The maximum rate of mammal evolution

How fast can a mammal evolve from the size of a mouse to the size of an elephant? Achieving such a large transformation calls for major biological reorganization. Thus, the speed at which this occurs has important implications for extensive faunal changes, including adaptive radiations and recovery from mass extinctions. To quantify the pace of large-scale evolution we developed a metric, clade maximum rate, which represents the maximum evolutionary rate of a trait within a clade. We applied this metric to body mass evolution in mammals over the last 70 million years, during which multiple large evolutionary transitions occurred in oceans and on continents and islands. Our computations suggest that it took a minimum of 1.6, 5.1, and 10 million generations for terrestrial mammal mass to increase 100-, and 1,000-, and 5,000- fold, respectively. Values for whales were down to half the length (i.e., 1.1, 3, and 5 million generations), perhaps due to the reduced mechanical constraints of living in an aquatic environment. When differences in generation time are considered, we find an exponential increase in maximum mammal body mass during the 35 million years following the Cretaceous–Paleogene (K–Pg) extinction event. Our results also indicate a basic asymmetry in macroevolution: very large decreases (such as extreme insular dwarfism) can happen at more than 10 times the rate of increases. Our findings allow more rigorous comparisons of microevolutionary and macroevolutionary patterns and processes. Keywords: haldanes, biological time, scaling, pedomorphosis

Biała Góra: the forgotten colony in the Medieval Pomeranian-Prussian borderlands

Biała Góra 3 is a small settlement founded in the late twelfth or early thirteenth century AD in the disputed Christian borderlands of Northern Europe. The incorporation of Pomerania into the Polish state in the tenth century was followed by a process of colonisation across the lower Vistula valley, which then stalled before resuming in the thirteenth century under the Teutonic Order. Biała Góra 3 is unusual in falling between the two expansionist phases and provides detailed insight into the ethnicity and economy of this borderland community. Pottery and metalwork show strong links with both Pomeranian and German colonists, and caches of bricks and roof tiles indicate durable buildings of the kind associated with the monastic and military orders. Evidence for the presence of merchants suggests Biała Góra 3 was one of many outposts in the commercial network that shadowed the Crusades.

Harnessing microbiome and probiotic research in sub-Saharan Africa: recommendations from an African workshop

To augment capacity-building for microbiome and probiotic research in Africa, a workshop was held in Nairobi, Kenya, at which researchers discussed human, animal, insect, and agricultural microbiome and probiotics/prebiotics topics. Five recommendations were made to promote future basic and translational research that benefits Africans.

Survival at the frontier of Holy War: political expansion, crusading, commerce and the medieval colonizing settlement at Biała Gora, North Poland

Between the eleventh and thirteenth centuries AD, the Lower Vistula valley represented a permeable and shifting frontier between Pomerelia (eastern Pomerania), which had been incorporated into the Polish Christian state by the end of the tenth century, and the territories of western Prussian tribes, who had resisted attempts at Christianization. Pomeranian colonization eventually began to falter in the latter decades of the twelfth and early thirteenth centuries, most likely as a result of Prussian incursions, which saw the abandonment of sites across the borderland. Subsequently, the Teutonic Order and its allies led a protracted holy war against the Prussian tribes, which resulted in the conquest of the region and its incorporation into a theocratic state by the end of the thirteenth century. This was accompanied by a second wave of colonization, which resulted in the settlement pattern that is still visible in the landscape of north-central Poland today. However, not all colonies were destroyed or abandoned in between the two phases of colonization. The recently excavated site of Biała Góra, situated on the western side of the Forest of Sztum overlooking the River Nogat, represents a unique example of a transitional settlement that included both Pomeranian and Teutonic Order phases. The aim of this paper is to situate the site within its broader landscape context which can be characterized as a militarized frontier, where, from the later twelfth century and throughout much of the thirteenth century, political and economic expansion was combined with the ideology of Christian holy war and missionary activity. This paper considers how the colonists provisioned and sustained themselves in comparison to other sites within the region, and how Biała Góra may be tentatively linked to a documented but otherwise lost outpost in this volatile borderland.

The timing and causes of the Neolithic elm decline: new evidence from the Lower Thames Valley (London, UK)

Two new multi-proxy records of environmental change are provided from Horton Kirby Paper Mill and Old Seager Distillery in the Lower Thames Valley. Each site has evidence for a decline in elm woodland, which at Horton Kirby Paper Mill is recorded earlier than any other published record from the British Isles: sometime between 7320 and 7240 cal BP. Scolytus scolytus/S. multistriatus (the vectors for Dutch elm disease) are recorded after the decline in both sequences, adding to the number of sites with such evidence in the British Isles. Evidence of paludification and human activity are also recorded at the time of the elm decline reinforcing the multi-causal hypothesis. Integration of these results with 21 palaeoenvironmental records has produced a large number of well-dated, multiproxy records of the elm decline in this part of the UK. On the basis of this dataset, a classification system for categorising the relationships between the causal factors of the elm decline is proposed and recommended for future studies.

Effects of allometry, productivity and lifestyle on rates and limits of body size evolution

Body size affects nearly all aspects of organismal biology, so it is important to understand the constraints and dynamics of body size evolution. Despite empirical work on the macroevolution and macroecology of minimum and maximum size, there is little general quantitative theory on rates and limits of body size evolution. We present a general theory that integrates individual productivity, the lifestyle component of the slow–fast life-history continuum, and the allometric scaling of generation time to predict a clade's evolutionary rate and asymptotic maximum body size, and the shape of macroevolutionary trajectories during diversifying phases of size evolution. We evaluate this theory using data on the evolution of clade maximum body sizes in mammals during the Cenozoic. As predicted, clade evolutionary rates and asymptotic maximum sizes are larger in more productive clades (e.g. baleen whales), which represent the fast end of the slow–fast lifestyle continuum, and smaller in less productive clades (e.g. primates). The allometric scaling exponent for generation time fundamentally alters the shape of evolutionary trajectories, so allometric effects should be accounted for in models of phenotypic evolution and interpretations of macroevolutionary body size patterns. This work highlights the intimate interplay between the macroecological and macroevolutionary dynamics underlying the generation and maintenance of morphological diversity.

Bdellovibrio bacteriovorus HD100 guards against Pseudomonas tolaasii brown-blotch lesions on the surface of post-harvest Agaricus bisporus supermarket mushrooms

BACKGROUND: Pseudomonas tolaasii is a problematic pathogen of cultured mushrooms, forming dark brown 'blotches' on mushroom surfaces and causing spoilage during crop growth and post-harvest . Treating P. tolaasii infection is difficult, as other, commensal bacterial species such as Pseudomonas putida are necessary for mushroom growth, so treatments must be relatively specific. RESULTS: We have found that P. tolaasii is susceptible to predation in vitro by the δ-proteobacterium Bdellovibrio bacteriovorus. This effect also occurred in funga, where B. bacteriovorus was administered to post-harvest mushroom caps before and after administration of the P. tolaasii pathogen. A significant, visible improvement in blotch appearance, after incubation, was observed on administration of Bdellovibrio. A significant reduction in viable P. tolaasii cell numbers, recovered from the mushroom tissue, was detected. This was accompanied by a more marked reduction in blotch severity on Bdellovibrio administration. We found that there was in some cases an accompanying overgrowth of presumed-commensal, non-Pseudomonas bacteria on post-harvest mushroom caps after Bdellovibrio-treatment. These bacteria were identified (by 16SrRNA gene sequencing) as Enterobacter species, which were seemingly resistant to predation. We visualised predatory interactions occuring between B. bacteriovorus and P. tolaasii on the post-harvest mushroom cap surface by Scanning Electron Microscopy, seeing predatory invasion of P. tolaasii by B. bacteriovorus in funga. This anti-P. tolaasii effect worked well in post-harvest supermarket mushrooms, thus Bdellovibrio was not affected by any pre-treatment of mushrooms for commercial/consumer purposes. CONCLUSIONS: The soil-dwelling B. bacteriovorus HD100 preys upon and kills P. tolaasii, on mushroom surfaces, and could therefore be applied to prevent spoilage in post-harvest situations where mushrooms are stored and packaged for sale.

Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: the challenge ahead

Lifestyle factors are responsible for a considerable portion of cancer incidence worldwide, but credible estimates from the World Health Organization and the International Agency for Research on Cancer (IARC) suggest that the fraction of cancers attributable to toxic environmental exposures is between 7% and 19%. To explore the hypothesis that low-dose exposures to mixtures of chemicals in the environment may be combining to contribute to environmental carcinogenesis, we reviewed 11 hallmark phenotypes of cancer, multiple priority target sites for disruption in each area and prototypical chemical disruptors for all targets, this included dose-response characterizations, evidence of low-dose effects and cross-hallmark effects for all targets and chemicals. In total, 85 examples of chemicals were reviewed for actions on key pathways/mechanisms related to carcinogenesis. Only 15% (13/85) were found to have evidence of a dose-response threshold, whereas 59% (50/85) exerted low-dose effects. No dose-response information was found for the remaining 26% (22/85). Our analysis suggests that the cumulative effects of individual (non-carcinogenic) chemicals acting on different pathways, and a variety of related systems, organs, tissues and cells could plausibly conspire to produce carcinogenic synergies. Additional basic research on carcinogenesis and research focused on low-dose effects of chemical mixtures needs to be rigorously pursued before the merits of this hypothesis can be further advanced. However, the structure of the World Health Organization International Programme on Chemical Safety 'Mode of Action' framework should be revisited as it has inherent weaknesses that are not fully aligned with our current understanding of cancer biology.

Impact of US Brown Swiss genetics on milk quality from low-input herds in Switzerland: interactions with grazing intake and pasture type

This study investigated the effect of, and interactions between, contrasting crossbreed genetics (US Brown Swiss [BS] × Improved Braunvieh [BV] × Original Braunvieh [OB]) and feeding regimes (especially grazing intake and pasture type) on milk fatty acid (FA) profiles. Concentrations of total polyunsaturated FAs, total omega-3 FAs and trans palmitoleic, vaccenic, α-linolenic, eicosapentaenoic and docosapentaenoic acids were higher in cows with a low proportion of BS genetics. Highest concentrations of the nutritionally desirable FAs, trans palmitoleic, vaccenic and eicosapentaenoic acids were found for cows with a low proportion of BS genetics (0-24% and/or 25-49%) on high grazing intake (75-100% of dry matter intake) diets. Multivariate analysis indicated that the proportion of OB genetics is a positive driver for nutritionally desirable monounsaturated and polyunsaturated FAs while BS genetics proportion was positive driver for total and undesirable individual saturated FAs. Significant genetics × feeding regime interactions were also detected for a range of FAs.