Identifying a limiting factor in the population dynamics of a threatened amphibian: The influence of extended female maturation on operational sex ratio

2021 ◽  
Author(s):  
Chad T. Beranek ◽  
Cassandra Maynard ◽  
Colin McHenry ◽  
John Clulow ◽  
Michael Mahony
Keyword(s):  
Population Dynamics ◽  
Sex Ratio ◽  
Operational Sex Ratio ◽  
Limiting Factor ◽  
Female Maturation

scholarly journals Sex Chromosome Meiotic Drive in Stalk-Eyed Flies

Genetics ◽  
1997 ◽  
Vol 147 (3) ◽  
pp. 1169-1180 ◽  
Author(s):  
Daven C Presgraves ◽  
Emily Severance ◽  
Gerald S Willrinson
Keyword(s):  
Sex Ratio ◽  
Sex Chromosome ◽  
Sex Ratios ◽  
Natural Populations ◽  
Meiotic Drive ◽  
Operational Sex Ratio ◽  
Genetic Modifiers ◽  
Ratio Distortion ◽  
The Impact ◽  
Sex Ratio Distortion

Meiotically driven sex chromosomes can quickly spread to fixation and cause population extinction unless balanced by selection or suppressed by genetic modifiers. We report results of genetic analyses that demonstrate that extreme female-biased sex ratios in two sister species of stalk-eyed flies, Cyrtodiopsis dalmanni and C. whitei, are due to a meiotic drive element on the X chromosome (Xd). Relatively high frequencies of Xd in C. dalmanni and C. whitei (13–17% and 29%, respectively) cause female-biased sex ratios in natural populations of both species. Sex ratio distortion is associated with spermatid degeneration in male carriers of Xd. Variation in sex ratios is caused by Y-linked and autosomal factors that decrease the intensity of meiotic drive. Y-linked polymorphism for resistance to drive exists in C. dalmanni in which a resistant Y chromosome reduces the intensity and reverses the direction of meiotic drive. When paired with Xd, modifying Y chromosomes (Ym) cause the transmission of predominantly Y-bearing sperm, and on average, production of 63% male progeny. The absence of sex ratio distortion in closely related monomorphic outgroup species suggests that this meiotic drive system may predate the origin of C. whitei and C. dalmanni. We discuss factors likely to be involved in the persistence of these sex-linked polymorphisms and consider the impact of Xd on the operational sex ratio and the intensity of sexual selection in these extremely sexually dimorphic flies.

Population dynamics of Stenothoe valida Dana, 1852 (Amphipoda, Stenothoidae) at Cheongsapo beach of Busan, Republic of Korea

Crustaceana ◽  
2021 ◽  
Vol 94 (4) ◽  
pp. 413-429
Author(s):  
Ye Ji Lee ◽  
Won Gyu Park
Keyword(s):  
Population Dynamics ◽  
Life History ◽  
Sex Ratio ◽  
Brood Size ◽  
Ovigerous Female ◽  
Seasonal Pattern ◽  
Recruitment Rate ◽  
Republic Of Korea ◽  
Female Size ◽  
History Of

Abstract The population dynamics of Stenothoe valida Dana, 1852 were studied at Cheongsapo beach of Busan, Republic of Korea, from March 2019 to March 2020. Sampling was conducted once a month at low tide during spring tides. Specimens were grouped by the cephalic length at 0.025 mm intervals, and classified into four categories: females, ovigerous females, males and juveniles. The sex ratio, defined as females : total males + females, exceeded 0.5 during most of the study period. Brood size was significantly coupled with ovigerous female size. Two to four cohorts appeared at each study period. New cohorts occurred at almost every sampling except in the samples Jun-2, and Nov-2. Life span was estimated at 1-2 months. The juvenile ratio, the ratio of ovigerous females, and the recruitment rate estimated by FiSAT were commonly high in summer and winter. The life history of S. valida was not coupled with water temperature, but had a strong seasonal pattern.

scholarly journals Deer Indirectly Alter the Reproductive Strategy and Operational Sex Ratio of an Unpalatable Forest Perennial

2020 ◽  
Vol 195 (1) ◽  
pp. 56-69
Author(s):  
Lalasia Bialic-Murphy ◽  
Christopher D. Heckel ◽  
Robert M. McElderry ◽  
Susan Kalisz
Keyword(s):  
Sex Ratio ◽  
Reproductive Strategy ◽  
Operational Sex Ratio

scholarly journals Red fox sex ratio and changes in the number in the Krasnoarmeisky District of the Samara Region

2018 ◽  
Vol 7 (2) ◽  
pp. 111-115
Author(s):  
Olga Aleksandrovna Sklueva ◽  
Valeriy Vitalyevich Sklyuev ◽  
Rafik Ibragimovich Khakimov
Keyword(s):  
Population Dynamics ◽  
Sex Ratio ◽  
Vulpes Vulpes ◽  
Red Fox ◽  
Direct Impact ◽  
Age Composition ◽  
Behavioral Adaptations ◽  
Epizootic Process ◽  
Males And Females ◽  
Homeostatic State

The paper presents some data on the red fox ( Vulpes vulpes , Linnaeus, 1758) sex ratio in the Krasnoarmeysky District of the Samara Region. The results of winter trails traces of mammals show the placement of individual sites of males and females. The authors consider relationship between the population dynamics, sex and age composition and the placement of individual sites. Some aspects of behavioral adaptations and causes of changes in the number of animals in the study area are considered. The influence of a poaching factor on the dynamic indicators of the studied population and the possible danger of the epizootic process is described. A comparative analysis with the previously obtained data on the ratio of males and females in the litter is carried out. The paper indicates possible causes of animals number changes in the study areas. Poaching has a direct impact on the studied population homeostatic state maintaining mechanisms. There is also a forecast of poaching influence on deterioration of epidemiological and epizootic situation in the investigated region. In this paper we give recommendations to minimize possible damage by human activities.

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