Edward O. Wilson’s research while affiliated with Harvard University and other places

Studying the historical biogeography and life history transitions from eusocial colony life to social parasitism contributes to our understanding of the evolutionary mechanisms generating biodiversity in eusocial insects. The ants in the genus Myrmecia are a well-suited system for testing evolutionary hypotheses about how their species diversity was assembled through time because the genus is endemic to Australia with the single exception of the species M. apicalis inhabiting the Pacific Island of New Caledonia, and because at least one social parasite species exists in the genus. However, the evolutionary mechanisms underlying the disjunct biogeographic distribution of M. apicalis and the life history transition(s) to social parasitism remain unexplored. To study the biogeographic origin of the isolated, oceanic species M. apicalis and to reveal the origin and evolution of social parasitism in the genus, we reconstructed a comprehensive phylogeny of the ant subfamily Myrmeciinae. We utilized Ultra Conserved Elements (UCEs) as molecular markers to generate a comprehensive molecular genetic dataset consisting of 2,287 loci per taxon on average for 66 out of the 93 known Myrmecia species as well as for the sister lineage Nothomyrmecia macrops and selected outgroups. Our time-calibrated phylogeny inferred that: (i) stem Myrmeciinae originated during the Paleocene ∼58 Ma ago; (ii) the current disjunct biogeographic distribution of M. apicalis was driven by long-distance dispersal from Australia to New Caledonia during the Miocene ∼14 Ma ago; (iii) the single social parasite species, M. inquilina, evolved directly from one of the two known host species, M. nigriceps, in sympatry via the intraspecific route of social parasite evolution; and (iv) 5 of the 9 previously established taxonomic species groups are non-monophyletic. We suggest minor changes to reconcile the molecular phylogenetic results with the taxonomic classification. Our study enhances our understanding of the evolution and biogeography of Australian bulldog ants, contributes to our knowledge about the evolution of social parasitism in ants, and provides a solid phylogenetic foundation for future inquiries into the biology, taxonomy, and classification of Myrmeciinae.

On West Indian islands, as elsewhere in the world, ants are a very important component of virtually every terrestrial ecosystem. Nonetheless, the ants of most West Indian islands have remained largely unknown and unstudied. Now several destructive exotic ant species are spreading through the region threatening native biodiversity. Here, we have compiled published and unpublished ant records and collected new specimens to document the diversity of ants on the island of Grenada. Our investigations increased the list of ant taxa known from the island of Grenada to 82 (65 New World and 17 Old World species). Of these, 71 species are represented among specimens we collected, while 11 are New World species known from Grenada based solely on earlier records. Some species recorded earlier, including at least nine not seen for more than 100 years, may now be extinct on Grenada. Grenada has more New World ant species than are known for Barbados (46), a neighboring island that has 34% more land area. Factors that may contribute to this difference include: 1) during low sea levels 15 kya, Grenada was part of a larger island about ten times Grenada’s current size, 2) Grenada is more mountainous than Barbados, and 3) Grenada has more remaining forest cover than Barbados (50.0% vs. 14.7%). Conversely, Grenada has fewer Old World ant species than are known for Barbados (24). Factors that may contribute to this difference include: 1) lower human population density, 2) lower levels of imported lumber products, and 3) lower tourism levels. Records for only four of the 17 Old World exotic ants found in Grenada date to before 1995. Major tramp ant species that are known from the West Indies, but have not yet been recorded from Grenada include Old World species, such as the pharaoh ant (Monomorium pharaonis), the African big-headed ant (Pheidole megacephala), and the difficult white-footed ant (Technomyrmex difficilis), as well as the red imported fire ant (Solenopsis invicta).

p>Our incomplete taxonomic knowledge impedes our attempts to protect biodiversity. A renaissance in the classification of species and their interactions is needed to guide conservation prioritization.</p

Significance Hamilton’s rule is a well-known concept in evolutionary biology. It is usually perceived as a statement that makes predictions about natural selection in situations where interactions occur between genetic relatives. Here, we examine what has been called the “exact and general” formulation of Hamilton’s rule. We show that in this formulation, which is widely endorsed by proponents of inclusive fitness theory, Hamilton’s rule does not make any prediction and cannot be tested empirically. This formulation of Hamilton’s rule is not a consequence of natural selection and not even a statement specifically about biology. We give simple and transparent expressions for the quantities of benefit, cost, and relatedness that appear in Hamilton’s rule, which reveal that these quantities depend on the data that are to be predicted.

The Caribbean region is considered a threatened biodiversity hotspot because of its high levels of biotic endemism and widespread habitat destruction. On Caribbean islands, as elsewhere in the world, ants are a critical component of virtually every terrestrial ecosystem. Nonetheless, the ants of most Caribbean islands remain poorly known. Here, we reviewed historical accounts, compiled published and unpublished ant records, and collected new specimens to document the diversity of ants on the Caribbean island of Barbados, including summary accounts for each species. We expected Barbados to have a relatively depauperate native ant fauna with few endemic species because of high isolation, young age, flat terrain, and high degree of habitat destruction. Furthermore, we expected to find many exotic ants, introduced throughout a long history of international commerce dating back to the 1600s. Our investigations increased the list of ant taxa known from Barbados to 69 (46 New World and 23 Old World). Of these, 62 are represented among specimens we collected, and seven are New World species only known from earlier records. We found that Barbados has fewer New World ant species and more Old World ant species than are known for Grenada and St. Vincent, two neighboring Caribbean islands of similar size. Most of the New World ant species in Barbados are continuously distributed from South American and Trinidad, through the Lesser Antilles and are probably native (i.e., predating human arrival). Some New World species in Barbados, however, may be exotics introduced through human commerce, as are all Old World ant species present. Six previously recorded New World species that we did not find may now be extinct in Barbados. These include Atta cephalotes lutea and Crematogaster brevidentata, the only two ant taxa thought to be endemic to Barbados, each collected just once >110 years ago.