Individual responses to population size structure: the role of size variation in controlling expression of a trophic polyphenism

Oecologia ◽  
1994 ◽  
Vol 100 (3) ◽  
pp. 279-285 ◽  
Author(s):  
T. J. Maret ◽  
J. P. Collins
Keyword(s):  
Population Size ◽  
Size Structure ◽  
Size Variation ◽  
Population Size Structure

Effect of Experimental Manipulation of Feeding Conditions on the Population Stucture of Larval Cod (Gadus morhua) and Herring (Clupea harengus).

1996 ◽  
Vol 47 (2) ◽  
pp. 291 ◽  
Author(s):  
AJ Geffen
Keyword(s):  
Standard Deviation ◽  
Population Size ◽  
Gadus Morhua ◽  
Size Structure ◽  
Size Variation ◽  
Experimental Manipulation ◽  
Rate Of Change ◽  
Clupea Harengus ◽  
Final Size ◽  
Population Size Structure

Cod and herring larvae were fed either rotifers or mixtures of rotifers, Artemia, and wild plankton to test the effects of feeding conditions on the development of population size structure. The population size structure at each sample date was characterized by the skewness, the standard deviation of mean length, the coefficient of variation of mean length and the Gini coefficient. The development of size structure through time was characterized by the spreading rate, which is the rate of change in the standard deviation of mean length over time. Larvae fed on a single, small-sized prey item (rotifers) grew slowly, and size variation increased slowly. Larvae fed on mixed prey species showed better growth; the population structure changed more rapidly, and often led to a skewed size distribution dominated by larger individuals. The presence of larger prey items resulted in disproportionate growth rates in the mixed-diet groups. The presence of these faster-growing individuals was the most important factor in determining the shape of the final size distributions and the development of the population size structure.

Population size structure and sex ratios in some woodlice (Crustacea: Oniscidae) from southern Africa

1994 ◽  
Vol 10 (2) ◽  
pp. 261-271 ◽  
Author(s):  
J. M. Dangerfield ◽  
S. R. Telford
Keyword(s):  
Population Size ◽  
Southern Africa ◽  
Life Histories ◽  
Mating Systems ◽  
Size Structure ◽  
Sex Ratios ◽  
Interspecific Variation ◽  
Sexual Competition ◽  
Population Size Structure ◽  
Adult Sex Ratio

ABSTRACTThe population size structure and adult sex ratio were recorded for four indigenous and one introduced species of terrestrial isopod from southern Africa. Interspecific variation was considerable with either discrete or continuous distributions indicative of the production of separate cohorts or continuous recruitment. Intraspecific variation was also considerable particularly in species such as Aphiloscia vilis which can be found in diverse habitats. Sex ratios were consistently female biased, a result consistent with observations made on temperate species. These observations, and a consideration of sexual dimorphism based on body mass, suggest that phenotypic plasticity may be an important tactic in the life histories of tropical woodlice and that in some populations the potential exists for strong sexual competition and complex mating systems.

Growth, reproduction, and population structure in four alpine lichens during 240 years of primary colonization

2004 ◽  
Vol 82 (9) ◽  
pp. 1356-1362 ◽  
Author(s):  
Geir Hestmark ◽  
Olav Skogesal ◽  
Øystein Skullerud
Keyword(s):  
Population Size ◽  
Life Histories ◽  
Size Structure ◽  
Growth Period ◽  
Maximum Size ◽  
Strongly Correlated ◽  
Interspecific Differences ◽  
Population Size Structure ◽  
The Relationship ◽  
Plant Life Histories

The increase in thallus diameter and apothecium production, and the population size structure of the saxicolous lichens Umbilicaria cylindrica (L.) Del., Umbilicaria hyperborea (Ach.) Hoffm., Umbilicaria proboscidea (L.) Schrad, and Umbilicaria torrefacta (Lightf.) Schrad, were measured in a chronosequence of 240 years in a glacier foreland in the alpine Jotunheimen National Park in Norway. All four species exhibited a pattern of fast growth in the early decades of their life history, followed by a rapid decrease in growth, slowly approaching a maximum body size. There were clear interspecific differences in initial estimated growth rate, growth period, and maximum size. In all species, apothecium production is strongly correlated with thallus size, but in U. hyperborea the relationship approximates an exponential function, while in the other species the trend is more linear. In U. proboscidea, the slowest to mature, a fairly high proportion of sterile individuals also occur in the higher size classes. There was no observed trade off between growth and reproduction. Quite the contrary: the species that grow faster also start to reproduce abundantly and early. The relatively slow growth and reproductive maturation of the species implies that a population of 40- to 50-year-old individual thalli is still a population consisting mainly of immigrants. The population size structure of all four species remains strongly skewed during the entire chronosequence, with a predominance of small thalli.Key words: plant life histories, lichen growth rates, size structure, Umbilicaria.

Efficacy of population size structure as a bioassessment tool in freshwaters

2013 ◽  
Vol 34 ◽  
pp. 571-579 ◽  
Author(s):  
Christina A. Murphy ◽  
Frederic Casals ◽  
Carolina Solà ◽  
Nuno Caiola ◽  
Adolf de Sostoa ◽  
...  
Keyword(s):  
Population Size ◽  
Size Structure ◽  
Population Size Structure
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