Genetic variation among trait groups and apparent absence of close inbreeding in grey-crowned babblers

1980 ◽  
Vol 7 (2) ◽  
pp. 93-98 ◽  
Author(s):  
M. S. Johnson ◽  
J. L. Brown
Keyword(s):  
Genetic Variation ◽  
Apparent Absence ◽  
Close Inbreeding ◽  
Trait Groups

Asynchronous maturation of the sexes may limit close inbreeding in a subsocial spider

2002 ◽  
Vol 80 (2) ◽  
pp. 193-198 ◽  
Author(s):  
Todd C Bukowski ◽  
Leticia Avilés
Keyword(s):  
Life Cycle ◽  
Temporal Patterns ◽  
Significant Fraction ◽  
Sexual Receptivity ◽  
Mating Season ◽  
Apparent Absence ◽  
Males And Females ◽  
Final Molt ◽  
Asynchronous Maturation ◽  
Close Inbreeding

We studied the temporal patterns of maturation and sexual receptivity of a subsocial spider, Anelosimus cf. jucundus, in southern Arizona. In subsocial spiders, sibling males and females share a common nest for a large portion of their life cycle, often only dispersing short distances close to the mating season. We found that, on average, male A. cf. jucundus matured 9 days earlier than females and that females did not become sexually receptive until 10 days following their final molt to maturity. The periods of sexual receptivity of sibling males and females, therefore, would be separated in time by a significant fraction of an adult male's life cycle. We also found significant asynchrony in maturation dates across nests and nest clusters at the two collection localities. We suggest that these temporal patterns may limit the opportunities for sibling males and females to mate with each other, thus explaining the apparent absence of mechanisms to discriminate against kin as mates in this species.

Apparent absence of genetic differences among species of Teladorsagia (Nematoda: Trichostrongylidae)

1990 ◽  
Vol 64 (4) ◽  
pp. 290-294 ◽  
Author(s):  
R. H. Andrews ◽  
I. Beveridge
Keyword(s):  
Genetic Variation ◽  
Genetic Data ◽  
Single Species ◽  
Genetic Differences ◽  
Morphological Evidence ◽  
Allozyme Electrophoresis ◽  
Apparent Absence ◽  
Enzyme Loci ◽  
Data Support ◽  
Allelic Differences

ABSTRACTThe technique of allozyme electrophoresis was applied to three species of Teladorsagia present in sheep to determine the extent of genetic variation among species. Thirty-four enzyme loci were established of which 22 were invariant and 12 were shown to be polymorphic. No fixed allelic differences were detected among the species and the level of polymorphism was within the range found commonly between populations of a single species. Therefore, the genetic data support breeding data and existing morphological evidence that T. circumcincta, T. davtiani and T. trifurcata as currently recognized do in fact belong to a single species.

Rediscovery of pycnidia in Thamnolia vermicularis: implications for chemotype occurrence and distribution

2013 ◽  
Vol 45 (3) ◽  
pp. 397-411 ◽  
Author(s):  
Janice M. LORD ◽  
Allison KNIGHT ◽  
Jennifer M. BANNISTER ◽  
Lars R. LUDWIG ◽  
William M. MALCOLM ◽  
...  
Keyword(s):  
Genetic Variation ◽  
English Language ◽  
Its Region ◽  
Local Scale ◽  
Long Distance Dispersal ◽  
Long Distance ◽  
Apparent Absence ◽  
Reproductive Structures ◽  
Low Levels ◽  
The 19Th Century

AbstractThamnolia vermicularis is a globally widespread arctic-alpine lichen with two distinct chemotypes. The intermixing of these chemotypes at the local scale and lack of genetic variation between them is puzzling given the apparent absence of specialized reproductive structures. Apothecia and conidiomata were originally reported for Thamnolia in the second half of the 19th century, but putative apothecia proved to be parasitic in origin. This study presents conclusive microscopic evidence for the existence of pycnidial conidiomata containing conidia on thalli of Thamnolia vermicularis from geographically widespread locations. Sequences of the internal transcribed spacer (ITS) region of ribosomal DNA from excised pycnidial conidiomata matched that of thallus tips from individual Thamnolia thalli. Our examination of the historic literature found that the occurrence of pycnidial conidiomata was never disproved, but this information was lost from the post-1920s English-language literature. Our rediscovery of pycnidial conidiomata indicates that Thamnolia vermicularis possesses a reproductive strategy with the potential for long-distance dispersal of multitudes of mitotically produced conidia, providing a plausible explanation for the cosmopolitan distribution of the species and the low levels of genetic variation among populations. Reversible processes, for example alternative splicing, warrant consideration as explanations for chemotype intermixing.

Genetic variation in the human interleukin 4 (IL4) gene is associated with gallstone susceptibility

2011 ◽  
Vol 49 (01) ◽  
Author(s):  
A Tönjes ◽  
A Tönjes ◽  
T Strauch ◽  
C Ruffert ◽  
J Mössner ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Interleukin 4
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