QUANTIFYING NATURAL SELECTION ON BODY SIZE FROM FIELD DATA: WINTER MORTALITY IN MENIDIA MENIDIA

Ecology ◽  
2003 ◽  
Vol 84 (8) ◽  
pp. 2168-2177 ◽  
Author(s):  
Stephan B. Munch ◽  
Marc Mangel ◽  
David O. Conover
Keyword(s):  
Body Size ◽  
Natural Selection ◽  
Field Data ◽  
Winter Mortality ◽  
Menidia Menidia

Natural Selection on Beak and Body Size in the Song Sparrow

Evolution ◽  
1986 ◽  
Vol 40 (2) ◽  
pp. 221 ◽  
Author(s):  
Dolph Schluter ◽  
James N. M. Smith
Keyword(s):  
Body Size ◽  
Natural Selection ◽  
Song Sparrow

Evidence for divergent natural selection of a Lake Tanganyika cichlid inferred from repeated radiations in body size

2009 ◽  
Vol 18 (14) ◽  
pp. 3110-3119 ◽  
Author(s):  
T. TAKAHASHI ◽  
K. WATANABE ◽  
H. MUNEHARA ◽  
L. RÜBER ◽  
M. HORI
Keyword(s):  
Body Size ◽  
Natural Selection ◽  
Lake Tanganyika ◽  
Divergent Natural Selection ◽  
Selection Of

Darwinian fishery science: lessons from the Atlantic silverside (Menidia menidia)

2005 ◽  
Vol 62 (4) ◽  
pp. 730-737 ◽  
Author(s):  
David O Conover ◽  
Stephen A Arnott ◽  
Matthew R Walsh ◽  
Stephan B Munch
Keyword(s):  
Life History ◽  
Theory And Practice ◽  
Winter Mortality ◽  
Menidia Menidia ◽  
Adaptive Genetic Variation ◽  
Atlantic Silverside ◽  
Fishery Science ◽  
Evolutionary Changes ◽  
In The Wild ◽  
Contrary Evidence

The potential of fishing mortality to cause rapid evolutionary changes in life history has received relatively little attention. By focusing only on ecological responses, standard fisheries theory and practice implicitly assume either that genetic influences on life history in the wild are negligible or that natural selection and adaptation is a slow process that can be effectively ignored. Lack of contrary evidence has allowed these assumptions to persist. Drawing upon >25 years of research on the Atlantic silverside (Menidia menidia), we show that adaptive genetic variation in many traits is finely tuned to natural variation in climate. Much of this variation is caused by a gradient in size-selective winter mortality and involves two- to threefold changes in physiological traits that influence population productivity. Many other species are now known to display similar patterns. Harvest experiments show that these traits can evolve rapidly in response to size-selective fishing. Hence, the pool of genotypes that code for life history traits is a highly dynamic property of populations. We argue that the lessons from Menidia are applicable to many exploited species where similar observations would be difficult to obtain and advocate greater use of species models to address fundamental questions in fishery science.

scholarly journals Survival of Female Lesser Scaup: Effects of Body Size, Age, and Reproductive Effort

The Condor ◽  
2003 ◽  
Vol 105 (2) ◽  
pp. 336-347 ◽  
Author(s):  
Jay J. Rotella ◽  
Robert G. Clark ◽  
Alan D. Afton
Keyword(s):  
Body Size ◽  
Natural Selection ◽  
Female Body ◽  
Reproductive Effort ◽  
Cost Of Reproduction ◽  
Aythya Affinis ◽  
Female Body Size ◽  
Lesser Scaup ◽  
Adult Females ◽  
Breeding Propensity

AbstractIn birds, larger females generally have greater breeding propensity, reproductive investment, and success than do smaller females. However, optimal female body size also depends on how natural selection acts during other parts of the life cycle. Larger female Lesser Scaup (Aythya affinis) produce larger eggs than do smaller females, and ducklings from larger eggs survive better than those hatching from smaller eggs. Accordingly, we examined patterns of apparent annual survival for female scaup and tested whether natural selection on female body size primarily was stabilizing, a frequent assumption in studies of sexually dimorphic species in which males are the larger sex, or was directional, counteracting reproductive advantages of large size. We estimated survival using mark-recapture methods for individually marked females from two study sites in Canada (Erickson, Manitoba; St. Denis, Saskatchewan). Structurally larger (adults) and heavier (ducklings) females had lower survival than did smaller individuals in Manitoba; no relationship was detected in adults from Saskatchewan. Survival of adult females declined with indices of increasing reproductive effort at both sites; consequently, the cost of reproduction could explain age-related patterns of breeding propensity in scaup. Furthermore, if larger females are more likely to breed than are smaller females, then cost of reproduction also may help explain why survival was lower for larger females. Overall, we found that advantages of large body size of female scaup during breeding or as young ducklings apparently were counteracted by natural selection favoring lightweight juveniles and structurally smaller adult females through higher annual survival.Sobrevivencia de Aythya affinis: Efectos del Tamaño Corporal, Edad y Esfuerzo ReproductivoResumen. En las aves, las hembras de mayor tamaño generalmente presentan una mayor predisposición a la reproducción, mayor inversión reproductiva y mayor éxito que las hembras de menor tamaño. Sin embargo, el tamaño óptimo de la hembra también depende de cómo la selección natural opera durante otras etapas del ciclo de vida. Hembras de Aythya affinis más grandes producen huevos de mayor tamaño que hembras más pequeñas, y los polluelos provenientes de huevos más grandes sobreviven mejor que aquellos que eclosionan de huevos más pequeños. Consiguientemente, examinamos los patrones de sobrevivencia anual aparente para hembras de A. affinis y probamos si la selección natural sobre el tamaño del cuerpo de las hembras era principalmente estabilizadora (una suposición frecuente en estudios de especies sexualmente dimórficas en que los machos son el sexo mayor), o era direccional, contrarrestando las ventajas reproductivas de un tamaño mayor. Estimamos la sobrevivencia de hembras utilizando métodos de marcaje y recaptura en dos sitios de estudio (Erickson, Manitoba; St. Denis, Saskatchewan). Hembras estructuralmente más grandes (adultas) y más pesadas (polluelos) tuvieron una menor sobrevivencia que individuos más pequeños en Manitoba; no se detectó una relación entre adultos de Saskatchewan. En ambos sitios la sobrevivencia de hembras adultas decreció con los índices de incremento de esfuerzo reproductivo; consecuentemente el costo reproductivo podría explicar los patrones de predisposición reproductiva relacionados a la edad en A. affinis. Además, si las hembras de mayor tamaño presentan mayor probabilidad de reproducirse que las hembras pequeñas, entonces el costo reproductivo también podría ayudar a explicar porqué la sobrevivencia fue menor para hembras más grandes. En general encontramos que en las hembras de A. affinis las ventajas de un tamaño corporal grande durante la cría o como juveniles fueron aparentemente contrarestadas por la selección natural que favorece juveniles de peso liviano y hembras adultas estructuralmente más pequeñas a través de una mayor sobrevivencia anual.

The influence of geographic isolation on the skull of the green monkey ( Cercopithecus aethiops sabacus ) II. The cranial dimensions of the St Kitts and the African green monkey

1951 ◽  
Vol 138 (891) ◽  
pp. 204-213 ◽  
Keyword(s):  
Body Size ◽  
Natural Selection ◽  
African Green Monkey ◽  
Cercopithecus Aethiops ◽  
Geographic Isolation ◽  
General Body ◽  
Green Monkey ◽  
Parent Stock

Sixty-eight cranial dimensions of the St Kitts green monkey have been compared with the corresponding ones in the African green monkey. The skulls of the island monkeys are now bigger and less variable than those of the modern mainland descendants of its parent stock. The most meaningful changes have occurred in measurements of the breadth of the skull. No changes in the variability of meristic cranial characters have been found. The changes in the dimensions of the skull parallel those that have occurred in the teeth. It is possible that both result from the action of natural selection on a third reacting system, perhaps general body-size.

The size of dairy heifers

1960 ◽  
Vol 2 (2) ◽  
pp. 187-195 ◽  
Author(s):  
John Hodges ◽  
L. K. O'Connor ◽  
W. M. Clark
Keyword(s):  
Body Size ◽  
Field Data ◽  
Field Investigation ◽  
Covariance Analysis ◽  
Linear Effect ◽  
Dairy Heifers ◽  
The North ◽  
Chest Girth ◽  
The Mean ◽  
Effect Of Age

1. A field investigation to estimate the mean weight and chest girth of unserved Friesian, Ayrshire and Dairy Shorthorn heifers of between 3 and 24 months of age was carried out.2. Data from 1,620 Friesians, 725 Ayrshires and 455 Dairy Shorthorns in the North of England were obtained, with a mobile weighbridge and a. spring-loaded steel tape in the winter 1958–59.3. It was found that on average the Friesians were heavier and had a greater chest girth than the Ayrshires and Dairy Shorthorns, which did not differ significantly.4. These heifers were apparently reared on planes of nutrition which, judged by conventional feeding standards, may be described as ‘low’.5. After eliminating the linear effect of age by covariance analysis, highly significant differences between herds and between sires in weight and chest girth were found.6. The investigation demonstrated the feasibility and value of collecting field data on body size.

Body size and trophic divergence of two large sympatric elapid snakes (Notechis scutatus and Austrelaps superbus) (Serpentes:Elapidae) in Tasmania

2012 ◽  
Vol 60 (3) ◽  
pp. 159 ◽  
Author(s):  
S. Fearn ◽  
J. Dowde ◽  
D. F. Trembath
Keyword(s):  
Body Size ◽  
High Frequency ◽  
Field Data ◽  
Trophic Ecology ◽  
Competitive Exclusion ◽  
Head Size ◽  
Large Prey ◽  
Potential Prey ◽  
Island State ◽  
Species Being

Tiger snakes (Notechis scutatus) and lowland copperheads (Austrelaps superbus) are both large viviparous elapid snakes confined to the cooler, mesic regions of southern Australia. In spite of both species being common and widespread in the island state of Tasmania, no quantified studies on the trophic ecology of these two snakes from the main island has been published. During a two-year period we collected field data from 127 adult A. superbus and 74 adult N. scutatus from throughout eastern Tasmania. For both species, males were larger than females with respect to all measured parameters, including mass and head size. Reproduction in females was strongly seasonal and clutch size was not related to maternal body size. N. scutatus has a larger head than A. superbus and consequently ingests both small and large prey. N. scutatus in our study displayed the most catholic diet of any Australian elapid studied to date and consumed mammals (possum, bandicoot, antechinus, rats, mice), birds (fairy wrens), fish (eel, trout) and frogs. A. superbus shows a more specialist diet of large volumes of predominately ectothermic prey (frogs, lizards, snakes) even at maximal sizes and was more likely to contain ingested prey than specimens of N. scutatus. Distinctive rodent bite scars were common on N. scutatus but rare on A. superbus. The high frequency of rodent bite scars on N. scutatus further supports our findings of a primarily endothermic diet for mature specimens. We suggest that significant differences in head size, and hence diet, as well as a taxonomically diverse suite of potential prey in Tasmania allow both these large snakes to coexist in sympatry and avoid interspecific competitive exclusion.

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