2,898 research outputs found
Frequency distribution of conception dates in a white-tailed deer herd
Conception dates of white-tailed deer, Odocoi/eus virginia1111s (Zinunennann, 1780) were estimated for the breeding periods of 1974 - 76 and 1984 using fall and winter- spring fetal data. Conception dates estimated from data collected in the fall were biased. This bias resulted in an earlier mean conception date than that based on information which included data from later breeding females. Mean breeding dates differed significantly between female age classes due to delayed conception in fawns which also resulted in a skewed frequency distribution of conception dates. The frequency distribution of conception dates was leptokurtotic, suggesting that the distribution is constrnincd in time by some factor(s). Conception date estimates did not differ by habitat type but were influenced significantly by period of data collection. Mean breeding date for deer on Lhe Savannah River Site, corrected for age class sampling bias, is 20 November± 27 days (adults plus fawns) and 13 November± 15 days (only adults)
Frequency distribution of conception dates in a white-tailed deer herd
Conception dates of white-tailed deer, Odocoi/eus virginia1111s (Zinunennann, 1780) were estimated for the breeding periods of 1974 - 76 and 1984 using fall and winter- spring fetal data. Conception dates estimated from data collected in the fall were biased. This bias resulted in an earlier mean conception date than that based on information which included data from later breeding females. Mean breeding dates differed significantly between female age classes due to delayed conception in fawns which also resulted in a skewed frequency distribution of conception dates. The frequency distribution of conception dates was leptokurtotic, suggesting that the distribution is constrnincd in time by some factor(s). Conception date estimates did not differ by habitat type but were influenced significantly by period of data collection. Mean breeding date for deer on Lhe Savannah River Site, corrected for age class sampling bias, is 20 November± 27 days (adults plus fawns) and 13 November± 15 days (only adults)
Assessment of Fawn Breeding in a South Carolina Deer Herd
Annual variation in breeding success among female white-tailed deer (Odocoileus virginianus) fawns on the Savannah River Plant (1967 to 1985) was determined from direct counts of pregnancy in spring-collected fawn females and evidence of lactation and measurements of udder thickness in fall-harvested 1. 5-yearolds. Percent lactation in 1.5-year-old females collected during September and October gave the best estimate of fawn breeding in the previous year. The overall mean fawn breeding estimate from September and October was 41 % , and the yearly variation in fawn breeding was significant. An estimate of the average yearly contribution to recruitment was 43 fetuses per 100 fawn females
Assessment of Fawn Breeding in a South Carolina Deer Herd
Annual variation in breeding success among female white-tailed deer (Odocoileus virginianus) fawns on the Savannah River Plant (1967 to 1985) was determined from direct counts of pregnancy in spring-collected fawn females and evidence of lactation and measurements of udder thickness in fall-harvested 1. 5-yearolds. Percent lactation in 1.5-year-old females collected during September and October gave the best estimate of fawn breeding in the previous year. The overall mean fawn breeding estimate from September and October was 41 % , and the yearly variation in fawn breeding was significant. An estimate of the average yearly contribution to recruitment was 43 fetuses per 100 fawn females
Genetic Structure of Mosquitofish Populations in the Altamaha and Ogeechee Drainages of Georgia: Reporting an Undescribed Form in the Ocmulgee River
An electrophoretic survey of genetic variation in mosquitofish populations of the Altamaha and Ogeechee drainages in Georgia revealed significant divergence (fs,=O.270) among populations within the Altamaha. Cluster analysis showed two lineages: one formed by populations from the Ogeechee drainage and the eastern and central Altamaha branches and another consisting of populations from the Ocmulgee River, the westernmost branch of the Altamaha drainage. These lineages may represent two independent forms. Average modified Rogers’ genetic distance was 0.25% between the two groups. The O_cmulgee lineage had significantly higher multilocus heterozygosity (H=0.206) than the other one (I-/=0.120). The high heterozygosity in the Ocmulgee lineage is consistent with the hypothesis that it originated by hybridization. Populations in the Altamaha and Ogeechee exhibit spatial patterns of genetic characteristics similar to those previously described for populations in other drainages
Morphological asymmetry in mammals: genetics and homeostasis reconsidered
It has been hypothesized that developmental stability is increased at higher levels of genetic variability (heterozygosity) in animals. However, the existence of this relationship is questionable for homeotherms in general and mammals in particular. The difference between the sides of a bilateral character in an individual is a measure of fluctuating asymmetry that can be used as a measure of the developmental stability of mammals. Increased developmental stability should result in a greater degree of similarity between the right and left side of the body even though environmental variability would tend to increase the differences between right and left sides of the body. It is necessary to separate the effects of the three types of asymmetry so that an accurate estim.ate of the variance attributable to fluctuating asymmetry can be made. In addition, many early studies of asymmetry in poikilotherms used meristic characters (such as scale counts), and these types of characters are not easily studied in mammals. Mammals, because of their precise regulation of body temperature show little phenotypic effect of environmental variability, and thus may exhibit low absolute levels of asymmetry. Mammals may also be able to reduce the level of asymmetry during their prolonged intrauterine development and juvenile growth period. The literature is reviewed relative to relationships between genetic variation and asymmetry in mammals. Hypotheses are reviewed as they relate to the relationship between fluctuating asymmetry and heterozygosity observed in previous studies. Finally, recommendations are put forth regarding the design and interpretation of future research into the relationship between developmental homeostasis and genetic variability
Genetic Structure of Mosquitofish Populations in the Altamaha and Ogeechee Drainages of Georgia: Reporting an Undescribed Form in the Ocmulgee River
An electrophoretic survey of genetic variation in mosquitofish populations of the Altamaha and Ogeechee drainages in Georgia revealed significant divergence (fs,=O.270) among populations within the Altamaha. Cluster analysis showed two lineages: one formed by populations from the Ogeechee drainage and the eastern and central Altamaha branches and another consisting of populations from the Ocmulgee River, the westernmost branch of the Altamaha drainage. These lineages may represent two independent forms. Average modified Rogers’ genetic distance was 0.25% between the two groups. The O_cmulgee lineage had significantly higher multilocus heterozygosity (H=0.206) than the other one (I-/=0.120). The high heterozygosity in the Ocmulgee lineage is consistent with the hypothesis that it originated by hybridization. Populations in the Altamaha and Ogeechee exhibit spatial patterns of genetic characteristics similar to those previously described for populations in other drainages
Genetic Variation Among Populations of River Otters in North America: Considerations For Reintroducing Projects
Horizontal starch gel electrophoresis was used to assess variability at 23 presumptive gene loci of 732 river otters obtained from fur-trappers in 18 states and three Canadian provinces. States and provinces providing otters were sorted into eight geographic regions for genetic comparisons. Multilocus heterozygosity and polymorphism ranged from 0.018 to 0.032 and 0.044 to 0.087, respectively. One locus, esterase-2, (EST-2) demonstrated a high level of polymorphism throughout all regions. Malate dehydrogenase-1 (MDH-1) was polymorphic throughout the Mississippi drainage but not elsewhere. Heterozygosity, occurrence of rare alleles, and mean number of alleles per locus were associated positively with estimated population sizes. Average heterozygosity and polymorphism values for otters within regions were lower than overall averages reported for mammals but similar to the range of those observed in other mammalian carnivores. Patterns of gene flow suggested by the distribution of polymorphism at the MDH-1 locus do not concur with the current taxonomic classification of river otters. Levels of genetic variation detected in this investigation present a positive outlook for the maintenance of genetic diversity in river otter populations, if sound management principles are applied for reintroductions
The 1.4 GHz Cosmic Star Formation History at z < 1.3
We measure the cosmic star formation history out to z = 1.3 using a sample of
918 radio-selected star forming galaxies within the 2 square degree COSMOS
field. To increase our sample size, we combine 1.4 GHz flux densities from the
VLA-COSMOS catalogue with flux densities measured from the VLA-COSMOS radio
continuum image at the positions of I < 26.5 galaxies, enabling us to detect
1.4 GHz sources as faint as 40 uJy. We find radio measurements of the cosmic
star formation history are highly dependent on sample completeness and models
used to extrapolate the faint end of the radio luminosity function. For our
preferred model of the luminosity function, we find the star formation rate
density increases from 0.019 Solar masses per year per cubic Mpc at z = 0.225
to 0.104 Solar masses per year per cubic Mpc, which agrees to within 33% of
recent UV, IR and 3 GHz measurements of the cosmic star formation history.Comment: 7 pages, 3 figures. Accepted for publication in Publications of the
Astronomical Society of Australi
- …