Relative Competitive Success of Unequal Competitors Changes with Overall Density

Oikos ◽  
1996 ◽  
Vol 77 (1) ◽  
pp. 158 ◽  
Author(s):  
Tom Tregenza ◽  
Mace A. Hack ◽  
David J. Thompson
Keyword(s):  
Unequal Competitors ◽  
Competitive Success

scholarly journals Female Genotypes Affect Sperm Displacement in Drosophila

Genetics ◽  
1998 ◽  
Vol 149 (3) ◽  
pp. 1487-1493 ◽  
Author(s):  
Andrew G Clark ◽  
David J Begun
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Natural Populations ◽  
Isogenic Line ◽  
Female Fitness ◽  
Sperm Displacement ◽  
Extensive Variation ◽  
Polymorphic Genes ◽  
Displacement Parameter ◽  
Competitive Success

Abstract Differential success of sperm is likely to be an important component of fitness. Extensive variation among male genotypes in competitive success of sperm in multiply mated females has been documented for Drosophila melanogaster. However, virtually all previous studies considered the female to be a passive vessel. Nevertheless, under certain conditions female fitness could be determined by her role in mediating use of sperm from multiple males. Here we ask whether females differ among genotypes in their tendency to exhibit last-male precedence. Competition of sperm from two tester male genotypes (bwD and B3-09, a third-chromosome isogenic line from Beltsville, MD) was quantified by doubly mating female lines that had been rendered homozygous for X, second, or third chromosomes isolated from natural populations. The composite sperm displacement parameter, P2′, was highly heterogeneous among lines, whether or not viability effects were compensated, implying the presence of polymorphic genes affecting access of sperm to eggs. Genetic variation of this type is completely neutral in the absence of pleiotropy or interaction between variation in the two sexes.

scholarly journals Expression of Mst89B and CG31287 is Needed for Effective Sperm Storage and Egg Fertilization in Drosophila

Cells ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 289
Author(s):  
Gurman Grewal ◽  
Bahar Patlar ◽  
Alberto Civetta
Keyword(s):  
Germ Line ◽  
Sperm Storage ◽  
Mature Sperm ◽  
Sperm Production ◽  
Cytogenetic Map ◽  
Egg Hatchability ◽  
Storage Organs ◽  
Competitive Success ◽  
Paternity Success ◽  
And Storage

In Drosophila, male reproductive fitness can be affected by any number of processes, ranging from development of gametes, transfer to and storage of mature sperm within the female sperm storage organs, and utilization of sperm for fertilization. We have previously identified the 89B cytogenetic map position of D. melanogaster as a hub for genes that effect male paternity success when disturbed. Here, we used RNA interference to test 11 genes that are highly expressed in the testes and located within the 89B region for their role in sperm competition and male fecundity when their expression is perturbed. Testes-specific knockdown (KD) of bor and CSN5 resulted in complete sterility, whereas KD of CG31287, Manf and Mst89B, showed a breakdown in sperm competitive success when second to mate (P2 < 0.5) and reduced fecundity in single matings. The low fecundity of Manf KD is explained by a significant reduction in the amount of mature sperm produced. KD of Mst89B and CG31287 does not affect sperm production, sperm transfer into the female bursa or storage within 30 min after mating. Instead, a significant reduction of sperm in female storage is observed 24 h after mating. Egg hatchability 24 h after mating is also drastically reduced for females mated to Mst89B or CG31287 KD males, and this reduction parallels the decrease in fecundity. We show that normal germ-line expression of Mst89B and CG31287 is needed for effective sperm usage and egg fertilization.

The effects of phosphorus and temperature on the competitive success of an invasive cyanobacterium

2017 ◽  
Vol 51 (3) ◽  
pp. 463-472 ◽  
Author(s):  
Caitlin N. Ryan ◽  
Mridul K. Thomas ◽  
Elena Litchman
Keyword(s):  
Competitive Success

Process integration for competitive success

2001 ◽  
Vol 8 (5) ◽  
pp. 396-412 ◽  
Author(s):  
Stanley E. Fawcett ◽  
M. Bixby Cooper
Keyword(s):  
Process Integration ◽  
Competitive Success

scholarly journals WITHIN-HOST COMPETITION IN GENETICALLY DIVERSE MALARIA INFECTIONS: PARASITE VIRULENCE AND COMPETITIVE SUCCESS

Evolution ◽  
2006 ◽  
Vol 60 (7) ◽  
pp. 1358-1371 ◽  
Author(s):  
Andrew S. Bell ◽  
Jacobus C. Roode ◽  
Derek Sim ◽  
Andrew F. Read
Keyword(s):  
Competitive Success

People, capability and competitive success

1995 ◽  
Vol 8 (5) ◽  
pp. 6-10 ◽  
Author(s):  
Jeffrey Pfeffer
Keyword(s):  
Competitive Success

scholarly journals Mapping logistics practice using the product life cycle

1999 ◽  
Vol 11 (1) ◽  
pp. 1-22
Author(s):  
Stanley E Fawcett ◽  
Greg Magnan ◽  
Laura Birou
Keyword(s):  
Life Cycle ◽  
Global Economy ◽  
Product Life Cycle ◽  
Planning Process ◽  
Product Life ◽  
Logistics Strategy ◽  
Competitive Success ◽  
Strategy Planning ◽  
Implementation Status

The dynamic nature of today's global economy places a premium on a firm's ability to anticipate and to respond to customer needs as well as changing competitive pressures. Within this environment, developing a successful logistics strategy can be critical to the firm's long-term competitive success. This paper looks at the potential for using the product life cycle (PLC) as a strategic framework in the logistics strategy planning process. Results of an empirical study that investigated the appropriate use of 43 logistics techniques across PLC stages are reported. The implementation status of the various logistics techniques is also considered.

Sign in / Sign up

Export Citation Format

Share Document