Dental functional morphology predicts the scaling of chewing rate in mammals

How food intake and mastication scale to satisfy the metabolic needs of mammals has been the subject of considerable scientific debate. Existing theory suggests that the negative allometric scaling of metabolic rate with body mass is compensated by a matching allometric scaling of the chewing rate. Why empirical studies have found that the scaling coefficients of the chewing rate seem to be systematically smaller than expected from theory remains unknown. Here we explain this imparity by decoupling the functional surface area of teeth from overall surface area. The functional surface area is relatively reduced in forms emphasizing linear edges (e.g., lophodont) compared with forms lacking linear structures (e.g., bunodont). In forms with reduced relative functional surface, the deficit in food processed per chew appears to be compensated for by increased chewing rate, such that the metabolic requirements are met. This compensation accounts for the apparent difference between theoretically predicted and observed scaling of chewing rates. We suggest that this reflects adaptive functional evolution to plant foods with different fracture properties and extend the theory to incorporate differences in functional morphology. (C) 2017 Elsevier Ltd. All rights reserved.Peer reviewe

Växthusgasutsläpp i västra Nyland – Kartläggning över år 2007

I västra Nyland genomfördes en kartlägging av växthusgasutsläpp för år 2007. I kartläggningen utreddes de mängder växthusgasutsläpp som uppstod i de åtta kommuner som är med i regioncenterprogrammet AKO Västra Nyland: Hangö, Ingå, Karislojo, Högfors, Lojo, Nummi–Pusula, Raseborg och Sjundeå. Utsläppskalkylerna utfördes under år 2009. I utsläppskalkylerna användes en växthusgas– och energibalansmodell för kommunnivå, utvecklad av Finlands miljöcentral. De kartlagda utsläppssektorerna var energin i dess olika former, industrins processer, lantbruket och avfallshanteringen. Inom dessa sektorer fastställdes utsläppen av koldioxid, metan och kväveoxidul. Den sammanlagda utsläppsnivån av växthusgaser var 3510 tusen ton koldioxi-dekvivalenter. Av dessa utsläpp uppstod huvudparten inom industrin och energiproduktionen (ca 70 %). Trafikens andel av utsläppen var cirka 10 % och utsläppen från fjärrvärme och byggnadernas separata uppvärmning i en klass om ungefär nio procent. Lantbrukets och avfallshanteringens andel av det totala utsläppet förblev rätt liten. Mellan kommunerna var variationen i utsläppsnivåer mycket stor, för i området finns både högt industrialiserade orter och kommuner nästan helt utan industri eller energiproduktion. Totalutsläppen varierade mellan 9 och 1283 tusen ton CO2–ekvivalenter. De högsta utsläppsnivåerna hade Hangö, Ingå och Lojo, som alla har stora industri– eller energiproduktionsanläggningar. Då utsläppen sattes i relation till kommunernas invånarantal, steg Hangö och Ingå till en nivå högt över de övriga, för i dessa kommuner finns anläggningar som producerar rikligt med utsläpp men få invånare. Utsläppen i förhållande till invånarantal var i hela det kartlagda området klart högre än medelvärdet för hela Finland: utsläppen av växthusgaser i hela Finland är ca 15 koldioxidekvivalentton per invånare, medan de i västra Nyland uppgick till nivån 34 t/inv. Resultaten från utsläppskartläggningen illustrerar utsläppsnivån i de västnyländska kommunerna år 2007. Resultaten kan utnyttjas vid planeringen av klimatstrategier och minskning av utsläppen i de kartlagda kommunerna. Även utsläppsnivåns utveckling kan i fortsättningen uppföljas genom att förnya kartläggningen vissa år inom samma område med samma metoder

Relative abundances and palaeoecology of four suid genera in the Turkana Basin, Kenya, during the late Miocene to Pleistocene

Most suids (Mammalia: Suidae, pigs) worldwide are omnivores living in closed environments, but the African warthog (Phacochoerus) has special adaptations for grazing in open environments. Similar specializations have been recorded from Plio-Pleistocene African suids. Four genera, Nyanzachoerus, Notochoerus, Kolpochoerus, and Metridiochoerus, have been discovered in late Miocene to middle Pleistocene locations around the Turkana Basin. We analyse the relative abundances of these four suid genera compared to other mammals, from approximately 8-0.7 Ma. The dataset includes most of the mammal specimens collected from locations around the Kenyan side of the Turkana Basin. Species of genus Nyanzachoerus were dominant before 4 Ma, but their relative abundance decreases through time thereafter. At the same time, Notochoerus increases in relative abundance, followed by Kolpochoerus, and finally Metridiochoerus. Their peak relative abundances do not overlap: Notochoerus peaks at 3.44-2.53 Ma, Kolpochoerus at 2.53-1.87 Ma, and Metridiochoerus at 1.38-0.7 Ma. We interpret the palaeoecology of these suids based on their relative abundances over time and on published isotope and pollen data. We find that Nyanzachoerus was replaced by its abrasive-diet-specialized successor Notochoerus, possibly in response to a rapid decrease in forest cover. Notochoerus adapted at first to the expanding wood- and grasslands, and then to more arid shrublands. After a period of severe aridity around 2.7-2.5 Ma, more variable environments allowed Kolpochoerus and Metridiochoerus to disperse, while Notochoerus disappeared, perhaps having lost its competitive edge. Further changes in the environment encouraged the expansion of grasslands over shrublands, favouring Metridiochoerus. Kolpochoerus persisted in the more closed environments near water sources.Peer reviewe

Small mammal tooth enamel carbon isotope record of C4 grasses in late Neogene China

Peer reviewe

Preliminary magnetostratigraphic results from the late Miocene Maragheh Formation, NW Iran

Maragheh in northwestern of Iran is a world famous Miocene fossil-bearing area. The area has yielded classical late Miocene Turolian age fauna that has been collected and studied sporadically over the last 150 years. However, the precise correlation of these sediments to the Global Time Scale (GTS) has remained ambiguous. To address this, 115 levels along an approximately 27-m-thick interval were collected from the middle Maragheh Formation at Dareh Gorg (Gort Daresi) section. Characteristic remanent magnetization directions obtained by alternating field demagnetization produce a polarity pattern that is supported by thermal demagnetization on a set of sister specimens. Three polarity intervals were recognised, the middle part of the section at around 15-21 m showing reversed polarity, bounded by normal polarities above and below. Based on the palaeontological constraints and recent K-Ar age determinations from the Maragheh Fm, three correlations to the geomagnetic polarity time scale appear likely. According to these correlations, recently discovered hominoid locality is correlated to C3Br.1n, C4n.1n, or to C4n.2n. For a unique correlation, however, additional palaeomagnetic data is required from the upper and lower parts of the section.Peer reviewe

Herbivore teeth predict climatic limits in Kenyan ecosystems

A major focus in evolutionary biology is to understand how the evolution of organisms relates to changes in their physical environment. In the terrestrial realm, the interrelationships among climate, vegetation, and herbivores lie at the heart of this question. Here we introduce and test a scoring scheme for functional traits present on the worn surfaces of large mammalian herbivore teeth to capture their relationship to environmental conditions. We modeled local precipitation, temperature, primary productivity, and vegetation index as functions of dental traits of large mammal species in 13 national parks in Kenya over the past 60 y. We found that these dental traits can accurately estimate local climate and environment, even at small spatial scales within areas of relatively uniform climate (within two ecoregions), and that they predict limiting conditions better than average conditions. These findings demonstrate that the evolution of key functional properties of organisms may be more reflective of demands during recurring adverse episodes than under average conditions or during isolated severe events.Peer reviewe

Preliminary magnetostratigraphic results from the late Miocene Maragheh Formation, NW Iran

Maragheh in northwestern of Iran is a world famous Miocene fossil-bearing area. The area has yielded classical late Miocene Turolian age fauna that has been collected and studied sporadically over the last 150 years. However, the precise correlation of these sediments to the Global Time Scale (GTS) has remained ambiguous. To address this, 115 levels along an approximately 27-m-thick interval were collected from the middle Maragheh Formation at Dareh Gorg (Gort Daresi) section. Characteristic remanent magnetization directions obtained by alternating field demagnetization produce a polarity pattern that is supported by thermal demagnetization on a set of sister specimens. Three polarity intervals were recognised, the middle part of the section at around 15-21 m showing reversed polarity, bounded by normal polarities above and below. Based on the palaeontological constraints and recent K-Ar age determinations from the Maragheh Fm, three correlations to the geomagnetic polarity time scale appear likely. According to these correlations, recently discovered hominoid locality is correlated to C3Br.1n, C4n.1n, or to C4n.2n. For a unique correlation, however, additional palaeomagnetic data is required from the upper and lower parts of the section.Peer reviewe

Evidence of strong stabilizing effects on the evolution of boreoeutherian (Mammalia) dental proportions.

The dentition is an extremely important organ in mammals with variation in timing and sequence of eruption, crown morphology, and tooth size enabling a range of behavioral, dietary, and functional adaptations across the class. Within this suite of variable mammalian dental phenotypes, relative sizes of teeth reflect variation in the underlying genetic and developmental mechanisms. Two ratios of postcanine tooth lengths capture the relative size of premolars to molars (premolar-molar module, PMM), and among the three molars (molar module component, MMC), and are known to be heritable, independent of body size, and to vary significantly across primates. Here, we explore how these dental traits vary across mammals more broadly, focusing on terrestrial taxa in the clade of Boreoeutheria (Euarchontoglires and Laurasiatheria). We measured the postcanine teeth of N = 1,523 boreoeutherian mammals spanning six orders, 14 families, 36 genera, and 49 species to test hypotheses about associations between dental proportions and phylogenetic relatedness, diet, and life history in mammals. Boreoeutherian postcanine dental proportions sampled in this study carry conserved phylogenetic signal and are not associated with variation in diet. The incorporation of paleontological data provides further evidence that dental proportions may be slower to change than is dietary specialization. These results have implications for our understanding of dental variation and dietary adaptation in mammals