Pollen‐Ovule Ratios And Hermaphrodite Sexual Allocation Strategies

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137413/1/evo00383.pd

Kin Selection and Its Discontents

Kin selection is a core aspect of social evolution theory, but a small number of critics have recently challenged it. Here I address these criticisms and show that kin selection remains an important explanation for much (though not all) social evolution. I show how many of the criticisms rest on historical idiosyncrasies of the way the field happened to develop, rather than on the real logic and evidence

Theory of genomic imprinting conflict in social insects

BACKGROUND: Genomic imprinting refers to the differential expression of genes inherited from the mother and father (matrigenes and patrigenes). The kinship theory of genomic imprinting treats parent-specific gene expression as products of within-genome conflict. Specifically, matrigenes and patrigenes will be in conflict over treatment of relatives to which they are differently related. Haplodiploid females have many such relatives, and social insects have many contexts in which they affect relatives, so haplodiploid social insects are prime candidates for tests of the kinship theory of imprinting. RESULTS: Matrigenic and patrigenic relatednesses are derived for individuals affected in a variety of contexts, including queen competition, sex ratio, worker laying of male eggs and policing, colony fission, and adoption of new queens. Numerous predictions emerge for what contexts should elicit imprinting, which individuals and tissues will show it, and the direction of imprinting effects. The predictions often vary for different genetic structures (varying queen and mate number) and often contrast with predictions for diploids. CONCLUSION: Because the contexts differ from the normal imprinting case, and because nothing is currently known about imprinting in social insects, these predictions can serve as a strong a priori test of the kinship theory of imprinting. If the predictions are correct, then social insects, which have long served as exemplars of cooperation between individuals, will also be shown to be extraordinary examples of competition within individual genomes

[Book review of] Adaptation in Metapopulations: How Interaction Changes Evolution, by Michael J. Wade.

Adaptation in Metapopulations: How Interaction Changes Evolution. By Michael J. Wade. Chicago (Illinois): University of Chicago Press . $120.00 (hardcover);$40.00 (paper). vii + 260 p.; ill.; index. ISBN: 978-0-226-12956-3 (hc); 978-0-226-12973-0 (pb); 978-0-226-12987-7 (eb). 2016

Privatization and Property in Biology

Organisms evolve to control, preserve, protect and invest in their own bodies. When they do likewise with external resources they privatize those resources and convert them into their own property. Property is a neglected topic in biology, although examples include territories, domiciles and nest structures, food caching, mate guarding, and the resources and partners in mutualisms. Property is important because it represents a solution to the tragedy of the commons; to the extent that an individual exerts long-term control of its property, it can use it prudently, and even invest in it. Resources most worth privatizing are often high in value. To be useful to their owner in the future, they are typically durable and defensible. This may explain why property is relatively rare in animals compared to humans. The lack of institutional property rights in animals also contributes to their rarity, although owner–intruder conventions may represent a simple form of property rights. Resources are often privatized by force or threat of force, but privatization can also be achieved by hiding, by constructing barriers, and by carrying or incorporating the property. Social organisms often have property for two reasons. First, the returns on savings and investments can accrue to relatives, including descendants. Second, social groups can divide tasks among members, so they can simultaneously guard property and forage, for example. Privatization enhances the likelihood that the benefits of cooperation will go to relatives, thus facilitating the evolution of cooperation as in Hamilton\u27s rule or kin selection. Mutualisms often involve exchange of property and privatization of relationships. Privatization ensures the stability of such cooperation. The major transitions in evolution, both fraternal and egalitarian, generally involve the formation of private clubs with something analogous to the nonrivalrous club goods of economics

Fine-scale spatial ecology drives kin selection relatedness among cooperating amoebae

Cooperation among microbes is important for traits as diverse as antibiotic resistance, pathogen virulence, and sporulation. The evolutionary stability of cooperation against “cheater” mutants depends critically on the extent to which microbes interact with genetically similar individuals. The causes of this genetic social structure in natural microbial systems, however, are unknown. Here, we show that social structure among cooperative Dictyostelium amoebae is driven by the population ecology of colonization, growth, and dispersal acting at spatial scales as small as fruiting bodies themselves. Despite the fact that amoebae disperse while grazing, all it takes to create substantial genetic clonality within multicellular fruiting bodies is a few millimeters distance between the cells colonizing a feeding site. Even adjacent fruiting bodies can consist of different genotypes. Soil populations of amoebae are sparse and patchily distributed at millimeter scales. The fine-scale spatial structure of cells and genotypes can thus account for the otherwise unexplained high genetic uniformity of spores in fruiting bodies from natural substrates. These results show how a full understanding of microbial cooperation requires understanding ecology and social structure at the small spatial scales microbes themselves experience

Fruiting bodies of the social amoeba \u3ci\u3eDictyostelium discoideum\u3c/i\u3e increase spore transport by Drosophila

Background: Many microbial phenotypes are the product of cooperative interactions among cells, but their putative fitness benefits are often not well understood. In the cellular slime mold Dictyostelium discoideum , unicellular amoebae aggregate when starved and form multicellular fruiting bodies in which stress-resistant spores are held aloft by dead stalk cells. Fruiting bodies are thought to be adaptations for dispersing spores to new feeding sites, but this has not been directly tested. Here we experimentally test whether fruiting bodies increase the rate at which spores are acquired by passing invertebrates. Results: Drosophila melanogaster accumulate spores on their surfaces more quickly when exposed to intact fruiting bodies than when exposed to fruiting bodies physically disrupted to dislodge spore masses from stalks. Flies also ingest and excrete spores that still express a red fluorescent protein marker. Conclusions: Multicellular fruiting bodies created by D. discoideum increase the likelihood that invertebrates acquire spores that can then be transported to new feeding sites. These results thus support the long-hypothesized dispersal benefits of altruism in a model system for microbial cooperation

DNA methylation is widespread across social Hymenoptera

SummaryGenomic imprinting is an epigenetic phenomenon by which the expression of a gene is influenced by the parent from which it is inherited. The evolutionary causes of imprinting are mysterious but it is likely to represent a form of within-genome conflict [1]. For instance, alleles inherited from the father and the mother will be in conflict over treatment of relatives to which they are differently related. In this context, natural selection may favor alleles with effects that differ depending on the allele's parental origin [1,2]. This ‘kinship theory of imprinting’ has been developed and tested largely in the context of parental provisioning of offspring [1,2]. Given their haplodiploid genetic system and interspecific variation in social traits, the Hymenoptera (ants, bees, and wasps) provide a large variety of novel contexts in which to examine this theory [2]. However, aside from evidence that imprinting determines sex in the parasitic wasp Nasonia vitripennis [3], and a QTL that appears to be paternally inherited in the honeybee [4], nothing is known about imprinting in this group of animals. Here we provide evidence that CpG methylation, a hallmark of imprinting, is ubiquitously present in social insects but the proportion of methylated sites varies substantially among species and developmental stages

Is there specificity in a defensive mutualism against soil versus lab nematodes, Dictyostelium discoideum farmers and their bacteria?

Background: The social amoeba Dictyostelium discoideum is a soil-dwelling microbe, which lives most of its life cycle in the vegetative stage as a predator of bacteria and as prey for nematodes. When bacteria are sparse, amoebae aggregate into a multicellular fruiting body. Some clones of D. discoideum have agriculture (Brock et al., 2011). They carry bacteria through the social stage, eat them prudently, and use some bacteria as defence against non-farming D. discoideum competitors. Caenorhabditis elegans preys on D. discoideum in the laboratory but does not encounter it in nature because C. elegans lives on rotten fruit. The nematode Oscheius tipulae is abundant in the soil. Questions: Do the defensive bacteria that farmers carry also protect farmers from nematodes? Is this protection specific to nematodes that reside with D. discoideum? Hypotheses: Many organisms evolve defensive mutualisms against predators. The natural habitat of D. discoideum is populated with nematodes. Therefore, we hypothesize that farming D. discoideum clones use non-food bacteria for protection from nematodes. We predicted higher fitness of farmers than non-farmers in the presence of nematodes. We also predicted to see this change of fitness only in the presence of the soil nematode, O. tipulae. Organisms: Amoeba Dictyostelium discoideum, nematodes Caenorhabditis elegans and Oscheius tipulae, bacteria Klebsiella pneumoniae and Burkholderia xenovorans. Methods: We compared spore production of D. discoideum farmers and non-farmers with and without nematodes. We also looked at nematode proliferation in the presence of farmers, non-farmers, K. pneumonia, and B. xenovorans. Results: Overall, farmer D. discoideum produced fewer spores than non-farmers. There was a decrease in the spore counts in the presence of nematodes for both farmers and non-farmers. There was a significant decrease in the percentage change in spore production for the farmers in the presence of soil nematodes but not laboratory nematodes. Nematode proliferation with the laboratory nematode and soil nematode did not vary in the presence of farmers, non-farmers, K. pneumoniae or B. xenovorans. Conclusion: The non-food bacteria that farmers carry do not provide defence against nematodes. In fact, it was a disadvantage for farmers to carry bacteria, since the soil nematode decreased spore production for farmers compared with non-farmers. However, the differences between the laboratory nematode and the soil nematode are marked enough to conclude that different species of nematodes respond differently to D. discoideum as a food source