Courtship
patterns
Courtship
is the series of
behavioral actions performed by one or both members of a mating pair just prior
to spawning. Courtship has several functions that maximize effi - ciency of the
spawning act. Courtship aids in species recognition (a pre-mating
species-isolating mechanism), pair bonding, orientation to the spawning site,
and synchronization of gamete release. Courtship is often necessary to overcome
territorial aggression by the male, who might otherwise drive the female away
from the site (in many species, males already have eggs in their territories
and must guard against predation by conspecifics of both sexes). Courtship may
be relatively simple (as in herring), or may involve a large number or a
complex progression of displays and signals by one or both members (e.g., Corynopoma,
Characidae; Guppies; sticklebacks).
During
courtship, individuals frequently change color from their normal, countershaded
patterns to bolder, contrasting color patterns. In many species (e.g., minnows,
silversides, cichlids) existing body coloration intensifi es or the head
becomes dark relative to the remainder of the body. Sound production during
courtship, usually by the male, occurs in many fish families (sturgeons,
minnows, characids, codfishes, toadfishes, sunfishes, grunts, sciaenids,
darters, damselfishes, cichlids, blennies, gobies), often in accompaniment with
visual displays involving exaggerated or rapid swimming patterns, erection of fins,
and jumping out of the water (Fine et al. 1977; Myrberg 1981, 2002; Lugli et
al. 1997; Johnston & Johnson 2000; Lobel 2001; Johnston & Phillips
2003). Chemical stimulants are also involved. Male Goldfish, Zebra Danios
(Cyprinidae), and gobies begin courtship activities when exposed to water that
held a gravid female, and gravid female gobies are attracted to male-produced
androgynous substances (Hara 1982; Stacey & Sorensen 1991). Species and sex
recognition during courtship in cichlids occurs more quickly when individuals
receive both visual and chemical cues from potential mates (Barlow 1992).
Some
appreciation of the evolutionary premium placed on successful courtship can be
gained by realizing that the gas bladder muscles that produce the boatwhistle
mating call of the male Oyster Toadfish, Opsanus tau (Batrachoididae),
contract at a rate of 200 Hz. This makes them the fastest contracting
vertebrate muscles known, the next closest being the shaker muscles at the base
of the tail of rattlesnakes, which contract at only half that rate (Rome et al.
1996).
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