Multiple sexual ornaments#Sexual interference hypothesis

There are several hypotheses that attempt to explain why a male would have multiple sexual ornaments.

The multiple message hypothesis{{cite journal | last1 = Møller | first1 = A. P. | last2 = Pomiankoski | first2 = A. | year = 1993 | title = Why have birds got multiple sexual ornaments? | journal = Behavioral Ecology and Sociobiology | volume = 32 | issue = 3 | pages = 167–176 | doi=10.1007/bf00173774| s2cid = 25591725 }} states that different ornaments signal different properties of an individual's overall quality. Models support the possibility that this hypothesis is evolutionarily stable{{citation|last=Johnstone|first=Rufus A.|year=1996|title=Multiple Displays in animal communication: 'backup signals' and 'multiple messages.'|journal=Philosophical Transactions: Biological Sciences|volume=351|issue=1337|pages=329–338|doi=10.1098/rstb.1996.0026}}. but empirical tests are lacking.

Some ornaments represent long-term or short-term changes in overall condition. Elegant plumes in a bird or antlers in a deer grown once a year could signal the overall condition of an animal during the long period of growth; this is thus an example of a long-term change.{{citation|last1=Moller|first1=A. P.|last2=Pomiankowski|first2=Andrew|year=1993|title=Why have birds got multiple sexual ornaments?|journal=Behavioral Ecology and Sociobiology|volume=32|issue=3|pages=167–176|doi=10.1007/BF00173774|s2cid=25591725 }}. Secondary characters like the inflatable bare patches of skin on a grouse species or the colorful patches of skin in a primate species could represent short-term changes.{{citation|last1=Changizi|first1=Mark A.|last2=Zhang|first2=Qiong|last3=Shimojo|first3=Shinsuke|year=2006|title=Bare skin, blood and the evolution of primate colour vision|journal=Biology Letters|volume=2|issue=2|pages=217–221|doi=10.1098/rsbl.2006.0440|pmid=17148366|pmc=1618887}}.

The redundant signal hypothesis,{{cite journal | last1 = Zuk | first1 = M. | last2 = Ligon | first2 = J. D. | last3 = Thornhill | first3 = R. | year = 1992 | title = Effects of experimental manipulations of male secondary sex characters on mate preference in red jungle fowl | journal = Animal Behaviour | volume = 44 | pages = 999–1006 | doi=10.1016/s0003-3472(05)80312-4| s2cid = 53172540 }} also known as back-up signal hypothesis,{{Cite journal|url = http://www.mv.helsinki.fi/home/ucandoli/pdfs/Candolin%20Biol%20Rev%2003.pdf|title = The use of multiple cues in mate choice|last = Candolin|first = Ulrika|date = 2003|journal = Biological Reviews|doi = 10.1017/s1464793103006158|volume=78| issue=4 |pages=575–595|pmid = 14700392|hdl = 1975/138| s2cid=8577794 |hdl-access = free}} states that each character can only best show partial representation of overall condition. If each ornament reflected the male's quality with a certain error, then mate choice based on a single trait would lead a female to select a male in poor condition rather than one in great condition. Thus, a female ought to look at multiple sexual traits of a male if she wants to get an overall view of the male's quality. The redundant signals hypothesis differs from the multiple messages hypothesis, as the latter predicts that different signals reflect the same aspect of mate quality, whereas the former predicts that different signals reflect different aspects.{{Cite journal|url = http://www.mv.helsinki.fi/home/ucandoli/pdfs/Candolin%20Biol%20Rev%2003.pdf|title = The use of multiple cues in mate choice|last = Candolin|first = Ulrika|date = 2003|journal = Biological Reviews|doi = 10.1017/s1464793103006158|volume=78| issue=4 |pages=575–595|pmid = 14700392|hdl = 1975/138| s2cid=8577794 |hdl-access = free}} There has been some empirical support of this hypothesis.{{citation|last1=Jawor|first1=Jodie M.|last2=Breitwisch|first2=Randall|title=Multiple Ornaments in male northern cardinals, Cardinalis Cardinalis, as indicators of condition|journal=Ethology|volume=110|issue=2|pages=113–126|doi=10.1111/j.1439-0310.2003.00962.x|year=2004|bibcode=2004Ethol.110..113J }}. However, the majority of studies showed no correlation, suggesting the redundant signals are less common in indicating mate quality compare to other hypothesis like multiple messages hypothesis.{{Cite journal|title = Sexual selection in the zebra finch Taeniopygia guttata : condition, sex traits and immune capacity|last = BIRKHEAD, T. R., FLETCHER, F. & PELLATT, E. J|date = 1998|journal = Behavioral Ecology and Sociobiology|doi = 10.1007/s002650050530|volume=44 | issue=3 |pages=179–191| s2cid=28012906 }}{{Cite journal|title = The role of male ornaments and courtship behavior in female mate choice of red jungle fowl.|last = ZUK, M., THORNHILL, R., LIGON, J. D., JOHNSON, K., USTAD, S., LIGON, S. H., THORNHILL, N. W. & COSTIN, C|date = 1990|journal = American Naturalist|doi = 10.1086/285107|volume=136| issue=4 |pages=459–473| s2cid=84372337 }}{{Cite journal|title = The evolution of multiple male traits in the yellow-browed leaf warbler|last = Marchetti|first = Karen|date = 1998|journal = Animal Behaviour|doi = 10.1006/anbe.1997.0586|volume=55| issue=2 |pages=361–376| pmid=9480704 | s2cid=6223503 }}

The unreliable signal hypothesis suggests that some signals are unreliable indicators of overall male quality. Therefore, a female should look at multiple traits because one trait could be misleading. There is some support for this hypothesis.{{citation|last=Omland|first=K. E.|year=1996|title=Female mallard mating preferences for multiple male ornaments|journal=Behavioral Ecology and Sociobiology|volume=39|issue=6|pages=353–360|doi=10.1007/s002650050301|s2cid=1853483 }}.

The sexual interference hypothesis{{cite journal | last1 = Lozano | first1 = G. A. | year = 2009 | title = Multiple cues in mate selection: the sexual interference hypothesis | journal = Bioscience Hypotheses | volume = 2 | issue = 1| pages = 37–42 | doi = 10.1016/j.bihy.2008.09.001 }} proposes that additional male signals evolve to hinder female mate choice by interfering with the propagation and reception of other males' sexual signals. Females respond by evolving the ability to glean meaningful information from signals despite males' attempts at obfuscation. In turn, males respond by improving their interference signals and producing new signals that are not so easily blocked. This iterative co-evolutionary process increases the costs of assessment for females and the costs of signal production for males, and leads to temporary equilibria of honest advertising via multiple signals.

{{Reflist}}

• {{Commonscatinline|Multiple sexual ornaments}}

{{Sex (biology)}}

Category:Animal sexuality

Category:Evolution of animals