Stone, scissors, paper

In the harsh world of natural selection, the most adapted survive, that is, one who leaves more offspring. Males try as they can. The extreme option is to disperse all competitors in the district and subordinate the maximum number of females. But there are other strategies, not so aggressive, but no less successful.

For example, while some males fight for females, protect the territory and form a harem, others evade the battle and penetrate into the harem through the back door. Depending on the chosen strategy, males look different: aggressive seek to suppress their opponent with one appearance, small and weaker are trying not to reach the leaders, but, on the contrary, become as inconspicuous as possible. This is how real dimorphism occurs.

An example of such dimorphism is the dung beetles of the family of plate-eared Scarabaeidae : individuals have larger horns, there are no small horns (see the TRV-hunger No. 159). Rogachi fight; Small - quiet people, teasing females left without protection. The size of the male depends on the power of the larva: if there was a lot of feed, the larva will grow a large and adult insect will be large and horned. The fish of the blue swordsman Xiphophorus nigrensis Males differ in size and behavior strategy. Small males ripen earlier and chased for females, large ones grow up later and take care of females. This difference is controlled by one locus in the Y chromosome.

Males of Ktenophorus decorated with CTENOPHORUS Pictus From the family of agamous lizards two colored morphs. Red males suppress yellow and like females more, but the sperm of the yellow males is more successful for them. Accordingly, their reproduction strategies are different: red males guard females, yellow are inhibiting.

There are many examples of male dimorphism, but in recent years reports of trimorphism have appeared. Perhaps the best -style iguans UTA ​​have been best studied in this regard Stansburiana , which has been explored by the professor of the University of California (University of California, Santa Cruz) Barry Sinevo (Barry Sinervo). The males of these lizards are distinguished by the color of the sides and the neck, and each color morph corresponds to a certain behavior strategy (Fig. 1).

Orange males, the most powerful and aggressive, grow in the vicinity and capture protected areas and females belonging to males with a blue throat. Garems have less harems than the orange. However, there are still yellow males, outwardly reminiscent of females; They do not guard anything and do not attack anyone, and stealthily meet with females who were conquered by orange.

Yellow males have a large volume of sperm, which has a high fertilizing ability, so that this morph does not take external power, but with internal content. At the same time, yellow loses blue, which vigilantly protect their relatively small territory and do not pass the yellow quiet people. Each strategy allows you to overcome one morfu, but grazes in front of another. The interaction between them resembles the game "Stone - scissors - paper."

The color of the iguana depends on the three alleles of one gene: o - Orange , b - Blue , Y - Yellow . They form 6 combinations: OO -Bright orange, BB -Dark blue, uu - yellow; by have throats with pale blue and pale yellow stripes; Bo -blue and orange stripes on the throat and pale orange sides; yo - Light orange. Individuals with allele o ( OO , Bo , Yo ) are always aggressive, allele y In the absence of about ( by , yy ) gives rise to tikhushnikov, and bb homosigo Determines the "blue" strategy.

The success of fertilization depends in males on the color of the closest neighbors. The fitness of the yellow is maximum when they are surrounded by orange; orange - among the blue; blue - among the yellow. The often alleles and the ratio of morph fluctuate with a frequency of 4–5 years. These fluctuations are also affected by the certain plasticity of the BY genotype. To Mr. there are many orange males around, they are yellow. But in the absence of orange, it is beneficial to be blue. Then in the blood by by The concentration of the hormone of testosterone increases, they turn blue and behave accordingly. (The gene involved in the definition of coloring is probably responsible for the concentration of steroid hormones). The reverse transition is impossible - the blue lizards do not turn yellow.

Other factors affect the fitness of the morph: the size and quality of the site that the male occupies, as well as the preferences of females.

The female u . Stansburiana Only two color variations, orange and yellow, and, accordingly, two reproduction strategies. Orange females make large masonry, from which small lizards are removed, there are few yellow eggs, but they are large. Orange lizards flourish at a low population density, producing numerous offspring. Yellow succeed in high density, when the selection favors large eggs among many small ones. The number of orange and yellow females fluctuates with a frequency of two years, two generations.

Genes that provide the differences between color morph also determine the hormonal background, masonry and eggs, endurance and behavior of individuals, the function of the immune system. There are so many correlations that other genes are also involved in them.

The strategy "Stone - Scissors - Paper" is characteristic not only of spotted iguans. Barry Siner-in and his colleagues found her from the European viviparous lizard Lacerta Vivipara . She, like Iguana, has three alleles of one gene ( o , y , w ) determine the color morphs of males and the strategy of their behavior, as well as the mass, body size and endurance of lizards. (Endurance of reptiles was tested on a treadmill, which moved at a speed of 0.5 km/h. ) L. Vivipara , homozygous in these alleles, respectively, orange, yellow or white tummies. Heterozygotes give rise to variations with stripes and spots.

Orange males are aggressive, strong and defeat whites, who protect the territory and drive yellow males who strive to pretend to be females. Researchers watched the lizards living in French Pyrenees. Observations showed that the reproductive success of males depends on how the older generation was the ratio of morph ratio of morph. Their allele frequencies fluctuate with a frequency of 3-4 years at an altitude of 300 m and 6–8 years at an altitude of 1,500 m. At large heights, the lizards develop more slowly, and females lay only one masonry, at low altitude there are up to three clutches per year.

Mark Rowland (Mark Rowland), Researcher at the University of New Mexico, and Douglas J. Emlen, professor at the University of Montana, described captured trimorphism in five types PHANAEUUS , Frozen Rogans of the Lucanidae family and coils Curculionidae (Fig. 2). In bumps, it manifests itself in the size of the horns, among the hornes - in the size of the jaws, among the weevils - in the length of the breast spikes. Dovozniks describe male dimorphism, depending on the abundance of food. But obviously, there are some other factors, possibly genetic, which affect the appearance of the third morph.

In alpha-samks, the size of the horns/jaws/spikes is the largest and correlates with the body length, in beta-samks, the size of these devices is smaller and the allometric ratios between them and body length are disturbed, the gamma samers look like females. Obviously, different morphs use various tactics of reproduction (struggle/protection, secret penetration and mimicry under the female).

Researchers do not exclude that female trimorphism is widespread in bugs much wider than before, and in populations for which dimorphism is described, for example, “horn or nothing”, horned males are actually beta, and sprayed - gamma; In populations, where the horn is either large or small, males with large horns are alpha, and with small - beta.

American researchers Stephen Schuster and Michael SHUSTER, Michel WADE found three remote forms in Paracerceis crumbling cancers Sculpta . They live in the Gulf of California and multiply in the cavities of the sponges. Large alpha samks protect harems inside the lips, smaller beta get inside, simulating the behavior and appearance of females, completely tiny gamma make their way into large gamers secretly and remain there.

The reproductive success of a particular morph depends on the ratio of males and females inside the sponge. So, the alpha male are most pronounced when they protect a sponge containing a single female and one beta or gamma sametz. Several males of the same type share reproductive success equally; If in the harem one alpha and one beta-male, then the beta accounts for 60% of the offspring; If there are one alpha and three gamma samets, then each of the gamm has 8% of the offspring, alpha-the rest; With a ratio of two alpha and three gamma, the offspring is distributed equally between the gamms.

The appearance of the male is determined by the three alleles of one autosomal gene that affects the growth and ripening speed. Gamma samers grow up in 57–58 days, beta-samers on average in 62 days, alpha-over 83. The difference in ripening speeds does not affect the reproductive success of males: the faster they grow up, the less offspring they manage to leave. But in general, the researchers did not notice the advantages of any of the three morphs.

From the Netherlands report trimorphism by Turukhan Philomachus PUGNAX , birds of the Bekasov family. This bird has a pronounced sexual dimorphism, and males adhere to two propagation strategies. There are “independent” males who live and protect their small marriage areas from other applicants, and “satellites” who quietly mate with chicken that come to look at the battles of independent males.

Each strategy strictly corresponds to a certain coloring of marriage; In addition, males are slightly different in size. It is generally accepted that behavior is determined by one autosomal gene with two alleles, the frequency of which is approximately constant: from 5 to 15% of males in the population - satellites. The researchers caught and examined more than a thousand birds and found among them 22 male intermediate sizes: they are larger than females, but a little less than the rest of the males. The coloring of the plumage was similar to the coloring of females, but a blood test confirmed that their floor was male.

Later, the researchers were convinced that the birds have testes, but at first they were placed in the aviary along with females and males with different behavior strategies and watched them from the beginning of the marriage season until the end of the year. Observers recorded 25 contacts with the participation of wife -like males, and in 13 cases they were interested in independent males, in seven they themselves climbed onto independent males, in four at the satellites, and once a female climbed into the wife -like individual. Females never climb on obvious males.

In natural conditions, female -like males imitate female behavior, one such bird was launched on a current, where it attracted the attention of obvious males of both types. At the same time, the volume of the testes in wife -like males is 2.5 times more than in ordinary ones. Perhaps they are quiet on occasion. Researchers suggested calling this rare morph Faeder - The old English version of the word "father". The genetics of this morph has yet to be found out.

Researchers who have discovered and studied the trimorphism of males in different species of animals believe that a system in which males create harems and control access to it, so that one paternity, and nothing to do, and females bring large offspring, aggravating this inequality, should generate alternative reproduction strategies, including a model of “stone - scissors - paper”. Probably, this model is widespread in the animal kingdom, but many cases have not yet been described.

1. Century . Sinervo (2001). Runaway Social Games, Genetic Cyvels Driven by Alter National Male and Female Strategies, and The Origin of Morps, Genetica 112 - 113: 417 - 34.

2. C. Bleay et. Al. (2007). An Experimen Test of Frequency-Dependent Selec Tion on Male Mating Strategy in the Feld. ProC. R. SOC. B: 274, 2019 - 2025.

3. B. Sinervo et al. (2007). Models of Density-Dependent Genic Selection and New Rock-Paper-Scissors Social System. The American Naturalist, 170, 5: 663 - 680.

4. JM Rowland et al. (2009). Two Thresholds, Three Male Forms Result in Facultation Male Trimorphism in Beetles. Science 323: 773 - 776.

5. M. Shuster et al. (1991). Equal 5. Mating Success Among Male Reproduc Tive Strategies in a Marine ISopod.

6. Nature 350: 608 - 610.

7. J. Jukema et al. (2006). Permanent Female Mimics in a Lekking Shorebird. Biol. Lett. 2: 161 - 164.