Do animals mate with their parents, siblings, and offsprings?
Yes, animals mate with their parents, siblings, and offspring. But not all animals mate in such away.
For instance if you see, Banded mongoose females from South Africa can regularly mate with their fathers and brothers. They can tolerate incest and are able to genetically withstand the effects of inbreeding quite well.
Higher animals like lions mate with their parents, siblings, and offsprings. That’s rare, but they do when they have no better choice.
Lions group consists of one primary male lion, several females, and one or two lesser males. The primary male mates with his lionesses. Females might also mate with more than one partner.
Inbreeding is well seen in lions when the dominant male is killed or kicked off out of the pride by one of the bachelor males. This can be also like a father lion is getting replaced by his son.
Almost in the majority of the scenarios, you will find that most of the lionesses in a pride are related to one another as siblings, cousins, or nieces. And this is what happens in the wild, as there is no definite mechanism for preventing inbreeding or to ensure outcrossing.
Such a condition when individuals of the same lineage with close genetic traits mate to reproduce, such as between mother, and offspring or siblings then that condition is termed as inbreeding.
There’s a difference between incest and inbreeding. The difference is that inbreeding means producing offspring from incest, while incest only implies sexual intercourse possibly without offspring.
In nature, not all animals that are alive to date will mate in such a way, that is incest and inbreeding don’t occur with all animals.
Nature has made it hard for them to mate as the genetic parents, siblings, and offsprings remain dispersed from each other in the wild.
And moreover, the pheromones that the individuals release to attract mates doesn’t make any sense of attraction when it comes to choosing for mates between the members of the same genetic family members.
Just for instance in the case of hyena, wild dogs, lions, etc. you’ll often find that they use a trick unknowingly, that is usually the male leaves the group at adolescence. That way they can’t mate with their own family.
Presumably, this dispersal behavior evolved because males who left home had more offspring who would in turn carry on behaving this way. That’s how genetics have worked during evolution and is still working.
For another instance, you will also find that the males of Wild house mice, many species of snakes, etc. rely on specially evolved proteins that are released from the body of the female to sniff out and avoid mating with their close relatives.
After smelling their close relative the males and the females don’t get that sense of sexual attraction and feeling to continue mating if the smell is from their own genetic family members. However, if the smell is from a non-genetic relative they are all okay to continue mating.
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Do animals have any relations sense like we humans?
Yes, animals do have a kind of relation sense to recognize and differentiate the members of their own family and out of the family.
The higher the phylum of the animals if you move from the invertebrates to the vertebral mammals the better the sense of relation they have to recognize the members of the same family.
For example, humans that belong to the higher animals of the Class Mammals have the best kind of relations and social behaviours between their own family members and can recognize their mom, dad, offsprings, and siblings very well.
In the same way, if you consider other like wild dogs, elephants, hippopotamus, and thousands of others, you will also notice that the mom and dad better know their siblings and offsprings, and the same way the offsprings better know their parents.
But, if we consider the lower invertebrates like earthworm, starfish, jellyfish, and millions of other, then we’ll hardly find and recognize the relations between mom, siblings, offsprings, and neither they are able to know the relations.
So, may be that’s why you will often see lower invertebrate animals mating with each other as they don’t have any kind of a relation sense.
However, higher animals like we are, have good sense of relation and we have social behaviours that don’t allow us to mate with our own genetically related family members like sex between mother, offsprings, and siblings.
Does inbreeding affect animals?
Yes, inbreeding can badly affect higher animals like sharks, humans, dogs, and almost 90% of the vertebrates.
Inbreeding in the majority of the higher animals can cause many deleterious effects as it can pause genetic variation, and genetic variation is the cause of evolution due to better adaptation.
There also occur another negative effect of inbreeding like a very weakened immune system due to the less diverse immunity providing alleles.
While inbreeding increases the risk of passing on faulty genes, it also ensures the preservation of good genes within a population. So, for inbreeding, there are both pros and cons.
And in nature when the pros of inbreeding outnumber the cons, the behavior may become common practice.
So in addition, some species must only inbreed out of necessity, that is simply because they are unable to find suitable mates. That’s an exception and not always happen in nature.
However, inbreeding doesn’t affect in any mean to the majority of lower groups of animals like all of the invertebrates. They produce offspring in a lot of quantity and when offspring grows they can mate with their genetic mom and dad without any issue.
So, in simple words, inbreeding is good for lower groups of animals as they help them to better multiply and continue their generation without any worries.
But, for higher groups of animals inbreeding is possibly prevented naturally, without even the members knowing about it, due to the deleterious effects.
Nature’s working is in such a way that it avoids inbreeding between the individuals in the case of higher animals. So, the animals unknowingly don’t incest and inbreed as their body physiology and psychology don’t allow them to initiate such an act.
For instance, if you see, invertebrates like Bed bugs in contrast to most other insects, tolerate incest and inbreeding, and are able to genetically withstand the effects of inbreeding quite well.
However, in the other case, if you see, invertebrates like honeybees don’t inbreed as high genetic diversity among the workers is important for the whole colony’s survival. The queen bee doesn’t inbreed and maintains high genetic diversity for their good.
The queen bee can solve the problem of inbreeding in two ways. First is by following the process of polyandry, which is that she mates with a large number of male drones and uses their sperm to fertilize the eggs randomly, and it is why so the worker bees often have different fathers. The second is by following the extremely high rate of genetic recombination that diversifies their generations with causing no occurrence of inbreeding.
So, you can easily see that nature has set some rules according to the body physiology of animals which can inbreed, for withstanding the effects of inbreeding quite well.
However, for those who don’t normally inbreed, if inbreeds due to various unusual circumstances, then the offspring and their future generations have to withstand various deleterious effects, and as a result, many will die too soon and the lineage can even become extinct if they are not able to withstand those deleterious effects.
How do animals prevent inbreeding?
The process by which animals prevent inbreeding is by inbreeding avoidance. This inbreeding avoidance helps in the prevention of the deleterious effects of inbreeding.
Animals prevent inbreeding in nature by at least following the four mechanisms. These are – (1) Kin recognition, (2) Dispersal, (3) Extra-group copulations, and (4) Reproductive suppression.
1. Kin recognition
Also known as kin detection, kin recognition, can be defined as the way and ability of an organism to properly distinguish between their close genetic kin and non-kin.
In the books of evolutionary biology and psychology, it has been researched and stated that such a kind of kin recognition ability has been evolved for inbreeding avoidance. And, recent studies have shown that kin recognition can result from a multitude of sensory inputs.
Kin recognition is a behavioral adaptation noted in many species but the exact, proximate, and well-strategic level of mechanisms for doing so are not well documented.
For example: Golden hamsters (a type of rodent) have been shown to use their own phenotypes as a template in order to differentiate between kin and non-kin via. olfaction (capacity of smelling).
When a group of living organisms tries to expand their boundaries just in order to increase their territories and expand the space or range within which they live, can be defined as Dispersal.
Dispersal can also occur when individual organisms leave the space in which they were born and go settle in new different areas.
Meaning that during Dispersal individual organisms can leave the space that they have previously occupied or can even expand that previously occupied space.
Thus, dispersal helps prevent inbreeding as some species will adopt dispersal as a way to separate close relatives and go far from each other.
For example: Australian marsupial juvenile males have a greater tendency to disperse from their natal groups, while the females tend to return to or remain to the same natal group.
3. Extra-group copulations
This is one of the most common types of inbreeding avoidance methods. This is commonly seen in birds.
In monogamous species, extra-pair copulation is very common. Monogamous species have only one sexual partner with whom they will be forming a long-term bond and they both will also show their combining efforts to raise offspring together.
Extra-pair copulation occurs when one of these monogamous individuals mates outside of their long-term pairing.
For females, extra-pair copulations ensure the proper egg fertilization. It also ensures the enhanced genetic variety in the species with compatible sperm that avoid the expression of damaging recessive genes that come with inbreeding.
For males, extra-pair copulation involves spending more time away from the original pairing in search of other females.
For example: Zebra finches of Central Australia are socially monogamous, but they do engage themselves in extra-pair copulations.
4. Reproductive suppression
The delayed sexual maturation is also termed as reproductive suppression. Reproductive suppression of offspring in the presence of parents is another mechanism by which individuals avoid inbreeding.
In simple words, reproductive suppression involves the prevention or inhibition of reproduction in otherwise healthy adult individuals.
In the animal kingdom, there are actually countless strategies via which males optimize their reproductive success by causing reproductive suppression when faced with male-male competition.
These male strategies typically fall into two main categories: pre-copulatory and post-copulatory competition.
For example: In Polygynandrous yellow baboons (Papio cynocephalus) in Kenya, it has been seen that they try to avoid to ovulate or conceive during periods of extreme drought or heat. This kind of behaviour can actually be seen if they live in very large groups, resulting in longer interbirth intervals during extreme periods of stress.