In fact, the term "sex-ratio" is misleading, and the formula "males/females" should be avoided. Only a minority of authors use this formula.

Practically, most authors use the formula "males/(males+females)". This can be expressed as a probability (range: 0-1) or as a percentage (*100). It should be properly called "male proportion" but the (misleading) term "sex ratio" is traditional.

Best,

L

Just say 100% male. The ratio definition is arbitrary. So long as you define it

Trying to get details

Thank you very much @Andrew Paul McKenzie Pegman

there is not sex ratio

I agree, just say 100% male. Of course the interesting part of this is that whatever creature you are studying has a segregated male population (bachelor herd). The breeding males and females are probably somewhere else. 100% female I can understand as evidence of parthenogenesis. A subpopulation of 100% males indicates that there is something interesting going on somewhere else. What creatures are you studying?

COLLEMBOLA, some species are partenogenetics by Volbachia. When you found, in a pitfall, only males perhaps there is one female, and there are hundreds of males. In Carabidar happen that the female is able to go out of the pitfall but in the medium remains its hormone...atracting males

Thank you very for the answers. I am studying a moth population, I rear them and in some samples only females emerged. I found a formula which helped me. Sex ratio = number of males / (number of males + number of females). With this, I resolved the problem

Only males emerged?

It is posible if a female with the gene sexual determination is transposed to an autosome or other cromosome

Yes, only males, sorry.

Or it can just be a stochastic process, because in majority of subpopulations, both males and females emerged

100% male is 1 unit of sex ratio

Ok Clemente

When i was studying a parasitoid wasp emerging from populations of a moth i encountered a similar problem. Several subpopulations where 100% male. I solved the problem by simply expressing the sex-ratio as a fraction. For example for a sex ratio of 1 I would write 1/1. When there where 54 males and 37 females I would write 54/37 or actually rather 1,46/1 instead of just 1,46 and of course when the subpopulation was 100% male I would write 1/0.

Have you considered a kind of Allee-effect as a reason for this sex ratio? Some insects seem to produce purely male or female eggs, when not inseminated. This way when a local population drops below a critical density some females only produce male or female eggs when no sexual partner can be found. This seemed to be the case for my parasitoid. When the population density dropped below a certain limit all eggs where male. I guess this reaction is increasing the chances of insemination for the remaining females in the area. It may also be an adaption to strong fluctuations in the population density of the host species, as a parasitoid does not have any benifit from an equal sex ratio if there are very little hosts to parasitize.

One usual way of expressing a sex ratio is to use a colon to give actual data, which can then be used by any reader to assess the significance, and percent male to compare results easily. For example:

182 male : 379 female (32.4% male)

In fact, the term "sex-ratio" is misleading, and the formula "males/females" should be avoided. Only a minority of authors use this formula.

Practically, most authors use the formula "males/(males+females)". This can be expressed as a probability (range: 0-1) or as a percentage (*100). It should be properly called "male proportion" but the (misleading) term "sex ratio" is traditional.

Best,

L

Thank you all very much.

I found a book "Sex ratios" from Ian Hardy. It was very helpful. If someone else is interested, you can find a vook on RG or I can send you a book

You can just describe the number of males and females respectively.

Yes, it works as far as you wish to describe a single sample.

Then you have to describe how sex-rato depends on another character, like age class, group size, or an environmental factor. Then the difficulties come.

Best, L.

In that case, just mention no female individuals were found in the final outcome, or any similar words.

food for thought !!!!!

you can write "not defined"

What if we mention 2:0 for two males are proportional to nil female? is it acceptable? just curious.

Sex ratio is the ratio of males and females in a population. In most sexually reproducing species, the hypothetical sex ratio tends to be 1:1, when number of both males and females are equal. Sex ratio is determined as- number of males/number of females. But, in an environment when the number of female is zero i.e. the population consists of n (100%) number of male species then the sex ratio n/0 is valueless or invalid.

Filip N. Vukajlović Could you share with me, the book related to sex ratio.

Thank you

Dear Kariyanna B.

You must applied a male proportion formula (M/M+F).

This can help you in field.

Thanks Lajos Rozsa

Dear Bara Mouslim

(M/M+F) is the formula of sex ratio?

The vast majority of authors use the formula M/(M+F).

Very few authors use M/F, which is problematic.

Cheers, Lajos

Please justify it

If

Male= 1521

Female=576

what will be the sex ratio???

please give its answer with explanation. how???