TY - JOUR
T1 - Evolution of large males is associated with female-skewed adult sex ratios in amniotes
AU - Liker, András
AU - Bókony, Veronika
AU - Pipoly, Ivett
AU - Lemaître, Jean Francois
AU - Gaillard, Jean Michel
AU - Székely, Tamás
AU - Freckleton, Robert P.
N1 - Funding Information:
We thank D. Gigler, G. Milne, H. Naylor, and E. Sebestyén for help in data collection; Z. Végvári for calculating environmental variables; and B. Vági for discussions. AL was supported by the National Research, Development and Innovation Office of Hungary (NKFIH, grants KH130430 and K132490), by the Hungarian Academy of Sciences, and by the TKP2020‐IKA‐07 project financed under the 2020–4.1.1‐TKP2020 Thematic Excellence Program by the National Research, Development and Innovation Fund of Hungary. IP was supported by the ÚNKP‐17‐3 New National Excellence Program of the Ministry of Human Capacities. VB was supported by an NKFIH grant (K115402), the János Bolyai Scholarship of the Hungarian Academy of Sciences, and the ÚNKP‐20‐5 New National Excellence Program of the Ministry for Innovation and Technology from the source of the National Research, Development and Innovation Fund. J‐FL and J‐MG were supported by a grant from the Agence Nationale de la Recherche (ANR‐15‐CE32‐0002‐01). TS and AL were supported by an NKFIH grant (K116310). TS is funded by a Royal Society Wolfson Merit award and by ÉLVONAL KKP‐126949. TS and J‐MG were supported by a grant of the Royal Society‐CNRS (IE160592).
PY - 2021/7/19
Y1 - 2021/7/19
N2 - Body size often differs between the sexes (leading to sexual size dimorphism, SSD), as a consequence of differential responses by males and females to selection pressures. Adult sex ratio (ASR, the proportion of males in the adult population) should influence SSD because ASR relates to both the number of competitors and available mates, which shape the intensity of mating competition and thereby promotes SSD evolution. However, whether ASR correlates with SSD variation among species has not been yet tested across a broad range of taxa. Using phylogenetic comparative analyses of 462 amniotes (i.e., reptiles, birds, and mammals), we fill this knowledge gap by showing that male bias in SSD increases with increasingly female-skewed ASRs in both mammals and birds. This relationship is not explained by the higher mortality of the larger sex because SSD is not associated with sex differences in either juvenile or adult mortality. Phylogenetic path analysis indicates that higher mortality in one sex leads to skewed ASR, which in turn may generate selection for SSD biased toward the rare sex. Taken together, our findings provide evidence that skewed ASRs in amniote populations can result in the rarer sex evolving large size to capitalize on enhanced mating opportunities.
AB - Body size often differs between the sexes (leading to sexual size dimorphism, SSD), as a consequence of differential responses by males and females to selection pressures. Adult sex ratio (ASR, the proportion of males in the adult population) should influence SSD because ASR relates to both the number of competitors and available mates, which shape the intensity of mating competition and thereby promotes SSD evolution. However, whether ASR correlates with SSD variation among species has not been yet tested across a broad range of taxa. Using phylogenetic comparative analyses of 462 amniotes (i.e., reptiles, birds, and mammals), we fill this knowledge gap by showing that male bias in SSD increases with increasingly female-skewed ASRs in both mammals and birds. This relationship is not explained by the higher mortality of the larger sex because SSD is not associated with sex differences in either juvenile or adult mortality. Phylogenetic path analysis indicates that higher mortality in one sex leads to skewed ASR, which in turn may generate selection for SSD biased toward the rare sex. Taken together, our findings provide evidence that skewed ASRs in amniote populations can result in the rarer sex evolving large size to capitalize on enhanced mating opportunities.
KW - Comparative method
KW - mating competition
KW - mating opportunity
KW - sex-biased mortality
KW - sexual selection
UR - http://www.scopus.com/inward/record.url?scp=85107772301&partnerID=8YFLogxK
U2 - 10.1111/evo.14273
DO - 10.1111/evo.14273
M3 - Article
AN - SCOPUS:85107772301
SN - 0014-3820
VL - 25
SP - 1636
EP - 1649
JO - Evolution
JF - Evolution
IS - 7
ER -