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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.

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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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Mating ability and offspring production in reciprocal crosses between N2 and CB4856. A single male was crossed with 14 hermaphrodites and was transferred onto a new plate with 14 young hermaphrodites every day for six days. For crosses the hermaphrodite strain is mentioned first and the male strain second. A) Number of successful copulations a male achieved during its life time. B) Total number of cross-progeny produced per male (estimated as twice the number of males). C) Number of cross- (dark color) and self- (light color) progeny produced per successfully mated hermaphrodite after they were separated from the male. Values are the average of five independent replicates. The error bars designate standard errors. Note: C does not include the progeny these hermaphrodites produced during the time they were on the mating plates. For further details see Materials and Methods.
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Figure 2: Mating ability and offspring production in reciprocal crosses between N2 and CB4856. A single male was crossed with 14 hermaphrodites and was transferred onto a new plate with 14 young hermaphrodites every day for six days. For crosses the hermaphrodite strain is mentioned first and the male strain second. A) Number of successful copulations a male achieved during its life time. B) Total number of cross-progeny produced per male (estimated as twice the number of males). C) Number of cross- (dark color) and self- (light color) progeny produced per successfully mated hermaphrodite after they were separated from the male. Values are the average of five independent replicates. The error bars designate standard errors. Note: C does not include the progeny these hermaphrodites produced during the time they were on the mating plates. For further details see Materials and Methods.

Mentions: The factors underlying variation in male maintenance were systematically assessed by reciprocal crosses. The analysis was based on all possible mating combinations between CB4856 and N2, using an incomplete block design (i.e. not all combinations were assayed at the same time; see methods). The main experiment focused on the consequences of repeated mating for individual males, which is likely to be realistic in most populations, where male frequency is usually less than 0.01 [24]. Three parameters were simultaneously evaluated: i) The number of successful copulations per individual male, which was offered an excess of virgin hermaphrodites (14 hermaphrodites) every day over a period of six days, ii) the number of sired offspring per male with – accordingly – virtually unlimited access to mates, and iii) the number of cross- and self-progeny per successfully mated hermaphrodite (for experimental details see Methods). Since early reproduction should have a stronger influence on population dynamics than late reproduction, we also performed a separate analysis of the data from only the first two days (Table 1B). The results lead to essentially identical conclusions like the results for the full reproductive period (Figure 2 and Table 1). Therefore, in the following we focus our discussion on the data for the full reproductive life-span.


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)

Mating ability and offspring production in reciprocal crosses between N2 and CB4856. A single male was crossed with 14 hermaphrodites and was transferred onto a new plate with 14 young hermaphrodites every day for six days. For crosses the hermaphrodite strain is mentioned first and the male strain second. A) Number of successful copulations a male achieved during its life time. B) Total number of cross-progeny produced per male (estimated as twice the number of males). C) Number of cross- (dark color) and self- (light color) progeny produced per successfully mated hermaphrodite after they were separated from the male. Values are the average of five independent replicates. The error bars designate standard errors. Note: C does not include the progeny these hermaphrodites produced during the time they were on the mating plates. For further details see Materials and Methods.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: Mating ability and offspring production in reciprocal crosses between N2 and CB4856. A single male was crossed with 14 hermaphrodites and was transferred onto a new plate with 14 young hermaphrodites every day for six days. For crosses the hermaphrodite strain is mentioned first and the male strain second. A) Number of successful copulations a male achieved during its life time. B) Total number of cross-progeny produced per male (estimated as twice the number of males). C) Number of cross- (dark color) and self- (light color) progeny produced per successfully mated hermaphrodite after they were separated from the male. Values are the average of five independent replicates. The error bars designate standard errors. Note: C does not include the progeny these hermaphrodites produced during the time they were on the mating plates. For further details see Materials and Methods.
Mentions: The factors underlying variation in male maintenance were systematically assessed by reciprocal crosses. The analysis was based on all possible mating combinations between CB4856 and N2, using an incomplete block design (i.e. not all combinations were assayed at the same time; see methods). The main experiment focused on the consequences of repeated mating for individual males, which is likely to be realistic in most populations, where male frequency is usually less than 0.01 [24]. Three parameters were simultaneously evaluated: i) The number of successful copulations per individual male, which was offered an excess of virgin hermaphrodites (14 hermaphrodites) every day over a period of six days, ii) the number of sired offspring per male with – accordingly – virtually unlimited access to mates, and iii) the number of cross- and self-progeny per successfully mated hermaphrodite (for experimental details see Methods). Since early reproduction should have a stronger influence on population dynamics than late reproduction, we also performed a separate analysis of the data from only the first two days (Table 1B). The results lead to essentially identical conclusions like the results for the full reproductive period (Figure 2 and Table 1). Therefore, in the following we focus our discussion on the data for the full reproductive life-span.

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