SPATIAL AND TEMPORAL VARIATION IN ABUNDANCE, SEX RATIO, AND SPECIES COMPOSITION OF CONNECTICUT RHAGIONIDAE (DIPTERA)

1987 ◽  
Vol 119 (1) ◽  
pp. 55-65
Author(s):  
Chris T. Maier ◽  
Donald W. Webb
Keyword(s):  
Sex Ratio ◽  
Species Composition ◽  
Temporal Variation ◽  
Sex Ratios ◽  
The State ◽  
Spatial And Temporal Variation ◽  
Emergence Traps ◽  
Relative Abundances ◽  
Malaise Traps

AbstractRhagionids were studied principally by capturing adults in emergence traps at Southington (1979) and in Malaise traps at Hamden (1980–1983) and Guilford, CT (1983–1985). Most captures of Chrysopilus rotundipennis Loew, C. thoracicus (Fabr.), Rhagio mystaceus (Say), and Symphoromyia hirta Johnson occurred during a 2- to 5-week period. Mean capture dates for sexes differed significantly in only a few cases. Based on percentage of total captured, S. hirta and R. mystaceus ranked first and second at Hamden whereas C. rotundipennis and S. hirta had these respective ranks at Guilford. The sex ratio of C. ornatus (Say) adults in emergence traps did not depart significantly from 1.0, but most rhagionids captured in Malaise traps had skewed sex ratios. Based on percentage and quotient of similarity, faunas at Hamden and Guilford shared many species, but relative abundances of species common at one or both sites were very different. In this study, we found 14 rhagionid species, including 4 not previously recorded from Connecticut. A total of 16 species are now recorded from the state.

scholarly journals Sex-specific deaths in Norway and Sweden during the COVID-19 pandemic: Did mandates make a difference?

2021 ◽  
pp. 140349482110100
Author(s):  
Ralph Catalano
Keyword(s):  
Sex Ratio ◽  
Infection Control ◽  
Temporal Variation ◽  
Risky Behavior ◽  
Control Strategies ◽  
Sex Ratios ◽  
Female Mortality ◽  
All Cause Mortality ◽  
Societal Expectations ◽  
Male To Female

Aims: To determine whether differences between Norway’s and Sweden’s attempts to contain SARS-CoV-2 infection coincided with detectably different changes in their all-cause mortality sex ratios. Measuring temporal variation in the all-cause mortality sex ratio before and during the pandemic in populations exposed to different constraints on risky behavior would allow us to better anticipate changes in the ratio and to better understand its association with infection control strategies. Methods: I apply time Box–Jenkins modeling to 262 months of pre-pandemic mortality sex ratios to arrive at counterfactual values of 10 intra-pandemic ratios. I compare counterfactual to observed values to determine if intra-pandemic ratios differed detectably from those expected as well as whether the Norwegian and Swedish differences varied from each other. Results: The male to female mortality sex ratio in both Norway and Sweden increased during the pandemic. I, however, find no evidence that the increase differed between the two countries despite their different COVID-19 containment strategies. Conclusion: Societal expectations of who will die during the COVID-19 pandemic will likely be wrong if they assume pre-pandemic mortality sex ratios because the intra-pandemic ratios appear, at least in Norway and Sweden, detectably higher. The contribution of differences in policies to reduce risky behavior to those higher ratios appears, however, small.

Sex ratio variation in gastrointestinal nematodes of Svalbard reindeer; density dependence and implications for estimates of species composition

Parasitology ◽  
2004 ◽  
Vol 130 (1) ◽  
pp. 99-107 ◽  
Author(s):  
A. STIEN ◽  
M. DALLIMER ◽  
R. J. IRVINE ◽  
O. HALVORSEN ◽  
R. LANGVATN ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Species Composition ◽  
Density Dependence ◽  
Sex Ratios ◽  
Gastrointestinal Nematodes ◽  
Late Winter ◽  
Adult Males ◽  
Svalbard Reindeer ◽  
Ratio Variation ◽  
Adult Sex Ratio

Estimates of the intensity and abundance of species provide essential data for ecological, evolutionary and epidemiological studies of gastrointestinal nematode communities. These estimates are typically derived from the species composition of adult males when only males have readily scorable species-specific morphological traits. Such estimation assumes that all species in the community have the same adult sex ratio. We evaluated this assumption for the trichostrongyle nematodes Ostertagia gruehneri and Marshallagia marshalli in infracommunities in Svalbard reindeer by identifying to species adult females using a polymerase chain reaction assay. The proportion of males was found to be slightly higher in O. gruehneri than in M. marshalli. Evidence for seasonal variation and density dependence in the adult sex ratio was only found for O. gruehneri. Possible demographic mechanisms for such sex ratio variation are discussed, and stochastic models that generate density-dependent sex ratios proposed. Sex ratio variation caused substantial bias in some male-based estimates of intensity of infection, while substantial and consistent bias in estimates of abundances was only evident in late winter samples. Our results suggest that estimating sex ratios can be particularly important in individual host level studies of nematode species of low abundance.

scholarly journals Estimating adult sex ratios in nature

2017 ◽  
Vol 372 (1729) ◽  
pp. 20160313 ◽  
Author(s):  
Sergio Ancona ◽  
Francisco V. Dénes ◽  
Oliver Krüger ◽  
Tamás Székely ◽  
Steven R. Beissinger
Keyword(s):  
Sex Differences ◽  
Sex Ratio ◽  
Evolutionary Biology ◽  
Adult Population ◽  
Sex Ratios ◽  
Estimation Methods ◽  
Spatial And Temporal Variation ◽  
Animal Populations ◽  
Adult Sex Ratio ◽  
Males And Females

Adult sex ratio (ASR, the proportion of males in the adult population) is a central concept in population and evolutionary biology, and is also emerging as a major factor influencing mate choice, pair bonding and parental cooperation in both human and non-human societies. However, estimating ASR is fraught with difficulties stemming from the effects of spatial and temporal variation in the numbers of males and females, and detection/capture probabilities that differ between the sexes. Here, we critically evaluate methods for estimating ASR in wild animal populations, reviewing how recent statistical advances can be applied to handle some of these challenges. We review methods that directly account for detection differences between the sexes using counts of unmarked individuals (observed, trapped or killed) and counts of marked individuals using mark–recapture models. We review a third class of methods that do not directly sample the number of males and females, but instead estimate the sex ratio indirectly using relationships that emerge from demographic measures, such as survival, age structure, reproduction and assumed dynamics. We recommend that detection-based methods be used for estimating ASR in most situations, and point out that studies are needed that compare different ASR estimation methods and control for sex differences in dispersal. This article is part of the themed issue ‘Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies’.

Living with an engineer: fish metacommunities in dynamic patchy environments

2018 ◽  
Vol 69 (6) ◽  
pp. 883 ◽  
Author(s):  
Aneta Bylak ◽  
Krzysztof Kukuła
Keyword(s):  
Community Structure ◽  
Species Composition ◽  
Temporal Variation ◽  
Fish Species ◽  
Environmental Heterogeneity ◽  
Size Structure ◽  
Local Communities ◽  
Spatial And Temporal Variation ◽  
The Creation ◽  
Fish Species Composition

Different environmental preferences and dispersal abilities allow fish to coexist in local communities. In the present study we analysed the effects of engineering species on the community structure based on the example of the European beaver (Castor fiber) and mountainous European stream fish. We hypothesised that the creation of beaver impoundments increases environmental heterogeneity and causes a strong spatial and temporal variation in fish species composition and size structure. Finally, we placed these results in the context of the metacommunity theory. Our research was conducted over a large spatial scale, and over a relatively long (5-year) temporal scale. Data analysis revealed strong environmental gradients associated with stream size and increased environmental heterogeneity associated with the creation of beaver impoundments. The results also indicated strong spatial and temporal variation in fish species composition and size structure associated with this environmental heterogeneity. Although local communities changed over time, the main metacommunity characteristics remained constant. Fish must move and follow environmental changes for their populations and communities to persist in streams inhabited by beavers. Gaining a deeper understanding of the effects of the engineering species on fish community structure may help inform management and the conservation of stream ecosystems.

scholarly journals Spatial and temporal variation in nest temperatures forecasts sex ratio skews in a crocodilian with environmental sex determination

2020 ◽  
Vol 287 (1926) ◽  
pp. 20200210
Author(s):  
Samantha L. Bock ◽  
Russell H. Lowers ◽  
Thomas R. Rainwater ◽  
Eric Stolen ◽  
John M. Drake ◽  
...  
Keyword(s):  
Climate Change ◽  
Sex Ratio ◽  
Sex Determination ◽  
Temperature Variation ◽  
Climatic Factors ◽  
Sex Ratios ◽  
Alligator Mississippiensis ◽  
Spatial And Temporal Variation ◽  
Nest Temperature ◽  
Offspring Sex

Species displaying temperature-dependent sex determination (TSD) are especially vulnerable to the effects of a rapidly changing global climate due to their profound sensitivity to thermal cues during development. Predicting the consequences of climate change for these species, including skewed offspring sex ratios, depends on understanding how climatic factors interface with features of maternal nesting behaviour to shape the developmental environment. Here, we measure thermal profiles in 86 nests at two geographically distinct sites in the northern and southern regions of the American alligator's ( Alligator mississippiensis ) geographical range, and examine the influence of both climatic factors and maternally driven nest characteristics on nest temperature variation. Changes in daily maximum air temperatures drive annual trends in nest temperatures, while variation in individual nest temperatures is also related to local habitat factors and microclimate characteristics. Without any compensatory nesting behaviours, nest temperatures are projected to increase by 1.6–3.7°C by the year 2100, and these changes are predicted to have dramatic consequences for offspring sex ratios. Exact sex ratio outcomes vary widely depending on site and emission scenario as a function of the unique temperature-by-sex reaction norm exhibited by all crocodilians. By revealing the ecological drivers of nest temperature variation in the American alligator, this study provides important insights into the potential consequences of climate change for crocodilian species, many of which are already threatened by extinction.

Sign in / Sign up

Export Citation Format

Share Document