ALBERT

Description: The theory of evolution by natural selection can help explain why people care about other species. Building upon recent insights that morality evolves to secure fitness advantages of cooperation, we propose that conservation ethics (moral beliefs, attitudes, intuitions and norms regarding other species) could be adaptations that support cooperation between humans and non-humans. We present eco-evolutionary cost–benefit models of conservation behaviours as interspecific cooperation (altruism towards members of other species). We find that an evolutionary rule identical in structure to Hamilton's rule (which explains altruistic behaviour towards related conspecifics) can explain altruistic behaviour towards members of other species. Natural selection will favour traits for selectively altering the success of members of other species (e.g. conserving them) in ways that maximize inclusive fitness return benefits. Conservation behaviours and the ethics that evolve to reinforce them will be sensitive to local ecological and socio-cultural conditions, so will assume different contours in different places. Difficulties accurately assessing costs and benefits provided by other species, time required to adapt to ecological and socio-cultural change and barriers to collective action could explain the apparent contradiction between the widespread existence of conservation ethics and patterns of biodiversity decline globally.

Description: Madagascar's now-extinct radiation of large-bodied ratites, the elephant birds (Aepyornithidae), has been subject to little modern research compared to the island's mammalian megafauna and other Late Quaternary giant birds. The family's convoluted and conflicting taxonomic history has hindered accurate interpretation of morphological diversity and has restricted modern research into their evolutionary history, biogeography and ecology. We present a new quantitative analysis of patterns of morphological diversity of aepyornithid skeletal elements, including material from all major global collections of aepyornithid skeletal remains, and constituting the first taxonomic reassessment of the family for over 50 years. Linear morphometric data collected from appendicular limb elements, and including nearly all type specimens, were examined using multivariate cluster analysis and the Bayesian information criterion, and with estimation of missing data using multiple imputation and expectation maximization algorithms. These analyses recover three distinct skeletal morphotypes within the Aepyornithidae. Two of these morphotypes are associated with the type specimens of the existing genera Mullerornis and Aepyornis , and represent small-bodied and medium-bodied aepyornithids, respectively. Aepyornis contains two distinct morphometric subgroups, which are identified as the largely allopatric species A. hildebrandti and A. maximus. The third morphotype, which has not previously been recognized as a distinct genus, is described as the novel taxon Vorombe titan . Vorombe represents the largest-bodied aepyornithid and is the world's largest bird, with a mean body mass of almost 650 kg. This new taxonomic framework for the Aepyornithidae provides an important new baseline for future studies of avian evolution and the Quaternary ecology of Madagascar.

Description: Habitual reliance on tool use is a marked behavioural difference between wild robust (genus Sapajus ) and gracile (genus Cebus ) capuchin monkeys. Despite being well studied and having a rich repertoire of social and extractive foraging traditions, Cebus sp. rarely use tools and have never been observed using stone tools. By contrast, habitual tool use by Sapajus is widespread. We review theory and discuss factors which might explain these differences in patterns of tool use between Cebus and Sapajus . We then report the first case of habitual stone tool use in a gracile capuchin: a population of white-faced capuchins ( Cebus capucinus imitator ) in Coiba National Park, Panama who habitually rely on hammerstone and anvil tool use to access structurally protected food items in coastal areas including Terminalia catappa seeds, hermit crabs, marine snails, terrestrial crabs and other items. This behaviour has persisted on one island in Coiba National Park since at least 2004. From 1 year of camera trapping, we found that stone tool use is strongly male-biased. Of the 205 camera trap days where tool use was recorded, adult females were never observed to use stone tools, although they were frequently recorded at the sites and engaged in scrounging behaviour. Stone tool use occurs year-round in this population; over half of all identifiable individuals were observed participating. At the most active tool use site, 83.2% of days where capuchins were sighted corresponded with tool use. Capuchins inhabiting the Coiba archipelago are highly terrestrial, under decreased predation pressure and potentially experience resource limitation compared to mainland populations—three conditions considered important for the evolution of stone tool use. White-faced capuchin tool use in Coiba National Park thus offers unique opportunities to explore the ecological drivers and evolutionary underpinnings of stone tool use in a comparative within- and between-species context.

Description: A new Triassic neopterygian is described on the basis of a large three-dimensional neurocranium from the Rhaetian (Late Triassic) of the Kössen Formation (Schesaplana, Grisons, Switzerland). CT scanning reveals neurocranial features similar to Dapedium , suggesting that this new genus, Scopulipiscis saxciput gen. et sp. nov., was deep-bodied and potentially durophagous, although no associated dental material is known. An expanded phylogenetic analysis of actinopterygians resolves Dapediidae as a clade (inclusive of Tetragonolepis ), although fails to recover any characters supporting the monophyly of the genus Dapedium . Dapediids are resolved as stem holosteans, filling a conspicuous gap in early neopterygian relationships. Pycnodonts, previously suggested as either stem teleosts or the sister group to dapediids, are resolved as a clade on the neopterygian stem. Similarities between the new taxon described here and Dapedium provide insights into morphological disparity within early members of the group—suggesting that the ecological expansion of dapediids originated prior to the End-Triassic extinction—as well as contributing to a growing understanding of endocranial anatomy in Palaeozoic and Early Mesozoic actinopterygians.

Description: The Herefordshire (Silurian) Lagerstätte (approx. 430 Myr BP) has yielded, among many exceptionally preserved invertebrates, a wide range of new genera belonging to crown-group Panarthropoda. Here, we increase this panarthropod diversity with the lobopodian Thanahita distos , a new total-group panarthropod genus and species. This new lobopodian preserves at least nine paired, long, slender appendages, the anterior two in the head region and the posterior seven representing trunk lobopods. The body ends in a short post-appendicular extension. Some of the trunk lobopods bear two claws, others a single claw. The body is covered by paired, tuft-like papillae. Thanahita distos joins only seven other known three-dimensionally preserved lobopodian or onychophoran (velvet worm) fossil specimens and is the first lobopodian to be formally described from the Silurian. Phylogenetic analysis recovered it, together with all described Hallucigenia species, in a sister-clade to crown-group panarthropods. Its placement in a redefined Hallucigeniidae, an iconic Cambrian clade, indicates the survival of this clade to Silurian times.

Description: Here, we describe the odobenid Nanodobenus arandai gen. et sp. nov., based on a nearly complete left mandible from the mid to late Miocene Tortugas Formation in Baja California Sur. Nanodobenus is distinguished among odobenids by displaying a unique combination of plesiomorphic and derived characters, such as narrow mandibular symphysis, well-developed genial tuberosity, bilobed canine and p2 roots, bulbous post-canine teeth with the paraconid, protoconid and hypoconid, and smooth lingual cingula. Moreover, it is characterized by its small adult body length, which is estimated at about 1.65 m. Throughout the Miocene–Pliocene odobenids are characterized by an increase in body size, especially after the extinction of desmatophocids in the late Miocene. The small size of Nanodobenus departs from this trend, demonstrating that there was greater size disparity among odobenids in the mid–late Miocene than previously thought. It is hypothesized that Nanodobenus occupied a niche that was later on occupied by similar-sized otariids, such as Thalassoleon mexicanus, which occurs sympatrically with large odobenids in the overlying Almejas Formation.

Description: Collective motion is a fascinating and intensely studied manifestation of collective behaviour. Circular milling is an impressive example. It occurs in fishes, processionary caterpillars and army ants, among others. Its adaptive significance, however, is not yet well understood. Recently, we demonstrated experimentally circular milling in the marine plant–animal worm Symsagittifera roscoffensis . We hypothesized that its function is to gather the worms and facilitate the dense films they form on the beach to promote the photosynthesis of their symbiotic algae. Here, we report for the first time, to our knowledge, the occurrence of S. roscoffensis circular mills in nature and show that it is by no means rare. The size and behaviour of circular mills in their natural environment is compatible with our earlier experimental results. This makes S. roscoffensis a good study system for understanding the proximate and ultimate mechanisms of circular milling.

Description: As entomopathogens are detrimental to the development or even survival of insect societies, ant colonies should avoid digging into a substrate that is contaminated by fungal spores. Here, we test the hypotheses that Myrmica rubra ant workers (i) detect and avoid fungus-infected substrates and (ii) excavate nest patterns that minimize their exposure to entomopathogenic spores. Small groups of M. rubra workers were allowed to dig their nest in a two-dimensional sand plate of which one half of the substrate contained fungal spores of Metarhizium brunneum , while the other half was spore-free. We found that the overall digging dynamics of M. rubra nests was not altered by the presence of fungus spores. By contrast, the shape of the excavated areas markedly differed: control nests showed rather isotropic patterns, whereas nests that were partially dug into a fungus-contaminated substrate markedly deviated from a circular shape. This demonstrates that the sanitary risks associated with a digging substrate are key factors in nest morphogenesis. We also found that M. rubra colonies were able to discriminate between the two substrates (fungus-infected or not). Furthermore, some colonies unexpectedly showed a high consistency in excavating mainly the infected substrate. This seemingly suboptimal preference for a contaminated soil suggests that non-lethal doses of fungal spores could help ant colonies to trigger ‘immune priming’. The presence of fungi may also indicate favourable ecological conditions, such as humid and humus-rich soil, that ants use as a cue for selecting suitable nesting sites.

Description: In animal families, parents are expected to adapt to their offspring's traits, and offspring, in turn, are expected to adapt to the environment circumscribed by their parents. However, whether such coevolutionary trajectories differ between closely related species is poorly understood. Here, we employ interspecific cross-fostering in three species of burying beetles, Nicrophorus orbicollis , Nicrophorus pustulatus and Nicrophorus vespilloides , to test for divergent co-adaptation among species with different degrees of offspring dependency on parental care, and to test whether they are able to discriminate against interspecific parasites. We found that offspring survival was always higher when offspring were reared by conspecific rather than heterospecific parents. In the case of N. orbicollis raising N. pustulatus , none of the larvae survived. Overall, these results indicate that parent and offspring traits have diverged between species, and that the differential survival of conspecific and heterospecific larvae is because of improper matching of co-adapted traits, or, in the case of N. orbicollis with larval N. pustulatus , because of selection on parents to recognize and destroy interspecific brood parasites. We suggest that burying beetles experiencing a high risk of brood parasitism have evolved direct recognition mechanisms that enable them to selectively kill larvae of potential brood parasites.

Description: The vertebrate fossil record of the earliest Carboniferous is notoriously poorly sampled, obscuring a critical interval in vertebrate evolution and diversity. Recent studies of diversity across the Devonian–Carboniferous boundary have proposed a vertebrate mass extinction at the end-Devonian, and recent phylogenies suggest that the origin of the actinopterygian crown may have occurred in the earliest Carboniferous, as part of a broader recovery fauna. However, the data necessary to test this are limited. Here, we describe a partial actinopterygian skull, including diagnostic elements of the posterior braincase, from the Tournaisian Horton Bluff Formation of Blue Beach, Nova Scotia. The braincase surprisingly shows a confluence of characters common in Devonian taxa but absent in Mississippian forms, such as an open spiracular groove; lateral dorsal aortae that pass through open broadly separated, parallel grooves in the ventral otoccipital region, posterior to the articulation of the first infrapharyngobranchial and an intertemporal–supratemporal complex. Phylogenetic analysis places it deep within the actinopterygian stem, among Devonian moythomasiids and mimiids, suggesting more phylogenetically inclusive survivorship of stem group actinopterygians across the end-Devonian mass extinction. With a high lineage survivorship in tetrapods and lungfish across the Devonian–Carboniferous boundary and high vertebrate diversity at Tournaisian localities, this hints at a more gradual turnover between Devonian and Carboniferous vertebrate faunas.