focused on M.lusitanicus and M. duodecimcostatus reproductive isolation, particularly on premating behavioural and post-mating gametic isolation barriers. It comprises five specific aims: 1) identify candidate genes related to odour cues communication; 2) analyse the expression of urinary proteins in both species; 3) infer if both species favour conspecific to heterospecific mating; 4) determine if both species present a pair bond, indicative of a monogamous mating system; and 5) evaluate the role of the sperm-binding protein zona pellucida 3, as a gametic isolation barrier. Four hypotheses were tested: 1) odour cues communication is an active behavioural reproductive barrier between M. lusitanicus and M. duodecimcostatus; 2) M. lusitanicus and M. duodecimcostatus prefer conspecific to heterospecific mating in the presence of potential mates of both species; 3) M. lusitanicus and M. duodecimcostatus are socially monogamous; and 4) the putative sperm-binding region of zona pellucida 3 is a gametic isolation barrier that impairs heterospecific mating between M. lusitanicus and M. duodecimcostatus. The results of the present Ph.D. project suggest that reproductive isolation between these sister species relies on multiple barriers and is still incomplete, enabling sporadic hybridization in nature. Overall, results also indicate that urinary proteins may play a role in species-specific discrimination; confirm social monogamy as the mating system of both voles, being a possible indirect behavioural isolation barrier at syntopy; reveal that individual behavioural variability may contribute to the behavioural isolation between M. lusitanicus and M. duodecimcostatus; and refute the putative sperm-binding region of ZP3 as a gametic barrier.FEDER (Fundo Europeu de Desenvolvimento Regional

Development of genomic resources for the prairie vole (Microtus ochrogaster): construction of a BAC library and vole-mouse comparative cytogenetic map

<p>Abstract</p> <p>Background</p> <p>The prairie vole (<it>Microtus ochrogaster</it>) is a premier animal model for understanding the genetic and neurological basis of social behaviors. Unlike other biomedical models, prairie voles display a rich repertoire of social behaviors including the formation of long-term pair bonds and biparental care. However, due to a lack of genomic resources for this species, studies have been limited to a handful of candidate genes. To provide a substrate for future development of genomic resources for this unique model organism, we report the construction and characterization of a bacterial artificial chromosome (BAC) library from a single male prairie vole and a prairie vole-mouse (<it>Mus musculus</it>) comparative cytogenetic map.</p> <p>Results</p> <p>We constructed a prairie vole BAC library (CHORI-232) consisting of 194,267 recombinant clones with an average insert size of 139 kb. Hybridization-based screening of the gridded library at 19 loci established that the library has an average depth of coverage of ~10×. To obtain a small-scale sampling of the prairie vole genome, we generated 3884 BAC end-sequences totaling ~2.8 Mb. One-third of these BAC-end sequences could be mapped to unique locations in the mouse genome, thereby anchoring 1003 prairie vole BAC clones to an orthologous position in the mouse genome. Fluorescence in situ hybridization (FISH) mapping of 62 prairie vole clones with BAC-end sequences mapping to orthologous positions in the mouse genome was used to develop a first-generation genome-wide prairie vole-mouse comparative cytogenetic map. While conserved synteny was observed between this pair of rodent genomes, rearrangements between the prairie vole and mouse genomes were detected, including a minimum of five inversions and 16 inter-chromosomal rearrangements.</p> <p>Conclusions</p> <p>The construction of the prairie vole BAC library and the vole-mouse comparative cytogenetic map represent the first genome-wide modern genomic resources developed for this species. The BAC library will support future genomic, genetic and molecular characterization of this genome and species, and the isolation of clones of high interest to the vole research community will allow for immediate characterization of the regulatory and coding sequences of genes known to play important roles in social behaviors. In addition, these resources provide an excellent platform for future higher resolution cytogenetic mapping and full genome sequencing.</p

Challenges to the Pair Bond: Neural and Hormonal Effects of Separation and Reunion in a Monogamous Primate

abstract: Social monogamy at its most basic is a group structure in which two adults form a unit and share a territory. However, many socially monogamous pairs display attachment relationships known as pair bonds, in which there is a mutual preference for the partner and distress upon separation. The neural and hormonal basis of this response to separation from the adult pair mate is under-studied. In this project, we examined this response in male titi monkeys (Callicebus cupreus), a socially monogamous New World primate. Males underwent a baseline scan, a short separation (48 h), a long separation (approximately 2 weeks), a reunion with the female pair mate and an encounter with a female stranger (with nine males completing all five conditions). Regional cerebral glucose metabolism was measured via positron emission tomography (PET) imaging using [18F]-fluorodeoxyglucose (FDG) co-registered with structural magnetic resonance imaging (MRI), and region of interest (ROI) analysis was carried out. In addition, plasma was collected and assayed for cortisol, oxytocin (OT), vasopressin (AVP), glucose and insulin concentrations. Cerebrospinal fluid (CSF) was collected and assayed for OT and AVP. We used generalized estimating equations (GEE) to examine significant changes from baseline. Short separations were characterized by decreases in FDG uptake, in comparison to baseline, in the lateral septum (LS), ventral pallidum (VP), paraventricular nucleus of the hypothalamus (PVN), periaqueductal gray (PAG), and cerebellum, as well as increases in CSF OT, and plasma cortisol and insulin. Long separations differed from baseline in reduced FDG uptake in the central amygdala (CeA), reduced whole brain FDG uptake, increased CSF OT and increased plasma insulin. The response on encounter with a stranger female depended on whether or not the male had previously reproduced with his pair mate, suggesting that transitions to fatherhood contribute to the neurobiology underlying response to a novel female. Reunion with the partner appeared to stimulate coordinated release of central and peripheral OT. The observed changes suggest the involvement of OT and AVP systems, as well as limbic and striatal areas, during separation and reunion from the pair mate.View the article as published at http://journal.frontiersin.org/article/10.3389/fnbeh.2016.00221/ful