Infant care classification for 105 primate species, from the appendix to Sarah Hrdy’s treatise on infant care [4], [52].

<p>Hrdy’s classification <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083667#pone.0083667-Hrdy3" target="_blank">[52]</a> follows: <i>Exclusive maternal care</i>: mother is very possessive and is the only one to hold and carry her infant. <i>Maternal and paternal care</i>: mother allows male she is paired with to take and carry infant and he is eager to do so. In New World monkeys, infant may actually take the initiative in transferring to “father.” Typically, the mother’s mate is the main caretaker, and alloparents are rarely involved. <i>Shared care</i>: mother is tolerant and allows allomothers to take and carry her infant within 3 weeks of birth. <i>Shared care with suckling</i>: group members other than the mother care for infants, and if the allomother is lactating, she allows an infant other than her own to suckle. Allomaternal suckling may range from occasional and brief access to more sustained access, as in species where two mothers share a nest. <i>Shared care + prov</i>: provisioning ranges from minimal to extensive. <i>Shared care + milk + provisioning</i>: combinations of behaviors described above.</p

Delay-constrained achievable rate maximization in wireless relay networks with causal feedback

Motivated by delay-sensitive information transmission applications, we propose an expected achievable rate maximization scheme with a K-block delay constraint on data transmission using a three node cooperative relay network assuming a block fading channel model. Channel information is fed back to the transmitter only in a causal fashion, so that the optimal power allocation strategy is only based on the current and past channel gains.We consider the two simplest schemes for information transmission using a three node (a source, a relay and a destination) relay network, namely the amplify and forward (AF) and decode and forward (DF) protocols. We use a dynamic programming based methodology to solve the (K-block delay constrained) expected capacity maximization problem with a short term (over K blocks) sum power (total transmission power of the source and the relay) constraint. Furthermore, two simple power allocation schemes for high and low SNR situations are proposed. Extensive numerical results are presented for Rayleigh fading channels, including results demonstrating the accuracy of the high/low SNR approximation based power allocation schemes

Plot of the fitness differences between Coalition Males () and Non-coalition Males () as a function of the differences in the level of Extra-Pair Matings (EPMs) and childcare.

<p>For the left panel the level of EPMs for Coalition Males is set at . The right panel has the level of paternal care for Non-coalition Males set at . The solid line with its respective confidence intervals (dashed lines) were estimated through simulation by drawing 10,000 random parameter sets from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083667#pone-0083667-t001" target="_blank">Table 1</a>. Gray regions highlight when Coalition Males are favored, with the corresponding white region showing when Non-coalition Males are favored. The level of kin selection () and positive assortment between Cooperative Mothers and Coalition Males () is zero.</p

Description of parameters in the evolutionary model and the ranges used in the Monte Carlo simulations.

<p>The simulations drew values uniformly across these parameter ranges.</p

Model analysis illustrating the scope for cooperative mothers.

<p>The upper row describes a deterministic process of the evolutionary dynamics of the three female strategies: Independent Mother (IM), Opportunistic Mother (OM), and Cooperative Mother (CM). The gray region is when selection favors CM, white region is when OM is favored, and the thicker dark line is where the fitness of OMs and IMs are the same. Panels (a)–(c) assume parameter values , , , , , , and . However panel (a) assumes no kin selection () and panel (b) prescribes weak kin selection (), and panel (c) specifies strong kin selection (). The bottom row of panels describes the basin of attraction for Cooperative Mothers through stochastic simulation as a function of the repeated interaction parameter (panel (d)), level of kin selection (panel (e)), and the effect of alloparental care (panel (f)). The position of the unstable equilibrium between OM and CM females shown in the ternary plots above defines the basin of attraction. The dashed curves are 95% confidence bounds around the mean (solid line) computed by taking 1000 random uniform parameter values within the ranges reported in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083667#pone-0083667-t001" target="_blank">Table 1</a> for each value of , , and on the horizontal axis for panels (d)–(f), respectively.</p

Influences on population survival.

<p>(A) The percent of runs in which the population survived as a function of the initial cooperator frequency, for <i>β</i> = 100. (B) The effect of both high cooperator frequency and high genetic quality on population survival for high costs of childrearing compared with the baseline model. Initial conditions in the “high fitness” condition were a cooperator frequency of 90% and a mean genetic quality of 0.86, compared with 50% cooperators and mean genetic quality of 0.5 in the baseline condition.</p

An illustration of the individual and group structure of the model.

<p>There are a number of family groups, each of which contains a unique set of agents. Unmarried agents are colored, married agents are grey. Because children's lives are attached to their mothers' until they reach adulthood, children are not shown. Each agent is characterized by sex, age, marital status, cooperativity, and genetic quality.</p

Variability in the costs of childrearing.

<p>The difference in cooperator frequency at <i>t</i> = 10⁴ between noisy and noiseless environments, as calculated by the mean cooperator frequency without noise subtracted from the mean cooperator frequency with noise. For these runs, <i>γ</i> = 0.8 and <i>σ_ν</i> = 10.</p

Model dynamics under high costs of childrearing(<i>β</i> = 100).

<p>Model dynamics under high costs of childrearing(<i>β</i> = 100).</p

Model dynamics.

<p>The three rows reflect three different costs of childbirth. The left graphs reflect the average genetic quality in the population (in red) and the frequency of cooperators (in blue). The right graphs are the total population size. The dark lines are averages across 50 runs (or all runs in which the population did not go extinct), the shaded regions are standard deviations.</p