scholarly journals Decline in body size and female fraction in the grass snake (Natrix natrix, Linnaeus 1758) population after 40 years (Southern Poland)

2021 ◽  
Author(s):  
Stanisław Bury ◽  
Bartłomiej Zając ◽  
Henryk Okarma ◽  
Aleksandra Kolanek
Keyword(s):  
Body Size ◽  
Sex Ratio ◽  
Road Traffic ◽  
Prey Availability ◽  
Reproductive Potential ◽  
Environmental Pressures ◽  
Ambient Temperatures ◽  
Natrix Natrix ◽  
Resource Requirements ◽  
Grass Snake

AbstractDepletion of free-living populations is often associated with changes in fitness-related traits, e.g., body size. Ongoing decrease in body size has been reported in most vertebrates, but reptiles remain understudied. Moreover, sexual size dimorphism, commonly observed in reptiles, indicates that environmental pressures on body size may appear sex-specific. This can also result in shifts in sex ratio, an aspect even less studied. We investigated body size and sex ratio in population of grass snake (Natrix natrix) surveyed over 40 years ago in comparison with the current state. We found that both sexes express similar magnitude in body size decline. The current sex ratio does not deviate from 1:1, while in the past, females outnumbered males. The observed changes are likely an outcome of several non-mutually exclusive factors. In the studied area, an increase in road traffic and human presence and a drop in prey availability have been documented. Both factors may exert higher pressure on larger individuals, particularly females, due to their high costs of reproduction. It is recorded here that increase in ambient temperatures and summer duration may additionally enhance the mortality risk and resource requirements. Shifts in body size and sex ratio can catalyze further declines in abundance and reproductive potential of the population.

scholarly journals Decline in Body Size and Female Fraction in the Grass Snake (Natrix Natrix, Linnaeus 1758) Population After 40 Years (Southern Poland)

2021 ◽  
Author(s):  
Stanisław Bury ◽  
Bartłomiej Zając ◽  
Henryk Okarma ◽  
Aleksandra Kolanek
Keyword(s):  
Body Size ◽  
Sex Ratio ◽  
Road Traffic ◽  
Prey Availability ◽  
Reproductive Potential ◽  
Environmental Pressures ◽  
Ambient Temperatures ◽  
Natrix Natrix ◽  
Resource Requirements ◽  
Grass Snake

Abstract Depletion of free-living populations is often associated with changes in fitness-related traits, e.g. body size. Ongoing decrease in body size has been reported in most vertebrates, but reptiles remain understudied. Moreover, sexual size dimorphism, commonly observed in reptiles, indicates that environmental pressures on body size may appear sex-specific. This can also result in shifts in sex ratio, an aspect even less studied. We investigated body size and sex ratio in population of grass snake (Natrix natrix) surveyed over 40 years ago in comparison with the current state. We found that both sexes express similar magnitude in body size decline. The current sex ratio does not deviate from 1:1, while in the past females outnumbered males. The observed changes are likely an outcome of several non-mutually exclusive factors. In the studied area an increase in road traffic, human presence and a drop in prey availability has been documented. Both factors may exert higher pressure on larger individuals, particularly females, due to their high costs of reproduction. Recorded here increase in ambient temperatures and summer duration, may additionally enhance the mortality risk and resource requirements. Shifts in body size and sex ratio can catalyze further declines in abundance and reproductive potential of the population.

scholarly journals Melanism, body size, and sex ratio in snakes—new data on the grass snake (Natrix natrix) and synthesis

2020 ◽  
Vol 107 (3) ◽  
Author(s):  
Stanisław Bury ◽  
Tomasz D. Mazgajski ◽  
Bartłomiej Najbar ◽  
Bartłomiej Zając ◽  
Katarzyna Kurek
Keyword(s):  
Body Size ◽  
Sex Ratio ◽  
Natrix Natrix ◽  
Grass Snake

Temperature Influences on Adult Size, Development, and Reproductive Potential of Aquatic Diptera

1987 ◽  
Vol 44 (10) ◽  
pp. 1743-1752 ◽  
Author(s):  
Robert S. Rempel ◽  
John C. H. Carter
Keyword(s):  
Body Size ◽  
Elevated Temperature ◽  
Reproductive Potential ◽  
Somatic Growth ◽  
Adult Size ◽  
Trophic Groups ◽  
Energy Reserves ◽  
Ambient Temperatures ◽  
Kolmogorov Smirnov ◽  
Smirnov Test

Elevated temperature (2.5 and 4.0 °C) resulted in smaller body size of stream Diptera in outdoor experimental channels, and this trend applied to both predator and detritivore trophic groups. Comparison of cumulative emergence curves using the Kolmogorov–Smirnov test showed that most species developed more quickly in the heated channels; this led to greater overall survivorship. Reproductive potential, estimated from ovary area, did not change with body size for Conchapelopia aleta, Polypedilum aviceps, and Stempellinella brevis, and did so only weakly for Parametriocnemus lundbecki. In addition, females decreased in size more than males in the heated channels. Somatic growth appeared to be sacrificed to maintain reproductive potential, although loss of energy reserves could reduce the length of the reproductive stage. In balance, the aquatic Diptera demonstrated resistance to thermal elevation in the summer, even though ambient temperatures approached 30 °C. This may partially account for the group's ability to grow and develop throughout the year in extremely varied temperate environments.

scholarly journals Long-Term Changes in the Diet of Gymnogobius isaza from Lake Biwa, Japan: Effects of Body Size and Environmental Prey Availability

PLoS ONE ◽  
2012 ◽  
Vol 7 (12) ◽  
pp. e53167 ◽  
Author(s):  
Jonathan Carlo Briones ◽  
Cheng-Han Tsai ◽  
Takefumi Nakazawa ◽  
Yoichiro Sakai ◽  
Rey Donne S. Papa ◽  
...  
Keyword(s):  
Body Size ◽  
Lake Biwa ◽  
Prey Availability ◽  
Long Term Changes

II.—Hidden Divergence in Laboratory Strains of Drosophila pseudo-obscura

1944 ◽  
Vol 62 (1) ◽  
pp. 9-19 ◽  
Author(s):  
Rowena Lamy
Keyword(s):  
Body Size ◽  
Sex Ratio ◽  
Genetic Constitution ◽  
Low Grade ◽  
Testis Size ◽  
Hybrid Female ◽  
Back Cross ◽  
Pure Race ◽  
Range Of Variation

The Race A/Race B hybrid females of D. pseudo-obscura have a high percentage of fertility, comparable with that of females of pure race. The number and viability of their offspring, however, are largely affected by the genetic constitution of the hybrid female as well as by that of the male to which she is mated in the backcross. Hence the performance of any given hybrid is determined in the first instance by the actual strains of the pure races which are used in making the P1 racial cross. Generally speaking the results are of the same order whenever the same strains are used. The progenies of hybrid females of different genetic constitution may differ in three main aspects: (1) The total number of offspring may be comparable with that usually obtained in a pure race cross; it may be reduced to any extent; in certain matings it is consistently at zero. (2) The sex ratio may be completely normal or male-deficient or female-deficient in any degree; completely uni-sexual progenies are sometimes obtained. (The above observations are mainly in agreement with reports of earlier writers; cf. Lancefield, 1929, Dobzhansky, 1936, Mampell, 1941, Sturtevant, 1937.) (3) “Viability characters,” i.e. those affecting general vigour and physical normality, may be of a high or a low grade; some progenies are comparable in this respect with the pure race, the only exception being that they show a much greater range of variation in body-size of both sexes, and in the testis size of males, abnormalities which are common to all back-cross progenies whatever the genetic constitution of the mother or father. Some progenies show in addition deformities of a peculiar type usually affecting the abdomen and occasionally the legs and wings.

Variation in Weight, Size, and Sex Ratio of Coccinellid Adults (Coleoptera: Coccinellidae)

1966 ◽  
Vol 98 (6) ◽  
pp. 639-644 ◽  
Author(s):  
B. C. Smith
Keyword(s):  
Body Size ◽  
Sex Ratio ◽  
Water Content ◽  
Food Supply ◽  
Sexual Differences ◽  
Intraspecies Variation ◽  
Food Scarcity ◽  
Food Requirement ◽  
Males And Females

AbstractThe weight and size of coccinellid adults varied with species, sex, and feeding. Intraspecies variation in weight was generally similar in the eight species studied. Females were more variable than males in body size. Females of some species were heavier and larger than males, and species can be classified on a basis of difference in the weight and size of the sexes.An increase in the food supply after a period of food scarcity affected the sex ratio, as the minimum food requirement of females was greater than males. Females increased in weight more rapidly than males after feeding. The availability of food in the field affected the weight and size of some species. Adult water content was influenced by feeding but not by sex or the quantity of food given to the larva.Males were more abundant in species with small sexual differences in weight and size. The degree of difference in weight and size between males and females may be used as a criterion to select species that are best adapted to survive when food is scarce.

Ovigeny strategy of the parasitic wasp Cosmocomoidea annulicornis (Hymenoptera: Mymaridae): effect of female age, feeding and host availability on reproductive traits

2021 ◽  
pp. 1-8
Author(s):  
Carolina Manzano ◽  
Eduardo G. Virla ◽  
Maria V. Coll Araoz ◽  
Erica Luft-Albarracin
Keyword(s):  
Body Size ◽  
Parasitic Wasp ◽  
Reproductive Potential ◽  
Reproductive Traits ◽  
Egg Load ◽  
Biological Traits ◽  
Potential Fecundity ◽  
Female Age ◽  
Host Availability ◽  
Egg Maturation

Abstract The reproductive traits of the mymarid wasp Cosmocomoidea annulicornis (Ogloblin) (Hymenoptera: Mymaridae) attacking eggs of the sharpshooter Tapajosa rubromarginata (Signoret) (Hemiptera: Cicadellidae) were evaluated under laboratory conditions. Bioassays were carried out to estimate the realized fecundity and egg load of females. The ovigeny index was calculated and different biological traits, such as body size, oöcyte length, gaster length and wing length, were analysed to assess significant associations between these traits and the species fitness. In addition, the effect of host availability and feeding on longevity and potential fecundity throughout life and the effect of female age on egg maturation dynamics were assessed. The results showed that C. annulicornis is a strongly synovigenic species. A positive correlation was found between fecundity and longevity of the females and between body size and oöcyte length. Contrary to expected, body size was not related to fecundity and longevity. Females lived significantly longer in the presence of hosts and honey than when they were host-deprived and honey-fed or both host and honey deprived. Host availability had a significant effect on the amount of eggs laid by C. annulicornis females. Female age was negatively associated with oöcyte length. Furthermore, females were able to mature additional eggs as they aged, nevertheless, when host-deprived, senescent females presented significantly less mature eggs than younger ones, suggesting a possible egg oosorption. These results might contribute to a better understanding of the reproductive potential of this species as a biocontrol agent.

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