School of Natural Science http://hdl.handle.net/2262/9 2013-06-19T09:04:28Z 2013-06-19T09:04:28Z COOPER, NATALIE RODRIGUEZ, JESUS PURVIS, ANDY http://hdl.handle.net/2262/64936 2012-09-10T11:42:30Z 2008-01-01T00:00:00Z

Title: A common tendency for phylogenetic overdispersion in mammalian assemblages Author: COOPER, NATALIE; RODRIGUEZ, JESUS; PURVIS, ANDY Abstract: Competition has long been proposed as an important force in structuring mammalian communities. Although early work recognised that competition has a phylogenetic dimension, only with recent increases in the availability of phylogenies have true phylogenetic investigations of mammalian community structure become possible. We test whether the phylogenetic structure of 142 assemblages from three mammalian clades (New World monkeys, North American ground squirrels and Australasian possums) shows the imprint of competition. The full set of assemblages display a highly significant tendency for members to be more distantly-related than expected by chance (phylogenetic overdispersion). The overdispersion is also significant within two of the clades (monkeys and squirrels) separately. This is the first demonstration of widespread overdispersion in mammal assemblages and implies an important role for either competition between close relatives where traits are conserved, habitat filtering where distant relatives share convergent traits, or both. Description: PUBLISHED

2008-01-01T00:00:00Z COOPER, NATALIE BIELBY, JON THOMAS, GAVIN H PURVIS, ANDY http://hdl.handle.net/2262/64935 2012-09-10T11:29:42Z 2008-01-01T00:00:00Z

Title: Macroecology and extinction risk correlates of frogs Author: COOPER, NATALIE; BIELBY, JON; THOMAS, GAVIN H; PURVIS, ANDY Abstract: Aim Our aim was to test whether extinction risk in frogs could be predicted from their body size, fecundity or geographic range size. Because small geographic range size is a correlate of extinction risk in many taxa, we also tested hypotheses about correlates of range size in frogs. Methods Using a large comparative dataset (n = 527 species) compiled from the literature we performed bivariate and multiple regressions through the origin of independent contrasts, to test proposed macroecological patterns and correlates of extinction risk in frogs. We also created minimum adequate models to predict snout-vent length, clutch size, geographic range size and IUCN Red List status in frogs. Parallel non-phylogenetic analyses were also conducted. We verified the results of the phylogenetic analyses using gridded data accounting for spatial autocorrelation. Results The most threatened frogs tend to have small geographic ranges although the relationship between range and extinction risk is not linear. In addition, tropical frogs with small clutches have the smallest ranges. Clutch size was strongly positively correlated with geographic range size (r2 = 0.22) and body size (r2 = 0.28). Main conclusions Our results suggest that body size and fecundity only affect extinction risk indirectly through their effect on geographic range size. Thus, although large frogs with small clutches tend to be endangered, there is no comparative evidence that this relationship is direct. If correct, this inference has consequences for conservation strategy: it would be inefficient to allocate conservation resources on the basis of low fecundity or large body size; instead it would be better to protect areas which contain many, small geographic range frog species. Description: PUBLISHED

2008-01-01T00:00:00Z COOPER, NATALIE PURVIS, ANDY http://hdl.handle.net/2262/64934 2012-09-10T11:08:33Z 2010-01-01T00:00:00Z

Title: Body size evolution in mammals: complexity in tempo and mode Author: COOPER, NATALIE; PURVIS, ANDY Abstract: Body size correlates with virtually every aspect of species’ biology, so understanding the tempo and mode of its evolution is of key importance in macroecology and macroevolution. Here we use body-mass data from 3473 of 4510 extant mammalian species and an almost complete species-level phylogeny to determine the best model of log(body-mass) evolution across all mammals, split taxonomically and spatially. An early-burst model fits better across all mammals than models based on either Brownian motion or an Ornstein-Uhlenbeck process, suggesting that mammals experienced a burst of morphological evolution relatively early in their history followed by slower change subsequently. We also use spatial models to investigate rates of body-mass evolution within ecoregions. These models show that around 50% of the variation in rate can be explained by just a few predictors. High estimated rates are associated with cold, low lying, species-poor, high energy, mainland ecoregions. We conclude that the evolution of mammalian body size has been influenced by a complex interplay among geography, climate and history. Description: PUBLISHED

2010-01-01T00:00:00Z COOPER, NATALIE BELMAKER, JONATHAN LEE, TIEN MING WILMAN, HAMISH http://hdl.handle.net/2262/64932 2012-09-10T10:56:31Z 2011-01-01T00:00:00Z

Title: Specialization and the road to academic success Author: COOPER, NATALIE; BELMAKER, JONATHAN; LEE, TIEN MING; WILMAN, HAMISH Abstract: The relative merits of focusing research on few areas of science versus generalizing across topics have important implications for how academics conduct science. Little is known, however, about how research breadth and academic success are related. Drawing on data from more than 4000 ecologists and evolutionary biologists worldwide, we show that highest academic success is achieved at intermediate levels of research breadth. This suggests that being a "jack of all trades" or an overly narrow specialist could both be detrimental to long term academic success. Description: PUBLISHED

2011-01-01T00:00:00Z COOPER, NATALIE KAMILAR, JASON M NUNN, CHARLES L http://hdl.handle.net/2262/64929 2012-09-10T10:00:07Z 2012-01-01T00:00:00Z

Title: Host longevity and parasite species richness in mammals. Author: COOPER, NATALIE; KAMILAR, JASON M; NUNN, CHARLES L Abstract: Hosts and parasites co-evolve, with each lineage exerting selective pressures on the other. Thus, parasites may influence host life-history characteristics, such as longevity, and simultaneously host life-history may influence parasite diversity. If parasite burden causes increased mortality, we expect a negative association between host longevity and parasite species richness. Alternatively, if long-lived species represent a more stable environment for parasite establishment, host longevity and parasite species richness may show a positive association. We tested these two opposing predictions in carnivores, primates and terrestrial ungulates using phylogenetic comparative methods and controlling for the potentially confounding effects of sampling effort and body mass. We also tested whether increased host longevity is associated with increased immunity, using white blood cell counts as a proxy for immune investment. Our analyses revealed weak relationships between parasite species richness and longevity. We found a significant negative relationship between longevity and parasite species richness for ungulates, but no significant associations in carnivores or primates. We also found no evidence for a relationship between immune investment and host longevity in any of our three groups. Our results suggest that greater parasite burden is linked to higher host mortality in ungulates. Thus, shorter-lived ungulates may be more vulnerable to disease outbreaks, which has implications for ungulate conservation, and may be applicable to other short-lived mammals. Description: PUBLISHED

2012-01-01T00:00:00Z COOPER, NATALIE http://hdl.handle.net/2262/64927 2012-09-10T09:52:01Z 2011-01-01T00:00:00Z

Title: Phylogenetic conservatism of environmental niches in mammals Author: COOPER, NATALIE Abstract: Phylogenetic niche conservatism is the pattern where close relatives occupy similar niches, whereas distant relatives are more dissimilar. We suggest that niche conservatism will vary across clades in relation to their characteristics. Specifically, we investigate how conservatism of environmental niches varies among mammals according to their latitude, range size, body size and specialization. We use the Brownian rate parameter, s2, to measure the rate of evolution in key variables related to the ecological niche and define the more conserved group as the one with the slower rate of evolution. We find that tropical, small-ranged and specialized mammals have more conserved thermal niches than temperate, large-ranged or generalized mammals. Partitioning niche conservatism into its spatial and phylogenetic components, we find that spatial effects on niche variables are generally greater than phylogenetic effects. This suggests that recent evolution and dispersal have more influence on species’ niches than more distant evolutionary events. These results have implications for our understanding of the role of niche conservatism in species richness patterns and for gauging the potential for species to adapt to global change. Description: PUBLISHED

2011-01-01T00:00:00Z MCNALLY, Luke BROWN, SAM P JACKSON, ANDREW LLOYD http://hdl.handle.net/2262/64204 2012-07-09T13:13:11Z 2012-01-01T00:00:00Z

Title: Cooperation and the evolution of intelligence Author: MCNALLY, Luke; BROWN, SAM P; JACKSON, ANDREW LLOYD Abstract: The high levels of intelligence seen in humans, other primates, certain cetaceans and birds remain a major puzzle for evolutionary biologists, anthropologists and psychologists. It has long been held that social interactions provide the selection pressures necessary for the evolution of advanced cognitive abilities (the ‘social intelligence hypothesis’), and in recent years decision-making in the context of cooperative social interactions has been conjectured to be of particular importance. Here we use an artificial neural network model to show that selection for efficient decision-making in cooperative dilemmas can give rise to selection pressures for greater cognitive abilities, and that intelligent strategies can themselves select for greater intelligence, leading to a Machiavellian arms race. Our results provide mechanistic support for the social intelligence hypothesis, highlight the potential importance of cooperative behaviour in the evolution of intelligence and may help us to explain the distribution of cooperation with intelligence across taxa. Description: PUBLISHED

2012-01-01T00:00:00Z JACKSON, Abaigeal Daly, Leslie Jackson, Andrew Marshall, Bruce Quinton, Hebe Fletcher, Godfrey Harrington, Mary Zhou, Shijun McKone, Edward Gallagher, Charles Foley, Linda Fitzpatrick, Patricia Kelleher, Cecily http://hdl.handle.net/2262/64103 2012-07-03T02:08:36Z 2011-07-21T23:00:00Z

Title: Validation and use of a parametric model for projecting cystic fibrosis survivorship beyond observed data: a birth cohort analysis Author: JACKSON, Abaigeal; Daly, Leslie; Jackson, Andrew; Marshall, Bruce; Quinton, Hebe; Fletcher, Godfrey; Harrington, Mary; Zhou, Shijun; McKone, Edward; Gallagher, Charles; Foley, Linda; Fitzpatrick, Patricia; Kelleher, Cecily Abstract: Background: The current lifetable approach to survival estimation is favoured by CF registries. Recognising the limitation of this approach, we examined the utility of a parametric survival model to project birth cohort survival estimates beyond the follow-up period, where short duration of follow-up meant median survival estimates were indeterminable. Methods: Parametric models were fitted to observed survivorship data from the US CF Foundation (CFF) Patient Registry 1980–1994 birth cohort. Model-predicted median survival was estimated. The best fitting model was applied to a Cystic Fibrosis Registry of Ireland dataset to allow an evaluation of the model's ability to estimate predicted median survival. This involved a comparison of birth cohort lifetable predicted and observed (Kaplan–Meier) median survival estimates. Results: A Weibull model with main effects of gender and birth cohort was developed using a US CFF dataset (n=13 115) for which median survival was not directly estimable. Birth cohort lifetable predicted median survival for male and female patients born between 1985 and 1994 and surviving their first birthday was 50.9 and 42.4 years respectively. To evaluate the accuracy of a Weibull model in predicting median survival, a model was developed for the 1980–1984 Cystic Fibrosis Registry of Ireland birth cohort (n=243), which had an observed (Kaplan–Meier) median survival of 27.7 years. Model-predicted median survival estimates were calculated using data censored at different follow-up periods. The estimates converged to the true value as length of follow-up increased. Conclusions: Accurate prognostic information that is clinically critical for care of patients affected by rare, life-limiting disorders can be provided by parametric survival models. Problems associated with short duration of follow-up for recent birth cohorts can be overcome using this approach, providing better opportunities to monitor survival and plan services locally. Description: PUBLISHED

2011-07-21T23:00:00Z CROWLEY, QUENTIN G http://hdl.handle.net/2262/64063 2012-06-27T15:49:30Z 2012-01-01T00:00:00Z

Title: Chemical abrasion applied to SHRIMP zircon geochronology: An example from the Variscan Karkonosze Granite (Sudetes, SW Poland) Author: CROWLEY, QUENTIN G Abstract: Thermal annealing followed by acid etching of zircon (chemical abrasion or CA) can be successfully utilised to minimize or eliminate the effects of major and cryptic Pb-loss for SIMS U–Pb zircon dating. The procedure is demonstrated by applying the U–Pb SIMS technique to both untreated and chemically abraded zircons from the Karkonosze Granite, Sudetes, SW Poland. Conventional U–Pb SIMS dating of untreated zircons yields an apparently coherent age population (n = 9) with a weighted mean 206Pb/238U age of 306 ± 4 Ma. Some untreated zircons display anomalously young 206Pb/238U ages (c. 225 and 238 Ma) and are likely to have suffered substantial Pb-loss. A sub-set of zircons from the same sample was chemically abraded. Physically, zircons treated in this manner display a range in the degree of etching and partial dissolution. Extreme examples developed a 3D network of sub-μm channels which follow high-U (dark CL) zones or linear defects, such as micro fractures or indistinct cleavage planes. U–Pb SIMS dating of treated zircons (n = 11) yields a mean 206Pb/238U age of 322 ± 3 Ma. Two analyses of treated zircons still display younger 206Pb/238U ages (c. 297 and 301 Ma) ascribed to the effects of Pb-loss. For the analysed sample, U–Pb ages determined from chemically abraded zircons are c. 5 % older than those from untreated zircons. This is attributed to effective removal of metamict domains susceptible to Pb-loss. The CA technique also removes micro-inclusions thus lowering common Pb and reducing matrix effects. A cryptic Pb-loss in untreated zircons is only recognised when compared with chemically abraded counterparts or ages determined using other isotope techniques. This clearly demonstrates the utility of CA to high-spatial resolution methods and stresses that Pb-loss is detectable at a range of scales, regardless of the analytical technique used. Description: PUBLISHED

2012-01-01T00:00:00Z HODKINSON, TREVOR ROLAND http://hdl.handle.net/2262/64038 2012-06-27T11:58:27Z 2011-01-01T00:00:00Z

Title: Marriage exchanges, seed exchanges, and the dynamics of manioc diversity Author: HODKINSON, TREVOR ROLAND Abstract: The conservation of crop genetic resources requires understanding the different variables-cultural, social, and economic-that impinge on crop diversity. In small-scale farming systems, seed exchanges represent a key mechanism in the dynamics of crop genetic diversity, and analyzing the rules that structure social networks of seed exchange between farmer communities can help decipher patterns of crop genetic diversity. Using a combination of ethnobotanical and molecular genetic approaches, we investigated the relationships between regional patterns of manioc genetic diversity in Gabon and local networks of seed exchange. Spatially explicit Bayesian clustering methods showed that geographical discontinuities of manioc genetic diversity mirror major ethnolinguistic boundaries, with a southern matrilineal domain characterized by high levels of varietal diversity and a northern patrilineal domain characterized by low varietal diversity. Borrowing concepts from anthropology-kinship, bridewealth, and filiation-we analyzed the relationships between marriage exchanges and seed exchange networks in patrilineal and matrilineal societies. We demonstrate that, by defining marriage prohibitions, kinship systems structure social networks of exchange between farmer communities and influence the movement of seeds in metapopulations, shaping crop diversity at local and regional levels. Description: PUBLISHED

2011-01-01T00:00:00Z