SEXUAL BEHVIOUR FROM FISH TO MAN
E.M. ABDEL GAWAD
Dept. of Hygiene and Husbandry. Faculty of Veterinary Medicine, Cairo University, Giza
ABSTRACT
Sexual behaviour involves not only the act of mating itself, but also all those elements of courtship, display, motor activities and postures which have a functional unity with spawing or coitus to ensure fertilization, pregnency and propagation of the species.
Animal Courtship is essentially similar to human courtship. Both animals and humans like to formalize the mating transaction with some form of ritual, whether it be a display or a wedding ceremony.
Throughout the animal Kingdom there is a bewildering variety of courtship behaviour patterns, ranging from those species that reproduce without any behavioural interaction at all, to species that show very complex courtship sequences lasting for several hours or even days.
In Sexual interaction, some behavioural elements will be characteristic of the female and others of the male. The Sexually mature animal must be capable of recognizing the species, sex, and exact status of sexual readiness of a prospective mate.
Many animals have an intromittent organ (The penis in mammals) by means of which the sperm transfer is effected ,. Some accomplish copulation without specialized intromittent organ as in birds except ducks and few other by a quick apposition of their cloacae (cloacal kiss)
The extrusion of the sex products into the surrounding medium (external fertilization),common in water-living forms, is of course impossible in land living animals, since the gametes would be quickly killed by drying in air, thus internal fertilization is necessary in land-form.
The mating system that is typical of a species provides a fundamental aspect of its social organization, monogamy, polygamy, polyandry and promiscuous are common
Sexual behaviour in fishs, birds, reptiles, insects and mammals has been illustrated and analyzed.
INTRODUCTION
Man’s interest in animal life has perhaps never been greater that it is today. The latest studies in comparative behaviour have shown that essential components of human behaviour can be understood genetically as something we inherited from our ancestors. Therefore, an understanding of animals become a prerequisite for an understanding of man
( Grzimek, 1972 ).
The time it takes for an animal to reach sexual maturity depends on two factors : the size of the creature and its span of life. Small animals rarely live long. They have opted for a strategy of rapid reproduction and hence, quick colonization of new habitates. The other extreme of this situation is to leave reproduction until late in life and become a large animal. Many Creatures fall between these two extremes ( Whitfield 1979)
The reproductive urge is released by chemical and physical changes in the body, As the breeding season approaches, the gonads secrete sex hormones into the blood stream. The overwhelming coercion that these hormones exert on the body leads to surprising changes in behaviour (Nicolai,1975).
General environment, recent events, and presently occurring stimuli ( or lack of such ) also influence its behavior. Level of nutrition, seasonal effects such as day length and temperature, presence or absence of good health, earlier experience, and learning can all influence the activity seen ( Criage, 1981 )
Biologists have shown beyond any reasonable doubt that, with a few exceptions, the performance of species–typical behaviour contributes to the biological fitness or more accurately the inclusive fitness (Hamilton, 1964) of the behaving animal ( Hind 1975 ). Behaviours which are neutral or confer a biological disadvantage will disappear from the population under the forces of mutation and natural selection (Hind, 1975)
COURTSHIP AND DISPLAY
Courtship is the term used by ethologists to embrace all behaviour that precedes and accompanies the sexual act that leads to the conception of the young ( Mcfarland, 1981 ) . The essential components of courtship are : attraction, pursuit and a period of time before mating occurs. For many animals the relationship, or pair bond, may continue while the young are brought up or even for life ( Whitfield, 1979 )
Displays are stereotyped motor patterns involved in animal communication., Displays are largely genetically determined and species-specific. Related species often haven similar displays. Display postures often show distinctive color patterns, weaons, or other physical characteristics. (Mcfarland, 1981)
Sexual display consists of discrete components of behaviour which usually occur in a fairly strict order to give a sequence of behaviour which will be species-specific a phenomenon known as «Behavioural chains».
The Functions Of Courtship
1- Advertisement : -
Clearly one of the problems in mating is the recognition of appropriate mates not only as to sex but also to readiness to mate. Behavaiours that “ advertise “ the sex and readiness of the mate constitute one class of courtship. Whereas the male of many vertebrate species is continuously sexually active during the reproductive season, the female is suitable as a mate only during a limited estrus (Etkin,1969)
· Many male birds posture infront of the female in such away that their plumage patterns are shown off to best advantage,. the displays of peacocks (pavo cristatus) are particularly spectacular example (McFarland. 1981 )
· The male smooth newt performs a complex displays that includes posturing to show off his brilliant colouration, and a tail fanning movement that produce a water current directed toward the female which carries his smell to her the female newt is-thus stimulated through three sensory channels, visual, olfactory and tactile
· The male fiddler crab of the species Uca maracoani performs lateral waving of large claw as female approaches then descends into burrow. Female often respands by following male into burrow and mating there (Bliss, 1990)
· Secretions produced by the female in one fish were found to stimulate mating behaviour.in the male (Tavolga, 1956)
Since most mammals are primary nocturnel non-visual animals, they use the sense of smell widely. Many female mammals in heat can apparently be recognized by odors, sometimes form special anal gland like those of the cat. Male rates distinguish estrous from non-estrous females, even at some distance, by odor, and male dogs are attracted to the urine of the estrous bitch (Etkin, 1969).
· In female chimpanzees and some other female primates the estrus state includes swelling and reddening of the so called sexual skin in the perineal region. In addition, the estrous female in mammals generally shows behaviour that differs from the non-estrous condition, she stands still for the male and tolerates his sniffing and eventually his mounting behaviour. The advertisement display of the female in estrus are, however, not a particularly elaborate aspect of courtship in vertebrates, because the male generally maintians sexual receptivity continuously during the rut and actively seeks the female .
Advertising displays of the male are more conspicuous though perhaps not more common aspect of animal courtship. We appreciate this best in birds, lizards, and some fish which like the human are visual minded.
2- Overcoming Of Aggression : -
Another function which courtship serves is that of overcoming the aggressive responses of one animal to another. When a female baboon comes into heat she displays her genitals in the so-called persentation posture thus courtship behaviour in the female monkey consists principally of subordination, sexual receptivity and acceptance of punishment from the dominant male (Carpenter, 1942).
Solitary preadaceous mammals, particulary of the cat and weasel family, often do considerable fighting as part of their coutship. The mating of cats is accompanied by much scratching, biting, and appropriate vocalization. This behavior differs from than fighting. Behaviorally, it appears to be fighting behaviour normal to a predator but modified and controlled by stimuli emanating from the sexual situation (Etkin – 1969).
In many spiders the male ties the female down with silken threads before mating with her to suppress or circumvent her cannibalistic tendencies (Mcfarland 1981)
3- Physiological co–ordination of male and female :-
Successful reproduction requires as a minimum the co- ordination of male and female activity with respect to insemination. In many rodents, rats, guinea pig., queen and sow, etc, when stimulated by the male during estrus, the female show a special posture called Lordosis. In this, the back is arched downward in the center, bringing the genital region up and the tail is lordotic posture, of course, directly assist in permitting the male to achieve intromission.
In birds, cloacal kiss facilitats transfer of the sperm to the female during breeding as when the male mounts the back of the female momentarily so that their cloacas are closely appressed and the transfer effected quickly (Wallace and Mahan 1975) .
4- Reproductive isolation : -
The function of many courtship patterns is to minimize the risk of hybrid matings, and to ensure that mating occurs only with an individual of the same species. This phenomenon is called reproductive isolation, and any behavior pettern that achieves it is called «isolating mechanism». To ensure the survival of its offspring it is of paramount importance that an animal mates with a member of its own species, since hybrid mating rarely produces any offspring at all, and those that are produced are unlikely to survive or to produce further offspring themselves. ( Etkin, 1969 Whitfield. 1979, and Mcfarlond. 1981).
5- Prevent Pridation Risk
Mated pairs of colonial birds often display within sight of their neighbours, and the mutually stimulating effect of this displays tends to bring the members of the colony into reproductive condition at the same time. This has the advantage that the eggs and young are produced in large numbers during short period of time, thus swamping the predators (Mcfarland, 1981). This is called the Fraser Darling effect.
COPULATION
Copulation is that part of sexual behavior which is most closely associated with fertilization of the egg by the sperm. The copulatory behavior may be seen as a sequence of chain responses in which one event leads to another in a sterotyped manner.
1- Sexual behavior in Fish
A recent Painstakingly–researched study is that of Myrberg (1972) on the bicolor damselfish ( Eupomacentrus partitus ) . This is a tropical marine fish – the male exhibits a number of displays to the female which, since they precede spawing, can be considered as courtship these are : -
1- Tilt :- the body is quickly tilted to one side some 20 – 40 and then returned to the vertical
2- Dip : - A rapid, eye–catching vertical dive from 1 – 2 metres above the bottom.
3- Nudge :- the male approach the female with his head lowered and pelvic fin expanded, and attempt to push his head and neck against the female’s cloaca
4- Lead : - the male move rapidly in front of the female and toward his nest conch. His tail movements are exaggerated
5- If the female follow the male, then a further series of elements are displayed
6- Quiver : - the male stands on his head near his nest conch and quiver his body rapidly.
7- Close swim : - If the female enters the nest area, the male swims quickly over to her and they move together in a circle around the nest.
8- Skim : - both sexes swim a short distance over the nest, vibrating slightly.
9- Spawing : - this is skimming over the nest during which the female deposits eggs and the male sperm (milt) the spawing period may last between 10 minutes and and 2 hours.
10- Flutter :- if, during these elements the female moves away from the nest area, the male perform fluttering to attract her back.
2. Sexual behavior in Fiddler–Crab :
The Courtship displays of fiddler–Crabs consists of rhythmic waving of the enlarged claw accompanied by body movements, so that the display looks like a dance. The movement varies in different species, but it is always Stereotyped within each species (Crane, 1957). In the Philippine species Uca zamboagana a series of vertical waves of claws is accompanied by raising and lowering of the body. In South American species Uca pugnax. rapax the enlarged claw moves outwards and upwards in three jerks and descends smoothly.
3- Sexual behavior in Frogs : -
In frogs and toads ( Anura ), the male clasps the female from above and maintains this position throughout the deposition of the eggs, fertilizing them as they emerge from the females cloaca. If the object clasped another male, a few rapid vocalizations from him serving as a signal, and the clasping grip is released (McFarland, 1981). Copulatory behavior may be seen as a sequence of chain responses. Male clasps object female forms lordosis position male forms pasket female discharges eggs male fertilizes eggs.
4- Sexual behavior in lizards : -
Ferguson (1970) in a study of side – blotched lizards (Uta stansburiana) which live in the desert and semi – desert regions of southern United States, mentioned that the basic pattern of copulation in this species has six stages.
Stage 1: - the male approaches the female, while maintaining aggressive display in which the back is arched, he gives a sene,s of puch–ups and down. These threat postures relax as he approaches the female, and perform courtship nods of the head.
Stage 2 and 3 : - As the male nears the female he licks her tail, hind legs, and pelvic region, continuing to head nod. Sometimes he circles the female.
Stage 4 : - the neck in grasped, often with some preliminary nipping, and the female is swung about or dragged along by the male. The female during this stage tells the male that she is receptive.
Stage 5 : - the male puts on leg over the pelvic region of the female and moves it rhythmically back and forth, pushing the base of his tail against her
Stage 6 : - In copulation proper , the male thrusts his Cloaca forwards until the penis is inserted. There are then a series of thrusts, culminating in ejaculation
5- Sexual behavior in Queen butterfly
Brower, Brower and Cranston, (1965) studies the courtship behavior of the Queen butterfly Danaus gilippus and mentioned that the sequences of responses performed by the male and female are kept in phase with one another. This occurs because each act of one individual is released by the previous response of the partner and provides the stimuli for the Partner’s next act. The whole ritual consists of an elaborate chain of responses analogy with Courtship in some vertebrates, such as the three-Spined Stickleback fish (Evans, 1968).
6- Sexual behavior in birds : -
Etholgists have given a great deal of attention to the specific variations in the behaviour of waterfowl. In fact, following Darwin it was Oskar Heinroth (1910) Who in his paper, on the biology and ethology of Anatidse drew exactly his conclusion from the analogies found in the behavior of birds and human. Heinroth used Courtship in water fowl as a mean of taxonomy to distinguish between species. Lorenz (1971) has fully confirmed Heinroth‘s assertion.
-The marriage market of the mallard.
After the mallard drakes have assumed their significant breeding plumage following the autumn moult,they gather on fine days in October and November on their home waters and form small groups for communal display (Nicolai. 1975). This display is usually triggered off by a duck suddenly shooting out among the drakes, stretching out her neck along the water surface and then retracting and extending it in quick succession, this is called (Nod–Swimming) . All the drakes present react together to the ducks nod – swimming by a specific synchronous display movement, the ( grunt – whistle ), this is followed by further display movement: down-up , head-up-tail-up, turning the head towards the female, again carried out simultaneously by all the drakes. The group displays of the mallard drakes gives the marriage – hungry females on opportunity to compare the attractiveness of the assembled males.
The duck signifies her intention to the drake she has selected by a peculiar behavior pattern. She goes up to him, swim eagerly behind him and with grumbling sequences of sounds she threatens over her shoulder at another drake in the display group. This so called “ inciting “ is to indicate her intended that she in fond enough of him alone to keep other equally valid competitors at bay.
If a duck continues to propose to the some drake on several consecutive days, the bond between then gradually strengthens and they eventually become a pair. The drake accompanies the duck in the search for a suitable nesting site, but he does not participate in incubating the eggs.
6- Sexual behavior in mammals : -
Copulation in mammalian species is characterized by intromission, a term which refers to vaginal penetration by the penis. In some species ejaculation is achieved with a single intromission, while in others multiple intromissions are necessary.
6-1 Primates : -
The copulatory behavior of primates is varied, multiple intromisston occur in some monkeys such as the rhesus macaque, but a single intromission is also common, especially among the apes. Thrusting is universal, multiple ejaculation normal, with the exception of gorilles and chimpanzees foot clasp is found in some monkeys ( Mcfarland, 1981).
The human female is continuously sexually receptive the sustained sex interest of the partners thus favors the intgration of the male ( Chance , 1962). Furthermore, in the absence of a definite estrus period, the specific stimuli furnished by the usual mammalian female as a sign of estrus (i.e. odors, sexual skin color,etc) are–no langer functional and have dropped out. Sexual play in humans is greatly facilitated by the assumption of the upright posture, which makes ventral copulation possible, replacing the awkward posture found in other Primates (Etkin, 1969).
6-2 Carnivores
In some species there is a genital lock which results in the copulating partners being temporarily unable to separate once intromission is achieved. In dog (cans) for example, the end of the penis become enlarged, and a vaginal sphincter muscle closes arround this enlargement, in cats (Felidae) the neck grip occurs
6-3 Rodents : -
Rodent Copulatory behavior is characterized by multiple intromissions and ejaculations. Evidence from the laboratory rat (Ratus norvegicus) suggests that this facilitate the transport of sperm within the female reproductive organ . A period of quiescence following ejaclation is necssary for successful implantation of the fertilized ova
MATING SYSTEMS
The mating system is a species – specific provides the social nature of the animal in relation to their ecological niche
1- Monogamy :-
Over 90% of the birds of the world are monogamous, but monogamy is rare in other animals, including mammals each breeding adult mates with only one member of the opposite sex such relationships are found amongst Swans, Geese, Cranes and gibbons .
2- polygamy :
polygamy is much more common among mammals. An individual generally has two or more mates either successfully or simultaneously.
3- polyandry: -
The female mates with too or more males. The American jacana is an example. Having successively counted, the female lays the eggs, which are incubated solely by the male, while the female attempts to gain more males to incubate successive clutches.
4- Promiscuous : -
|There are no pair bends, and both males and females mate with more than one member of the opposite sex
RERERENCES
Bliss. D.E (1990): Shrimps, lobsters and Crabs. Columbia University press. New York
Brower,L.p.,Brower,J.V.and Cranston,F.P.(1965): Courtship behaviour of the Queen butterfly Danaus gilippus berenice (Cramer). Zoological, 50, 1-40
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