Body size and segmentation patterns in free-living and parasitic polychaetes

2001 ◽  
Vol 79 (5) ◽  
pp. 741-745 ◽  
Author(s):  
Robert Poulin

Taxa that include both free-living and parasitic lineages present opportunities to examine if and how the life-history traits of parasitic organisms have diverged from those of their free-living relatives. In a comparative analysis the body sizes and numbers of body segments of parasitic polychaetes of the family Oenonidae were compared with those of free-living polychaetes from closely related families. There was no difference in body length between oenonids and free-living polychaetes. However, the parasitic oenonids attain, on average, a much higher number of body segments than their free-living counterparts. The number of segments per unit body length is also much higher in oenonids than in related free-living polychaetes. This suggests that new segments are produced at a higher rate or for longer periods in oenonids than in free-living polychaetes, in which the proliferation of new segments slows down over time to allow for the segments to grow in size. Given that each segment can produce gametes late in the life of the worm, the proliferation of segments in oenonids may be an adaptation to their parasitic life-style.

2018 ◽  
Vol 63 (4) ◽  
pp. 766-771 ◽  
Author(s):  
Nessrine Ghanmi ◽  
David González-Solís ◽  
Lamia Gargouri

Abstract Helminthological examinations of the red mullet Mullus barbatus (Linnaeus) (Mullidae) from the Gulf of Hammamet, off Tunisia, revealed the presence of one undescribed gonad-infecting nematode species, Philometra barbata n. sp. (Philometridae). The new species as other congeneric species is mainly characterized by the shape of the caudal mound, the distribution of the caudal papillae and the shape of the gubernaculum with the presence of a dorsal protuberance consisting of two dorsolateral lamellar parts separated from each other by a smooth median field in the male. The new species differs from its gonadinfecting congeners in the body length of male, the length of spicules and gubernaculum. This is the second nominal species of Philometra reported from fishes of the family Mullidae and the 14th from the Mediterranean Sea.


2006 ◽  
Vol 66 (1a) ◽  
pp. 85-93 ◽  
Author(s):  
M. I. Hamann

From December 1995 to November 2000, the seasonal maturation of Glypthelmins vitellinophilum Dobbin, 1958, in its definitive host, the frog Lysapsus limellus Cope, 1862, was studied in a subtropical permanent pond in northeastern Argentina. The objectives of this study were: 1) to determine the infrapopulation dynamics of the parasite, analyzing the seasonal maturation cycle throughout the years; and 2) to examine the relationship between the intensity of trematode infection in different developmental stages (recruitment, growth and maturation) and the host's body length. Of a total of 1,400 frogs examined over 60 months (5 years), 38% were found to be infected with G. vitellinophilum, and the intensity of infection was 1-15 trematodes per frog. Specimens of G. vitellinophilum were present in L. limellus throughout the years, but did not show a pronounced seasonal maturation cycle. Possible reasons for these findings are discussed with reference to climatic fluctuations and biotic factors. The infective period of the parasite (stage I) occurred in summer, autumn and spring, coinciding with the time each frog cohort appeared. These infections were found principally in small body sizes (classes 1 and 2) of L. limellus. Juvenile and nongravid specimens of worms (stage II and III) were found in frogs of different body sizes throughout the period of investigation. Gravid specimens of the parasite (stage IV) were generally recorded in autumn, winter and spring, mainly in the bodies of larger frogs. The body length of Trematodes in stages I and IV was significantly and positively correlated with that of the frogs.


Zoosymposia ◽  
2021 ◽  
Vol 20 ◽  
Author(s):  
LIANA JOHANN ◽  
GUILHERME LIBERATO DA SILVA

The family Tydeidae consists of small, free-living, soft-bodied mites with a diversity of feeding habits, including phytophages, pollen feeders and even predators, but the majority are scavengers or fungivores. Approximately 330 species in 30 genera have been described from throughout the world, but only a few species (<1% of all species) have been studied for their life history. This review provides a survey of their life history with a focus on their lifespan.


Zootaxa ◽  
2020 ◽  
Vol 4763 (3) ◽  
pp. 354-370
Author(s):  
GABRIEL CIDREIRA ◽  
VIRÁG VENEKEY ◽  
ORANE F. DE SOUZA ALVES ◽  
FRANCISCO KELMO

A new free-living marine nematode of the family Xyalidae is described from Armação Beach, northeastern Brazil, and the genus Pseudosteineria is reviewed. Pseudosteineria longisetis sp. n. is characterized by having six groups of long subcephalic setae, amphids situated slightly anterior to the groups of subcephalic setae or at the level of the first subcephalic setae, long somatic setae located posteriorly to subcephalic setae and distributed along the body, one papiliform precloacal supplement, and gubernaculum with dorso-caudal apophysis. An emended diagnosis of the genus, an updated list of species and dichotomous identification key, and a pictorial key are given. A comparative table including the main characters of all Pseudosteineria species is also provided. 


2012 ◽  
Vol 8 (6) ◽  
pp. 1059-1062 ◽  
Author(s):  
Jonathan Z. Shik ◽  
Chen Hou ◽  
Adam Kay ◽  
Michael Kaspari ◽  
James F. Gillooly

Social insect societies dominate many terrestrial ecosystems across the planet. Colony members cooperate to capture and use resources to maximize survival and reproduction. Yet, when compared with solitary organisms, we understand relatively little about the factors responsible for differences in the rates of survival, growth and reproduction among colonies. To explain these differences, we present a mathematical model that predicts these three rates for ant colonies based on the body sizes and metabolic rates of colony members. Specifically, the model predicts that smaller colonies tend to use more energy per gram of biomass, live faster and die younger. Model predictions are supported with data from whole colonies for a diversity of species, with much of the variation in colony-level life history explained based on physiological traits of individual ants. The theory and data presented here provide a first step towards a more general theory of colony life history that applies across species and environments.


Behaviour ◽  
2018 ◽  
Vol 155 (4) ◽  
pp. 295-326 ◽  
Author(s):  
Karina Charest Castro ◽  
Mathieu Leblond ◽  
Steeve D. Côté

Abstract To better understand the potential costs and benefits of prolonged parental care in gregarious species, we studied post-weaning associations in a marked population of mountain goats (Oreamnos americanus) monitored for 22 years. We calculated the occurrence and frequency of associations involving 1- and 2-year-old juveniles. We investigated (1) the influence of maternal characteristics and population size on the formation of post-weaning associations, (2) the short-term costs of associations on maternal reproductive success, and (3) the short-term benefits of associations on life-history traits of juveniles. We found that barren mothers associated more frequently with 1-year-olds than summer yeld and lactating mothers. Associations with 2-year-olds tended to increase the probability that a mother would be barren the following year. Post-weaning associations did not influence the body mass of newborn kids nor the body mass and survival of juveniles. We discuss how benefits for associated juveniles may appear later in life.


Author(s):  
V. Lo Russo ◽  
G. Villares ◽  
A. Martelli ◽  
C.T. Pastor de Ward ◽  
C. Harguinteguy

Two new free-living marine nematodes belonging to the family Thoracostomopsidae, subfamily Enoplolaiminae and the generaEpacanthionare described from Patagonian coastal areas, Río Negro and Chubut provinces of Argentina. InEpacanthion bicuspidatumsp. nov. the main features are: two cusps on distal mandible end; presence of two rings of eight setae in the cervical region; and eight crown-shaped setae along the body, presence of one supplement distant two cloacal body diameter (cbd) from cloacae, gubernaculum and short spicule.Epacanthion ampullatumsp. nov. is characterized by having a tubular and long pre-cloacal supplement, short spicule, presence of gubernaculum, presence of three long setae on the tip of the tail, the presence of one supplement distant three cbd from cloacae and the presence of two small cusps on the distal end of the mandible.


Herpetozoa ◽  
2019 ◽  
Vol 32 ◽  
pp. 211-219
Author(s):  
Gabriel Suárez-Varón ◽  
Orlando Suárez-Rodríguez ◽  
Gisela Granados-González ◽  
Maricela Villagrán-Santa Cruz ◽  
Kevin M. Gribbins ◽  
...  

Clutch size (CS) and relative clutch mass (RCM) are considered important features in life history descriptions of species within Squamata. Variations in these two characteristics are caused by both biotic and abiotic factors. The present study provides the first account related to CS and RCM ofBasiliscus vittatusin Mexico within a population that inhabits an open riverbed juxtapositioned to tropical rainforest habitat in Catemaco, Veracruz, Mexico (170 m a.s.l.). Twenty-nine gravid females were collected and kept in captivity under favorable conditions that promote oviposition. The CS within this population was 6.2 ± 0.2 and was correlated positively with snout vent-length (SVL); while the RCM was 0.17 ± 0.006 and was correlated positively with both CS and width of egg. Factors, such as female morphology and environmental conditions, should influence these reproductive traits inB. vittatus. The data collected in this study could provide a framework for comparisons of the life history traits across populations ofB. vittatusin Mexico and within other species of the family Corytophanidae and provide a model for testing how abiotic and biotic factors may influence the CS and RCM in basilisk lizards throughout their range.


2020 ◽  
Vol 15 (4) ◽  
pp. 561-569
Author(s):  
Filipe Martins Santos ◽  
David Risco ◽  
Nayara Yoshie Sano ◽  
Gabriel Carvalho de Macedo ◽  
Wanessa Teixeira Gomes Barreto ◽  
...  

Assessing and monitoring the welfare of free-living mammals is not a usual process due to the logistical complications associated with their capture and sedation, collection and storage of biological samples and their release. In this context, non-invasive methods for monitoring wildlife constitute a good alternative approach for in situ conservation. Body condition index, as a measurement of health status, has been used in free-living mammals; its low value may be associated with negative effects on reproduction and survival. The present study aimed to generate an alternative and reliable non-invasive method and then determine the body condition index, based on previously-collected biometric measurements, without the need to capture and immobilise the animals. A total of 178 free-living Nasua nasua Linnaeus, 1766 were trapped, weighed and measured. Statistical methods were used, based on Boosted Regression Trees (BRT) using body mass, biometric measurements (body length, height and chest girth) and gender as explanatory variables. To assess the agreement between the real Body Condition Indices (BCIs) and the predicted values of BCIs, we explored the correlation between each model using the Bland-Altman method. This method showed a strong agreement between the predictive BRT models proposed (standardised residuals from a linear regression between body length and chest girth) and standardised residuals (linear regression between body mass and body length). The results obtained herein showed that BRT modelling, based on biometrical features, is an alternative way to verify the body conditions of coatis without the need to capture and immobilise the animals.


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