scholarly journals PARASITE LOAD, BODY SIZE, AND AGE OF WILD-CAUGHT MALE FIELD CRICKETS (ORTHOPTERA: GRYLLIDAE): EFFECTS ON SEXUAL SELECTION

Evolution ◽  
1988 ◽  
Vol 42 (5) ◽  
pp. 969-976 ◽  
Author(s):  
Marlene Zuk
Keyword(s):  
Sexual Selection ◽  
Body Size ◽  
Parasite Load ◽  
Field Crickets

Size does not matter for male Marbled Salamanders (Ambystoma opacum)

2015 ◽  
Vol 93 (10) ◽  
pp. 735-740
Author(s):  
D.A. Croshaw ◽  
J.H.K. Pechmann
Keyword(s):  
Sexual Selection ◽  
Body Size ◽  
Reproductive Success ◽  
Large Male ◽  
Male Mating ◽  
Ambystoma Opacum ◽  
Positive Assortative Mating ◽  
Important Trait ◽  
Breeding Groups ◽  
Gravid Females

Understanding the phenotypic attributes that contribute to variance in mating and reproductive success is crucial in the study of evolution by sexual selection. In many animals, body size is an important trait because larger individuals enjoy greater fitness due to the ability to secure more mates and produce more offspring. Among males, this outcome is largely mediated by greater success in competition with rival males and (or) advantages in attractiveness to females. Here we tested the hypothesis that large male Marbled Salamanders (Ambystoma opacum (Gravenhorst, 1807)) mate with more females and produce more offspring than small males. In experimental breeding groups, we included males chosen specifically to represent a range of sizes. After gravid females mated and nested freely, we collected egg clutches and genotyped all adults and samples of hatchlings with highly variable microsatellite markers to assign paternity. Size had little effect on male mating and reproductive success. Breeding males were not bigger than nonbreeding males, mates of polyandrous females were not smaller than those of monogamous females, and there was no evidence for positive assortative mating by size. Although body size did not matter for male Marbled Salamanders, we documented considerable fitness variation and discuss alternative traits that could be undergoing sexual selection.

Body size, not age, predicts parasite load in Clark’s Spiny Lizards (Sceloporus clarkii)

2019 ◽  
Vol 97 (3) ◽  
pp. 220-224 ◽  
Author(s):  
H.V. Watkins ◽  
G. Blouin-Demers
Keyword(s):  
Body Size ◽  
Surface Area ◽  
Intraspecific Variation ◽  
Wild Population ◽  
Parasite Load ◽  
Older Individuals ◽  
Fundamental Goal ◽  
Males And Females ◽  
Ectoparasite Load

Determining the factors that influence parasite load is a fundamental goal of parasitology. Body size often influences parasite load in reptiles, but it is unclear whether higher levels of parasitism are a result of greater surface area of individuals (a function of size) or of longer periods of exposure to parasites (a function of age). Using skeletochronology in a wild population of Clark’s Spiny Lizards (Sceloporus clarkii Baird and Girard, 1852), we tested the hypotheses that (i) larger individuals have higher parasite loads due to increased surface area available for colonization by parasites and their vectors and that (ii) older individuals have higher parasite loads because they have had longer exposure to parasites and their vectors. Males harboured more ectoparasites than females. Males and females differed in how body size influenced chigger (Acari: Trombiculidae) load; larger males harboured more chiggers than smaller males, but this was not the case in females. Age did not affect ectoparasite load in either sex. These results emphasize the importance of disentangling the effects of size and age in models of parasitism to gain a clearer understanding of intraspecific variation in parasite load.

Sexual Selection and Body Size in Male Red-Winged Blackbirds

Evolution ◽  
1979 ◽  
Vol 33 (2) ◽  
pp. 649 ◽  
Author(s):  
William A. Searcy
Keyword(s):  
Sexual Selection ◽  
Body Size

scholarly journals Infection patterns of helminths in Norops brasiliensis (Squamata, Dactyloidae) from a humid forest, Northeastern Brazil and their relation with body mass, sex, host size, and season

2019 ◽  
Vol 56 (2) ◽  
pp. 168-174 ◽  
Author(s):  
D. M. Amorim ◽  
R. W. Ávila
Keyword(s):  
Body Size ◽  
Ecological Factors ◽  
Parasite Load ◽  
Helminth Fauna ◽  
Northeastern Brazil ◽  
Rainfall Regime ◽  
New Host ◽  
Humid Forest ◽  
Host Sex ◽  
New Host Records

SummaryClimatic and ecological factors can influence the parasite load of a host. Variation in rainfall, body size, and sex of the hosts may be related to the abundance of parasites. This study investigated the helminth fauna associated with a population of Norops brasiliensis, together with the effect of host biology (sex, body size, and mass) and variation in rainfall regime on the abundance of helminths. Species of three groups of endoparasites were found (Nematoda, Cestoda, and Trematoda), with nematodes as the most representative taxa with eight species, prevalence of 63.2 %, mean intensity of 4.0 ± 0.58 (1 – 25), and mean abundance of 2.66 ± 0.44 (0 – 25). Nine helminth species are new host records for N. brasiliensis. The nematode Rhabdias sp. had the highest prevalence (53.3 %). There was no significant relationship between abundance of the trematode Mesocoelium monas and host sex or season, although the abundance of this parasite increased significantly with host body size and mass, while abundance of nematodes was related to season and host mass. This study increases the knowledge about the diversity of helminth fauna associated with N. brasiliensis, revealing infection levels of hosts from northeastern Brazil.

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