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Experimental insight into the proximate causes of male persistence variation among two strains of the androdioecious Caenorhabditis elegans (Nematoda).

Wegewitz V, Schulenburg H, Streit A - BMC Ecol. (2008)

Bottom Line: This is not the case in some other wild type isolates of C. elegans, among them the Hawaiian strain CB4856.We determined the kinetics of the loss of males over time for multiple population sizes and wild isolates and found significant differences.In particular, CB4856 males obtained a higher number of successful copulations than N2 males and sired correspondingly more cross-progeny.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Evolutionary Biology, Max Planck Institute for Developmental Biology, Tübingen, Germany. viktoria.wegewitz@tuebingen.mpg.de

ABSTRACT

Background: In the androdioecious nematode Caenorhabditis elegans virtually all progeny produced by hermaphrodite self-fertilization is hermaphrodite while 50% of the progeny that results from cross-fertilization by a male is male. In the standard laboratory wild type strain N2 males disappear rapidly from populations. This is not the case in some other wild type isolates of C. elegans, among them the Hawaiian strain CB4856.

Results: We determined the kinetics of the loss of males over time for multiple population sizes and wild isolates and found significant differences. We performed systematic inter- and intra-strain crosses with N2 and CB4856 and show that the males and the hermaphrodites contribute to the difference in male maintenance between these two strains. In particular, CB4856 males obtained a higher number of successful copulations than N2 males and sired correspondingly more cross-progeny. On the other hand, N2 hermaphrodites produced a higher number of self-progeny, both when singly mated and when not mated.

Conclusion: These two differences have the potential to explain the observed variation in male persistence, since they should lead to a predominance of self-progeny (and thus hermaphrodites) in N2 and, at the same time, a high proportion of cross-progeny (and thus the presence of males as well as hermaphrodites) in CB4856.

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Number of contacts and spicule insertions observed over 14 observation points within 9 hours. Mating assays with one male and 14 hermaphrodites were set up for CB4856 and N2, using 45 and 47 replicates, respectively. The plates were inspected 14 times within the first 9 hours. The figure shows the average number of male-hermaphrodite contacts and spicule insertions. Each spicule insertion was also considered to be a contact. The error bars designate standard errors. For exact numbers and statistical analysis [see additional file 5].
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Figure 3: Number of contacts and spicule insertions observed over 14 observation points within 9 hours. Mating assays with one male and 14 hermaphrodites were set up for CB4856 and N2, using 45 and 47 replicates, respectively. The plates were inspected 14 times within the first 9 hours. The figure shows the average number of male-hermaphrodite contacts and spicule insertions. Each spicule insertion was also considered to be a contact. The error bars designate standard errors. For exact numbers and statistical analysis [see additional file 5].

Mentions: However, over 14 observation points within the first 9 hours, the CB4856 × CB4856 crosses produced significantly more male-hermaphrodite contacts (Fig. 3 and [see Additional file 5]; Wilcoxon test, Z = 6.59, N = 45 for CB4856, N = 47 for N2, P < 0.001) and spicule insertions (Fig. 3 and [see Additional file 5]; Wilcoxon test, Z = 2.98, N = 45 for CB4856, N = 47 for N2, P = 0.003). From these observations, we conclude that over time CB4856 males achieve a higher rate of mate contacts and spicule insertions than N2 males. These results are in excellent agreement with the results presented in Fig. 2 and Table 1. Consequently, an overall higher mating frequency could contribute to the observed higher male persistence in CB4856 relative to N2. We cannot explain why N2 males mate less frequently than CB4856. One possibility would be that N2 males require a longer time to replenish their sperm stocks. If so, they could produce a smaller number of sperm over their life time which would explain the reduced number of progeny sired.


Experimental insight into the proximate causes of male persistence variation among two strains of the androdioecious Caenorhabditis elegans (Nematoda).

Wegewitz V, Schulenburg H, Streit A - BMC Ecol. (2008)

Number of contacts and spicule insertions observed over 14 observation points within 9 hours. Mating assays with one male and 14 hermaphrodites were set up for CB4856 and N2, using 45 and 47 replicates, respectively. The plates were inspected 14 times within the first 9 hours. The figure shows the average number of male-hermaphrodite contacts and spicule insertions. Each spicule insertion was also considered to be a contact. The error bars designate standard errors. For exact numbers and statistical analysis [see additional file 5].
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2483263&req=5

Figure 3: Number of contacts and spicule insertions observed over 14 observation points within 9 hours. Mating assays with one male and 14 hermaphrodites were set up for CB4856 and N2, using 45 and 47 replicates, respectively. The plates were inspected 14 times within the first 9 hours. The figure shows the average number of male-hermaphrodite contacts and spicule insertions. Each spicule insertion was also considered to be a contact. The error bars designate standard errors. For exact numbers and statistical analysis [see additional file 5].
Mentions: However, over 14 observation points within the first 9 hours, the CB4856 × CB4856 crosses produced significantly more male-hermaphrodite contacts (Fig. 3 and [see Additional file 5]; Wilcoxon test, Z = 6.59, N = 45 for CB4856, N = 47 for N2, P < 0.001) and spicule insertions (Fig. 3 and [see Additional file 5]; Wilcoxon test, Z = 2.98, N = 45 for CB4856, N = 47 for N2, P = 0.003). From these observations, we conclude that over time CB4856 males achieve a higher rate of mate contacts and spicule insertions than N2 males. These results are in excellent agreement with the results presented in Fig. 2 and Table 1. Consequently, an overall higher mating frequency could contribute to the observed higher male persistence in CB4856 relative to N2. We cannot explain why N2 males mate less frequently than CB4856. One possibility would be that N2 males require a longer time to replenish their sperm stocks. If so, they could produce a smaller number of sperm over their life time which would explain the reduced number of progeny sired.

Bottom Line: This is not the case in some other wild type isolates of C. elegans, among them the Hawaiian strain CB4856.We determined the kinetics of the loss of males over time for multiple population sizes and wild isolates and found significant differences.In particular, CB4856 males obtained a higher number of successful copulations than N2 males and sired correspondingly more cross-progeny.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Evolutionary Biology, Max Planck Institute for Developmental Biology, Tübingen, Germany. viktoria.wegewitz@tuebingen.mpg.de

ABSTRACT

Background: In the androdioecious nematode Caenorhabditis elegans virtually all progeny produced by hermaphrodite self-fertilization is hermaphrodite while 50% of the progeny that results from cross-fertilization by a male is male. In the standard laboratory wild type strain N2 males disappear rapidly from populations. This is not the case in some other wild type isolates of C. elegans, among them the Hawaiian strain CB4856.

Results: We determined the kinetics of the loss of males over time for multiple population sizes and wild isolates and found significant differences. We performed systematic inter- and intra-strain crosses with N2 and CB4856 and show that the males and the hermaphrodites contribute to the difference in male maintenance between these two strains. In particular, CB4856 males obtained a higher number of successful copulations than N2 males and sired correspondingly more cross-progeny. On the other hand, N2 hermaphrodites produced a higher number of self-progeny, both when singly mated and when not mated.

Conclusion: These two differences have the potential to explain the observed variation in male persistence, since they should lead to a predominance of self-progeny (and thus hermaphrodites) in N2 and, at the same time, a high proportion of cross-progeny (and thus the presence of males as well as hermaphrodites) in CB4856.

Show MeSH
Related in: MedlinePlus