Hasil untuk "Evolution"

T. Clutton‐Brock

Synthesizing studies of parental care in a wide variety of animals, this book is the first attempt to provide general answers to the following important questions: Why does the extent of parental care vary so widely between species? Why do only females care for eggs and young in some animals, only males in others, and both parents in a few? To what extent is parental care adjusted to variation in its benefits to offspring and its costs to parents? How do parents divide their resources between their sons and daughters? In this book separate chapters examine the evolution of variation in egg and neonate size, of viviparity and other forms of bearing, and of differences in the duration of incubation, gestation, and lactation. The book reviews theoretical and empirical predictions concerning the evolution of parental care and examines the extent to which these are supported by empirical evidence. The author examines the distribution of parental care among offspring, reviews the empirical evidence that parents invest to different extents in their sons and daughters, and discusses the degree to which parents manipulate the sex ratio of their progeny in relation to the availability of resources.

M. Gerlinger, A. Rowan, S. Horswell et al.

BACKGROUND Intratumor heterogeneity may foster tumor evolution and adaptation and hinder personalized-medicine strategies that depend on results from single tumor-biopsy samples. METHODS To examine intratumor heterogeneity, we performed exome sequencing, chromosome aberration analysis, and ploidy profiling on multiple spatially separated samples obtained from primary renal carcinomas and associated metastatic sites. We characterized the consequences of intratumor heterogeneity using immunohistochemical analysis, mutation functional analysis, and profiling of messenger RNA expression. RESULTS Phylogenetic reconstruction revealed branched evolutionary tumor growth, with 63 to 69% of all somatic mutations not detectable across every tumor region. Intratumor heterogeneity was observed for a mutation within an autoinhibitory domain of the mammalian target of rapamycin (mTOR) kinase, correlating with S6 and 4EBP phosphorylation in vivo and constitutive activation of mTOR kinase activity in vitro. Mutational intratumor heterogeneity was seen for multiple tumor-suppressor genes converging on loss of function; SETD2, PTEN, and KDM5C underwent multiple distinct and spatially separated inactivating mutations within a single tumor, suggesting convergent phenotypic evolution. Gene-expression signatures of good and poor prognosis were detected in different regions of the same tumor. Allelic composition and ploidy profiling analysis revealed extensive intratumor heterogeneity, with 26 of 30 tumor samples from four tumors harboring divergent allelic-imbalance profiles and with ploidy heterogeneity in two of four tumors. CONCLUSIONS Intratumor heterogeneity can lead to underestimation of the tumor genomics landscape portrayed from single tumor-biopsy samples and may present major challenges to personalized-medicine and biomarker development. Intratumor heterogeneity, associated with heterogeneous protein function, may foster tumor adaptation and therapeutic failure through Darwinian selection. (Funded by the Medical Research Council and others.).

D. Réale, S. Reader, D. Sol et al.

K. Engel, R. Nagel

A. Yin, T. Harrison

F. Abascal, R. Zardoya, D. Posada

M. West-Eberhard

S. Jeffery

S. Taylor, S. McLennan

Jerald B. Johnson, Kristian S. Omland

B. Jovanovic

S. Emlen, L. W. Oring

Henrique Teotónio, Michael R. Rose

J. McDonald, M. Kreitman

J. Avise

J. Travis, S. Stearns

M. Ablowitz, Peter A. Clarkson

R. Whittaker

E. Ostrom

I assume multiple types of players--“rational egoists,” as well as “conditional cooperators” and “willing punishers”--in models of nonmarket behavior. I use an indirect evolutionary approach to explain how multiple types of players could survive and flourish in social dilemma situations. Contextual variables that enhance knowledge about past behavior assist in explaining the origin of collective action. Among the important contextual variables are types of goods, types of groups, and rules that groups use to provide and allocate goods. Finally, I reexamine a series of design principles that were derived earlier from an examination of extensive case materials.

S. Wright