Patterns of abundance, population size structure and microhabitat usage of Paracentrotus lividus (Echinodermata: Echinoidea) in SW Portugal and NW Italy

2013 ◽  
Vol 160 (5) ◽  
pp. 1135-1146 ◽  
Author(s):  
David Jacinto ◽  
Fabio Bulleri ◽  
Lisandro Benedetti-Cecchi ◽  
Teresa Cruz
Keyword(s):  
Population Size ◽  
Size Structure ◽  
Paracentrotus Lividus ◽  
Population Size Structure ◽  
Nw Italy ◽  
Sw Portugal

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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