Persistent Copulation in Asexual Female   Potamopyrgus antipodarum: Evidence for Male Control with Size-Based Preferences

Table 1

Copulation frequency, shell length, and lineage age in asexual cultures.

Culture	Mean copulation frequency ± 1 SD	Mean shell length ± 1 SD	Lineage age	𝑁
Taylora,b	0.13 ± 0.13	4.27 ± 0.33	YOUNG	14
Mapourikaa	0.13 ± 0.18	4.32 ± 0.31	OLD	13
Denmark A∗	0.15 ± 0.10	4.30 ± 0.24	OLD	5
Duluth∗	0.16 ± 0.37	4.70 ± 0.22	OLD	4
Okarekaa,b	0.18 ± 0.11	4.37 ± 0.58	OLD	15
Saraha	0.19 ± 0.15	4.54 ± 0.50	YOUNG	14
Poerua	0.24 ± 0.15	4.53 ± 0.21	YOUNG	14
Waikaremoana Lab∗∗	0.25 ± 0.15	4.65 ± 0.47	OLD∗∗	19
Evelyn	0.31 ± 0.16	4.67 ± 0.32	YOUNG	13
Waikaremoana Field∗∗	0.32 ± 0.15	4.65 ± 0.42	OLD∗∗	19
Tarawerac	0.35 ± 0.15	5.09 ± 0.82	OLD	14
Taupoc	0.39 ± 0.21	5.60 ± 0.61	OLD	15
All females	0.25 ± 0.17	4.67 ± 0.59	—	159

Culture of origin (rank ordered by increasing copulation frequency), mean copulation frequency ± SD, mean shell length ± SD, lineage age, and number of individual asexual females used from each culture. “Young” indicates lineages derived from sexual ancestors <70,000 years ago, while “old” indicates lineages derived >500,000 years ago [23]. ∗Denotes the only two population names that do not refer to lakes of origin in New Zealand; the ancestor of the Denmark A lineage was collected in Denmark in the early 1990s, and the ancestor of the Duluth lineage was collected in 2007 in Minnesota, USA from Lake Superior. ∗∗Waikaremoana populations consist of multiple lineages of old asexuals. aDenotes cultures that differed significantly from Taupo in mean copulation frequency via Bonferroni-corrected chi-square comparisons. bDenotes significant differences in copulation frequency from Tarawera. cTaupo differed significantly in mean length from all cultures except Tarawera (𝑡-tests). All differences are significant at 𝑃<.05.