The presence of a guard vicariously drives split sex ratios in a facultatively social bee.

Split sex ratios provide broad insights into how reproductive strategies evolve, and historically have special relevance to the evolution of eusociality. Yet almost no attention has been directed to situations where split sex ratios may potentially decrease the payoffs for worker-like behaviour, increasing selective thresholds for eusociality. We examined sex ratios in a facultatively social colletid bee, .

Unparalleled mitochondrial heteroplasmy and co-infection in the non-model bee, .

Mitochondrial heteroplasmy is the occurrence of more than one type of mitochondrial DNA within a single individual. Although generally reported to occur in a small subset of individuals within a species, there are some instances of widespread heteroplasmy across entire populations. is an Australian native bee species in the diverse and cosmopolitan bee family Colletidae.

Extreme reproductive skew at the dawn of sociality is consistent with inclusive fitness theory but problematic for routes to eusociality.

To understand the earliest stages of social evolution, we need to identify species that are undergoing the initial steps into sociality. is the only unambiguously known social species in the bee family Colletidae and represents an independent origin of sociality within the Apoidea. This allows us to investigate the selective factors promoting the transition from solitary to social nesting.

Does effective population size affect rates of molecular evolution: Mitochondrial data for host/parasite species pairs in bees suggests not.

Adaptive evolutionary theory argues that organisms with larger effective population size ( ) should have higher rates of adaptive evolution and therefore greater capacity to win evolutionary arm races. However, in some certain cases, species with much smaller may be able to survive besides their opponents for an extensive evolutionary time. Neutral theory predicts that accelerated rates of molecular evolution in organisms with exceedingly small are due to the effects of genetic drift and fixation of slightly deleterious mutations.

Holocene population expansion of a tropical bee coincides with early human colonization of Fiji rather than climate change.

There is substantial debate about the relative roles of climate change and human activities on biodiversity and species demographies over the Holocene. In some cases, these two factors can be resolved using fossil data, but for many taxa such data are not available. Inferring historical demographies of taxa has become common, but the methodologies are mostly recent and their shortcomings often unexplored.

Geographic patterns in colonial reproductive strategy in Myrmecina nipponica: Links between biogeography and a key polymorphism in ants.

The ability to express different phenotypes can help define species distributions by allowing access to, and exploitation of, new environments. Social insects employ two markedly different reproductive strategies with contrasting cost/benefit characteristics: independent colony foundation (ICF), which is associated with high dispersal range and high risk, and dependent colony foundation (DCF), characterized by low risk but low dispersal. The ant Myrmecina nipponica employs both of these strategies, with the frequency of each apparently varying between populations.

Climate change and invasive species: a physiological performance comparison of invasive and endemic bees in Fiji.

Anthropogenic climate change and invasive species are two of the greatest threats to biodiversity, affecting the survival, fitness and distribution of many species around the globe. Invasive species are often expected to have broad thermal tolerance, be highly plastic, or have high adaptive potential when faced with novel environments. Tropical island ectotherms are expected to be vulnerable to climate change as they often have narrow thermal tolerance and limited plasticity.

Molecular diversity and species delimitation in the family Gasteruptiidae (Hymenoptera: Evanioidea).

Gasteruptiidae Ashmead is an easily recognised family of wasps with ∼589 described species worldwide. Although well characterised by traditional taxonomy, multiple authors have commented on the extreme morphological uniformity of the group, making species-level identification difficult. This problem is enhanced by the lack of molecular data and molecular phylogenetic research for the group.

Radiation of tropical island bees and the role of phylogenetic niche conservatism as an important driver of biodiversity.

Island biogeography explores how biodiversity in island ecosystems arises and is maintained. The topographical complexity of islands can drive speciation by providing a diversity of niches that promote adaptive radiation and speciation. However, recent studies have argued that phylogenetic niche conservatism, combined with topographical complexity and climate change, could also promote speciation if populations are episodically fragmented into climate refugia that enable allopatric speciation.

Review of the bee genus Homalictus Cockerell (Hymenoptera: Halictidae) from Fiji with description of nine new species.

The genus Homalictus Cockerell has not been taxonomically reviewed in the Fijian archipelago for 40 years. Here we redescribe the four known species and describe nine new ones, bringing the number of endemic Homalictus in Fiji to 13 species. We provide identifications keys to all species.

Plio-Pleistocene diversification and biogeographic barriers in southern Australia reflected in the phylogeography of a widespread and common lizard species.

Palaeoclimatic events and biogeographical processes since the mid-Tertiary have played an important role in shaping the evolution and distribution of Australian fauna. However, their impacts on fauna in southern and arid zone regions of Australia are not well understood. Here we investigate the phylogeography of an Australian scincid lizard, Tiliqua rugosa, across southern Australia using mitochondrial DNA (mtDNA) and 11 nuclear DNA markers (nuDNA), including nine anonymous nuclear loci.

First record of Gasteruption Latreille (Hymenoptera: Evanioidea: Gasteruptiidae) from Fiji with the description of a new species.

A new Gasteruption Latreille species, G. tomanivi, is described from Viti Levu, Fiji. The new species is the first record of the genus for Fiji and can be distinguished from other Oceanian Gasteruption species by the length of the mesosoma and the large malar space compared with the length of the pedicel.

Group living in squamate reptiles: a review of evidence for stable aggregations.

How sociality evolves and is maintained remains a key question in evolutionary biology. Most studies to date have focused on insects, birds, and mammals but data from a wider range of taxonomic groups are essential to identify general patterns and processes. The extent of social behaviour among squamate reptiles is under-appreciated, yet they are a promising group for further studies.

Parallel responses of bees to Pleistocene climate change in three isolated archipelagos of the southwestern Pacific.

The impacts of glacial cycles on the geographical distribution and size of populations have been explored for numerous terrestrial and marine taxa. However, most studies have focused on high latitudes, with only a few focused on the response of biota to the last glacial maximum (LGM) in equatorial regions. Here, we examine how population sizes of key bee fauna in the southwest Pacific archipelagos of Fiji, Vanuatu and Samoa have fluctuated over the Quaternary.

Recent introduction of an allodapine bee into Fiji: A new model system for understanding biological invasions by pollinators.

Morphology-based studies have suggested a very depauperate bee fauna for islands in the South West Pacific, and recent genetic studies since have indicated an even smaller endemic fauna with many bee species in this region resulting from human-aided dispersal. These introduced species have the potential to both disrupt native pollinator suites as well as augment crop pollination, but for most species the timings of introduction are unknown. We examined the distribution and nesting biology of the long-tongued bee Braunsapis puangensis that was first recorded from Fiji in 2007.

First evidence for a massive extinction event affecting bees close to the K-T boundary.

Bees and eudicot plants both arose in the mid-late Cretaceous, and their co-evolutionary relationships have often been assumed as an important element in the rise of flowering plants. Given the near-complete dependence of bees on eudicots we would expect that major extinction events affecting the latter would have also impacted bees. However, given the very patchy distribution of bees in the fossil record, identifying any such extinctions using fossils is very problematic.

Diversification of Fijian halictine bees: insights into a recent island radiation.

Although bees form a key pollinator suite for flowering plants, very few studies have examined the evolutionary radiation of non-domesticated bees over human time-scales. This is surprising given the importance of bees for crop pollination and the effect of humans in transforming ecosystems via agriculture. In the Pacific, where the bee fauna appears depauperate, their importance as pollinators is not clear, particularly in Fiji where species diversity is even lower than neighbouring archipelagos.

Rapid diversification in Australia and two dispersals out of Australia in the globally distributed bee genus, Hylaeus (Colletidae: Hylaeinae).

Hylaeus is the only globally distributed colletid bee genus, with subgeneric and species-level diversity highest in Australia. We used one mitochondrial and two nuclear genes to reconstruct a phylogeny using Bayesian analyses of this genus based on species from Australia, Asia, Africa, Europe, Hawai'i, the New World and New Zealand. Our results concord with a ca.

A mid-cretaceous origin of sociality in xylocopine bees with only two origins of true worker castes indicates severe barriers to eusociality.

The origin of sterile worker castes, resulting in eusociality, represents one of the major evolutionary transitions in the history of life. Understanding how eusociality has evolved is therefore an important issue for understanding life on earth. Here we show that in the large bee subfamily Xylocopinae, a simple form of sociality was present in the ancestral lineage and there have been at least four reversions to purely solitary nesting.

Inclusive fitness theory and eusociality.

Arising from M. A. Nowak, C.

The evolution of eusociality in allodapine bees: workers began by waiting.

Understanding how sterile worker castes in social insects first evolved is one of the supreme puzzles in social evolution. Here, we show that in the bee tribe Allodapini, the earliest societies did not entail a foraging worker caste, but instead comprised females sharing a nest with supersedure of dominance. Subordinates delayed foraging until they became reproductively active, whereupon they provided food for their own brood as well as for those of previously dominant females.

Molecular phylogeny of the small carpenter bees (Hymenoptera: Apidae: Ceratinini) indicates early and rapid global dispersal.

The small carpenter bees (tribe Ceratinini, family Apidae) are recorded from all continents except Antarctica. The Ceratinini have a near-global distribution which contrasts strongly with their sister tribe, the Allodapini which has a largely southern Old World distribution. The Ceratinini therefore provides an excellent group to understand the factors that help determine the biogeography and radiation of the bees.

Social complexity in bees is not sufficient to explain lack of reversions to solitary living over long time scales.

Background: The major lineages of eusocial insects, the ants, termites, stingless bees, honeybees and vespid wasps, all have ancient origins (> or = 65 mya) with no reversions to solitary behaviour. This has prompted the notion of a 'point of no return' whereby the evolutionary elaboration and integration of behavioural, genetic and morphological traits over a very long period of time leads to a situation where reversion to solitary living is no longer an evolutionary option.

Results: We show that in another group of social insects, the allodapine bees, there was a single origin of sociality > 40 mya.

Evolution of sociality by natural selection on variances in reproductive fitness: evidence from a social bee.

Background: The Central Limit Theorem (CLT) is a statistical principle that states that as the number of repeated samples from any population increase, the variance among sample means will decrease and means will become more normally distributed. It has been conjectured that the CLT has the potential to provide benefits for group living in some animals via greater predictability in food acquisition, if the number of foraging bouts increases with group size. The potential existence of benefits for group living derived from a purely statistical principle is highly intriguing and it has implications for the origins of sociality.

Origins of social parasitism: the importance of divergence ages in phylogenetic studies.

Phylogenetic studies on insect social parasites have found very close host-parasite relationships, and these have often been interpreted as providing evidence for sympatric speciation. However, such phylogenetic inferences are problematic because events occurring after the origin of parasitism, such as extinction, host switching and subsequent speciation, or an incomplete sampling of taxa, could all confound the interpretation of phylogenetic relationships. Using a tribe of bees where social parasitism has repeatedly evolved over a wide time-scale, we show the problems associated with phylogenetic inference of sympatric speciation.