Demographic correlates of sexual size dimorphism and male genital size in the lice philopterus coarctatus

Piotr Tryjanowski, Zbigniew Adamski, Magdalena Dylewska, Lajos Bulkai, L. Rózsa

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Sexual selection is an influential agent of evolution, often shaping the sex ratio, sexual size dimorphism (SSD), and genital size in animals. To explore its effects in ectoparasites, we quantified SSD and male genital size in relation to intensity and sex ratio across subpopulations of Philopterus coarctatus, a philopterid louse of the great grey shrike. SSD was calculated separately for the width and length of the head and abdomen. Presuming that sexual selection affects the evolution of avian lice, we would expect that infestation intensities should covary with sex ratio, relative male size, and relative male genital size, either positively or negatively depending upon presumptions. Contrary to former studies, there was a weak negative relationship between infestation intensity and sex ratio. The relative width of male abdomens exhibited a highly significant negative interaction with the intensity of infestations. In contrast, sex ratio did not predict any of the dimorphism measures. Similarly, male genital size did not covary with the intensity of infestations or sex ratios. These findings may indicate that intensity covaries positively with levels of inbreeding in this species, suggesting that more-inbred subpopulations, wasting less energy for sexual rivalry, can multiply more intensively. Thus, small subpopulations have more frequent males which also possess larger abdomens. Alternatively, however, the same pattern may also arise due to male-biased starvation in overcrowded habitats; thus, males are rarer and have smaller abdomens in larger infrapopulations.

Original languageEnglish
Pages (from-to)1120-1124
Number of pages5
JournalJournal of Parasitology
Volume95
Issue number5
DOIs
Publication statusPublished - Oct 2009

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Phthiraptera
louse
lice
dimorphism
male genitalia
Sex Characteristics
sex ratio
Sex Ratio
demographic statistics
Demography
abdomen
Abdomen
subpopulation
sexual selection
ectoparasites
inbreeding
genitalia
ectoparasite
starvation
Inbreeding

ASJC Scopus subject areas

  • Parasitology
  • Ecology, Evolution, Behavior and Systematics

Cite this

Demographic correlates of sexual size dimorphism and male genital size in the lice philopterus coarctatus. / Tryjanowski, Piotr; Adamski, Zbigniew; Dylewska, Magdalena; Bulkai, Lajos; Rózsa, L.

In: Journal of Parasitology, Vol. 95, No. 5, 10.2009, p. 1120-1124.

Research output: Contribution to journalArticle

Tryjanowski, Piotr ; Adamski, Zbigniew ; Dylewska, Magdalena ; Bulkai, Lajos ; Rózsa, L. / Demographic correlates of sexual size dimorphism and male genital size in the lice philopterus coarctatus. In: Journal of Parasitology. 2009 ; Vol. 95, No. 5. pp. 1120-1124.
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