DETERMINATION OF SEX DUE TO ENVIRONMENTAL
Date: 2015-10-07; view: 458.
Determine the reliability of changes in sex ratio of the offspring by calculating the average error for the ideal numbers corresponding to the expected ratio of 1:1 for the various types shown in Table 4, if we take n equal to the sum of males and females in the table.
Sex ratio in the offspring of some animal species
Analysis of the conditions, under which, historically, each of these species occurred, demonstrates the feasibility of such biological changes. For example, spiders' huge number of males in the mating season is devoured by females, so a high percentage of males at the output of eggs are a device type in the struggle for life. Consider the table 1
Although, as a rule, the numerical sex ratio is really close to 1:1 in offspring of plants and animals, however there are significant deviations from the expected ratio in the posterity of individual species.
Table 1
| Species | The number of males per 100 females |
| Sheep | |
| Pigs | |
| Pigeons | |
| Man | |
| Bird Swift | |
| Fish, monkfish | |
| Squid | |
| Spider Lactodestes |
There are some kinds of plants and animals in which the sex of offspring is determined by the external environment. An interesting example in this sense can serve as a marine worm Bonelli. The proboscis females have chemicals that can determine the sex of larvae.
Female Boonellia viridis
Total preparation, fixed between glasses
Consider a female marine worm Bonelli. Note the relatively large body with long proboscis. Female Bonelli is developing when larvae is attached to the bottom after a period of free floating.
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