How common is sex between different species of animals?

The original question as it was written:

How common is sex between different species of animals?

Specially interested in sex between species which cannot produce hybrid offspring together.

So, this another question posted on Quora. I understand that the poster stressed the point that the two species weren't able to produce hybrids together because their intention was to find how common was sex for the sake of sex in the case of different animals.

And I opened my big mouth, I mean I started to type this answer looking for being clear and open minded. Enjoy...

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No, I am not telling that there is an evolutionary reason to find goats sexy, and I would not sympathise with anybody that would use this as an excuse. I am just talking about facts recorded in the wild, but never, never will admit they are an excuse for human behaviour.

But, interspecific intercourse is more common than I used to think.

I thought this event took place in human designed enviroments (planned interbreeding as in mules, and sex for the sake of having fun among animals not very stressed by the need to runaway predators, this was my mental scenario), but not...animals, stubborn creatures always find a way to cheat the rules. Why?, because they are stubborn rulebreaker maniacs, this is my current hypothesis. Anybody wants to defy it?...
The best clue that some interspecific sex has been there, are hybrids. And there some weird examples of hybrids in the wild:

• Natural hybrids populations of lemurs in Magadascar: DNA analysis indicates that the population  at Andringitra is a hybrid population between the two species. -> Source: http://messybeast.com/genetics/h...

• Hybrid wild dolphins (yes, dolphins are horny, but it would be more logical that they could only produce offspring in captivity, but...again stubbornnes won logic): In 1933, three strange dolphins were  beached off the Irish coast that were apparent hybrids of Risso's Dolphin and Bottlenose Dolphin, and this hybridation was later proven to be possible in captivity.There are also reports of possible hybrids of bllue Whales, Fin Whales and Humpback Whales in the wild. Source->http://messybeast.com/genetics/h...

(If you feel more curiosity about hybridization, there are hundreds of them compiled in Sarah Hartwell´s site - http://messybeast.com/genetics/h... it is amazing, and she is very strict with the material she uses, I recomend it).


But the conclusion is that yes, different species mate in the wild.

• Most of the time we can not keep man's influence off the equation, loss of habitat has impossed many animals an added difficulty to fin a mate, and has push together species that used to be isolated.  This is explained under the epigraph "Introduced species and habitat fragmentation" in http://en.wikipedia.org/wiki/Hyb....

• But this does not explain all cases of interspecific matings in the wild. There are some extremely bizarre cases that are not even taken into account in this article in the wiki (a suggestion, include them, they are amazing, or sexy, or whatever, but deserve a place in this wiki article): Sexual parasites, forced hybrids. Sexual parasites offer unique insights into asexual and sexual  reproduction. They mate with a ‘host’ whose genetic contribution is  discarded either immediately (in androgenesis or gynogenesis) or after a  delay of one generation (in hybridogenesis). The discarded genome can  be maternal or paternal, implying that not only females but also males  can reproduce asexually. The resulting lineages are often older than  ecological or evolutionary theory predicts.-> http://www.sciencedirect.com/sci....

And all this talking only about hybrids (I would say that in the last case not the type of hybrid we should expect, only clever animals hacking sex for reproducing breaking the laws of sexual reproduction. Stubbornnes and animals again).

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Well, reading my answer again I realize that I have talked about hybrids once and again. Well, take into account that for needing that two species different generate an third hybrid species (the case I've talked about beneath these lines), we need first two different species. On many ocassions these species mate because they were iniatilly one species that diverged into two, and they were different enough to produce a third one together. See this interesting article here: http://arstechnica.com/science/2016/10/what-happens-when-you-end-up-with-an-extra-genome/.

 

But on many ocassions animals mate with animals of different species just because it happens:

Some animals opportunistically mate with individuals of another species. This is more commonly observed in domesticated species and animals in captivity, possibly because captivity is associated with a decrease in aggression and an increase in sexual receptivity.^[52] Nevertheless, animals in the wild have been observed to attempt sexual activity with other species.^[53] It is mostly documented among species that belong to the same genus, but sometimes occurs between species of distant taxa.^[54] Alfred Kinsey cites reports of sexual activity involving a female eland with an ostrich, a male dog with a chicken, a male monkey with a snake, and a female chimpanzee with a cat.^[55]
A 2008 review of the literature found 44 species pairs that had been observed attempting interspecies mating, and 46 species pairs that had completed interspecies matings, not counting cases that had resulted in hybridization. Most were known from laboratory experiments, but field observations had also been made.^[54] It may result in fitness loss because of the waste of time, energy, and nutrients.^[54]
Male sea otters have been observed forcibly copulating with seals,^[56][57] and male seals have been observed forcibly copulating with penguins.^[58] Male grasshoppers of the species Tetrix ceperoi often mount other species of either sex and even flies, but are normally repelled by the larger females.^[54] Males of the spider mite species Panonychus citri copulate with female Panonychus mori mites almost as often as with their own species, even though it does not result in reproduction.^[54]
 (https://en.wikipedia.org/wiki/Non-reproductive_sexual_behavior_in_animals#Cross-species_sex).

How do birds treat dying family members?

Many birds simply leave alone or even kick out others that look ill.
Parents of many songbird chicks will stop feeding them and leave the nest if they feel there is a big predator near, and if humans handle the chicks or the nest.
It is said that psitacids attack ill members of their group to death -about this particular point I have not source- and many vets advice to separate ninfas or agapornis pairs when one of them looks ill, just to avoid the other one kills it.
Migrant bird can leave a healthy set of chicks if migration time has arrived, it has been observed in Apus apus and some other, by example in Hirundo rustica this behavior is less frequent.
But when it comes to birds and mammals every coin has two sides. They can be very compassive and even make an enormus effort to help a dying mate (1), and there have been studies that the have a notion of death and even mourning rituals (2).

(1) Difficult to believe?, take a glance to this web page: One of Life’s Tiny Dramas Captured Forever on Film

Image: Wilson Hsu

For homosexual animals, how would a female win over another female instead of fighting for her like a male?

Ok, before you feel the need of telling me that animals are not homosexuals (or that they are), or that asking specifically about females is just...a bit narrowed minded, let me explain that this is a question written in Quora and I have copied it here just in the way it was written.
Here is the complete question:

For homosexual animals, how would a female win over another female instead of fighting for her like a male?
Like a deer, a female usually doesn't have antlers, so she can't fight heterosexual males. How would homosexuality play for females in order to impress a mate? Again, a bird, a male bird has flashy colors while a female has camouflage, so homosexual female birds?

Well, the author of the question is apparently appaled by what they think it is a lack of chances for "homosexual" females, that lack in their opinion strength and appeal to attract or fight for another female...
hmmm...
If it were this way homosexual behavior in females would be very weird. But not, there are a bunch of examples that tell us that this is not the case.
Another answer on Quora (so long and thnks for all the fish, yes). Enjoy...
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 If the animals "follow" the rules of the species, it is not neccessary to "fight". For example, female deers in the same harem don't have to fight any male to have an homosexual moment.
So, the interesting thing here is to find some species in which females want to form their own homosexual unions fighting males. And in spite that -in gneral- scientists are quite more focused in what males do, yes, there are some studied cases of stable female unions that exclude temporaly males. And what seems to be the norm in these cases is that females choose to form the bond, they don't have to fight males to attract females, although this doesn't exclude that both females have to fight males that want to break their bond.

- Japanesse macaques is one example.  In some populations (notice the word population), homosexual behaviour among females is not only common, it's the norm. 
The pairings can even last a whole week, mounting hundreds of times.  When they're not mating, the females stay close together to sleep and  groom, and defend each other from possible rivals. Males don't just have to compete with other males for access to females: they have to compete with females too. In this species there is sexual dimorphism (Males weigh on average 11.3 kg , while females average 8.4 kg. Macaques from colder areas tend to weigh more than ones from warmer areas).
So what seems to explain the atachment between the females is pure and simple sexual attraction and the deed of them. So, females don't have to fight to gain females, they just choose each other, at least for some weeks.
But, these females don't exclude posterior mating with males.

Another interesting case, is the Laysan albatros which nests in Hawaii.
Among  them, pairs are usually "married" for life. It takes two  parents working together to rear a chick successfully.
But in one population on the island of Oahu, 31% of the pairings are made up of two unrelated females.  What's more, they rear chicks, fathered by males that are already in a  committed pair but which sneak matings with one or both of the females.  Like male-female pairs, these female-female pairs can only rear one  chick in a season. Again, in this case, it is the choice of the females, that don't exclude mating with males, what we see.

Source: http://www.bbc.com/earth/story/2...

Do female animals (reptiles, mammals, birds, etc) have menopause?

Another one from Quora, the site that used to have interesting contents, and then decided to go for quantity forgetting quality. So long, Quora, and thank you for all the fish.

But my content is still my content, agree?.

Ok, continuing with the topics related with menstruation, that great and very poorly understoood territory, we have to arrive to an important landmark, menopause. Enjoy...

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We have to differentiate menopause from simple gradual senescence that gets to the declive of fertility in many animals. Fertility loss due to aging is found in all placental mammals, to give you an important reference.

Menopause should be understood as the loss of reproductive cycles and hence the possibility of producing offspring in females that still have a relatively long period of life ahead of them, just in the way we understand it in humans.Perhaps some biologists and physicians reading it find this definition very weird, as they focus their understanding of reproductive cycles in human models, and the loss of menstruations. But recent studies of animal menstrual periods, and mentruation indicate that we have to widen the concept to include the many phenomenons related to reproductive events in female animals.

Yes, menopause is known in some species of mammals such as rhesus monkeys, short finned pilot whales and other types of cetaceans as the Orca, laboratory rat and opposums. It has also been reported in some species of fish, such as guppies and platyfish; and birds as the budgerigar.

However, with the exception of the short finned pilot whales, such examples tend to be from captive individuals, and thus they are not necessarily representative of what happens in natural populations in the wild.

Short finne pilot whale, photo of Short-finned pilot whale

The controversy about menopause in chimpanzees:

To give you an example of an animal that has suscited many doubts about having or not a menopause period, the chimpanzee (in fact they are listed in the wiki article referring to menopause in animals, Menopause , but this is controversial as I will explain here). Although there have been some studies in captives chimpanzees pointing out that females tend to experience menopause after their 35 years (and I apologize because I haven't found many of them), later studies in wild chimpanzees contradict those ones stating that what in fact happens is that the senescence of the reproductive organs goes in paralel with the overall age declive. Also, there is an remarkable study of the Yerkes centers with captive chimps that agrees with this conclussion.

Auntie Ross a wild female was about 55 when this photo with his youngest son was taken. She lived 63, an incredibly longevity for any chimpanzee, both captive and wild, and in her final year there were fights among the males of her group to mate with her. As it is easily noticeable in the pic, she presents the signs of senescence, balding, greying and loss of shape, and still she was having her cycles. So this is a clear illustration of that what happens (at least in wild chimps) is that the senescence of reproductive cycles goes hand by hand with the normal aging declive.

Menopause in chimps? Or not? (Menopause not, aging).

Menopause occurs late in life in the captive chimpanzee (Pan troglodytes) (Menopause in very old chimps).

The effects of aging on hormone and reproductive cycles in female chimpanzees (Pan troglodytes).  (Menopause in old chimps, using an indirect method of meassuring LH and FSH).

In my opinion, and here I am only expressing my personal thoughts, it would be very useful to rescue the former studies that talk about menopause in captive chimps, and investigate what type of feeding they had. Because I think that many problems in reproductive cycle are linked to nutritional factors.

There are also some articles that talk about menopause in captive gorillas (Female Gorillas Go Through Menopause, Zoo Study Shows ), but I think that when they study it in wild ones will find the same pattern that in captive versus wild chimpanzees.

About the evolutionary advantages of menopause in humans (women) pointed by some studies, I think that they are very hasty, and made with the tyoical mentality of having to explain it all as an adaptation phenomenom.

Menopause in animals is very poorly studied, as it is menstruation, so probably the mindset will change as far as more studies are made.

What are some species whose females commit infanticide in order to access to males to mate with? Females mirrorring the behavior of lions.

Animals are the greatest ruler breakers you can imagine. And when there is a rule, very surely there are some animal species able to break it. Although it is true that there are there are less females that commit infanticide due to sexual conflict than males, those females exist.

Ok, they are females mirroring lions (obviously males) for some extent.  There is a nice, in reality terrible concept, called Sexual conflict , that occurs when the two sexes have conflicting optimal fitness strategies concerning reproduction, particularly over the mode and frequency of mating, potentially leading to an evolutionary arms race between males and females.

These females are looking for males to mate with, and why are those males not expelling their hearts off, running to mate with them?. Because they are very busy raising up their own offspring, single parenting them.

This scenario is impossible for mammals, mothers have to lactate their offspring. But when you lay eggs...the world is broader place for you, and not all of them decide to stay at home.

Some examples:

Wattled jacanas (Jacana jacana)

 

Does she resemble a lion?. Yes, when you learn some things about her.

A wading bird from Panama. In this species  it is exclusively the male sex that broods, while females defend their territory. Wattled jacana

In a thoroughly documented research Stephen Emlen and Natalie Demong showed female infanticide of chicks. I don't agree with so intrussive experiments, and less than that with shoting females, but in any case the results of the experiment were spectacular. They found that removing females from a territory (a result they got shoting at them) resulted in nearby females attacking the chicks of the male in most cases, evicting them from their nest. The males then fertilized the offending females and cared for their young.

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Female rats will eat the kits of strange females for a source of nutrition, and to take over the nest for her own litter

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Infanticide is also seen in giant water bugs.

Lethocerus deyrollei is a large and nocturnal predatory insect found in still waters near vegetation.

Do female dolphins menstruate like other mammals? If so, why aren't they killed by sharks being attracted to their blood?

Oh, well, I'm talking about menstruations so often that on some ocassions I jest with the idea of recalling the blog vadereglas instead of vadebichos.
This is another approach to the matter of menstruation in mammals. I find this topic of menstruations not only interesting and important but also poorly investigated and explained so far. While docs continue telling that only women menstruate and there are only two models of reproductive cycles in  placental mammals, with or without menstruations, scientific proofs against this dualistic model are acumulating. So an urgent revision of this dual model (estrous cycles versus menstrous cycles) is needed, and a more generalistic view of the different cycles mammals have.

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Dolphins don't menstruate, however they bleed during labor. There is no data about how they manage to avoid sharks attacks, but it is a good question:

 They don't menstruate, I mean that they don't spell menstrual blood through their vaginas. I'm being very graphic in order to be very clear.
But there is a especially delicate moment when they do bleed, the delivery, as you may have guessed. I'm afraid that I don't know how they manage to avoid sharks attacks, as far as a few as almost none wild dolphin labor as been documented.  But it is a very reasobable question.

Image from http://imgur.com/gallery/fvJ1UfN, however i would like to know the author to give them credit. Love the vision of actual blood in this image of a dolphin labour.

Although female marine mammals don't mentruate, other mammals, besides women, do: 

 Coming back to menstruations and female mammals, generally speaking there are two different types of reproductive cycles called estrous cycles and menstrual cycles. Although they differ in a number of characteristics, the most significative one is that females with menstrual cicles shed the endometrium during the menstruation if they haven't became pregnant, while femaless (lucky them) with estrous cycles reasorb it or just maintain it.While it's very commonly believed that  many mammals menstruate, menstruation is only found in a few disparate  mammalian groups. Humans, other apes, and Old World monkeys menstruate.  (These groups form clade Catarrhini.) Some other primates may  menstruate. Although some scientists opine that only primates mensturate basing it in a very narrow vision of this phenomenon, menstruation has been found in four bat species in  two bat families, Phyllostomidae and Molossidae, and elephant shrews/sengis, relatives of elephants and aardvarks.

However, only women menstruate so copiously. Menstruation is such a great taboo that very few scientists have wondered how early women could cope with it in a enviroment full of predators. And none has answered this question.
But menstruation is only copious in human females.
I suffer my own bunch of problems related to menstruation, as many other women do. Due to them I have wondered many times how was it possible for early women to cope with abundant blood discharges in an enviroment full of predators, with the logical danger of attracting them.
I have not found any paper related to it. It seems that it is not a matter many investigators have thought worth to be studied.
There are tones of anthropological papers that describe ad nauseam customs related to menstruatio in tribal people, such as mentruation huts, celebrations of first menstrual bleed, etc. But they don't get into describing if those menstruations are abundant, painful or regular.
I have discussed these items with a friend who is also interested in menstruations, I have kinda of scientific background while she is more on the multicultural perspective. She said to me that some of her African friends, who have a totally different diet from ours, have reported her that they menstruate every two or three months (instead of monthly) and that their menstrual bleed is by no means so copious as ours. And they are fertile.

In my opinion, mentruations shouldn't be so copious or painful at all. It is an indicative that something is wrng in our lifestyle and many women are suffering for it. Menawhile this seems to follow unnoticied, talking about menstruation is minded as disgusting and even sceintits are unable to break the enourmous taboo we have with it.