Mating Order Establishes Male Size Advantage in the Polygynandrous Millipede Centrobolus inscriptus Attems, 1928 | Chapter 7 | New Visions in Biological Science Vol.9

 The size assortative mating of a forest species of millipede belonging to the Order Spirobolida found along the eastern coast of southern Africa was investigated. The goals are to test for size benefits in mating by controlling for SSD in multiple mating. The duration of the first mating was positively related to male length (rs=0.30, n=46, P=0.04), but inversely connected to the duration of the second mating (rs=-0.35, n=46, P=0.02). When female width (z=-0.59, n=46, 46, p=0.60) and SSD (z=-1.08, n=46, 46, p=0.28) were adjusted, male length and copulation duration were different in first and second matings (z=3.13, n=46, 46, p0.01). Female choice based on male lengths explained a mating order effect from positive to negative size advantage in mating.

Author(s) Details:

Mark Cooper,
School of Animal, Plant & Environmental Sciences University of the Witwatersrand, Johannesburg 2050, South Africa.

Please see the link here: https://stm.bookpi.org/NVBS-V9/article/view/5871

Length and Width Correlations in Centrobolus Cook, 1897| Chapter 6 | New Visions in Biological Science Vol.9

 The size correlations of a forest genus of diplopods belonging to the order Spirobolida found along the eastern coast of southern Africa were investigated. The Pearson Correlation Coefficient Calculator was used to assess for correlations between four morphometric parameters for male and female lengths (mm) and widths (mm) collected from literature. In a study of 22 Centrobolus species, positive relationships were discovered. Male and female lengths and widths were shown to have strong positive connections. Female length and male width had a moderately favourable connection (r=0.72, Z score=3.91, n=22, p0.01). Male length and female width had a positive connection (r=0.62, Z score=3.16, n=22, p0.01). Male length/female width correlation (z=1.93, n=22, 22, p=0.05) differed from male length/female width correlation.

Author(s) Details:

Mark Cooper,
School of Animal, Plant & Environmental Sciences University of the Witwatersrand, Johannesburg 2050, South Africa.

Please see the link here: https://stm.bookpi.org/NVBS-V9/article/view/5869

Copulation duration Allometry in Worm-like Millipedes (Diplopoda: Chilognatha: Helminthomorpha) | Chapter 5 | New Visions in Biological Science Vol.9

 Copulation duration variance in mate-guarding worm-like millipedes was examined as one of many determining factors of copulation duration across arthropods. In worm-like millipedes, the goal was to compute copulation duration allometry. The null hypothesis was that mean copulation duration and variance were unaffected by body mass. The length of copulation and the standard deviation squared for 20 millipede populations were taken from the literature. The length of copulation was highly associated to variation (r=0.87, Z score= 5.74, n=21, p0.01). These included forest species such as Gigantowales chisholmi (0.09) and Alloporus uncinatus (Mazowe-Hwange) (4238.01). (C. anulatus, C. inscriptus, C. ruber). Female mass (r=0.68, Z score=2.89, n=15, p0.01) was shown to be linked with copulation duration variance (r=0.68, Z score=2.89, n=15, p0.01). Male mass (r=0.80, Z score=3.85, n=15, p0.01) was shown to be linked with copulation length variance (r=0.80, Z score=3.85, n=15, p0.01). These relationships were not significantly different (z=-0.67, n=15, 15, p=0.50). Male mass was only slightly linked with copulation duration (r=0.40, Z score=1.55, n=16, p=0.06). Female mass was not associated to copulation duration (r=0.33, Z score=1.22, n=16, p=0.11). These correlation coefficients were identical (z=0.23, n=16, 16, p=0.82). When intraspecific variation in copulation length was controlled, it was shown that it was negatively related to size and connected with the severity of sperm competition (equal). The duration of copulation is controlled by males based on the mass and intensity of sperm competition.

Author(s) Details:

Mark Cooper,
School of Animal, Plant & Environmental Sciences University of the Witwatersrand, Johannesburg 2050, South Africa.

Please see the link here: https://stm.bookpi.org/NVBS-V9/article/view/5867

The Copulation duration Allometry in Centrobolus (Diplopoda: Spirobolida: Pachybolidae)| Chapter 4 | New Visions in Biological Science Vol.9

 Copulation duration variance in forest millipedes was examined as one of the deciding elements of copulation duration across arthropods. The goal was to figure out how much variance there was in copulation time. The null hypothesis was that mean copulation duration and variance were unaffected by body mass. In the literature, copulation duration and standard deviation squared for four millipede populations were found. Copulation duration and variance were associated (r=0.95, r2=0.90, n=5, p=0.01). C. anulatus had the shortest duration (34.9 minutes) and C. inscriptus had the longest (303 minutes) The variance in copulation length was linked with female mass (r=0.95, z-score=1.86, n=4, p=0.03). Millipedes, like several arachnids, had a correlation between copulation duration and variance in copulation duration and intra-specific size variation. Female mass and copulation time were associated (r=0.99, z-score=2.71, n=4, p0.01). Male mass was associated to sexual size dimorphism (r=-0.97, z-score=-2.17, n=4, p=0.01). Longer copulation duration was thought to be connected to sperm competition intensity and female control of copulation duration. Females regulate the length of copulation dependent on their bulk.

Author(s) Details:

Mark Cooper,
School of Animal, Plant & Environmental Sciences University of the Witwatersrand, Johannesburg 2050, South Africa.

Please see the link here: https://stm.bookpi.org/NVBS-V9/article/view/5866