Density-Dependent Natural Selection in Drosophila: Evolution of Pupation Height

Evolution ◽  
1986 ◽  
Vol 40 (6) ◽  
pp. 1354 ◽  
Author(s):  
Laurence D. Mueller ◽  
Vaughn F. Sweet
Keyword(s):  
Natural Selection ◽  
Density Dependent ◽  
Pupation Height

scholarly journals DENSITY-DEPENDENT NATURAL SELECTION IN DROSOPHILA : EVOLUTION OF PUPATION HEIGHT

Evolution ◽  
1986 ◽  
Vol 40 (6) ◽  
pp. 1354-1356 ◽  
Author(s):  
Laurence D. Mueller ◽  
Vaughn F. Sweet
Keyword(s):  
Natural Selection ◽  
Density Dependent ◽  
Pupation Height

Response of Haemonchus contortus cayugensis to a change in the ratio of smooth to linguiform

Parasitology ◽  
1976 ◽  
Vol 73 (2) ◽  
pp. 213-222 ◽  
Author(s):  
L. F. Le Jambre ◽  
L. H. Ractliffe
Keyword(s):  
Natural Selection ◽  
Population Density ◽  
Seasonal Change ◽  
Negative Correlation ◽  
Haemonchus Contortus ◽  
Stable Equilibrium ◽  
Parasite Population ◽  
Density Dependent ◽  
Positive Correlation

The equilibrium, of vulvar phenotypes in Haemonchus contortus cayugensis was changed by infecting lambs with either a selected strain of smooth or of linguiform worms. Subsequently the lambs grazed the same pasture and observations were made on changes in worm populations in the lambs, and on pasture it appeared that the seasonal change in the relative frequencies of A and B linguiform worms was related to density-dependent factors in the host. In the spring, when lambs first become infected, the worm population is small and the majority of linguiform worms are A-type. As the season progresses the density of the parasite population increases. Once the population becomes crowded selection begins to favour the B-type females. The effects of crowding on linguiform A females can be seen as a positive correlation between the percentage of linguiform A and their weight. Population density also affected the survival of A-type worms since there was a negative correlation of percentage A-type on total worm numbers. There was a similar negative correlation between percentage A-type and total worm numbers in both the continuously infected and tracer lambs.Population density did not affect the proportion of smooth worms. However, smooth worms increased in the tracers from, approximately 10% at the beginning of the experiment to 55% at its conclusion 18 weeks later. The latter percentage is almost within range of the local subspecies, which has 60% or more smooth worms. It appears therefore that the proportion of smooth to linguiform worms is a stable equilibrium maintained by natural selection.

Density-dependent natural selection

1989 ◽  
Vol 4 (4) ◽  
pp. 95-96 ◽  
Author(s):  
Mark A. Elgar ◽  
Carla P. Catterall
Keyword(s):  
Natural Selection ◽  
Density Dependent

Density-Dependent Natural Selection

Ecology ◽  
1971 ◽  
Vol 52 (3) ◽  
pp. 453-468 ◽  
Author(s):  
Jonathan Roughgarden
Keyword(s):  
Natural Selection ◽  
Density Dependent
Sign in / Sign up

Export Citation Format

Share Document