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The exception is sub-Saharan Africa, where more females than males are infected. Adult males are more likely to be diagnosed with tuberculosis. Some other sex-related health differences include: Anterior cruciate ligament (ACL) injuries, especially in basketball, occur more often in females than in males. [140]
Sex ratio by country for the population below age 15. Blue represents more boys, red more girls than the world average of 1.07 males/female. Sex ratio by country for total population. Blue represents more men and boys, red more women and girls than the world average of 1.01 males/female. Sex ratio by country for the over-65 population.
This can cause a discrepancy in the sex ratios as well. In the bluestreak cleaner wrasse, there is only one male for every group of 6-8 females. If the male fish dies, the strongest female changes its sex to become the male for the group. All of these wrasses are born female, and only become male in this situation.
Cases where the male is larger than the female have been studied as well, [136] and require alternative explanations. One example of this type of sexual size dimorphism is the bat Myotis nigricans, (black myotis bat) where females are substantially larger than males in terms of body weight, skull measurement, and forearm length. [137]
Females would increase in the population until the sex ratio was 2 females: 1 male, meaning that a male could have twice the offspring a female could. As a result, males will be twice as costly while producing twice as many offspring, so that males and females provide the same proportion of offspring in proportion to the investment the parent ...
The INAH-3 is significantly larger in males than in females regardless of age [1] and larger in heterosexual males than in homosexual males and heterosexual females. [2] Homologs of the INAH-3 have been found to play a direct role in sexual behavior in quails , [ 3 ] rhesus macaques , [ 4 ] sheep , [ 5 ] rats , [ 6 ] mice , [ 7 ] and ferrets .
In polyandrous species where some females mate with multiple males (and others get no matings) and males mate with one/few females (i.e., "sex-role reversed" species), these predictions from the Trivers–Willard hypothesis are reversed: parents in good condition will invest in daughters in order to have a daughter that can out-compete other ...
In many insects, the larval period of females is longer than that of males, and as a result of this extended growth period, these female insects are larger than their male conspecifics. [1] Male simian primates are generally larger than females of the same species due in part to extended growth periods. [ 2 ]