Sexual size dimorphism, sex ratio and the relationship between seasonality and water quality in four species of Gordiida (Nematomorpha) from Catamarca, Argentina

2010 ◽  
Vol 85 (3) ◽  
pp. 319-324 ◽  
Author(s):  
L. Salas ◽  
C. De Villalobos ◽  
F. Zanca
Keyword(s):  
Water Quality ◽  
Sex Ratio ◽  
Water Temperature ◽  
Flow Rate ◽  
Sexual Size Dimorphism ◽  
Free Living ◽  
Size Dimorphism ◽  
Autumn And Winter ◽  
The Relationship

AbstractA total of 687 adult nematomorphs of four species of Gordiida:Chordodes brasiliensis(393 specimens),Noteochorododes cymatium(47 specimens),N. talensis(162 specimens) andPseudochordodes dugesi(85 specimens) were collected during a period of 1 year from El Simbolar stream, Argentina. Free-living worms were abundant during autumn and spring, but their number decreased during winter and summer. Males were shorter and significantly more abundant than females. The presence ofN. cymatium,N. talensisandP. dugesiwas correlated with water temperature and these species were most abundant in winter and spring. The presence ofC. brasiliensiswas correlated with flow rate and pH; this species was more abundant in autumn and winter. These four species are sympatric.

Population structure and dynamics of the freshwater shrimp Atyaephyra desmarestii (Millet, 1831) in the lower River Minho (NW Portugal)

Crustaceana ◽  
2015 ◽  
Vol 88 (6) ◽  
pp. 657-673 ◽  
Author(s):  
Maria L. Fidalgo ◽  
Paulo Santos ◽  
Cláudia Ferreira ◽  
Andreia Silva
Keyword(s):  
Water Quality ◽  
Reproductive Period ◽  
Specific Knowledge ◽  
Nw Portugal ◽  
Ecological Relevance ◽  
Structure And Dynamics ◽  
Population Structure And Dynamics ◽  
Autumn And Winter ◽  
The Relationship ◽  
Fast Increase

This paper reports population dynamics, growth, and reproductive features ofAtyaephyra desmarestii(Millet, 1831) from the estuary of the River Minho. Also, data were compared to information available from its distribution range. Samples were taken monthly between October 2010 and September 2011. Males were less abundant and smaller than females. The growth pattern showed hardly any increase during the autumn and winter, but a fast increase in size was recorded in spring, followed by slower growth in summer. The life span was 11-12 months. The reproductive period was from April to August, and mean fecundity reached 643 ± 254 eggs/female. Juveniles started to appear in July and a strong recruitment occurred in summer and autumn. The ecological relevance of the shrimp supports the need of obtaining further and more specific knowledge on the relationship between geographical distribution and water quality. Our results coupled with longer time series in different localities will be essential to the conservation of the species.

scholarly journals Emergence ecology of the critically endangered Urothemis edwardsii in a new colonized site in El Kala National Park (Algeria): conservation implications

2019 ◽  
pp. 137-142
Author(s):  
Baaloudj Affef
Keyword(s):  
Body Size ◽  
Sex Ratio ◽  
Sexual Size Dimorphism ◽  
The Body ◽  
Microhabitat Selection ◽  
Conservation Implications ◽  
And Behavior ◽  
The Relationship ◽  
The Vertical Distribution ◽  
Dragonfly Species

Urothemis edwardsii is one of the most threatened dragonfly species in the Mediterranean. Recent investigations and conservation efforts have increased the local geographic distribution of the species in Northeast Algeria, where a new population (named El Graeate) has been discovered. In the absence of information about the biology and behavior of U. edwardsii in this new site, a study was conducted on the emergence ecology of the species taking into account the temporal pattern of emergence, sex ratio, body size and microhabitat selection. Emergence, which was quite asynchronous, lasted for 50 days, with 50% of the population emerging within the first half of the period. Sex ratio at emergence was slightly female biased despite the absence of sexual size dimorphism, suggesting that size is not the only driving force behind mortality bias during the larval stage. There was a slight seasonal increase in the body size of exuviae (exoskeletons) in both sexes. Microhabitat selection, assessed as the vertical stratification of exuviae at ecdysis, was positively correlated with the height of supporting plants, but the relationship reached a plateau suggesting that there are predetermined limits to the vertical distribution of exuviae. These data will be essential for the future species protection, restoration and management attempts in the region.

THE RELATIONSHIP BETWEEN SEXUAL SIZE DIMORPHISM AND HABITAT USE IN GREATER ANTILLEAN ANOLIS LIZARDS

Evolution ◽  
2000 ◽  
Vol 54 (1) ◽  
pp. 259 ◽  
Author(s):  
Marguerite A. Butler ◽  
Thomas W. Schoener ◽  
Jonathan B. Losos
Keyword(s):  
Habitat Use ◽  
Sexual Size Dimorphism ◽  
Size Dimorphism ◽  
The Relationship

scholarly journals Evolution of sexual size dimorphism and its relationship with sex ratio in carabid beetles of Genus Ceroglossus Solier

2013 ◽  
Vol 59 (6) ◽  
pp. 769-777 ◽  
Author(s):  
Hugo A. Benítez ◽  
Jorge Avaria-Llautureo ◽  
Cristian B. Canales-Aguirre ◽  
Viviane Jerez ◽  
Luis E. Parra ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Sexual Size Dimorphism ◽  
Phylogenetic Signal ◽  
Comparative Method ◽  
Carabid Beetles ◽  
Entire Group ◽  
Geometrical Shape ◽  
Specific Level ◽  
Size Dimorphism ◽  
Morphological Studies

Abstract Although the degree of mate competition, given extreme differences in sex ratio, explains much of the pattern of male-biased size dimorphism among diverse taxa, it fails for some species which have potential for intense male competition for mates and yet exhibit little or no sexual size dimorphism (SSD). This fact suggest that species with low SSD should be express the effect of evolutionary pressure in non-obvious geometrical shape promoted by sex ratio in an evolutionary time scale. To evaluate this hypothesis we used phylogenetic comparative method in a Bayesian framework to investigate the evolution of SSD and the role of sex ratio at inter-specific level in the species of Ceroglossus (Coleoptera: Carabidae). In our results the proportion farthest from 1:1 is associated with more disparate body shape, even though the entire group has minimum variation in sex ratio, which is an intrinsic life history character of this group considering its phylogenetic conservatism or phylogenetic signal. We suggest that the sex ratio has determined the dimorphism degree during evolution of this group, since both traits have increased or decreased together during the species divergence (i.e. positive phylogenetic correlation: r2≈0.85). We suggest that morphological studies of SSD will benefit from using comparative method with Bayesian approaches to assess the effect of phylogenetic history and its uncertainty. Finally, this will be allow to researchers to quantify the uncertainty of specific evolutionary hypotheses accounting for observed sexual dimorphism patterns.

Male–male contests for mates, sexual size dimorphism, and sex ratio in a natural population of a solitary parasitoid

2013 ◽  
Vol 100 ◽  
pp. 1-8 ◽  
Author(s):  
Margarete V. Macedo ◽  
Ricardo F. Monteiro ◽  
Mariana P. Silveira ◽  
Peter J. Mayhew
Keyword(s):  
Sex Ratio ◽  
Natural Population ◽  
Sexual Size Dimorphism ◽  
Size Dimorphism ◽  
Solitary Parasitoid ◽  
Male Contests

Sexual size dimorphism and food requirements of nestling birds

1993 ◽  
Vol 71 (12) ◽  
pp. 2541-2545 ◽  
Author(s):  
David J. Anderson ◽  
Jo Reeve ◽  
Juan E. Martinez Gomez ◽  
Wesley W. Weathers ◽  
Siobhan Hutson ◽  
...  
Keyword(s):  
Gender Difference ◽  
Sex Ratio ◽  
Sex Allocation ◽  
Sexual Size Dimorphism ◽  
Positive Association ◽  
Size Dimorphism ◽  
American Kestrels ◽  
Sex Allocation Theory ◽  
Strong Positive Association ◽  
And Gender

The food requirements of dependent sons and daughters have important implications for evolution of the sex ratio, according to current sex allocation theory. We studied food requirements of nestling American kestrels (Falco sparverius), a moderately size-dimorphic falcon, by hand-feeding 61 birds from hatching to fledging. Daughters, the larger gender, consumed 6.99% more food than did sons. Sons did not have higher energy expenditure from higher effort during sibling competition than daughters did, so parents must supply more food to satisfy daughters' needs than to satisfy sons'. A review of all related studies shows a strong positive association between the degree of sexual size dimorphism and gender difference in food requirements.

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