Figure 1.
The hypothesized effect of increasing seawater temperatures on the worm pipefish breeding season length and potential consequences in terms of sexual selection pressure.
Shorter breeding seasons should imply less available males, as most will become pregnant rapidly, causing a female biased OSR that, in turn, should influence the degree of female-female competition and investment in reproduction. Increased competition and investment should further reduce the number of still available males, as in a positive feedback loop. As a result, sexual selection pressure is expected to increase, a pattern that may be reflected in the degree of sexual dimorphism.
Figure 2.
The biogeographical distribution of Nerophis lumbriciformis, according to Dawson (1986).
Circles indicate the location of the two sampled populations (P = Portugal, Viana do Castelo, 41°70′N 8°85′W; I = Ireland, Galway Bay, 53°15' N 9°10′W). Pictures of adult worm pipefish are also presented (A- Male's facial pigmentation; B- Male's empty brooding surface; C- Male's brooding surface with eggs; D- Female's facial pigmentation; E- Female′s keel-like structure on the abdominal region).
Figure 3.
The surface seawater temperatures in the sampled areas is presented in the top plots, highlighting the average (dotted line) as well as the highest and lowest temperature values.
The second and third plot rows depict the monthly average size of sexually mature female and male worm pipefish, respectively, with bars indicating the maximum and minimum values. The filled areas in the background show the monthly percentages of large, intermediate, and small individuals. The bottom plots represent the monthly variation in sex ratios (full circles depict the sex ratio while open circles show the operational sex ratio). Values for the Irish population are presented in the left column while those from the Portuguese population are shown in the right column.
Figure 4.
The monthly percentage of Nerophis lumbriciformis pregnant males in Ireland (left column) and Portugal (right column), where the filled areas depict the relative contribution of either large, intermediate or small individuals (top row).
Middle row plots show the monthly average number of eggs carried in large, intermediate or small male's incubating surface. Bottom row plots illustrate the monthly average number of oocytes in large, intermediate and small Irish females.
Figure 5.
The annual percentage of pregnant males according to size class (left plot) and the average brooding surface area (right plot), in Ireland (light grey) and Portugal (dark grey; “miss.” indicates missing values).