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sexual selection in birds

BIOL 307-B05 Assignment 2: Sexual Selection in birds 1
Jennifer Lowe, 24 February 2014
Research surrounding the causes and effects of sexual selection has come a long way since it was
of interest to Charles Darwin1, though all known forms are now encompassed with the current
description as successful mating variation2. Birds exhibit some elaborate examples of sexual
selection that are often results of male competition and/or female choice. In some species the
same male ornamentation is used for both competition and female preference3. Male
competition takes many forms and it does not always end at mate acquisition. For example,
sperm competition can occur when a female has had multiple mating partners4. Sexual selection
involving female choice occurs through several direct and indirect mechanisms5 and can act on
many different male adaptations such as courtship displays of song6, plumage ornamentation7,
physical displays8, nuptial gifts and/or paternal care9. It has also been shown that a species can
exhibit multiple female-preferred traits each related to a different aspect of male fitness10. There
are trade-offs associated with plumage ornamentation. Bright plumage can be an indicator of
male fitness as it is costly to produce and dull plumage may indicate health conditions11, 12. Also,
iridescent plumage has been shown to decrease the hydrophobicity of the feathers and water
repulsion is important in temperature regulation and feather cleaning13. Sexual selection for
exaggerated characters can be dulled when female choice fluctuates14 or when selection for those
characters must compete with selection for alternative characters15. Forms of indirect selection
that may result in dramatic male characters include the ‘runaway method’ in which female
choice and a male character become genetically correlated which causes positive feedback16 and
the ‘parasite hypothesis’ (a form of ‘good genes’ hypothesis) in which females show preference
for more ornamented males because they are more parasite-resistant17. The mechanisms of
sexual selection have been the focus of much debate as many of the factors involved are difficult
to measure (e.g. Female choice)5, 6.
BIOL 307-B05 Assignment 2: Sexual Selection in birds 2
Jennifer Lowe, 24 February 2014
Annotated Bibliography
Darwin, C. 1874. The descent of man: and selection in relation to sex. A.L. Fowle, N.Y.
A look at the evolution of human beings from a ‘lower’ organism and an elaborate comparison
between human beings and other animals with focus on thought. A great deal of attention is
given to the processes of selection with focus on sexual selection. Though Darwin has brought
up sexual selection previously, in this book he gives a more detailed description. The modes
described are male-male competition or female choice.
Searcy, W.A. & Yasukawa, K. 1995. Polygyny and sexual selection in Red-winged
Blackbirds. Princeton University Press, Princeton, N.J. Print.
A book that uses original and previous research to show how red-winged blackbird (Agelaius
phoeniceus) females can benefit and how the effects sexual selection can become greater by
mate-sharing. The book is also a great overview of sexual selection and shows how its definition
has required much elaboration since first proposed by Charles Darwin.
Griggio, M., Serra, L., Licheri, D., Monti, A. & Pilastro, A. 2007. Armaments and ornaments
in the rock sparrow: possible dual utility of a carotenoid-based feather signal. Behav Ecol
Sociobiol. 61:423-433.
[accessed 22 February 2014]
A study with rock sparrows (Petronia petronia) showing that males with larger throat patches
are superior at obtaining territory, defending territory and attracting mates. They experimented
with real birds and dummy birds showing that males appeared to be threatened by other males
with larger patches. To show that patch size was correlated to female choice, the patches of
males were experimentally manipulated.
Birkhead, T. 1998. Sperm competition in birds. Rev Reprod. 3:123-129
[accessed 22 February 2014]
A review that looks at the process and outcomes of sperm competition in extra-pair partnerships,
where female copulates with males other than her bonded mate, in several types of monogamous
birds. In these circumstances, males acquire many adaptations to increase their chances of
successful fertilization of the females.
Kirkpatrick, M., & Ryan, M.J. 1991. The evolution of mating preferences and the paradox of
the lek. Nature. 350:33-38.
[accessed 20 February 2014].
An review of hypotheses of evolution due to female preference. The selection processes of
interest are direct and two modes of indirect. Direct selection is the result of female preference
on the basis of direct benefits to her survival or reproductive success. Indirect selection can be
the result of the runaway process, in which a male trait becomes exaggerated when the trait and
the preference of the trait coevolve, or parasite hypothesis, when there is an association between
parasite resistance and elaborate male displays.
BIOL 307-B05 Assignment 2: Sexual Selection in birds 3
Jennifer Lowe, 24 February 2014
Catchpole, C.K. 1987. Bird song, sexual selection and female choice. Trends Ecol Evol.
[accessed 19 February 2014]
Shows how displays by female aquatic warblers and sedge warblers (Acrocephalus
schoenobaenus) in response to recordings of male song can be used to study female choice.
Without such indication from the females, it is difficult to determine if the selection process is
acting on female choice or other sexual selection processes.
Petrie, M., Halliday, T. & Sanders, C. 1991. Peahens prefer peacocks with elaborate trains.
Anim. Behav. 41:323-331.
[accessed 24 February 2014]
A study that tests the mating preference of female peafowl (Pavo cristatus). The authors
conclude that the more embellished the male’s train, the higher his mating success. They point
out that male competition does not have a significant factor because a female does not succumb
to distractions from other males once she has made her choice.
Byers, J., Hebets, E. & Podos, J. 2010. Female mate choice based upon male motor
performance. Anim. Behav. 79:771-778
[accessed 20 February 2014]
A review that suggests that physical displays by males are more important than ornamentation in
regards to female choice. This study also suggests that evolution of ornamentation was to
enhance the physical display rather than functioning as stand-alone adaptations. The reasoning
surrounding this assumption is that physical displays are a superior method of determining
overall fitness of an animal.
Wiggins, D.A. & Morris, R.D. 1986. Criteria for female choice of mates: courtship feeding and
paternal care in the common tern. Am. Nat. 128(1):126-129.
http://www.jstor.org/stable/2461291 [accessed 24 February 2014]
Includes previous studies and original research to show how nuptial gifts in the form of
courtship feeding by males can provide the female with much needed nutrients after copulation
and can indicate the level of paternal care that the male will perform. The authors own study of
the common tern (Sterna hirundo) revealed a large positive correlation between courtship
feeding and the care that the males provided their young.
Taff, C.C., Steinberger, D., Clark, C., Belinsky, K., Sacks, H., Freeman-Gallant, C.R., Dunn,
P.O. & Whittingham, L.A. 2012. Multimodal sexual selection in a warbler: plumage and song
are related to different fitness components. Anim. Behav. 84:813-821
[accessed 22 February 2014]
Use previous studies on male plumage combined with their own studies on male song to show
that female choice in the socially monogamous common yellowthroats (Geothlypis trichas) acts
on both characters. Like many socially monogamous birds common yellowthroats do practice
extra-pair mating in which a bonded female will copulate with multiple males. This study found
BIOL 307-B05 Assignment 2: Sexual Selection in birds 4
Jennifer Lowe, 24 February 2014
that success in acquiring a bonding mate is related to plumage and success in extra-pair
copulation is related to song.
Mougeot, F., Perez-Rodriguez, L., Sumozas, N. & Terraube, J. 2007. Parasites, condition,
immune responsiveness and carotenoid-based ornamentation in male red-legged partridge
Alectoris rufa. J Avian Biol. 40(1):67-74.
[accessed 23 February 2014]
A study that links health and immunity with ornamentation of carotenoid base. As the
researchers predicted, red-legged partridge (Alectoris rufa) males showing higher levels of
carotenoids in their ornaments showed a greater immune response. Coccidia parasite infections
were used to show the relationship between immune response and carotenoid levels. Another
factor that makes brighter ornamentation a good selection factor is that carotenoids must be
ingested from food hence revealing how apt a male is at survival.
Seifferman, L., Hill, G.E. 2005. Evidence for sexual selection on structural plumage
coloration in female eastern bluebirds (Sialia sialis). Evol. 59(8):1819-1828.
http://www.jstor.org.ezproxy.library.uvic.ca/stable/3449084 [accessed 23 February 2014]
A study showing that female fitness of eastern bluebirds (Sialia sialis) can be indicated by the
quality of melanin-based plumage. This study is interesting in that it shows sexual selection
acting on female characters as well as those of males. Laboratory experiments determined the
impact of nutritional stresses on plumage colouration. Field data was collected to evaluate the
relationships between plumage colour, mate choice and mating success.
Eliason, C. & Shawkey, D. 2011. Decreased hydrophobicity if iridescent feathers: a potential
cost of shiny plumage. J Exp Bio. 214:2157-2163.
[accessed 23 February 2014]
A study testing the hydrophobicity and self-cleaning efficiency of iridescent feathers and noniridescent feathers. Iridescent feathers have increased surface area due to films of keratin and
melanin coating the barbules resulting in the absorption of water. This is considered a cost
because birds rely on their feather to repel water which is a temperature-regulating mechanism
and self-cleaning mechanism.
Caine, A.S. & Lyon, B. 2008. Adaptive plasticity in female mate choice dampens sexual
selection on male ornaments in the lark bunting. Science. 319(5862):459-462
A study of the lark bunting (Calamospiza melanocorys) displaying that female preference for
male plumage characters can change from year to year and the result of this preference
variation is that sexual selection for those characters can be dulled. The difference in selection
for these traits can be so extreme that a trait can reverse from positive to negative selection from
one year to the next which may result in males to develop multiple characters that are sexually
selected for. In a dynamic environment, socially or ecologically, it is beneficial for the female to
have the ability to choose a male with characters that meet her changing needs.
BIOL 307-B05 Assignment 2: Sexual Selection in birds 5
Jennifer Lowe, 24 February 2014
Greene, E., Lyon, B.E., Muehter, V.R., Ratcliffe, L., Oliver, S.J. & Boag, P.T. 2000.
Disruptive sexual selection for plumage coloration in a passerine bird. Nature. 407(6807):1000http://www.nature.com.ezproxy.library.uvic.ca/nature/journal/v407/n6807/full/4071000a0.html
[accessed 18 February 2014]
A study that shows how different sexual selection process can result in disruptive selection where
both extremes of a character are selected for. Lazuli buntings (Passerina amoena) display
sexual selection for male competition and female choice. Young males with plain markings are
able to acquire favourable territory because other males do not see them as a threat, whereas
bright males are more likely to be favoured by females. The result is a bimodal distribution in
plumage coloration.
Hall, D.W., Kirkpatrick, M. & West, B. 2000. Runaway sexual selection when female
preferences are directly selected. Evolution. 54(6):1862-1869.
http://www.jstor.org/stable/2640532 [accessed 20 February 2014]
An analysis of runaway selection models where there is coevolution between female preference
of a male trait and the trait itself. This mechanism is thought to be responsible for at least some
of the most extreme male traits. Runaway can only occur if natural selection does not act
negatively on that trait and a stable equilibrium is not reached. This paper looks at many sexual
selection scenarios and hypothesizes as to which circumstances are more likely to result in
runaway evolution.
Hamilton, W.D. & Zuk, M. 1982. Heritable true fitness and bright birds: a role for parasites?
Science. 218(4570):384-387. http://www.jstor.org/stable/1688879 [accessed 22 February 2014]
The introduction of how female choice for elaborate male plumage may be correlated to male
parasite load and genetic resistance to parasites. Their hypothesis includes two predictions; that
parasites and their hosts co-evolve providing host with resistance and that when a female
chooses her mate on the bases of his showiness, she is also choosing him on the basis of his
health (eg. resistance to parasites).
BIOL 307-B05 Assignment 2: Sexual Selection in birds 6
Jennifer Lowe, 24 February 2014
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