TY - JOUR

T1 - Sperm competition intensity affects sperm precedence patterns in a polyandrous gift-giving spider

AU - Matzke, Magdalena

AU - Toft, Søren

AU - Bechsgaard, Jesper

AU - Pold Vilstrup, Astrid

AU - Uhl, Gabriele

AU - Künzel, Sven

AU - Tuni, Cristina

AU - Bilde, Trine

N1 - Publisher Copyright: © 2022 The Authors. Molecular Ecology published by John Wiley & Sons Ltd.

PY - 2022/4

Y1 - 2022/4

N2 - Sperm competition drives traits that enhance fertilization success. The amount of sperm transferred relative to competitors is key for attaining paternity. Female reproductive morphology and male mating order may also influence fertilization, however the outcome for sperm precedence under intense sperm competition remains poorly understood. In the polyandrous spider Pisaura mirabilis, males offer nuptial gifts which prolong copulation and increase sperm transfer, factors proposed to alter sperm precedence patterns under strong sperm competition. First, we assessed the degree of female polyandry by genotyping wild broods. A conservative analysis identified up to four sires, with a mean of two sires per brood, consistent with an optimal mating female rate. Then we asked whether intense sperm competition shifts sperm precedence patterns from first male priority, as expected from female morphology, to last male advantage. We varied sexual selection intensity experimentally and determined competitive fertilization outcome by genotyping broods. In double matings, one male monopolised paternity regardless of mating order. A mating order effect with first male priority was revealed when females were mated to four males, however this effect disappeared when females were mated to six males, probably due to increased sperm mixing. The proportion of males that successfully sired offspring drastically decreased with the number of competitors. Longer copulations translated into higher paternity shares independently of mating order, reinforcing the advantage of traits that prolong copulation duration under intense competition, such as the nuptial gift. Sperm competition intensity enhances the impact of competitive sexual traits and imposes multiple effects on paternity.

AB - Sperm competition drives traits that enhance fertilization success. The amount of sperm transferred relative to competitors is key for attaining paternity. Female reproductive morphology and male mating order may also influence fertilization, however the outcome for sperm precedence under intense sperm competition remains poorly understood. In the polyandrous spider Pisaura mirabilis, males offer nuptial gifts which prolong copulation and increase sperm transfer, factors proposed to alter sperm precedence patterns under strong sperm competition. First, we assessed the degree of female polyandry by genotyping wild broods. A conservative analysis identified up to four sires, with a mean of two sires per brood, consistent with an optimal mating female rate. Then we asked whether intense sperm competition shifts sperm precedence patterns from first male priority, as expected from female morphology, to last male advantage. We varied sexual selection intensity experimentally and determined competitive fertilization outcome by genotyping broods. In double matings, one male monopolised paternity regardless of mating order. A mating order effect with first male priority was revealed when females were mated to four males, however this effect disappeared when females were mated to six males, probably due to increased sperm mixing. The proportion of males that successfully sired offspring drastically decreased with the number of competitors. Longer copulations translated into higher paternity shares independently of mating order, reinforcing the advantage of traits that prolong copulation duration under intense competition, such as the nuptial gift. Sperm competition intensity enhances the impact of competitive sexual traits and imposes multiple effects on paternity.

KW - copulation duration

KW - fertilization outcome

KW - mating order

KW - microsatellite markers

KW - paternity

KW - sperm competition

KW - sperm precedence

U2 - 10.1111/mec.16405

DO - 10.1111/mec.16405

M3 - Journal article

C2 - 35178803

AN - SCOPUS:85125543693

VL - 31

SP - 2435

EP - 2452

JO - Molecular Ecology

JF - Molecular Ecology

SN - 0962-1083

IS - 8

ER -